Distractive flexion injuries of the subaxial cervical spine treated with anterior plate alone

Evolution of Patient-Reported Outcome Measures, 1, 2, and 5 years after Surgery for Subaxial Cervical Spine Fractures, A Nation-Wide Registry Study

BACKGROUND CONTEXT

A longer duration of patient follow-up arguably provides more reliable data on the long-term effects of a treatment. However, the collection of long-term follow-up data is resource demanding and often complicated by missing data and patients being lost to follow-up. In surgical fixation for cervical spine fractures, data are lacking on the evolution of patient reported outcome measures (PROMs) beyond 1-year of follow-up. We hypothesized that the PROMs would remain stable beyond the 1-year postoperative follow-up mark, regardless of the surgical approach.

PURPOSE

To assess the trends in the evolution of patient-reported outcome measures (PROMs) at 1, 2-, and 5-years following surgery in patients with traumatic cervical spine injuries.

STUDY DESIGN

Nation-wide observational study on prospectively collected data.

PATIENT SAMPLE

Individuals treated for subaxial cervical spine fractures with anterior, posterior, or combined anteroposterior approaches, between 2006 and 2016 were identified in the Swedish Spine Registry (Swespine).

OUTCOME MEASURES

PROMs consisting of EQ-5D-3L_index and the Neck Disability Index (NDI) were considered.

METHODS

PROMs data were available for 292 patients at 1 and 2 years postoperatively. Five-years PROMs data were available for 142 of these patients. A simultaneous within-group (longitudinal) and between group (approach-dependent) analysis was performed using mixed ANOVA. The predictive ability of 1-year PROMs was subsequently assessed using linear regression.

RESULTS

Mixed ANOVA revealed that PROMs remained stable from 1- to 2-years as well as from 2- to 5-years postoperatively and were not affected by the surgical approach (p<0.05). A strong correlation was found between 1-year and both 2- and 5-years PROMs (R>0.7; p<0.001). Linear regression confirmed the accuracy of 1-year PROMs in predicting both 2- and 5-years PROMs (p<0.001).

CONCLUSION

PROMs remained stable beyond 1-year of follow-up in patients treated with anterior, posterior, or combined anteroposterior surgeries for subaxial cervical spine fractures. The 1-year PROMs were strong predictors of PROMs measured at 2, and 5 years. The 1-year PROMs were sufficient to assess the outcomes of subaxial cervical fixation irrespective of the surgical approach.

Reduction of Lower Cervical Facet Dislocation: A Review of All Techniques

Objective: The surgical treatment of lower cervical facet dislocation is controversial. Great advancements on reduction techniques for lower cervical facet dislocation have been made in the past decades. However, there is no article reviewing all the reduction techniques yet. The aim is to review the evolution and advancements of the reduction techniques for lower cervical facet dislocation.Methods: The application of all reduction techniques for lower cervical facet dislocation, including closed reduction, anterior-only, posterior-only, and combined approach reduction, is reviewed and discussed. Recent advancements on the novel techniques of reduction are also described. The principles of various techniques for reduction of cervical facet dislocation are described in detail.Results: All reduction techniques are useful. The anterior-only surgical approach appears to be the most popular approach. Moreover, many novel or modified reduction and fixation methods have been introduced in recent years.Conclusion: The selection of surgical approach depends on a combination of factors, including surgeon preference, patient factors, injury morphology, and inherent advantages and disadvantages of any given approach.

Contiguous-Level Unilateral Cervical Spine Facet Dislocation—A Report of a Less Discussed Subtype

Unilateral facet dislocation of subaxial cervical spine trauma is characterized by dislocation of inferior facet of superior vertebra over the superior facet of inferior vertebra. The injury is due to high-velocity trauma and associated with instability of spinal column. Such unilateral facet dislocations occurring at multiple adjacent levels for some reason are not reported or studied frequently. We have reported two cases of multiple-level dislocation of unilateral facets managed in our hospital with a review of available literature. The injury occurs as one side of the motion segment translates and rotates around an intact facet on the contralateral side. The major mechanism of injury is distractive flexion injury with axial rotation component. The injury is associated with instability secondary to loss of the discoligamentous complex. In cases with multiple-level dislocations of unilateral cervical facets, there are multiple mechanisms associated with significant neurological injury and most of them succumb at the site of injury. Only three other cases are available in English language literature. The neurological outcome is invariably poor. Multiple-level facet dislocations of subaxial cervical spine are reported sparsely in literature. We suspect that due to high-velocity nature of these injuries, most of them succumb soon after injury and not often reported. This article reports two cases of contiguous-level unilateral facet dislocation of subaxial cervical spine with associated injuries and the outcomes with review of literature.

Circumferential Operations of the Cervical Spine

Generally, a combined anterior and posterior cervical approach is associated with significant morbidity since it requires an extended operative time, greater intraoperative blood loss, and both anterior- and posterior-related surgical complications. However, there are some instances where a circumferential cervical fusion can be advantageous. Our objective is to discuss the indications for circumferential cervical spine procedures. A narrative review of the literature was performed. We include the indications for circumferential cervical approaches of the senior author (KDR). Indications for circumferential approaches include: (1) high-risk patients for pseudoarthrosis, (2) cervical deformity (e.g., degenerative, posttraumatic, cervicothoracic kyphosis), (3) cervical spine metastases (especially those with multilevel involvement), (4) cervical spine infection, (5) unstable cervical trauma, (6) movement disorders and cerebral palsy, (7) Multiply operated patient (especially postlaminectomy kyphosis and patients with massive ossification of the posterior longitudinal ligament), and when (8) early fusion is desirable. Circumferential procedures may be useful in many different cervical spine conditions requiring surgery. Despite its advantages, particularly with reducing the risk for pseudarthrosis, the benefits of a combined approach must be weighed against the risks associated with a dual approach. With appropriate preoperative planning, intraoperative decision-making, and surgical techniques, excellent clinical outcomes can be achieved.

Biomechanics, evaluation, and management of subaxial cervical spine injuries: A comprehensive review of the literature

STUDY DESIGN

Literature review.

OBJECTIVES

It has been reported that 2.4-3.7% of all blunt trauma victims suffer some element of cervical spine fracture, with the majority of these patients suffering from C3-7 (subaxial) involvement. With the improvement of first-response to trauma in the community, there are an increasing number of patients who survive their initial trauma and thus arrive at the hospital in need of further evaluation, stabilization, and management of these injuries.

METHODS

A comprehensive literature review compiled all relevant data on the biomechanics, imaging, evaluation, and medical and surgical management strategies for subaxial cervical spine fractures.

RESULTS

After review of the current literature on subaxial cervical spine biomechanics, imaging characteristics, evaluation strategies and surgical and orthopedic management techniques, the authors created a comprehensive review and protocol for management of subaxial cervical spine fractures.

CONCLUSIONS

The subaxial cervical spine is biomechanically and anatomically unique from the remainder of the spinal axis. Evaluation of subaxial cervical spine injuries is nuanced, and improper management of these injuries can lead to significant patient morbidity and even death. This provides a comprehensive review combining anatomy, imaging characteristics, evaluation strategies, and surgical and orthopedic management principles for subaxial cervical spine fractures.

Gardner Wells tongs modification in pre-operative management for cervical facet dislocation: A case report

Introduction

Cervical facet dislocations are one of the traumas that caused the neurological disability, and it is often found and shows a spectrum of facet fracture-dislocations. Cervical facet dislocation classified by the mean of mechanism into a flexion-distraction injury. The goal of the treatment is to reduce the dislocation in favour of the patient's condition and hospital facility.

Method

We reported a case of 32 years old female with incomplete spinal cord injury due to Flexion distraction injury of C4–C5 spine, cervical X-Ray shows anterior translation for about 50% of C4 relative to underlying C5 on lateral projection, the patient was diagnosed with bilateral facet cervical dislocation and treated by gradual closed reduction using Gardner Wells Tongs followed by posterior body stabilization and fusion.

Results

We initially load of 4 kg gradually along with continuous observation using lateral cervical radiograph and careful neurological assessment. The dislocation was finally reduced after gradual and dynamic loading with 14 kg load.

Discussion

There are several strategies for managing cervical injuries. Aside from whether the MRI has to perform before or after the reduction, the option on whether to use closed or open reduction can be managed at best in favour of the current condition.

Conclusion

Gardner Wells tongs is one of the best alternatives when the surgical approach is unavailable.

•

The dislocation reduced using gradual and dynamic loading with 14 kg load.

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Gardner Wells tongs is one of the best alternatives to surgery.

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Gradual and dynamic loading proof to be safe and effective.

When is the circumferential stabilization necessary for subaxial cervical fracture dislocations? The posterior ligament-bone injury classification and severity score: a novel treatment algorithm

OBJECTIVE

To propose a novel classification and scoring system called the posterior ligament-bone injury classification and severity score (PLICS) that offers a quantitative score to guide the need for posterior stabilization in addition to anterior reconstruction for subaxial cervical fracture dislocations (SCFDs).

METHODS

A total of 456 patients with SCFDs were prospectively included. Patients with PLICS ≥ 7 together with extremely unstable lateral mass fracture (EULMF) were classified as high-risk group, and the other patients were classified as low-risk group. For patients in the low-risk group, anterior-only reconstruction was performed; for patients in the high-risk group, additional posterior lateral mass fixation and fusion was performed after anterior reconstruction. Clinical outcome evaluation included using the visual analogue score (VAS), the Neck Disability Index (NDI), and the American Spinal Injury Association (ASIA) impairment scale. The change in the local sagittal alignment kyphosis Cobb angle was also recorded.

RESULTS

A total of 370 patients (81.1%) completed the minimal 12-month follow-ups, including 321 patients of low-risk group and 49 patients of high-risk group. Compared with the average VAS score preoperatively, the score at 12-month follow-up was significantly improved (from 6.1 + 0.3 to 1.1 + 0.2 in the low-risk group, P < 0.001; from 6.4 + 0.2 to 1.4 + 0.2 in the high-risk group, P < 0.001). The average NDI score at the 12-month follow-up was statistically low in the low-risk group (8.8 + 2.5 vs 13.8 + 3.4, P = 0.034). At least more than one grade improvement in the ASIA scale was observed in 80.5% of all patients. The local kyphosis Cobb angle at the injured segment averaged improved in both groups.

CONCLUSION

A PLICS score ≥ 7 together with EULMF can be the threshold for posterior stabilization in addition to anterior reconstruction for the patients with SCFDs.

Correlation of Anterior Interbody Graft Choice With Patient-Reported Outcomes in Cervical Spine Trauma

STUDY DESIGN

Ambispective observational cohort study.

OBJECTIVES

Synthetic graft usage avoids morbidity associated with harvest and reduces operative time. This study aims to evaluate outcomes of anterior cervical stabilization surgery using a synthetic cage in comparison with iliac crest bone graft (ICBG) following cervical spine trauma.

METHODS

An ambispective review was conducted on patients from the Alfred Trauma Registry. Consecutive patients treated at a level 1 trauma center, aged 18 years and older who were treated with standalone anterior cervical stabilization following spine trauma (2011-2016) were included in the study. Primary outcome measures were patient overall satisfaction, Neck Disability Index (NDI), neck pain 10-point visual analogue scale (VAS-neck) and arm pain 10-point visual analogue scale (VAS-arm). Secondary outcome measures were radiographic evidence of fusion and rate of revision surgery. All patients had follow-up for at least 1 year.

RESULTS

Between 2011 and 2016, 114 traumatic disc levels in 104 patients were treated. ICBG was used in 32% and polyetheretherketone (PEEK) cage in 68% of the patients. Both groups had similar demographic metrics. There was no significant difference in primary outcome measures between the graft types: (1) patient satisfaction (P = .15), (2) NDI (P = .11), (3) VAS-neck (P = .13), and (4) VAS-arm (P = .20). Radiology based fusion assessment 6 months postsurgery did not show statistical significance (P = .10). The rates of revision surgery were similar.

CONCLUSIONS

This study showed no significant difference in patient-reported outcome measures when comparing the usage of PEEK cage and ICBG in anterior stand alone cervical spine stabilization. Level 1 evidence studies are required to further investigate this finding.

Outcomes of Unstable Subaxial Cervical Spine Fractures Managed by Posteroanterior Stabilization and Fusion

STUDY DESIGN

Retrospective study.

PURPOSE

To evaluate clinical and radiological outcomes of unstable subaxial cervical spine injuries managed by both posterior tension band column stabilization and anterior decompression, stabilization, and fusion.

OVERVIEW OF LITERATURE

Unstable subaxial cervical spine injuries often involve disruption of the anterior column and posterior tension band osteoligamentous complex. Such injuries need immediate surgical intervention. Different methods of reduction and surgical approaches have been published in the literature, with lack of consensus on a uniform or standardized method. Controversy still exists regarding stabilization of unstable cervical fractures by anterior or posterior approach alone or combined approaches.

METHODS

We retrospectively evaluated 24 patients with post-traumatic unstable subaxial cervical spine injuries with their preoperative clinical details, X-ray, computed tomography, and magnetic resonance imaging of the cervical spine for fracture classification based on the mechanism of injury with status of disc herniation and posterior tension band disruption. All patients were managed by immediate reduction, posterior and anterior stabilization, and fusion in a single session of anesthesia. Data of all patients were analyzed with respect to pre- and postoperative neurological status based on American Spinal Injury Association grading, Visual Analog Scale score, the observation of bony fusion, and implant failure at 1, 3, 6, and 12 months. Data were analyzed using paired t-test.

RESULTS

All patients had solid fusion at the desired level with considerable neurological improvement at the 1-year follow-up.

CONCLUSIONS

In unstable cervical injuries, stabilization of disrupted posterior tension band increases the stability of anterior plating and fusion. This method of immediate reduction and circumferential stabilization is rapid, safe, and effective and has a low rate of complications.

Immediate reduction under general anesthesia and combined anterior and posterior fusion in the treatment of distraction-flexion injury in the lower cervical spine

BACKGROUND

Distraction-flexion of the lower cervical spine is a severe traumatic lesion, frequently resulting in paralysis. The optimal surgical treatment is controversial. It has been a challenge for orthopedic surgeons to manage distraction-flexion injury in the lower cervical spine while avoiding the risk of iatrogenic damage. Thus, safer strategies need to be designed and adopted.This study aimed to evaluate the clinical efficacy of immediate reduction under general anesthesia and combined anterior and posterior fusion in the treatment of distraction-flexion injury in the lower cervical spine.

METHODS

Twenty-four subjects of traumatic lower cervical spinal distraction-flexion were retrospectively analyzed from January 2010 to December 2013. Traffic accident was the primary cause of injury, with patients presenting with dislocated segments in C4-5 (n = 8), C5-6 (n = 10), and C6-7 (n = 6). Sixteen patients had unilateral facet dislocation and eight had bilateral facet dislocation. Spinal injuries were classified according to the American Spinal Injury Association (ASIA) impairment scale (2000 edition amended), with four cases of grade A, four cases of grade B, ten cases of grade C, four cases of grade D, and two cases of grade E. On admission, all patients underwent immediate reduction under general anesthesia and combined anterior and posterior fusion. The mean follow-up time was 3.5 years.

RESULTS

All operations were completed successfully, with no major complications. Postoperative X-rays showed satisfactory height for the cervical intervertebral space and recovery of the vertebral sequence. Bone fusion was completed within 4 to 6 months after surgery. Surgery also significantly improved neurological function in all patients.

CONCLUSION

Immediate reduction under general anesthesia and combined anterior and posterior fusion can be used to successfully treat distraction-flexion injury in the lower cervical spine, obtaining completed decompression, safe spinal re-alignment, and excellent immediate postoperative stability.

Is a patient-specific drill template via a cortical bone trajectory safe in cervical anterior transpedicular insertion?

BACKGROUND

This study aimed to develop patient-specific drill templates by computer numerical control or three-dimensional printing via two cortical bone trajectories (CBTs) and to evaluate their efficacies and accuracies in cervical anterior transpedicular insertion.

METHODS

Preoperative CT images of 20 cadaveric cervical vertebrae (C3-C7) were obtained. After image processing, patient-specific drill templates were randomly assigned to be constructed via two CBTs (CBT0 and CBT0.7) and manufactured by two methods (computer numerical control and three-dimensional printing). Guided by patient-specific drill templates, 3.5-mm-diameter screws were inserted into the pedicles. Postoperative CT scans were performed to evaluate the screw deviation in the entry point and midpoint of the pedicle. The screw positions were also graded.

RESULTS

Computer numerical control patient-specific drill templates had a significantly shorter manufacturing time compared to three-dimensional-printed patient-specific drill templates (p < 0.01). Absolute deviations at the entry point and midpoint of the pedicle had no significant differences on the transverse and sagittal planes (p > 0.05). There were no significant differences in screw positions (p = 0.3). However, three screw positions were in grade 3 in CBT0, while the others were in grade 1.

CONCLUSIONS

CBT0.7 appears to be a safe and feasible trajectory for cervical anterior transpedicular insertion. Bio-safe computer numerical control patient-specific drill templates can facilitate cervical anterior transpedicular insertion with good feasibility and accuracy.

Traumatic subaxial cervical facet subluxation and dislocation: epidemiology, radiographic analyses, and risk factors for spinal cord injury

BACKGROUND CONTEXT

Distractive flexion injuries (DFIs) of the subaxial cervical spine are major contributors to spinal cord injury (SCI). Prompt assessment and early intervention of DFIs associated with SCI are crucial to optimize patient outcome; however, neurologic examination of patients with subaxial cervical injury is often difficult, as patients commonly present with reduced levels of consciousness. Therefore, it is important to establish potential associations between injury epidemiology and radiographic features, and neurologic involvement.

PURPOSE

The aims of this study were to describe the epidemiology and radiographic features of DFIs presenting to a major Australian tertiary hospital and to identify those factors predictive of SCI. The agreement and repeatability of radiographic measures of DFI severity were also investigated.

STUDY DESIGN/SETTING

This is a combined retrospective case-control and reliability-agreement study.

PATIENT SAMPLE

Two hundred twenty-six patients (median age 40 years [interquartile range = 34]; 72.1% male) who presented with a DFI of the subaxial cervical spine between 2003 and 2013 were reviewed.

OUTCOME MEASURES

The epidemiology and radiographic features of DFI, and risk factors for SCI were identified. Inter- and intraobserver agreement of radiographic measurements was evaluated.

METHODS

Medical records, radiographs, and computed tomography and magnetic resonance imaging scans were examined, and the presence of SCI was evaluated. Radiographic images were analyzed by two consultant spinal surgeons, and the degree of vertebral translation, facet apposition, spinal canal occlusion, and spinal cord compression were documented. Multivariable logistic regression models identified epidemiology and radiographic features predictive of SCI. Intraclass correlation coefficients (ICCs) examined inter- and intraobserver agreement of radiographic measurements.

RESULTS

The majority of patients (56.2%) sustained a unilateral (51.2%) or a bilateral facet (48.8%) dislocation. The C6-C7 vertebral level was most commonly involved (38.5%). Younger adults were over-represented among motor-vehicle accidents, whereas falls contributed to a majority of DFIs sustained by older adults. Greater vertebral translation, together with lower facet apposition, distinguished facet dislocation from subluxation. Dislocation, bilateral facet injury, reduced Glasgow Coma Scale, spinal canal occlusion, and spinal cord compression were predictive of neurologic deficit. Radiographic measurements demonstrated at least a "moderate" agreement (ICC>0.4), with most demonstrating an "almost perfect" reproducibility.

CONCLUSIONS

This large-scale cohort investigation of DFIs in the cervical spine describes radiographic features that distinguish facet dislocation from subluxation, and associates highly reproducible anatomical and clinical indices to the occurrence of concomitant SCI.

A Novel Anterior Transpedicular Screw Artificial Vertebral Body System for Lower Cervical Spine Fixation: A Finite Element Study

A finite element model was used to compare the biomechanical properties of a novel anterior transpedicular screw artificial vertebral body system (AVBS) with a conventional anterior screw plate system (ASPS) for fixation in the lower cervical spine. A model of the intact cervical spine (C3–C7) was established. AVBS or ASPS constructs were implanted between C4 and C6. The models were loaded in three-dimensional (3D) motion. The Von Mises stress distribution in the internal fixators was evaluated, as well as the range of motion (ROM) and facet joint force. The models were generated and analyzed by mimics, geomagic studio, and ansys software. The intact model of the lower cervical spine consisted of 286,382 elements. The model was validated against previously reported cadaveric experimental data. In the ASPS model, stress was concentrated at the connection between the screw and plate and the connection between the titanium mesh and adjacent vertebral body. In the AVBS model, stress was evenly distributed. Compared to the intact cervical spine model, the ROM of the whole specimen after fixation with both constructs is decreased by approximately 3 deg. ROM of adjacent segments is increased by approximately 5 deg. Facet joint force of the ASPS and AVBS models was higher than those of the intact cervical spine model, especially in extension and lateral bending. AVBS fixation represents a novel reconstruction approach for the lower cervical spine. AVBS provides better stability and lower risk for internal fixator failure compared with traditional ASPS fixation.

Traumatic Cervical Unilateral and Bilateral Facet Dislocations Treated With Anterior Cervical Discectomy and Fusion Has a Low Failure Rate

STUDY DESIGN

Retrospective radiographic and chart review.

OBJECTIVE

To define the rate and associated risk factors of treatment failure of anterior cervical fusion for treatment of cervical facet dislocations.

METHODS

Between 2004 and 2014, a retrospective review at a single level 1 trauma center identified 38 patients with unilateral or bilateral dislocated facet(s) treated with anterior cervical discectomy and fusion (ACDF). Two patients were eliminated due to less than 30-day follow-up. Demographic data, initial neurological exams, surgical data, radiographic findings, and follow-up records were reviewed.

RESULTS

Of the 36 patients with facet dislocations treated with ACDF using a fixed locking plate, 16 were unilateral and 20 were bilateral. The mean age was 35 years (range 13-58). Mean follow-up was 323 days (range 30-1998). There were 3 treatment failures (8%). Three of 7 (43%) endplate fractures failed (P < .01), and 1/28 (4%) facet fractures failed (P = .13). The mean time to failure was 4 weeks (1-7 weeks). One treatment failure had a facet fracture, and all 3 failures had an associated endplate fracture.

CONCLUSION

Treatment failure occurred in 3 out of 36 (8%) patients with facet fracture dislocations treated with anterior cervical discectomy, fusion, and plating. Rates of failure are lower than has been previously reported. Endplate fractures of the inferior level in jumped facets appears to be a major risk factor of biomechanical failure. However, a facet fracture may not be a risk factor for failure. In the absence of an endplate fracture, ACDF is a reasonable treatment option in patients with single-level cervical facet dislocation.

Anterior Surgical Fixation for Cervical Spine Flexion-Distraction Injuries

BACKGROUND

Optimal surgical management for flexion-distraction cervical spine injuries remains controversial with current guidelines recommending anterior, posterior, and circumferential approaches. Here, we determined the incidence of and examined risk factors for clinical and radiographic failure in patients with 1-segment cervical distraction injuries having undergone anterior surgical fixation.

METHODS

A retrospective review of 57 consecutive patients undergoing anterior fixation for subaxial flexion-distraction cervical injuries between 2008 and 2012 at our institution was performed. The primary outcome was the number of patients requiring additional surgical stabilization and/or radiographic failure. Data collected included age, gender, mechanism and level of injury, facet pattern injury, and vertebral end plate fracture.

RESULTS

A total of 6 patients failed clinically and/or radiographically (11%). Four patients (7%) required additional posterior fixation. Although 2 other patients identified met radiographic failure criteria, at follow-up they had fused radiographically, were stable clinically, and no further treatment was pursued. Progressive kyphosis and translation were found to be significantly correlated with need for revision (P < 0.05 and P = 0.02, respectively). No differences were identified for all other clinical and radiologic factors assessed, including unilateral or bilateral facet injury, facet fracture, and end plate fracture.

CONCLUSION

This study contributes to the growing body of evidence supporting anterior fixation alone for flexion-distraction injuries. Findings suggest that current measurements of radiographic failure including segmental translation and kyphosis may predict radiographic failure and need for further surgical stabilization in some patients. Future follow-up studies assessing for independent risk factors for anterior approach failure with a validated predictive scoring model should be considered.

LEVEL OF EVIDENCE IN THE PLACEMENT OF TRANSPEDICULAR SCREWS IN SUBAXIAL CERVICAL SPINE

ABSTRACT The high-energy trauma mainly involves vertebral lesions and 6% occur in the cervical region. This poses a challenge to spine surgeons in surgical decision-making, both in terms of approach as the instrumentation. International recommendations establish that the procedures performed are reproducible, safe, and effective. The techniques for placement of pedicle screws are complicated and have been based on intraoperative navigation (limited by cost) and fluoroscopy (greater exposure of health care professionals and patients to radiation). Therefore, the freehand technique is an option. The goal was to identify the level of evidence and grade of recommendation in the medical literature regarding the safety and efficacy of pedicle screw instrumentation with freehand technique in subaxial cervical spine. To this end, we carried out a systematic review with the following MeSH terms: safety, efficacy, vertebral artery. Articles were evaluated twice in a standardized and blind way by two observers skilled in systematic analysis, after CLEIS 3401 authorization in November 2014. Due to the nature of the study and the variables, articles with a high level of evidence and grade of recommendation were not found. Level of Evidence obtained on safety and efficacy in the placement of pedicle screws in subaxial column with freehand technique: 2b. Degree of Recommendation obtained on safety and efficacy in the placement of pedicle screws in subaxial column with freehand technique: B, favorable recommendation.

Influence of graft size on spinal instability with anterior cervical plate fixation following in vitro flexion-distraction injuries

BACKGROUND CONTEXT

Anterior cervical discectomy and fusion with plating (ACDFP) is commonly used for the treatment of distractive-flexion cervical spine injuries. Despite the prevalence of ACDFP, there is little biomechanical evidence for graft height selection in the unstable trauma scenario.

PURPOSE

This study aimed to investigate whether changes in graft height affect the kinematics of instrumented ACDFP C5-C6 motion segments in the context of varying degrees of simulated facet injuries.

STUDY DESIGN

In vitro cadaveric biomechanical study was used as study design.

METHODS

Seven C5-C6 motion segments were mounted in a custom spine simulator and taken through flexibility testing in axial rotation, lateral flexion, and flexion-extension. Specimens were first tested intact, followed by a standardized injury model (SIM) for a unilateral facet perch at C5-C6. The stability of the ACDFP approach was then examined with three graft heights (computed tomography-measured disc space height, disc space height undersized by 2.5 mm, and disc space height oversized by 2.5 mm) within three increasing unstable injuries (SIM, an added unilateral facet fracture, and a simulated bilateral facet dislocation injury).

RESULTS

In all motions, regardless of graft size, ACDFP reduced range of motion (ROM) from the SIM state. For flexion-extension, the oversized graft had a larger decrease in ROM compared with the other graft sizes (p<.05). Between graft sizes and injury states, there were a number of interactions in axial rotation and lateral flexion, where specifically in the most severe injury, the undersized graft had a larger decrease in ROM than the other two sizes (p<.05).

CONCLUSIONS

This study found that graft size did affect the kinematic stability of ACDFP in a series of distractive-flexion injuries; the undersized graft resulted in both facet overlap and locking of the uncovertebral joints leading to decreased ROM in lateral bending and axial rotation, whereas an oversized graft provided larger ROM decreases in flexion-extension. As such, a graft that engages the uncovertebral joint may be more advantageous in providing a rigid environment for fusion with ACDFP.

In vitro biomechanical evaluation of four fixation techniques for distractive-flexion injury stage 3 of the cervical spine

PURPOSE

Anterior plate fixation has been reported to provide satisfactory results in cervical spine distractive flexion (DF) injuries stages 1 and 2, but will result in a substantial failure rate in more unstable stage 3 and above. The aim of this investigation was to determine the biomechanical properties of different fixation techniques in a DF-3 injury model where all structures responsible for the posterior tension band mechanism are torn.

METHODS

The multidirectional three-dimensional stiffness of the subaxial cervical spine was measured in eight cadaveric specimens with a simulated DF-3 injury at C5-C6, stabilized with four different fixation techniques: anterior plate alone, anterior plate combined with posterior wire, transarticular facet screws, and a pedicle screw-rod construct, respectively.

RESULTS

The anterior plate alone did not improve stability compared to the intact spine condition, thus allowing considerable range of motion around all three cardinal axes (p > 0.05). The anterior plate combined with posterior wire technique improved flexion-extension stiffness (p = 0.023), but not in axial rotation and lateral bending. When the anterior plate was combined with transarticular facet screws or with a pedicle screws-rod instrumentation, the stability improved in flexion-extension, lateral bending, and in axial rotation (p < 0.05).

CONCLUSIONS

These findings imply that the use of anterior fixation alone is insufficient for fixation of the highly unstable DF-3 injury. In these situations, the use of anterior fixation combined with a competent posterior tension band reconstruction (e.g. transarticular screws or a posterior pedicle screws-rod device) improves segmental stability.

Biomechanical analysis of differential pull-out strengths of bone screws using cervical anterior transpedicular technique in normal and osteoporotic cervical cadaveric spines

STUDY DESIGN

Biomechanical in vitro study.

OBJECTIVE

To determine whether the peak pull-out force (PPF) of cervical anterior transpedicular screw (ATPS) fixed in osteoporotic vertebrae positively influence screw stability or not before and after fatigue.

SUMMARY OF BACKGROUND DATA

Multilevel cervical spine procedures with osteoporosis can challenge the stability of current screw-and-plate systems. A second surgical posterior approach is coupled with potential risks of increased morbidity and complications. Hence, anterior cervical instrumentation that increases primary construct stability, while avoiding the need for posterior augmentation, would be valuable.

METHODS

Sixty formalin-fixed vertebrae at different levels were randomly selected. The vertebrae were divided into healthy controls (groups A1, A2), osteoporotic controls (B1, B2), healthy ATPS groups (C1, C2), osteoporotic ATPS groups (D1, D2), and osteoporotic restoration controls (E1, E2). The procedure of ATPS insertion was simulated with 2 pilot holes being drilled on each side of 20 vertebral bodies that were implanted with either vertebral screw or polymethylmethacrylate. Each side randomly received either instant PPF or PPF beyond fatigue (2.5 Hz; 20,000 times).

RESULTS

The prefatigue PPFs were significantly higher than the postfatigue PPFs in all groups (group A: 366.06 ± 58.78 vs. 248.93 ± 57.21 N; group B: 275.58 ± 23.18 vs. 142.79 ± 44.78 N; group C: 635.99 ± 185.28 vs. 542.57 ± 136.58 N; group D: 519.22 ± 122.12 vs. 393.16 ± 192.07 N, and group E: 431.78 ± 75.77 vs. 325.74 ± 95.10 N). The postfatigue PPFs were reduced by 32.00% (group A), 48.19% (group B), 14.69% (group C), 24.28% (group D), and 24.72% (group E). The acute and postfatigue PPFs of both control groups were significantly lower than that of ATPS groups (P < 0.05). The cyclic osteoporosis ATPS group achieved the same PPF compared with the vertebral restoration screw group.

CONCLUSION

The findings of this study suggest that instant PPF and fatigue resistance capability of an ATPS fixation were significantly better than other control groups, especially in the osteoporotic vertebrae.

Treatment of traumatic spondylolisthesis of the lower cervical spine with concomitant bilateral facet dislocations: risk of respiratory deterioration

BACKGROUND

This study aimed to retrospectively examine 36 cases of bilateral cervical facet dislocations (BCFD) of the lower cervical spine who were at risk for respiratory deterioration.

METHODS

The cases of 36 subjects with BCFD of the lower cervical spine who failed to achieve closed reduction were retrospectively studied. The extents of neurological injuries included posterior neck pain without neurological deficit (n=2), incomplete spinal cord injury (ISCI) (n=21), and complete spinal cord injury (CSCI) (n=13).

RESULTS

Among the subjects, 26 (72.22%) had dyspnea, 6 required mechanical ventilation due to respiratory muscle paralysis, 11 required tracheostomy, and 9 required intubation. All patients received posterior approach reduction, stabilization, and fusion treatment for BCFD in one operative session. For the 26 quadriparetic patients with dyspnea, priority was given to treating their respiratory problems. For the other 10 patients without dyspnea, surgical treatment for irreducible lower cervical spine dislocation was given priority. After an average follow-up period of 63 months, 21 complications were found, but all patients exhibited fusion. Twenty-one patients with ISCI exhibited improvements in their conditions of 1 or 2 grades on the American Spinal Injury Association scale, whereas those with CSCI did not improve. All 26 apnea cases improved. The majority (26) of the 36 cases with BCFD of the lower cervical spine suffered dyspnea.

CONCLUSIONS

Although further study is required, our study suggests that the posterior surgical approach to the cervical spine is safe and effective for patients with traumatic spondylolisthesis of the lower cervical spine concomitant with BCFD who are at risk of respiratory deterioration.

Surgical options in the treatment of subaxial cervical fractures: a retrospective cohort study

OBJECTIVE

To compare clinical and radiographic parameters and outcomes in patients undergoing anterior vs. posterior surgery in unstable cervical subaxial spine fractures.

METHODS

We analyzed a group of 33 patients with reducible cervical subaxial fractures. Patients underwent anterior or posterior cervical instrumentation. Inpatient and outpatient records were retrospectively reviewed, and the multiple pre-operative and post-operative clinical and radiographic factors were recorded and analyzed.

RESULTS

Posterior cervical fixation was performed in 15 patients, and anterior cervical fixation in 18 patients. Operative time, blood loss, and number of levels instrumented were all significantly less in the anterior than the posterior cervical group. There was no difference in patient age, surgical complications, follow-up ASIA score, Rand SF-36 evaluation, or cost analysis between the two groups. Mean follow-up time was 11.8±7 months. All patients achieved bony fusion and good alignment at follow-up.

CONCLUSIONS

In patients with reducible cervical subaxial dislocations, posterior cervical fixation entails a larger number of fused segments. Anterior surgery is associated with shorter operative times and less blood loss. Anterior instrumentation with interbody grafting can be the initial choice of treatment for stabilization for this subgroup of patients. Posterior surgery is indicated if radiographs after anterior instrumentation show failure.

Construction and accuracy assessment of patient-specific biocompatible drill template for cervical anterior transpedicular screw (ATPS) insertion: an in vitro study

Background

With the properties of three-column fixation and anterior-approach-only procedure, anterior transpedicular screw (ATPS) is ideal for severe multilevel traumatic cervical instabilities. However, the accurate insertion of ATPS remains challenging. Here we constructed a patient-specific biocompatible drill template and evaluated its accuracy in assisting ATPS insertion.

Methods

After ethical approval, 24 formalin-preserved cervical vertebrae (C2–C7) were CT scanned. 3D reconstruction models of cervical vertebra were obtained with 2-mm-diameter virtual pin tracts at the central pedicles. The 3D models were used for rapid prototyping (RP) printing. A 2-mm-diameter Kirschner wire was then inserted into the pin tract of the RP model before polymethylmethacrylate was used to construct the patient-specific biocompatible drill template. After removal of the anterior soft tissue, a 2-mm-diameter Kirschner wire was inserted into the cervical pedicle with the assistance of drill template. Cadaveric cervical spines with pin tracts were subsequently scanned using the same CT scanner. A 3D reconstruction was performed of the scanned spines to get 3D models of the vertebrae containing the actual pin tracts. The deviations were calculated between 3D models with virtual and actual pin tracts at the middle point of the cervical pedicle. 3D models of 3.5 mm-diameter screws were used in simulated insertion to grade the screw positions.

Findings

The patient-specific biocompatible drill template was constructed to assist ATPS insertion successfully. There were no significant differences between medial/lateral deviations (P = 0.797) or between superior/inferior deviations (P = 0.741). The absolute deviation values were 0.82±0.75 mm and 1.10±0.96 mm in axial and sagittal planes, respectively. In the simulated insertion, the screws in non-critical position were 44/48 (91.7%).

Conclusions

The patient-specific drill template is biocompatible, easy-to-apply and accurate in assisting ATPS insertion. Its clinical applications should be further researched.

Biomechanical evaluation of a low profile, anchored cervical interbody spacer device in the setting of progressive flexion-distraction injury of the cervical spine

INTRODUCTION

Anterior cervical decompression and fusion is a well-established procedure for treatment of degenerative disc disease and cervical trauma including flexion-distraction injuries. Low-profile interbody devices incorporating fixation have been introduced to avoid potential issues associated with dissection and traditional instrumentation. While these devices have been assessed in traditional models, they have not been evaluated in the setting of traumatic spine injury. This study investigated the ability of these devices to stabilize the subaxial cervical spine in the presence of flexion-distraction injuries of increasing severity.

METHODS

Thirteen human cadaveric subaxial cervical spines (C3-C7) were tested at C5-C6 in flexion-extension, lateral bending and axial rotation in the load-control mode under ±1.5 Nm moments. Six spines were tested with locked screw configuration and seven with variable angle screw configuration. After testing the range of motion (ROM) with implanted device, progressive posterior destabilization was performed in 3 stages at C5-C6.

RESULTS

The anchored spacer device with locked screw configuration significantly reduced C5-C6 flexion-extension (FE) motion from 14.8 ± 4.2 to 3.9 ± 1.8°, lateral bending (LB) from 10.3 ± 2.0 to 1.6 ± 0.8, and axial rotation (AR) from 11.0 ± 2.4 to 2.5 ± 0.8 compared with intact under (p < 0.01). The anchored spacer device with variable angle screw configuration also significantly reduced C5-C6 FE motion from 10.7 ± 1.7 to 5.5 ± 2.5°, LB from 8.3 ± 1.4 to 2.7 ± 1.0, and AR from 8.8 ± 2.7 to 4.6 ± 1.3 compared with intact (p < 0.01). The ROM of the C5-C6 segment with locked screw configuration and grade-3 F-D injury was significantly reduced from intact, with residual motions of 5.1 ± 2.1 in FE, 2.0 ± 1.1 in LB, and 3.3 ± 1.4 in AR. Conversely, the ROM of the C5-C6 segment with variable-angle screw configuration and grade-3 F-D injury was not significantly reduced from intact, with residual motions of 8.7 ± 4.5 in FE, 5.0 ± 1.6 in LB, and 9.5 ± 4.6 in AR.

CONCLUSIONS

The locked screw spacer showed significantly reduced motion compared with the intact spine even in the setting of progressive flexion-distraction injury. The variable angle screw spacer did not sufficiently stabilize flexion-distraction injuries. The resulting motion for both constructs was higher than that reported in previous studies using traditional plating. Locked screw spacers may be utilized with additional external immobilization while variable angle screw spacers should not be used in patients with flexion-distraction injuries.

A traumatic, high-energy and unstable fracture of the C5 vertebra managed with kyphoplasty: a previously unreported case

Unstable cervical fractures commonly require fusion surgery. We present a case of an unstable cervical fracture (AO classification A2.2) affecting the fifth cervical vertebra which was managed by kyphoplasty to achieve a pain-free, functional and stable outcome. The decision to undertake a kyphoplasty procedure was made in the hope of preserving motion and limiting the degree of future adjacent segment disease. We believe this to be the first case of the use of kyphoplasty to be published in the literature in relation to a traumatic cervical fracture. Additionally, at one-year follow-up the patient reports no pain, a near full range of motion in the cervical spine and no neurological deficit.

Unilateral facet dislocations: Is surgery really the preferred option?

Study design: Systematic review.

Objective: To compare the safety and effectiveness of initial surgery versus nonoperative management of unilateral facet dislocations with or without fractures.

Summary of background: Unilateral facet injuries represent between 6%–10% of all cervical spine injuries and yet optimal treatment for these injuries has not been established. The surgeon is faced with the decision of whether to manage the injury operatively or nonoperatively. Providing evidence to support this decision is necessary and is the rationale behind this article.

Methods: A systematic review of the English language literature was undertaken for articles published between 1970 and August 2009. Electronic databases and reference lists of key articles were searched to identify studies evaluating surgery and nonoperative management of unilateral facet dislocations. Bilateral facet dislocations, isolated facet fractures (without dislocation), and complete spinal cord injuries were excluded. Two independent reviewers assessed the level of evidence quality using the GRADE criteria and disagreements were resolved by consensus.

Results: We identified six articles meeting our inclusion criteria. Treatment failure, neurological deterioration, and persistent pain occurred more frequently in patients treated nonoperatively versus patients treated with surgery. Surgical patients experienced infections and surgical related complications not experience by those managed nonoperatively. Patients treated surgically after failed nonoperative management also experienced better outcomes than those who continued to be managed nonoperatively.

Conclusion: When faced with a patient requesting treatment recommendations for their acute unilateral facet dislocation, the surgeon can state that treatment failure, persistent pain, and neurological deterioration occur more frequently with nonoperative treatment based on the available literature. Ultimately it will be the preference of the patient that will decide between these two treatment approaches.

Mid- to long-term outcome of instrumented anterior cervical fusion for subaxial injuries

The management of patients with subaxial cervical injuries lacks consensus, particularly in regard to the decision which surgical approach or combination of approaches to use and which approach yields the best clinical outcome in the distinct injury. The trauma literature is replete with reports of surgical techniques, complications and gross outcome assessment in heterogeneous samples. However, data on functional and clinical outcome using validated outcome measures are scanty. Therefore, the authors performed a study on plated anterior cervical decompression and fusion for unstable subaxial injuries with focus on clinical outcome. For the purpose of a strongly homogenous subgroup of patients with subaxial injuries without spinal cord injuries, robust criteria were applied that were fulfilled by 28 patients out of an original series of 131 subaxial injuries. Twenty-six patients subjected to 1- and 2-level fusions without having spinal cord injury could be surveyed after a mean of 5.5 years (range 16-128 months). The cervical spine injury severity score averaged 9.6. Cross-sectional outcome assessment included validated outcome measures (Neck pain disability index, Cervical Spine Outcome Questionnaire, SF-36), the investigation of construct failure and successful surgical outcome were defined by strict criteria, the reconstruction and maintenance of local and total cervical lordosis, adjacent-segment degeneration and intervertebral motion, and the fusion-rate using an interobserver assessment. Self-rated clinical outcome was excellent or good in 81% of patients and moderate or poor in 19% that corresponded to the results of the validated outcome measures. Results of the NPDI averaged 12.4 +/- 12.7% (0-40). With the SF-36 mean physical and mental component summary scores were 47.0 +/- 9.8 (18.2-59.3) and 52.2 +/- 12.4 (14.6-75.3), respectively. Using merely non-constrained plates, construct failure was observed in 31% of cases and loss of local lordosis, expressed as a mean injury angle of 14 degrees, postoperative angle of -5.5 degrees and follow-up angle of -1 degree, was significant. However, total cervical lordosis was within the limits of normalcy (-24.3 degrees +/- 13.3) and fusion-rate was 88.5%. The progression of adjacent-level degeneration was shown to be significantly influenced by a decreased plate-to-disc-distance. Adjacent-level intervertebral motion was not altered due to the adjacent fusion, but reduced in the presence of advanced adjacent-level degeneration. Patients were more likely to maintain a high satisfaction level if they succeeded to maintain segmental lordosis (<0 degree), had a solid fusion, an increased plate-to-disc distance, and if they were judged to have a successful surgical outcome that included the absence of construct failure and reconstruction of lordosis within +/-1 SD of normalcy. Using validated outcome vehicles the interdependencies between radiographical, functional and clinical outcome parameters could be substantiated with statistically significant correlations. The use of validated outcome vehicles in a subgroup of patients with plated anterior cervical fusions for subaxial injuries is recommended. With future studies, it enables objective comparison of surgical techniques and related radiographical, functional and clinical outcome.

Anterior cervical pedicle screw and plate fixation using fluoroscope-assisted pedicle axis view imaging: a preliminary report of a new cervical reconstruction technique

Anterior procedures in the cervical spine are feasible in cases having anterior aetiologies such as anterior neural compression and/or severe kyphosis. Halo vests or anterior plates are used concurrently for cases with long segmental fixation. Halo vests are bothersome and anterior plate fixation is not adequately durable. We developed a new anterior pedicle screw (APS) and plate fixation procedure that can be used with fluoroscope-assisted pedicle axis view imaging. Six patients (3 men and 3 women; mean age, 54 years) with anterior multisegmental aetiology were included in this study. Their original diagnoses comprised cervical myelopathy and/or radiculopathy (n = 4), posterior longitudinal ligament ossification (n = 1) and post-traumatic kyphosis (n = 1). All patients underwent anterior decompression and strut grafting with APS and plate fixation. Mean operative time was 192 min and average blood loss was 73 ml. Patients were permitted to ambulate the next day with a cervical collar. Local sagittal alignment was characterised by 3.5 degrees of kyphosis preoperatively, which improved to 6.8 degrees of lordosis postoperatively and 5.2 degrees of lordosis at final follow-up. Postoperative improvement and early bony union were observed in all cases. There was no serious complication except for two cases of dysphagia. Postoperative imaging demonstrated screw exposure in one screw, but no pedicle perforation. APS and plate fixation is useful in selected cases of multisegmental anterior reconstruction of cervical spine. However, the adequate familiarity and experience with both cervical pedicle screw fixation and the imaging technique used for visualising the pedicle during surgery are crucial for this procedure.

Anterior cervical discectomy and fusion with a locked plate and wedged graft effectively stabilizes flexion-distraction stage-3 injury in the lower cervical spine: a biomechanical study

STUDY DESIGN

An in vitro three-dimensional (3D) flexibility test of human C3-C7 cervical spine specimens.

OBJECTIVE

To test the hypothesis that anterior cervical fusion with a wedged graft and a locked plate can effectively stabilize the cervical spine after complete anterior and posterior segmental ligamentous release.

SUMMARY OF BACKGROUND DATA

Distraction-flexion Stage 3 injuries of the lower cervical spine (bilateral facet dislocations) are usually reduced under awake cranial traction. When the magnetic resonance imaging reveals a traumatic disc prolapse, anterior cervical discectomy and fusion (ACDF) is usually recommended. Most authors advise combining ACDF with posterior instrumentation to address the insufficiency of the posterior elements. However, there is clinical evidence that ACDF with a locked plate alone suffices for the treatment of these injuries, especially in young patients. Still, there are no biomechanical studies on the effect of a locked plate on the complete anterior and posterior ligamentous-deficient young cervical spine under physiologic preload.

METHODS

Eight fresh frozen human lower cervical spines (C3-C7) from young donors (age, 44.5 years; range, 21-63 years) were used. A 3D flexibility test was conducted using a moment of 0.8 Nm without preload. Flexion-extension was additionally tested using a moment of 1.5 Nm under 0 and 150 N follower preload. Spines were tested first intact, then after complete C5-C6 discectomy with posterior longitudinal ligament resection and ACDF with a wedged bone graft and a rigid locked plate, and finally after complete release of the supraspinous, interspinous, and intertransverse ligaments; the facet capsules; and ligamentum flavum. RESULTS.: When tested under 0.8 Nm moment without preload, complete posterior and anterior ligamentous release did not significantly increase the ROM of the ACDF construct in flexion-extension (P > 0.025), lateral bending (P > 0.025), and axial rotation (P > 0.025). When tested under 1.5 Nm moment with or without a compressive preload, the complete posterior and anterior ligamentous release did not significantly affect the ROM of the ACDF construct (P > 0.01). The application of preload significantly reduced the motion at the C5-C6 ACDF construct with ligamentous disruption in comparison with the motion in the absence of a preload (P < 0.01).

CONCLUSION

Anterior cervical fusion with a wedged graft and a rigid constrained (locked) plate can effectively stabilize the nonosteoporotic cervical spine after complete posterior element injury when excessive ROM is prevented (for example, by the use of postoperative external immobilization). Even when the construct is subjected to higher moments, adequate stability can be achieved when physiologic preload is present. Osteoporosis and lack of sufficient preload due to poor neuromuscular control may affect long-term screw stability, and additional external immobilization may be needed until fusion matures.

Anterior versus combined anterior and posterior fixation/fusion in the treatment of distraction-flexion injury in the lower cervical spine

This study compared the results of combined anterior and posterior fixation/fusion with those of anterior fixation/fusion alone through a retrospective review of 50 patients with a distraction flexion injury of the cervical spine. Group A (n=28) had unilateral facet joint subluxation or dislocation (Allen stage I or II) and anterior fixation/fusion alone. Group B (n=10) had bilateral dislocation (Allen stage III) and anterior fixation/fusion alone. Group C (n=5) had unilateral subluxation or dislocation and combined anterior and posterior fixation/fusion. Group D (n=7) had bilateral dislocation or total dislocation (Allen stage III or IV) and combined anterior and posterior fixation/fusion. The following parameters were analyzed: the change in the vertebral height and Cobb's angle, neurologic recovery, fusion time, fusion rate, surgery time, and the rate of complications. The mean fusion time was 3.75+/-2.10, 6.00+/-2.82, 3.60+/-1.34, and 3.85+/-2.26 months in groups A, B, C, and D, respectively. Group B had a significantly longer mean fusion time than groups A and D (Mann-Whitney U-test, P=0,012, P=0.014). There was a significant difference in the operation time between groups A and B and groups C and D. There were no significant differences in the changes in vertebral height and Cobb's angle, fusion rate, and neurologic recovery. The complications encountered were three cases of distal screw loosening in group A (n=2) and B (n=1), and three cases of delayed union in group A (n=2) and B (n=1). There were no complications in groups C and D. In those with a bilateral dislocation, the fusion time was increased when only anterior fixation/fusion had been performed but the clinical results, such as neurologic recovery and complications, were similar in the four groups. Overall, anterior fixation/fusion alone in a bilateral dislocation is recommended as an alternative method.

Cervical anterior transpedicular screw fixation. Part I: Study on morphological feasibility, indications, and technical prerequisites

Multilevel cervical spine procedures can challenge the stability of current anterior cervical screw-and-plate systems, particularly in cases of severe three-column subaxial cervical spine injuries and multilevel plated reconstructions in osteoporotic bone. Supplemental posterior instrumentation is therefore recommended to increase primary construct rigidity and diminish early failure rates. The increasing number of successfully performed posterior cervical pedicle screw fixations have enabled more stable fixations, however most cervical pathologies are located anteriorly and preferably addressed by an anterior approach. To combine the advantages of the anterior approach with the superior biomechanical characteristics of cervical pedicle screw fixation, the authors developed a new concept of a cervical anterior transpedicular screw-and-plate system. An in vivo anatomical study was performed to explore the feasibility of anterior transpedicular screw fixation (ATPS) in the cervical spine. The morphological study was conducted based on 29 cervical spine CT scans from healthy patients and measurements were performed on the pedicle sizes, angulations, vertebral body depth, height and width at C2 to T1. Significant morphologic parameters for the new technique are discussed. These parameters include the sagittal and transverse intersection points of the pedicle axis with the anterior vertebral body wall, as well as the distances between sagittal intersection points from C2 to T1. On the basis of these results, standard spine models were reconstructed and used for the conceptual development of a preclinical release prototype of an anterior transpedicular screw-and-plate system. The morphological feasibility of the new technique is demonstrated, and its indications, biomechanical considerations, as well as surgical prerequisites are thoroughly discussed. In the future, the technique of cervical anterior transpedicular screw fixation might diminish the number of failures in the reconstruction of multilevel and three-column cervical spine instabilities, and avoid the need for supplemental posterior instrumentation.

Delayed presentation of cervical ligamentous instability without radiologic evidence

STUDY DESIGN

A case of delayed presentation of unstable cervical ligamentous injury without radiologic evidence is presented.

OBJECTIVES

To report a rare case of delayed presentation of cervical ligamentous injury without radiologic evidence, and to discuss diagnosis, initial management, and techniques of operative stabilization.

SUMMARY OF BACKGROUND DATA

The literature is reviewed.

METHODS

A 48-year-old man who sustained a nondisplaced unilateral C6 pillar fracture with no radiologic evidence of ligamentous injury returned for follow-up with radicular pain and bilateral perched facets at C5-C6.

RESULTS

Closed reduction of the cervical subluxation was performed via cervical traction, and subsequent surgical stabilization was undertaken with anterior cervical discectomy and instrumented arthrodesis of C5-C6 with structural interbody autograft. The patient wore a cervical brace for 6 weeks after surgery, and progressed to a stable fusion with pain resolution and no neurologic sequelae.

CONCLUSIONS

This is a rare reported case of delayed presentation of an unstable ligamentous injury in a nondisplaced cervical pillar fracture without initial radiologic evidence of instability. If any reason to suspect ligamentous injury exists, workup with upright cervical lateral radiographs, flexion/extension radiographs, or magnetic resonance imaging should be obtained. Awake, closed reduction with cervical traction followed by surgical stabilization with an anterior discectomy and instrumented arthrodesis with structural autograft achieved stable fixation.

Lessons learned from cervical pseudoarthrosis in ankylosing spondylitis

This case report illustrates three learning points about cervical fractures in ankylosing spondylitis, and it highlights the need to manage these patients with the neck initially stabilised in flexion. We describe a case of cervical pseudoarthrosis that is a rare occurrence after fracture of the cervical spine with ankylosing spondylitis. This went undetected until the development of myelopathic symptoms many months later. The neck was initially stabilised in flexion using tongs, and then slowly extended before anterior and posterior fixation was performed. The myelopathic symptoms resolved, and the patient had a good result at 18 months. We conclude that any increased movement of the spine after trauma in ankylosing spondylitis must be considered suspect and fully investigated.