Reduction and ring fixation of instable C1 fractures with monoaxial pedicle screws

Direct osteosynthesis in the treatment of atlas burst fractures: a systematic review

PURPOSE

The treatment of unstable atlas fractures remains a controversial topic. The study aims at assessing the prognosis and efficacy of osteosynthesis for unstable atlas fractures through a review of the current literature and additionally aims to compare outcomes between the transoral and posterior approaches.

METHODS

A systematic review of databases including PubMed, EMBASE, Cochrane, Web of Science, CNKI, and Wanfang was conducted. Titles and abstracts were screened by two reviewers to identify studies meeting pre-defined inclusion criteria for comprehensive analysis.

RESULTS

The systematic review included 28 articles, 19 employing the posterior approach and 9 utilizing the transoral approach. It covered osteosynthesis in 297 patients with unstable atlas fractures, comprising 169 treated via the posterior approach and 128 via the transoral approach. Analysis revealed high healing rates and clinical improvement in both approaches, evidenced by improvements in the visual analog scale, range of motion, atlantodens interval, and lateral displacement distance post-surgery.

CONCLUSION

Osteosynthesis offers effective treatment for unstable atlas fractures. Both transoral and posterior approaches can achieve good clinical outcomes for fracture, and biomechanical studies have confirmed that osteosynthesis can maintain the stability of the occipitocervical region, preserve the motor function of the atlantoaxial and occipito-atlantoaxial joints, and greatly improve the quality of life of patients. However, variations exist in the indications and surgical risks associated with each method, necessitating their selection based on a thorough clinical evaluation of the patient's condition.

Design of a novel lateral mass screw-plate system for the treatment of unstable atlas fractures: a finite element analysis

BACKGROUND

Osteosynthesis of unstable atlas fractures preserves joint motion and therefore has a distinct advantage over a range of treatment procedures. To prevent the potential disadvantages associated with osteosynthesis, a new atlas lateral mass screw-plate (LMSP) system has been designed. However, the biomechanical role of using the LMSP system in atlas internal fixation is not known. The aim of this study was to compare the biomechanical stability of a new LMSP with traditional posterior screw and rod (PSR) fixation techniques on the occipitocervical junction (C0-C2) through finite element analysis.

METHODS

A nonlinear C0-C2 finite element model of the intact upper cervical spine was developed and validated. The unstable model using the PSR system was then compared with the model using the LMSP system for fixation. A vertical load of 40 N was applied to the C0 to simulate head weight, while a torque of 1.5 Nm was applied to the C0 to simulate flexion, extension, lateral bending, and axial rotation.

RESULTS

The range of motion of both systems was close to the intact model. Compared with the LMSP system model, the PSR system model increased flexion, extension, lateral bending, and axial rotation by 4.9%, 3.0%, 5.0%, and 29.5% in the C0-C1 segments, and 4.9%, 2.7%, 2.4%, and 22.6% in the C1-C2, respectively. In flexion, extension, and lateral bending motion, the LMSP system model exhibited similar stress to the PSR system model, while in axial rotation, the PSR system model exhibited higher stress.

CONCLUSIONS

The findings of our study indicate that the two tested system models provide comparable stability. However, better stability was achieved during axial rotation with the LMSP system, and in this system, the maximum von Mises stress was less than that of the PSR one. As the atlantoaxial joint functions primarily as a rotational joint, the use of the LMSP system may provide a more stable environment for the joint that has become unstable due to fracture.

Posterior osteosynthesis with a new self-designed lateral mass screw-plate system for unstable atlas burst fractures

BACKGROUND

In the treatment of unstable atlas fractures using the combined anterior-posterior approach or the posterior monoaxial screw-rod system, factors such as severe trauma or complex surgical procedures still need to be improved despite the favourable reduction effect. This research described and evaluated a new technique for the treatment of unstable atlas fracture using a self-designed lateral mass screw-plate system.

METHODS

A total of 10 patients with unstable atlas fractures using this new screw-plate system from January 2019 to December 2021 were retrospectively reviewed. All patients underwent posterior open reduction and internal fixation (ORIF) with a self-designed screw-plate system. The medical records and radiographs before and after surgery were noted. Preoperative and postoperative CT scans were used to determine the type of fracture and evaluate the reduction of fracture.

RESULTS

All 10 patients were successfully operated with this new system, with an average follow-up of 16.7 ± 9.6 months. A total of 10 plates were placed, and all 20 screws were inserted into the atlas lateral masses. The mean operating time was 108.7 ± 20.1 min and the average estimated blood loss was 98.0 ± 41.3 ml. The lateral mass displacement (LMD) averaged 7.1 ± 1.9 mm before surgery and almost achieved satisfactory reduction after surgery. All the fractures achieved bony healing without reduction loss or implant failure. No complications (vertebral artery injury, neurologic deficit, or wound infection) occurred in these 10 patients. At the final follow-up, the anterior atlantodens interval (AADI) was 2.3 ± 0.8 mm and the visual analog scale (VAS) was 0.6 ± 0.7 on average. All patients preserved almost full range of motion of the upper cervical spine and achieved a good clinical outcome at the last follow-up.

CONCLUSIONS

Posterior osteosynthesis with this new screw-plate system can provide a new therapeutic strategy for unstable atlas fractures with simple and almost satisfactory reduction.

Unstable jefferson burst fractures (JBF): Intraoperative stability testing after posterior atlas ring osteosynthesis (C1-RO) allows determination of surgical procedure extent

Introduction

Motion preserving atlas ring osteosynthesis (C1-RO) for unstable Jefferson burst fractures (JBF) with insufficiency of the transverse atlantal ligament (TAL) is under debate. There is controversy about when to apply C1-RO and when further stabilization is needed.

Research question

Is intraoperative stability testing after C1-RO with restoration of secondary stabilizers feasible, and what are mid-to long-term results of posterior C1-RO vs. C1-C2 ORIF in unstable Jefferson burst fractures with Dickman type I or II transverse atlantal ligament lesions based on intraoperative decision using this stability testing?

Material and methods

Five consecutive patients with unstable JBF were treated with posterior C1-RO or C1-C2 ORIF based on the findings after intraoperative reduction and posterior C1-RO and stability testing. This newly developed intraoperative stability test based on the findings of biomechanical studies is a fluoroscopically controlled manual C1-C2 test with a force of approximately 50 ​N posterior-anterior stress and a tilting maneuver after C1-RO with repositioning. Clinical and radiological results of the cases with C1-RO were analyzed 3.5-21 months postoperatively.

Results

Posterior C1-RO was performed in four patients. One case required C1-C2 fixation due to significant instability. In cases of C1-RO, stable bony fusions of the atlas ring were observed within a year. In flexion-extension views, the anterior atlanto-dental interval (AADI) did not increase until the latest follow-up. No complications were observed.

Discussion and conclusion

The described intraoperative stability test after posterior C1-RO in unstable JBF enables the determination if C1-RO is sufficient or C1-C2 ORIF is necessary for treatment.

Motion-Preserving Navigated Primary Internal Fixation of Unstable C1 Fractures

Study Design

Prospective observational study.

Purpose

To assess the safety, efficacy, and benefits of computed tomography (CT)-guided C1 fracture fixation.

Overview of Literature

The surgical management of unstable C1 injuries by occipitocervical and atlantoaxial (AA) fusion compromises motion and function. Monosegmental C1 osteosynthesis negates these drawbacks and provides excellent functional outcomes.

Methods

The patients were positioned in a prone position, and cranial traction was applied using Mayfield tongs to restore the C0–C2 height and obtain a reduction in the displaced fracture fragments. An intraoperative, CT-based navigation system was used to enable the optimal placement of C1 screws. A transverse rod was then placed connecting the two screws, and controlled compression was applied across the fixation. The patients were prospectively evaluated in terms of their clinical, functional, and radiological outcomes, with a minimal follow-up of 2 years.

Results

A total of 10 screws were placed in five patients, with a mean follow-up of 40.8 months. The mean duration of surgery was 77±13.96 minutes, and the average blood loss was 84.4±8.04 mL. The mean combined lateral mass dislocation at presentation was 14.6±1.34 mm and following surgery, it was 5.2±1.64 mm, with a correction of 9.4±2.3 mm (p <0.001). The follow-up CT showed excellent placement of screws and sound healing. There were no complications and instances of AA instability. The clinical range of movement at 2 years in degrees was as follows: rotation to the right (73.6°±9.09°), rotation to the left (71.6°±5.59°), flexion (35.4°±4.5°), extension (43.8°±8.19°), and lateral bending on the right (28.4°±10.45°) and left (24.8°±11.77°). Significant improvement was observed in the functional Neck Disability Index from 78±4.4 to 1.6±1.6. All patients returned to their occupation within 3 months.

Conclusions

Successful C1 reduction and fixation allows a motion-preserving option in unstable atlas fractures. CT navigation permits accurate and adequate monosegmental fixation with excellent clinical and radiological outcomes, and all patients in this study returned to their preoperative functional status.

Comparison of radiological and clinical outcomes after surgical reduction with fixation or halo-vest immobilization for treating unstable atlas fractures

BACKGROUND

Unstable atlas fractures with concomitant transverse atlantal ligament (TAL) injury may be conservatively managed by halo-vest immobilization (HVI) or surgically treated by various fixation techniques. Many surgeons prefer surgical management due to complications, nonunion, and further dislocations with HVI. There are no comparative studies on surgical and nonsurgical management of unstable atlas fractures. We retrospectively assessed the radiological and clinical outcomes of surgical reduction with fixation vs. non-operative treatments for unstable atlas fractures with TAL rupture.

METHODS

We analyzed records of 24 patients (15 men, 9 women; mean age, 48.3 years) with at least 1 year of follow-up. They underwent HVI or surgical reduction with fixation for unstable atlas fracture combined with TAL injury. Clinical outcomes, including neck visual analog scale and neck disability index (NDI), and radiological measurements, including degree of fracture displacement, atlantodental interval (ADI), range of motion (ROM), cervical alignment, fusion rate, and time-to-fusion, were assessed.

RESULTS

Of the 24 patients, 13 were treated by surgical reduction with fixation (C1 lateral mass screw-C2 pedicle screw with a cross-link) and 11 by HVI. A significant reduction in lateral displacement of fractured lateral masses was identified in surgical reduction with fixation (3.21 ± 1.21 mm) compared with HVI (0.97 ± 2.69 mm). The mean reduction in ADI was 1.47 ± 1.08 mm with surgical fixation and 0.66 ± 1.02 mm with HVI. The bony rate and time-to-fusion were 100% and 14.91 ± 3.9 weeks with surgical reduction, and 72.7% and 22.31 ± 10.85 weeks with HVI. The postoperative neck pain relief and NDI after surgical fixation were higher than those after HVI.

CONCLUSIONS

Compared with HVI, surgical reduction with fixation reduces fractured lateral mass displacements, increases fusion rate, and reduces time-to-fusion while maintaining cervical curvature and improving neck pain and daily activities.