Bilateral Facet Research Articles

Traumatic L4 –L5 Spondylolisthesis with Vertical Shear Fracture of Pelvis

We report a case of traumatic listhesis of L4 over L5 vertebra with vertical shear fracture of pelvis in a 45 year old male. The patient was treated surgically immediately after the injury. His radiological and operative findings showed anterior listhesis of L4 over L5 vertebra with dislocation of bilateral facet joints at L3-L4 and L4-L5 level and fracture of spinous processes of L4-L5 vertebra with fracture of right lamina of L4 vertebra. There was also evidence of diastasis of pubic symphysis with displaced communited fracture of right iliac bone. Surgically he was treated by decompression and reduction, L3-L5 pedicular screw fixation along with L3 to L4 laminectomy, L3-L4 and L4-L5 discectomy and reconstruction plating for pubic diastasis and right iliac bone fracture. Key-words: Traumatic Spondylolisthesis, Pubic Diastasis, Vertical Shear fracture

Outcomes of extended transforaminal lumbar interbody fusion for lumbar spondylosis

This study aims to assess the results of extended transforaminal lumbar interbody fusion (TLIF) for a two surgeon, single institution series. In total, extended TLIF with bilateral decompression was performed in 57 patients. Pain, American Spinal Injury Association scores, patient demographics, body mass index (BMI), perioperative indices and radiographic measurements were recorded and analysed. The surgeries were performed between February 2011 and January 2014 on 38 women and 19 men. The mean patient age was 62.86years, and the mean BMI was 30.31kg/m2. In 49 patients, spondylolisthesis was the primary indication. The mean intraoperative time was 284.65min, and this decreased as the series progressed. The median length of stay was 5days (range: 2–9). The surgical complication rate was 19.3%. Two patients died from cardiopulmonary complications. Single level TLIF was performed in 78.9% of the cohort, with L4/5 the most commonly fused level. Significant pain reduction was achieved from a mean (±standard deviation) preoperative visual analogue scale (VAS) of 8.28±1.39 to 1.50±1.05 at 12months postoperatively. No patients deteriorated neurologically. Spondylolisthesis was significantly corrected from a preoperative mean of 6.82mm to 2.80mm postoperatively. Although there is a learning curve associated with the procedure, extended TLIF with bilateral facet joint removal and decompression appeared to be a safe and effective alternative to other fusion techniques, and our results were comparable to other published case series. The stabilisation and correction of spinal deformity reduces pain, aids neurologic recovery and improves quality of life.

Poster 145 Delayed Diagnosis of Bilateral Cervical Facet Dislocation: A Case Report

PM&RVolume 7, Issue 9S p. S139-S139 Pain and Spine Medicine Poster 145 Delayed Diagnosis of Bilateral Cervical Facet Dislocation: A Case Report Anupam Sinha DO, Anupam Sinha DO Rothman Institute, Philadelphia, PA, United StatesSearch for more papers by this authorMadhuri Dholakia MD, Madhuri Dholakia MD Rothman Institute, Philadelphia, PA, United StatesSearch for more papers by this author Anupam Sinha DO, Anupam Sinha DO Rothman Institute, Philadelphia, PA, United StatesSearch for more papers by this authorMadhuri Dholakia MD, Madhuri Dholakia MD Rothman Institute, Philadelphia, PA, United StatesSearch for more papers by this author First published: 08 September 2015 https://doi.org/10.1016/j.pmrj.2015.06.183Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume7, Issue9SSeptember 2015Pages S139-S139 RelatedInformation

In vitro biomechanical evaluation of internal fixation techniques on the canine lumbosacral junction.

Few biomechanical studies have evaluated the effect of internal stabilization techniques after decompressive surgery on the stability of the canine lumbosacral junction. The purpose of this canine cadaver study is to evaluate the stability of the canine lumbosacral (LS) spine in flexion and extension following laminectomy and discectomy and then stabilization with each of the three techniques: pins and polymethylmethacrylate (P/PMMA), two dorsal locking plates (SOP) or bilateral transarticular facet screws (FACET).Using a cantilever biomechanical system, bending moments were applied to the LS and range of motion (ROM) was recorded via a rotational potentiometer. With 3 Nm, the ROM (n = 4 in each group) for P/PMMA, SOP and FACET were 1.92 ± 0.96°, 2.56 ± 0.55°and 3.18 ± 1.14°, respectively. With moments up to 35 Nm, the P/PMMA specimens appeared stable. Sacroiliac motion in the SOP and FACET groups invalidated further comparisons. Each of the stabilization techniques (P/PMMA, SOP, and FACET) significantly decreased the range of motion in flexion and extension for low bending moments.

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

Background ContextAnterior 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. PurposeThis 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 DesignIn vitro cadaveric biomechanical study was used as study design. MethodsSeven 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). ResultsIn 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). ConclusionsThis 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.

Assessment of Ultrasound as a Diagnostic Modality for Detecting Cervical Spine Fractures in Head-Injured Patients

Background Early cervical spine clearance is extremely important in patients with head injuries and may be difficult to achieve in emergency setting. This is especially true in hemodynamically unstable unconscious patients and in low-resource settings. This study aimed to assess the feasibility of standard portable ultrasound in detecting cervical spine injuries in severe head-injured patients. Materials and Methods This retro-prospective pilot study performed over 1-month period (June–July 2013) after approval from the institutional ethics committee. During the study period the technique of cervical ultrasound was standardized by the authors and tested on 10 admitted patients of cervical spine injury. To assess feasibility in the emergency setting, hemodynamically stable patients with isolated severe head injury (GCS ≤8) coming to emergency department underwent ultrasound examination on a portable ultrasound machine (MicroMaxx, Sonosite Inc., Bothell, Washington, United States). Observations and Results Ultrasound examination of the cervical spine was possible in the emergency setting, even in unstable patients and could be done without moving the neck. The best window for the cervical spine was through the anterior triangle using the linear array probe (6–13 MHz). In the 10 patients with documented cervical spine injury, bilateral facet dislocation at C5–6 was seen in four patients and at C6–7 was seen in three patients. C5 burst fracture was present in one and C2 anterolisthesis was seen in one patient. Cervical ultrasound could easily detect fracture lines, canal compromise, and ligament injury in all cases. Conclusion Cervical ultrasound may be a useful tool for detecting cervical spine injury in unconscious patients, especially those who are hemodynamically unstable. It may be particularly useful in the resource-constrained setting of developing countries

Management of post-traumatic bilateral jumped facets: a systematic review

Background: Bilateral jumped facets (BJF) are serious cervical spine injuries that require reduction and surgical stabilization. Closed reduction often performed, however, the argument of having disc herniation suggested deferred treatment until MRI is done. The later has been criticised for delaying the treatment. Methodology: We conducted a systematic review focusing on BJF in order to assess the validity of performing an MRI prior to closed reduction. The immediate neurological state after reduction and long term outcome were the primary goals. Results: A total of 49 articles were found (1973-2014). Only 20 of them fit our criteria. A total of 203 BJF were evaluated with C6/7 and C5/6 being the most common level of injury. Closed reduction was performed in 194 patients with no MRI in 118 patients. Clinical changes had occurred in 7 patients (3 improved, 2 worsened, 2 transient worsening). The long term outcome showed no significant difference between the two groups who had closed reduction before or after the MRI (p&gt;0.05) Conclusion: The risk of neurological worsening with closed reduction prior to MRI is low and insignificant. The MRI will be helpful post reduction to assess the status of the cord and adequacy of closed reduction, especially in comatose patients.

How to Reduce Bilateral Cervical Facet Joint Dislocation in Anterior Approach: A Trick to Avoid Anterior-Posterior-Anterior Surgical Procedures

Introduction Cervical facet joint dislocation is a common injury of the lower cervical spine. These flexion distraction lesions in cervical spine occur as a subluxation or unilateral/bilateral dislocation of the facet joints, which often be accompanied by direct spinal cord and nerve root injury. The presence of herniated intervertebral disc requires an anterior approach to decompress the spinal cord. Because often it is not possible to reduce facet joint dislocation while performing anterior surgery an additional posterior approach and then the fixation trough an anterior approach again is necessary. This method (supine-prone-supine) creates difficulties for surgeons because of the prolonged operation time; the need for frequent changes in patient position; and a subsequent high incidence of complications. Materials and Methods On the basis of a case, we present a maneuver to use pins such as joysticks in vertebral body during anterior approach to reduce dislocated facet joints in cervical spine fractures. After cervical discectomy/corpectomy, we use the pins to put the vertebral body in kyphotic position following rotational motion to reduce the facet joints. Results and Conclusion: Since we implemented this procedure, we had no more to perform posterior approach in surgical treatment in the last 15 cases of bilateral facet joint dislocation with herniated intervertebral disc in cervical trauma.

The Risk Factors of Pedicle Screws Loosening after Spinal Instrumentations

Introduction Implant instability has a relatively low rate of incidence, however revision interventions in those cases are expensive, difficult to perform and have a considerable frequency of poor results. Even though various novel technologies are available, this problem is not resolved yet and it is essential to assess risk factors that may lead to this complication. The objective of this study is to determine risk factors for the pedicle screw instability development after spinal instrumentations. The objective of this study is to assess risk factors in relation to pedicle screw instability development. Materials and Methods This is a prospective randomized study of 120 spinal instrumentations performed in case of traumatic injuries and spinal degenerative diseases of lumbar and thoracolumbar spine. Preoperatively patients underwent CT examination and bone density was measured in Hounsfield units. CT scans utilized slice thickness 0.5 mm. Tube voltage was 120 kV, current 300 mA, auto mA range 180 to 400; 1.0 s/3.0 mm/0.5 × 32, and helical-pitch 21.0. Transpedicular fixation was used to treat patients either as standalone technique or in combination with various types of interbody fusion, also if indicated, decompression of nerve roots and spinal cord was performed. Patients with suboptimal screws placement were excluded from this study. The duration of follow-up was 1 year; cases with screws loosening were registered. Logistic regression analysis was utilized to assess the relationship between expected risk factors (extension of decompression, bone density, extension of fixation), and the rate of screws loosening. Results Extensive decompression resulting in a total or subtotal bilateral facet joints total resection results in the considerable increase in frequency of pedicle screws instability. The parameters of the logistic regression model were chi-square = 14.78227, p = 0.0001209; В0 = −0.9360933, р = 0.0005580619; В1 = 1.479709, р = 0.0002964492; OR (odds ratio) = 4.391667 (2.001693; 9.635212). It was estimated that the rate of implant instability has a strong inverse relation to the bone density measured in HU during CT investigation. The parameters of the logit regression model were chi-square = 12.32050, p = 0.0004486; B0 = −1.846886, p = 0.007698078; B1 = 0.01737968, p = 0.00169618; OR = 56.7059 (4.706; 683.2748). Even though the extension of fixation in general turned out to be irrelevant to a screw loosening, it was pointed out that S1 vertebra included into a fixed area is an additional risk factor for implant instability formation. The estimated parameters of logistic regression model were chi-square = 4.882991 p = 0.0271296; B0 = −0.5221894, p = 0.01585754; B1 = 0.992193, p = 0.03159398; OR = 2.697143 (1.093079; 6.655126). The general nonlinear regression model that includes all listed previously contributing factors has a predictive value of 78.33%, goodness of fit chi-square = 34.96233 p = 0.0000001. Conclusions Apparently, surgical intervention should be planned thoroughly avoiding destabilizing overextended decompression because this could be a significant contributing factor for the implant instability formation in future. Bone quality must be taken in view while planning spinal instrumentation. If necessary, augmentation with bone cement must be performed to prevent implant instability formation. The extension of fixation to the level S1 must be clearly justified as it was estimated that it is an additional considerable risk factor for pedicle screws loosening.

“Thickened” ligamentum flavum caused by laminectomy

ObjectiveThe purpose of this study was to evaluate the effect of a laminectomy on the adjacent ligamentum flavum (LF) by measuring LF thickness using magnetic resonance imaging (MRI). Materials and methodsA total of 78 patients (31 man, 47 woman) with laminectomy were included in our study. After determination of laminectomy level, measurements were done from the thickest parts of the bilateral LF at the upper level of the laminectomy where bilateral facet joints were evident at the slice. ResultsIpsilateral ligamentum flavum with laminectomy was significantly thicker than the contralateral ligamentum flavum with laminectomy. ConclusionLaminectomy cause thickening of ligamentum flavum. Therefore we assume that it should kept in mind that LFH may develop at the adjacent level to the laminectomy and careful clinical and radiological assessments’ should be done to exclude LFH in cases who complain about the recurrence of complaints during the post-operative period after laminectomy.

Effects on single segmental lumbar stability after graded facetectomy and laminectomy: a finite element study

To explore the effects on degenerative single segmental lumbar spinal stability after posterior graded laminectomy and facetectomy by a finite element method. A finite element model of L3-S1 segments with a single segmental degeneration at L4-5 level was established. Different models of L4-L5 segmental instability after posterior graded laminectomy and facetectomy were established. And interior 1/3, 1/2, 2/3 of laminar and bilateral facet joints were resected. Physical loads were applied to the models and the changes of range of motion (ROM) at L4-5 level in different models were recorded during flexion, extension, lateral bending and rotation. As compared to preoperative model, after resecting 1/3 bilateral facet joints at L4-5 level, L4-5 segmental ROM increased 18% during flexion, 27% during extension and 45% during torsion. And the increased degree of ROM became more obvious along with a greater resection range of bilateral facet joints. No significant difference existed in L4-5 segmental ROM during lateral bending in all models. Facet joints play vital roles in lumbar segmental stability. And segmental instability may occur when 1/3 bilateral facet joints are resected.

Subacute Posttraumatic Ascending Myelopathy After Excessive Closed Reduction of Bilateral Cervical Facet Dislocation

Subacute Posttraumatic Ascending Myelopathy After Excessive Closed Reduction of Bilateral Cervical Facet Dislocation

Bilateral Facet Dislocation with Neural Compression from an Avulsed Posterior Longitudinal Ligament

Background and Importance: A review of the literature failed to show evidence of normal appearing posterior longitudinal ligament avulsion as a cause of spinal cord compression after bilateral cervical facet dislocations. We report a case of the posterior longitudinal ligament (PLL) avulsion causing spinal cord compression after bilateral cervical facet dislocation. Clinical presentation: A 93 year female presented with upper extremity numbness and bilateral C5-C6 facet dislocations. The patient was immediately taken for closed reduction and anterior cervical decompression with fusion (ACDF). After awake, closed reduction, an ACDF was immediately performed. After a complete discectomy procedure, the spinal cord could be visualized secondary to an absent PLL. A nerve hook was used to explore behind the C6 vertebral body to decompress the spinal cord. A segment of normal appearing posterior longitudinal ligament, which had avulsed from the superior aspect of C5, was found folded behind the C6 vertebra causing cord compression. There was no herniated disk material discovered. Conclusion: In addition to herniated disk material, avulsed PLL is another potential source of cord compression after closed reduction of cervical facet dislocations and surgeons must be aware of this possible source of compression while exploring and decompressing the spinal canal. This case study elucidates that the PLL is a potential cause of spinal cord compression after traumatic bilateral cervical facet dislocations.

Assessment of ultrasound as a diagnostic modality for detecting potentially unstable cervical spine fractures in pediatric severe traumatic brain injury: A feasibility study.

Background:Early cervical spine clearance is extremely important in unconscious trauma patients and may be difficult to achieve in emergency setting.Objectives:The aim of this study was to assess the feasibility of standard portable ultrasound in detecting potentially unstable cervical spine injuries in severe traumatic brain injured (TBI) patients during initial resuscitation.Materials and Methods:This retro-prospective pilot study carried out over 1-month period (June–July 2013) after approval from the institutional ethics committee. Initially, the technique of cervical ultrasound was standardized by the authors and tested on ten admitted patients of cervical spine injury. To assess feasibility in the emergency setting, three hemodynamically stable pediatric patients (≦18 years) with isolated severe head injury (Glasgow coma scale ≤8) coming to emergency department underwent an ultrasound examination.Results:The best window for the cervical spine was through the anterior triangle using the linear array probe (6–13 MHz). In the ten patients with documented cervical spine injury, bilateral facet dislocation at C5–C6 was seen in 4 patients and at C6–C7 was seen in 3 patients. C5 burst fracture was present in one and cervical vertebra (C2) anterolisthesis was seen in one patient. Cervical ultrasound could easily detect fracture lines, canal compromise and ligamental injury in all cases. Ultrasound examination of the cervical spine was possible in the emergency setting, even in unstable patients and could be done without moving the neck.Conclusions:Cervical ultrasound may be a useful tool for detecting potentially unstable cervical spine injury in TBI patients, especially those who are hemodynamically unstable.

Outcomes of Extended Transforaminal Lumbar Interbody Fusion for Lumbar Spondylosis: A Retrospective Cohort Study

Objectives: The present study aims to assess the results of extended Transforaminal Lumbar Interbody Fusion (TLIF) for a two-surgeon, single institution series. Methods: 57 cases of extended TLIF with bilateral decompression were performed. Pain, ASIA scores, patient demographics, BMI, perioperative indices and radiographic measurements were recorded and analysed. Results: 57 operations were performed between February 2011 and January 2014, there were 38 female and 19 male patients. Mean patient age was 62.86 years, mean BMI was 30.31 kg/m2. In 49 patients spondylolisthesis was the primary indication. The mean intraoperative time was 284.65 min, this decreased as the series progressed. The median length of stay was 5 days, ranging from 2 to 9 days. The surgical complication rate was 22.8%. Two patients died from cardiopulmonary complications. 78.9% of the cohort had single-level TLIF, L4/5 was the most commonly fused level. Significant pain reduction was achieved from a mean Pre-operative VAS of 8.28 +/- 1.39 to post-op VAS of 1.50+/-1.05 at 12 months. No patients deteriorated neurologically. Spondylolisthesis was significantly corrected from a pre-operative mean of 6.82 mm to 2.80 mm post-operatively. There is a learning curve associated with the procedure. Discussion: TLIF with bilateral facet joint removal and decompression appeared to be a safe and effective alternative to other fusion techniques, and is comparable to other published case series. Stabilisation and correction of spinal deformity reduces pain, aids neurologic recovery and improves quality of life.

Vertebral rotatory subluxation in degenerative scoliosis: facet joint tropism is related.

A cross-sectional study. To identify facet tropism as one of the possible risk factors leading to vertebral rotatory subluxation (VRS). VRS has been considered as one of the prognostic factors for degenerative scoliosis. Although several risk factors of VRS, including age and Cobb angle, have been investigated, few studies exist that have evaluated the correlation between VRS and anatomical structures of the vertebral column. This retrospective study recruited 23 patients diagnosed with degenerative lumbar scoliosis with VRS and 20 patients with degenerative scoliosis without VRS. The lateral translation on coronal radiographs was measured and 5 mm was used as the cutoff value to define rotatory subluxation. Computed tomographic scans for facet joints were made for all lumbar levels. The difference between right and left facet angles was recorded as ΔFA. Facet tropism was defined as a difference between the bilateral facet angles of more than 10°. In this study, VRS was most commonly found at the L3-L4 level (49%) and, with decreasing frequency at L2-L3 (24%), L4-L5 (20%), and L1-L2 (7%). On the convex side of the main curve, face joints at levels with VRS were more coronally oriented compared with those at levels without VRS (41.64° ± 11.65° vs. 36.30° ± 10.99°, P = 0.034). ΔFA was also significantly different between levels with and without VRS (P = 0.005). A strong correlation was found between ΔFA and lateral translation, with a coefficient of 0.33 (P < 0.001). In addition, ΔFA and a larger Cobb angle were found to be significantly associated with VRS based on binary regression analysis, with an odds ratio of 4.68 and 2.14, respectively. Facet tropism was more significantly observed at levels with VRS. On the convex side of the main curve, facet joints at levels with VRS were more coronally oriented. A larger Cobb angle and severe facet tropism in degenerative scoliosis should be considered to be related to VRS.

Cervical Spine Injuries in Fayed Resort: Shallow Water Accidents

Background Data: Shallow-water diving injuries have devastating consequences for patients and their families in terms of requiring intensive use of resources in both the acute and rehabilitative phases of injury. With the final clinical outcome often poor, the question is raised as to whether a target group can be identified for whom to implement a preventive program. Purpose: Our aim is to evaluate the demographics, clinical features and outcomes of shallow-water diving injuries in Fayed resort. Study Design: A descriptive analytic cross section prospective study involving 20 patients with diving accidents. Patients and Methods: During the period from January 2011 to May 2014, 20 patients who presented with diving accidents from Fayed city were surgically treated in Suez Canal University Hospital in the Neurosurgery Department. Initial treatment was made according to Advanced Trauma Life Support guidelines, followed by neurologicaland radiological examination to determine the severity of the injury. Neurological classification was made according to the American Spinal Injury Association/International Medical Society of Paraplegia Impairment scale. Cervical traction was used in cases of subluxation. Surgery was performed in cases of spinal instability or cord compression. Results: Neurologically, eight patients had complete ASIA, grade A, spinal cord injury, eight had incomplete spinal cord injury ASIA grade B (1 patient), grade C (3 patients), grade D (4 patients). The other 4 were normal ASIA, grade E. Five patients presented with teardrop fractures, five burst fractures, eight patients presented with flexion distraction injury including five with bilateral locked facets and three unilateral locked facets and two presented with fracture of the posterior elements. Surgical fusion was done in sixteen patients including anterior approach in fourteen patients and combinedanterior and posterior approach in two patients. No neurological deterioration was recorded. Overall, 30% (6/20) patients improved neurologically during hospitalization with regard to the ASIA Impairment Scale. Conclusion: A very specific patient profile was identified, and the severity of shallowwater diving injuries was confirmed. These data should be used to motivate further educational and preventive programs for reducing the incidence of diving-related injuries. (2014ESJ087)

A novel lateral lumbar integrated plate-spacer interbody implant: in vitro biomechanical analysis

Background contextLateral spacers (LSs) are the standard of care for a lateral lumbar interbody fusion. However, various types of fixation, such as bilateral pedicle screws (BPSs), unilateral pedicle screws (UPSs), bilateral facet screws (BFSs), and lateral plates (LPs) have been reported to increase the stability of LSs. The biomechanics of a novel lateral interbody implant, which is an interbody spacer with an integrated plate and two bone screws (lateral integrated plate-spacer [IPS-L]), has not been investigated yet. PurposeTo compare the biomechanical stability of IPS-L and LS with and without supplemental instrumentation. Study designHuman lumbar cadaveric study evaluating the biomechanical stability of an IPS-L. MethodsEach of the six (L2–L5) spines was sequentially tested in intact; IPS-L; IPS-L+UPS; IPS-L+BPS; IPS-L+BFS; LS+BFS; LS+UPS; LS+BPS; LS; and LS+LP, using a load-control protocol in which a ±8 Nm moment was applied, for three cycles each, in flexion-extension (FE), lateral bending (LB), and axial rotation (AR). Data results were obtained from the third cycle. ResultsThe IPS-L construct significantly reduced the range of motion (ROM) by 75% in FE, 70% in LB, and 57% in AR, compared with intact. Lateral integrated plate-spacer demonstrated similar biomechanical stability as LS+LP, and higher stability than the LS-alone construct, but the difference was not statistically significant. ConclusionsThe IPS-L evaluated in the present study demonstrated equivalent biomechanical stability compared with standard lateral interbody fusion constructs. The addition of BPSs to the IPS-L showed significant reduction in ROM in FE, and the addition of BFSs showed significant reduction in ROM in FE and AR, compared with the integrated plate-spacer alone construct. The IPS-L with supplemental fixation may be a viable option for lateral interbody fusion. Long-term clinical studies are further required to confirm these results.

Gait abnormality due to spinal instability after lumbar facetectomy in the rat

Spinal instability of the lumbar spine causes various clinical symptoms. Among them, spinal instability is thought to contribute to low back pain, but the pathophysiological mechanisms are controversial. Although experimental animal models of spinal instability have been reported, it is unknown whether these models produce pain and whether spinal instability affects walking ability. We used the CatWalk system to investigate whether lumbar facetectomy causes gait abnormalities and low back pain. Thirty male Sprague-Dawley rats were divided into three experimental groups. In the sham group, only the bilateral L4-L5 facet joints were exposed. In the experimental group, rats underwent complete resection of the bilateral L4-L5 facet joints without neural tissue injury. The control group comprised naïve rats. The CatWalk system was used to analyze gait in postoperative weeks 3, 4.5, 6, and 7. Radiological and histological analyses were also performed. At 7 weeks postoperatively, the rats in the experimental group showed the gait abnormalities seen in low back pain and neuropathic pain models. Radiological examination of the same rats revealed spinal instability with histological evidence of intervertebral disc degeneration. These results suggest that spinal instability and/or intervertebral disc degeneration induce gait abnormalities and low back pain. This experimental model may be useful for elucidating the mechanisms underlying clinical symptoms, such as low back pain, in patients with spinal instability.

Traumatic atlantoaxial rotatory subluxation with bilateral locked cervical facets

A 70-year-old man was presented with a posterior neck pain and limitation of motion of cervical spine after a traffic accident. He had no neurologic deficit. Plain radiographs demonstrated torticollis and a typical “cock robin” position of the head (Fig. 1). Computed tomography showed atlantoaxial rotatory subluxation with bilateral locked facets (Fig. 2). Management consisted of analgesia, sedation, and application of halo skull traction. A clinical reduction of the subluxation was obtained and was confirmed by computed tomography scan. Immobilization with a rigid collar was performed in the following 8 weeks. The further follow-up of 6 months was completed; he was free from the neck pain and resumed normal activities. Fig. 2Atlantoaxial computed tomography scan (Top) and coronal reconstruction (Bottom). Bilateral facets between C1 and C2 are interlocking. View Large Image Figure Viewer Download Hi-res image