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Chayer M, Phan P, Arnoux PJ, Wang Z, Rawlinson JJ, Aruwajoye O, Aubin CÉ. Understanding the influence of cage and instrumentation strategies with oblique lumbar interbody fusion for grade I spondylolisthesis - A comprehensive biomechanical modeling study. Spine J 2025:S1529-9430(25)00186-X. [PMID: 40194709 DOI: 10.1016/j.spinee.2025.04.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2024] [Revised: 03/11/2025] [Accepted: 04/01/2025] [Indexed: 04/09/2025]
Abstract
BACKGROUND CONTEXT Proper implant selection and placement in oblique lumbar intervertebral fusion (OLIF) are essential to achieve the best possible results for the patient. Key factors such as interbody cage length, height, angle, and material must all be carefully considered to achieve the intended results and minimize complications. Significant challenges remain in selecting the appropriate cage parameters to control spinal alignment while minimizing subsidence risk. Ongoing debates include how long a cage should be to optimize load distribution, as well as how variations in cage angle and placement influence the outcomes. PURPOSE This study aims to biomechanically model and investigate how variations in interbody cage dimensions, positioning, and material properties influence indirect decompression, realignment, and resulting stresses involved in cage subsidence. STUDY DESIGN Computational biomechanical study of interbody cage and OLIF influence on correction outcomes. METHODS A pathological finite element model of the L4-L5 segment presenting a grade I spondylolisthesis was used to simulate 172 different OLIF configurations, evaluating cage position (anterior, central, posterior), angle (6° or 12°), material (PEEK or titanium), length (40-60 mm), and height (10-14 mm). Bilateral pedicle screw fixation was also tested. The simulated outcomes included disc height, foraminal and spinal canal dimensions, segmental lordosis, vertebral slip, endplate stresses, and displacements under various loading conditions. Statistical comparisons were tested to analyze the influence of model, implant, and surgical parameters on correction outcomes. RESULTS Longer (left-to-right dimension) cages (60 mm), which overhang on both sides of the vertebrae and sit on the apophyseal ring, significantly reduced vertebral endplate displacements and stresses by 33 % compared to shorter cages (40 mm) (p < 0.05). Posterior cage positioning improved the decompression but raised stresses by 45 % and reduced segmental lordosis by 28 %. Lowering cage height from 14 to 10 mm and increasing the angle from 6° to 12° reduced endplate stresses by 53 % and 33 %, respectively. BPS fixation decreased stresses by 36 % on average. The trends observed concurred with recently published OLIF clinical studies. CONCLUSIONS This study highlights the biomechanical influence of implant characteristics and positioning on OLIF results and subsidence risks. Competing factors unveil an optimization problem that can be effectively addressed with the help of accurate, robust, and reproducible numerical simulations and regression models. This study further confirms that the developed tools not only accurately simulate the surgical approach and corroborate clinical findings but also offer a relevant framework for in-depth analysis. CLINICAL SIGNIFICANCE Leveraging numerical methods, this study provides biomechanical insights into how variations in cage parameters during OLIF procedures influence outcomes. The findings aim to help clinicians refine strategies to attain desired outcomes (decompression and alignment) while understanding the consequences on the risk of subsidence. By aligning with clinical trends, our results offer valuable explanations and support for biomechanical-based surgical decision-making.
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Affiliation(s)
- Mathieu Chayer
- Institute of Biomedical Engineering, Polytechnique Montréal, PO Box 6079, Montreal, QC H3C 3A7, Canada; Sainte-Justine University Hospital Center, Montreal, Canada
| | - Philippe Phan
- Division of Orthopaedics, Department of Surgery, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Pierre-Jean Arnoux
- Laboratoire de biomécanique appliquée, Aix-Marseille Université/Université Gustave Eiffel, Marseille, France
| | - Zhi Wang
- Centre Hospitalier de l'Université de Montréal, Montreal, Canada; Department of Surgery, Faculty of Medicine, Université de Montréal, Montreal, Canada
| | - Jeremy J Rawlinson
- Department of Mechanical Engineering, Polytechnique Montréal, P.O. Box 6079, Montreal, QC, H3C 3A7, Canada; Spine Applied Research, Cranial and Spinal Technologies Medtronic, 18400 Pyramid Place, Memphis, TN, 38132, USA
| | - Olumide Aruwajoye
- Spine Applied Research, Cranial and Spinal Technologies Medtronic, 18400 Pyramid Place, Memphis, TN, 38132, USA
| | - Carl-Éric Aubin
- Institute of Biomedical Engineering, Polytechnique Montréal, PO Box 6079, Montreal, QC H3C 3A7, Canada; Sainte-Justine University Hospital Center, Montreal, Canada; Department of Surgery, Faculty of Medicine, Université de Montréal, Montreal, Canada; Department of Mechanical Engineering, Polytechnique Montréal, P.O. Box 6079, Montreal, QC, H3C 3A7, Canada.
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Kurland DB, Givens RR, Concepción-González A, Eremiev A, Dastagirzada Y, Alexiades N, Roye BD, Vitale MG, Anderson RCE. Maintenance of construct integrity with subaxial cervical pedicle screws when crossing the cervicothoracic junction in complex pediatric deformity: an international multicenter study. Childs Nerv Syst 2025; 41:138. [PMID: 40119893 DOI: 10.1007/s00381-025-06791-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2024] [Accepted: 03/09/2025] [Indexed: 03/25/2025]
Abstract
OBJECTIVE In cases of complex pediatric spinal deformity, posterior spinal instrumentation crossing the cervicothoracic junction (CTJ) may be required. This is most frequently encountered for revision surgery to address proximal junctional kyphosis (PJK). In the cervical spine, lateral mass screws are most commonly used, although they may result in biomechanically weak proximal constructs and predispose to instrumentation failure. The use of supplemental anterior constructs has recently been reported with promising results, but this necessitates an additional surgical procedure. Subaxial cervical pedicle screws can provide good biomechanical fixation without the need for an anterior approach, but outcome data have been very limited. The purpose of this study was to assess radiographic and clinical outcomes at two years in pediatric patients who have undergone posterior spinal instrumentation and fusion (PSIF) crossing the CTJ using subaxial cervical spine pedicle screws. METHODS The Pediatric Spine Study Group (PSSG) registry was queried to identify patients ≤ 21 years old who underwent PSIF crossing the CTJ with two-year minimum clinical and radiographic follow-up. Patients were excluded if they had a history of anterior stabilization or if their fusion construct with subaxial pedicle screws started below C6. Clinical, surgical, and radiographic parameters were assessed, and measurements were compared statistically. RESULTS Then, 8 patients (6 female and 2 male) met inclusion criteria, with a mean age at surgery of 11.2 ± 3.3 years. All patients underwent PSIF crossing the CTJ (mean levels fused 15.6 ± 6.6). The mean density of subaxial cervical pedicle screws was 61.9% ± 27.8 (range 28.5 to 100%). The major coronal curve averaged 54.7° ± 19.6 preoperatively and 34.5° ± 13.6 postoperatively (41.5% ± 26.5 correction; p = 0.03). The average major sagittal curve was 55.9° ± 20.6 preoperatively and 29.6° ± 9.6 (44.2% ± 18.0 correction; p = 0.01) postoperatively. There were no major intraoperative or postoperative complications. Deformity parameters remained stable without radiographic evidence of PJK in 8/8 patients at minimum 2-year follow-up. CONCLUSIONS In this small preliminary international series of pediatric patients with spinal deformity, the inclusion of subaxial cervical pedicle screws in constructs that span the cervicothoracic junction resulted in good clinical and radiographic outcomes without major complications. Subaxial cervical spine pedicle screws provide enhanced biomechanical stability and may eliminate the need for additional anterior support in pediatric patients.
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Affiliation(s)
- David B Kurland
- Department of Neurological Surgery, Hassenfeld Children'S Hospital, NYU Langone Health, NY 462 1st Avenue, Suite 7S4, New York, NY , 10016, USA
| | - Ritt R Givens
- Division of Pediatric Orthopaedic Surgery, Department of Orthopaedic Surgery, Columbia University Irving Medical Center, New York, NY, USA
| | - Alondra Concepción-González
- Division of Pediatric Orthopaedic Surgery, Department of Orthopaedic Surgery, Columbia University Irving Medical Center, New York, NY, USA
| | - Alexander Eremiev
- Department of Neurological Surgery, Hassenfeld Children'S Hospital, NYU Langone Health, NY 462 1st Avenue, Suite 7S4, New York, NY , 10016, USA
| | - Yosef Dastagirzada
- Department of Neurological Surgery, Hassenfeld Children'S Hospital, NYU Langone Health, NY 462 1st Avenue, Suite 7S4, New York, NY , 10016, USA
| | - Nikita Alexiades
- Department of Neurological Surgery, University of Arizona - Phoenix, Phoenix, AZ, USA
| | - Benjamin D Roye
- Division of Pediatric Orthopaedic Surgery, Department of Orthopaedic Surgery, Columbia University Irving Medical Center, New York, NY, USA
- Pediatric Orthopaedic Surgery, New York-Presbyterian Morgan Stanley Children'S Hospital, New York, NY, USA
| | - Michael G Vitale
- Division of Pediatric Orthopaedic Surgery, Department of Orthopaedic Surgery, Columbia University Irving Medical Center, New York, NY, USA
- Pediatric Orthopaedic Surgery, New York-Presbyterian Morgan Stanley Children'S Hospital, New York, NY, USA
| | - Richard C E Anderson
- Department of Neurological Surgery, Hassenfeld Children'S Hospital, NYU Langone Health, NY 462 1st Avenue, Suite 7S4, New York, NY , 10016, USA.
- NYU Neurosurgery Network, Ridgewood, NJ, USA.
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Jiang Y, Wei Y, Liu Y, Yang J, Zhou K, Yang H. Bone mineral density surrounding the screw thread predicts the risk of pedicle screw loosening. J Biomech 2025; 181:112542. [PMID: 39892282 DOI: 10.1016/j.jbiomech.2025.112542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2024] [Revised: 01/08/2025] [Accepted: 01/21/2025] [Indexed: 02/03/2025]
Abstract
BACKGROUND Screw loosening remains a serious complication for patients undergoing pedicle screw fixation surgeries. An accurate risk prediction is significant for prevention of screw loosening through preoperative planning. In this study, we proposed a novel index, namely the bone mineral density surrounding the screw thread (thread BMD), and tested its predictability in screw loosening. METHODS 86 screws (18 loosening and 68 non-loosening) from L3-L5 of 20 patients who experienced pedicle screw loosening were analyzed. The preoperative and postoperative quantitative CT scans of the same vertebra were spatially registered and a helix-based approach was developed to extract the thread BMD. BMDs of the vertebral body, the pedicle and the screw trajectory were also measured from the preoperative CT scans. Finite element analysis was conducted to determine pullout strength and tissue failure around the screw. Receiver operating characteristic (ROC) curve analysis was used to assess the performances of all BMD indices and pullout strength in predicting screw loosening. Linear regression was used to examine correlations between different BMD indices and screw pullout strength. RESULTS The thread BMD had the greatest value of area under the curve (AUC = 0.73, p = 0.004) compared to vertebral BMD (AUC = 0.51, p = 0.923), pedicle BMD (AUC = 0.56, p = 0.474) and trajectory BMD (AUC = 0.67, p = 0.020). Also, the thread BMD showed a stronger correlation with the pullout strength (r = 0.83, p < 0.001) than vertebral BMD (r = 0.59, p < 0.001), pedicle BMD (r = 0.65, p < 0.001) and trajectory BMD (r = 0.60, p < 0.001). CONCLUSIONS We developed a novel approach to measure a newly-defined thread BMD, which indicates superior capacities over other BMD indices in predicting pedicle screw loosening.
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Affiliation(s)
- Yize Jiang
- Department of Biomedical Engineering, College of Chemistry and Life Science, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing 100124, China
| | - Yi Wei
- Department of Spinal Surgery, Beijing Jishuitan Hospital, Beijing 100035, China
| | - Yuxuan Liu
- Department of Biomedical Engineering, College of Chemistry and Life Science, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing 100124, China
| | - Jiaxu Yang
- Department of Biomedical Engineering, College of Chemistry and Life Science, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing 100124, China
| | - Kexin Zhou
- Department of Biomedical Engineering, College of Chemistry and Life Science, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing 100124, China
| | - Haisheng Yang
- Department of Biomedical Engineering, College of Chemistry and Life Science, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing 100124, China.
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Tsagkaris C, Fasser MR, Farshad M, Passaplan C, Cornaz F, Widmer J, Spirig JM. Stability of medially and laterally malpositioned screws: a biomechanical study on cadavers. Spine J 2025; 25:380-388. [PMID: 39357743 DOI: 10.1016/j.spinee.2024.09.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 08/07/2024] [Accepted: 09/14/2024] [Indexed: 10/04/2024]
Abstract
BACKGROUND CONTEXT Pedicle screw instrumentation is widely used in spine surgery. Axial screw misplacement is a common complication. In addition to the recognized neurovascular risks associated with screw misplacement, the biomechanical stability of misplaced screws remains a subject of debate. PURPOSE The present study investigates whether screw misplacement in the lumbar spine reduces mechanical screw hold. STUDY DESIGN/SETTING Cadaveric biomechanical study. METHODS Pedicle screw (mis)placement was planned for 12 fresh frozen cadaveric spines between the T12 and the L5 levels. The screws were then implanted into the vertebrae with the help of 3D-printed template guides. Pre- and postinstrumentation computed tomography (CT) scans were acquired for instrumentation planning and quantification of the misplacement. The instrumented vertebrae were potted into CT transparent boxes using Polymethyl methacrylate and mounted on a standardized biomechanical setup for pull-out (PO) testing with uniaxial tensile load. RESULTS The bone density of all the specimens as per HU was comparable. The predicted pull-out force (POF) for screws medially misplaced by 2 , 4, and 6 mm was respectively 985 N (SD 474), 968 N (SD 476) and 822 N (SD 478). For screws laterally misplaced by 2 , 4, and 6 mm the POF was respectively 605 N (SD 473), 411 N (SD 475), and 334 N (SD 477). Screws that did not perforate the pedicle (control) resisted pull-out forces of 837 N (SD 471). CONCLUSIONS Medial misplacement is associated with increased axial screw hold against static loads compared to correctly placed screws and laterally placed screws. CLINICAL SIGNIFICANCE In clinical settings, the reinsertion of medially misplaced screws should primarily aim to prevent neurological complications while the reinsertion of lateral misplaced screws should aim to prevent screw loosening.
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Affiliation(s)
- Christos Tsagkaris
- University Spine Center Zürich, Balgrist University Hospital, University of Zürich, Zürich, Switzerland; Spine Biomechanics, Department of Orthopedics, Balgrist University Hospital, Zurich, Switzerland
| | - Marie-Rosa Fasser
- Spine Biomechanics, Department of Orthopedics, Balgrist University Hospital, Zurich, Switzerland; Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Mazda Farshad
- University Spine Center Zürich, Balgrist University Hospital, University of Zürich, Zürich, Switzerland; Spine Biomechanics, Department of Orthopedics, Balgrist University Hospital, Zurich, Switzerland
| | - Caroline Passaplan
- University Spine Center Zürich, Balgrist University Hospital, University of Zürich, Zürich, Switzerland; Spine Biomechanics, Department of Orthopedics, Balgrist University Hospital, Zurich, Switzerland
| | - Frederic Cornaz
- University Spine Center Zürich, Balgrist University Hospital, University of Zürich, Zürich, Switzerland; Spine Biomechanics, Department of Orthopedics, Balgrist University Hospital, Zurich, Switzerland
| | - Jonas Widmer
- University Spine Center Zürich, Balgrist University Hospital, University of Zürich, Zürich, Switzerland; Spine Biomechanics, Department of Orthopedics, Balgrist University Hospital, Zurich, Switzerland.
| | - José Miguel Spirig
- University Spine Center Zürich, Balgrist University Hospital, University of Zürich, Zürich, Switzerland; Spine Biomechanics, Department of Orthopedics, Balgrist University Hospital, Zurich, Switzerland
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Fikuart M, Bullert B, Vetter SY, Franke J, Gruetzner PA, Swartman B. Effect of the cone-beam CT acquisition trajectory on image quality in spine surgery: experimental cadaver study. Spine J 2025; 25:154-164. [PMID: 39154945 DOI: 10.1016/j.spinee.2024.08.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 08/12/2024] [Accepted: 08/12/2024] [Indexed: 08/20/2024]
Abstract
BACKGROUND Intraoperative 3D imaging with cone-beam CT (CBCT) improves assessment of implant position and reduces complications in spine surgery. It is also used for image-guided surgical techniques, resulting in improved quality of care. However, in some cases, metal artifacts can reduce image quality and make it difficult to assess pedicle screw position and reduction. PURPOSE The objective of this study was to investigate whether a change in CBCT acquisition trajectory in relation to pedicle screw position during dorsal instrumentation can reduce metal artifacts and consequently improve image quality and clinical assessability. STUDY DESIGN Experimental cadaver study. METHODS A human cadaver was instrumented with pedicle screws in the thoracic and lumbar spine region (Th11 to L5). Then, the acquisition trajectory of the CBCT (Cios Spin, Siemens, Germany) to the pedicle screws was systematically changed in 5° steps in angulation (-30° to +30°) and swivel (-25° to +25°). Subsequently, radiological evaluation was performed by 3 blinded, qualified raters on image quality using 9 questions (including anatomical structures, implant position, appearance of artifacts) with a score (1-5 points). For statistical evaluation, the image quality of the different acquisition trajectories was compared to the standard acquisition trajectory and checked for significant differences. RESULTS The angulated acquisition trajectory significantly increased the score for subjective image quality (p<.001) as well as the clinical assessability of pedicle screw position (p<.001) with particularly strong effects on subjective image quality in the vertebral pedicle region (d=1.61). Swivel of the acquisition trajectory significantly improved all queried domains of subjective image quality (p<.001) as well as clinical assessability of pedicle screw position (p<.001). CONCLUSIONS In this cadaver study, the angulation as well as the swivel of the acquisition trajectory led to a significantly improved image quality in intraoperative 3D imaging (CBCT) with a constant isocenter. The data show that maximizing the angulation/swivel angle towards 30°/25° provides the best tested subjective image quality and enhances clinical assessability. Therefore, a correct adjustment of the acquisition trajectory can help to make intraoperative revision decisions more reliably. CLINICAL SIGNIFICANCE The knowledge of enhanced image quality by changing the acquisition trajectory in intraoperative 3D imaging can be used for the assessment of critical screw positions in spine surgery. The implementation of this knowledge requires only a minor change of the current intraoperative imaging workflow without additional technical equipment and could further reduce the need for revision surgery.
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Affiliation(s)
- Maxim Fikuart
- BG Klinik Ludwigshafen, Department of Orthopedics and Trauma Surgery, Research group Medical Imaging and Navigation in Trauma and Orthopedic Surgery (MINTOS), BG Klinik Ludwigshafen, Ludwig-Guttmann-Str. 13, 67071 Ludwigshafen, Germany; Heidelberg University, Grabengasse 1, D-69117 Heidelberg, Germany
| | - Benno Bullert
- BG Klinik Ludwigshafen, Department of Orthopedics and Trauma Surgery, Research group Medical Imaging and Navigation in Trauma and Orthopedic Surgery (MINTOS), BG Klinik Ludwigshafen, Ludwig-Guttmann-Str. 13, 67071 Ludwigshafen, Germany; Heidelberg University, Grabengasse 1, D-69117 Heidelberg, Germany
| | - Sven Y Vetter
- BG Klinik Ludwigshafen, Department of Orthopedics and Trauma Surgery, Research group Medical Imaging and Navigation in Trauma and Orthopedic Surgery (MINTOS), BG Klinik Ludwigshafen, Ludwig-Guttmann-Str. 13, 67071 Ludwigshafen, Germany; Heidelberg University, Grabengasse 1, D-69117 Heidelberg, Germany
| | - Jochen Franke
- Tauernklinikum, Paracelsusstraße 8, A-5700 Zell am See, Austria
| | - Paul A Gruetzner
- BG Klinik Ludwigshafen, Department of Orthopedics and Trauma Surgery, Research group Medical Imaging and Navigation in Trauma and Orthopedic Surgery (MINTOS), BG Klinik Ludwigshafen, Ludwig-Guttmann-Str. 13, 67071 Ludwigshafen, Germany; Heidelberg University, Grabengasse 1, D-69117 Heidelberg, Germany
| | - Benedict Swartman
- BG Klinik Ludwigshafen, Department of Orthopedics and Trauma Surgery, Research group Medical Imaging and Navigation in Trauma and Orthopedic Surgery (MINTOS), BG Klinik Ludwigshafen, Ludwig-Guttmann-Str. 13, 67071 Ludwigshafen, Germany; Heidelberg University, Grabengasse 1, D-69117 Heidelberg, Germany.
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Qiao N, Villemure I, Aubin CE. A novel method for assigning bone material properties to a comprehensive patient-specific pelvic finite element model using biplanar multi-energy radiographs. Comput Methods Biomech Biomed Engin 2024; 27:2377-2388. [PMID: 37975562 DOI: 10.1080/10255842.2023.2280764] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 11/01/2023] [Accepted: 11/02/2023] [Indexed: 11/19/2023]
Abstract
The increasing prevalence of adult spinal deformity requires long spino-pelvic instrumentation, but pelvic fixation faces challenges due to distal forces and reduced bone quality. Bi-planar multi-energy X-rays (BMEX) were used to develop a patient-specific finite element model (FEM) for evaluating pelvic fixation. Calibration involved 10 patients, and an 81-year-old female test case was used for FEM customization and pullout simulation validation. Calibration yielded a root mean square error of 74.7 mg/cm3 for HU. The simulation accurately replicated the experimental pullout test with a force of 565 N, highlighting the method's potential for optimizing biomechanical performance for pelvic fixation.
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Affiliation(s)
- Ningxin Qiao
- Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, Canada
- Sainte-Justine University Hospital Center, Montreal, Canada
| | - Isabelle Villemure
- Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, Canada
- Sainte-Justine University Hospital Center, Montreal, Canada
| | - Carl-Eric Aubin
- Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, Canada
- Sainte-Justine University Hospital Center, Montreal, Canada
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Chayer M, Phan P, Arnoux PJ, Wang Z, Aubin CÉ. Biomechanical modelling of indirect decompression in oblique lumbar intervertebral fusions - A finite element study. Clin Biomech (Bristol, Avon) 2024; 120:106352. [PMID: 39321613 DOI: 10.1016/j.clinbiomech.2024.106352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2024] [Revised: 09/14/2024] [Accepted: 09/18/2024] [Indexed: 09/27/2024]
Abstract
BACKGROUND Oblique lumbar intervertebral fusion aims to decompress spinal nerves via an interbody fusion cage, but the optimal surgical strategy, including implant selection for specific patient characteristics, remains unclear. A biomechanical model was developed to assess how pathophysiological characteristics and instrumentation impact spinal realignment, indirect decompression, and cage subsidence risk. METHODS A finite element model of the L4-L5 segment was derived from a validated asymptomatic T1-S1 spine model. Five cases of grade I spondylolisthesis with normal or osteoporotic bone densities and initial disc heights of 4.3 to 8.3 mm were simulated. Oblique lumbar intervertebral fusion with cage heights of 10, 12, and 14 mm (12° lordosis) was examined. Postoperative changes in disc height, foraminal and spinal canal dimensions, segmental lordosis, and vertebral slip were assessed. Vertebral stresses and displacements under 10 Nm flexion and 400 N gravitational load were compared between stand-alone constructs and bilateral pedicle screw fixation using rods of 4.75, 5.5, and 6 mm diameters. FINDINGS Oblique lumbar intervertebral fusion significantly improved postoperative disc height, foraminal and spinal canal dimensions, with the greatest enhancements observed with 14 mm cages. Bilateral pedicle screw fixation markedly reduced cortical endplate stresses and displacements compared to stand-alone constructs, with added benefits from larger rod diameters. Low bone density increased displacements by 63 %. INTERPRETATION Thicker cages achieve better decompression but increase subsidence risk. Bilateral pedicle screw fixation with 6 mm rods minimizes endplate stresses and displacements, especially in osteoporotic cases. Future research will validate these findings and explore the model's potential for surgical planning.
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Affiliation(s)
- Mathieu Chayer
- Institute of Biomedical Engineering, Polytechnique Montréal, PO Box 6079, Montreal, QC H3C 3A7, Canada; Sainte-Justine University Hospital Center, Montreal, Canada
| | - Philippe Phan
- Department of Surgery, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Pierre-Jean Arnoux
- Laboratoire de Biomécanique Appliquée, Aix-Marseille Université/Université Gustave Eiffel, Marseille, France
| | - Zhi Wang
- Centre Hospitalier de l'Université de Montréal, Montreal, Canada; Department of Surgery, Faculty of Medicine, Université de Montréal, Montreal, Canada
| | - Carl-Éric Aubin
- Institute of Biomedical Engineering, Polytechnique Montréal, PO Box 6079, Montreal, QC H3C 3A7, Canada; Sainte-Justine University Hospital Center, Montreal, Canada; Department of Surgery, Faculty of Medicine, Université de Montréal, Montreal, Canada.
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Rouyin A, Nazemi H, Arjmand N, Einafshar MJ. Effect of pedicle screw misplacement on the pull-out strength using personalized finite element modeling. Comput Biol Med 2024; 183:109290. [PMID: 39427427 DOI: 10.1016/j.compbiomed.2024.109290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2024] [Revised: 09/12/2024] [Accepted: 10/15/2024] [Indexed: 10/22/2024]
Abstract
Intraoperative misplacement of vertebral pedicle screws is prevalent. While a pedicle screw misplacement of up to 4 mm is often considered safe by clinical standards, this may reduce the pull-out strength thereby increasing the risk of postoperative screw loosening. This study aimed to compare the pull-out strength of ideally-placed and misplaced pedicle screws via personalized finite element (FE) modeling simulations. Three-dimensional FE models to simulate pull-out tests of pedicle screws were constructed. Vertebral geometries and material properties were both determined based on computed tomography images from lumbar spine (L1-L5) of a 29-year-old healthy male individual. Pedicle screws were bilaterally placed under four conditions: ideal placement (no cortex perforation) as well as minor medial, minor lateral, and severe lateral misplacements causing cortex perforations. Minor and severe misplacements corresponded to, respectively, grades C and D of the Gertzbein classification. After meshing and voxel-based vertebral material assignments based on two distinct mappings from literature, pull-out strengths were estimated by considering a strain-based damage model to accurately simulate bone fractures. Results indicated that the mean of FE-predicted pull-out forces for ideally-placed screws (1583 and 2412 N for material mappings 1 and 2, respectively) was within the range of previous experimental data (ranging from 1016 to 2443 N) thus confirming the model validation. The mean of all pull-out forces for each misplaced screw group was significantly smaller (p < 0.05) than that of the ideally-placed screws, e.g., 20 % for minor medial, 22 % for minor lateral, and 37 % for severe lateral misplacements. These findings indicated that even clinically-acceptable screw misplacements (up to 4 mm) could significantly reduce the pull-out strengths of pedicle screws thus imposing higher risk of postoperative screw loosening. To avoid these common screw misplacements, the use of advanced approaches for pedicle screw placements appears to be imperative.
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Affiliation(s)
- A Rouyin
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
| | - H Nazemi
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
| | - N Arjmand
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.
| | - M J Einafshar
- Department of Material and Production, Aalborg University, Aalborg, Denmark
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Rouyin A, Einafshar MM, Arjmand N. A novel personalized homogenous finite element model to predict the pull-out strength of cancellous bone screws. J Orthop Surg Res 2024; 19:732. [PMID: 39506782 PMCID: PMC11542241 DOI: 10.1186/s13018-024-05169-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2024] [Accepted: 10/13/2024] [Indexed: 11/08/2024] Open
Abstract
BACKGROUND Orthopedic surgeries often involve the insertion of bone screws for various fixation systems. The risk of postoperative screw loosening is usually assessed through experimental or finite element (FE) evaluations of the screw pull-out strength. FE simulations are based on either personalized complex but accurate heterogeneous modeling or non-personalized simple but relatively less accurate homogeneous modeling. This study aimed to develop and validate a novel personalized computed tomography (CT)-based homogeneous FE simulation approach to predict the pull-out force of cancellous bone screws. METHODS Twenty FE simulations of L1-L5 vertebral screw pull-out tests were conducted, i.e., 10 heterogeneous and 10 homogenous models. Screws were inserted into the lower-middle region of vertebrae. In our novel homogeneous model, the region around approximately twice the diameter of the screw was used as a bone material reference volume. Subsequently, the overall material property of this region was homogeneously attributed to the entire vertebra, and pull-out simulations were conducted. RESULTS The mean error of the predicted pull-out forces by our novel homogenous simulations was ~ 7.9% with respect to our heterogeneous model. When solely the cancellous bone was involved during the pull-out process (i.e., for L1, L2, and L3 vertebral bodies whose cortical bone in the inferior region is thin), the novel homogenous model yielded small mean error of < 6.0%. This error, however, increased to ~ 11% when the screw got involved to the cortical bone (for L4 and L5 vertebrae whose cortical bone in the inferior region is thick). CONCLUSION The proposed personalized CT-based homogenous model was highly accurate in estimating the pull-out force especially when only the cancellous bone was involved with the screw.
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Affiliation(s)
- Alireza Rouyin
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, 11155-9567, Iran
| | | | - Navid Arjmand
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, 11155-9567, Iran.
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Ma L, Yan Y, Wang X, Wang S, Li F, Zhang K, Fan X, Zhong H, Lou X, Wu X, Xue Y, Wang Y, He L, Yan R, Chen W. Biomechanical evaluation and optimal design of a pedicle screw with double bent rods internal fixation system based on PE-PLIF fusion. Comput Methods Biomech Biomed Engin 2024; 27:1448-1459. [PMID: 37652157 DOI: 10.1080/10255842.2023.2245517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 07/20/2023] [Accepted: 07/31/2023] [Indexed: 09/02/2023]
Abstract
Problems, such as broken screws, broken rods, and cage subsidence after clinical spinal fusion surgery affect the success rate of fusion surgery and the fixation effect of fusion segments, and these problems still affect the treatment and postoperative recovery of patients. In this study, we used the biomechanical finite element analysis method to analyze and study the fixation effect of three kinds of spinal internal fixation systems on L4-L5 lumbar spine segments in percutaneous endoscopic posterior lumbar interbody fusion (PE-PLIF). The three different fixation systems compared in this study include bilateral pedicle screw fixation (M1); bilateral pedicle screw with cross-link fixation (M2); bilateral pedicle screws with double bent rods fixation (M3). The internal fixation systems with different structures were analyzed with the help of Hypermesh, and Abaqus. It was found that the internal fixation system with double bent rods reduced screw stresses by 23.8 and 22.2% in right and left axial rotation than the traditional bilateral pedicle screw system, while titanium rod stresses were reduced by 9.6, 3.7, 9.6, and 2.9% in flexion, left and right lateral bending, and right axial rotation, respectively, and L5 upper endplate stresses were reduced by 35.5, 18.9, 38.4, 10.2, and 48.3% in flexion, left and right lateral bending, and left and right axial rotation, respectively. The spinal range of motion (ROM) of the M3 internal fixation system was less than that of the M1 and M2 internal fixation systems in left lateral bending, left lateral rotation, and right axial rotation, and the intact vertebral ROM was reduced by 93.7, 94.9, and 90.9%, respectively. The double bent rod structure of the spinal internal fixation system has better biomechanical properties, which can effectively reduce the risk of screw breakage, loosening, cage subsidence, and endplate collapse after fusion surgery.
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Affiliation(s)
- Lei Ma
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, China
| | - Yang Yan
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, China
| | - Xiyu Wang
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, China
| | - Songyuan Wang
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, China
| | - Feng Li
- Department of Spine Surgery, Weifang People's Hospital, Weifang, China
| | - Kai Zhang
- Huajin Orthopaedic Hospital, Taiyuan, China
| | - Xuanze Fan
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, China
| | - Hao Zhong
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, China
| | - Xinqi Lou
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, China
| | - Xiaogang Wu
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, China
| | - Yanru Xue
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, China
| | - Yanqin Wang
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, China
| | - Liming He
- Shanxi Bethune Hospital, Shanxi Academy of Medical Sciences, Tongji Shanxi Hospital, Third Hospital of Shanxi Medical University, Taiyuan, China
| | - Ruizhong Yan
- Taiyuan Central Hospital of Shanxi Medical University, Taiyuan, China
| | - Weiyi Chen
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, China
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11
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Safahieh AH, Nazemi H, Arjmand N, Azimi P, Khalaf K. Design, fabrication, and evaluation of single- and multi-level 3D-printed non-covering cervical spinal fusion surgery templates. Front Bioeng Biotechnol 2024; 12:1416872. [PMID: 39070162 PMCID: PMC11272535 DOI: 10.3389/fbioe.2024.1416872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2024] [Accepted: 06/17/2024] [Indexed: 07/30/2024] Open
Abstract
Background Cervical spinal fusion surgeries require accurate placement of the pedicle screws. Any misplacement/misalignment of these screws may lead to injuries to the spinal cord, arteries and other organs. Template guides have emerged as accurate and cost-effective tools for the safe and rapid insertions of pedicle screws. Questions/Purposes Novel patient-specific single- and multi-level non-covering templates for cervical pedicle screw insertions were designed, 3D-printed, and evaluated. Methods CT scans of two patients were acquired to reconstruct their 3D spine model. Two sets of single-level (C3-C7) and multi-level (C4-C6) templates were designed and 3D-printed. Pedicle screws were inserted into the 3D-printed vertebrae by free-hand and guided techniques. For single-level templates, a total of 40 screws (2 patients × 5 vertebrae × 2 methods × 2 screws) and for multi-level templates 24 screws (2 patients × 3 vertebrae × 2 methods × 2 screws) were inserted by an experienced surgeon. Postoperative CT images were acquired to measure the errors of the entry point, 3D angle, as well as axial and sagittal plane angles of the inserted screws as compared to the initial pre-surgery designs. Accuracy of free-hand and guided screw insertions, as well as those of the single- and multi-level guides, were also compared using paired t-tests. Results Despite the minimal removal of soft tissues, the 3D-printed templates had acceptable stability on the vertebrae during drillings and their utilization led to statistically significant reductions in all error variables. The mean error of entry point decreased from 3.02 mm (free-hand) to 0.29 mm (guided) using the single-level templates and from 5.7 mm to 0.76 mm using the multi-level templates. The percentage reduction in mean of other error variables for, respectively, single- and multi-level templates were as follows: axial plane angle: 72% and 87%, sagittal plane angle: 56% and 78%, and 3D angle: 67% and 83%. The error variables for the multi-level templates generally exceeded those of the single-level templates. The use of single- and multi-level templates also considerably reduced the duration of pedicle screw placements. Conclusion The novel single- and multi-level non-covering templates are valuable tools for the accurate placement of cervical pedicle screws.
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Affiliation(s)
- A. H. Safahieh
- Mechanical Engineering Department, Sharif University of Technology, Tehran, Iran
| | - H. Nazemi
- Mechanical Engineering Department, Sharif University of Technology, Tehran, Iran
| | - N. Arjmand
- Mechanical Engineering Department, Sharif University of Technology, Tehran, Iran
| | - P. Azimi
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - K. Khalaf
- Department of Biomedical Engineering and Health Engineering Innovation Center, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
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Miyashita T, Kato K, Yunde A, Ataka H, Tanno T. Comparison of facet fusion rates and clinical outcomes between cortical bone trajectory screw and percutaneous pedicle screw fixation for degenerative lumbar spondylolisthesis. Spine J 2024; 24:1202-1210. [PMID: 38437917 DOI: 10.1016/j.spinee.2024.02.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 02/16/2024] [Accepted: 02/25/2024] [Indexed: 03/06/2024]
Abstract
BACKGROUND CONTEXT Cortical bone trajectory (CBT) screws have been introduced as an alternative technique for pedicle screw (PS) insertion because they have greater contact with the cortex and a greater uniaxial pullout load than traditional PS. CBT screwing can also minimize muscle dissection. However, CBT screws and traditional PSs have not yet been compared in terms of fusion rates and clinical outcomes for particular operative procedures. PURPOSE This study aimed to assess the fusion rate and clinical outcomes of facet fusion (FF) fixed with CBT screws (CBT-FF) and to compare them with those of FF fixed with percutaneous PS (PPS-FF). STUDY DESIGN Retrospective study. PATIENT SAMPLE Records of 68 patients who underwent CBT-FF for single-level degenerative lumbar spondylolisthesis (DLS) with at least 1 year of follow-up were retrospectively reviewed. The control group comprised 143 patients who underwent PPS-FF under the same conditions. OUTCOME MEASURES Computed tomography was performed to confirm fusion. Therapeutic effectiveness was assessed as a clinical outcome using the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ), Roland-Morris Disability Questionnaire (RMDQ), and visual analog scale (VAS) preoperatively and 1 year postoperatively. The rate of revision surgery was also calculated. Intraoperative blood loss was measured. METHODS Fusion rate, clinical outcomes, revision surgery rate, and intraoperative blood loss of CBT-FF and PPS-FF were compared. RESULTS The CBT-FF and PPS-FF fusion rates were 91.2% and 90.1%, respectively. The JOABPEQ category scores demonstrated therapeutic effectiveness in 74.5% and 77.1% of the patients for low back pain; the corresponding proportions for walking ability were 84.7% and 89.3%, respectively. No significant differences in therapeutic effectiveness were observed for any category, including the RMDQ and VAS scores for buttock and lower limb pain. Three patients required revision surgery for adjacent segment disease between 6 months and 3.5 years after CBT-FF (revision surgery rate, 4.4%), whereas the revision surgery rate for PPS-FF was 6.3% (9/143 cases). Average intraoperative blood loss was significantly less in the CBT-FF group than in the PPS-FF group. CONCLUSIONS Both procedures were equally useful in terms of fusion rate and clinical outcomes for DLS management.
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Affiliation(s)
- Tomohiro Miyashita
- Spine Center, Matsudo City General Hospital, 993-1 Sendabori, Matsudo, Chiba, 270-2296, Japan.
| | - Kei Kato
- Spine Center, Matsudo City General Hospital, 993-1 Sendabori, Matsudo, Chiba, 270-2296, Japan
| | - Atsushi Yunde
- Spine Center, Matsudo City General Hospital, 993-1 Sendabori, Matsudo, Chiba, 270-2296, Japan
| | - Hiromi Ataka
- Spine Center, Matsudo Orthopaedic Hospital, 1-161, Asahi-cho, Matsudo, Chiba, 271-0043, Japan
| | - Takaaki Tanno
- Spine Center, Matsudo Orthopaedic Hospital, 1-161, Asahi-cho, Matsudo, Chiba, 271-0043, Japan
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Nourissat G, Housset V, Daudet JM, Fradet L, Bianco RJ, Srikumaran U. Finite element analysis part 1 of 2: Influence of short stem implant polyethylene configuration on glenohumeral joint biomechanics. J Exp Orthop 2024; 11:e70000. [PMID: 39301205 PMCID: PMC11411371 DOI: 10.1002/jeo2.70000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2023] [Revised: 07/06/2024] [Accepted: 07/20/2024] [Indexed: 09/22/2024] Open
Abstract
Purpose Stress shielding in short-stem arthroplasty can cause critical metaphyseal bone loss. If the size and shape of the humeral shaft are important factors, it is unknown whether the shape of the polyethylene component in reverse shoulder arthroplasty (RSA) affects bone stress around or within the stem. We explored the impact of polyethylene shape on humeral and scapular stress distribution using a finite element model. Methods We developed a shoulder-specific finite element model. A defined set of muscle forces was applied to simulate movements. An intact rotator cuff state and a superior deficient rotator cuff state were modelled. We used the FX V135 short stem in three conditions: total shoulder arthroplasty (TSA), and RSA with symmetrical and asymmetrical polyethylene (145°/135°). We measured biomechanical markers related to bone stress for different implant sizes. Joint kinematics and the mechanical behaviour of the implant were compared. Results Rupture of the supraspinatus muscle produced a functionally limited shoulder. The placement of an anatomic TSA with an intact rotator cuff restored function similar to that of a healthy shoulder. RSA in the rotator cuff-deficient shoulder restored function regardless of stem size and polyethylene shape. While stem size had an impact on the stress distribution in the bone and implant, it did not show significant potential for increasing or decreasing overall stress. For the same stem, stress distribution at the humerus is different between TSA and RSA. Polyethylene shape did not alter the transmission of stress to the bone in RSA. Asymmetric polyethylene produced a greater abduction range of motion. Conclusions In terms of bone stress distribution, smaller stems seemed more appropriate for TSA, while larger stems may be more appropriate for RSA. Polyethylene shape resulted in different ranges of motion but did not influence bone stress. Level of Evidence Diagnostic Tests or Criteria; Level IV.
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Affiliation(s)
| | - Victor Housset
- Groupe Maussins Clinique Maussins Nollet-Ramsay Santé Paris France
- Hôpital Henri Mondor Université Paris-Est Créteil Créteil France
| | | | | | | | - Uma Srikumaran
- Department of Orthopedic Surgery The Johns Hopkins University Baltimore Maryland USA
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Housset V, Srikumaran U, Daudet JM, Fradet L, Bianco RJ, Nourissat G. Finite element analysis part 2 of 2: Glenohumeral bone stress distribution depends on implant configuration for anatomic and reverse stemless shoulder implants. J Exp Orthop 2024; 11:e70001. [PMID: 39301206 PMCID: PMC11411269 DOI: 10.1002/jeo2.70001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2023] [Revised: 07/06/2024] [Accepted: 07/20/2024] [Indexed: 09/22/2024] Open
Abstract
Purpose Our purpose was to quantify stresses in the bone surrounding stemless implants in various configurations. Methods A detailed finite element model of the glenohumeral joint was used to simulate abduction kinematics before and after arthroplasty and to measure bone stresses around the implants. Two digital patients were simulated: one healthy and one with supraspinatus muscle impairment (deficiency). Two anatomic total shoulder arthroplasty (TSA) configurations were placed in a 135° cutting plane. Two reverse shoulder arthroplasty (RSA) configurations with cutting angles of 135° and 145° were simulated with asymmetrical and symmetrical polyethylene cups, respectively, to obtain humeral neck-shaft angles of 145°. Results Compared with preoperative models, TSA preserved and RSA restored abduction kinematics. The bone mechanical stresses were located mainly around the central stud of the TSA and were more peripheral to the RSA humeral components. The RSA configuration with the 145° cutting angle and symmetrical cup generated the lowest maximal bone stress and bone volume involvement. Stresses in the scapular cortical bone were highest in the supraspinatus fossa for TSA and the crest of the acromion for RSA. Conclusion Early stability and glenohumeral bone stress change with implant configuration and should not be extrapolated from anatomic clinical data to reverse configurations. Level of Evidence Diagnostic tests or criteria; Level IV.
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Affiliation(s)
- Victor Housset
- Hôpital Henri-Mondor, Université Paris-Est Créteil Créteil France
- Groupe Maussins, Clinique Maussins Nollete-Ramsay Santé Paris France
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Qiao N, Villemure I, Wang Z, Petit Y, Aubin CE. Optimization of S2-alar-iliac screw (S2AI) fixation in adult spine deformity using a comprehensive genetic algorithm and finite element model personalized to patient geometry and bone mechanical properties. Spine Deform 2024; 12:595-602. [PMID: 38451404 DOI: 10.1007/s43390-024-00833-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Accepted: 01/20/2024] [Indexed: 03/08/2024]
Abstract
PURPOSE To optimize the biomechanical performance of S2AI screw fixation using a genetic algorithm (GA) and patient-specific finite element analysis integrating bone mechanical properties. METHODS Patient-specific pelvic finite element models (FEM), including one normal and one osteoporotic model, were created from bi-planar multi-energy X-rays (BMEXs). The genetic algorithm (GA) optimized screw parameters based on bone mass quality (BM method) while a comparative optimization method maximized the screw corridor radius (GEO method). Biomechanical performance was evaluated through simulations, comparing both methods using pullout and toggle tests. RESULTS The optimal screw trajectory using the BM method was more lateral and caudal with insertion angles ranging from 49° to 66° (sagittal plane) and 29° to 35° (transverse plane). In comparison, the GEO method had ranges of 44° to 54° and 24° to 30° respectively. Pullout forces (PF) using the BM method ranged from 5 to 18.4 kN, which were 2.4 times higher than the GEO method (2.1-7.7 kN). Toggle loading generated failure forces between 0.8 and 10.1 kN (BM method) and 0.9-2.9 kN (GEO method). The bone mass surrounding the screw representing the fitness score and PF of the osteoporotic case were correlated (R2 > 0.8). CONCLUSION Our study proposed a patient-specific FEM to optimize the S2AI screw size and trajectory using a robust BM approach with GA. This approach considers surgical constraints and consistently improves fixation performance.
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Affiliation(s)
- Ningxin Qiao
- Institute of Biomedical Engineering, Polytechnique Montréal, PO Box 6079, Downtown station, Montreal, QC H3C 3A7, Canada
- Sainte-Justine University Hospital Center, Montreal, Canada
| | - Isabelle Villemure
- Institute of Biomedical Engineering, Polytechnique Montréal, PO Box 6079, Downtown station, Montreal, QC H3C 3A7, Canada
- Sainte-Justine University Hospital Center, Montreal, Canada
| | - Zhi Wang
- Centre Hospitalier de l'Université de Montréal, Montreal, Canada
- Department of Surgery, Faculty of Medicine, Université de Montréal, Montreal, Canada
| | - Yvan Petit
- Department of Mechanical Engineering, Ecole de Technologie Supérieure, Montreal, Canada
| | - Carl-Eric Aubin
- Institute of Biomedical Engineering, Polytechnique Montréal, PO Box 6079, Downtown station, Montreal, QC H3C 3A7, Canada.
- Sainte-Justine University Hospital Center, Montreal, Canada.
- Department of Surgery, Faculty of Medicine, Université de Montréal, Montreal, Canada.
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Matsukawa K, Konomi T, Matsubayashi K, Yamane J, Yato Y. Influence of Pedicle Screw Insertion Depth on Posterior Lumbar Interbody Fusion: Radiological Significance of Deeper Screw Placement. Global Spine J 2024; 14:470-477. [PMID: 35713986 PMCID: PMC10802553 DOI: 10.1177/21925682221110142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
STUDY DESIGN Retrospective case series. OBJECTIVES To investigate the influence of screw size on achieving bone fusion in posterior lumbar interbody fusion (PLIF). METHODS In total, 137 consecutive patients with L4 degenerative spondylolisthesis who underwent single-level PLIF at L4-L5 were evaluated. Factors investigated for their contribution to bone fusion included: 1) age, 2) sex, 3) body mass index, 4) bone mineral density, 5) intervertebral mobility, 6) screw diameter, 7) screw length, 8) screw fitness in the pedicle (%fill), 9) screw depth in the vertebra (%depth), 10) screw angle, 11) facetectomy, 12) crosslink connector, and 13) cage material. RESULTS Bone fusion was confirmed in 88.2% of patients. The comparison between fusion (+) and fusion (-) groups showed no significant differences in screw size. The %fill and %length were significantly greater in the fusion (+) group than in the fusion (-) group (%fill: 58.5% ± 7.5% vs 52.3% ± 7.3%, respectively, P = .005; %depth: 59.8% ± 9.7% vs 50.3% ± 13.8%, respectively, P = .025). Multivariate logistic regression analysis revealed that %fill (odds ratio [OR]= 1.11, P = .025) and %depth (OR = 1.09, P = .003) were significant independent factors affecting bone fusion. Receiver operating characteristic curve analyses identified a %fill of 60.0% and a %depth of 54.2% as optimal cutoff values for achieving bone fusion. CONCLUSIONS Screw size should be determined based on the screw fitness in the pedicle (%fill > 60%) and screw insertion depth in the vertebral body (%depth > 54.2%) according to individual vertebral anatomy in L4-L5 PLIF.
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Affiliation(s)
- Keitaro Matsukawa
- Department of Orthopaedic Surgery, National Hospital Organization, Murayama Medical Center, Musashimurayama, Japan
| | - Tsunehiko Konomi
- Department of Orthopaedic Surgery, National Hospital Organization, Murayama Medical Center, Musashimurayama, Japan
| | - Kohei Matsubayashi
- Department of Orthopaedic Surgery, National Hospital Organization, Murayama Medical Center, Musashimurayama, Japan
| | - Junichi Yamane
- Department of Orthopaedic Surgery, National Hospital Organization, Murayama Medical Center, Musashimurayama, Japan
| | - Yoshiyuki Yato
- Department of Orthopaedic Surgery, National Hospital Organization, Murayama Medical Center, Musashimurayama, Japan
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Hwang YH, Ha BJ, Kim HC, Lee BH, Park JY, Chin DK, Yi S. A Propensity Score-Matched Cohort Study Comparing 3 Different Spine Pedicle Screw Fixation Methods: Freehand, Fluoroscopy-Guided, and Robot-Assisted Techniques. Neurospine 2024; 21:83-94. [PMID: 38569633 PMCID: PMC10992644 DOI: 10.14245/ns.2448036.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 02/14/2024] [Accepted: 02/18/2024] [Indexed: 04/05/2024] Open
Abstract
OBJECTIVE This study aimed to compare the accuracy of robotic spine surgery and conventional pedicle screw fixation in lumbar degenerative disease. We evaluated clinical and radiological outcomes to demonstrate the noninferiority of robotic surgery. METHODS This study employed propensity score matching and included 3 groups: robot-assisted mini-open posterior lumbar interbody fusion (PLIF) (robotic surgery, RS), c-arm guided minimally invasive surgery transforaminal lumbar interbody fusion (C-arm guidance, CG), and freehand open PLIF (free of guidance, FG) (54 patients each). The mean follow-up period was 2.2 years. The preoperative spine condition was considered. Accuracy was evaluated using the Gertzbein-Robbins scale (GRS score) and Babu classification (Babu score). Radiological outcomes included adjacent segmental disease (ASD) and mechanical failure. Clinical outcomes were assessed based on the visual analogue scale, Oswestry Disability Index, 36-item Short Form health survey, and clinical ASD rate. RESULTS Accuracy was higher in the RS group (p < 0.01) than in other groups. The GRS score was lower in the CG group, whereas the Babu score was lower in the FG group compared with the RS group. No significant differences were observed in radiological and clinical outcomes among the 3 groups. Regression analysis identified preoperative facet degeneration, GRS and Babu scores as significant variables for radiological and clinical ASD. Mechanical failure was influenced by the GRS score and patients' age. CONCLUSION This study showed the superior accuracy of robotic spine surgery compared with conventional techniques. When combined with minimally invasive surgery, robotic surgery is advantageous with reduced ligament and muscle damage associated with traditional open procedures.
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Affiliation(s)
- Yoon Ha Hwang
- Department of Neurosurgery, Spine and Spinal Cord Institute, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Byeong-Jin Ha
- Department of Neurosurgery, Spine and Spinal Cord Institute, Yonsei University College of Medicine, Seoul, Korea
- Department of Neurosurgery, Hanyang University Guri Hospital, Guri, Korea
| | - Hyung Cheol Kim
- Department of Neurosurgery, Spine and Spinal Cord Institute, Yonsei University College of Medicine, Seoul, Korea
- Department of Neurosurgery, Bundang Jesaeng General Hospital, Seongnam, Korea
| | - Byung Ho Lee
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, Seoul, Korea
| | - Jeong-Yoon Park
- Department of Neurosurgery, Spine and Spinal Cord Institute, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Dong-Kyu Chin
- Department of Neurosurgery, Spine and Spinal Cord Institute, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Seong Yi
- Department of Neurosurgery, Spine and Spinal Cord Institute, Yonsei University College of Medicine, Seoul, Korea
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Yang JX, Luo L, Liu JH, Wang N, Xi ZP, Li JC. Incomplete insertion of pedicle screws triggers a higher biomechanical risk of screw loosening: mechanical tests and corresponding numerical simulations. Front Bioeng Biotechnol 2024; 11:1282512. [PMID: 38260754 PMCID: PMC10800439 DOI: 10.3389/fbioe.2023.1282512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 12/11/2023] [Indexed: 01/24/2024] Open
Abstract
Screw loosening is a widely reported issue after spinal screw fixation and triggers several complications. Biomechanical deterioration initially causes screw loosening. Studies have shown that incomplete insertion of pedicle screws increases the risk of screw breakage by deteriorating the local mechanical environment. However, whether this change has a biomechanical effect on the risk of screw loosening has not been determined. This study conducted comprehensive biomechanical research using polyurethane foam mechanical tests and corresponding numerical simulations to verify this topic. Pedicle screw-fixed polyurethane foam models with screws with four different insertion depths were constructed, and the screw anchoring ability of different models was verified by toggle tests with alternating and constant loads. Moreover, the stress distribution of screw and bone-screw interfaces in different models was computed in corresponding numerical mechanical models. Mechanical tests presented better screw anchoring ability with deeper screw insertion, but parameters presented no significant difference between groups with complete thread insertion. Correspondingly, higher stress values can be recorded in the model without complete thread insertion; the difference in stress values between models with complete thread insertion was relatively slight. Therefore, incomplete thread insertion triggers local stress concentration and the corresponding risk of screw loosening; completely inserting threads could effectively alleviate local stress concentration and result in the prevention of screw loosening.
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Affiliation(s)
- Jie-Xiang Yang
- Department of Orthopedics, The Affiliated Traditional Chinese Medicine Hospital, Southwest Medical University, Luzhou, China
- Luzhou Key Laboratory of Orthopedic Disorders, Southwest Medical University, Luzhou, Sichuan, China
| | - Lin Luo
- Department of Orthopedics, The Affiliated Traditional Chinese Medicine Hospital, Southwest Medical University, Luzhou, China
- Luzhou Key Laboratory of Orthopedic Disorders, Southwest Medical University, Luzhou, Sichuan, China
| | - Jin-Hui Liu
- Sichuan Provincial Laboratory of Orthopaedic Engineering, Department of Bone and Joint Surgery, Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, China
| | - Nan Wang
- Department of Orthopedics, Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China
| | - Zhi-Peng Xi
- Department of Orthopedics, Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China
| | - Jing-Chi Li
- Department of Orthopedics, The Affiliated Traditional Chinese Medicine Hospital, Southwest Medical University, Luzhou, China
- Luzhou Key Laboratory of Orthopedic Disorders, Southwest Medical University, Luzhou, Sichuan, China
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Solitro GF, Welborn MC, Mehta AI, Amirouche F. How to Optimize Pedicle Screw Parameters for the Thoracic Spine? A Biomechanical and Finite Element Method Study. Global Spine J 2024; 14:187-194. [PMID: 35499547 PMCID: PMC10676166 DOI: 10.1177/21925682221099470] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
STUDY DESIGN Pedicle screw study. OBJECTIVE The selection of pedicle screw parameters usually involves the surgeon's analysis of preoperative CT imaging along with anatomical landmarks and tactile examination. However, there is minimal consensus on a standardized guideline for selection methods on pedicle screws. We aimed to determine the effects of thoracic screw diameter to pedicle width on pullout strength determined by cortical bone purchase. METHODS Biomechanical study performed with human cadaveric thoracic vertebrae and experimentally validated three-dimensional finite element model instrumented with pedicle screws of various diameters. We used a variable (SD/PW) ratio to express the screw selection. We hypothesized a positive correlation between the pullout load determined by the bone purchase and the SD/PW. This relationship was first investigated in a validated finite element model considering bone purchase related to the strength of an upper thoracic vertebra. Then, the correlation to the entire spine is evaluated. RESULTS The failure load ranged from 371.3 to 1601.0 N, respectively, for 3 and 6 mm screws. The determinant coefficient was increased to R2=.421 when a linear relationship between pullout load and the SD/PW ratio was used. The peak loads of 1216 and 1288N were found for an SD/PW ratio of .83. CONCLUSION We have found that the screw pullout load is more correlated to SD/PW than other pedicle measures for a maximized SD/PW ratio of .83. This particular value should be considered the upper limit of the indicated SD/PW ratio and a means to determine the optimal screw diameter to enhance pullout strength.
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Affiliation(s)
| | - Michelle C. Welborn
- Department of Neurosurgery, University of Illinois at Chicago, Chicago, Il, USA
| | - Ankit I. Mehta
- Department of Orthopaedic Surgery, NorthShore University HealthSystem, Evanston, Il, USA
| | - Farid Amirouche
- Department of Orthopaedics, Louisiana State University, Chicago, Il, USA
- College of Medicine, University of Illinois at Chicago, Chicago, Il, USA
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20
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Leblond L, Godio-Raboutet Y, Tomi F, Glard Y, La Greca R, Clement T, Evin M. Sliding on cortical shell: Biomechanical characterization of the vertebral cannulation for pedicle screw insertion. Clin Biomech (Bristol, Avon) 2023; 110:106102. [PMID: 37769380 DOI: 10.1016/j.clinbiomech.2023.106102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 09/14/2023] [Accepted: 09/20/2023] [Indexed: 09/30/2023]
Abstract
BACKGROUND Pedicular screws pull-out has been well studied unlike their insertion. A need for characterizing cannulation before pedicle screw implantation is highlighted in literature and offers promising prospects for future intra-operation instrumentation. A reliable cannulation protocol for ex-vivo testing in swine and cadaver vertebrae is presented in this work to predict extra pedicular perforation. METHODS An MTS Acumen 3 A/T electrodynamic device, with a tri-axis 3 kN Kistler load cell mounted on a surgical tool was used to reproduce surgeon's gesture by moving at a constant rotational speed of 10°/mm and performing a three-section test. Perforation of the pedicle's cortical shell was planned through a design of experiment on the surgical tool angle at the entry point. Samples were scanned before and after mechanical tests and reproducibility of the protocol was tested on synthetic foam. Computation of the angle between cannulation tool and pedicle cortical shell was performed as well as cannulation coefficient of each perforation section. FINDINGS A total of 68 pedicles were tested: 19 perforated and 21 non-perforated human pedicles, 17 perforated and 16 non-perforated swine pedicles. The reproducibility of the protocol for cannulation coefficient computation resulted in an intraclass correlation coefficient of 0.979. Cannulation coefficients results presented variability within spinal levels as well as between swine and human model. Correlation between bone density and cannulation coefficient was found significant (p < 0.005). Torque measurement was found to be the best predictor of perforation. Threshold of angle for prediction of perforation was found to be 21.7°. INTERPRETATION Characterizing pedicle cannulation enables to predict extra pedicular perforation. Influence of bone mineral density and patient-specific morphology on pedicle cannulation has been highlighted together with a comparison of swine and cadaver models.
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Affiliation(s)
| | | | - Florent Tomi
- Aix Marseille Univ. Univ Gustave Eiffel, LBA, Marseille, France
| | - Yann Glard
- Department of Paediatric Orthopaedics, Saint Joseph Hospital, Marseille, France
| | | | - Thomas Clement
- Aix Marseille Univ. Univ Gustave Eiffel, LBA, Marseille, France
| | - Morgane Evin
- Aix Marseille Univ. Univ Gustave Eiffel, LBA, Marseille, France.
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Ye YX, Huang DG, Hao DJ, Liu JY, Ji JJ, Guo JN. Screw Pullout Strength After Pedicle Screw Reposition: A Finite Element Analysis. Spine (Phila Pa 1976) 2023; 48:E382-E388. [PMID: 36541576 PMCID: PMC10602223 DOI: 10.1097/brs.0000000000004553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 10/13/2022] [Accepted: 10/14/2022] [Indexed: 12/24/2022]
Abstract
RESEARCH DESIGN Finite element analysis based on computed tomography images from the lumbar spine. OBJECTIVE Determined the pullout strength of unsatisfactorily placed screws and repositioned screws after unsatisfactory place in lumbar spine surgery. BACKGROUND Pedicle screws are widely used to stabilize the spinal vertebral body. Unsatisfactory screws could lead to surgical complications, and may need to be repositioned. Screw removal and reposition, however, may decrease pullout strength. METHODS We conducted a three-dimensional finite element analysis based on high-resolution computed tomography images from a 39-year-old healthy woman. Pullout strength was determined with the screw placed in different orientations at the same entry point (as selected by the Magerl method), as well as after removal and reposition. The material properties of the vertebral body and the screw were simulated by using grayscale values and verified data, respectively. A load along the screw axis was applied to the end of the screw to simulate the pullout. RESULTS The pullout strength was 1840.0 N with the Magerl method. For unsatisfactorily placed screws, the pullout strength was 1500.8 N at 20% overlap, 1609.6 N at 40% overlap, 1628.9 N at 60% overlap, and 1734.7 N at 80% overlap with the hypothetical screw path of the Magerl method. For repositioned screws, the pullout strength was 1763.6 N, with 20% overlap, 1728.3 N at 40% overlap, 1544.0 N at 60% overlap, and 1491.1 N at 80% overlap, with the original path. Comparison of repositioned screw with unsatisfactorily placed screw showed 14.04% decrease in pullout strength at 80% overlap, 5.21% decrease at 60% overlap, 7.37% increase at 40% overlap, and 17.51% increase at 20% overlap, with the screw path of the Magerl method. CONCLUSIONS Removal and reposition increased the pullout strength at 20% and 40% overlap, but decreased the pullout strength at 60% and 80% overlap. For clinical translation, we recommend removal and reposition of the screw when the overlap is in the range of 20% to 40% or less. In vitro specimen studies are needed to verify these preliminary findings.
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Affiliation(s)
- Yu-Xing Ye
- Department of Spine Surgery, Honghui Hospital, Xi’an Jiaotong University, Xi’an, Shaanxi, China
- Shaanxi Key Laboratory of Spine Bionic Treatment, Honghui Hospital, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Da-Geng Huang
- Department of Spine Surgery, Honghui Hospital, Xi’an Jiaotong University, Xi’an, Shaanxi, China
- Shaanxi Key Laboratory of Spine Bionic Treatment, Honghui Hospital, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Ding-Jun Hao
- Department of Spine Surgery, Honghui Hospital, Xi’an Jiaotong University, Xi’an, Shaanxi, China
- Shaanxi Key Laboratory of Spine Bionic Treatment, Honghui Hospital, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Jia-Yuan Liu
- Department of Spine Surgery, Honghui Hospital, Xi’an Jiaotong University, Xi’an, Shaanxi, China
- Shaanxi Key Laboratory of Spine Bionic Treatment, Honghui Hospital, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Jia-Jia Ji
- Department of Spine Surgery, Honghui Hospital, Xi’an Jiaotong University, Xi’an, Shaanxi, China
- Shaanxi Key Laboratory of Spine Bionic Treatment, Honghui Hospital, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Jin-Niu Guo
- Department of Spine Surgery, Honghui Hospital, Xi’an Jiaotong University, Xi’an, Shaanxi, China
- Shaanxi Key Laboratory of Spine Bionic Treatment, Honghui Hospital, Xi'an Jiaotong University, Xi'an, Shaanxi, China
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22
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Meynard A, Fréchède B, Pommier B, Mitton D, Barrey C. Biomechanical Comparison of Facet Versus Laminar C2 Screws. Neurosurgery 2023; 93:910-917. [PMID: 37057918 DOI: 10.1227/neu.0000000000002492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 02/14/2023] [Indexed: 04/15/2023] Open
Abstract
BACKGROUND Transpedicular or transisthmic screws for C2 instrumentation represent the gold standard; however, the anatomy is not always compatible (hypoplastic pedicles, procidentia of the vertebral artery). Laminar screws (LS) have been proposed as a rescue technique and recently, bicortical facet screws (FS). To date, the biomechanical property of FS remains unknown. OBJECTIVE To compare the pull-out resistance of bicortical facet (FS) vs laminar (LS) C2 screws. METHODS Thirty-two human cadaveric C2 vertebrae were screened by CT scan imaging and dual x-ray absorptiometry before receiving both techniques and were randomized according to side and sequence (FS or LS first). Screw positioning was validated using 2-dimensional x-rays. Sixty-four mechanical tests were performed using pure tensile loading along the axis of the screws until pull-out. Mean pull-out strengths were compared using paired tests, multivariate and survival analysis (Kaplan-Meier curves). RESULTS The morphometric data were consistent with previous studies. Over 64 tests, the mean pull-out strength of LS (707 ± 467 N) was significantly higher than that of FS (390 ± 230 N) ( P = .0004). Bone mineral density was weakly correlated with pull-out strength (r = 0.42 for FS and r = 0.3 for LS). Both techniques were mechanically equivalent for vertebrae in which intralaminar cortical grip was not achievable for LS. The mean pull-out strength for LS with laminar cortical grip (1071 ± 395 N) was significantly higher than that of LS without (423 ± 291 N) ( P < .0001). CONCLUSION Our results suggest that bicortical FS of C2 offer less mechanical resistance than LS.
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Affiliation(s)
- Alexandre Meynard
- Spine Surgery Unit, Hôpital Neurologique Pierre Wertheimer, Hospices Civils de Lyon, and University Claude Bernard of Lyon 1, Bron , France
- LBMC UMR T 9406, Univ Lyon, Univ Claude Bernard Lyon 1, Univ Gustave Eiffel, Lyon , France
| | - Bertrand Fréchède
- LBMC UMR T 9406, Univ Lyon, Univ Claude Bernard Lyon 1, Univ Gustave Eiffel, Lyon , France
| | - Benjamin Pommier
- Spine Surgery Unit, Hôpital Neurologique Pierre Wertheimer, Hospices Civils de Lyon, and University Claude Bernard of Lyon 1, Bron , France
| | - David Mitton
- LBMC UMR T 9406, Univ Lyon, Univ Claude Bernard Lyon 1, Univ Gustave Eiffel, Lyon , France
| | - Cédric Barrey
- Spine Surgery Unit, Hôpital Neurologique Pierre Wertheimer, Hospices Civils de Lyon, and University Claude Bernard of Lyon 1, Bron , France
- Institut de Biomécanique Humaine Georges Charpak, Arts et Métiers ParisTech, Paris , France
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Costăchescu B, Niculescu AG, Grumezescu AM, Teleanu DM. Screw Osteointegration-Increasing Biomechanical Resistance to Pull-Out Effect. MATERIALS (BASEL, SWITZERLAND) 2023; 16:5582. [PMID: 37629873 PMCID: PMC10456840 DOI: 10.3390/ma16165582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 08/03/2023] [Accepted: 08/09/2023] [Indexed: 08/27/2023]
Abstract
Spinal disorders cover a broad spectrum of pathologies and are among the most prevalent medical conditions. The management of these health issues was noted to be increasingly based on surgical interventions. Spinal fixation devices are often employed to improve surgery outcomes, increasing spinal stability, restoring structural integrity, and ensuring functionality. However, most of the currently used fixation tools are fabricated from materials with very different mechanical properties to native bone that are prone to pull-out effects or fail over time, requiring revision procedures. Solutions to these problems presently exploited in practice include the optimal selection of screw shape and size, modification of insertion trajectory, and utilization of bone cement to reinforce fixation constructs. Nevertheless, none of these methods are without risks and limitations. An alternative option to increasing biomechanical resistance to the pull-out effect is to tackle bone regenerative capacity and focus on screw osteointegration properties. Osteointegration was reportedly enhanced through various optimization strategies, including use of novel materials, surface modification techniques (e.g., application of coatings and topological optimization), and utilization of composites that allow synergistic effects between constituents. In this context, this paper takes a comprehensive path, starting with a brief presentation of spinal fixation devices, moving further to observations on how the pull-out strength can be enhanced with existing methods, and further focusing on techniques for implant osteointegration improvement.
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Affiliation(s)
- Bogdan Costăchescu
- “Gr. T. Popa” University of Medicine and Pharmacy, 700115 Iasi, Romania;
- “Prof. Dr. N. Oblu” Emergency Clinical Hospital, 700309 Iasi, Romania
| | - Adelina-Gabriela Niculescu
- Research Institute of the University of Bucharest—ICUB, University of Bucharest, 050657 Bucharest, Romania;
- Department of Science and Engineering of Oxide Materials and Nanomaterials, Politehnica University of Bucharest, 011061 Bucharest, Romania
| | - Alexandru Mihai Grumezescu
- Research Institute of the University of Bucharest—ICUB, University of Bucharest, 050657 Bucharest, Romania;
- Department of Science and Engineering of Oxide Materials and Nanomaterials, Politehnica University of Bucharest, 011061 Bucharest, Romania
- Academy of Romanian Scientists, Ilfov No. 3, 050044 Bucharest, Romania
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Mandelka E, Gierse J, Zimmermann F, Gruetzner PA, Franke J, Vetter SY. Implications of navigation in thoracolumbar pedicle screw placement on screw accuracy and screw diameter/pedicle width ratio. BRAIN & SPINE 2023; 3:101780. [PMID: 38020982 PMCID: PMC10668071 DOI: 10.1016/j.bas.2023.101780] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 05/22/2023] [Accepted: 07/10/2023] [Indexed: 12/01/2023]
Abstract
Introduction There is ample evidence that higher accuracy can be achieved in thoracolumbar pedicle screw placement by using spinal navigation. Still, to date, the evidence regarding the influence of the use of navigation on the screw diameter to pedicle width ratio remains limited. Research question The aim of this study was to investigate the implications of navigation in thoracolumbar pedicle screw placement not only on screw accuracy, but on the screw diameter to pedicle width ratio as well. Material and methods In this single-center single-surgeon study, 45 Patients undergoing navigated thoracolumbar pedicle screw placement were prospectively included. The results were compared with a matched comparison group of patients in which screw placement was performed under fluoroscopic guidance. The screw accuracy and the screw diameter to pedicle width ratio of every screw were compared between the groups. Results Screw accuracy was significantly higher in the navigation group compared to the fluoroscopic guidance group, alongside with a significant increase of the screw diameter to pedicle width ratio by approximately 10%. In addition, both the intraoperative radiation dose and the operating time tended to be lower in the study group. Conclusion This study was able to show that navigated thoracolumbar pedicle screw placement not only increases the accuracy of screw placement but also facilitates the selection of the adequate screw sizes, which according to the literature has positive effects on fixation strength. Meanwhile, the use of navigation did not negatively affect the time needed for surgery or the patient's intraoperative exposure to radiation.
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Affiliation(s)
- Eric Mandelka
- Research group Medical Imaging and Navigation in Trauma and Orthopedic Surgery (MINTOS), Department of Orthopedics and Trauma Surgery, BG Klinik Ludwigshafen, Ludwig-Guttmann-Str. 13, 67071, Ludwigshafen, Germany
| | - Jula Gierse
- Research group Medical Imaging and Navigation in Trauma and Orthopedic Surgery (MINTOS), Department of Orthopedics and Trauma Surgery, BG Klinik Ludwigshafen, Ludwig-Guttmann-Str. 13, 67071, Ludwigshafen, Germany
| | - Felix Zimmermann
- Research group Medical Imaging and Navigation in Trauma and Orthopedic Surgery (MINTOS), Department of Orthopedics and Trauma Surgery, BG Klinik Ludwigshafen, Ludwig-Guttmann-Str. 13, 67071, Ludwigshafen, Germany
| | - Paul A. Gruetzner
- Research group Medical Imaging and Navigation in Trauma and Orthopedic Surgery (MINTOS), Department of Orthopedics and Trauma Surgery, BG Klinik Ludwigshafen, Ludwig-Guttmann-Str. 13, 67071, Ludwigshafen, Germany
| | - Jochen Franke
- Research group Medical Imaging and Navigation in Trauma and Orthopedic Surgery (MINTOS), Department of Orthopedics and Trauma Surgery, BG Klinik Ludwigshafen, Ludwig-Guttmann-Str. 13, 67071, Ludwigshafen, Germany
| | - Sven Y. Vetter
- Research group Medical Imaging and Navigation in Trauma and Orthopedic Surgery (MINTOS), Department of Orthopedics and Trauma Surgery, BG Klinik Ludwigshafen, Ludwig-Guttmann-Str. 13, 67071, Ludwigshafen, Germany
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25
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Song F, Liu Y, Fu R, Gao X, Iqbal K, Yang D, Liu Y, Yang H. Craniocaudal toggling increases the risk of screw loosening in osteoporotic vertebrae. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2023; 238:107625. [PMID: 37263117 DOI: 10.1016/j.cmpb.2023.107625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 05/24/2023] [Accepted: 05/25/2023] [Indexed: 06/03/2023]
Abstract
BACKGROUND AND OBJECTIVE Screw loosening remains a prominent problem for osteoporotic patients undergoing pedicle screw fixation surgeries but its underlying mechanisms are not fully understood. This study sought to examine the interactive effect of craniocaudal or axial cyclic loading (toggling) and osteoporosis on screw fixation. METHODS QCT-based finite element models of normal (n = 7; vBMD = 156 ± 13 mg/cm3) and osteoporotic vertebrae (n = 7; vBMD = 72 ± 6 mg/cm3) were inserted with pedicle screws and loaded with or without craniocaudal toggling. Among them, a representative normal vertebra (age: 55; BMD: 140 mg/cm3) and an osteoporotic vertebra (age: 64; BMD: 79 mg/cm3) were also loaded with or without axial toggling. The individual and interactive effects of craniocaudal toggling and osteoporosis on screw fixation strength (the force when the pull-up displacement of the screw head reached 1 mm) and bone tissue failure (characterized by equivalent plastic strain) were examined by repeated measure ANOVA. RESULTS A significant interactive effect between craniocaudal toggling and osteoporosis on screw fixation strength was detected (p = 0.008). Specifically, craniocaudal toggling led to a marked decrease in the fixation strength (68%, p < 0.05) and stiffness (83%, p < 0.05) only in the osteoporotic vertebrae but had no effect on screw fixation strength and stiffness of the normal vertebrae (p > 0.05). Likewise, most of the bone tissues around the screw in the osteoporotic vertebrae yielded following craniocaudal toggling whereas this result was not seen in the normal vertebrae. The axial toggling had no significant effect on bone tissue failure as well as pedicle screw fixation in normal or osteoporotic vertebrae. CONCLUSIONS Craniocaudal toggling substantially reduces the screw fixation strength of the osteoporotic vertebrae by progressively increasing tissue failure around the screw, and therefore may contribute to the higher rates of screw loosening in osteoporotic compared to normal patients, whereas axial toggling is not a risk factor for pedicle screw loosening in normal or osteoporotic patients.
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Affiliation(s)
- Fei Song
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Yang Liu
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Ruisen Fu
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Xing Gao
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Kamran Iqbal
- Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education, Beijing University of Technology, Beijing, China
| | - Dongyue Yang
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Yuxuan Liu
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Haisheng Yang
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, China.
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Li C, Song L, Xiao J, Wu W, Jiang Y, Zhou R, Dai F. Second-generation bone cement-injectable cannulated pedicle screws for osteoporosis: biomechanical and finite element analyses. J Orthop Surg Res 2023; 18:343. [PMID: 37161530 PMCID: PMC10170841 DOI: 10.1186/s13018-023-03752-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 03/24/2023] [Indexed: 05/11/2023] Open
Abstract
BACKGROUND Biomechanical and finite element analyses were performed to investigate the efficacy of second-generation bone cement-injectable cannulated pedicle screws (CICPS) in osteoporosis. METHODS This study used the biomechanical test module of polyurethane to simulate osteoporotic cancellous bone. Polymethylmethacrylate (PMMA) bone cement was used to anchor the pedicle screws in the module. The specimens were divided into two groups for the mechanical tests: the experimental group (second-generation CICPS) and control group (first-generation CICPS). Safety was evaluated using maximum shear force, static bending, and dynamic bending tests. Biomechanical stability evaluations included the maximum axial pullout force and rotary torque tests. X-ray imaging and computed tomography were used to evaluate the distribution of bone cement 24 h after PMMA injection, and stress distribution at the screw fracture and screw-cement-bone interface was assessed using finite element analysis. RESULTS Mechanical testing revealed that the experimental group (349.8 ± 28.6 N) had a higher maximum axial pullout force than the control group (277.3 ± 8.6 N; P < 0.05). The bending moments of the experimental group (128.5 ± 9.08 N) were comparable to those of the control group (113.4 ± 20.9 N; P > 0.05). The screw-in and spin-out torques of the experimental group were higher than those of the control group (spin-in, 0.793 ± 0.015 vs. 0.577 ± 0.062 N, P < 0.01; spin-out, 0.764 ± 0.027 vs. 0.612 ± 0.049 N, P < 0.01). Bone cement was mainly distributed at the front three-fifths of the screw in both groups, but the distribution was more uniform in the experimental group than in the control group. After pullout, the bone cement was closely connected to the screw, without loosening or fragmentation. In the finite element analysis, stress on the second-generation CICPS was concentrated at the proximal screw outlet, whereas stress on the first-generation CICPS was concentrated at the screw neck, and the screw-bone cement-bone interface stress of the experimental group was smaller than that of the control group. CONCLUSION These findings suggest that second-generation CICPS have higher safety and stability than first-generation CICPS and may be a superior choice for the treatment of osteoporosis.
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Affiliation(s)
- Congcan Li
- Department of Orthopaedics, First Affiliated Hospital, Army Medical University, No. 30 Gaotanyanzheng Street, Chongqing, 400038, China
| | - Lei Song
- Department of Orthopaedics, First Affiliated Hospital, Army Medical University, No. 30 Gaotanyanzheng Street, Chongqing, 400038, China
| | - Jun Xiao
- Department of Special Service Physiological Training, Guangzhou Special Service Recuperation Center of PLA Rocket Force, Shantou, 515515, China
| | - Wenwen Wu
- Chinese People's Liberation Army 132U, Tunchang, 571627, China
| | - Yifan Jiang
- Fourth Department of Convalescence, Sanya Rehabilitation and Convalescent Center, Joint Logistics Support Force, Sanya, 572000, China
| | - Rui Zhou
- Department of Orthopaedics, First Affiliated Hospital, Army Medical University, No. 30 Gaotanyanzheng Street, Chongqing, 400038, China.
| | - Fei Dai
- Department of Orthopaedics, First Affiliated Hospital, Army Medical University, No. 30 Gaotanyanzheng Street, Chongqing, 400038, China.
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Schömig F, Becker L, Schönnagel L, Völker A, Disch AC, Schnake KJ, Pumberger M. Avoiding Spinal Implant Failures in Osteoporotic Patients: A Narrative Review. Global Spine J 2023; 13:52S-58S. [PMID: 37084355 PMCID: PMC10177307 DOI: 10.1177/21925682231159066] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/23/2023] Open
Abstract
STUDY DESIGN Narrative review. OBJECTIVES With an aging population, the prevalence of osteoporosis is continuously rising. As osseous integrity is crucial for bony fusion and implant stability, previous studies have shown osteoporosis to be associated with an increased risk for implant failure and higher reoperation rates after spine surgery. Thus, our review's purpose was to provide an update of evidence-based solutions in the surgical treatment of osteoporosis patients. METHODS We summarize the existing literature regarding changes associated with decreased bone mineral density (BMD) and resulting biomechanical implications for the spine as well as multidisciplinary treatment strategies to avoid implant failures in osteoporotic patients. RESULTS Osteoporosis is caused by an uncoupling of the bone remodeling cycle based on an unbalancing of bone resorption and formation and resulting reduced BMD. The reduction in trabecular structure, increased porosity of cancellous bone and decreased cross-linking between trabeculae cause a higher risk of complications after spinal implant-based surgeries. Thus, patients with osteoporosis require special planning considerations, including adequate preoperative evaluation and optimization. Surgical strategies aim towards maximizing screw pull-out strength, toggle resistance, as well as primary and secondary construct stability. CONCLUSIONS As osteoporosis plays a crucial role in the fate of patients undergoing spine surgery, surgeons need to be aware of the specific implications of low BMD. While there still is no consensus on the best course of treatment, multidisciplinary preoperative assessment and adherence to specific surgical principles help reduce the rate of implant-related complications.
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Affiliation(s)
- Friederike Schömig
- Center for Musculoskeletal Surgery, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Luis Becker
- Center for Musculoskeletal Surgery, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Lukas Schönnagel
- Center for Musculoskeletal Surgery, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Anna Völker
- Department of Orthopaedic, Trauma and Plastic Surgery, University Hospital Leipzig, Leipzig, Germany
| | - Alexander C Disch
- University Comprehensive Spine Center, University Center for Orthopedics, Traumatology and Plastic Surgery, Universitätsklinikum Carl Gustav Carus, Dresden, Germany
| | - Klaus John Schnake
- Center for Spinal and Scoliosis Surgery, Malteser Waldkrankenhaus St Marien gGmbH, Erlangen, Germany
- Department of Orthopedics and Traumatology, Paracelsus Private Medical University Nuremberg, Nuremberg, Germany
| | - Matthias Pumberger
- Center for Musculoskeletal Surgery, Charité - Universitätsmedizin Berlin, Berlin, Germany
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Computed Tomography-Based Prediction of Lumbar Pedicle Screw Loosening. BIOMED RESEARCH INTERNATIONAL 2023; 2023:8084597. [PMID: 36743516 PMCID: PMC9891825 DOI: 10.1155/2023/8084597] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Revised: 01/03/2023] [Accepted: 01/16/2023] [Indexed: 01/27/2023]
Abstract
Objective Pedicle screw loosening is one of the main complications after pedicle screw fixation. However, there are few reliable measures for prediction of screw loosening. The current study was carried out to find an effective method to use preoperative CT scanning as a predictor of screw loosening in the elderly patients and provide guidance for preoperative surgical planning. Methods Patients who were treated with lumbar pedicle screw fixation procedure in our department for degenerative lumbar disorders between January 2015 and January 2021 were retrospectively included in the current study. CT scan attenuation of each vertebra was measured with Hounsfield units (HU). Screw loosening was determined in postoperatively X-ray tests. One-way analysis of variance (ANOVA) and receiver operating characteristic (ROC) curve analysis were carried out with IBMSPSS 24.00 software. Results Screw loosening was observed in 44 of 215 patients (124 male, 91 female, average age 58.4 ± 7.6 years) during a mean follow-up time of 19.0 ± 11.2 months (range 12-32 months). No significant differences were found among the patients concerning patient gender, BMI, habit of smoking, and whether or not the patient had diabetes or suffered from spondylolisthesis (P > 0.05). The average HU value of lumbar vertebra was 122.4 ± 32.8 HU in the screw loosening group and 142.4 ± 38.2 HU in the control group, and the difference was significant (P < 0.01). ROC curve analysis revealed that the average HU value of L1-L5 has a relatively larger area under the curve (AUC) of 0.689 (95% CI: 0.605-0.773). With the sensitivity of 68% and specificity of 57%, a HU cut-off value of ≤124 HU is a plausible cut-off point to predict screw loosening. Conclusions A prospective CT scan HU value-based prediction can be used to decide whether or not to use screw augmentation methods. A cut-off L1-L5 average HU value of 124 HU can be used as an independent risk factor for screw loosening in instrumented lumbar vertebra. More predictive indexes should be involved to achieve higher sensitivity and specificity in future clinical practice.
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Patient-specific finite element modeling of scoliotic curve progression using region-specific stress-modulated vertebral growth. Spine Deform 2023; 11:525-534. [PMID: 36593421 PMCID: PMC10147794 DOI: 10.1007/s43390-022-00636-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 12/17/2022] [Indexed: 01/04/2023]
Abstract
PURPOSE This study describes the creation of patient-specific (PS) osteo-ligamentous finite element (FE) models of the spine, ribcage, and pelvis, simulation of up to three years of region-specific, stress-modulated growth, and validation of simulated curve progression with patient clinical angle measurements. RESEARCH QUESTION Does the inclusion of region-specific, stress-modulated vertebral growth, in addition to scaling based on age, weight, skeletal maturity, and spine flexibility allow for clinically accurate scoliotic curve progression prediction in patient-specific FE models of the spine, ribcage, and pelvis? METHODS Frontal, lateral, and lateral bending X-Rays of five AIS patients were obtained for approximately three-year timespans. PS-FE models were generated by morphing a normative template FE model with landmark points obtained from patient X-rays at the initial X-ray timepoint. Vertebral growth behavior and response to stress, as well as model material properties were made patient-specific based on several prognostic factors. Spine curvature angles from the PS-FE models were compared to the corresponding X-ray measurements. RESULTS Average FE model errors were 6.3 ± 4.6°, 12.2 ± 6.6°, 8.9 ± 7.7°, and 5.3 ± 3.4° for thoracic Cobb, lumbar Cobb, kyphosis, and lordosis angles, respectively. Average error in prediction of vertebral wedging at the apex and adjacent levels was 3.2 ± 2.2°. Vertebral column stress ranged from 0.11 MPa in tension to 0.79 MPa in compression. CONCLUSION Integration of region-specific stress-modulated growth, as well as adjustment of growth and material properties based on patient-specific data yielded clinically useful prediction accuracy while maintaining physiological stress magnitudes. This framework can be further developed for PS surgical simulation.
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Widmer J, Aubin CE, van Lenthe GH, Matsukawa K. Editorial: Innovations to improve screw fixation in traumatology and orthopedic surgery. Front Bioeng Biotechnol 2022; 10:1094813. [PMID: 36507265 PMCID: PMC9733944 DOI: 10.3389/fbioe.2022.1094813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 11/16/2022] [Indexed: 11/27/2022] Open
Affiliation(s)
- Jonas Widmer
- Department of Orthopedics, Balgrist University Hospital, Zürich, Switzerland,*Correspondence: Jonas Widmer,
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Harris G, Patel N, Quintero D, Jenkins N, Kaplan L, Rey J, Jose J. Brachial artery thrombosis secondary to fixation screw pullout: Case report. Radiol Case Rep 2022; 17:3959-3962. [PMID: 35991383 PMCID: PMC9388874 DOI: 10.1016/j.radcr.2022.06.071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 06/17/2022] [Accepted: 06/21/2022] [Indexed: 11/21/2022] Open
Abstract
The vascular supply of the shoulder and forearm are principal derivates of the ipsilateral subclavian artery. The trajectory of this arterial supply predisposes it to concomitant injuries in the shoulder and clavicular fractures proximally and elbow dislocation distally. Distal bicep tendon tears often occur most commonly in middle-aged men due to trauma to the elbow, typically in weight-bearing situations [1]. To our knowledge, this is the first case of distal biceps tendon tear repair resulting in distal brachial artery injury from displaced hardware due to postoperative re-injury. We present a case of a 41-year-old male who developed a vaso-occluding hematoma at the distal biceps secondary to a displaced fixation screw. The patient required emergency vascular surgery with embolectomy and arterial bypass. Although this patient fully recovered, the clinical course the patient experienced could have been minimized with appropriate postoperative care. This report aims to alert clinicians to the relevant local anatomy and relate it to the proposed mechanism of injury, thereby bringing attention to the importance of postoperative limb protection in at-risk patients. The timing of the injury, and the protracted rate of thrombus formation suggest that the brachial artery's thrombosis was associated with the screw pullout during reinjury of the area. Screw pullout in orthopedics is a rare phenomenon that can lead to significant complications. The risk of reinjury, screw pullout, and other complications such as thrombosis is evidence to support the careful treatment of the area postoperatively.
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Affiliation(s)
- Griffin Harris
- University of Miami Leonard Miller School of Medicine, Miami, FL, USA
| | - Nikhil Patel
- University of Miami Leonard Miller School of Medicine, Miami, FL, USA
| | - Daniel Quintero
- University of Miami Leonard Miller School of Medicine, Miami, FL, USA
| | - Nathaniel Jenkins
- Department of Orthopaedics, Miller School of Medicine, University of Miami, Miami, Florida
| | - Lee Kaplan
- UHealth Sports Medicine Institute, University of Miami Miller School of Medicine, FL
| | - Jorge Rey
- University of Miami Miller School of Medicine, Department of Surgery, Division of Vascular and Endovascular Surgery
| | - Jean Jose
- University of Miami, Leonard Miller School of Medicine, Department of Radiology, Miami, FL, USA
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NIE JIACHEN, DING LI, ZHANG QING, LIU SHENGHUI, SHI HUIJUAN, ZHANG ZHONGCAI, ZOU HAIBO. THE FIXATION EFFECT OF DIFFERENT TYPES OF SCREWS IN THE WHOLE OSTEOPOROTIC LUMBAR VERTEBRAE: AN FEA STUDY. J MECH MED BIOL 2022. [DOI: 10.1142/s0219519422500348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Purpose: The aim of this study is to explore how pedicle screws (PSs) and cortical bone trajectory (CBT) screws differ in fixation strength when implanted in L1–L5 with osteoporosis, providing support for choosing implants and trajectories in spine internal fixation surgeries. Methods: We filtered 30 lumbar segments out from CT images of eight osteoporotic participants and simulated PS or CBT screw implantation in each segment, generating 60 vertebra-screw assembly FE models. To evaluate the fixation effect, we performed a pull-out force test simulation in each model and analyzed the maximal pull-out force, pull-out stiffness, and equivalent stress of vertebrae and screws. Results: The maximal pull-out force of PS and CBT screws in L1–L5 was in the range of 905–1552 (N) and 587–1012 (N), while the pull-out stiffness was in the range of 1990–2617 (N/mm) and 1007–1681 (N/mm). The fixation strength of PS in L4 and L5 was higher ([Formula: see text]), while in L1–L3 PS and CBT screws are similar ([Formula: see text]). The maximal stress of vertebrae and screws when PS was pulled at 0.25[Formula: see text]mm was larger than that of CBT screws. Conclusions: For patients with moderate osteoporosis, it is recommended to insert PS into L4 and L5 to attain better fixation strength, but vertebrae are more prone to fracture. Consequently, under severe osteoporosis, the implantation of CBT screws should be considered first. Bone cement injection may be necessary to consolidate the screw-vertebrae interface with osteoporosis.
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Affiliation(s)
- JIACHEN NIE
- Key Laboratory of Biomechanics and Mechanobiology (Beihang University), Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, P. R. China
- Spine Division of Orthopaedic Department, China-Japan Friendship Hospital, Beijing 100029 P. R. China
| | - LI DING
- Key Laboratory of Biomechanics and Mechanobiology (Beihang University), Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, P. R. China
- Spine Division of Orthopaedic Department, China-Japan Friendship Hospital, Beijing 100029 P. R. China
| | - QING ZHANG
- Key Laboratory of Biomechanics and Mechanobiology (Beihang University), Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, P. R. China
- Spine Division of Orthopaedic Department, China-Japan Friendship Hospital, Beijing 100029 P. R. China
| | - SHENGHUI LIU
- Key Laboratory of Biomechanics and Mechanobiology (Beihang University), Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, P. R. China
- Spine Division of Orthopaedic Department, China-Japan Friendship Hospital, Beijing 100029 P. R. China
| | - HUIJUAN SHI
- Key Laboratory of Biomechanics and Mechanobiology (Beihang University), Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, P. R. China
- Spine Division of Orthopaedic Department, China-Japan Friendship Hospital, Beijing 100029 P. R. China
| | - ZHONGCAI ZHANG
- Spine Division of Orthopaedic Department, China-Japan Friendship Hospital, Beijing 100029 P. R. China
| | - HAIBO ZOU
- Spine Division of Orthopaedic Department, China-Japan Friendship Hospital, Beijing 100029 P. R. China
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Song F, Feng W, Yang D, Li G, Iqbal K, Liu Y, Yang H. A Novel Screw Modeling Approach to Study the Effects of Screw Parameters on Pullout Strength. J Biomech Eng 2022; 145:1143328. [PMID: 35864784 DOI: 10.1115/1.4055035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Indexed: 11/08/2022]
Abstract
Screw loosening remains a prominent problem for osteoporotic patients undergoing pedicle screw fixation surgeries and is affected by screw parameters (e.g., diameter, pitch and thread angle). However, the individual and interactive effects of these parameters on screw fixation are not fully understood. Furthermore, current finite element modeling of an threaded screw is less computationally efficient. To address these issues, we (1) explored a novel "simulated threaded screw" approach (virtual threads assigned to the contact elements of a simplified screw) and compared its performance with threaded and simplified screws, and (2) examined with this approach the individual and interactive effects of altering screw diameter (5.5-6.5 mm), pitch (1-2 mm) and half-thread angle (20-30°) on pullout strength of normal vertebrae. Results demonstrated that the "simulated threaded screw" approach equivalently predicted pullout strength compared to the "threaded screw" approach (R2 = 0.99, slope = 1). We further found that the pullout strength was most sensitive to the change in screw diameter, followed by thread angle, pitch and interactions of diameter*pitch or diameter*angle. In conclusion, the "simulated threaded screw" approach can achieve the same predictive capability compared to threaded modeling of the screw. The current findings may serve as useful references for planning of screw parameters, so as to improve the complication of screw loosening.
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Affiliation(s)
- Fei Song
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing, 100124, China
| | - Wentian Feng
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing, 100124, China
| | - Dongyue Yang
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing, 100124, China
| | - Guanghui Li
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing, 100124, China
| | - Kamran Iqbal
- Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing, 100124, China
| | - Yuxuan Liu
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing, 100124, China
| | - Haisheng Yang
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing, 100124, China
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Abstract
STUDY DESIGN Multicenter retrospective review. OBJECTIVE To calculate overall incidence of pedicle screw "plowing" in adolescent idiopathic scoliosis (AIS) patients who underwent posterior spinal fusion (PSF). To identify risk factors for pedicle screw plowing and associated postoperative outcomes, including loss of correction and revision rate. SUMMARY OF BACKGROUND DATA Curve correction of AIS generates perpendicular stresses that can cause pedicle screws to lose alignment and "plow" through pedicles craniocaudally. METHODS We reviewed records of 1057 patients who underwent PSF for AIS from 2002 to 2015. Preoperative and first postoperative erect radiographs were evaluated by two observers to determine (1) presence of plowing and (2) subsequent loss of correction (LOC). Plowing was defined as more than 25° sagittal angulation compared with pedicle axis or entry of the most dorsal part of the screw outside the pedicle projection. LOC was defined as postoperative change in focal angulation of an instrumented spinal level, when in consensus of both reviewers. Bivariate analyses were performed (alpha = 0.05). RESULTS Nineteen thousand five hundred sixty nine screws were assessed across our cohort of 1057 patients. Both observers agreed that 48 patients (4.5%) demonstrated plowing of more than or equal to one pedicle screw. For 72 screws (0.4%), both observers noted plowing, most commonly through the cranial cortex of the pedicle (65/72 screws) and at the lowest instrument vertebra (LIV) (17/72 screws). Factors associated with plowing included larger curves (P = 0.02); lower mean pedicle screw density (P = 0.0003); skeletal immaturity as measured by open triradiate cartilage (P = 0.04); and younger chronological age at time of surgery (P = 0.04). LOC occurred in 13 patients, most commonly at LIV (P < 0.0001). Revision rate for loss of screw fixation was higher in the plowing group (P = 0.003). CONCLUSION Pedicle screw plowing occurred in 4.5% of AIS patients, especially in those skeletally immature and with decreased implant density. Plowing commonly occurred in the cranial direction and was associated with LOC, particularly at the LIV.Level of Evidence: 3.
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Weidling M, Heilemann M, Schoenfelder S, Heyde CE. Influence of thread design on anchorage of pedicle screws in cancellous bone: an experimental and analytical analysis. Sci Rep 2022; 12:8051. [PMID: 35577852 PMCID: PMC9110386 DOI: 10.1038/s41598-022-11824-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 04/28/2022] [Indexed: 11/12/2022] Open
Abstract
Threads of modern pedicle screws can vary greatly in design. It is difficult to assess which interplay of design features is particularly advantageous for screw anchorage. This study aims to increase the understanding of the anchorage behaviour between screw and cancellous bone. Pull-out tests of six pedicle screws in two sizes each were performed on three densities of biomechanical test material. More general screw characteristics were derived from the screw design and evaluated using the test data. Selected screws were tested on body donor material. Some screw characteristics, such as compacting, are well suited to compare the different thread designs of screws with tapered core. The combination of two characteristics, one representing bone compacting and one representing thread flank area, appears to be particularly advantageous for assessing anchorage behaviour. With an equation derived from these characteristics, the pull-out strength could be calculated very accurately (mean deviation 1%). Furthermore, findings are corroborated by tests on donor material. For screws with tapered core, the design demands for good anchorage against pull-out from cancellous bone change with material density. With sufficient bone quality, screws with a high compacting effect are advantageous, while with low bone density a high thread flank area also appears necessary for better screw anchorage.
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Affiliation(s)
- Martin Weidling
- Department of Orthopaedic Surgery, Traumatology and Plastic Surgery, ZESBO - Center for Research on Musculoskeletal Systems, Leipzig University, Leipzig, Germany.
| | - Martin Heilemann
- Department of Orthopaedic Surgery, Traumatology and Plastic Surgery, ZESBO - Center for Research on Musculoskeletal Systems, Leipzig University, Leipzig, Germany
| | - Stephan Schoenfelder
- Faculty of Engineering, University of Applied Sciences Leipzig, Leipzig, Germany
| | - Christoph E Heyde
- Department of Orthopaedic Surgery, Traumatology and Plastic Surgery, Leipzig University Medical Center, Leipzig, Germany
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Wang H, Du T, Li R, Main RP, Yang H. Interactive effects of various loading parameters on the fluid dynamics within the lacunar-canalicular system for a single osteocyte. Bone 2022; 158:116367. [PMID: 35181573 DOI: 10.1016/j.bone.2022.116367] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 02/11/2022] [Accepted: 02/11/2022] [Indexed: 12/26/2022]
Abstract
The osteocyte lacunar-canalicular system (LCS) serves as a mechanotransductive core where external loading applied to the skeleton is transduced into mechanical signals (e.g., fluid shear) that can be sensed by mechanosensors (osteocytes). The fluid velocity and shear stress within the LCS are affected by various loading parameters. However, the interactive effect of distinct loading parameters on the velocity and shear stress in the LCS remains unclear. To address this issue, we developed a multiscale modeling approach, combining a poroelastic finite element (FE) model with a single osteocytic LCS unit model to calculate the flow velocity and shear stress within the LCS. Next, a sensitivity analysis was performed to investigate individual and interactive effects of strain magnitude, strain rate, number of cycles, and intervening short rests between loading cycles on the velocity and shear stress around the osteocyte. Lastly, we developed a relatively simple regression model to predict those outcomes. Our results demonstrated that the strain magnitude or rate alone were the main factors affecting the velocity and shear stress; however, the combination of these two was not directly additive, and addition of a short rest between cycles could enhance the combination of these two related factors. These results show highly interactive effects of distinct loading parameters on fluid velocity and shear stress in the LCS. Specifically, our results suggest that an enhanced fluid dynamics environment in the LCS can be achieved with a brief number of load cycles combined with short rest insertion and high strain magnitude and rate.
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Affiliation(s)
- Huiru Wang
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China
| | - Tianming Du
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China
| | - Rui Li
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China
| | - Russell P Main
- Musculoskeletal Biology and Mechanics Lab, Department of Basic Medical Sciences, Purdue University, IN, USA; Weldon School of Biomedical Engineering, Purdue University, IN, USA
| | - Haisheng Yang
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China.
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Anterior Transarticular Crossing Screw Placement for Atlantoaxial Instability in Children: Computed Tomography-Based Study. World Neurosurg 2022; 161:e192-e198. [PMID: 35183796 DOI: 10.1016/j.wneu.2022.01.096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 01/23/2022] [Accepted: 01/23/2022] [Indexed: 11/20/2022]
Abstract
OBJECTIVE The feasibility of anterior transarticular crossing screw (ATCS) fixation for atlantoaxial instability was confirmed in adults. However, atlantoaxial instability is more common in children. Therefore this study was aimed to ascertain the pediatric morphometric characteristics of ATCS in C1-2. METHODS Morphometric analysis was conducted on computed tomography scan in 87 pediatric patients who were divided into groups based on ages (1-6 years, 7-10 years, and 11-16 years). Measurements were taken in sagittal and axial planes of computed tomography imaging to determine the range of screw lateral angles, incline angles, and screw lengths. RESULTS The overall screw lengths were relatively longer in males than females. For those aged 1-6 years, the screw lengths were 25.5-32.8 mm in males and 24.2-31.3 mm in females, respectively. The screw lengths showed no difference in the 7- to 10-year group between sexes, while the incline angle was larger in females than males. And the screw lengths were 33.5-43.2 mm in males and 31.2-40.4 mm in females in the 11- to 16-year group. The screw lengths were increased with age, yet the lateral angles were decreased. We also found that the epiphyseal closure of odontoid reached 93.6% when the age was older than 7 years old. Therefore ATCS was recommended for children older than 7 years. CONCLUSIONS The overall screw lengths and lateral angles of ATCS were larger in male children than those in females, but the incline angles were larger in females. ATCS is feasible in children, particularly those aged 7 years or older.
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Balasubramanian S, D'Andrea C, Viraraghavan G, Cahill PJ. Development of a Finite Element Model of the Pediatric Thoracic and Lumbar Spine, Ribcage, and Pelvis with Orthotropic Region-Specific Vertebral Growth. J Biomech Eng 2022; 144:1140398. [PMID: 35466381 DOI: 10.1115/1.4054410] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Indexed: 11/08/2022]
Abstract
Finite element (FE) modeling of the spine has increasingly been applied in orthopedic precision-medicine approaches. Previously published FE models of the pediatric spine growth have made simplifications in geometry of anatomical structures, material properties, and representation of vertebral growth. To address those limitations, a comprehensive FE model of a pediatric (10-year-old) osteo-ligamentous thoracic and lumbar spine (T1-L5 with intervertebral discs (IVDs) and ligaments), ribcage, and pelvis with age- and level-specific ligament properties and orthotropic region-specific vertebral growth was developed and validated. Range of motion (ROM) measures, namely lateral bending, flexion-extension, and axial rotation, of the current 10 YO FE model were generally within reported ranges of scaled in vitro adult ROM data. Changes in T1-L5 spine height, as well as kyphosis (T2-T12) and lordosis (L1-L5) angles in the current FE model for two years of growth (from ages 10 to 12 years) were within ranges reported from corresponding pediatric clinical data. The use of such comprehensive pediatric FE models can provide clinically relevant insights into normative and pathological biomechanical responses of the spine, and also contribute to the development and optimization of clinical interventions for spine deformities.
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Affiliation(s)
- Sriram Balasubramanian
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, USA
| | - Christian D'Andrea
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, USA
| | - Girish Viraraghavan
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, USA
| | - Patrick J Cahill
- Division of Orthopaedics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
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Maitirouzi J, Luo H, Zhou Z, Ren H, Rexiti P. Finite element analysis of human lumbar vertebrae in internal fixation system model with different bone density trajectories. Int J Artif Organs 2022; 45:478-487. [PMID: 35441547 DOI: 10.1177/03913988221088613] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
PURPOSE To evaluate the biomechanics effect of modified cortical bone screw technique (MCBT) with other traditional internal fixation systems on lumbar osteoporotic wet specimen. METHODS Four different finite element models were established using CT data: (1) lumbar osteoporosis model without internal fixation system; (2) traditional pedicle screw technology (TT) model; (3) traditional cortical bone screw technology (CBT) model; (4) MCBT model. The changes of global displacement, intervertebral disc displacement of all models and internal fixation system Von Mises stress among the three models were compared under the same physiological load. RESULTS Compared with the other three models, the total displacement of the modified CBT screw model was the smallest, with the maximum displacement of 0.216 mm; The intervertebral disc displacement of the modified CBT screw model was the smallest, with the maximum displacement of 0.149 mm; the internal fixation system Von Mises stress of the modified CBT screw technique model was the largest compared with the other three models, The maximum Von Mises stress is 232.73 MPa. CONCLUSION Compared to traditional pedicle screw and traditional CBT, MCBT has better mechanical stability, and it is of certain clinical application value.
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Affiliation(s)
- Julaiti Maitirouzi
- College of Mechanical Engineering, Xin jiang University, Urumqi, Xin jiang, China
| | - Huiqing Luo
- College of Mechanical Engineering, Xin jiang University, Urumqi, Xin jiang, China
| | - Zhihao Zhou
- Departments of Spine Surgery, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, China
| | - Hangning Ren
- College of Mechanical Engineering, Xin jiang University, Urumqi, Xin jiang, China
| | - Paerhati Rexiti
- Departments of Spine Surgery, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, China
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Dubé-Cyr R, Villemure I, Arnoux PJ, Rawlinson J, Aubin CÉ. Instrumentation of the sacroiliac joint with cylindrical threaded implants: A detailed finite element study of patient characteristics affecting fixation performance. J Orthop Res 2021; 39:2693-2702. [PMID: 33620100 DOI: 10.1002/jor.25012] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 01/27/2021] [Accepted: 02/21/2021] [Indexed: 02/04/2023]
Abstract
The sacroiliac joint (SIJ) is a known pain generator that, in severe cases, may require surgical fixation to reduce intra-articular displacements and allow for arthrodesis. The objective of this computational study was to analyze how the number of implants affected SIJ stabilization with patient-specific characteristics such as the pelvic geometry and bone quality. Detailed finite element models were developed to account for three pelvises of differing anatomy. Each model was tested with a normal and low bone density (LD) under two types of loading: compression only and compression with flexion and extension moments. These models were instrumented with one to three cylindrical, threaded and fenestrated implants through a posterior oblique trajectory, requiring less muscle dissection than the more common lateral trajectory used with triangular implants. Compared with the noninstrumented pelvis, the change in range of motion (ROM) and stress distribution were used to characterize joint stabilization. Noninstrumented mobility ranged from 0.86 to 2.55 mm and from 1.37° to 6.11°. Across patient-specific characteristics, the ROM reduction with one implant varied from 3% to 21% for vertical and 15% to 47% for angular displacements. With two implants, the ROM reduction ranged from 12% to 41% for vertical and from 28% to 61% for angular displacements. Three implants, however, did not further improve the joint stability (14% to 42% for vertical and 32% to 63% for angular displacements). With respect to patient characteristics, an LD led to a decreased stabilization and a higher volume of stressed bone (>75% of yield stress). A better understanding of how patient characteristics affect the implant performance could help improve surgical planning of sacroiliac arthrodesis.
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Affiliation(s)
- Roxanne Dubé-Cyr
- Department of Mechanical Engineering, Polytechnique Montréal, Montreal, Quebec, Canada.,Sainte-Justine University Hospital Center, Montreal, Quebec, Canada.,iLab-Spine (International Laboratory-Spine Imaging and Biomechanics), Marseille, France.,Laboratoire de Biomécanique Appliquée, IFSTTAR, LBA UMR T24, Boulevard Pierre Dramard, Aix-Marseille Université, Marseille, France
| | - Isabelle Villemure
- Department of Mechanical Engineering, Polytechnique Montréal, Montreal, Quebec, Canada.,Sainte-Justine University Hospital Center, Montreal, Quebec, Canada.,iLab-Spine (International Laboratory-Spine Imaging and Biomechanics), Marseille, France
| | - Pierre-Jean Arnoux
- iLab-Spine (International Laboratory-Spine Imaging and Biomechanics), Marseille, France.,Laboratoire de Biomécanique Appliquée, IFSTTAR, LBA UMR T24, Boulevard Pierre Dramard, Aix-Marseille Université, Marseille, France
| | - Jeremy Rawlinson
- Department of Mechanical Engineering, Polytechnique Montréal, Montreal, Quebec, Canada.,Medtronic, Spinal Applied Research, Memphis, Tennessee, USA
| | - Carl-Éric Aubin
- Department of Mechanical Engineering, Polytechnique Montréal, Montreal, Quebec, Canada.,Sainte-Justine University Hospital Center, Montreal, Quebec, Canada.,iLab-Spine (International Laboratory-Spine Imaging and Biomechanics), Marseille, France
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Siemionow KB, Forsthoefel CW, Foy MP, Gawel D, Luciano CJ. Autonomous lumbar spine pedicle screw planning using machine learning: A validation study. JOURNAL OF CRANIOVERTEBRAL JUNCTION AND SPINE 2021; 12:223-227. [PMID: 34728987 PMCID: PMC8501821 DOI: 10.4103/jcvjs.jcvjs_94_21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 07/28/2021] [Indexed: 11/06/2022] Open
Abstract
Introduction: Several techniques for pedicle screw placement have been described including freehand techniques, fluoroscopy assisted, computed tomography (CT) guidance, and robotics. Image-guided surgery offers the potential to combine the benefits of CT guidance without the added radiation. This study investigated the ability of a neural network to place lumbar pedicle screws with the correct length, diameter, and angulation autonomously within radiographs without the need for human involvement. Materials and Methods: The neural network was trained using a machine learning process. The method combines the previously reported autonomous spine segmentation solution with a landmark localization solution. The pedicle screw placement was evaluated using the Zdichavsky, Ravi, and Gertzbein grading systems. Results: In total, the program placed 208 pedicle screws between the L1 and S1 spinal levels. Of the 208 placed pedicle screws, 208 (100%) had a Zdichavsky Score 1A, 206 (99.0%) of all screws were Ravi Grade 1, and Gertzbein Grade A indicating no breech. The final two screws (1.0%) had a Ravi score of 2 (<2 mm breech) and a Gertzbein grade of B (<2 mm breech). Conclusion: The results of this experiment can be combined with an image-guided platform to provide an efficient and highly effective method of placing pedicle screws during spinal stabilization surgery.
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Affiliation(s)
| | | | - Michael P Foy
- Department of Orthopaedics, University of Illinois, Chicago, IL, USA
| | - Dominik Gawel
- Department of Research, Holo Surgical Inc, Chicago, IL, USA
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Çetin A, Bircan DA. 3D pull-out finite element simulation of the pedicle screw-trabecular bone interface at strain rates. Proc Inst Mech Eng H 2021; 236:134-144. [PMID: 34479459 DOI: 10.1177/09544119211044560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Biomedical experimental studies such as pull-out (PO), screw loosening experience variability mechanical properties of fresh bone, legal procedures of cadaver bone samples and time-consuming problems. Finite Element Method (FEM) could overcome experimental problems in biomechanics. However, material modelling of bone is quite difficult, which has viscoelastic and viscoplastic properties. The study presents a bone material model which is constructed at the strain rates with the Johnson-Cook (JC) material model, one of the robust constitutive material models. The JC material constants of trabecular bone are determined by the curve fitting method at strain rates for the 3D PO finite element simulation, which defines the screw-bone interface relationship. The PO simulation is performed using the Abaqus/CAE software program. Bone fracture mechanisms are simulated with dynamic/explicit solutions during the PO phenomenon. The paper exposes whether the strain rate has effects on the PO performance. Moreover, simulation reveals the relationship between pedicle screw diameter and PO performance. The results obtained that the maximum pull-out force (POF) improves as both the screw diameter and the strain rate increase. For 5.5 mm diameter pedicle screw POFs were 487, 517 and 1708 N at strain rate 0.00015, 0.015 and 0.015 s-1, respectively. The FOFs obtained from the simulation of the other screw were 730, 802 and 2008 N at strain rates 0.00015, 0.0015 and 0.015, respectively. PO phenomenon was also simulated realistically in the finite element analysis (FEA).
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Affiliation(s)
- Ahmet Çetin
- Department of Mechanical Engineering, Cukurova University, Adana, Turkey
| | - Durmuş Ali Bircan
- Department of Mechanical Engineering, Cukurova University, Adana, Turkey
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Barile F, Ruffilli A, Manzetti M, Fiore M, Panciera A, Viroli G, Faldini C. Resumption of sport after spinal fusion for adolescent idiopathic scoliosis: a review of the current literature. Spine Deform 2021; 9:1247-1251. [PMID: 33759111 PMCID: PMC8363544 DOI: 10.1007/s43390-021-00330-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 03/14/2021] [Indexed: 12/25/2022]
Abstract
BACKGROUND Adolescent idiopathic scoliosis (AIS) is a frequent disorder. Since patients with AIS are typically as active as age-matched controls and post-operative reduction in physical activity has detrimental effects on their well-being, return to sport (RTS) is an important perioperative concern. Aim of the present study is to review the literature concerning return to sport after spinal fusion for AIS. METHODS This work was carried out in accordance with Preferential Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. The search was carried out in December 2020. Only peer-reviewed randomized controlled trials (RCTs), retrospective studies (RS), retrospective case series (RCS) and perspective cohort studies (PCS) were considered for inclusion. RESULTS Six studies were included; only one of them was prospective. All the authors reported a time to RTS ranging between 6 and 18 months. Between 28 and 36.6% of all patients changed sport, choosing lower impact activities, mostly due to loss of flexibility of the spine. No complications due to return to play were noted. CONCLUSION According to current evidence, patients who received spinal arthrodesis for AIS can safely return to any sport, even those that require extreme levels of spinal and pelvic movements such as gymnastics and golf. As there is little evidence, however, of the spinal loading that occurs during such movements, there is a lack of scientific evidence-based recommendations or guidelines surgeons and other health care providers can follow. Prospective comparative studies are needed to investigate these biomechanical and clinical issues. LEVEL OF EVIDENCE Level III.
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Affiliation(s)
- Francesca Barile
- Department of Biomedical and Neuromotor Science - DIBINEM, 1st Orthopaedic and Traumatologic Clinic, IRCCS Istituto Ortopedico Rizzoli, University of Bologna, Via Giulio Cesare Pupilli 1, 40136, Bologna, Italy.
| | - Alberto Ruffilli
- Department of Biomedical and Neuromotor Science - DIBINEM, 1st Orthopaedic and Traumatologic Clinic, IRCCS Istituto Ortopedico Rizzoli, University of Bologna, Via Giulio Cesare Pupilli 1, 40136, Bologna, Italy
| | - Marco Manzetti
- Department of Biomedical and Neuromotor Science - DIBINEM, 1st Orthopaedic and Traumatologic Clinic, IRCCS Istituto Ortopedico Rizzoli, University of Bologna, Via Giulio Cesare Pupilli 1, 40136, Bologna, Italy
| | - Michele Fiore
- Department of Biomedical and Neuromotor Science - DIBINEM, 1st Orthopaedic and Traumatologic Clinic, IRCCS Istituto Ortopedico Rizzoli, University of Bologna, Via Giulio Cesare Pupilli 1, 40136, Bologna, Italy
| | - Alessandro Panciera
- Department of Biomedical and Neuromotor Science - DIBINEM, 1st Orthopaedic and Traumatologic Clinic, IRCCS Istituto Ortopedico Rizzoli, University of Bologna, Via Giulio Cesare Pupilli 1, 40136, Bologna, Italy
| | - Giovanni Viroli
- Department of Biomedical and Neuromotor Science - DIBINEM, 1st Orthopaedic and Traumatologic Clinic, IRCCS Istituto Ortopedico Rizzoli, University of Bologna, Via Giulio Cesare Pupilli 1, 40136, Bologna, Italy
| | - Cesare Faldini
- Department of Biomedical and Neuromotor Science - DIBINEM, 1st Orthopaedic and Traumatologic Clinic, IRCCS Istituto Ortopedico Rizzoli, University of Bologna, Via Giulio Cesare Pupilli 1, 40136, Bologna, Italy
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Caprara S, Fasser MR, Spirig JM, Widmer J, Snedeker JG, Farshad M, Senteler M. Bone density optimized pedicle screw instrumentation improves screw pull-out force in lumbar vertebrae. Comput Methods Biomech Biomed Engin 2021; 25:464-474. [PMID: 34369827 DOI: 10.1080/10255842.2021.1959558] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Pedicle screw instrumentation is performed in the surgical treatment of a wide variety of spinal pathologies. A common postoperative complication associated with this procedure is screw loosening. It has been shown that patient-specific screw fixation can be automated to match standard clinical practice and that failure can be estimated preoperatively using computed tomography images. Hence, we set out to optimize three-dimensional preoperative planning to achieve more mechanically robust screw purchase allowing deviation from intuitive, standard screw parameters. Toward this purpose, we employed a genetic algorithm optimization to find optimal screw sizes and trajectories by maximizing the CT derived bone mechanical properties. The method was tested on cadaveric lumbar vertebrae (L1 to L5) of four human spines (2 female/2 male; age range 60-78 years). The main boundary conditions were the predefined, level-dependent areas of possible screw entry points, as well as the automatically located pedicle structures. Finite element analysis was used to compare the genetic algorithm output to standard clinical planning of screw positioning in terms of the simulated pull-out strength. The genetic algorithm optimization successfully found screw sizes and trajectories that maximize the sum of the Young's modulus within the screw's volume for all 40 pedicle screws included in this study. Overall, there was a 26% increase in simulated pull-out strength for optimized compared to traditional screw trajectories and sizes. Our results indicate that optimizing pedicle screw instrumentation in lumbar vertebrae based on bone quality measures improves screw purchase as compared to traditional instrumentation.
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Affiliation(s)
- Sebastiano Caprara
- Department of Orthopaedics, Balgrist University Hospital, Zurich, Switzerland.,Institute of Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Marie-Rosa Fasser
- Department of Orthopaedics, Balgrist University Hospital, Zurich, Switzerland.,Institute of Biomechanics, ETH Zurich, Zurich, Switzerland
| | - José Miguel Spirig
- Department of Orthopaedics, Balgrist University Hospital, Zurich, Switzerland
| | - Jonas Widmer
- Department of Orthopaedics, Balgrist University Hospital, Zurich, Switzerland.,Institute of Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Jess G Snedeker
- Department of Orthopaedics, Balgrist University Hospital, Zurich, Switzerland.,Institute of Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Mazda Farshad
- Department of Orthopaedics, Balgrist University Hospital, Zurich, Switzerland
| | - Marco Senteler
- Department of Orthopaedics, Balgrist University Hospital, Zurich, Switzerland.,Institute of Biomechanics, ETH Zurich, Zurich, Switzerland
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Harris AB, Kebaish FN, Puvanesarajah V, Raad M, Wilkening MW, Jain A, Cohen DB, Neuman BJ, Kebaish KM. Caudally directed upper-instrumented vertebra pedicle screws associated with minimized risk of proximal junctional failure in patients with long posterior spinal fusion for adult spinal deformity. Spine J 2021; 21:1072-1079. [PMID: 33722729 DOI: 10.1016/j.spinee.2021.03.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 02/06/2021] [Accepted: 03/08/2021] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT It is unknown whether upper instrumented vertebra (UIV) pedicle screw trajectory and UIV screw-rod angle are associated with development of proximal junctional kyphosis (PJK) and/or proximal junctional failure (PJF). PURPOSE To determine whether (1) the cranial-caudal trajectory of UIV pedicle screws and (2) UIV screw-vertebra angle are associated with PJK and/or PJF after long posterior spinal fusion in patients with adult spinal deformity (ASD). STUDY DESIGN/SETTING Retrospective review. PATIENT SAMPLE We included 96 patients with ASD who underwent fusion from T9-T12 to the pelvis (>5 vertebrae fused) between 2008 and 2015. OUTCOME MEASURES Pedicle screw trajectory was measured as the UIV pedicle screw-vertebra angle (UIV-PVA), which is the mean of the two angles between the UIV superior endplate and both UIV pedicle screws. (Positive values indicate screws angled cranially; negative values indicate screws angled caudally.) We measured UIV rod-vertebra angle (UIV-RVA) between the rod at the point of screw attachment and the UIV superior endplate. METHODS During ≥2-year follow-up, 38 patients developed PJK, and 28 developed PJF. Mean (± standard deviation) UIV-PVA was -0.9° ± 6.0°. Mean UIV-RVA was 87° ± 5.2°. We examined the development of PJK and PJF using a UIV-PVA/UIV-RVA cutoff of 3° identified by a receiver operating characteristic curve, while controlling for osteoporosis, age, sex, and preoperative thoracic kyphosis. RESULTS Patients with UIV-PVA ≥3° had significantly greater odds of developing PJK (odds ratio 2.7; 95% confidence interval: 1.0-7.1) and PJF (odds ratio 3.6; 95% confidence interval: 1.3-10) compared with patients with UIV-PVA <3°. UIV-RVA was not significantly associated with development of PJK or PJF. CONCLUSIONS In long thoracic fusion to the pelvis for ASD, UIV-PVA ≥3° was associated with 2.7-fold greater odds of PJK and 3.6-fold greater odds of PJF compared with UIV-PVA <3°. UIV-RVA was not associated with PJK or PJF. LEVEL OF EVIDENCE III.
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Affiliation(s)
- Andrew B Harris
- Department of Orthopedic Surgery, The Johns Hopkins University, 601 N. Caroline St, JHOC 5223, Baltimore, MD, USA
| | - Floreana N Kebaish
- Department of Orthopedic Surgery, The Johns Hopkins University, 601 N. Caroline St, JHOC 5223, Baltimore, MD, USA
| | - Varun Puvanesarajah
- Department of Orthopedic Surgery, The Johns Hopkins University, 601 N. Caroline St, JHOC 5223, Baltimore, MD, USA
| | - Micheal Raad
- Department of Orthopedic Surgery, The Johns Hopkins University, 601 N. Caroline St, JHOC 5223, Baltimore, MD, USA
| | - Matthew W Wilkening
- Department of Orthopedic Surgery, The Johns Hopkins University, 601 N. Caroline St, JHOC 5223, Baltimore, MD, USA
| | - Amit Jain
- Department of Orthopedic Surgery, The Johns Hopkins University, 601 N. Caroline St, JHOC 5223, Baltimore, MD, USA
| | - David B Cohen
- Department of Orthopedic Surgery, The Johns Hopkins University, 601 N. Caroline St, JHOC 5223, Baltimore, MD, USA
| | - Brian J Neuman
- Department of Orthopedic Surgery, The Johns Hopkins University, 601 N. Caroline St, JHOC 5223, Baltimore, MD, USA
| | - Khaled M Kebaish
- Department of Orthopedic Surgery, The Johns Hopkins University, 601 N. Caroline St, JHOC 5223, Baltimore, MD, USA.
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Bokov A, Pavlova S, Bulkin A, Aleynik A, Mlyavykh S. Potential contribution of pedicle screw design to loosening rate in patients with degenerative diseases of the lumbar spine: An observational study. World J Orthop 2021; 12:310-319. [PMID: 34055588 PMCID: PMC8152435 DOI: 10.5312/wjo.v12.i5.310] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 02/15/2021] [Accepted: 03/28/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND The majority of published data report the results of biomechanical tests of various design pedicle screw performance. The clinical relevance and relative contribution of screw design to instrumentation stability have been insufficiently studied. AIM To estimate the contribution of screw design to rate of pedicle screw loosening in patients with degenerative diseases of the lumbar spine. METHODS This study is a prospective evaluation of 175 patients with degenerative diseases and instability of the lumbar spine segments. Participants underwent spinal instrumentation employing pedicle screws with posterior only or transforaminal interbody fusion. Follow-up was for 18 mo. Patients with signs of pedicle screw loosening on computed tomography were registered; logistic regression analysis was used to identify the factors that influenced the rate of loosening. RESULTS Parameters included in the analysis were screw geometry, type of thread, external and internal screw diameter and helical pitch, bone density in Hounsfield units, number of levels fused, instrumentation without anterior support, laminectomy, and unilateral and bilateral total facet joint resection. The rate of screw loosening decreased with the increment in outer diameter, decrease in core diameter and helical pitch. The rate of screw loosening correlated positively with the number of fused levels and decreasing bone density. Bilateral facet joint removal significantly favored pedicle screw loosening. The influence of other factors was insignificant. CONCLUSION Screw parameters had a significant impact on the loosening rate along with bone quality characteristics, the number of levels fused and the extensiveness of decompression. The significance of the influence of screw parameters was comparable to those of patient- and surgery-related factors. Pedicle screw loosening was influenced by helical pitch, inner and outer diameter, but screw geometry and thread type were insignificant factors.
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Affiliation(s)
- Andrey Bokov
- Department of Oncology and Neurosurgery, Federal State Budgetary Educational Institution of Higher Education “Privolzhsky Research Medical University” of the Ministry of Health of the Russian Federation, Nizhniy Novgorod 603000, Russia
| | - Svetlana Pavlova
- Department of Oncology and Neurosurgery, Federal State Budgetary Educational Institution of Higher Education “Privolzhsky Research Medical University” of the Ministry of Health of the Russian Federation, Nizhniy Novgorod 603000, Russia
| | - Anatoliy Bulkin
- Department of Oncology and Neurosurgery, Federal State Budgetary Educational Institution of Higher Education “Privolzhsky Research Medical University” of the Ministry of Health of the Russian Federation, Nizhniy Novgorod 603000, Russia
| | - Alexandr Aleynik
- Department of Oncology and Neurosurgery, Federal State Budgetary Educational Institution of Higher Education “Privolzhsky Research Medical University” of the Ministry of Health of the Russian Federation, Nizhniy Novgorod 603000, Russia
| | - Sergey Mlyavykh
- Department of Oncology and Neurosurgery, Federal State Budgetary Educational Institution of Higher Education “Privolzhsky Research Medical University” of the Ministry of Health of the Russian Federation, Nizhniy Novgorod 603000, Russia
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Dilbone E, Gupta R, Stephens B. Analyzing parsicle screws as a viable alternative to pars screws and pedicle screws for C2 posterior instrumentation fixation. J Orthop 2021; 25:220-223. [PMID: 34045826 DOI: 10.1016/j.jor.2021.05.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Accepted: 05/07/2021] [Indexed: 11/29/2022] Open
Abstract
Introduction This study examined the possible clinical utility of "parsicle screws" in securing C2 instrumentation. Methods Ten patients' C2 vertebrae were virtually reconstructed using computer-aided design software. Pedicle, pars, and parsicle screws were virtually placed in the vertebrae. Results In addition to establishing the trajectory and theoretical safety of parsicle screws, this study determined that parsicle screws were significantly longer than pars screws (p = 0.005). Conclusion The additional length of parsicle screws may improve construct stability. As such, parsicle screws should be examined as an alternative to pars screws in patients unable to receive C2 pedicle screws.
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Affiliation(s)
- Eric Dilbone
- Department of Orthopaedic Surgery, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Rishabh Gupta
- Department of Orthopaedic Surgery, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Byron Stephens
- Department of Orthopaedic Surgery, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
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Petrone B, Albano J, Stockton R, Atlas AM, Aronica C, Grewal K. Demographic Analysis of Pedicle Diameter, and Estimated Pedicle Screw Length of the Lumbar Spine in a Diverse Population. Int J Spine Surg 2021; 15:259-265. [PMID: 33900983 DOI: 10.14444/8035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Recent literature confirms the importance of understanding the variability in pedicle morphology among races. These studies suggest that more detailed and reliable measurements of pedicles should be undertaken. However, there is limited data on average pedicle diameters (PDs) or estimated pedicle screw lengths (EPSLs) between diverse racial populations. We sought to determine the differences in PD and EPSL in the lumbar spine between various races: "Asian," "Black," "White," and "Hispanic" to aid in perioperative planning during instrumented spinal fusion. METHODS Axial cuts of 404 patients were inspected to obtain their transverse outer cortical PD as measured through the isthmus, and EPSL by measuring the posterior entry point at the longest distance, which perpendicularly transected the measured isthmic diameter, to the anterior vertebral cortex from L1 to L5. We examined the average PD and PD range at each level for each race. To determine the significance, we used a mixed analysis of variance and a post hoc analysis. RESULTS In this retrospective chart review the races were found to be significantly different in PD and EPSL (P < .001). Post hoc analysis using Dunn-Bonferroni correction showed that Asians had significantly smaller PDs than Blacks and Whites (P < .002 and P < .014, respectively). The White and Hispanic population had significantly longer EPSLs when compared to Blacks and Asians from L1 to L5 (P < .01). CONCLUSIONS This study demonstrates that there are significant differences in pedicle morphology among races that must be taken into consideration when inserting pedicle screws during lumbar spinal fusion. Knowledge of these differences is of the utmost importance in order to limit complications while improving fixation. LEVEL OF EVIDENCE 3. CLINICAL RELEVANCE Pedicle morphology is variable between races and understanding these differences is important for the safe placement of pedicle screws.
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Affiliation(s)
- Brandon Petrone
- Department of Orthopedic Surgery, Northwell Health Plainview Hospital, Plainview, New York
| | - Joseph Albano
- Department of Orthopedic Surgery, Northwell Health Plainview Hospital, Plainview, New York
| | - Robert Stockton
- Department of Orthopedic Surgery, Northwell Health Plainview Hospital, Plainview, New York
| | - Aaron M Atlas
- Department of Orthopedic Surgery, Northwell Health Plainview Hospital, Plainview, New York
| | - Courtney Aronica
- Department of Orthopedic Surgery, Northwell Health Plainview Hospital, Plainview, New York
| | - Kanwarpaul Grewal
- Department of Orthopedic Surgery, Northwell Health Plainview Hospital, Plainview, New York
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Sensale M, Vendeuvre T, Schilling C, Grupp T, Rochette M, Dall'Ara E. Patient-Specific Finite Element Models of Posterior Pedicle Screw Fixation: Effect of Screw's Size and Geometry. Front Bioeng Biotechnol 2021; 9:643154. [PMID: 33777914 PMCID: PMC7990075 DOI: 10.3389/fbioe.2021.643154] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 02/18/2021] [Indexed: 11/13/2022] Open
Abstract
Pedicle screw fixation is extensively performed to treat spine injuries or diseases and it is common for thoracolumbar fractures. Post-operative complications may arise from this surgery leading to back pain or revisions. Finite element (FE) models could be used to predict the outcomes of surgeries but should be verified when both simplified and realistic designs of screws are used. The aim of this study was to generate patient-specific Computed Tomography (CT)-based FE models of human vertebrae with two pedicle screws, verify the models, and use them to evaluate the effect of the screws' size and geometry on the mechanical properties of the screws-vertebra structure. FE models of the lumbar vertebra implanted with two pedicle screws were created from anonymized CT-scans of three patients. Compressive loads were applied to the head of the screws. The mesh size was optimized for realistic and simplified geometry of the screws with a mesh refinement study. Finally, the optimal mesh size was used to evaluate the sensitivity of the model to changes in screw's size (diameter and length) and geometry (realistic or simplified). For both simplified and realistic models, element sizes of 0.6 mm in the screw and 1.0 mm in the bone allowed to obtain relative differences of approximately 5% or lower. Changes in screw's length resulted in 4-10% differences in maximum deflection, 1-6% differences in peak stress in the screws, 10-22% differences in mean strain in the bone around the screw; changes in screw's diameter resulted in 28-36% differences in maximum deflection, 6-27% differences in peak stress in the screws, and 30-47% differences in mean strain in the bone around the screw. The maximum deflection predicted with realistic or simplified screws correlated very well (R 2 = 0.99). The peak stress in screws with realistic or simplified design correlated well (R 2 = 0.82) but simplified models underestimated the peak stress. In conclusion, the results showed that the diameter of the screw has a major role on the mechanics of the screw-vertebral structure for each patient. Simplified screws can be used to estimate the mechanical properties of the implanted vertebrae, but the systematic underestimation of the peak stress should be considered when interpreting the results from the FE analyses.
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Affiliation(s)
- Marco Sensale
- Ansys France, Lyon, France.,Department of Oncology and Metabolism, Mellanby Centre for Musculoskeletal Research, University of Sheffield, Sheffield, United Kingdom.,INSIGNEO Institute for in Silico Medicine, University of Sheffield, Sheffield, United Kingdom
| | - Tanguy Vendeuvre
- Spine and Neuromodulation Functional Unit, Poitiers University Hospital, Poitiers, France.,PRISMATICS Lab (Predictive Research in Spine/Neuromodulation Management and Thoracic Innovation/Cardiac Surgery), Poitiers University Hospital, Poitiers, France
| | | | - Thomas Grupp
- Aesculap AG, Research and Development, Tuttlingen, Germany.,Department of Orthopaedic Surgery, Physical Medicine and Rehabilitation, Ludwig Maximilians University of Munich, Munich, Germany
| | | | - Enrico Dall'Ara
- Department of Oncology and Metabolism, Mellanby Centre for Musculoskeletal Research, University of Sheffield, Sheffield, United Kingdom.,INSIGNEO Institute for in Silico Medicine, University of Sheffield, Sheffield, United Kingdom
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Pehlivanoglu T, Erdag Y, Oltulu I, Akturk UD, Korkmaz E, Yildirim K, Sarioglu E, Gun K, Ofluoglu E, Aydogan M. Unilateral Posterior Surgery for Severe Osteoporotic Vertebrae Fractures' Sequelae in Geriatric Population: Minimum 5-Year Results of 109 Patients. Neurospine 2021; 18:319-327. [PMID: 33657776 PMCID: PMC8255769 DOI: 10.14245/ns.2040812.406] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 01/25/2021] [Indexed: 11/21/2022] Open
Abstract
Objective This study aimed to evaluate the efficacy and safety of modified posterior vertebral column resection (PVCR) combined with anterior column restoration in elderly patients presenting with thoracic or thoracolumbar osteoporotic fractures with spinal cord compression and severe pain.
Methods One hundred nine patients with one level thoracolumbar osteoporotic fracture and at least 5 years of follow-up were included. They underwent posterior instrumentation performed with polymethymetachrylate augmented pedicle screws. A modified PVCR (unilateral costotransversectomy+hemilaminectomy) combined with the insertion of an expandable titanium cage for anterior column restoration was undertaken. Patients were evaluated clinically and radiographically.
Results Patients had a mean age of 74.1 and a follow-up duration of 92.3 months. Mean duration of operations, hospital stays, and mean loss of blood were 172.3 minutes, 4.3 days, and 205.4 mL. All of the patients were mobilized immediately after surgery. The mean preoperative local kyphosis angle improved from 39.3° to 4.7° at the last follow-up (p = 0.003). Patients preoperative mean visual analogue score, Japanese Orthopaedic Association, and Oswestry Disability Index scores improved from 7.7/8.6/76.3 to 1.6/26.1/17.4 (p < 0.001 for all), respectively. The average 36-item Short-Form survey physical component summary/mental component summary scores at the last follow-up were 55.1/56.8. A dural tear was detected intraoperatively in 1 patient and repaired immediately.
Conclusion Subtotal PVCR combined with the insertion of an expandable titanium cage was detected as a safe and effective method for osteoporotic vertebrae fractures’ sequelae in the older population involving spinal cord compression by enabling the decompression of the spinal canal and reconstruction of the resected segment, resulting in significant improvement in clinical and radiographic outcomes.
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Affiliation(s)
- Tuna Pehlivanoglu
- Yeni Yuzyil University, Faculty of Health Sciences, Istanbul, Turkey.,Emsey Hospital, Advanced Spine Surgery Center, Istanbul, Turkey
| | - Yigit Erdag
- Emsey Hospital, Advanced Spine Surgery Center, Istanbul, Turkey
| | - Ismail Oltulu
- Emsey Hospital, Advanced Spine Surgery Center, Istanbul, Turkey
| | | | - Emre Korkmaz
- Emsey Hospital, Advanced Spine Surgery Center, Istanbul, Turkey
| | - Kerem Yildirim
- Emsey Hospital, Advanced Spine Surgery Center, Istanbul, Turkey
| | - Ender Sarioglu
- Emsey Hospital, Advanced Spine Surgery Center, Istanbul, Turkey
| | - Kerem Gun
- Emsey Hospital, Advanced Spine Surgery Center, Istanbul, Turkey
| | - Ender Ofluoglu
- Emsey Hospital, Advanced Spine Surgery Center, Istanbul, Turkey
| | - Mehmet Aydogan
- Emsey Hospital, Advanced Spine Surgery Center, Istanbul, Turkey
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