Utilization of autogenous iliac bone shaped into a low-profile form to repair bone defects following cervical infection: A case report

Abstract

BACKGROUND

Surgical reconstruction of bone defects after cervical spine infection debridement remains challenging due to the limited treatment options available. In this case report, we describe a novel technique using a low-profile, contoured autologous iliac bone graft for the reconstruction of post-debridement bone defects. This approach can effectively reduce the risk of infection, minimize the use of internal fixation devices, and yield favorable clinical outcomes. Our findings demonstrate that low-profile autologous iliac bone grafting is a practically feasible and reliable surgical option for managing bone defects following cervical spine infection debridement.

CASE SUMMARY

A 59-year-old male patient was admitted to the hospital with a complaint of neck pain and limited mobility for over a month. Upon admission, a computed tomography scan was performed and revealed a destruction of the C3 and C4 vertebral bodies. Magnetic resonance imaging was also performed and showed a low signal on T1 and high signal on T2 at the anterior edges of the C3 and C4 vertebral bodies. Next, a puncture biopsy was conducted and the results showed neutrophil infiltration and the formation of purulent lesions. Bacterial culture of aspirated fluid obtained during the cervical puncture biopsy indicated the presence of Streptococcus pharyngitis, and a diagnosis of cervical infection was confirmed, for which antibiotic treatment was administered. On the 12^th day after admission, the patient experienced severe symptoms of nerve compression and underwent surgery through a combined anterior and posterior approach for cervical canal decompression, lesion debridement, bone grafting, fusion, and internal fixation. During the surgery, a cortical autogenous iliac bone block was trimmed into a low-profile bone block to repair the bone defect. After the operation, the patient's neurological symptoms had disappeared. A follow-up X-ray two months later showed that the iliac bone block and vertebral body had fused properly, and the cervical spine had a normal curvature and stability.

CONCLUSION

After debridement of a cervical infection, one option to repair the resulting bone defects is to employ an autogenous iliac bone shaped into a low-profile form. This offers significant advantages and is a practical approach.

Key Words: Cervical infection; Lesion debridement; Low-profile; Iliac autogenous bone; Operation; Bone defect; Case report

Core Tip: Repairing bone defects after debridement for cervical spine infection is challenging. The use of internal fixation is controversial, and suitable bone graft materials are scarce. As a promising option, we applied low-profile contoured autologous iliac bone grafts, and found that they could reduce the infection risk, minimize internal fixation, and achieve rapid osseous fusion and good adaptability with satisfactory clinical outcomes. This technique is practical and feasible for reconstructing bone defects post-debridement in cervical spine infection.

INTRODUCTION

The incidence rate of spinal infection is 2.4 per 100000, with cervical spine infections accounting for less than 11% of all spinal infections[1]. Although cervical infections are not common, they can cause neurological damage and incur a high rate of disability[2]. Therefore, when symptoms of nerve compression appear, surgical treatment should be done promptly[3]. Some researchers advocate for staged surgery, which involves debridement and decompression in the first stage and spinal stability reconstruction in the second stage, to prevent secondary infections caused by the implantation of internal fixation devices in an uncontrolled infection[4]. However, this approach increases the patient's surgical and hospitalization time, also increasing the risk of complications[5]. Other studies suggest that spinal instruments are not an absolute contraindication for one-stage surgery for spinal infections, and that one-stage surgery can achieve both debridement and internal fixation instrument fusion[6].

The primary treatment for cervical infection is debridement and reconstruction of the spinal stability[7]. However, during the initial phase of surgery, to avoid increasing the risk of infection and to ensure the natural curvature and stability of the cervical spine, the options for implant materials to repair bone defects are limited. In clinical practice, titanium mesh cages, synthetic bone grafts, and artificial vertebral bodies are the main implants used for reconstructing bone defects following spinal lesion debridement. However, these grafts generally suffer from inferior biomechanics, insufficient strength, and poor fusion, while metallic internal fixation often causes secondary infection and can suffer from implant loosening issues, leading to surgical failure. In the present case, a patient was admitted to our hospital with an acute exacerbation of a cervical infection and nerve compression. We conducted emergency first-stage surgery, which included posterior cervical decompression and lateral block screw fixation, as well as clearance of the infected lesion through an anterior approach. We used an autogenous iliac bone shaped into a low-profile form to repair the bone defect, thus reducing the need for internal fixation devices. The postoperative effect was satisfactory.

CASE PRESENTATION

Chief complaints

A 59-year-old male patient was admitted to the hospital with a complaint of neck pain and limited mobility for over a month.

History of present illness

One month previously, the patient had developed neck pain with restricted mobility without any obvious cause, and the symptoms had gradually become aggravated. Before presenting at our hospital, the patient had received conservative treatment at another hospital, but had shown no improvement.

History of past illness

Prior to the present complaint, the patient was healthy with no significant past medical history.

Personal and family history

The patient denied any family history of infectious diseases.

Physical examination

Upon physical examination of the patient when presenting at our hospital, limited cervical flexion and extension was observed. Mild local tenderness was present with a visual analog scale (VAS) score of 5. Sensation, muscle strength and muscle tone of the upper and lower extremities were all intact, and the tendon reflexes were found to be normal in all extremities. The cervical compression test, bilateral brachial plexus traction test, Spurling test, and Hoffmann sign were all negative, while the left Babinski sign was positive.

Laboratory examinations

Routine blood tests after admission revealed no obvious abnormalities, and the patient’s complete blood count, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) were all within normal limits.

Imaging examinations

An X-ray of the cervical spine revealed low-density shadows at the front of the C3 and C4 vertebral bodies, a discontinuous bone cortex, and a narrowing of the C3/4 intervertebral space (Figure 1A). Additionally, there was no indication of cervical instability on the X-ray film for cervical flexion and extension. A computed tomography scan revealed destruction of the C3 and C4 vertebral bodies (Figure 1B), while magnetic resonance imaging (MRI) showed a low signal on T1 and high signal on T2 at the anterior edges of the C3 and C4 vertebral bodies, and a horizontal compression of the C3/4 segment of the spinal cord (Figure 1C).

Figure 1 Imaging findings on admission and before surgery. A: X-ray imaging upon admission revealing low-density shadows along the front of the C3 and C4 vertebrae, with an interruption of the bone cortex and a decrease in the C3/4 intervertebral space; B: Computed tomography scan upon admission showing destruction of the bone within the C3 and C4 vertebrae; C: Admission MRI revealing hyperintensity on T2-weighted fat-suppressed images at the anterior margins of the C3 and C4 vertebral bodies, with mild spinal cord compression; D: Preoperative MRI demonstrating hyperintensity on T2-weighted fat-suppressed images involving the C3 and C4 vertebral bodies and intervertebral space, with marked spinal cord compression.

FINAL DIAGNOSIS

Based on the patient's clinical presentation and the bacterial culture results of the aspirated fluid obtained from the cervical puncture biopsy, the final diagnosis was cervical pyogenic infection.

TREATMENT

Sensitive antibiotics, including ceftriaxone sodium and levofloxacin, were administered according to the results from antimicrobial susceptibility testing. Dosage regimen: Levofloxacin 0.5 g intravenously once daily; ceftriaxone 2 g intravenously once daily.

On the twelfth day after admission, the patient’s left deltoid muscle strength suddenly decreased dramatically to grade I (Oxford Grading Scale) muscle strength. A re-examination MRI revealed a narrowing of the C3/4 intervertebral space, with long T1 and T2 signals visible inside, and a high signal intensity on the liposuppression image. The spinal cord was found to be compressed (Figure 1D). Neurological function was classified as American Spinal Injury Association (ASIA) grade B according to the ASIA impairment scale.

It was clear that the patient's condition had advanced quickly, so emergency surgery was done to clear the cervical canal and decompress the nerves. This was done through a combined anterior and posterior approach, which also included bone grafting and internal fixation. First, posterior laminectomy decompression and screw-rod internal fixation were performed. Subsequently, a corticocancellous iliac bone graft (4 cm × 2 cm × 2 cm) was harvested from the left anterior superior iliac spine (ASIS) for interbody grafting. Via an anterior approach, the bony shell of C3/4 anterior osteophytes encasing the intervertebral space was removed. A small amount of thin purulent exudate, inflammatory granulation tissue, and anterior one-third bony destruction of the C3/C4 vertebrae were noted. The granulation tissue was thoroughly curetted for histopathological examination, bacterial culture, and antibiotic susceptibility testing. A 2 cm × 1 cm bone trough was created at C3/4, followed by copious irrigation with hydrogen peroxide, benzalkonium bromide, and normal saline. The iliac graft was trimmed into a low-profile block, then implanted into the C3-4 trough, and fixed with two anterior cervical screws (Figure 2A and B).

Figure 2 Intraoperative, histopathological, and radiographic findings. A and B: Trimming of a cortical iliac bone block into a low profile to match the bone defect, and then its fixation with two screws, for two sides of the bone cortex; C: Pathology following the surgery showed fibrous tissue proliferation, an infiltration of acute and chronic inflammatory cells, and granulation tissue formation, with locally visible fragmented bone tissue; D: X-ray follow-up at 2 months later showing satisfactory fusion between the iliac bone block and the vertebral body, good internal fixation without loosening, and preserved physiological curvature and stability of the cervical spine.

OUTCOME AND FOLLOW-UP

On the second day after the above-described procedure, the patient’s left deltoid muscle strength was tested and found to have returned to level IV, and a sample of the drainage fluid was taken for bacterial culture. On the third day, no drainage fluid was present and the tube was removed. The patient was allowed to ambulate while wearing a neck brace. The pathology results of the tissue sent for intraoperative examination showed fibrous tissue hyperplasia, with acute and chronic inflammatory cells and the formation of granulation tissue, as well as fragmented bone tissue (Figure 2C). The bacterial culture of the intraoperative specimens did not reveal any suspicious pathogens, and no bacteria were found in the postoperative drainage fluid culture. Antibiotics were administered continuously for 6 weeks after surgery. After two months, the patient’s neck pain VAS score was 2, and both upper limb sensations and movements were normal. Follow-up blood examinations showed normal ESR and CRP levels. Re-examination of the cervical spine via X-ray showed a satisfactory fusion of the iliac bone block and vertebral body, with good internal fixation, no looseness, and a good physiological curvature and stability of the cervical spine (Figure 2D).

DISCUSSION

The incidence of cervical spine infection is low and the initial signs are mainly neck pain. Due to its atypical symptoms, it is often hard to diagnose and may be misdiagnosed. As the condition progresses, other symptoms, such as fever, chills, weight loss, and neurological issues, may arise. If pain or fever is the only symptom, the diagnosis could be delayed for up to three months[8]. Enhanced MRI is the best method for diagnosing cervical suppurative infection and is the preferred imaging examination for evaluating, monitoring, and formulating treatment plans[9,10]. Staphylococcus aureus is the most common cause of cervical infection[8]. When the patient has a stable cervical spine, no neurological symptoms, and a clear infection, conservative treatment may be applied[11]. The primary conservative treatments are intravenous antibiotics and a cervical collar[12]. While most guidelines recommend a duration of 6-12 weeks for intravenous antibiotics[13], Bernard et al[14] reported that the duration of antibiotic use can be reduced to 6 weeks.

Surgery is necessary for those with neurological symptoms or serious cervical instability that cannot be treated conservatively[15]. For cervical infection with a combined epidural abscess, surgery via an anterior approach is necessary in order to expose the infected area for thorough debridement and decompression. There is still some dispute over whether internal fixation instruments need to be used to repair bone defects following an anterior approach debridement. Shad et al[16] found that even after a year of using internal fixation instruments to treat cervical infection, bacteria were still detected on the external surface of the internal fixation when it was removed. Studies have shown that bacteria can colonize and form biofilms on the surface of implanted devices, which can impede the body’s immune response and the effectiveness of antibiotics, leading to persistent and recurrent infections[17,18]. Nevertheless, many studies have found that the use of internal fixation instruments is safe and effective[19,20]. Furthermore, following isolated anterior debridement, the efficacy of reconstructing cervical spine stability and restoring cervical physiological lordosis is considerably limited by implant subsidence and other related factors, regardless of whether internal fixation devices are utilized to fill bone defects. Accordingly, additional posterior screw-rod fixation is indispensable to further reinforce stability and prevent kyphotic deformity. An anterior–posterior combined approach surgery is beneficial as it enables complete debridement through the anterior approach, while posterior fixation guarantees the spine’s stability[19].

Currently, the utilization of internal fixation after surgery for cervical spine infection remains controversial. Nevertheless, existing studies have validated the safety of metallic implants in this scenario. For instance, Lu et al[20] confirmed that the application of implants such as allograft bone or titanium cages in spinal infectious diseases (including pyogenic and tuberculous infections) does not increase the risk of recurrent spinal infection. Recently, Shiban et al[21] reported that polyetheretherketone cages are safe and feasible for the management of pyogenic spondylitis. However, bone defects following debridement present irregular and diverse morphologies, and conventional standardized metallic implants often cannot perfectly match these irregular defects. Moreover, further recontouring of the bone defect to accommodate metallic implants inevitably aggravates the severity of bone loss. Autologous iliac bone is unmatched by other bone graft substitutes due to its excellent malleability, osteoinductivity, and osteogenic capacity.

The present patient underwent a combined anterior and posterior approach for surgery, with a low profile autologous iliac bone utilized to repair the bone defect. This approach is advantageous as it reduces the risk of secondary infection due to the limited use of internal fixation devices. Autologous iliac bone is also beneficial as it does not cause rejection reactions and can show high activity in a short period of time, helping to speed up vertebral fusion[22]. Additionally, the low profile autologous iliac bone has a strong cortical bone, which helps to maintain the intervertebral height in the early stage and prevent kyphosis. The morphology of bone defects after debridement is varied, and conventional implants may not be able to fit the bone defects completely; whereas autologous iliac bone is highly malleable and can be trimmed to fill the bone defects to the maximum extent. The plastic bone graft has a low profile shape, and its iliac wing curvature is similar to the anterior curvature of the cervical spine, which can help to avoid disruption of the anterior cervical organs. It can cover up to three sides of the bone cortex and its strength prevents it from sinking.

CONCLUSION

After anterior debridement for cervical spine infection, the reconstruction of bone defects using low-profile autologous iliac bone confers remarkable advantages with satisfactory short-term clinical outcomes, and can effectively resolve the difficulty of repairing and reconstructing bone defects following focal debridement for cervical infection. This surgical technique constitutes a reliable strategy for bone defect reconstruction after anterior debridement in cervical spine infection. However, as a single case report with a relatively short follow-up period, this study has certain limitations to note. Furthermore, prolonged follow-up and observation are warranted to confirm the long-term efficacy of the bone defect reconstruction and spinal stability.