Magnetic resonance imaging analysis of soft tissue disruption after flexion-distraction injuries of the subaxial cervical spine

Open Reduction in Traumatic Cervical Facet Dislocation Does Not Delay Time to Treatment

Background Cervical facet dislocation is a serious injury that can result in permanent neurologic damage. Current guidelines recommend immediate closed reduction of cervical dislocations, though the efficacy of this practice remains a debate. This study aims to evaluate whether immediate open reduction and fixation of cervical dislocations offer equal or better outcomes for patients and limit the need for follow-up operations. Methods This is a retrospective study including patients who presented to the emergency department of a single institution from 2008 to 2023 with cervical facet dislocation. Patients were divided into groups based on initial treatment: either open or closed reduction. Time to surgery was calculated as the time between arrival to the ED and incision time in the OR. Primary outcomes were improvement in motor and sensory deficits at six-week post-operative follow-up. Results There were 31 patients who met the inclusion criteria. Time to treatment did not differ significantly between the open versus closed reduction groups. There were no differences between groups in improvement in motor function, sensory function, or pain at the six-week follow-up. All patients treated with initial closed reduction ultimately required surgical stabilization. Conclusions Open reduction as a first-line treatment did not increase the time to treatment for patients with cervical facet dislocations. Patients had equivalent functional outcomes in both treatment groups. The findings suggest that current practice guidelines may delay definitive treatment without improving patient safety or outcomes.

Management of Cervical Spinal Cord Injury without Major Bone Injury in Adults

The incidence of cervical spinal cord injury (CSCI) without major bone injury is increasing, possibly because older people typically have pre-existing cervical spinal canal stenosis. The demographics, neurological injury, treatment, and prognosis of this type of CSCI differ from those of CSCI with bone or central cord injury. Spine surgeons worldwide are debating on the optimal management of CSCI without major bone injury. Therefore, this narrative review aimed to address unresolved clinical questions related to CSCI without major bone injury and discuss treatment strategies based on current findings. The greatest divide among spine surgeons worldwide hinges on whether surgery is necessary for patients with CSCI without major bone injury. Certain studies have recommended early surgery within 24 h after injury; however, evidence regarding its superiority over conservative treatment remains limited. Delayed MRI may be beneficial; nevertheless, reliable factors and imaging findings that predict functional prognosis during the acute phase and ascertain the necessity of surgery should be identified to determine whether surgery/early surgery is better than conservative therapy/delayed surgery. Quality-of-life assessments, including neuropathic pain, spasticity, manual dexterity, and motor function, should be performed to examine the superiority of surgery/early surgery to conservative therapy/delayed surgery.

Immediate Closed Reduction Technique for Cervical Spine Dislocations

STUDY DESIGN

Retrospective study.

PURPOSE

This research aimed to assess the clinical outcomes of patients with traumatic cervical spine dislocation who underwent closed reduction employing our approach.

OVERVIEW OF LITERATURE

Bedside closed reduction is the quickest procedure for repairing traumatic cervical spine dislocations; nevertheless, it also possesses the risk of neurological deterioration.

METHODS

For closed reduction, the patient's head was elevated on a motorized bed, the cervical spine was placed at the midline, traction of 10 kg was applied, the motorized bed was gradually returned to a flat position, the head was lifted off the bed, and the cervical spine was slowly adjusted to a flexed position. The weight of traction was elevated by 5-kg increments until the positional shift was attained. Subsequently, the bed was gradually tilted while traction was applied again to return the cervical spine to the midline position.

RESULTS

Of the 43 cases of cervical spine dislocation, closed reduction was carried out in 40 cases, of which 36 were successful. During repositioning, three patients experienced a temporary worsening of their neck pain and neurological symptoms that enhanced when the cervical spine was flexed. Closed reduction was conducted while the patient was awake; nevertheless, sedation was needed in three cases. Among the 24 patients whose pretreatment paralysis had been characterized by American Spinal Injury Association Impairment Scale (AIS) grades A-C, seven patients (29.2%) demonstrated an enhancement of two or more AIS grades at the last observation.

CONCLUSIONS

Our closed reduction approach safely repaired traumatic cervical spine dislocations.

Traumatic irreducible non-Hangman's type bilateral C2-C3 high-grade facet dislocation: technical nuance

Majority of C2-C3 vertebral dislocations occur as in combination with bilateral pars fractures, also known as Hangman's fractures. Isolated C2-C3 facet dislocation without any associated C2 fracture is a very rare injury. One such case has been presented in this report. A 29-year male was involved in a road traffic accident (RTA) after which he developed midline neck pain. Following a minor neck manipulation at a hair salon 15 days after the RTA, his neck pain worsened and he developed quadriparesis. Imaging at the time of admission showed bilateral high-grade C2-C3 facet dislocations without any associated fracture of C2 vertebra. Due to non-reduction of the dislocation with skeletal traction, surgery was contemplated. Intraoperatively, the C2-C3 joint spaces were opened but only partial reduction could be achieved. Complete reduction was achieved only after opening of the C1-C2 joints was performed. Later, C2-C4 screw-rod constructs were placed. Patient achieved good outcome with resolution of symptoms. This report concludes that, in cases of delayed presentation of irreducible C2-C3 bilateral facet dislocations and non-reducibility by skeletal traction, opening of the C1-2 joints may need to be performed in addition to the C2-C3 joint spaces, in order to achieve complete reduction.

Role of magnetic resonance imaging features in diagnosing and localization of disc rupture related to cervical spinal cord injury without radiographic abnormalities

STUDY DESIGN

A retrospective study.

OBJECTIVE

Traumatic cervical spinal cord injury (TSCI) is often associated with disc rupture. It was reported that high signal of disc and anterior longitudinal ligament (ALL) rupture on magnetic resonance imaging (MRI) were the typical signs of ruptured disc. However, for TSCI with no fracture or dislocation, there is still difficult to diagnose disc rupture. The purpose of this study was to investigate the diagnostic efficiency and localization method of different MRI features for cervical disc rupture in patient with TSCI but no any signs of fracture or dislocation.

SETTING

Affiliated hospital of University in Nanchang, China.

METHODS

Patients who had TSCI and underwent anterior cervical surgery between June 2016 and December 2021 in our hospital were included. All patients received X-ray, CT scan, and MRI examinations before surgery. MRI findings such as prevertebral hematoma, high-signal SCI, high-signal posterior ligamentous complex (PLC), were recorded. The correlation between preoperative MRI features and intraoperative findings was analyzed. Also, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of these MRI features in diagnosing the disc rupture were calculated.

RESULTS

A total of 140 consecutive patients, 120 males and 20 females with an average age of 53 years were included in this study. Of these patients, 98 (134 cervical discs) were intraoperatively confirmed with cervical disc rupture, but 59.1% (58 patients) of them had no definite evidence of an injured disc on preoperative MRI (high-signal disc or ALL rupture signal). For these patients, the high-signal PLC on preoperative MRI had the highest diagnostic rate for disc rupture based on intraoperative findings, with a sensitivity of 97%, specificity of 72%, PPV of 84% and NPV of 93%. Combined high-signal SCI with high-signal PLC had higher specificity (97%) and PPV (98%), and a lower FPR (3%) and FNR (9%) for the diagnosis of disc rupture. And combination of three MRI features (prevertebral hematoma, high-signal SCI and PLC) had the highest accuracy in diagnosing traumatic disc rupture. For the localization of the ruptured disc, the level of the high-signal SCI had the highest consistency with the segment of the ruptured disc.

CONCLUSION

MRI features, such as prevertebral hematoma, high-signal SCI and PLC, demonstrated high sensitivities for diagnosing cervical disc rupture. High-signal SCI on preoperative MRI could be used to locate the segment of ruptured disc.

The Effect of Anterior-Only, Posterior-Only, and Combined Anterior Posterior Fixation for Cervical Spine Injury with Soft Tissue Injury: A Finite Element Analysis

OBJECTIVE

This finite element analysis aimed to investigate the effects of surgical procedures for cervical spine injury.

METHODS

A three-dimensional finite element model of the cervical spine (C2-C7) was created from computed tomography. This model contained vertebrae, intervertebral discs, anterior longitudinal ligament, and posterior ligament complex. To create the cervical spine injury model, posterior ligament complex and anterior longitudinal ligament at C3-C4 were resected and the center of the intervertebral disc was resected. We created posterior-only fixation (PF), anterior-only fixation (AF), and combined anterior-posterior fixation (APF) models. A pure moment with a compressive follower load was applied, and range of motion, annular/nucleus stress, instrument stress, and facet forces were analyzed.

RESULTS

In all motion except for flexion, range of motion of PF, AF, and APF models decreased by 80%-95%, 85%-93%, and 97%-99% compared with the intact model. C3-C4 annulus stress of PF, AF, and APF models decreased by 28%-72%, 96%-100%, and 99%-100% compared with the intact model. Facet contact forces of PF, AF, and APF models decreased by 77%-79%, 97%-99%, and 77%-86% at C3-C4 compared with the intact model. Screw stress in the PF model was higher than in the APF model, and plate stress in the AF model was lower than in the APF model, but bone graft stress in the AF model was higher than in the APF model.

CONCLUSIONS

Cervical stabilization was preserved by the APF model. Regarding range of motion, the PF model had an advantage compared with the AF model except for flexion. An understanding of biomechanics provides useful information for the clinician.

The impact of traumatic herniated discs in cervical facets dislocations treatments: systematic review and meta-analysis

BACKGROUND

Traumatic facet dislocations in the subaxial cervical spine, also known as locked facets, are commonly associated with neurological deficits. The fear of the presence of an associated traumatic disc herniation and consequent neurological worsening usually causes a delay in the spinal realignment. This study's aim is an analysis of safety and efficacy when treating acute cervical traumatic facet dislocations using cranial-cervical traction or posterior open reduction and fixation in the presence of disc herniations.

METHODS

Inclusion criteria addressed the following patient groups: (1) MRI diagnosis of traumatic cervical facet dislocations with disc herniation, (2) intervention: either cranial-cervical traction or posterior open reduction and fixation, (4) neurological outcomes after treatment, (5) adult 18 plus years of age, (6) sample sizes greater than 20 patients, (7) English language publication. The following databases and search tools were analyzed: MEDLINE (PubMed), Cochrane Central Register of Controlled Trials (CENTRAL), Google Scholar, and the clinical trial registries (ClinicalTrials.gov), October 2021.

RESULTS

Six studies were found, 2 with posterior open reduction and fixation and 4 with cranial-cervical traction, totalizing 197 patients. Neurological worsening was reported only in 1 case (0.5%).

CONCLUSIONS

Traumatic disc herniation in cervical facet dislocations is not an absolute contraindication of cranial-cervical traction or posterior open reduction. Early realignment of the spine could bring more neurological benefits than waiting for an MRI or surgical discectomy. However, caution is needed in this review's data interpretation until prospective and well-designed studies are performed.

Conundrum in surgical management of three-column injuries in sub-axial cervical spine: a systematic review and meta-analysis

STUDY DESIGN

Systematic Review and Meta-analysis.

PURPOSE

Three-column injuries making the spine unstable require adequate fixation which can be achieved by anterior alone, posterior alone or combined anterior-posterior approach. There is no general consensus till date on a single best approach in sub-axial cervical spine trauma. This study comparing the three approaches is an attempt to establish a firmer guideline in this disputed topic.

MATERIAL AND METHODS

The protocol was registered with PROSPERO. PubMed, Embase and Google Scholar were searched for relevant literature. For each study, pre-defined data were extracted which included correction of kyphosis, loss of correction, hospital stay, operative time, blood loss during surgery as the outcome variables. Studies were also screened for the complications.

RESULTS

Eleven studies were evaluated for qualitative analysis and quantitative synthesis of the data in our review. The result demonstrated significant difference with most correction achieved in combined approach subgroup. Though no significant difference was found, the anterior group was having maximum loss of correction. Combined approach showed significantly more operative time and blood loss followed by posterior approach and then anterior approach alone. The improvement in VAS was significantly more in anterior subgroup when compared to combined approach.

CONCLUSION

Cervical alignment is best restored by combined approach compared to the other two. Anterior only approach showed more correction than posterior approach. However, there is no significant difference between all three approaches in loss of correction at long-term follow-up. Anterior only approach is superior to posterior and combined approach on basis of intraoperative and perioperative parameters.

LEVEL OF EVIDENCE I

Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.

Subaxial cervical articular process subluxation and dislocation: Cervical locked facet injuries in dogs

OBJECTIVE

To describe neurologic signs, diagnostic imaging findings, potential treatments, and outcomes in dogs with subaxial cervical articular process subluxation and dislocation, or a "locked facet."

STUDY DESIGN

Retrospective case series.

ANIMALS

Ten client-owned dogs.

METHODS

Dogs with a diagnosis of cervical locked facets were identified through medical records and imaging reports searches. Data on presenting signs, diagnostic findings, treatment, and outcome were recorded.

RESULTS

All cases were small or toy-breed dogs with preceding trauma. Four dogs were tetraplegic with intact pain perception, five were nonambulatory tetraparetic, and one was ambulatory tetraparetic, with half of the tetraparetic dogs having worse motor function in the thoracic limbs. The only sites affected were C5/6 (n = 6) and C6/7 (n = 4). All dogs had unilateral dorsal displacement of the cranial articular process of the caudal vertebra relative to the caudal articular process of the cranial vertebra at the luxation site. Five dogs were treated surgically, three by external coaptation, one by restriction, and one was euthanized the day after diagnosis. All dogs with outcome data (n = 8) became ambulatory. Nonambulatory dogs returned to ambulation in a median of 4 weeks (IQR 1-12; range 1-28).

CONCLUSION

In these dogs, locked facet injuries affected the caudal cervical vertebrae in small breeds and could be identified on imaging through the presence of dorsal displacement of a cranial articular process. Our small cohort had a functional recovery regardless of treatment.

CLINICAL SIGNIICANCE

Locked facet injuries should be a differential for small or toy-breed dogs with a cervical myelopathy secondary to trauma.

A biomechanical analysis of anterior cervical discectomy and fusion alone or combined cervical fixations in treating compression-extension injury with unilateral facet joint fracture: a finite element study

Background

Compression-extension injury with unilateral facet joint fracture is one of the most devastating injuries of subaxial cervical spine. However, it is not yet clear which fixation technique represents the optimal choice in surgical management. This study aims to assess the construct stability at the operative level (C4/C5 cervical spine) following anterior cervical discectomy and fusion (ACDF) alone and combined fixation techniques (posterior-anterior fixations).

Methods

A previously validated three-dimensional C2-T1 finite element model were modified to simulate surgical procedures via the anterior-only approach (ACDF) and combined cervical approach [(transarticular screw, lateral mass screw, unilateral pedicle screw, bilateral pedicle screw) + ACDF, respectively] for treating compression-extension injury with unilateral facet joint fracture at C4/C5 level. Construct stability (range of rotation, axial compression displacement and anterior shear displacement) at the operative level was comparatively analyzed.

Results

In comparison with combined fixation techniques, a wider range of motion and a higher maximum von Mises stress was found in single ACDF. There was no obvious difference in range of motion among transarticular screw and other posterior fixations in the presence of anterior fixation. In addition, the screws inserted by transarticular screw technique had high stress concentration at the middle part of the screw but much less than 500 MPa under different conditions. Furthermore, the variability of von Mises stress in the transarticular screw fixation device was significantly lower than ACDF but no obvious difference compared with other posterior fixations.

Conclusions

Of the five fixation techniques, ACDF has proven poor stability and high structural stress. Compared with lateral and pedicle screw, transarticular screw technique was not worse biomechanically and less technically demanding to acquire in clinical practice. Therefore, our study suggested that combined fixation technique (transarticular screw + ACDF) would be a reasonable treatment option to acquire an immediate stabilization in the management of compression-extension injury with unilateral facet joint fracture. However, clinical aspects must also be regarded when choosing a reconstruction method for a specific patient.

Numerical Investigation of Spinal Cord Injury After Flexion-Distraction Injuries At the Cervical Spine

Flexion-distraction injuries frequently cause traumatic cervical spinal cord injury (SCI). Post-traumatic instability can cause aggravation of the secondary SCI during patient's care. However, there is little information on how the pattern of disco-ligamentous injury affects the SCI severity and mechanism. This study objective was to analyze how different flexion-distraction disco-ligamentous injuries affect the SCI mechanisms during post-traumatic flexion and extension. A cervical spine finite element model including the spinal cord was used and different combinations of partial or complete intervertebral disc (IVD) rupture and disruption of various posterior ligaments were modeled at C4-C5, C5-C6 or C6-C7. In flexion, complete IVD rupture combined with posterior ligamentous complex rupture was the most severe injury leading to the most extreme von Mises stress (47 to 66 kPa), principal strains p1 (0.32 to 0.41 in white matter) and p3 (-0.78 to -0.96 in white matter) in the spinal cord and to the most important spinal cord compression (35 to 48 %). The main post-trauma SCI mechanism was identified as compression of the anterior white matter at the injured level combined with distraction of the posterior spinal cord during flexion. There was also a concentration of the maximum stresses in the gray matter after injury. Finally, in extension, the injuries tested had little impact on the spinal cord. The capsular ligament was the most important structure in protecting the spinal cord. Its status should be carefully examined during patient's management.

Circumferential Operations of the Cervical Spine

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

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.

Comparison of anterior-only versus combined anterior and posterior fusion for unstable subaxial cervical injuries: a meta-analysis of biomechanical and clinical studies

OBJECTIVE

The purpose of the present study was to perform a meta-analysis comparing biomechanical and clinical outcomes between anterior-only and combined anterior and posterior fusions to determine which method of cervical fusion yielded better results for unstable cervical injuries.

METHODS

The MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Web of Science and SCOPUS electronic databases were searched for relevant articles published through 2000-2019 that compared the biomechanical and clinical outcomes of anterior-only and combined anterior and posterior fusion for unstable cervical fracture.

RESULTS

Eight biomechanical and four clinical studies were included in the analysis. There were significant biomechanical differences between the groups with respect to flexion-extension, axial rotation and lateral bending. Combined fusion provided better biomechanical stability for unstable cervical injuries than anterior-only fusion, regardless of the number of corpectomies or the presence of a posterior column injury. However, despite significant biomechanical differences, there were no significant differences in clinical outcomes, such as the degree of neurologic improvement and complications between the two groups.

CONCLUSION

Anterior-only and combined anterior and posterior fusions for unstable subaxial cervical injuries can both restore cervical stability. Although combined fusion might have some advantages in terms of stability biomechanically, there were no significant differences in clinical outcomes, such as the degree of neurologic improvement and perioperative complications. Therefore, rather than the routine use of combined fusion for unstable cervical injuries, the selective use of anterior-only or combined fusion according to the type of injury is recommended.

Sub-Axial Cervical Facet Dislocation: A Review of Current Concepts

Cervical facet dislocation is a serious injury that carries risks of short- and long-term morbidity. The optimal management of these injuries remains controversial with the ongoing debate regarding indications and requirements for closed reduction, timing, type of surgical approach and method of fixation. This review gives an update on the relevant anatomy, classification systems for sub-axial cervical facet dislocation and an overview of the current concepts regarding their management, including surgical approaches and the choice of implants.

Management of Unilateral Cervical Facet Joint Dislocation in Neurologically Intact Patients: Results of an Ao Spine latin American Survey

BACKGROUND

The treatment of unilateral CFD in patients without neurologic deficits remains controversial, especially in the choice of the best surgical approach. Our objective is to determine the way spine surgeons from Latin America manage this condition.

METHODS

A survey regarding management and surgical strategies was conducted by the AO Spine Latin American Trauma Study Group considering the treatment of unilateral CFD.

RESULTS

All AO Spine Latin American Trauma Study Group members were sent a link to the survey, among whom 285 replied, with 197 respondents answering all the questions. Nonsurgical management was considered by 25% of the surgeons. The majority stated that magnetic resonance imaging is necessary (65%) to treat this type of patient. A posterior approach was preferred by 44%, an anterior approach by 29%, and a combined approach by 25%, while 2.2% did not answer. Traction was not used by the majority of respondents (62%). In the setting of an anterior disk herniation, the majority of surgeons preferred to employ an anterior (45%) or combined (44%) approach versus an isolated posterior approach (only 0.5%). Comparing early versus late cervical trauma, fewer surgeons adopted an isolated anterior approach with the latter (29% vs. 15%).

CONCLUSIONS

Wide variations exist in the management of unilateral CFD by Latin American surgeons, with early injuries generally treated using either an anterior or posterior approach and treated early but after an MRI, while a combined approach is used more commonly with late injuries. Either an anterior or combined approach is used when disk herniation is present.

An Experimental Study on the Safety and Mechanism of Reduction of Subaxial Cervical Facet Dislocation Using Z-Shape Elevating-Pulling Reduction Technique

OBJECTIVE

We sought to clarify the safety and unlocking mechanism of the Z-shape elevating-pulling closed reduction (ZR) technique and to analyze the differences in facet contact force and intraspinal pressure during subaxial facet dislocation reduction using the ZR technique and traditional skull traction closed reduction (SR).

METHODS

In 15 human cadaveric skull-neck-thorax specimens, reproducible unilateral and bilateral facet dislocations (UFDs/BFDs) were created at the C5-C6 level and then reduced by applying the ZR and SR techniques, respectively. Tekscan FlexiForce A-201 pressure sensors were used to measure the anterior and posterior intraspinal pressure and injured facet contact force under physiological conditions and before and after reduction. The maximum pressures during the reduction process were recorded.

RESULTS

After creation of the facet dislocation, the anterior and posterior intraspinal pressure and facet contact force were significantly increased relative to normal (P < 0.001). The UFDs and BFDs of all specimens were successfully reduced by both ZR and SR, and the intraspinal pressure and facet contact force were significantly reduced compared with before reduction (P < 0.001). Compared with SR, the maximum posterior intraspinal pressure during BFD reduction (P = 0.027) and the maximum facet contact force during UFD reduction (P < 0.001) were lower when ZR was used for closed reduction.

CONCLUSIONS

Our findings suggest that ZR and SR can both be used to reduce subaxial facet dislocation and decompress the spinal cord. However, the ZR technique appears to safer and more effective than the SR technique for closed reduction of subaxial facet dislocations.

Comparison of Two Intervertebral Disc Failure Models in a Numerical C4-C5 Trauma Model

The intervertebral disc (IVD) is essential for the mobility and stability of the spine. During flexion-distraction injuries, which are frequent at the cervical spine level, the IVD is often disrupted. Finite element studies have been done to investigate injury mechanisms and patterns at the cervical spine. However, they rarely include IVD failure model. The aim of this paper was to implement and compare two types of IVD failure models and their impact on hyperflexion and hyperflexion-compression injuries simulations. The failure models were tested on a detailed C4-C5 finite elements model. The first failure model consisted in a maximal strain model applied to the elements of the annulus and nucleus. The second failure model consisted in the implementation of a rupture plane in the middle of the IVD with a tied interface created between the two sections. This interface is defined by threshold stress values of detachment in traction and shearing. The two failure models were tested in flexion only and in flexion-compression. The model without inclusion of an IVD failure model was also tested. Loads at failure and injury patterns were reported. Both failure models produce failure loads that were consistent with experimental data. Injury patterns observed were in agreement with experimental and numerical studies. However, in flexion-compression, the rupture plane model simulation reached important energy error due to high deformations in the IVD elements. Also, without inclusion of an IVD failure model, energy error forced the end of the simulation in flexion-compression. Therefore, inclusion of IVD failure model is important since it leads to realistic results, but the maximal strain failure model is recommended.

Delayed Occurrence of C3 Vertebra Anterior Subluxation Diagnosed after Surgery for Epidural Hematoma

A case of delayed occurrence of C3 vertebra anterior subluxation diagnosed 10 days after surgery for epidural hematoma is herein described. A 56-year-old man underwent surgery for right epidural hematoma. No spinal fracture was identified on the cervical–spinal computed tomography (CT) on arrival. The patient developed neck pain after the craniotomy, and cervical magnetic resonance imaging 5 days postoperatively revealed a disruption of the C3–C4 posterior ligament complex. The patient was conservatively treated with immobilization. Cervical CT 10 days postoperatively revealed C3 vertebra anterior subluxation. Posterior fixation surgery was performed 21 days after admission, and the postoperative course was uneventful. This case suggests that awareness of delayed occurrence of cervical dislocation after traumatic intracranial hemorrhage should be increased among neurosurgeons.

Facet Joints of the Spine: Structure–Function Relationships, Problems and Treatments, and the Potential for Regeneration

The zygapophysial joint, a diarthrodial joint commonly referred to as the facet joint, plays a pivotal role in back pain, a condition that has been a leading cause of global disability since 1990. Along with the intervertebral disc, the facet joint supports spinal motion and aids in spinal stability. Highly susceptible to early development of osteoarthritis, the facet is responsible for a significant amount of pain in the low-back, mid-back, and neck regions. Current noninvasive treatments cannot offer long-term pain relief, while invasive treatments can relieve pain but fail to preserve joint functionality. This review presents an overview of the facet in terms of its anatomy, functional properties, problems, and current management strategies. Furthermore, this review introduces the potential for regeneration of the facet and particular engineering strategies that could be employed as a long-term treatment.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

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

STUDY DESIGN

Retrospective radiographic and chart review.

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Surgical Management of Old Lower Cervical Dislocations With Locked Facet

STUDY DESIGN

Prospective study.

OBJECTIVE

To evaluate the role of the canal and vertebrae sagittal diameter (C/V) ratio in the treatment of old dislocations of the lower cervical spine.

SUMMARY OF BACKGROUND DATA

Few studies have reported the management of old dislocations of the lower cervical spine. Conservative treatments including the use of a Halo vest, neck brace, and prolonged traction have been problematic. Operative treatment consisted of a primary or staged reduction and fusion using an anterior, posterior, or combined approach.

METHODS

Fourteen consecutive patients with old dislocations of the lower cervical spine were included in this series. The preoperative C/V value was calculated based on the measurement on the neutral sagittal computed tomography at the most narrow place of the dislocated segments. Closed reduction was attempted in 9 patients with moderate stenosis (C/V>0.5). Five patients with severe stenosis (C/V≤0.5) were treated with a primary combined anterior and posterior operation. Patient's radiographic information, pain, and neurological function were assessed and recorded before and after surgery.

RESULTS

Closed reduction followed by anterior cervical discectomy and fusion was performed in 3 of 9 patients with moderate stenosis. Eleven patients underwent circumferential release, posterior reduction, and fixation followed by anterior fusion. No severe complications were found. The average operative time was 138±43 minutes. The average blood loss was 239±140 mL. The postoperative C/V value was significantly increased. The neurological status improved at least one grade in all 13 neurologically impaired cases except for 2 who had complete spinal cord injuries. Bony fusion was obtained in all patients at 1-year follow-up.

CONCLUSIONS

The C/V value plays an important role in determining surgical solutions for old lower cervical dislocations with locked facets. Favorable clinical outcomes can be achieved using closed reduction and surgical procedures with anterior or anterior plus posterior approaches.

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

BACKGROUND CONTEXT

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

PURPOSE

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

STUDY DESIGN

In vitro cadaveric biomechanical study was used as study design.

METHODS

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

RESULTS

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

CONCLUSIONS

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

A comprehensive review of the sub-axial ligaments of the vertebral column: part II histology and embryology

BACKGROUND

As important as the vertebral ligaments are in maintaining the integrity of the spinal column and protecting the contents of the spinal canal, a single detailed review of their histology and embryology is missing in the literature.

METHODS

A literature search using online search engines was conducted.

RESULTS

Single comprehensive reviews of the histology and embryology of the spinal ligaments are not found in the extant medical literature.

CONCLUSIONS

This review will be useful to those who study or treat patients with pathology of the spine.

Detecting Facet Joint and Lateral Mass Injuries of the Subaxial Cervical Spine in Major Trauma Patients

STUDY DESIGN

Radiologic imaging measurement study.

PURPOSE

To assess the accuracy of detecting lateral mass and facet joint injuries of the subaxial cervical spine on plain radiographs using computed tomography (CT) scan images as a reference standard; and the integrity of morphological landmarks of the lateral mass and facet joints of the subaxial cervical spine.

OVERVIEW OF LITERATURE

Injuries of lateral mass and facet joints potentially lead to an unstable subaxial cervical spine and concomitant neurological sequelae. However, no study has evaluated the accuracy of detecting specific facet joint injuries.

METHODS

Eight spinal surgeons scored four sets of the same, randomly re-ordered, 30 cases with and without facet joint injuries of the subaxial cervical spine. Two surveys included conventional plain radiographs series (test) and another two surveys included CT scan images (reference). Facet joint injury characteristics were assessed for accuracy and reliability. Raw agreement, Fleiss kappa, Cohen's kappa and intraclass correlation coefficient statistics were used for reliability analysis. Majority rules were used for accuracy analysis.

RESULTS

Of the 21 facet joint injuries discerned on CT scan images, 10 were detected in both plain radiograph surveys (sensitivity, 0.48; 95% confidence interval [CI], 0.26-0.70). There were no false positive facet joint injuries in either of the first two X-ray surveys (specificity, 1.0; 95% CI, 0.63-1.0). Five of the 11 cases with missed injuries had an injury below the lowest visible articulating level on radiographs. CT scan images resulted in superior inter- and intra-rater agreement values for assessing morphologic injury characteristics of facet joint injuries.

CONCLUSIONS

Plain radiographs are not accurate, nor reliable for the assessment of facet joint injuries of the subaxial cervical spine. CT scans offer reliable diagnostic information required for the detection and treatment planning of facet joint injuries.

Adjacent Level Ligamentous Injury Associated with Traumatic Cervical Spine Fractures: Indications for Imaging and Implications for Treatment

BACKGROUND

Magnetic resonance imaging (MRI) is a vital tool for detection of soft tissue injury (STI) after cervical spine injury (CSI). However, high cost, prolonged imaging time, and limited use in hemodynamically unstable patients necessitates that the utility of MRI in all patients with CSI be scrutinized.

METHODS

A retrospective review was performed of all patients treated for a CSI at a Level I trauma center between 2005 and 2010. Patient demographics, fracture characteristics, and associated STIs were collected. STIs were classified further into same level ligamentous injury, adjacent level ligamentous injury (ALLI), cord contusion, and traumatic herniated disc. ALLI was defined as anterior or posterior longitudinal ligament, ligamentum flavum, or supraspinous or interspinous ligamentous injury.

RESULTS

MRI was performed in 240 of 787 patients. Evidence of STI was identified in 54.6%. ALLI was the most common STI (80 of 240 patients); these injuries were subdivided into above, below, or both above and below the concurrent fracture level. Patients with ALLI were significantly more likely to have injured C3 (P < 0.01) and C5 (P < 0.03) levels, association with widened disc space (P = 0.03), and multiple CSIs (P = 0.008). The whole ALLI was included in the fixation strategy in 100% of patients with ALLI only above the concurrent fracture level and 87% of patients with ALLI only below the concurrent fracture level.

CONCLUSIONS

MRI detected an associated STI in about 55% of patients who underwent imaging. Injuries involving multiple fractured cervical levels, fractures at C3 and C5, and widened disc space should raise the treating physician's level of suspicion for ALLI. Our data show that treatment directed by MRI findings in select cases has substantial value.

Marrow edema variability in acute spine fractures

BACKGROUND CONTEXT

The presence or absence of marrow edema is used in the assessment of fracture acuity in magnetic resonance imaging (MRI). We have observed variability in the degree of marrow edema in acute trauma. Our aim was to characterize the utility of marrow edema in fracture detection and fracture acuity on MRI. We hypothesized that only vertebral body compression injuries reliably generate marrow edema and that distraction injuries or fractures without compression do not reliably generate marrow edema and may give a false negative MRI examination.

PURPOSE

To characterize the utility of marrow edema in fracture detection and fracture acuity on MRI.

STUDY DESIGN

Two-year single-center retrospective review of marrow edema in patients evaluated by both computed tomography (CT) and MRI in acute trauma setting.

PATIENT SAMPLE

The final study cohort consisted of 163 patients (mean age, 54.5 years; standard deviation, 23.5 years; range, 8-94 years; 85 men and 78 women).

OUTCOME MEASURES

A physiologic measure of marrow edema as assessed by T2-signal hyperintensity on short tau inversion recovery sequence MRI examination.

METHODS

After institutional review board approval, we conducted a retrospective review of 1,215 patients who were evaluated at our hospital for suspected spine trauma with a combination of CT and MRI. Patients were assessed for fracture presence, location, type, and absence or degree of marrow edema.

RESULTS

The investigation identified 189/1,215 patients who had acute fractures on CT, subsequently imaged within 48 hours by MRI. A total of 94/288 acute fractures did not generate marrow edema. There were 63 patients (83 acute fractures) whose mechanism of injury resulted exclusively in acute fractures with no marrow edema. A statistically significant difference in marrow edema was observed with acute vertebral body compression fractures compared with acute fractures with distraction or fractures without compression. Moreover, certain fracture types were identified that often generate little or no marrow edema in acute trauma setting.

CONCLUSIONS

There is variability in the presence or degree of marrow edema on MRI evaluation after traumatic injury. Only fractures derived from vertebral body compression reliably generate marrow edema. Fractures without compression and/or fractures with distraction do not reliably generate marrow edema and can lead to a false negative MRI. An awareness of fracture types that produce more or less marrow edema can be beneficial when evaluating fractures by MRI.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

[Spinal trauma: first aid from cross-sectional imaging]

The diagnosis of the traumatized spine is one of the key issues for trauma radiologists. The cross-sectional imaging procedures, computed tomography (CT) and magnetic resonance imaging (MRI) are the essential methods in spinal trauma radiology. These modalities are of great help in accurately assessing injury patterns and extent and in providing indications of patient outcome. In contrast to cross-sectional imaging, radiography has a role in the evaluation of minor spinal trauma only. It is generally accepted that trauma radiologists do not use typical classifications to evaluate the spine partly because such an ideal classification system does not yet exist. Not least because of this classification difficulty, eponyms and synonyms are widely used to describe traumatology of the spine as a high level of specific information is included in these various terms. The members of the trauma team should be aware of the strengths and limitations of the methods used in the assessment of the spine. This article provides a brief outline of fundamental knowledge about the diagnosis of spinal trauma.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Spinal cord injury after blunt cervical spine trauma: correlation of soft-tissue damage and extension of lesion

BACKGROUND AND PURPOSE

In patients with spinal cord injury after blunt trauma, several studies have observed a correlation between neurologic impairment and radiologic findings. Few studies have been performed to correlate spinal cord injury with ligamentous injury. The purpose of this study was to retrospectively evaluate whether ligamentous injury or disk disruption after spinal cord injury correlates with lesion length.

MATERIALS AND METHODS

We retrospectively reviewed 108 patients diagnosed with traumatic spinal cord injury after cervical trauma between 1990-2011. Plain films, CT, and MR imaging were performed on patients and then reviewed for this study. MR imaging was performed within 96 hours after cervical trauma for all patients. Data regarding ligamentous injury, disk injury, and the extent of the spinal cord injury were collected from an adequate number of MR images. We evaluated anterior longitudinal ligaments, posterior longitudinal ligaments, and the ligamentum flavum. Length of lesion, disk disruption, and ligamentous injury association, as well as the extent of the spinal cord injury were statistically assessed by means of univariate analysis, with the use of nonparametric tests and multivariate analysis along with linear regression.

RESULTS

There were significant differences in lesion length on T2-weighted images for anterior longitudinal ligaments, posterior longitudinal ligaments, and ligamentum flavum in the univariate analysis; however, when this was adjusted by age, level of injury, sex, and disruption of the soft tissue evaluated (disk, anterior longitudinal ligaments, posterior longitudinal ligaments, and ligamentum flavum) in a multivariable analysis, only ligamentum flavum showed a statistically significant association with lesion length. Furthermore, the number of ligaments affected had a positive correlation with the extension of the lesion.

CONCLUSIONS

In cervical spine trauma, a specific pattern of ligamentous injury correlates with the length of the spinal cord lesion in MR imaging studies. Ligamentous injury detected by MR imaging is not a dynamic finding; thus it proved to be useful in predicting neurologic outcome in patients for whom the MR imaging examination was delayed.

MDCT of acute subaxial cervical spine trauma: a mechanism-based approach

Injuries to the spinal column are common and road traffic accidents are the commonest cause. Subaxial cervical spine (C3–C7) trauma encompasses a wide spectrum of osseous and ligamentous injuries, in addition to being frequently associated with neurological injury. Multidetector computed tomography (MDCT) is routinely performed to evaluate acute cervical spine trauma, very often as first-line imaging. MDCT provides an insight into the injury morphology, which in turn reflects the mechanics of injury. This article will review the fundamental biomechanical forces underlying the common subaxial spine injuries and resultant injury patterns or “fingerprints” on MDCT. This systematic and focused analysis enables a more accurate and rapid interpretation of cervical spine CT examinations. Mechanical considerations are important in most clinical and surgical decisions to adequately realign the spine, to prevent neurological deterioration and to facilitate appropriate stabilisation. This review will emphasise the variables on CT that affect the surgical management, as well as imaging “pearls” in differentiating “look-alike” lesions with different surgical implications. It will also enable the radiologist in writing clinically relevant CT reports of cervical spine trauma.

Teaching Points

• Vertebral bodies and disc bear the axial compression forces, while the ligaments bear the distraction forces.

• Compressive forces result in fracture and distractive forces result in ligamentous disruption.

• Bilateral facet dislocation is the most severe injury of the flexion-distraction spectrum.

• Biomechanics-based CT reading will help to rapidly and accurately identify the entire spectrum of injury.

• This approach also helps to differentiate look-alike injuries with different clinical implications.

Management of subaxial cervical facet dislocation through anterior approach monitored by spinal cord evoked potential

STUDY DESIGN

Retrospective case series.

OBJECTIVE

To discuss the clinical efficacy of anterior cervical surgery of decompression, reduction, stabilization, and fusion in treating subaxial cervical facet dislocation without spinal cord injury or with mild spinal cord injury monitored by spinal cord evoked potential.

SUMMARY OF BACKGROUND DATA

The optimal treatment of lower cervical facet dislocation has been controversial. Because of the risk of iatrogenic damage of neurological function, it is challenging for surgeons to manage the lower cervical facet dislocation without or with mild spinal cord injury. To avoid the risks, more secure strategy need to be designed.

METHODS

A retrospective study was performed on 17 cases of subaxial cervical facet dislocation without spinal cord injury or with mild spinal cord injury treated by anterior cervical surgery under spinal cord evoked potential monitor from January 2008 to June 2012. There were 12 males, 5 females, with a mean age of 40.1 years (from 21 to 73 yr). Dislocation sites: 1 in C3-C4, 2 in C4-C5, 6 in C5-C6, 8 in C6-C7; 10 cases with unilateral cervical facet dislocation, 7 cases with bilateral dislocation. Thirteen patients were preoperatively classified as grade D and 4 as E according to Frankel standard. All patients were followed up for average of 16 months.

RESULTS

All operations were completed successfully. Postoperative radiographs showed that the sequence and curvature of the cervical spine were well recovered. And, evidence of intervertebral fusion was observed at 3 months in all cases. No redislocation or symptoms of spinal cord injury occurred. Thirteen cases with mild spinal cord injury recovered at 1 month after operation.

CONCLUSION

Anterior cervical surgery of decompression, reduction, stabilization, and fusion monitored by spinal cord evoked potential is an effective and safe method for treatment of subaxial cervical facet dislocation without or with mild spinal cord injury.

LEVEL OF EVIDENCE

4.

Distractive flexion injuries of the subaxial cervical spine treated with a posterior procedure using cervical pedicle screws or a combined anterior and posterior procedure

The purpose of this study was to compare the clinical and radiographic outcomes of patients with distractive flexion (DF) injuries of the subaxial cervical spine who had undergone a posterior procedure using cervical pedicle screw (CPS) fixation with those who had undergone a combined anterior and posterior procedure. Recommendations for the surgical treatment of DF injuries of the subaxial cervical spine remain controversial. There are few clinical reports of posterior CPS fixation for DF injuries. We retrospectively reviewed the clinical records and radiographs of 50 consecutive patients with DF injuries of the subaxial cervical spine treated at the Imakiire General Hospital. Group 1 consisted of 24 patients who underwent posterior wiring fixation and fusion with additional anterior decompression and fusion. Group 2 consisted of 26 patients who underwent posterior decompression and fusion with CPS fixation. Group 1 had a significantly longer operation time (295.4 minutes) than Group 2 (163.3 minutes). Group 1 had significantly higher blood loss (689.1g) than Group 2 (313.7 g). No patient in Group 1 or 2 developed postoperative neurological worsening. The mean loss of kyphotic correction was 1.6° and 0.1° in Groups 1 and 2, respectively, and the loss of kyphotic correction in Group 2 was significantly less than that of Group 1. We suggest that posterior procedures with CPS fixation are reasonable for the management of cervical DF injuries.

Tratamento cirurgico das fraturas luxações da coluna cervical baixa por redução aberta e sem uso de tração craniana

OBJETIVO: Demonstrar os resultados do tratamento cirúrgico na coluna cervical baixa em 34 pacientes portadores de fratura-luxação traumática tratada através de técnica cirúrgica de artrodese com fixação sem o auxilio de tração craniana. MÉTODOS: Os pacientes foram avaliados clínica e radiologicamente e acompanhados por um período de um a quatro anos. RESULTADOS: A consolidação clínica e radiológica da artrodese foi observada em todos os 34 pacientes, sendo que quatro evoluíram com infecção do sítio cirúrgico posterior quando houve necessidade desse acesso complementar. RESULTADOS: A realização de redução da fratura luxação da coluna cervical baixa sem o uso de tração craniana juntamente com acesso cirúrgico por via anterior mostrou bons resultados com melhora clinica e radiológica, além de baixo índice de complicações neurológicas.

A biomechanical assessment of soft-tissue damage in the cervical spine following a unilateral facet injury

BACKGROUND

Unilateral cervical spine facet injuries encompass a wide spectrum, including subluxations, dislocations, and fractures, and the instability produced varies greatly. The extent of anatomical disruption secondary to a unilateral facet injury is poorly understood, and few biomechanical studies have quantified the associated kinematics. The purpose of this study was to develop an experimental method that reliably produces an impending unilateral facet dislocation (perched facet) in cadaveric cervical spines and to identify the soft-tissue damage and resulting changes in cervical spine range of motion and neutral zone associated with this injury.

METHODS

Nine fresh-frozen cadaveric human spinal motion segments (C4-C5 or C6-C7) were mounted in a spinal loading simulator to induce a perched unilateral facet injury based on a previously described mechanism of flexion and bending with increasing rotation. Loads were applied to simulate and measure flexion-extension, lateral bending, and axial rotation motions before and after achieving a perched facet. Preinjury and postinjury range of motion and neutral zone were analyzed with use of paired t tests for each movement. Systematic qualitative inspection and gross dissection were then performed to define the soft-tissue injury pattern.

RESULTS

Range of motion and neutral zone increased following the reduction of this injury; the largest increase (294%) occurred in contralateral axial rotation (i.e., right axial rotation after a perched left facet). Postinjury dissections revealed bilateral capsular tears, 50% disc disruption, and 50% tearing of the ligamentum flavum in most specimens. The interspinous and supraspinous ligaments were stretched in less than half of the specimens and were never completely disrupted. The longitudinal ligaments were occasionally torn as extensions of anulus fibrosus disruptions.

CONCLUSIONS

This study indicates that the anulus fibrosus, nucleus pulposus, and ligamentum flavum are important cervical spine stabilizers. Facet capsules were often torn bilaterally, implying a more advanced injury than a unilateral facet injury. These discoligamentous injuries result in increases in range of motion and neutral zone.

CLINICAL RELEVANCE

The results from this work provide further insight into the expected injury and associated instability present in a traumatic unilateral facet injury in the cervical spine.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Magnetic resonance imaging in cervical facet dislocation: a third world perspective

Study Design

Retrospective case series.

Purpose

The objective of our study was to determine the change in management brought about by magnetic resonance imaging (MRI) of the cervical spine in alert and awake patients with facet dislocation and spinal cord injury presenting within 4 hours after injury.

Overview of Literature

Spinal cord injury is a common clinical entity. The role of MRI is well established in evaluating spinal trauma. However, the time at which MRI should be used is still controversial.

Methods

Retrospective data from 2002-2010 was evaluated. All of the alert and awake patients with spinal cord injury, based on clinical examination with facet dislocation diagnosed on lateral cervical spine X-rays, were included. A questionnaire was also conducted, the data of which consisted of demographic details including age and sex, the mechanism of injury, clinical examination, X-ray findings, MRI findings, whether or not surgery was performed and the time elapsed since injury. Data was analyzed using SPSS ver. 17.0. Continuous variables such as age were expressed in terms of mean ± standard deviation. Categorical variables such as change in management, X-ray/MRI findings and neurological motor level were assessed in terms of percentage.

Results

Fifty patients participated in our study. All these patients had spinal cord injury with defined motor levels. The mean age was 35.5 ± 8.95 years (range, 20 to 52 years). Fifty percent showed a motor level at C6 level. None of the patients required any change in management based on the MRI.

Conclusions

MRI of the spine in awake patients within 4 hours after injury does not change the management of patients. However, we can hypothesize that such patients can proceed to traction without waiting for the MRI.

Spinal facet joint biomechanics and mechanotransduction in normal, injury and degenerative conditions

The facet joint is a crucial anatomic region of the spine owing to its biomechanical role in facilitating articulation of the vertebrae of the spinal column. It is a diarthrodial joint with opposing articular cartilage surfaces that provide a low friction environment and a ligamentous capsule that encloses the joint space. Together with the disc, the bilateral facet joints transfer loads and guide and constrain motions in the spine due to their geometry and mechanical function. Although a great deal of research has focused on defining the biomechanics of the spine and the form and function of the disc, the facet joint has only recently become the focus of experimental, computational and clinical studies. This mechanical behavior ensures the normal health and function of the spine during physiologic loading but can also lead to its dysfunction when the tissues of the facet joint are altered either by injury, degeneration or as a result of surgical modification of the spine. The anatomical, biomechanical and physiological characteristics of the facet joints in the cervical and lumbar spines have become the focus of increased attention recently with the advent of surgical procedures of the spine, such as disc repair and replacement, which may impact facet responses. Accordingly, this review summarizes the relevant anatomy and biomechanics of the facet joint and the individual tissues that comprise it. In order to better understand the physiological implications of tissue loading in all conditions, a review of mechanotransduction pathways in the cartilage, ligament and bone is also presented ranging from the tissue-level scale to cellular modifications. With this context, experimental studies are summarized as they relate to the most common modifications that alter the biomechanics and health of the spine-injury and degeneration. In addition, many computational and finite element models have been developed that enable more-detailed and specific investigations of the facet joint and its tissues than are provided by experimental approaches and also that expand their utility for the field of biomechanics. These are also reviewed to provide a more complete summary of the current knowledge of facet joint mechanics. Overall, the goal of this review is to present a comprehensive review of the breadth and depth of knowledge regarding the mechanical and adaptive responses of the facet joint and its tissues across a variety of relevant size scales.

The development and evaluation of the subaxial injury classification scoring system for cervical spine trauma

BACKGROUND

Fractures and dislocations of the subaxial cervical spine may give rise to devastating consequences. Previous algorithms for describing cervical trauma largely depend on retrospective reconstructions of injury mechanism and utilize nonspecific terminology which thus diminish their clinical relevance add to the difficulty of educating doctors and performing prospective research.

QUESTIONS/PURPOSES

We characterized the potential benefits of the Subaxial Injury Classification (SLIC) scale which considers three major variables that influence spinal stability: morphology, integrity of the discoligamentous complex, and neurologic status. Each category was assigned a certain number of points based on the severity of the injury which are added together to generate a total score; this value provides prognostic information and may also be useful for directing subsequent management (ie, nonoperative treatment versus operative intervention).

METHODS

We examined the individual components that comprise the SLIC paradigm and reviewed the manner in which cervical injuries are scored and stratified. We also critically assessed the preliminary data comparing the SLIC scheme to preexisting classification systems.

RESULTS

The results of a preliminary analysis demonstrate that the intraclass coefficients (ICC) for the three primary components range between 0.49 and 0.90, suggesting that the overall reliability of the SLIC system appears to be at least as good as that of other conventional schemes for classifying subaxial cervical spine trauma (ICC between 0.41 and 0.53).

CONCLUSIONS

This scheme will hopefully facilitate the development of evidence-based guidelines that may influence other aspects of the therapeutic decision-making process (eg, which operative approach is most appropriate for a particular injury). We anticipate its accuracy and reproducibility will increase over time as surgeons become more familiar with the protocol.