Posterior stabilization of cervical spine fractures and subluxations using plates and screws

The role of an anterior approach in the treatment of ankylosing spondylitis-associated cervical fractures: a systematic review and meta-analysis

OBJECTIVE

Cervical fractures in patients with ankylosing spondylitis can have devastating neurological consequences. Currently, several surgical approaches are commonly used to treat these fractures: anterior, posterior, and anterior-posterior. The relative rarity of these fractures has limited the ability of surgeons to objectively determine the merits of each. The authors present an updated systematic review and meta-analysis investigating the utility of anterior surgical approaches relative to posterior and anterior-posterior approaches.

METHODS

After a comprehensive literature search of the PubMed, Cochrane, and Embase databases, 7 clinical studies were included in the final qualitative and 6 in the final quantitative analyses. Of these studies, 6 compared anterior approaches with anterior-posterior and posterior approaches, while 1 investigated only an anterior approach. Odds ratios and 95% confidence intervals were calculated where appropriate.

RESULTS

A meta-analysis of postoperative neurological improvement revealed no statistically significant differences in gross rates of neurological improvement between anterior and posterior approaches (OR 0.40, 95% CI 0.10-1.59; p = 0.19). However, when analyzing the mean change in neurological function, patients who underwent anterior approaches had a significantly lower mean change in postoperative neurological function relative to patients who underwent posterior approaches (mean difference [MD] -0.60, 95% CI -0.76 to -0.45; p < 0.00001). An identical trend was seen between anterior and anterior-posterior approaches; there were no statistically significant differences in gross rates of neurological improvement (OR 3.05, 95% CI 0.84-11.15; p = 0.09). However, patients who underwent anterior approaches experienced a lower mean change in neurological function relative to anterior-posterior approaches (MD -0.46, 95% CI -0.60 to -0.32; p < 0.00001). There were no significant differences in complication rates between anterior approaches, posterior approaches, or anterior-posterior approaches, although complication rates trended lower in patients who underwent anterior approaches.

CONCLUSIONS

The results of this review and meta-analysis demonstrated the varying benefits of anterior approaches relative to posterior and anterior-posterior approaches in treatment of cervical fractures associated with ankylosing spondylitis. While reports demonstrated lower degrees of neurological improvement in anterior approaches, they may benefit patients with less-severe injuries if lower complication rates are desired.

Ankylosing spondylitis traumatic subaxial cervical fractures - An updated treatment algorithm

Ankylosing spondylitis (AS) is a rheumatologic disease characterized by ankylosis and ligament ossification of the spine with an elevated risk of vertebrae fractures at the cervical level or cervicothoracic junction. AS related cervical fractures (ASCFs) require early diagnosis and a treatment plan that considers the high risk for additional fractures to avoid neurological complications or death. We present the case of a patient with an ASCF and a review of the literature with key recommendations that shape our algorithm for the proper diagnosis and treatment of ASCFs. We present the case of a 29-year-old male with an ASCF at C5-C6 treated initially with a short segment instrumented arthrodesis that required an additional operation to properly stabilize and protect his spine. Based on our experience with this case and a review of the literature, we discuss three recommendations to improve ASCF management. These include the need for early computed tomography/magnetic resonance image for proper diagnoses, combined surgical approach with long-segment stabilization for maximum stability. Delayed diagnosis or revision surgery, both of which are common in these patients who present with a stiffened and osteoporotic spine, may lead to spinal cord injury or neurologic deficits. Our recommendations based on the most recent evidence can help surgeons better manage these patients and decrease their overall morbidity and mortality.

Cervical spine dislocation on ankylosing spondylitis: A case report

Treatment of cervical spine fracture in patients with ankylosing spondylitis is difficult. Biomechanical changes related to ossified ankylosing spondylitis spine make cervical spine fractures highly unstable. They cover the entire width of the spine inducing.

multidirectional instability and the risk of neurological injuries. Treatment is more difficult that in the nonossified spine. Different treatments have been proposed including anterior stabilization, posterior stabilization, or both. This paper present a case of an 55-year-old man followed for ankylosing spondylitis admitted for fracture dislocation of c5-c6 following a minimal trauma of which it was operated 4 times in order to obtain a satisfactory reduction and stabilization from which we drew the importance of the osteosynthesis by combined way.

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This paper presents a case of a 55-year-old man followed for ankylosing spondylitis admitted for fracture dislocation of c5-c6 following a minimal trauma of which it was operated 4 times.

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To obtain a satisfactory reduction and stabilization from which we drew the importance of the osteosynthesis by combined way.

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Orthopedic treatment alone is inadequate. Isolated anterior or posterior osteosynthesis is also insufficient. The rule should be the combination of both (360◦ fixation) when technically feasible.

The Neural Sulcus of the Cervical Vertebrae: A Review of Its Anatomy and Surgical Perspectives

The neural sulcus is a bony channel that spans the transverse process in the subaxial cervical spine. It is located between the anterior and posterior tubercles on either side of the transverse foramen, housing the spinal nerve as it passes through the intervertebral foramina. Although numerous studies have evaluated the anatomy of the cervical spine, very little data on detailed anatomy of the neural sulcus and its implication in cervical spine surgery exist. Here, we review the anatomy of the neural sulcus and surgical considerations. The neural sulcus has important surgical implications, and knowledge of its anatomy is important in considering and planning posterior cervical segmented instrumentation. This increases the ability of the neurosurgeon to choose the best suitable surgical approach to the subaxial cervical spine, allowing good outcomes for the patient.

Cortical Bone Trajectory Screws for Fixation Across the Cervicothoracic Junction: Surgical Technique and Outcomes

STUDY DESIGN

Clinical case series describing a novel surgical technique.

OBJECTIVE

Stabilization across the cervicothoracic junction (CTJ) poses technical difficulties which make this procedure challenging. The transition from cervical lordosis to thoracic kyphosis and the orientation of the lateral masses of the cervical spine compared with the pedicles of the thoracic spine create the need to accommodate for 2 planes of alignment when placing instrumentation. A novel surgical technique for instrumentation across the cervicothoracic junction is described.

METHODS

The use of cortical bone trajectory (CBT) technique for pedicle fixation in the upper thoracic spine is described in combination with cervical lateral mass or pedicle screws. The application in our first 12 patients for stabilization across the CTJ is described. Two case presentations illustrate the technique.

RESULTS

All the patients had rod screw constructs without the need to skip levels, there was no requirement for transverse connectors and only 1 plane of contouring was required.

CONCLUSIONS

The use of CBT technique has not been described for the upper thoracic spine. This technique avoids many technical problems associated with posterior instrumentation of the CTJ. The facility of their use in this application arises from the similar coronal plane entry points as the cervical lateral mass screws compared with the more lateral starting point of traditional thoracic pedicle screws. The technique has clinical equipoise to traditional thoracic pedicle screw insertion but with the benefits of an easier ability to perform the instrumentation and saving levels of fusion.

Posterior cervical spine crisscross fixation: Biomechanical evaluation

BACKGROUND

Biomechanical/anatomic limitations may limit the successful implantation, maintenance, and risk acceptance of posterior cervical plate/rod fixation for one stage decompression-fusion. A method of posterior fixation (crisscross) that resolves biomechanical deficiencies of previous facet wiring techniques and not reliant upon screw implantation has been devised. The biomechanical performance of the new method of facet fixation was compared to the traditional lateral mass plate/screw fixation method.

METHODS

Thirteen human cadaver spine segments (C2-T1) were tested under flexion-compression loading and four were evaluated additionally under pure-moment load. Preparations were evaluated in a sequence of surgical alterations with intact, laminectomy, lateral mass plate/screw fixation, and crisscross facet fixation using forces, displacements and kinematics.

FINDINGS

Combined loading demonstrated significantly lower bending stiffness (p < 0.05) between laminectomy compared to crisscross and lateral mass plate/screw preparations. Crisscross fixation showed a comparative tendency for increased stiffness. The increased overall motion induced by laminectomy was resolved by both fixation techniques, with crisscross fixation demonstrating a comparatively more uniform change in segmental motions.

INTERPRETATION

The crisscross technique of facet fixation offers immediate mechanical stability with resolution of increased flexural rotations induced by multi-level laminectomy. Many of the anatomic limitations and potentially deleterious variables that may be associated with multi-level screw fixation are not associated with facet wire passage, and the subsequent fixation using a pattern of wire connection crossing each facet joint exhibits a comparatively more uniform load distribution. Crisscross wire fixation is a valuable addition to the surgical armamentarium for extensive posterior cervical single-stage decompression-fixation.

Mini-open anterior approach for cervicothoracic junction fracture: technical note

Elderly patients with diffuse idiopathic skeletal hyperostosis are at high risk for falls, and 3-column unstable fractures present multiple challenges. Unstable fractures across the cervicothoracic junction are associated with significant morbidity and require fixation, which is commonly performed through a posterior open or percutaneous approach. The authors describe a novel, navigated, mini-open anterior approach using intraoperative cone-beam CT scanning to place lag screws followed by an anterior plate in a 97-year-old patient. This approach is less invasive and faster than an open posterior approach and can be considered as an option for management of cervicothoracic junction fractures in elderly patients with high perioperative risk profile who cannot tolerate being placed prone during surgery.

Pedicolaminar Fracture-Dislocation

A 28-year-old man presented to a level 1 trauma center with significant cervical spine pain after sliding into third base during a softball game. He struck his head on the thigh of the defensive player and had immediate pain in his neck and arm. He reported no loss of consciousness, no transient tetraplegia/paraplegia, and no loss of bowel and bladder control. After initial imaging, enhanced computed tomography scans were obtained.

Single anterior approach for cervical spine fractures at C5-T1 complicating ankylosing spondylitis

OBJECTIVES

To evaluate the outcomes of anterior approach for cervical spine fractures at C5-T1 in patients with ankylosing spondylitis (AS) and study the problems encountered in diagnosis and treatment.

PATIENTS AND METHODS

Ten patients with AS (all males; mean age 43.7±9.4 years) underwent anterior surgeries to treat fractures at C5-T1. Skull tractions were performed on patients with fracture dislocation preoperatively. After operation, all the patients wore a cervical collar for 3 months. Plain radiographs at follow-up were reviewed. If bone fusion could not be confirmed on plain radiograph, CT scan was employed. The pre- and postoperative neurological statuses were evaluated according to the Frankel grading system. Problems encountered in diagnosis and treatments were analyzed.

RESULTS

The mean follow-up was 41.2±22.7months. After operation, the displacements of fractures were significantly reduced(P<0.05). Bone fusions were observed in 9 patients at final follow-up. Frankel grades improved by 1.0±0.7 grade (P>0.05). Posterior complications occurred in four patients, including implants failure (n=1), subsidence of cage (n=1), hoarse voice (n=1) and pneumonias (n=2). The patient with implants failure required revision surgery and anterior-posterior fixation. Patient with subsidence of the titanium cage achieved bone fusion with prolonged cervical collar immobilization.

CONCLUSION

The diagnosis and treatment of cervical spine fractures at C5-T1 in AS patients are challenging, with high risk of neurological compromise and postoperative complications. The single anterior approach followed by postoperative immobilization with a cervical collar can yield acceptable results if the cases are properly selected.

Surgical Therapy of Cervical Spine Fracture in Patients With Ankylosing Spondylitis

The present study aimed to explore surgical treatments and assess the effects based on the features of cervical spine fracture in patients with ankylosing spondylitis (AS) and to summarize the experiences in perioperative management. Retrospective analysis was performed in 25 AS patients with cervical spine fracture treated in our hospital from January 2011 to December 2013. The patients were divided according to fracture segments, including 4 cases at C4 to C5, 8 cases at C5 to C6, and 13 cases at C6 to C7. Among them, 12 belonged to I type, 5 to II type, and 8 to III type based on the improved classification method for AS cervical spine fracture. The Subaxial Cervical Spine Injury Classification score for these patients was 7.2 ± 1.3, and the assessment of their neurological function states showed 6 patients (24%) were in American Spinal Injury Association (ASIA) A grade, 1 (4%) in ASIA B grade, 3 (12%) in ASIA C grade, 12 (48%) in ASIA D grade, and 3 (12%) in ASIA E grade. Surgical methods contained simple anterior approach alone, posterior approach alone, and combined posterior-anterior or anterior-posterior approach. The average duration of patients' hospital stay was 38.6 ± 37.6, and the first surgical methods were as follows: anterior approach alone on 6 cases, posterior surgery alone on 9 cases, and combined posterior-anterior or anterior-posterior approach on 10 patients. The median segments of fixation and fusion were 4.1 ± 1.4 sections. Thirteen patients developed complications. During 2 to 36 months of postoperative follow-up, 1 patient died of respiratory failure caused by pulmonary infections 2 months after leaving hospital. At the end of the follow-up, bone graft fusion was achieved in the rest of patients, and obvious looseness or migration of internal fixation was not observed. In addition, the preoperative neurological injury in 12 patients (54.5%) was also alleviated in different levels. AS cervical spine fracture, an unstable fracture, should be treated with operation, and satisfactory effects will be achieved after the individualized surgical treatment according to the improved classification method for AS cervical spine fracture.

Management of cervical fractures in ankylosing spondylitis: anterior, posterior or combined approach?

INTRODUCTION

Ankylosing spondylitis (AS) can lead to an increased risk of cervical fractures.

SOURCES OF DATA

A systematic review was undertaken using the keywords 'ankylosing spondylitis', 'spine fractures', 'cervical fractures', 'surgery' and 'postoperative outcomes' on Medline, Pubmed, Google Scholar, Ovid and Embase, and the quality of the studies included was evaluated according to the Coleman Methodology Score.

AREAS OF AGREEMENT

Surgery ameliorates neurological function in patients with unstable AS-related cervical fractures. The combined anterior/posterior and the posterior approaches are more effective than the anterior approach.

AREAS OF CONTROVERSY

The optimal approach, anterior, posterior or combined anterior/posterior, for the management of AS related cervical fractures has not been defined.

GROWING POINTS

Open reduction and internal fixation allows avoiding worsening and enhances neurological function in AS patients with cervical fractures.

AREAS TIMELY FOR DEVELOPING RESEARCH

Adequately powered randomized trials with appropriate subjective and objective outcome measures are necessary to reach definitive conclusions.

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.

Clinical outcomes of the surgical treatment of isolated unilateral facet fractures, subluxations, and dislocations in the pediatric cervical spine: report of eight cases and review of the literature

PURPOSE

We present a small series consisting of eight children with unilateral facet injury of the cervical spine treated surgically.

METHODS

A retrospective review was performed. Injury data, radiographs, surgical data, and outcomes (Neck Disability Index (NDI), Short Form 36 (SF-36), and Visual Analog Scale for Neck Pain (VAS-NP)) were collected from seven patients. A literature review was performed for one additional case.

RESULTS

Motor vehicle accidents (62 %, n = 5) and falls (38 %, n = 3) accounted for all injuries. The C6-7 level accounted for most of the injuries (37.5 %, n = 3). The mean NDI score with at least 3 months follow-up was 5.3 (n = 6, range, 1-12; standard deviation, 4.5), corresponding to mild disability. Of the norm-based SF-36 scale scores available (n = 6), the mean physical functioning (PF), role-physical (RP), and role-emotional (RE) scores were significantly less than the adult, age 18-24, norm-based means, with a mean difference of -6.4, -9.13, and -11.3, respectively (p value = 0.03, 0.001, and 0.01, respectively). The mean general health (GH) and vitality (VT) scores, however, were significantly greater than the adult, age 18-24, norm-based mean, with a mean difference of 7.82 and 10.3 (p = 0.04 and 0.02, respectively). VAS-NP showed a return to the "no pain" level at 3 months or more follow-up in all patients.

CONCLUSIONS

We suggest that surgical treatment of these injuries in the pediatric age group may lead to satisfactory clinical and radiographic outcomes, but HRQoL analysis suggests that patients remain physically and emotionally disabled to some degree after surgery.

Lateral mass screw fixation in the cervical spine: a systematic literature review

BACKGROUND

Lateral mass screw fixation with plates or rods has become the standard method of posterior cervical spine fixation and stabilization for a variety of surgical indications. Despite ubiquitous usage, the safety and efficacy of this technique have not yet been established sufficiently to permit "on-label" U.S. Food and Drug Administration approval for lateral mass screw fixation systems. The purpose of this study was to describe the safety profile and effectiveness of such systems when used in stabilizing the posterior cervical spine.

METHODS

A systematic search was conducted in MEDLINE and the Cochrane Collaboration Library for articles published from January 1, 1980, to December 1, 2011. We included all articles evaluating safety and/or clinical outcomes in adult patients undergoing posterior cervical subaxial fusion utilizing lateral mass instrumentation with plates or rods for degenerative disease (spondylosis), trauma, deformity, inflammatory disease, and revision surgery that satisfied our a priori inclusion and exclusion criteria.

RESULTS

Twenty articles (two retrospective comparative studies and eighteen case series) satisfied the inclusion and exclusion criteria and were included. Both of the comparative studies involved comparison of lateral mass screw fixation with wiring and indicated that the risk of complications was comparable between treatments (range, 0% to 7.1% compared with 0% to 6.3%, respectively). In one study, the fusion rate reported in the screw fixation group (100%) was similar to that in the wiring group (97%). Complication risks following lateral mass screw fixation were low across the eighteen case series. Nerve root injury attributed to screw placement occurred in 1.0% (95% confidence interval, 0.3% to 1.6%) of patients. No cases of vertebral artery injury were reported. Instrumentation complications such as screw or rod pullout, screw or plate breakage, and screw loosening occurred in <1% of the screws inserted. Fusion was achieved in 97.0% of patients across nine case series.

CONCLUSIONS

The risks of complications were low and the fusion rate was high when lateral mass screw fixation was used in patients undergoing posterior cervical subaxial fusion. Nerve root injury attributed to screw placement occurred in only 1% of 1041 patients. No cases of vertebral artery injury were identified in 758 patients. Screw or rod pullout, screw or plate breakage, and screw loosening occurred in <1% of the screws inserted.

Clinical application of combined fixation in the cervical spine using posterior transfacet screws and pedicle screws

The aim of the present study was to describe the clinical application of combined fixation in the cervical spine using posterior transfacet and pedicle screws. Ten patients with cervical disorders requiring stabilization were treated from May 2006 to December 2008. The operative details varied depending on indication, the need for decompression, and the number of levels to be included in the spinal construct. Radiographic analysis of the fusion was performed after surgery. A total of 23 transfacet screws were inserted at or caudal to the C4/5 facet. A total of 21 pedicle screws were placed. All patients underwent operative treatment without neurovascular complications. Fusion was achieved in all patients. When performed appropriately, the method of using posterior transfacet screws in the caudal cervical joints combined with pedicle screw fixation in the cephalic cervical spine is reliable and deserves more widespread use.

Descrição de técnica de redução cirúrgica das luxações facetárias da coluna cervical baixa por via anterior

O trabalho descreve uma técnica cirúrgica de redução anterior das luxações facetárias da coluna cervical e discute as indicações para cirurgia por via anterior para as luxações da coluna cervical baixa. A técnica descrita neste artigo oferece excelentes resultados, conforme revisão bibliográfica e dos resultados do Serviço, tendo sido aplicada em até 95% dos casos de fraturas-luxações. Não será abordada a apresentação de resultados neste trabalho, apenas a descrição e discussão da técnica aberta por via anterior. Observações de quarenta e um pacientes tratados nos últimos dez anos por esta técnica demonstram bons resultados quanto a pós-operatório menos doloroso, recuperação funcional extremamente rápida e complicações pouco frequentes.

Impact of lateral mass anatomic variation on ideal polyaxial screw head mobility: technical considerations

OBJECTIVE

To assess optimal angulation characteristics of lateral mass screws for subaxial (C3 to C6) fixation of the cervical spine in the neutral position.

BACKGROUND

In the typical Magerl or Anderson placement technique, the screw trajectory is ideally parallel to the facet joint. For the rod and screw to align properly, the screw head must rotate enough to become perpendicular to the rod. If the optimal angle for the screw head is limited by the screw design, abnormal torsional forces will be generated at the rod/screw interface inducing kyphosis. In this paper, we examined the spinal anatomy in patients with normal CTs to determine the necessary range of motion between tulip head and screw to prevent forced persuasion and abnormal cervical spine alignment.

METHODS

We examined subaxial radiographs of 292 vertebrae from C3 to C6 in 73 normal subjects. Computed tomography (CT) scans of the cervical spine with multiplanar reconstructions were evaluated in the axial and sagittal planes. A planned screw entry angle of 30° based upon the midpoint of the lateral mass was used in the axial plane, and parallel to the facet joint in the sagittal plane. The screw head angle (SHA) was then calculated from this 3D measured angle.

RESULTS

The measured SHA ranged from 27 to 60°. The average SHA was 43.8°. The average SHA was not significantly different between the levels measured with consistent range and standard deviation. Seventy-six percent (223/292) of levels measured required a SHA >40°, and 12% (36/292) required a SHA >50°.

CONCLUSION

The authors recommend using cervical instrumentation systems that allow for at least 55° of freedom of the polyaxial head to prevent abnormal segmental forces. In systems with lesser angulation, technique modifications must be applied to prevent translational forces.

Análise radiográfica do tratamento cirúrgico da fratura cervical baixa por via posterior

OBJETIVO: Avaliação da evolução radiográfica da lesão da coluna vertebral cervical tratada pela fixação posterior isolada. MÉTODOS: De 2000 a 2008 foram selecionados 23 pacientes que atenderam aos critérios de inclusão do estudo. Eram masculinos 91,3% e a idade média foi de 34 anos e quatro meses. O tempo de seguimento médio foi de 82 meses. Foi avaliado no exame de imagem pré-operatório, pós-operatório imediato e após seis meses de evolução o tipo de implante, a consolidação da artrodese, se houve soltura do implante, perda de redução, cifose segmentar, degeneração de nível adjacente e pseudartrose. RESULTADOS: Em relação ao método de síntese, 60,8% dos pacientes foram submetidos ao amarrilho interespinhoso, 26% à placa com parafusos de massa lateral e 13% à barra com parafusos de massa lateral. Dos pacientes submetidos à fixação com parafusos, nenhum apresentou complicações radiográficas e 35,7% dos pacientes submetidos à artrodese com amarrilho interespinhoso tiveram complicação, sendo a mais frequente a cifose segmentar. CONCLUSÃO: As lesões da coluna cervical submetidas a artrodese com parafuso de massa lateral apresentaram uma evolução radiográfica melhor do que as submetidas a fixação com amarrilho interespinhoso, tendo este último apresentado maior incidência de complicações na artrodese.

Operative techniques for cervical radiculopathy and myelopathy

The surgical treatment of cervical spondylosis and resulting cervical radiculopathy or myelopathy has evolved over the past century. Surgical options for dorsal decompression of the cervical spine includes the traditional laminectomy and laminoplasty, first described in Asia in the 1970's. More recently the dorsal approch has been explored in terms of minimally invasive options including foraminotomies for nerve root descompression. Ventral decompression and fusion techniques are also described in the article, including traditional anterior cervical discectomy and fusion, strut grafting and cervical disc arthroplasty. Overall, the outcome from surgery is determined by choosing the correct surgery for the correct patient and pathology and this is what we hope to explain in this brief review.

Increased in-hospital complications after primary posterior versus primary anterior cervical fusion

BACKGROUND

Although anterior (ACDF) and posterior cervical fusion (PCDF) are relatively common procedures and both are associated with certain complications, the relative frequency and severity of these complications is unclear. Since for some patients either approach might be reasonable it is important to know the relative perioperative risks for decision-making.

QUESTIONS/PURPOSES

The purposes of this study were to: (1) characterize the patient population undergoing ACDF and PCDF; (2) compare perioperative complication rates; (3) determine independent risk factors for adverse perioperative events; and (4) aid in surgical decision-making in cases in which clinical equipoise exists between anterior and posterior cervical fusion procedures.

METHODS

The National Inpatient Sample was used and entries for ACDF and PCDF between 1998 and 2006 were analyzed. Demographics and complication rates were determined and regression analysis was performed to identify independent risk factors for mortality after ACDF and PCDF.

RESULTS

ACDF had a shorter length of stay and their procedures were more frequently performed at nonteaching institutions. The incidence of complications and mortality was 4.14% and 0.26% among patients undergoing ACDF and 15.35% and 1.44% for patients undergoing PCDF, respectively. When controlling for overall comorbidity burden and other demographic variables, PCDF was associated with a twofold increased risk of a fatal outcome compared with ACDF. Pulmonary, circulatory, and renal disease were associated with the highest odds for in-hospital mortality.

CONCLUSIONS

PCDF procedures were associated with higher perioperative rates of complications and mortality compared with ACDF surgeries. Despite limitations, these data should be considered in cases in which clinical equipoise exists between both approaches.

LEVEL OF EVIDENCE

Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

A revisitation of distractive-extension injuries of the subaxial cervical spine: a cadaveric and radiographic soft tissue analysis

STUDY DESIGN

A biomechanical cadaveric and radiographic analyses.

OBJECTIVE

To identify and elaborate on specific anatomic soft tissue structures that are injured during various stages of a distractive-extension (DE) injury of the lower cervical spine and their role in angulation and posterior translation.

SUMMARY OF BACKGROUND DATA

Two DE stages (DES) of injury to the cervical spine have been described as follows: DES-1 and DES-2. However, the role of the soft tissue structures involved in such injuries has not been clearly defined. Furthermore, the importance of the facet capsules in DES injuries has not been well-addressed.

METHODS

A total of 15 adult cadaveric motion segments of the lower cervical spine were isolated and tested. Motion segments were mounted, with the cervical spine in extension, such that a distractive load was applied through the cephalad body. Anatomic supporting structures were serially sectioned from anterior to posterior to simulate varying degrees of soft-tissue disruption as occurring with the DE mechanism. Specimens were loaded at each stage of injury and measurements of angulation and posterior translation were recorded from fluoroscopic images by 2 independent observers.

RESULTS

A strong correlation was noted between the 2 sets of independent measurements. A statistical significant difference was noted between the degree of soft-tissue injury to the change in angulation and posterior translation (P < 0.001). The mean change in angulation and posterior translation was significantly greatest following sectioning of the anterior aspect of the facet capsules and to a lesser extent following sectioning of the posterior longitudinal ligament (PLL) (P < 0.001). A greater mean percent change between sequential sectioning of soft tissue structures was largely associated with posterior translation rather than angulation.

CONCLUSION

Sequentially greater angulation and posterior translation was seen after serial sectioning of the anterior facet capsule and to a lesser degree the PLL. This suggests that there are in fact 2 main "tethers" to angulation and posterior translation in the DE injury model, with the anterior facet capsule being the major stabilizer and to a lesser degree the PLL. Thus, based on our findings, it would appear that an expansion of the DE injury classification may be warranted, based on angulation and posterior translation, and regarded as DES-1, DES-2A, DES-2B, and DES-3. Such categorization based on the degree of angulation and posterior translation may prove advantageous in designing appropriate treatment strategies to address DE injuries of the lower cervical spine; however, further studies are needed to validate the clinical applications of such categorization.

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.

A treatment algorithm for the management of cervical spine fractures and deformity in patients with ankylosing spondylitis

Object

Patients with ankylosing spondylitis (AS) who present with cervical spine fractures represent a unique challenge to spine surgeons. These injuries often result in neurological deficits that necessitate early and aggressive surgical management with posterior and/or anterior fixation. The authors introduce a clinical problem-solving algorithm to assist in the surgical management of instability and deformity in this exigent patient population.

Methods

Thirteen patients with AS and fractures of the cervical spine were radiographically evaluated to determine if spinal realignment was obtainable with cervical manipulation or traction. Seven patients had flexible deformities that were stabilized with either anterior or posterior fixation only, and 6 patients had fixed deformities and required circumferential anterior–posterior instrumentation. All patients were observed for neurological outcome, radiographic evidence of bone fusion, and complications.

Results

With the use of the authors' treatment algorithm, all patients were able to achieve satisfactory spinal realignment and bone fusion; 92% of patients achieved postoperative stability or improvement in Nurick and modified Japanese Orthopaedic Association scale scores. One patient experienced neurological deterioration following surgery, and 1 patient died at an acute rehabilitative facility following discharge.

Conclusions

Patients with AS are highly susceptible to extensive neurological injury and spinal deformity after sustaining cervical fractures from even minor traumatic forces. These injuries are uniquely complex in nature and require considerable scrutiny and aggressive surgical management to optimize spinal stability and functional outcomes. The authors' clinical problem-solving algorithm will assist spine surgeons in providing optimal care in this difficult population.

Clinical outcomes of 90 isolated unilateral facet fractures, subluxations, and dislocations treated surgically and nonoperatively

STUDY DESIGN

A retrospective outcomes study.

OBJECTIVE

The purposes of this study were 1) to identify plausible patient and interventional variables that influence the outcome of unilateral facet injuries and 2) to determine if patients return to normal general health status after unilateral facet injuries.

SUMMARY OF BACKGROUND DATA

The management of unilateral subaxial cervical facet fractures and dislocations lacks agreement on treatment options and the variables that influence outcome.

METHODS

Injury data, radiographs, and outcomes (North American Spine Society Cervical Follow-up Questionnaire and Short Form-36) were collected from 9 centers and 13 surgeons, members of the Spine Trauma Study Group.

RESULTS

Causally motor vehicle accidents (49%) and sports (31%) predominated. The C6-C7 level accounted for 60% of injuries and C5-C6 represented 17%. The mean SF-36 PCS score of the operative patients with follow-up >18 months was 6.70 points higher than the mean of the nonoperative patients (P = 0.017). The SF-36 Bodily Pain mean of all patients was 67.2 (SD = 27.6), significantly lower (more pain) than the normative mean of 75.2 (SD = 23.7) (P = 0.014). Nonoperative patients also reported a mean Bodily Pain score of 63.0 (SD = 30.5) that was significantly worse than normative values (P = 0.031). Similarly, the NASS PD mean score for all patients was 84.8 (SD = 17.9), significantly lower than the normative mean of 89.1 (SD = 15.5) (P = 0.014).

CONCLUSION

To our knowledge this is the largest reported series of facet injuries to date and the only one using health-related quality of life instruments. Unilateral facet injuries of the subaxial cervical spine led to reported levels of pain and disability that are significantly worse than those of the healthy population. Although further study is required, we suggest that nonoperatively treated patients report worse outcomes than operatively treated patients, particularly at longer follow-up despite having a more benign fracture pattern. The presence of comorbidities, associated injuries, and advanced age adversely impact clinical outcomes.

The surgical approach to subaxial cervical spine injuries: an evidence-based algorithm based on the SLIC classification system

STUDY DESIGN

Systematic review of literature and expert clinical opinions of the members of the Spine Trauma Study Group were combined to develop and refine this algorithm.

OBJECTIVE

To develop an evidence-based algorithm for surgical approaches to manage subaxial cervical injuries using a systematic review of the literature, expert opinion, and anticipated patient preferences.

SUMMARY OF BACKGROUND DATA

There is lack of consensus in the management of subaxial cervical spine trauma, in part, because of the lack of a clinically relevant system for classifying these injuries. The newly developed Subaxial Injury Classification scoring system categorizes injury morphology into 3 broad groups, includes an assessment of the integrity of the discoligamentous soft tissue structures and the patient's neurologic status, and thus guides surgical or nonsurgical treatment. The choice of a specific surgical technique and approach is currently not evidence based, and this gap in knowledge is one which the current article seeks to address.

METHODS

A literature review followed by a consensus of experts approach was used to develop the algorithm and to ensure face and content validity.

RESULTS

An algorithm is presented to guide the choice of surgical approach in cervical subaxial burst fractures, distraction injuries, and translation or rotation injuries. The burst or compression injuries and distraction injuries are more likely to be treated with a single anterior approach, whereas the more severe translation or rotation injuries may more commonly be approached posteriorly or with combined anterior and posterior surgery.

CONCLUSION

This algorithm; derived from the Subaxial Injury Classification scoring system, will assist surgeons in answering the 2 most common questions they face when managing subaxial cervical spine trauma: "Should I operate?" and "Which surgical approach should I select?"

Early results from posterior cervical fusion with a screw-rod system

PURPOSE

We performed 65 cases of posterior fusion surgery for cervical and/or high thoracic lesions using a polyaxial screw-rod system.

PATIENTS AND METHODS

A total of 486 screws were implanted in 65 patients.

RESULTS

Fixation of the screws was carried out over an average of 2.9 spinal segments. Upon evaluation by postoperative CT scans, twelve (2.5%) screws had suboptimal trajectories but two of these revealed radiculopathy in one patient and required screw repositioning. No vascular sequelae resulted. There has been no segmental motion in any of the cases to date. As for other complications, there was one case of dural tearing and two cases of lateral mass fractures. There were no infections or other wound healing problems or hardware failures. No patients had neurological deterioration after surgery. There were statistically significant improvements in the mean Neck Disability Index (NDI) scores and Visual Analogue Scale (VAS) scores in the preoperative and late postoperative follow-up evaluations. Although further studies are required to establish the long-term results of fusion rates and clinical outcomes.

CONCLUSION

We cautiously suggest that the posterior polyaxial screw-rod system can be safely used as a primary or additional fusion method in this risky region. The successful and safe use of this method is dependent on a precise preoperative surgical plan and tactics for ensuring safe screw fixation.

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

Although many different techniques exist for fusion of midcervical facet fracture dislocations, limiting arthrodesis to a single level could have a theoretical advantage: fewer fused segments could lessen long-term negative effects of fusion on adjacent segments. Therefore, we prospectively treated 22 consecutive patients with midcervical fracture dislocation without vertebral body fracture with single level arthrodesis even if anterior/posterior surgery were required. Twelve patients with unilateral facet subluxation underwent anterior cervical discectomy, distraction reduction with Caspar posts (AESCULAP, Tuttlingen, Germany) with allograft fusion and anterior cervical plating. Ten patients with any component of bilateral facet subluxation underwent anterior cervical discectomy, distraction reduction with Caspar posts, allograft fusion and plating followed by posterior lateral mass plating. No patients demonstrated worsening of nerve root or spinal cord function postoperatively. Interbody stability occurred in all cases. Only complications were 4 cases of pneumonia, 1 case of wound leakage, and 1 case of superficial wound infection. Good reduction was achieved for both unilateral and bilateral facet fractures. Single level interbody arthrodesis is safe and effective strategy with both unilateral and bilateral facet fractures. Single level arthrodesis may also offer long-term benefit compared with multilevel fusions.

A Mechanical Study of Rigid Plate Configurations for Sternal Fixation

Rigid metal plates are a promising alternative to wires for reapproximating the sternum after open-heart surgery due to their potential ability to reduce motion at the wound site and thereby reduce the likelihood of post-operative healing complications. Despite initial clinical success, the use of plates has been limited, in part, by insufficient knowledge about their most effective placement. This study compares the ability of five plate configurations to provide stable closure by limiting sternal separation. Commercially available x-shaped and box-shaped plates were used and combinations of parameters (plate type, location, and number of plates) were investigated in vitro. Lateral distraction tests using controlled, uniform loading were conducted on 15 synthetic sterna and the distractions between separated sternum halves were measured at seven locations. Distractions at the xiphoid, a critical region clinically, varied widely from 0.03 +/- 0.53 mm to 4.24 +/- 1.26 mm depending on all three plate parameters. Of the configurations tested, three x-shaped plates and one box-shaped plate resisted sternal separation most effectively. These results provide the first comparison of plate configurations for stabilizing a sternotomy. However, basic mechanical analyses indicate that sternal loading in vivo is non-uniform; future studies will need to accurately quantify in vivo loading to improve in vitro test methods.

Estudo experimental da resistência das osteossínteses com placas e parafusos na fixação anterior da coluna cervical

Com o objetivo de verificar a resistência das osteossínteses com placas e parafusos, por via anterior, o autor realizou estudo experimental em segmentos da coluna cervical (C3-C7) de cadáveres frescos, comparando três diferentes tipos de placas. Utilizou placa tipo H de Orozco (4 peças), placa convencional de 1/3 de tubo (4 peças), placa de Mendonça (5 peças) e o Grupo Controle sem osteossíntese (5 peças). Em todas as 18 peças foi realizado corpectomia central sem destruição das paredes laterais do corpo vertebral. As peças foram testadas em máquina de compressão axial, com registrador gráfico mecânico, sendo aplicadas cargas lentas e progressivas. Os resultados mostraram, em relação à falha inicial, que as estabilizações das osteossínteses são semelhantes entre elas, mas inferiores ao Grupo Controle. Estatisticamente não é significativa a diferença de estabilidade entre o Grupo com a placa H e o Grupo Controle, entretanto existe diferença entre este e os grupos com as placas de 1/3 de tubo e de Mendonça. Em relação à resistência máxima, não houve diferença significativa na comparação entre as osteossínteses e entre estas o Grupo Controle. Com base nos resultados, o autor conclui que a osteossíntese com placa H confere maior estabilidade quando comparada às outras osteossínteses, porém as placas e parafusos utilizados diminuíram a estabilidade, determinando que a falha inicial ocorresse precocemente, quando comparada ao Grupo Controle.

DORSAL SURGERY FOR MYELOPATHY AND MYELORADICULOPATHY

OBJECTIVE

To review the dorsal approaches to the cervical spine for myelopathy and myeloradiculopathy.

METHODS

The literature was reviewed in reference to dorsal approaches for cervical myelopathy and myeloradiculopathy.

RESULTS

There are a variety of surgical approaches in the management of cervical myelopathy and myeloradiculopathy. Deciding which is the best method for any individual requires the surgeon to be aware of the advantages of each technique, as well as the complications and limitations of each approach.

CONCLUSION

Laminectomy is the traditional technique used for multilevel cervical stenosis. The complications related to laminectomy, such as late neurological decline, kyphosis, instability, and postoperative radiculopathy, led to laminectomy with fusion. In Japan, dissatisfaction with both laminectomy and laminectomy with fusion led to the development of laminoplasty for dorsal treatment of multilevel cervical stenosis. This article highlights the salient features of preoperative evaluation in this patient population as it pertains to dorsal surgical approaches. Additionally, the techniques of laminectomy, laminectomy with fusion, and laminoplasty are compared, and the results are reviewed.

Early complications of posterior rod-screw fixation of the cervical and upper thoracic spine

OBJECTIVE

The technique of rod-screw fixation of the cervical spine is well described. However, there is very little data on the complications incurred by the application of these devices. The purpose of this study was to quantify the risks associated with rod fixation of the cervical spine.

METHODS

A prospective study was performed on 100 consecutive patients treated with this technique. Clinical and radiographic assessment was performed immediately after surgery 3, 6, and 12 months postoperatively, and annually thereafter. The mean follow-up interval was 16.7 months.

RESULTS

A total of 888 screws were implanted in 100 patients. Perioperative complications included radiculopathy (n = 4, 0.45% per screw placed), infection and other wound-healing problems (n = 4), screw malposition (n = 2), loss of alignment (n = 1), and cerebrospinal fluid leak (n = 1). There were no examples of spinal cord or vertebral artery injury. Early complications (within 6 mo of surgery) included pseudarthrosis (n = 2) and screw breakage (n = 2, 0.22% per screw placed). There were no late complications. Reoperation was required in eight cases, all within 6 months of the index procedure. Indications for reoperation included wound-healing problems (n = 4), malpositioned screw (n = 2), and pseudarthrosis (n = 2). No patient required another operation for any indication beyond the 6-month postoperative interval.

CONCLUSION

Rod-screw fixation was an effective method of posterior cervical stabilization that could be safely applied in a wide range of spinal disorders. In a complex group of patients, the complication rates were modest, and compared favorably with other methods of fixation.

Minimally Invasive Posterior Cervical Arthrodesis and Fixation

This article describes the use of minimally invasive posterior cervical arthrodesis and internal fixation for the subaxial cervical spine. Such systems vary by the angulation of their screws and in the degree of the constraint placed at the screw-rod interface. The polyaxial tulip or islet connectors of the screws are able to angle medially, laterally, and straight, with varying degrees of rotational freedom in each direction, thus making segmental fixation more easily achievable from a top-loading approach and allowing for the possibility of minimally invasive posterior cervical fixation.

In vitro comparison of wire and plate fixation for midline sternotomies

BACKGROUND

The incidence of severe sternal wound complications in high-risk cardiac patients presents a significant need for more stabile sternal fixation techniques after median sternotomy procedures. Rigid metal plates, a potential alternative to wire fixation, are thought to promote faster sternal healing by reducing motion at the wound site. The goal of this study was to compare the stability provided by commercially available sternal plates with standard wires using an in vitro model.

METHODS

Lateral distraction tests were conducted on bisected polyurethane sternal models fixed with either a standard 7 wire configuration (n = 5) or a 3 plate configuration (n = 3). To assure controlled loading, the sternal models were attached to a computer-controlled test machine by a novel tethering system that distributes the total force (180N) equally to eight locations on the sternum. Stability was defined as the ability to restrict sternal separation at seven locations along the midline quantified using digital image analysis.

RESULTS

Our results indicate that rigid plate fixation significantly reduced lateral motion relative to wire fixation. The lower sternal region most noticeably benefited from plate fixation as the splaying observed for wire fixation was reduced.

CONCLUSIONS

Under these loading conditions, plating increased stability at the midline compared to wires; this increased stability may facilitate the recovery of high-risk patients undergoing cardiac operation. To enhance in vitro testing methods, future studies should incorporate additional in vivo loading conditions applied to the sternum. Alternate plating configurations should also be examined to further increase stability.

Poor surgical technique in cervical plating leading to vertebral artery injury and brain stem infarction—case report

BACKGROUND

Lateral mass plating is a safe fixating system for lower cervical fractures. Brain stem infarction after cervical lateral mass screw plating has not been reported in previous literature. We report a case of poor surgical technique leading to vertebral artery injury and brain stem infarction after cervical lateral mass plating.

CASE DESCRIPTION

A 41-year-old male patient was transferred to our hospital because of hemiparesis and dysarthria immediately after lateral mass plating for fracture and dislocation of the fifth and sixth cervical vertebrae. Brain magnetic resonance imaging showed infarction of the left posterior inferior cerebellar artery territory, and the vertebral artery angiography showed complete occlusion of the left vertebral artery. The cervical computed tomography revealed a left screw of the fifth and sixth cervical vertebrae penetrating the central portion of the transverse foramen. The patient was managed with anticoagulant and supportive therapy only, with subsequent improvement of hemiparesis and dysarthria.

CONCLUSIONS

Poor surgical technique of lateral mass plating in the cervical spine could lead to vertebral artery injury and even brain stem infarction. Postoperative brain infarction in cervical fusion could be a complication of the usually safe lateral mass plating of the cervical spine.

Posterior fixation of subaxial cervical spine fractures in patients with ankylosing spondylitis

Cervical spine fractures in patients with ankylosing spondylitis are serious and potentially lethal injuries with high complication rates. Treatment obstacles include long lever arms that generate large forces on any fixation device, osteoporosis, and, usually, kyphotic deformity. The Olerud Cervical Fixation System (OC), with cervical pedicle screws and rods, offers an opportunity to create a biomechanically stable posterior fixation in these complicated cases. The present study is a retrospective chart review and a radiological follow-up of patients with this diagnosis, treated at our department between 1995 and 2000. Nineteen patients (two women) with a mean age of 60 years (32-78 years) were included. The fracture levels were predominantly C5-C6 (five patients) and C6-C7 (five patients). All patients were treated with a long posterior fixation with the OC, and in four patients this was combined with an anterior plate fixation. One patient with severe lordosis also received a short posterior plate fixation. The patients' notes and plain radiographs have been reviewed. Five patients died during the post-operative follow-up period; the others had a mean follow-up time of 24 months (10-55 months). Eleven patients had no neurological deficits preoperatively. One of them developed moderate weakness in his right arm, postoperatively, due to a misplaced pedicle screw in the right pedicle of C5. However, after extraction of the screw he almost totally recovered in 6 months. Eight patients had neurological deficits. Two were paraplegic; two had motor weakness combined with sensory deficiency, and four had a sensory deficiency. Two of the patients with neurological deficits improved postoperatively, but the others were unchanged. Peroperative problems were recorded in five patients; one C6 pedicle was perforated, and two patients had pedicles on one or more levels that the surgeon was not able to probe. In one of the latter patients, transfacet screws were chosen, instead, for one of the levels. Extensive peroperative bleeding was encountered in two patients. One deep-wound infection was noted, postoperatively, and required surgical drainage, but no patients have been re-operated due to loosening of the instrument or to healing problems. In conclusion, the results of the present study indicate that the OC--and possibly other similar long-fixation systems that allow using both pedicle screws and lateral mass screws rigidly connected to a rod--is suited for treating subaxial cervical spine fractures in patients with ankylosing spondylitis, allowing high healing rates.

Quantitative anatomic evaluation of cervical lateral mass fixation with a comparison of the Roy-Camille and the Magerl screw techniques

STUDY DESIGN

An anatomic and computed tomography (CT) study of the Roy-Camille and the Magerl techniques with quantitative comparison of the safety zones of the two surgical techniques.

OBJECT

The purpose of this study was to compare quantitatively the safety zones of the Roy-Camille and the Magerl techniques as a function of the vertebral level from C3-C6.

SUMMARY OF BACKGROUND DATA

The two most popular techniques for lateral mass screws are the Roy-Camille and the Magerl technique. Nerve roots, vertebral artery, facet joints, and the spinal cord are at risk during the placement of lateral mass screws. Several anatomic studies are reported, but there is no comparative and quantitative evaluation. The influence of the vertebral level was never reported.

METHODS

Lateral mass screws were first implanted on four cervical spines according to the two surgical techniques. Screws were then extracted and their cavities filled with a blue casting medium. To determine the precise limits of each safety zone in the sagittal plane, the specimens were sectioned according to the sagittal angulation of the two screwing techniques. The correlations between the anatomic landmarks on the specimen and the anatomic landmarks on the CT scan were established. One hundred and sixty lateral mass screws were then implanted in 20 cervical spines from C3-C6. A CT was done before and after placing lateral mass screws. On the morphologic CT scan, we measured the sagittal safety angle (SSA) for each surgical technique and also performed a morphometry of lateral masses. On the control CT scan, we analyzed screws placement in relation to the sagittal safety zone.

RESULTS

The mean SSA was 15.8 +/- 6.3 degrees for the Roy-Camille technique and 18.7 +/- 3.8 degrees for the Magerl technique, P < 0.005. With respect to the vertebral level, the Roy-Camille safety zone decreased from C3-C6 with a greater angulation at C3-C4 (20.4 +/- 4.7 degrees ) than at C5-C6 (11.6 +/- 4.3 degrees ), P < 0.001. Such variations were not observed for the Magerl technique, the SSA of which was 19.4 +/- 3.6 degrees at C5-C6 and 17.9 +/- 4 degrees at C3-C4, P < 0.01. Lateral masses became more elongated and thinner at the lower segment of the cervical spine with a C3-C4 height/thickness ratio = 1.1 +/- 0.3 and a C5-C6 height/thickness ratio = 1.3 +/- 0.2, P < 0.005. Roy-Camille screws (19%) were found out of the safety zone at C3-C4 whereas 37.5% were found outside at C5-C6, P < 0.05. We observed opposite results for Magerl screws with 38% screws out of the safety zone at C3-C4 and only 17.5% outside at C5-C6, P < 0.05.

CONCLUSION

The Roy-Camille technique demonstrated a progressive decrease of its safety zone from C3-C6. At C5 and C6 there is a great probability to have a transarticular screw with a Roy-Camille screw. A similar variation was not observed for the Magerl technique. These anatomic results seem to be in relation with the morphologic variability of lateral masses from C3-C6 as demonstrated by an increase of the height/thickness ratio at the lower part of the cervical spine. According to these anatomic considerations and previously published biomechanical data, Roy-Camille technique appears to be the best option at C3 and C4. On the opposite at C5 and C6, the choice is more difficult considering that there is no biomechanical difference between the two techniques and that the Magerl technique is safer but a more demanding procedure.

Cervical spine injuries associated with lateral mass and facet joint fractures: new classification and surgical treatment with pedicle screw fixation

To clarify the injury pattern, initial spinal instability, degree of discoligamentous injuries in cervical lateral mass and facet joint fractures, we retrospectively analyzed radiological parameters and introduced a new classification for these injuries. Surgical treatment was performed with cervical pedicle screw fixation (CPS), and overall neurological and radiological outcome was evaluated with a minimum follow-up period of 2 years. Lateral mass fractures were divided into the following four subtypes: separation, comminution, split, and traumatic spondylolysis. The sagittal and frontal alignments were evaluated at both mainly injured and adjacent spinal segments on radiographs. The initial discoligamentous injuries were investigated on magnetic resonance imaging in terms of their frequencies, subtype of injuries, and involved spinal levels. Anterior translation of fractured vertebra was demonstrated in 77% of lateral mass fractures, while 24% of anterior translation was observed, even in cephalad-adjacent vertebrae. On magnetic resonance imaging, signal changes in anterior longitudinal ligament (ALL) and intervertebral disc were demonstrated in 76% of caudal segments and 24% of cephalad segments adjacent to fractured vertebra of lateral mass fractures. The subtype analyses of lateral mass fractures demonstrated high rates of anterior translation in separation, split, and traumatic spondylolisthesis, as well as significant coronal malalignment in comminution and split types (p<0.05). Thirty-one patients underwent surgical treatments using a cervical pedicle screw fixation. The CPS provided the superior capability of deformity correction without pseudoarthrosis, as well as excellent neurological recovery. The average numbers of stabilized segments were minimized without serious complications. In separation, facet joint fracture, and fractures with mild lateral mass comminution, the single level posterior fixation can be considered. The significant unstable injuries of split and comminution type with coronal malalignment can be treated with exclusive two-level posterior stabilization with CPS. The initial evaluation of fracture subtypes helps to successfully minimize the stabilized spinal segment.

The radiographic failure of single segment anterior cervical plate fixation in traumatic cervical flexion distraction injuries

STUDY DESIGN

A radiographic review of 87 patients with either unilateral or bilateral facet dislocations or fracture/dislocations treated with anterior cervical discectomy, fusion, and plating.

OBJECTIVE

The primary objective of this study was to report the incidence of radiographic failure and factors that would predispose to this loss of alignment. The secondary objective was to report the rate of pseudarthrosis.

SUMMARY OF BACKGROUND DATA

Biomechanical and clinical data conflict regarding the appropriate approach and method of fixation of distractive flexion cervical injuries. Unilateral and bilateral facet fracture subluxations may be surgically stabilized by anterior cervical discectomy, fusion, and plating, posterior instrumentation, or both. There are no documented reports of the rate of radiographic failure of this procedure when limited to a single level injury from a distractive flexion mechanism.

METHODS

Inclusion criteria were all single-level unilateral and bilateral facet fracture dislocations or subluxations treated with a single-level anterior cervical discectomy, fusion, and plating. Retrospectively, 107 cases were identified (87 with complete radiographs) from January 1994 to December 2001. Radiographic failure was defined as a change in translation of greater than 4 mm and/or change in angulation of greater than 11 degrees between the immediate postoperative films and the most recent follow-up. Fusion was assessed radiographically.

RESULTS

A 13% incidence of radiographic loss of alignment is reported in 87 unilateral and bilateral facet fracture subluxations stabilized with anterior cervical discectomy, fusion, and plating. Radiographic failure correlated with the presence of endplate compression fracture and facet fractures on injury radiographs. There was no correlation between radiographic failure and age, gender, surgeon, unilateral or bilateral injury, plate type, level of injury, degree of translation, or sagittal alignment at the time of injury.

CONCLUSION

Loss of postoperative alignment occurred in 13% of facet fracture subluxations treated with anterior cervical discectomy, fusion, and plating. Concern regarding mechanical failure of flexion/distraction injuries should be high when they are associated with fractures of either the facets or of the endplate. Endplate fracture was associated with both mechanical failure and pseudarthrosis.

Factors associated with good outcome using lateral mass plate fixation

The immediate and long-term outcomes of 70 consecutive patients who underwent subaxial lateral mass fixation between June 1996 and June 2001 were reviewed. Intraoperative fluoroscopy and somatosensory evoked potential (SEP) monitoring were used in all patients. Immediate postoperative computed tomography (CT) was performed to determine screw trajectory and placement. Follow-up ranged from 2 to 7 years. Postoperative CT showed 206 (58%) of 356 screws had unicorticate and 42% bicorticate purchase. Furthermore, 96 (27%) screws had suboptimal trajectory, but only 5 of these screws minimally penetrated the foramen transversarium without resultant vascular or neurological sequelae. A sudden unilateral intraoperative SEP amplitude decrease during screw placement in 2 patients resolved with screw removal and alteration of screw trajectory. The overall fusion success rate was 91.5% and screw pull-out developed in 2 patients. The recommended drilling technique and trajectory (15 degrees - 25 degrees rostral in the sagittal plane, 20 degrees - 30 degrees lateral in the axial plane), supplemented bone grafting, and intraoperative SEP monitoring are all associated with good screw placement, fusion, and neurological outcome and are recommended for all lateral mass fusion procedures.

Medical Devices of the Head, Neck, and Spine

There are many medical devices used for head, neck, and spinal diseases and injuries, and new devices are constantly being introduced. Many of the newest devices are variations on a previous theme. Knowing the specific name of a device is not important. It is important to recognize the presence of a device and to have an understanding of its function as well as to be able to recognize the complications associated with its use. The article discusses the most common and important devices of the head, neck, and spine, including cerebrospinal fluid shunts and the Codman Hakim programmable valve; subdural drainage catheters, subdural electrodes, intracranial electrodes, deep brain stimulators, and cerebellar electrodes; coils, balloons, adhesives, particles, and aneurysm clips; radiation therapy catheters, intracranial balloons for drug installation, and carmustine wafers; hearing aids, cochlear implants, and ossicular reconstruction prostheses; orbital prostheses, intraocular silicone oil, and lacrimal duct stents; anterior and posterior cervical plates, posterior cervical spine wiring, odontoid fracture fixation devices, cervical collars and halo vests; thoracic and lumbar spine implants, anterior and posterior instrumentation for the thoracic and lumbar spine, vertebroplasty, and artificial disks; spinal column stimulators, bone stimulators, intrathecal drug delivery pumps, and sacral stimulators; dental and facial implant devices; gastric and tracheal tubes; vagus nerve stimulators; lumboperitoneal shunts; and temperature- and oxygen-sensing probes.

Combined laminoplasty with posterior lateral mass plate for unstable spondylotic cervical canal stenosis--technical note

A technique of combined expanding laminoplasty using longitudinal interspinous iliac bone graft with posterior lateral mass plate is described for the treatment of cervical canal stenosis associated with spinal instability. A 52-year-old male and a 76-year-old female presented with cervical myelopathy. Imaging studies demonstrated spondylotic cervical canal stenosis associated with spinal instability. Posterior stabilization with lateral mass plate by the Axis Fixation System was performed after expanding laminoplasty using interspinous iliac bone graft. The symptoms improved and instability and malalignment (in the female patient) also improved after surgery. This combined surgical technique allows decompression of the spinal cord, immediate internal fixation by plate fixation, and subsequent long-term stabilization by interspinous bony fusion. This technique is indicated in selected patients with multiple segment spondylotic cervical canal stenosis associated with instability and/or malalignment of the spinal column for which simultaneous decompression and stabilization are required.

Laminectomy and Posterior Cervical Plating for Multilevel Cervical Spondylotic Myelopathy and Ossification of the Posterior Longitudinal Ligament: Effects on Cervical Alignment, Spinal Cord Compression, and Neurological Outcome

OBJECTIVE

Multilevel anterior decompressive procedures for cervical spondylotic myelopathy or ossification of the posterior longitudinal ligament may be associated with a high incidence of neurological morbidity, construct failure, and pseudoarthrosis. We theorized that laminectomy and stabilization of the cervical spine with lateral mass plates would obviate the disadvantages of anterior decompression, prevent the development of kyphotic deformity frequently seen after uninstrumented laminectomy, decompress the spinal cord, and produce neurological results equal or superior to those achieved by multilevel anterior procedures.

METHODS

We retrospectively reviewed the records of 38 patients who underwent laminectomy and lateral mass plating for cervical spondylotic myelopathy or ossification of the posterior longitudinal ligament between January 1994 and November 2001. Seventy-six percent of patients had spondylosis, 18% had ossification of the posterior longitudinal ligament, and 5% had both. Clinical presentation included upper extremity sensory complaints (89%), gait difficulty (70%), and hand use deterioration (67%). Spasticity was present in 83%, and weakness of one or more muscle groups was seen in 79%. Spinal cord signal abnormality on sagittal T2-weighted magnetic resonance imaging (MRI) was seen in 68%. Neurological evaluation was performed using a modification of the Japanese Orthopedic Association Scale for functional assessment of myelopathy, the Cooper Scale for separate evaluation of upper and lower extremity motor function, and a five-point scale for evaluation of strength in individual muscle groups. Lateral cervical spine x-rays were analyzed using a curvature index to determine maintenance of alignment. Each surgically decompressed level was graded on a four-point scale using axial MRI to assess the adequacy of decompression. Late follow-up was conducted by telephone interview.

RESULTS

Laminectomy was performed at a mean 4.6 levels. Follow-up was obtained at a mean of 30.2 months after the procedure. The score on the modified Japanese Orthopedic Association scale improved in 97% of patients from a mean of 12.9 preoperatively to 15.58 postoperatively (P&lt; 0.0001). In the upper extremities, function measured by the Cooper Scale improved from 1.8 to 0.7 (P&lt; 0.0001), and in the lower extremities, function improved from 1.0 to 0.4 (P&lt; 0.0002). There was a statistically significant improvement in strength in the triceps (P&lt; 0.0001), iliopsoas (P&lt; 0.0002), and hand intrinsic muscles (P&lt; 0.0001). X-rays obtained at a mean of 5.9 months after surgery revealed no change in spinal alignment as measured by the curvature index. There was a decrease in the mean preoperative compression grade from 2.46 preoperatively to 0.16 postoperatively (P&lt; 0.0001). There was no correlation between neurological outcome and the presence of spinal cord signal change on T2-weighted MRI scans, patient age, duration of symptoms, or preoperative medical comorbidity.

CONCLUSION

Multilevel laminectomy and instrumentation with lateral mass plates is associated with minimal morbidity, provides excellent decompression of the spinal cord (as visualized on MRI), produces immediate stability of the cervical spine, prevents kyphotic deformity, and precludes further development of spondylosis at fused levels. Neurological outcome is equal or superior to multilevel anterior procedures and prevents spinal deformity associated with laminoplasty or noninstrumented laminectomy.