Posterior osteosynthesis of the atlas for nonconsolidated Jefferson fractures: a new surgical technique

Monoaxial Screws Versus Polyaxial Screws Osteosynthesis for Unstable Atlas Fractures: A Retrospective, Comparative Study With a Minimum Follow-Up of 3 years

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

The study aimed to compare the radiological parameters, clinical outcomes, and long-term effects of the posterior osteosynthesis with polyaxial screw-rod system and the monoaxial screw-rod system in the treatment of unstable atlas fractures.

METHODS

We retrospectively analyzed the clinical data of 33 patients with posterior ORIF for unstable atlas fractures in our hospital from August 2013 to June 2020, with a minimum of 3 years of follow-up. Polyaxial screws (group A) were used in 12 patients and monoaxial screws (group B) in 21 patients. Perioperative data, radiological parameters, and clinical outcomes were collected and compared between the 2 surgical approaches.

RESULTS

The operative time, blood loss, time of screw-rod system placement, and hospital stay were significantly lower in group A than in group B. At the last follow-up, the visual analog scale (VAS) score and anterior arch reduction rate of the atlas in group A were lower than those in group B, while the lateral mass displacement (LMD) in group A was higher than that in group B. There was no significant difference between Group A and Group B in terms of the anterior atlantodental interval (AADI), posterior arch reduction rate of the atlas, range of motion (ROM), and neck disability index (NDI).

CONCLUSIONS

Monoaxial screws can achieve better reduction results for unstable atlas fractures, especially for the anterior arch of atlas. However, the surgical operation of monoaxial screws is more complicated than that of polyaxial screws and has more complications. Appropriate implants should be selected for the treatment of unstable atlas fractures based on the type of atlas fracture, the experience of surgeons, and the demands of patients.

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 Temporary C1-2 Pedicle Screws Fixation for the Treatment of Unstable C1-2 Complex Fractures: Minimum of 2-Year Follow-Up

STUDY DESIGN

Retrospective.

OBJECTIVES

To present rarely reported complex fractures of the upper cervical spine (C1-C2) and discuss the clinical results of the posterior temporary C1-2 pedicle screws fixation for C1-C2 stabilization.

METHODS

A total of 19 patients were included in the study (18 males and 1 female). Their age ranged from 23 to 66 years (mean age of 39.6 years). The patients were diagnosed with complex fractures of the atlas and the axis of the upper cervical spine and underwent posterior temporary C1-2 pedicle screws fixation. The patients underwent a serial postoperative clinical examination at approximately 3, 6, 9 months, and annually thereafter. The neck disability index (NDI) and the range of neck rotary motion were used to evaluate the postoperative clinical efficacy of the patients.

RESULTS

The average operation time and blood loss were 110 ± 25 min and 50 ± 12 ml, respectively. The mean follow-up was 38 ± 11 months (range 22 to 60 months). The neck rotary motion before removal, immediately after removal, and the last follow-up were 68.7 ± 7.1°, 115.1 ± 11.7°, and 149.3 ± 8.9° (P < 0.01). The NDI scores before and after the operation were 42.7 ± 4.3, 11.1 ± 4.0 (P < 0.01), and the NDI score 2 days after the internal fixation was removed was 7.3 ± 2.9, which was better than immediately after the operation (P < 0.01), and 2 years after the internal fixation was removed. The NDI score was 2.0 ± 0.8, which was significantly better than 2 days after the internal fixation was taken out (P < 0.001).

CONCLUSIONS

Posterior temporary screw fixation is a good alternative surgical treatment for unstable C1-C2 complex fractures.

Transoral unilateral lag screw osteosynthesis for coronal split fracture of the lateral mass of the atlas - case report, operative technique and review of the literature

Introduction

Atlas ring fractures, which account for 1.3% of all spinal fractures, are predominantly managed conservatively. However, in certain cases, surgical treatment may be necessary depending on the type of fracture, degree of comminution, fracture location, and associated ligamentous injuries. Surgical stabilization frequently results in a posterior C1-2 or C0-2 fusion, which restricts movement, particularly craniocervical rotation. Coronal split fractures of the lateral mass need to be reduced and fixed due to dislocation, instability and secondary osteoarthritis. The preferred treatment approach involves internal fixation of the reduced fracture fragments, while avoiding restriction of the upper cervical spine's range of motion (ROM).

Research question

Is unilateral anterior transoral lag screw for treatment of unstable coronal split fracture of lateral mass of the atlas feasible and a safe treatment option?

Case Report Material and Methods

We report on a 55-year-old female suffering from polytrauma with multiple spinal and extremity injuries.

Results

A coronal split fracture of the lateral mass of the atlas was treated minimally invasive with a transoral lag screw technique to reduce and fix the fracture that has a tendency for fracture gap widening. Stable fixation and fracture union and thus restoration of function was achieved.

Discussion and conclusion

Transoral lag screw osteosynthesis for coronal split fracture of the lateral mass of the atlas is a potential treatment option in selected cases to preserve mobility in the upper cervical spine after spinal trauma.

Treatment of unstable C1 semi-ring fractures with direct C1 pedicle screw fixation using a navigational template: A case report and literature review

RATIONALE

Because of the risk of C1 to C2 instability, which would reduce the mobility of the occipito-atlanto-axis articulation, unstable C1 semi-ring fractures are typically treated with C1 to C2 or C0 to C2 fusion. The vertebral artery and spinal cord are at risk of harm during the installation of C1 pedicle screws. There is a need for a method that can maintain the occipito-atlanto-axis articulation's mobility and increase the safety of C1 pedicle screw fixation, particularly for surgeons who have less experience inserting C1 pedicle screws freehand.

PATIENT CONCERNS

A 45-year-old man who had suffered a severe fall from a height of 2.5 m presented with pain in his cervical spine. Magnetic resonance imaging and computed tomography were used to diagnose unstable atlas fractures.

DIAGNOSIS

According to radiographic studies, the patient had a unilateral anterior and posterior arch fracture (semi-ring fracture, Landells type II), as well as fractures and transverse ligament avulsion at the attachment site.

INTERVENTIONS

We fixed the C1 directly with a pedicle screw using a navigational template.

OUTCOMES

Both during and after the operation, there were no connected complications. Imaging at 12 months after surgery demonstrated that the fracture had united. The average visual analog scale score decreased from 8 before surgery to 2.

LESSONS

In particular for surgeons with less experience placing freehand C1 pedicle screws, direct C1 pedicle screw fixation with the aid of a navigational template was a good option because it can preserve the mobility of the occipito-atlanto-axis articulation and improve the safety of C1 pedicle screw.

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.

C1-ring osteosynthesis versus C1-2 fixation fusion in the treatment of unstable atlas fractures: a multicenter, prospective, randomized controlled study with 5-year follow-up

OBJECTIVE

The aim of the present study was to compare the long-term effects of posterior C1-ring osteosynthesis and C1-2 fixation fusion in the treatment of unstable atlas fractures.

METHODS

A multicenter, prospective, randomized controlled trial was conducted to analyze 73 patients with atlas fractures who underwent posterior fixation. The intervention group was treated with C1-ring osteosynthesis, and the control group was treated with C1-2 fixation fusion. The patients were followed up for 6 months, 1 year, 2 years, and 5 years after the operation.

RESULTS

Fifty-two patients had complete data at the last follow-up. The visual analog scale (VAS) score for neck pain in the intervention group was lower than that in the control group (p < 0.001). The operation time, intraoperative blood loss, radiation dose, bedridden period, hospital stay, and cost in the intervention group were significantly lower than those in the control group (p < 0.001). At the last follow-up, the Neck Disability Index in the intervention group was higher than that of the control group, and the angle of flexion-extension and axial rotation in the intervention group were greater than those in the control group (p < 0.001).

CONCLUSIONS

In this study, the authors found that posterior C1-ring osteosynthesis is superior to C1-2 fixation fusion in terms of long-term relief of neck pain and preservation of the physiological function of the cervical vertebrae. This technique is a reliable choice for the treatment of unstable C1 fractures.

Direct Internal Fixation for Unstable Atlas Fractures

PURPOSE

To investigate the radiologic and clinical outcomes of direct internal fixation for unstable atlas fractures.

MATERIALS AND METHODS

This retrospective study included 12 patients with unstable atlas fractures surgically treated using C1 lateral mass screws, rods, and transverse connector constructs. Nine lateral mass fractures with transverse atlantal ligament (TAL) avulsion injury and three 4-part fractures with TAL injury (two avulsion injuries, one TAL substance tear) were treated. Radiologic outcomes included the anterior atlantodental interval (AADI) in flexion and extension cervical spine lateral radiographs at 6 months and 1 year after treatment. CT was also performed to visualize bony healing of the atlas at 6 months and 1 year. Visual Analog Scale (VAS) scores for neck pain, Neck Disability Index (NDI) values, and cervical range of motion (flexion, extension, and rotation) were recorded at 6 months after surgery.

RESULTS

The mean postoperative extension and flexion AADIs were 3.79±1.56 (mean±SD) and 3.13±1.01 mm, respectively. Then mean AADI was 3.42±1.34 and 3.33±1.24 mm at 6 months and 1 year after surgery, respectively. At 1 year after surgery, 11 patients showed bony healing of the atlas on CT images. Only one patient underwent revision surgery 8 months after primary surgery due to nonunion and instability findings. The mean VAS score for neck pain was 0.92±0.99, and the mean NDI value was 8.08±5.70.

CONCLUSION

C1 motion-preserving direct internal fixation technique results in good reduction and stabilization of unstable atlas fractures. This technique allows for the preservation of craniocervical and atlantoaxial motion.

Posterior Osteotomy and Osteosynthesis for Malunited Atlas Fracture: A Surgical Technique

Conservative treatment is commonly accepted and widely used for most atlas compression fractures. Malunion due to mismatching of the articular surfaces in C0-C1 and C1-C2 is therefore frequent even without associated instability. Such a result is considered acceptable in the elderly with low functional requests but should be avoided in young patients. Authors describe a new surgical technique to reduce and fix a nonunion and malunited fracture of the atlas through a posterior arch osteotomy followed by articular masses stabilization with polyaxial screws and precurved titanium rod. Rod prebending reduces lateral inclination of the screw heads during the reduction maneuver through compression applied between screw heads making it effective.

C1 and C2 Fractures Above a Previous Fusion Treated with Internal Fixation without Fusion: A Case Report

CASE

A 71-year-old woman sustained C1 lateral mass and type 2 odontoid fractures 3 years after C2-T2 anterior-posterior fusion. She was treated with C1-C4 instrumentation without fusion for 9 months followed by instrumentation removal to restore atlantoaxial motion. After instrumentation removal, she maintained clinically relevant cervical lateral bending, rotation, and flexion and extension.

CONCLUSION

The loss of upper cervical motion after C1-C2 instrumented fusion may be debilitating for patients in the setting of previous subaxial cervical fusion. Temporary instrumentation without fusion may allow for preservation of upper cervical motion in patients with concomitant C1 and C2 fractures above a previous cervical fusion.

[Progress in treatment of unstable atlas fracture]

OBJECTIVE

To summarize the progress in treatment of unstable atlas fracture, the existing problems, and the research direction.

METHODS

Related literature at home and abroad was reviewed. The stability evaluation of atlas fracture and treatment methods were introduced, and the selection of surgical approach and fixation instruments in treatment of unstable atlas fracture were summarized and analyzed.

RESULTS

At present, atlas fractures are considered as unstable fractures except single anterior arch fractures with complete transverse ligament or simple posterior arch fractures. The treatment of unstable atlas fracture has been developed from nonsurgical treatment and traditional fusion surgery to single-segment fixation. Nonsurgical treatment is less effective, while traditional fusion surgery has a disadvantage of limited the motion of the upper cervical spine. Single-segment fixation can not only restore and fix the fracture, but also preserve the upper cervical motion function. Single-segment fixation approaches include posterior and transoral approaches, and the fixation instruments are being constantly improved, mainly including screw-rod system, screw-plate system, and plate system.

CONCLUSION

For unstable atlas fracture, single-segment fixation is an ideal surgical method, and has more advantages when compared with nonsurgical treatment and traditional fusion surgery. Single-segment fixation via transoral approach is more direct for atlas anterior arch fracture reduction, but there is a high risk of infection; and single-segment fixation via posterior approach is less effective for the reduction of atlas anterior arch fracture. Therefore, a better reduction method should be explored.

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.

Atlas Fractures: Diagnosis, Current Treatment Recommendations, and Implications for Elderly Patients

Fractures of the C1 vertebrae (atlas) are commonly the result of falls and other trauma, which cause hyperextension, or axial compression of the cervical spine. Although historically thought as a benign injury with lower neurological risks, current data suggests that this may not hold true for geriatric patients (aged 65 y and older) who may be predisposed to these fractures even after lower-energy trauma such as ground-level falls. Advancements in orthopedic trauma care has increased our diagnostic abilities to identify and manage patients with C1 fractures and other upper cervical spine trauma. However, there are no universal treatment guidelines based on level I trials. Current treatment ranges from nonoperative to operative management depending on fracture-pattern and integrity of the surrounding ligaments. Furthermore, in the elderly patients these fractures present a unique dilemma due to preexisting comorbidities and contraindications to various treatment modalities. C1 fractures warrant greater recognition to provide optimal treatment to patients and minimize the risk for developing complications. The goal of this review is to highlight the most updated treatment guidelines and to discuss the complications of both operative and nonoperative management of C1 fractures especially among the elderly patient population.

Transoral screw and wire fixation for unstable anterior ½ atlas fracture

Study Design:

Atlas fractures are evaluated according to the fracture type and ligamentous injury. External immobilization may result in fracture nonunion.

Objective:

The ideal treatment method for non-stabilized atlas fractures is limited fixation without restricting the range of motion of the atlantoaxial and atlantooccipital joints.

Summary of Background Data:

Such a result can be established by using either anterior fixation or posterior lateral mass fixation. However, none of these techniques can fully address anterior 1/2 atlas fractures such as in this case.

Materials and Methods:

A transoral technique in which bilateral screws were placed intralaminarly and connected with wire was used to reduce and stabilize an anterior 1/2 fracture of C1.

Result:

Radiological studies after the surgery showed good cervical alignment, no screw or wire failure and good reduction with fusion of anterior arcus of C1.

Conclusions:

Internal immobilization by this screw and wire osteosynthesis technique protects the mobility of the atlanto-occipital and atlantoaxial joints. The main advantage is that neither the twisted wires inserted under the anterior lamina, nor the laterally placed screw heads interfere with midline wound closure; unlike the plate/cage and rod systems used together with anterior screws. A computer navigation system with intraoperative 3D imaging facilities will be of benefit for safe placement of the screw, however we preferred a free-hand technique, as the starting point was at the fracture line along the trajectory of the routinely accessible anterior lamina.

Posterior osteosynthesis with monoaxial lateral mass screw-rod system for unstable C1 burst fractures

BACKGROUND CONTEXT

Surgical treatment for unstable atlas fractures has evolved in recent decades from C1-C2 or C0-C2 fusion to motion-preservation techniques of open reduction and internal fixation (ORIF). However, regardless of a transoral or a posterior approach, the reduction is still not satisfactory.

PURPOSE

The article describes and evaluates a new technique for treating unstable atlas fractures by using a monoaxial screw-rod system.

STUDY DESIGN

This is a retrospective study.

PATIENT SAMPLE

The sample includes adult patients with unstable C1 fractures treated with a posterior monoaxial screw-rod system.

OUTCOME MEASURES

The outcome measures included a visual analog pain scale, radiographic reduction (lateral mass displacement [LMD]), maintenance of reduction, C1-C2 instability (anterior atlantodens interval), and complications.

MATERIALS AND METHODS

From August 2013 to May 2016, nine consecutive patients with unstable atlas fractures were retrospectively reviewed. All patients were treated with posterior ORIF by using a monoaxial screw-rod system. The medical records and the preoperative and postoperative radiographs were reviewed. Preoperative and postoperative computed tomography scans were used to specify the fracture types and to assess the reduction.

RESULTS

All nine patients with a mean age of 50.3 years successfully underwent surgery with this technique, and a follow-up of 17.4±9.3 months was performed. Transverse atlantal ligament (TAL) injury was found in eight of the nine patients: one of type I and seven of type II. The preoperative LMD averaged 7.0±2.2 mm and was restored completely after surgery; all the fractures achieved bony healing without loss of reduction or implant failure. None of the patients had complications of neurologic deficit, vertebral artery injury, or wound infection associated with the surgical procedure. Two patients complained of greater occipital nerve neuralgia after the operation, which gradually disappeared in 1 month. All patients had a well-preserved range of motion of the upper cervical spine at the final follow-up.

CONCLUSIONS

Posterior osteosynthesis with a monoaxial screw-rod system is capable of an almost anatomical reduction for the unstable atlas fractures. The TAL incompetence may not be a contraindication to ORIF for C1 fractures, but the long-term effect of C1-C2 instability remains to be further investigated.

Management of Isolated Atlas Fractures: A Retrospective Study of 65 Patients

BACKGROUND

Jefferson fractures, or burst fractures of the C1 vertebra, can be managed surgically or conservatively, depending on their stability.

METHODS

We identified all patients who were treated for a C1 fracture at our institution between 1999 and 2016 for retrospective analysis. Patients with any other concurrent cervical fractures or nontraumatic etiology of fracture were excluded. Stability was defined as either lateral mass displacement ≥7 mm on computed tomography or presence of transverse atlantal ligament disruption on magnetic resonance imaging. We collected data on patients' demographic, clinical, and radiographic presentation and identified variables independently associated with instability at presentation and failure to achieve fusion at follow-up.

RESULTS

We identified 65 patients. On multivariable regression, instability at presentation was independently associated with atlantodens interval (odds ratio [OR] 2.357, 95% confidence interval [CI] [0.0629-1.271], P = 0.099) and type 3 fracture (OR 6.081, 95% CI [1.068-34.612], P = 0.042). Failure to achieve fusion was independently associated with age (OR 1.226, 95% CI [1.007-1.495], P = 0.043), motor vehicle collision as mechanism of injury (OR 22834.3, 95% CI [3.135-1.66e8], P = 0.027), and type 2 fracture (OR 168.537, 95% CI [1.743-16292.92], P = 0.028). Type 3 fracture was positively associated with halo vest for management (OR 17.171, 95% CI [2.882-102.289], P = 0.002) and negatively associated with a rigid cervical collar for management (OR 0.0616, 95% CI [0.0104-0.3653], P = 0.002). All 4 patients who underwent surgery presented with unstable fracture (P = 0.0187).

CONCLUSIONS

Atlantodens interval, mechanism of injury, and fracture type affect Jefferson fracture management decisions and outcomes, including instability at presentation and fusion at follow-up. Most fractures were managed nonsurgically regardless of stability.

Atlas Fractures and Atlas Osteosynthesis: A Comprehensive Narrative Review

Most atlas fractures are the result of compression forces. They are often combined with fractures of the axis and especially with the odontoid process. Multiple classification systems for atlas fractures have been described. For an adequate diagnosis, a computed tomography is mandatory. To distinguish between stable and unstable atlas injury, it is necessary to evaluate the integrity of the transverse atlantal ligament (TAL) by magnetic resonance imaging and to classify the TAL lesion. Studies comparing conservative and operative management of unstable atlas fractures are unfortunately not available in the literature; neither are studies comparing different operative treatment strategies. Hence all treatment recommendations are based on low level evidence. Most of atlas fractures are stable and will be successfully managed by immobilization in a soft/hard collar. Unstable atlas fractures may be treated conservatively by halo-fixation, but nowadays more and more surgeons prefer surgery because of the potential discomfort and complications of halo-traction. Atlas fractures with a midsubstance ligamentous disruption of TAL or severe bony ligamentous avulsion can be treated by a C1/2 fusion. Unstable atlas fractures with moderate bony ligamentous avulsion may be treated by atlas osteosynthesis. Although the evidence for the different treatment strategies of atlas fractures is low, atlas osteosynthesis has the potential to change treatment philosophies. The reasons for this are described in this review.

Computer-aided analysis for optimal screw insertion in lateral mass of C1: An anatomical study

INTRODUCTION

Motion preserving techniques in C1 ring fractures are increasingly used especially in young patients. Therefore, lateral mass screws are inserted in the first vertebra and connected by a rod. The purpose of this study was to determine safe zones regarding the vertebral arteries and the medulla oblongata for optimal lateral mass screw positioning when fusing the C1-ring.

MATERIALS AND METHODS

Images of the cervical spine of 50 patients (64-line CT scanner) were evaluated and virtual screws were positioned in both lateral masses of the first vertebra using 3D-reconstructions of CT scans. The length of the screws, the insertion angles in two planes, the distance to the vertebral artery, and the spinal canal was investigated. Descriptive statistics was used and gender-dependent differences were calculated using student t-test. A diameter of 4 mm was chosen for the screws.

RESULTS

The mean screw length was 30.0 ± 2.3 mm on the right and 30.1 ± 2.1 mm on the left side. The arithmetic mean for the transverse angle was 16.4 ± 5.6° on the right and 15.6 ± 6.3° on the left, the sagittal angle averaged 8.3 ± 3.8° on the right, and 11.0 ± 4.9° on the left side. The mean distance between screw and spinal canal has been determined on the right with 2.4 ± 0.7 mm and 2.2 ± 0.6 mm on the left side. The distance from the C1 lateral mass screw to the vertebral artery was on average 7.1 ± 1.5 mm on the right side (significant correlation with gender, p value: 0.03) and 7.4 ± 1.4 mm on the left side.

CONCLUSIONS

Screws should be positioned with a slightly converging angle of 16° and a slightly ascending angle of 10°. Due to the required high precision technique intraoperatively multiplanar 2 D or 3 D imaging is recommended to avoid harm to the vertebral artery or the spinal canal.

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

INTRODUCTION

Ring fixation of C1 can be performed using pedicle screws and a rod in case of unstable Jefferson or lateral mass fractures of C1.

MATERIALS AND METHODS

In a case series of three patients, we stabilized C1 fractures surgically using a modified technique of C1 ring fixation by using monoaxial instead of polyaxial screws. Functional outcome and pain was recorded postoperatively.

RESULTS

In this very small case series, we observed good results concerning pain and functional outcome. All fractures were bony healed within 13 weeks. In one case, a screw penetrated the spinal canal and had to be repositioned. A mild irritation of C2 nerve root occurred in two cases postoperatively.

CONCLUSION

C1 Ring fusion with monoaxial screws provides a good ability to reduce the fracture indirectly by the screws and the rod itself.

Solitary C1 Posterior Fixation for Unstable Isolated Atlas Fractures: Case Report and Systematic Review of the Literature

Study Design A systematic review of the literature. Objectives To review the published results to date of motion-preserving direct reconstruction of C1 ring fractures with combined coronal plane displacement of at least 7 mm (rule of Spence) and so at risk for Dickman type I or II disruption of the transverse atlantal ligament (TAL). Methods A structured literature review prompted by successful management of a typical case. Results To date only 65 such cases are reported and follow-up is almost uniformly short. Although reported clinical success is uniform, the case mix is heterogenous and confirmation/classification of ligamentous injury at baseline is often lacking. Conclusions Direct C1 stabilization shows promise as a "more selective" option in managing displaced atlas fractures with probable TAL disruption but cannot yet be recommended as a practice standard. Prospective clinical studies are indicated and should be structured so as to differentiate between Dickman type I and type II injuries of the TAL.

Unilateral lag-screw technique for an isolated anterior 1/4 atlas fracture

STUDY DESIGN

Fractures of the atlas are classified based on the fracture location and associated ligamentous injury. Among patients with atlas fractures treated using external immobilization, nonunion of the fracture could be seen.

OBJECTIVE

Ideally, treatment strategy for an unstable atlas fracture would involve limited fixation to maintain the fracture fragments in a reduced position without restricting the range of motion (ROM) of the atlantoaxial and atlantooccipital joints.

SUMMARY OF BACKGROUND DATA

Such a result can be established using either transoral limited internal fixation or limited posterior lateral mass fixation. However, due to high infection risk and technical difficulty, posterior approaches are preferred but none of these techniques can fully address anterior 1/4 atlas fractures such as in this case.

MATERIALS AND METHODS

A novel open and direct technique in which a unilateral lag screw was placed to reduce and stabilize a progressively widening isolated right-sided anterior 1/4 single fracture of C1 that was initially treated with a rigid cervical collar is described.

RESULTS

Radiological studies made after the surgery showed no implant failure, good cervical alignment, and good reduction with fusion of C1.

CONCLUSIONS

It is suggested that isolated C1 fractures can be surgically reduced and immobilized using a lateral compression screw to allow union and maintain both C1-0 and C1-2 motions, and in our knowledge this is the first description of the use of a lag screw to achieve reduction of distracted anterior 1/4 fracture fragments of the C1 from a posterior approach. This technique has the potential to become a valuable adjunct to the surgeon's armamentarium, in our opinion, only for fractures with distracted or comminuted fragments whose alignment would not be expected to significantly change with classical lateral mass screw reduction.

A retrospective review of fixation of C1 ring fractures--does the transverse atlantal ligament (TAL) really matter?

BACKGROUND CONTEXT

In contrast to the majority of outcome data, many consider C1 fractures to be benign injuries and so have advocated for conservative management, except in the case of concomitant transverse atlantal ligament (TAL) injury where C1-C2 or occiput-C2 fusions are recommended.

PURPOSE

Our goal was to evaluate a series of unstable C1 fractures treated with C1 open reduction and internal fixation (ORIF) to assess clinical and radiographic outcomes by determining the success of reduction and pain relief.

STUDY DESIGN/SETTING

This is a retrospective cohort review.

PATIENT SAMPLE

The sample includes adult patients with unstable C1 fractures treated with open reduction and primary internal fixation.

OUTCOME MEASURES

Primary outcome measures included visual analog pain scale (VAS), radiographic reduction (lateral mass displacement), maintenance of reduction, C1-C2 instability, and complications.

METHODS

A retrospective review of all patients with C1 fractures between September 2002 and September 2013 identified 12 consecutive patients from a level I trauma center who were treated with primary internal fixation without fusion. Electronic medical records and preoperative and postoperative radiographs were reviewed. The surgical technique consisted of a posterior cervical approach to the C1 arch and open reduction using bilateral C1 lateral mass screws connected transversely with a rod. Pre- and postoperative computed tomography scans were used to assess reduction. Long-term follow-up flexion and extension radiographs were used to assess C1-C2 stability. The authors did not receive relevant funding in relation to this research.

RESULTS

Twelve patients underwent C1 ORIF, with a mean age of 43 (9 males and 3 females) and a mean follow-up of 17 months. Transverse atlantal ligament was found to be disrupted with type I or type II injury in 11 of the 12 patients: 5 type I and 6 type II. Preoperative lateral mass displacement averaged 7.1 mm, with postoperative displacement after reduction averaging 2.4 mm (p-value <.001). The VAS score averaged 0.7 at latest follow-up. No patients went on to develop C1-C2 instability on final flexion-extension films. No patients had a complication that resulted in neurologic deficit or vascular injury associated with the procedure. No patients were found to have late sequelae of malunion or loss of reduction. Two surgically related complications occurred, namely one patient with errant screw requiring return to the operating room (OR) and one with arthrosis of the occipital-C1 joint.

CONCLUSIONS

Although a small series, early evidence suggests that patients with unstable C1 ring fractures can be successfully managed with primary ORIF. Open reduction and internal fixation results in a stable construct that maintains reduction, results in excellent pain control, and does not lead to C1-C2 instability. In our series, we have not observed the presence of TAL injury to adversely affect outcomes, and thus do not believe it is a contraindication to ORIF. Comparative studies comparing internal fixation with non-operative, C1-C2, or occiput-C2 fusions would yield more insight into optimal treatment options for these fractures.

Posterior osteosynthesis of a spontaneous bilateral pedicle fracture of the lumbar spine

Spontaneous bilateral pedicle fractures of the lumbar spine are rare, and an optimal surgical treatment has not been suggested. The authors report the case of a 50-year-old woman who presented with low-back pain and right leg radiating pain of 1 year's duration. Radiological studies revealed a spontaneous bilateral pedicle fracture of L-5. All efforts at conservative treatment failed, and the patient underwent surgery for osteosynthesis of the fractured pedicle using bilateral pedicle screws connected with a bent rod. Her low-back and right leg pain were relieved postoperatively. A CT scan performed 3 months postoperatively revealed the disappearance of the pedicle fracture gap and presence of newly formed bony trabeculation. In rare cases of spontaneous bilateral pedicle fracture of the lumbar spine, osteosynthesis of the fractured pedicle using bilateral pedicle screws and a bent rod is a motion-preserving technique that may be an effective option when conservative management has failed.

The effect of C1 bursting fracture on comparative anatomical relationship between the internal carotid artery and the atlas

PURPOSE

To describe the effect of the C1 bursting fracture on the location of the internal carotid artery (ICA) around the atlas.

METHODS

The authors analyzed the morphology of the atlas and the ICA in 15 patients with C1 bursting fracture and compared with control group (77 patients) without any pathology. All patients were evaluated with CT angiography for the anatomical assessment. The laterality of the ICA, the distances of the ICA from the midline, anterior tubercle, and ventral surface of the C1 lateral mass were compared between two groups. The distance between the lateral margin of the longus capitis muscle and the inner edge of the transverse foramen was also measured.

RESULTS

Medially located ICA was more common in the C1 bursting fracture group than control group (76.7 vs 42.8 %). There were no significant differences between 2 groups for the distance from the midline, anterior tubercle, and ventral surface of the C1 lateral mass, respectively. The distance of the longus capitis muscle to transverse foramen was 2.52 ± 2.09 and 4.15 ± 3.09 mm in each group, and there was statistically significant difference (p < 0.01).

CONCLUSIONS

Lateral displacement of the bony structure of C1 bursting fracture changes the relative location of the ICA medially, which increase the injury risk during the bicortical C1 screw insertion. These data suggest that CT angiography or enhanced CT scans can give critical information to choose the ideal fixation technique and the proper trajectory of the screws for C1 bursting fracture.

Self-designed posterior atlas polyaxial lateral mass screw-plate fixation for unstable atlas fracture

BACKGROUND CONTEXT

Most atlas fractures can be effectively treated nonoperatively with external immobilization unless there is an injury to the transverse atlantal ligament. Surgical stabilization is most commonly achieved using a posterior approach with fixation of C1-C2 or C0-C2, but these treatments usually result in loss of the normal motion of the C1-C2 and C0-C1 joints.

PURPOSE

To clinically validate feasibility, safety, and value of open reduction and fixation using an atlas polyaxial lateral mass screw-plate construct in unstable atlas fractures.

STUDY DESIGN

Retrospective review of patients who sustained unstable atlas fractures treated with polyaxial lateral mass screw-plate construct.

PATIENT SAMPLE

Twenty-two patients with unstable atlas fractures who underwent posterior atlas polyaxial lateral mass screw-plate fixation were analyzed.

OUTCOME MEASURES

Visual analog scale, neurologic status, and radiographs for fusion.

METHODS

From January 2011 to September 2012, 22 patients with unstable atlas fractures were treated with this technique. Patients' charts and radiographs were reviewed. Bone fusion, internal fixation placement, and integrity of spinal cord and vertebral arteries were assessed via intraoperative and follow-up imaging. Neurologic function, range of motion, and pain levels were assessed clinically on follow-up.

RESULTS

All patients were followed up from 12 to 32 months, with an average of 22.5±18.0 months. A total of 22 plates were placed, and all 44 screws were inserted into the atlas lateral masses. The mean duration of the procedure was 86 minutes, and the average estimated blood loss was 120 mL. Computed tomography scans 9 months after surgery confirmed that fusion was achieved in all cases. There was no screw or plate loosening or breakage in any patient. All patients had well-preserved range of motion. No vascular or neurologic complication was noted, and all patients had a good clinical outcome.

CONCLUSIONS

An open reduction and posterior internal fixation with atlas polyaxial lateral mass screw-plate is a safe and effective surgical option in the treatment of unstable atlas fractures. This technique can provide immediate reduction and preserve C1-C2 motion.

Unstable Jefferson fractures: Results of transoral osteosynthesis

BACKGROUND

Majority of C1 fractures can be effectively treated conservatively by immobilization or traction unless there is an injury to the transverse ligament. Conservative treatment usually involves a long period of immobilization in a halo-vest. Surgical intervention generally involves fusion, eliminating the motion of the upper cervical spine. We describe the treatment of unstable Jefferson fractures designed to avoid these problems of both conservative and invasive methods.

MATERIALS AND METHODS

A retrospective review of 12 patients with unstable Jefferson fractures treated with transoral osteosynthesis of C1 between July 2008 and December 2011 was performed. A steel plate and C1 lateral mass screw fixation were used to repair the unstable Jefferson fractures. Our study group included eight males and four females with an average age of 33 years (range 23-62 years).

RESULTS

Patients were followed up for an average of 16 months after surgery. Range of motion of the cervical spine was by and large physiologic: Average flexion 35° (range 28-40°), average extension 42° (range 30-48°). Lateral bending to the right and left averaged 30° and 28° respectively (range 12-36° and 14-32° respectively). The average postoperative rotation of the atlantoaxial joint, evaluated by functional computed tomography scan was 60° (range 35-72°). Total average lateral displacement of the lateral masses was 7.0 mm before surgery (range 5-12 mm), which improved to 3.5 mm after surgery (range 1-6.5 mm). The total average difference of the atlanto-dens interval in flexion and extension after surgery was 1.0 mm (range 1-3 mm).

CONCLUSIONS

Transoral osteosynthesis of the anterior ring using C1 lateral mass screws is a viable option for treating unstable Jefferson fractures, which allows maintenance of rotation at the C1-C2 joint and restoration of congruency of the atlanto-occipital and atlantoaxial joints.

Unstable atlas fracture treatment by anterior plate C1-ring osteosynthesis using a transoral approach

STUDY DESIGN

A retrospective study was conducted to evaluate anterior plate fixation of unstable atlas fractures using a transoral approach.

OBJECTIVE

To further investigate the safety and efficacy of this surgical technique, as there is currently a paucity of available data. While most atlas fractures can be managed by external immobilization with favorable results, surgery is usually preferable in highly unstable cases. Surgical stabilization is most commonly achieved using a posterior approach with fixation of C1-C2 or C0-C2, but these techniques usually result in loss of joint function and cannot fully stabilize anterior arch fractures of the atlas. Although a transoral approach circumvents these issues, only nine cases were described in the literature to our knowledge.

METHODS

Twenty patients with unstable atlas fractures were treated with this technique during a 6-year period. Screw and plate placement, bone fusion, and integrity of spinal cord and vertebral arteries were assessed via intraoperative and follow-up imaging. Neurologic function, range of motion, strength, pain levels, and signs of infection were assessed clinically upon follow-up.

RESULTS

There were no incidents of screw loosening or breakage, plate displacement, spinal cord injury, or vertebral artery injury. A total of 20 plates were placed and all 40 screws were inserted into the atlas lateral masses. CT scans demonstrated that two screws were placed too close to the vertebral artery canal, but without clinical consequences. Imaging demonstrated that bone fusion was achieved in all cases by 6 months postoperatively, without intervertebral instability. No plate-related complications were observed in any patients during the follow-up period.

CONCLUSIONS

C1 anterior plate fixation using a transoral approach appears to be a safe, reliable, and function-preserving surgical method for the management of unstable atlas fractures. For this type of fracture, a transoral approach with anterior fixation should be considered as an alternative to posterior approaches or conservative treatments.