Single level arthrodesis as treatment for midcervical fracture subluxation: a cohort study

Clinical evaluation of the efficacy of a new bone cement-injectable cannulated pedicle screw in the treatment of spondylolysis-type lumbar spondylolisthesis with osteoporosis: a retrospective study

Purpose

To investigate the clinical efficacy and safety of a bone cement-injectable cannulated pedicle screw (CICPS) in the treatment of spondylolysis-type lumbar spondylolisthesis with osteoporosis.

Methods

A retrospective study was conducted on 37 patients (Dual-energy X-ray bone density detection showed different degrees of osteoporosis) with spondylolysis-type lumbar spondylolisthesis who underwent lumbar spondylolisthesis reduction and fusion using a new type of injectable bone cement screw from May 2011 to March 2015. Postoperative clinical efficacy was evaluated by the Visual Analogue Scale (VAS) scores and the Oswestry Disability Index (ODI). Imaging indexes were used to evaluate the stability of internal fixation of the devices 1, 3, 6, and 12 months after surgery and annually thereafter. The safety of the CICPS was assessed by the prevalence of intraoperative and postoperative complications.

Results

A total of 124 CICPS were implanted intraoperatively. Bone cement leakage occurred in 3 screws (2.42%), and no clinical discomfort was found in any patients. All 37 patients were followed up with an average follow-up time of 26.6 ± 13.4 months (12–58 months). In the evaluation of the clinical effects of the operation, the average postoperative VAS score of the patients decreased from 4.30 ± 1.58 before surgery to 0.30 ± 0.70 after surgery (P < 0.001), and the ODI decreased from 47.27% ± 16.97% before surgery to 3.36% ± 5.70% after surgery (P < 0.001). No screw was loose, broken or pulled out.

Conclusion

CICPS is safe and effective in the treatment of spondylolysis-type lumbar spondylolisthesis complicated by osteoporosis.

Anterior-Alone Surgical Treatment for Subaxial Cervical Spine Facet Dislocation: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVE

Anterior-alone surgery has gained wider reception for subaxial cervical spine facets dislocation. Questions remain on its efficacy and safety as a stand-alone entity within the contexts of concurrent facet fractures, unilateral versus bilateral dislocations, anterior open reduction, and old dislocation.

METHODS

A systematic review was performed with search strategy using translatable MESH terms across MEDLINE, EMBASE, VHL Regional Portal, and CENTRAL databases on patients with subaxial cervical dislocation intervened via anterior-alone approach. Two reviewers independently screened for eligible studies. PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis) flow chart was adhered to. Nine retrospective studies were included. Narrative synthesis was performed to determine primary outcomes on spinal fusion and revisions and secondary outcomes on new occurrence or deterioration of neurology and infection rate.

RESULTS

Nonunion was not encountered across all contexts. A total of 0.86% of unilateral facet dislocation (1 out of 116) with inadequate reduction due to facet fragments between the facet joints removed its malpositioned plate following fusion. No new neurological deficit was observed. Cases that underwent anterior open reduction did not encounter failure that require subsequent posterior reduction surgery. One study (N = 52) on old dislocation incorporated partial corpectomy in their approach and limited anterior-alone approach to cases with persistent instability.

CONCLUSIONS

This systematic review supports the efficacy and success of anterior reduction, fusion, and instrumentation for cervical facet fracture dislocation. It is safe from a neurological standpoint. Revision rate due to concurrent facet fracture is low. Certain patients may require posteriorly based surgery or in specific cases combined anterior and posterior procedures.

Clinical efficacy of Bone Cement-injectable Cannulated Pedicle Screw Short Segment Fixation for Lumbar Spondylolisthesis with Osteoporosise

Many clinical studies have shown a satisfactory clinical efficacy using bone cement-augmented pedicle screw in osteoporotic spine, however, few studies have involved the application of this type of screw in lumbar spondylolisthesis. This study aims to investigate the mid-term clinical outcome of bone cement-injectable cannulated pedicle screw (CICPS) in lumbar spondylolisthesis with osteoporosis. From 2011 to 2015, twenty-three patients with transforminal lumbar interbody fusion (TLIF) using CICPS for lumbar spondylolisthesis were enrolled in the study. Oswestry Disability Index (ODI) and Visual Analogue Scale (VAS) were used to evaluate faunctional recovery and physical pain; and operation time, blood loss and hospitalization time were recorded, respectively. Radiograph and computed tomography of lumbar spine was performed to assess loss of the intervertebral disc space height, fixation loosening, and the rate of bony fusion. The average follow-up time of 23 patients was 22.5 ± 10.2 months (range, 6–36 months). According to VAS and ODI scores, postoperative pain sensation and activity function were significantly improved (p < 0.05). The height of the intervertebral disc space was reduced by 0.4 ± 1.1 mm, and the bone graft fusion rate was 100%. No cases of internal fixation loosening or screw pullout was observed. CICPS using cement augmentation may suggest as a feasible surgical technique in osteoporotic patients with lumbar spondylolisthesis.

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.

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.

Floating Lateral Mass Fractures of the Cervical Spine

STUDY DESIGN

Level I trauma center case series.

OBJECTIVE

The purpose of this study was (i) to characterize the floating lateral mass (FLM) fracture with the mechanism of injury, anatomical injury pattern, associated vascular injuries, neurological deficits, and key radiographic features; and (ii) to better understand the most effective method of treatment.

SUMMARY OF BACKGROUND DATA

An uncommon and poorly described subset of unilateral lateral mass fractures is FLM with fractures of the adjacent pedicle and lamina.

METHODS

Prospectively collected trauma registries were assessed to identify all patients with FLM fractures involving C3 to C7 between January 1, 2007 and December 31, 2012.

RESULTS

After institutional review board approval, 60 consecutive cases were identified from the trauma registries. The mean follow-up was 9 months (range 0-42 months). The most common level was C6. The most common mechanism of injury was a high speed motor vehicle accident (45%). Radiographic rotational displacement manifested as an anterolisthesis. CT showed facet joint widening at the level above and below in 63%. Vertebral artery injuries occurred in 22%. Neurological deficits occurred as radiculopathy in 38% and spinal cord injury in 18%. All eight patients, who were treated nonoperatively, developed subluxation despite external immobilization and six patients required surgery. Of the 58 patients treated operatively, 31 (53%) patients underwent a 2 level Anterior Cervical Discectomy and Fusion (ACDF) alone. Nine (15%) patients had one level ACDF, with 83% demonstrating radiographic failure. Posterior fusion alone or combined with ACDF/corpectomy was performed in 6 patients (10%) and 7 patients (12%), respectively.

CONCLUSION

A FLM fracture results from a high energy injury and involves two motion segments. Vertebral artery injuries and neurological deficits frequently occur. Magnetic Resonance demonstrates a significant disc injury in 81% of patients, usually at the lower level. Two level ACDF or Posterior Spinal Instrumented Fusion are effective means of treatment.

LEVEL OF EVIDENCE

3.

Treatment of isolated cervical facet fractures: a systematic review

OBJECT

In this clinically based systematic review of cervical facet fractures, the authors’ aim was to determine the optimal clinical care for patients with isolated fractures of the cervical facets through a systematic review.

METHODS

A systematic review of nonoperative and operative treatment methods of cervical facet fractures was performed. Reduction and stabilization treatments were compared, and analysis of postoperative outcomes was performed. MEDLINE and Scopus databases were used. This work was supported through support received from the Association for Collaborative Spine Research and AOSpine North America.

RESULTS

Eleven studies with 368 patients met the inclusion criteria. Forty-six patients had bilateral isolated cervical facet fractures and 322 had unilateral isolated cervical facet fractures. Closed reduction was successful in 56.4% (39 patients) and 63.8% (94 patients) of patients using a halo vest and Gardner-Wells tongs, respectively. Comparatively, open reduction was successful in 94.9% of patients (successful reduction of open to closed reduction OR 12.8 [95% CI 6.1–26.9], p < 0.0001); 183 patients underwent internal fixation, with an 87.2% success rate in maintaining anatomical alignment. When comparing the success of patients who underwent anterior versus posterior procedures, anterior approaches showed a 90.5% rate of maintenance of reduction, compared with a 75.6% rate for the posterior approach (anterior vs posterior OR 3.1 [95% CI 1.0–9.4], p = 0.05).

CONCLUSIONS

In comparison with nonoperative treatments, operative treatments provided a more successful outcome in terms of failure of treatment to maintain reduction for patients with cervical facet fractures. Operative treatment appears to provide superior results to the nonoperative treatments assessed.

Allograft versus autograft for pediatric posterior cervical and occipito-cervical fusion: a systematic review of factors affecting fusion rates

OBJECT Fusion rates are high for children undergoing posterior cervical fusion (PCF) and occipito-cervical fusion (OCF). Autologous bone has been widely used as the graft material of choice, despite the risk of donor-site morbidity associated with harvesting the bone, possibly because very low fusion rates were reported with posterior allograft cervical fusions in children several decades ago. Higher overall fusion rates using allograft in adults, associated with improvements in internal fixation techniques and the availability of osteoinductive substances such as bone morphogenetic protein (BMP), have led to heightened enthusiasm for the use of bank bone during pediatric PCF. A systematic review was performed to study factors associated with successful bone fusion, including the type of bone graft used. METHODS The authors performed a comprehensive PubMed search of English-language articles pertaining to PCF and OCF in patients less than 18 years old. Of the 561 abstracts selected, 148 articles were reviewed, resulting in 60 articles that had sufficient detail to be included in the analysis. A meta-regression analysis was performed to determine if and how age, fusion technique, levels fused, fusion substrate, BMP use, postoperative bracing, and radiographic fusion criteria were related to the pooled prevalence estimates. A systematic review of the literature was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. RESULTS A total of 604 patients met the specific inclusion and exclusion criteria. The overall fusion rate was 93%, with a mean age of 9.3 years and mean follow-up of 38.7 months. A total of 539 patients had fusion with autograft (94% fusion rate) and 65 patients with allograft (80% fusion rate). Multivariate meta-regression analysis showed that higher fusion rates were associated with OCF compared with fusions that excluded the occiput (p < 0.001), with the use of autograft instead of allograft (p < 0.001), and with the use of CT to define fusion instead of plain radiography alone. The type of internal fixation, the use of BMP, patient age, and the duration of follow-up were not found to be associated with fusion rates in the multivariate analysis. CONCLUSIONS Fusion rates for PCF are high, with higher rates of fusion seen when autograft is used as the bone substrate and when the occiput is included in the fusion construct. Further study of the use of allograft as a viable alternative to autograft bone fusion is warranted because limited data are available regarding the use of allograft in combination with more rigid internal fixation techniques and osteoinductive substances, both of which may enhance fusion rates with allograft.

The Effect of the PEEK Cage on the Cervical Lordosis in Patients Undergoing Anterior Cervical Discectomy

BACKGROUND:

Loss of cervical lordosis is a significant factor in the development of degeneration of the spine with aging. This degenerative changings of the cervical spine would cause pressure effect on the cervical root and/or medulla spinalis.

AIM:

Our goal is to understand the effect of the PEEK cage on cervical lordosis in the early postoperative period. Also, to interpret the effects of one- level, two- level, three-level and four- level disc pathologies on cervical lordosis.

MATERIAL AND METHODS:

We retrospectively investigated our archive, and we selected thirty-four patients undergoing anterior cervical discectomy and fusion with PEEK cage filled with demineralized bone matrix (ACDFP).

RESULTS:

We determined that ACDFP provides improvement in the cervical lordosis angle in both groups. Also, we found statistically significant difference between group 1 and 2 regarding causes of radiculomyelopathy statistically.

CONCLUSION:

We achieved better cervical lordotic angles at the postoperative period by implanting one-level, two-level, three-level or four-level PEEK cage filled with demineralized bone matrix. Also, the causes of cervical root and or medulla spinalis impingement were different in group1 and 2. While extruded cervical disc impingement was the first pathology in group 1, osteophyte formation was the first pathology in group 2.

Biomechanical evaluation of the impact of various facet joint lesions on the primary stability of anterior plate fixation in cervical dislocation injuries: a cadaver study

Object

Injuries of the subaxial cervical spine including facet joints and posterior ligaments are common. Potential surgical treatments consist of anterior, posterior, or anterior-posterior fixation. Because each approach has its advantages and disadvantages, the best treatment is debated. This biomechanical cadaver study compared the effect of different facet joint injuries on primary stability following anterior plate fixation.

Methods

Fractures and plate fixation were performed on 15 fresh-frozen intact cervical spines (C3–T1). To simulate a translation-rotation injury in all groups, complete ligament rupture and facet dislocation were simulated by dissecting the entire posterior and anterior ligament complex between C-4 and C-5. In the first group, the facet joints were left intact. In the second group, one facet joint between C-4 and C-5 was removed and the other side was left intact. In the third group, both facet joints between C-4 and C-5 were removed. The authors next performed single-level anterior discectomy and interbody grafting using bone material from the respective thoracic vertebral bodies. An anterior cervical locking plate was used for fixation. Continuous loading was performed using a servohydraulic test bench at 2 N/sec. The mean load failure was measured when the implant failed.

Results

In the group in which both facet joints were intact, the mean load failure was 174.6 ± 46.93 N. The mean load failure in the second group where only one facet joint was removed was 127.8 ± 22.83 N. In the group in which both facet joints were removed, the mean load failure was 73.42 ± 32.51 N. There was a significant difference between the first group (both facet joints intact) and the third group (both facet joints removed) (p < 0.05, Kruskal-Wallis test).

Conclusions

In this cadaver study, primary stability of anterior plate fixation for dislocation injuries of the subaxial cervical spine was dependent on the presence of the facet joints. If the bone in one or both facet joints is damaged in the clinical setting, anterior plate fixation in combination with bone grafting might not provide sufficient stabilization; additional posterior stabilization may be needed.

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.

Controversies in the treatment of cervical spine dislocations

BACKGROUND CONTEXT

Cervical spine dislocations represent an area of great controversy among spine surgeons.

PURPOSE

The purpose of this review is to present the specific areas of controversy and to provide a review of the literature.

STUDY DESIGN

A case of cervical spine dislocation is presented to illustrate the major controversies related to the treatment of cervical spine dislocations.

METHODS

A review of the literature is presented regarding the major controversial aspects of the treatment of cervical spine dislocations.

RESULTS

The major areas of controversy include the choice of imaging, closed versus open reduction and surgical approach.

CONCLUSIONS

Guidelines for the management of cervical spine dislocations are presented based on evidence-based medicine.

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.

Unilateral lateral mass-facet fractures with rotational instability: new classification and a review of 39 cases treated conservatively and with single segment anterior fusion

OBJECTIVE

This study examined the clinical and radiologic results of cervical spine injuries associated with a unilateral lateral mass-facet fracture (ULMFF) in an attempt to clarify the fracture pattern and treatment strategies using single-level anterior fusion.

METHODS

From July 2003 to June 2006, adult patients, who had sustained ULMFFs of the middle cervical spine, were reviewed retrospectively. The fractures were classified into six subtypes using roentgenogram and computed tomography imaging with three-dimensional analysis. Initially, 15 patients without severe translation and kyphosis were treated with external immobilization and 24 patients were treated surgically with anterior fusion. The fusion state and spinal alignment were evaluated at the follow-up visits.

RESULTS

Thirty-nine patients had 27 lateral mass fractures and 14 facet joint fractures. The lateral mass fractures were divided into the following four subtypes: unilateral spondylolithesis in 16, separation fracture in 5, comminution type in 4, and split type in 2. Facet fractures with/without facet dislocation were observed in seven patients. Twelve patients who received conservative management required delayed fusion due to persistent pain and late instability. Overall, 36 patients, with the exception of three cases with a successful result by external immobilization, underwent surgery using single-level anterior fixation with anterior plating. A poor radiologic outcome was observed in eight patients after the procedure. Five cases showed incomplete reduction or a failure of the reduction. Three cases had adjacent instability and malalignment despite the early fusion observed due to short-segment fusion in the separation type.

CONCLUSION

This retrospective review of ULMFF showed that nonsurgical treatment is usually unsuccessful, and early single-level anterior arthrodesis has a favorable outcome. However, exclusive two-level stabilization or pedicle screw fixation needs to be considered in the separation type.

Anterior cervical discectomy and fusion with structural allograft and plates for the treatment of unstable posterior cervical spine injuries

Object

The purpose of this study was to evaluate complications and radiographic and functional outcomes of isolated anterior stabilization surgery in which structural allograft and plates were used for posterior unstable subaxial cervical spine lateral mass, facet, and ligamentous injuries.

Methods

Between August 2003 and January 2008, 19 consecutive patients with unstable lateral mass, facet, and/or posterior ligamentous injuries of the subaxial cervical spine were treated by a single surgeon via an anterior approach. This was performed using structural allograft and plate fixation. Patients with any associated anterior vertebral fractures were excluded from the study. Autogenous bone grafts or bone graft substitutes were not used in any patient. The average age of the patients was 43 years (range 17–87 years) and the mean follow-up period was 20.4 months (range 6–48 months). Seventeen of the 19 patients participated in the study; the other 2 were lost to follow-up. Operative times, estimated blood loss, length of hospital stay (LOS), and perioperative complications were recorded for each patient. Radiographic outcomes included fusion scores and sagittal alignment measurements. Outcome scores with respect to neck pain, satisfaction with surgery, and function were recorded for each patient according to analog pain and satisfaction scales and the Neck Disability Index (NDI). Additionally, NDI and pain scores at final follow-up were compared with a group of healthy, age-matched controls.

Results

The average surgical time was 60 minutes (range 28–108 minutes), and the estimated blood loss averaged 48.9 ml per surgical procedure (range 20–150 ml). The LOS for the 13 patients who had no other associated injuries averaged 2.2 days (range 2–3 days). Fifteen of 17 patients achieved solid radiographic fusion, and no patient demonstrated instability. Only 1 patient had significant loss of the initial sagittal alignment correction at final follow-up. The average NDI score for the 17 patients was 6.5 (range 0–11), indicating mild disability and comparing favorably to a group of healthy age-matched controls. There was no statistical difference in pain scores for the trauma patients and control group at ultimate follow-up (1.5 vs 0.3, respectively). Satisfaction scores for the 17 trauma patients were high, averaging 94% (range 80–100%). Ten of the 11 patients with preoperative radiculopathy demonstrated complete resolution of this condition. Complications occurred in 1 patient with transient hoarseness and 1 with transient swallowing difficulty. There were no wound complications. Screw breakage occurred in 1 patient, and an additional patient required revision surgery for pseudarthrosis.

Conclusions

Anterior cervical discectomy and fusion performed using interbody structural allograft and plate fixation is highly effective in the treatment of unstable posterior cervical lateral mass, facet, and ligamentous injuries. This treatment option results in low intraoperative blood loss, short operating times, and a brief LOS. Radiographic outcomes with respect to segmental stability are excellent, and fusion rates with the use of structural allograft alone are high. Outcomes with respect to pain, function, and patient satisfaction are high, and complications are acceptably low.

Biomechanics of cervical facet dislocation

OBJECTIVES

The goal of this study was to compute the dynamic neck loads during simulated high-speed bilateral facet dislocation and investigate the injury mechanism.

METHODS

Ten osteoligamentous functional spinal units (C3/4, n = 4; C5/6, n = 3; C7/T1, n = 3) were prepared with muscle force replication, motion tracking flags, and a 3.3-kg mass rigidly attached to the upper vertebra. Frontal impacts of increasing severity were applied to the lower vertebra until dislocation was achieved. Inverse dynamics was used to calculate the dynamic neck loads during dislocation. Average peak impact acceleration required to cause dislocation ranged between 7.6 and 11.6 g. This resulted in dynamic neck loads applied at average peak rates of 906 Nm/s for flexion moment, 8017 N/ for anterior shear, and 8100 N/s for axial compression. To determine the temporal event patterns, the average occurrence times of the load and motion peaks were statistically compared (P <0.05).

RESULTS

Among average peak loads, axial compression of 233.6 N was first to occur followed by anterior shear force of 73.1 N and flexion moment of 30.7 Nm. Among average peak motions, axial separation of 5.3 mm was first to occur followed by flexion rotation of 63.1 degrees and anterior shear of 21.5 mm. Subsequently, average peak posterior shear force of 110.3 N was observed as the upper facet became locked in the intervertebral foramina. Average peak axial compression of 6.6 mm occurred significantly later than all preceding events.

CONCLUSIONS

During bilateral facet dislocation, the main loads included flexion moment and forces of axial compression and anterior shear. These loads caused flexion rotation, facet separation, and anterior translation of the upper facet relative to the lower. The present data help elucidate the injury mechanism of cervical facet dislocation.

Posterior cervical fixation with nitinol shape memory loop in the anterior-posterior combined approach for the patients with three column injury of the cervical spine : preliminary report

OBJECTIVE

The authors reviewed clinical and radiological outcomes in patients with three column injury of the cervical spine who had undergone posterior cervical fixation using Nitinol shape memory alloy loop in the anterior-posterior combined approach.

MATERIALS

Nine patients were surgically treated with anterior cervical fusion using an iliac bone graft and dynamic plate-screw system, and the posterior cervical fixation using Nitinol shape memory loop (Davydovtrade mark) at the same time. A retrospective review was performed. Clinical outcomes were assessed using the Frankel grading method. We reviewed the radiological parameters such as bony fusion rate, height of iliac bone graft strut, graft subsidence, cervical lordotic angle, and instrument related complication.

RESULTS

Single-level fusion was performed in five patients, and two-level fusion in four. Solid bone fusion was presented in all cases after surgery. The mean height of graft strut was significantly decreased from 20.46+/-9.97 mm at immediate postoperative state to 18.87+/-8.60 mm at the final follow-up period (p<0.05). The mean cervical lordotic angle decreased from 13.83+/-11.84 degrees to 11.37+/-6.03 degrees at the immediate postoperative state but then, increased to 24.39+/-9.83 degrees at the final follow-up period (p<0.05). There were no instrument related complications.

CONCLUSION

We suggest that the posterior cervical fixation using Nitinol shape memory alloy loop may be a simple and useful method, and be one of treatment options in anterior-posterior combined approach for the patients with the three column injury of the cervical spine.

Fibular allograft and anterior plating for dislocations/fractures of the cervical spine

BACKGROUND

Subaxial cervical spine dislocations are common and often present with neurological deficit. Posterior spinal fusion has been the gold standard in the past. Pain and neck stiffness are often the presenting features and may be due to failure of fixation and extension of fusion mass. Anterior spinal fusion which is relatively atraumatic is thus favored using autogenous grafts and cages with anterior plate fixation. We evaluated fresh frozen fibular allografts and anterior plate fixation for anterior fusion in cervical trauma.

MATERIALS AND METHODS

Sixty consecutive patients with single-level dislocations or fracture dislocations of the subaxial cervical spine were recruited in this prospective study following a motor vehicle accident. There were 38 males and 22 females. The mean age at presentation was 34 years (range 19-67 years). The levels involved were C5/6 (n = 36), C4/5 (n = 15), C6/7 (n = 7) and C3/4 (n = 2). There were 38 unifacet dislocations with nine posterior element fractures and 22 were bifacet dislocations. Twenty-two patients had neurological deficit. Co-morbidities included hypertension (n = 6), non-insulin-dependent diabetes mellitus (n = 2) and asthma (n = 1). All patients were initially managed on skull traction. Following reduction further imaging included Computerized Tomography and Magnetic Resonance Imaging. Patients underwent anterior surgery (discectomy, fibular allograft and plating). All patients were immobilized in a Philadelphia collar for eight weeks (range 7-12 weeks). Eight patients were lost to follow-up within a year. Follow-up clinical and radiological examinations were performed six-weekly for three months and subsequently at three-monthly intervals for 12 months. Pain was analyzed using the visual analogue scale (VAS). The mean follow-up was 19 months (range 14-39 months).

RESULTS

Eight lost to followup, hence 52 patients were considered for final evaluation. The neurological recovery was 1.1 Frankel grades (range 0-3) and two patients with root involvement recovered. At six months bony trabeculae at the graft-vertebrae interface were noted. There were 12 (20 %) cases of graft collapse and one case of angulation which showed no progression. At six months the VAS was 3 (range 0-6). There was no limitation of neck motion at six months in 47 patients.

CONCLUSION

Fresh frozen fibular allografts are suitable and cost-effective for anterior fusion in cervical trauma.