Pedicle screw instrumentation is a critical technique in spinal surgery, offering effective stabilization for various spinal conditions. However, the impact of intraoperative imaging quality-specifically the use of both anteroposterior (AP) and lateral views-on surgical outcomes remains insufficiently studied. Evaluating whether the adequacy of these imaging modalities affects the risk of unplanned returns to theatre (URTT) within 90 days due to screw malplacement is essential for refining surgical practices and improving patient care.

To evaluate how intraoperative imaging adequacy influences unplanned return-to-theatre rates, focusing on AP and lateral fluoroscopic views.

This retrospective cohort study analyzed 1335 patients who underwent thoracolumbar and sacral pedicle screw instrumentation between January 2013 and December 2022. Data on intraoperative imaging adequacy, screw placement, and URTT events were collected and statistically analyzed using IBM SPSS v23. Imaging adequacy was assessed based on the presence of both AP and lateral views, and outcomes were compared between imaging groups.

A total of 9016 pedicle screws were inserted, with 82 screws identified as malplaced in 52 patients. Of these, 46 patients required URTT due to screw malplacement, with 37 returning within 90 days (URTT90). Patients with both AP and lateral imaging saved intraoperatively had significantly lower URTT90 rates compared to those with only lateral imaging saved, demonstrating the critical role of imaging adequacy in improving surgical outcomes.

This study underscores that comprehensive intraoperative imaging with both AP and lateral views reduces unplanned returns, improves outcomes, enhances precision, and offers a cost-effective approach for better spinal surgery results.

Although idiopathic scoliosis is a common three-dimensional deformity, there is a lack of studies evaluating the associations between the aortic-vertebral distance (AVD) and spinal deformities in all planes. The study therefore aimed to evaluate how the coronal and sagittal curvature, vertebral rotation and aortic-vertebral angle (AVA) affect the AVD in idiopathic scoliosis.

The AVD, AVA, vertebral rotation and curve angles were measured on preoperative magnetic resonance imaging and radiographs in 46 patients who underwent posterior spinal fusion with pedicle screw instrumentation for idiopathic scoliosis Lenke types 1 and 2. Associations between variables were examined using correlation and multivariable regression analyses.

A significant weak to strong correlation was found between the AVD and AVA, and the AVD and vertebral rotation (r = 0.315 to 0.712) within the thoracic curve. The sagittal kyphosis and coronal Cobb angles showed weak correlations with the AVD (r = -0.311 to 0.338). The regression model for the apical vertebral level, which included the four variables, explained 40% (R²=0.40) of the variation in AVD. AVA and vertebral rotation were significantly associated with AVD (p < 0.01 for each), together accounting for 34% (R²=0.34) of the variation.

The shortest distance from the aortic wall to the vertebral body wall is primarily influenced by vertebral rotation and the AVA within the thoracic curve. Thus, these factors need to be taken into consideration when planning pedicle screw placement especially in freehand techniques.

To investigate the safety and accuracy of robot-assisted pedicle screw placement in adolescent idiopathic scoliosis (AIS) surgery.

PubMed, Medline, Embase, Cochrane Library, Web of Science, CNKI, and EMCC databases were searched for studies utilizing the clinical data of adolescent idiopathic scoliosis patients (robot-assisted and fluoroscopy-assisted group) who underwent posterior pedicle screw fixation to collect preoperative, postoperative and follow-up indexes and imaging parameters, including screw implantation accuracy, the number of intraoperative fluoroscopy times, amount of bleeding, operation time, postoperative VAS score and postoperative Cobb angle.

Six studies were included in this meta-analysis, including 154 patients in the intervention group and 171 patients in the control group. Our results showed that screw implantation accuracy (WMD 1.07, 95% CI (1.01,1.14), P = 0.03) was higher than that in the control group. The number of intraoperative fluoroscopy times (WMD -6.11, 95% CI (-9.60, -2.62), P = 0.0006) and operation time (WMD 31.52, 95% CI (5.70,57.35), P = 0.02) in the robot group were less, and the differences were statistically significant. Intraoperative blood (WMD -59.05, 95% CI (-212.81,94.70), P = 0.45), postoperative VAS score (WMD -0.07, 95% CI (-0.24,0.11), P = 0.46), preoperative Cobb angle (WMD 0.79, 95% CI (-1.12,2.69), P = 0.42) (Fig. 7), postoperative Cobb angle (WMD -0.25, 95% CI (-1.12,0.62), P = 0.57) (Fig. 8) had no statistical significance in the robot group compared with control group.

The robot navigation system can improve screw implantation accuracy and reduce the operation time and radiation exposure during the operation.

A systematic review and meta-analysis.

The complexity of human anatomical structures and the variability of vertebral body structures in patients with scoliosis pose challenges in pedicle screw placement during spinal deformity correction surgery. Through technological advancements, robots have been introduced in spinal surgery to assist with pedicle screw placement.

A systematic search was conducted using PubMed, Cochrane, Embase, and CNKI databases and comparative studies assessing the accuracy and postoperative efficacy of pedicle screw placement using robotic assistance or freehand techniques in patients with scoliosis were included. The analysis evaluated the accuracy of screw placement, operative duration, intraoperative blood loss, length of postoperative hospital stay, and complications.

Seven studies comprising 584 patients were included in the meta-analysis, with 282 patients (48.3%) in the robot-assisted group and 320 (51.7%) in the freehand group. Robot-assisted placement showed significantly better clinically acceptable screw placement results compared with freehand placement (odds ratio [OR]: 2.61, 95% confidence interval [CI]: 1.75-3.91, P < 0.0001). However, there were no statistically significant differences in achieving "perfect" screw placement between the two groups (OR: 1.52, 95% CI: 0.95-2.46, P = 0.08). The robot-assisted group had longer operation durations (mean deviation [MD]: 43.64, 95% CI: 22.25-64.74, P < 0.0001) but shorter postoperative hospital stays (MD: - 1.12, 95% CI: - 2.15 to - 0.08, P = 0.03) than the freehand group. There were no significant differences in overall complication rates or intraoperative blood loss between the two groups. There was no significant difference in Cobb Angle between the two groups before and after operation.

Robot-assisted pedicle screw placement offers higher accuracy and shorter hospital stay than freehand placement in scoliosis surgery; although the robotics approach is associated with longer operative durations, similar complication rates and intraoperative blood loss.

With the increasing number of surgeries for pediatric spinal deformities, the aim has been to reduce the associated complications, such as those caused by screw malposition. This case series is an intra-operative experience with a new navigated high-speed revolution drill (Mazor Midas, Medtronic, Minneapolis, MN) for pediatric spinal deformity to assess accuracy and workflow. 88 patients, ranging from 2 to 29 years of age, were included who underwent posterior spinal fusion with the navigated high-speed drill. Diagnoses, Cobb angles, imaging, surgical time, complications, and total number of screws placed are described. Screw positioning was evaluated using fluoroscopy, plain radiography, and CT. Mean age was 15.4 years old. Diagnoses included 47 adolescent idiopathic scoliosis, 15 neuromuscular scoliosis, 8 spondylolisthesis, 4 congenital scoliosis, and 14 other. The mean Cobb angulation for scoliosis patients was 64° and the mean number of levels fused was 10. 81 patients had registration via intraoperative 3-D imaging and 7 had pre-operative CT scan to fluoroscopy registration. There were a total of 1559 screws with 925 placed robotically. 927 drill paths were drilled with the Mazor Midas. 926 out of 927 drill paths were accurate. The mean surgical time was 304 min with the mean robotic time being 46 min. This is the first intra-operative report to our knowledge documenting the experience with the Mazor Midas drill in pediatric spinal deformity showing decreased skiving potential, decreased torque when drilling, and lastly increased accuracy. Level of evidence: level III.

This study assesses intraoperative efficacy, accuracy, and complications of pedicle screw placement using robotic-assisted navigation (RAN) in pediatric spine surgery.

A retrospective review of patients who underwent spine deformity surgery using RAN at a single pediatric institution from 2019 to 2021 was conducted. Patient demographics, perioperative metrics, screw execution and accuracy, technical difficulties, and other outcomes were summarized. In cases with postoperative computed tomography scans, screws were classified using the Gertzbein and Robbins classification scale. Fisher exact tests were used to assess the relationship between procedural changes and lateral screw malposition.

One hundred sixty-two cases with an average patient age of 15.1 years (range, 4 to 31 y) were reviewed. The most common diagnosis was adolescent idiopathic scoliosis (n=80) with an average major curve of 65 degrees. Of 1467 screws attempted, 1461 were executed successfully (99.6%). All failures were in Type D pedicles and were lateral deviations recognized with routine intraoperative fluoroscopy. In cases with postoperative computed tomography imaging, 100% of screws (n=197) were placed with complete containment (Grade A). Remaining screws were graded as accurate by mirroring fluoroscopy and planned computer software positions. In 4% of cases, loss of registration was detected by a safety check before drilling at the planned level. There were no neurological deficits or returns to the operating room. Two changes occurred as part of the learning curve associated with this technique. (1) Adoption of a high-speed navigated drill: Change 1 (last 74 cases). (2) Drilling all pilot holes robotically first, then placing screws within the robotically established tracts to avoid motion and subsequent registration disruption: Change 2 (last 39 cases). Change 1 was less likely to result in screw malposition as no screws skived lateral with the technique ( P =0.03). Change 2 trended toward statistical significance for avoidance of screw malposition and loss of registration, as no loss of registration occurred after adopting this technique.

This study highlights the safety and screw accuracy associated with the use of RAN in pediatric patients.

Level III.

(1) Background: Robotics coupled with navigation (RAN) is a modern surgical platform shown to increase screw placement accuracy during pediatric scoliosis surgery. Our institution uses a technique which combines the RAN platform for apical pedicle screw placement and the freehand (FH) technique for terminal pedicle screw placement during scoliosis surgery (termed hybrid technique). We question if the complementary use of the RAN technology affects intraoperative outcomes, relative to the FH-only approach. (2) Methods: 60 adolescent idiopathic scoliosis (AIS) patients, ages 11−19 at surgery, who were operated on from 2019 through 2020 by a single surgeon, were retrospectively reviewed. Patients were separated by surgery type (hybrid RAN or FH), matched on demographic and surgical factors, and their intraoperative outcomes were compared statistically. (3) Results: Hybrid RAN patients had more screws placed (p = 0.01) and were of a higher BMI percentile (p = 0.005). Controlling for the number of screws placed, BMI%, and initial curve magnitude, there were no statistical differences in estimated blood loss per screw (p = 0.51), curve correction (p = 0.69), complications (p = 0.52), or fluoroscopy time (p = 0.88), between groups. However, operative time was two minutes longer per screw for hybrid RAN patients (p < 0.001). (4) Conclusions: Hybrid RAN surgeries took longer than FH, but yielded comparable effectiveness and safety as the FH technique during the initial RAN adoption phase.

Systematic review and meta-analysis.

Various methods of pedicle screw (PS) placement in spinal fusion surgery existed, which can be grouped into conventional freehand (FH), modified freehand (MF), and image-guided methods (including fluoroscopy-based navigation (FL), computed tomography-based navigation (CT-nav), robot-assisted (RA), and ultrasound-guided (UG)). However, the literature showed mixed findings regarding their accuracy and complications. This review aimed to discover which method of PS placement has the highest accuracy and lowest complication rate in pediatric and adolescent spinal fusion surgery.

A comprehensive search in MEDLINE (PubMed), EMBASE (OVID), CENTRAL, and Web of Science was conducted until May 2020 by 2 independent reviewers, followed by bias assessment with ROB 2 and ROBINS-I tools and quantification with meta-analysis. Overall evidence quality was determined with GRADE tool.

Four RCTs and 2 quasi-RCTs/CCTs comprising 3,830 PS placed in 291 patients (4-22 years old) were analyzed. The lowest accuracy was found in FH (78.35%) while the highest accuracy was found in MF (95.86%). MF was more accurate than FH (OR 3.34 (95% CI, 2.33-4.79), P < .00 001, I2 = 0%). Three-dimensional printed drill template (as part of MF) was more accurate than FH (OR 3.10 (95% CI, 1.98-4.86), P < .00 001, I2 = 14%). Overall, complications occurred in 5.84% of the patients with 0.34% revision rate. Complication events in MF was lower compared to FH (OR 0.47 (95% CI, 0.10-2.15), P = .33, I2 = 0%).

Meta-analysis shows that MF is more accurate than FH in pediatric and adolescent requiring PS placement for spinal fusion surgery.

In contrast to infection and curve progression, return to OR for implant malposition is potentially within the surgeon's control. With increasing surgeon familiarity with freehand/fluoroscopic pedicle screw placement, rates of return to OR due to malposition may have decreased over time. We sought to document the incidence and risk factors for return to OR due to screw malposition in a large cohort of patients with idiopathic scoliosis.

AIS patients enrolled in a multicenter prospective registry with minimum 2-year follow-up undergoing PSF between 2003 and 2017 were included. Surgeries with the use of intraoperative CT-guided navigation were excluded. Return to OR due to screw malposition over time was tabulated. Lenke class, age at surgery, year of surgery, height, weight, surgeon and site were evaluated.

2435 patients underwent PSF with non-navigated open pedicle screw instrumentation. Mean age was 14.6 years, mean thoracic curve magnitude was 53°, and mean lumbar was 40°. Patients did not routinely undergo intraoperative or postoperative CT evaluation. There were 10 returns to OR for screw malposition at a mean of 0.83 years postoperatively (range 0.1-3.4 years), for an overall incidence of 0.4%. Of the 14 screws, 10 were thoracic, 7 were left-sided. No association was found between screw malposition and curve size, enrolling site, surgeon, BMI, Lenke class, or age. Five patients had radiculopathy which improved after screw revision. Return to OR for screw malposition changed from 2003 to 2017 (1-0.2%) but this did not reach statistical significance.

Although the incidence of asymptomatic malpositioned screws is unknown, the rate of return to the OR for implant malposition overall in this registry was 1 in 250 patients. Recent data suggest the rate has decreased to 1 in 500 patients. Further work may determine whether enabling technologies can reduce the rate, ideally to a "never event".

Although pediatric spinal deformity correction using pedicle screws has a very low rate of complications, the long-term consequences of screw malposition is unknown. CT navigation has been proposed to improve screw accuracy. The aim of this study was to determine whether intraoperative navigation during pedicle screw placement in pediatric scoliosis makes screw placement more accurate. We also examined radiation exposure, operative time blood loss and complications with and without the use of CT navigation in pediatric spinal deformity surgery.

A systematic review of the literature was conducted. After screening, 13 articles were qualitatively and quantitatively analyzed to be used for the review. A random effects meta-analysis using REML methodology was employed to compare outcomes of screw accuracy, estimated blood loss, radiation exposure, and surgical duration.

Screws placed with CT navigation surgery were three times as likely to be deemed "acceptable" compared with screws placed with freehand and 2D fluoroscopy assistance, twice as likely to be "perfect", and only 1/3 as likely to be potentially unsafe (all p value < 0.01). EBL was not significantly different between groups; however, operative time was roughly thirty minutes longer on average. Random effects analysis showed no significant difference in effective dose radiation while using CT navigation (p = 0.06).

This systematic review of the literature demonstrates that intraoperative navigation results in more accurate pedicle screw placement compared to non-navigated techniques. We found that blood loss was similar in navigated and non-navigated surgery. Operative time was found to be approximately a half hour longer on average in navigated compared to non-navigated surgery. Effective radiation dose trended higher in navigated cases compared to non-navigated cases but did not reach statistical significance.

Aortic injury is a rare, yet underreported and underestimated complication of spine surgery. Anatomical relation between the aorta and the spine changes under physiological (positional) as well as pathological (deformity) conditions, which puts the aorta at risk of injury during spine surgery. Clinical presentation of aortic injury ranges from asymptomatic perforation of the aorta to acute fatal bleeding. Although several diagnostic methods have been reported, CT-angiography remains an important diagnostic study. Several advancements in the open and the endovascular surgical management have been reported to be successfully used in the management of aortic injury following spine surgery. Management approach of malpositioned screws abutting the aorta is still controversial. Anatomical knowledge and understanding of the previously reported mechanisms of aortic injury are important to be integrated in the preoperative planning process. If the complication occurs, time-to- recognition and to-appropriate-management are important factors for predicting mortality. If unrecognized and untreated in the acutely injured patients, mortality can approach 100%.

O-arm assisted pedicle screw placement has been proven to be more accurate than free-hand technique. Radiation exposure remains the primary drawback. We determined the feasibility and safety of a reduced radiation protocol in paediatric patients undergoing scoliosis correction.

A reduced radiation protocol for a medtronic O-arm navigational system was devised. 3D CT reconstructions of an anthropomorphic pelvic phantom indicated adequate image quality after reduction to 14% of current manufacturer default factors. A feasibility study to test the image quality was undertaken on four patients, one with syndromic and three with idiopathic scoliosis each receiving progressively reducing radiation exposure of 60%, 50%, 40% and 14% of what would have been delivered using the manufacturer default protocol. This represented 32% of the mayo clinic protocol. It was achieved by reducing the x-ray tube current to 10 mA while keeping the tube potential at 90 kVp.

A low dose O-arm protocol was able to generate adequate image quality while delivering as little as 14% (for lumbar region reconstructions) of the recommended protocol radiation dose. The total radiation dose delivered with this protocol was approximately 0.8 milliSieverts for a single spin. This effective dose represents < 1/3 of average UK and < 1/6 average US annual radiation exposure. There were no neurological or implant-related complications.

Our low dose O-arm radiation protocol significantly reduces the radiation exposure compared to the manufacturer recommended Mayo clinic protocol providing operational image quality to allow accurate screw placement in spinal deformity.

We sought to investigate the changed position of thoracic aorta relative to spine in patients with left thoracic scoliosis and to analyze the potential risks of thoracic aorta injury from pedicle screw insertion in these patients.

Twenty patients with left thoracic scoliosis (Group A) and 15 normal subjects with a straight spine (Group B) were included. Axial computed tomography images from T5 to T12 of all these subjects were obtained to measure the aorta-vertebral angle. The percentages of thoracic aorta located anteriorly to the screw trajectory were calculated on both the left and right sides.

The average aorta-vertebral angle in Group A was significantly larger than that in Group B at each level (P < 0.05) except T5. In Group A, both left and right pedicle screws might pose threats to the thoracic aorta. The percentages of aortas at risk from the right pedicle screw were high in the apical region. However, in Group B, only the left pedicle screw might pose threats to the aorta. No aorta was found to be at risk of injury from right pedicle screw insertion in Group B.

The thoracic aorta often lies anteriorly to the left pedicle screw trajectory in normal subjects, especially in the lower thoracic region. However, the thoracic aorta moves to the right side in patients with left thoracic scoliosis, making a large proportion of patients at risk of injury from right pedicle screw insertion in the apical region.

Case reports and review of the literature with a proposed management algorithm.

To report two cases of a potential vascular complication due to an incorrectly placed pedicle screw (PS) during spine deformity surgery. Relevant literature regarding the management of vascular complications is reviewed, and an evidence-based management algorithm is proposed. Aortic lesions represent a rare but potentially life-threatening complications with spine deformity and revision surgery, significantly increasing the risk. A management algorithm for an aortic lesion in the case of a malpositioned PS has not yet been published.

Case 1: An 18-year-old female with proximal thoracic spinal non-instrumented fusion underwent a revision corrective procedure due to a progressive right-sided thoracolumbar compensatory curve. However, postoperative computed tomography (CT) performed to evaluate the position of the PS revealed malposition of the left T9 PS, which was abutting the descending aorta with CT angiography excluding the perforation of the aorta. Case 2: A 17-year-old male was scheduled for correction of Lenke 3-C-N adolescent idiopathic scoliosis. Postoperative routine evaluation with low-dose CT revealed a left T9 PS paravertebral malposition, and subsequent CTA demonstrated that the thread of the PS was in contact with the descending thoracic aorta and an unlikely hemodynamically significant vessel injury.

Successful removal of both malpositioned PS was performed. In the first case, a cardiovascular surgeon attended the operation if an urgent thoracotomy was needed, and in the second case, additional video-assisted thoracoscopic control of the aorta was performed during PS removal.

Preoperative imaging in spinal surgery is essential to avoid major vascular and other complications when placing PS, especially in thoracic deformities. When a potential major vessel complication emerges, an interdisciplinary approach and an appropriate management algorithm are mandatory to make the best clinical decisions.

4.

Through the comparison of three-dimensional CT reconstruction between the supine position and the prone position, the relative position of thoracolumbar great vessels and vertebral body was studied, and the shortest safe distance between them was measured to improve the safety of bicortical pedicle screw insertion and reduce the risk of vascular injury.

Forty adults were selected to participate the research. Three-dimensional reconstruction of thoracolumbar (T9-L3) CT was performed in the prone position and the supine position. The relative distance between the Aorta/Inferior Vena Cava (IVC) and vertebral body was obtained as AVD/VVD respectively. The relative angle of the Aorta/ IVC and the vertebral body was calculated as ∠AOY/∠VOY. Self-controlled experiments were carried out in the prone and the supine positions, and the data obtained were analyzed using SPSS 22.0 statistical software.

The AVD of the prone position and the supine position was the shortest at T12 (3.18 ± 0.68 mm), but the difference was not statistically significant. The aorta of the T9-L3 segment was shifted from the anterolateral to the anteromedial. The ∠AOY of the other groups differed significantly between the prone and supine positions in all vertebrae except T12 and L1 (P < 0.05), and the aorta in the prone position was more anteromedial than that of supine position. With regard to VVD/∠VOY, there was no significant difference between the prone and supine positions (P ≥ 0.05), and the minimum VVD of L3 segment is greater than 5.4 mm. The IVC has no obvious mobility and is fixed in the range of 20 ° ~ 30 ° near the midline.

When using bicortical anchoring of pedicle screws, it is safe to ensure that the protruding tips of the screw is less than 3 mm. Due to the mobility of the aorta in different postures and individual differences in anatomy, the prone position CT can help doctors to make better preoperative plans and decisions.

To report delayed onset common iliac artery perforation and infected pseudoaneurysm caused by malpositioned pedicle screw after minimally invasive scoliosis surgery (MISS).

A 21-year-old female was referred to our hospital with a 1-week history of abrupt right-sided low back pain, lower abdominal pain, and fever with a history of MISS using cannulated pedicle screws 18 months earlier. Paravertebral arterial erosion with pseudoaneurysm and retroperitoneal and paraspinal abscess were suspected.

We performed resection of the pseudoaneurysm, vascular repair of right common iliac artery by angioplasty with a bovine patch and removal of implant. At 6 months after the last surgery, she had no limitations or problems in her daily activities with no recurrence of low back pain, abdominal pain, or fever as well as without loss of deformity.

Our case showed that misplaced pedicle screws can cause potentially fatal complications, such as infected pseudoaneurysm, even in the late postoperative period.

Transpedicular screw insertion has become widely accepted for the correction of spinal deformity as well as degenerative and traumatic injury, but adoption of this technique has remained less widespread in the thoracic compared to the lumbar spine. This is thought to be associated with the relative technical difficulty of screw insertion into the narrower widths of the thoracic pedicles and the neurologic and mechanical risks associated with breach of the pedicle wall. The surgical decision making involves determining the appropriate sized screw for maximum fixation strength while simultaneously respecting the structural integrity of the vertebral pedicles to prevent a breach and provide better fixation. This paper presents a systematic review of criteria for thoracic pedicle screw diameter (SD) selection in order to orient inexperienced surgeons on the impact of this selection on pedicle breaching and fixation strength.

We performed a systematic literature review focused on studies reporting SD selection in relation to pedicle dimensions, measures of fixation strength, and breach rate.

Twenty-nine articles that measured fixation strength, breach rate, and/or provided SD in relation to pedicle width were selected for inclusion.

A commonly accepted criteria for pedicle SD selection has not yet been proposed. Screw diameters approximately 80% of the pedicle width have been adopted, but this proportion is rarely reported in the midthoracic vertebrae for which smaller pedicles and inadequate hardware specificity result in higher breach rates. Depending upon the insertion technique adopted, greater specificity in diameter selection by vertebral level should be pursued in order to maximally target cortical bone purchase.

Based on this review of the literature, we believe that proper selection of the SD for individual vertebral level directly affects the insertion technique and the potential breach.

We assessed the contribution of a dynamic surgical guidance (DSG) probe in the accurate placement of thoracic and lumbar pedicle screws (PSs) in patients with spinal deformity.

A retrospective review was performed of 98 patients (104 procedures) with various spinal deformities, who had received posterior instrumentation with PSs inserted using either DSG or the conventional free-hand (FH) technique. A total of 882 PSs were inserted using DSG (DSG group) and 603 using the FH technique (FH group). The DSG probe was preferably chosen for large osteosyntheses and severe deformities. Two neurosurgeons, unaware of the surgical groups, reviewed all the intraoperative computed tomography scans and assessed all the PS placements.

Of the PSs used, 95.4% in the DSG group and 92.2% in the FH group were correctly placed (P = 0.0136). The difference in screw placement accuracy was greater at the thoracic level (DSG group, 92.5%; vs. FH group, 87.0%; P = 0.0310) than at the lumbar level (DSG group, 98.0%; vs. FH group, 95.4%; P = 0.0385). Severe (>4 mm) lateral breaches occurred in 24 cases (4.0%) in the FH group but in only 5 (0.6%) in the DSG group (P < 0.0001). No severe medial breach was observed in either group.

Despite having more patients with severe deformities in the DSG group, PS insertion was significantly more accurate with DSG. This technique also reduced the severe unacceptable lateral misplacement rate (>4 mm) and, consequently, the incidence of intraoperative screw revisions even in patients with severe deformities.

The purpose of this study was to analyze the occurrence of PE after intra-operative O-arm navigation-assisted surgery and determine whether the post-operative PE incidence could be decreased by using O-arm navigation as compared to conventional free-hand technique.

A cohort of 27 patients with spinal deformity who were operated upon with an O-arm navigated system (group A) between 2013 and 2016 were enrolled in the study. A total of 27 curve-matched patients treated by conventional free-hand technique were included as the control group (group B). Whole spine posterior-anterior and lateral radiographs, and CT scans were taken pre and post-operation. Radiologic parameters and volume of PE were measured and compared between the two groups.

There were no significant differences in age, Cobb angle, and sagittal contour between the two groups pre-operatively. The mean total volume of post-operative PE was significantly larger in the free-hand group (p < 0.001). In the O-arm group, 59 malpositioned screws were identified in 22 patients. In the free-hand group, 88 malpositioned screws were found among 26 patients. The screw perforation rate was higher in the free-hand group than in the O-arm group (p = 0.007). In the O-arm group, the mean volume of PE was significantly larger among patients with malpositioned screws than those without malpositioned screws (p < 0.001), as well as in the free-hand group.

The volume of PE after correction surgery can be significantly decreased by application of O-arm navigation system as compared to conventional free-hand technique. We ascribed the improvement to the accuracy of screw implantation navigated by O-arm.

MINI: The objective of this study was to determine the safety limits of anterior/anterolateral pedicle screw breaches. Through clinical and cadaveric study, it appears that less than 4 mm of breach has a significantly lower likelihood of impingement on vital structures (P < 0.001).

Clinical retrospective chart review and basic science study.

To determine the safety limits of an anterior/anterorolateral misplaced pedicle screw on computed tomography (CT) scan in spinal deformity.

Although the limits of medial breaches (<4 mm) are known, the safe limits for anterior/anterolateral breaches in spine deformity are not yet defined.

The present study had two parts. In part I, postoperative CT scans of 165 patients operated on for spine deformity were reviewed for screw misplacement (2800 screws). The amount of anterior/anterolateral breach was measured. Protrusions were also evaluated for proximity to vital structures. All scans were reviewed by musculoskeletal radiologist. In part II, eight cadavers were instrumented with 6 × 30 and 6 × 40 mm bilaterally from T1-S1. Screws were randomly inserted under navigation guidance either "IN" or "OUT-anterior/lateral." CT scan was performed, followed by gross dissection to determine screw position.

Part I: 116(4.2%) screws were misplaced anterior/anterolaterally. Thirty-one (26.7%) were adjacent to vital structures. Fisher exact test showed 4 mm or less breach has significantly lower likelihood of impingement (P < 0.001). Screws adjacent/impinging the aorta protruded an average 5.7 ± 0.6 mm, whereas screws not involving the aorta breached an average 3.9 ± 0.2 mm, (P < 0.001). Part II: 285 screws were inserted. On CT scan, 125 were misplaced anterior/anterolaterally. On gross dissection, 89 were visibly misplaced; 23 were covered entirely by soft tissue but were palpable; and 13 were contained in bone. All 23 screws did not endanger any structures and protruded less than 4 mm on CT scan.

Anterior/anterolateral breaches of 4 mm or less on CT poses no significant risk of impingement and therefore can be considered safe.

3.

A retrospective clinical and radiographic study.

The aim of this study was to evaluate outcomes of the key vertebral pedicle screw strategy (KVPSS) for the correction of flexible Lenke type 1 adolescent idiopathic scoliosis (AIS) with a minimum follow-up of 5 years.

The KVPSS has been described as an alternative screw placement strategy for surgically treating the main thoracic curve in AIS patients. However, there have been no long-term, three-dimensional correction studies of selective thoracic fusion using the KVPSS in Lenke type 1AIS.

Twenty consecutive patients with Lenke type 1 main thoracic AIS underwent one-stage posterior correction and fusion using the KVPSS. Preoperative and postoperative radiographic and clinical parameters were analyzed.

The mean preoperative major thoracic curve was 47.4° ± 5.8°, and mean corrections of 67.0%, 63.4%, and 61.5% were observed at the immediate, 2-year postoperative, and final follow-ups, respectively. Thoracickyphosis decreased significantly from the preoperative period to the immediate postoperative period (P = 0.042) but did not change significantly from the 2-year postoperative follow-up to the final follow-up (P = 0.067). Apical vertebral rotation achieved 34.7% correction and exhibited correction loss of 8.2% at the final follow-up. The average intraoperative blood loss was 802.3 mL, and the mean operative time was 138.6 minutes. SRS-22 scores for self-image and satisfaction improved significantly from the preoperative period to the final follow-up. No neurologic or implant-associated complications were observed in this study.

The KVPSS is an effective method for correcting Lenke type 1 AIS and achieves satisfactory correction of the deformity. Relative to other approaches, the KVPSS can not only achieve a satisfactory and cost-effective clinical outcome but also reduce both operative time and intraoperative blood loss.

4.

The surgical management of high-grade spondylolisthesis in adolescents remains a controversial issue. Because the basic procedure, posterolateral fusion, is associated with a significant rate of pseudarthrosis and listhesis progression, there is a pressing need for alternative surgical techniques. In the present report, the authors describe the case of an adolescent patient with significant low-back pain who was found to have Grade IV spondylolisthesis at L5-S1 that was treated with transsacral transdiscal screw fixation. Bilateral pedicle screws were placed starting from the top of the S-1 pedicle, across the L5-S1 intervertebral disc space, and into the L-5 body. At 14 months after surgery, the patient had considerable improvement in his pain and radiographic fusion across L5-S1. The authors conclude that transsacral transdiscal pedicle screws may serve as an efficacious and safe option for the correction of high-grade spondylolisthesis in adolescent patients.

To analyze the occurrence, risk factors, treatment and prognosis of postoperative pleural effusion after spinal deformity correction surgery.

The clinical and imaging data of 3325 patients undergoing spinal deformity correction were collected from the database of our hospital. We analyzed the therapeutic process of the 28 patients who had postoperative pleural effusion, and we identified the potential risk factors using logistic regression.

Among the 28 patients with postoperative pleural effusion, 24 (85.7%) suffered from hemothorax, 2 (7.1%) from chylothorax, and 2 (7.1%) from subarachnoid-pleural fistula. The pleural effusion occurred on the convex side in 19 patients (67.9%), on the concave side in 4 patients (14.3%), and on both sides in 4 patients (14.3%). One patient with left hemothorax was diagnosed with kyphosis. The treatment included conservative clinical observation for 5 patients and chest tube drainage for 23 patients. One patient also underwent thoracic duct ligation and pleurodesis. All of these treatments were successful. Logistic regression analysis showed that adult patients(≥18 years old), congenital scoliosis, osteotomy and thoracoplasty were risk factors for postoperative pleural effusion in spinal deformity correction surgery.

The incidence of postoperative pleural effusion in spinal deformity correction surgery was approximately 0.84% (28/3325), and hemothorax was the most common type. Chest tube drainage treatment was usually successful, and the prognosis was good. Adult patients(≥18 years old), congenital scoliosis, and had undergone osteotomy or surgery with thoracoplasty were more likely to suffer from postoperative pleural effusion.

Pedicle screw constructs have become the mainstay for surgical correction in patients with spinal deformities. To reduce or avoid the risk of pedicle screw-based complications and to decrease the costs associated with pedicle screw instrumentation, some authors have introduced interval, skipped, and key-vertebral pedicle screw strategies for correction. However, there have been no comparisons of outcomes among these 3 pedicle screw-placement strategies.The aim of this study was to compare the correlative clinical outcomes of posterior correction and fusion with pedicle screw fixation using these 3 surgical strategies.Fifty-six consecutive patients with Lenke type 1 adolescent idiopathic scoliosis were included in this study. Twenty patients were treated with the interval pedicle screw strategy (IPSS), 20 with the skipped pedicle screw strategy (SPSS), and 16 with the key-vertebral pedicle screw strategy (KVPSS). Coronal and sagittal radiographs were analyzed before surgery, at 1 week after surgery, and at the last follow-up after surgery.There were no significant differences among the 3 groups regarding preoperative radiographic parameters. No significant difference was found between the IPSS and SPSS groups in correction of the main thoracic curve (70.8% vs 70.0%; P = 0.524). However, there were statistically significant differences between the IPSS and KVPSS groups (70.8% vs 64.9%) and between the SPSS and KVPSS groups (70.0% vs 64.9%) in correction of the main thoracic curve (P < 0.001 for both). Additionally, there were no significant differences among the 3 strategies for sagittal parameters at the immediate postoperative and last postoperative follow-up periods, though there were significant differences in the Cobb angle between the preoperative and immediate postoperative periods among the 3 groups, but not between the immediate postoperative and last follow-up periods. The amount of hospital charges in the SPSS group was significantly higher than those in the IPSS (P < 0.001) and KVPSS groups (P < 0.001). There were also significant differences in operative time between the IPSS and KVPSS groups (P < 0.001) and between the SPSS and KVPSS groups (P < 0.001).Each of the 3 types of pedicle screw strategies for correction in patients with Lenke type 1 adolescent idiopathic scoliosis are effective, with satisfactory coronal and acceptable sagittal plane results. Although the KVPSS does not provide superior operative correction compared with the IPSS and SPSS, it can achieve a satisfactory clinical outcome and is more cost-effective.

Delayed presentation of a thoracic aortic injury is an extremely rare complication after spine surgery. We report a case of delayed presentation of a thoracic aortic injury with a vertebral pedicle screw after posterior spinal surgery without periaortic hematoma, hemorrhage or pseudoaneurysm formation and review the relevant literature.