Does Navigation Improve Accuracy of Placement of Pedicle Screws in Single-level Lumbar Degenerative Spondylolisthesis?: A Comparison Between Free-hand and Three-dimensional O-Arm Navigation Techniques.

STUDY DESIGN: This was a prospective, nonrandomized study. OBJECTIVES: To assess the accuracy of O-arm navigation-based pedicle screw insertion in lumbar degenerative spondylolisthesis and to compare it with free-hand pedicle screw insertion technique in matched population. SUMMARY OF BACKGROUND DATA: O-arm navigation is latest in navigation technology that can provide real-time intraoperative images in 3 dimensions while placing the pedicle screws to improve intraoperative pedicle screw accuracy. Degenerative lumbar spondylolisthesis is a locally unstable pathology and placement of pedicle screws can cause increased rotation and translation of the vertebral body. However, is this motion detected by the tracker placed across the unstable segment, is a matter of debate. Inability to detect these positional changes can lead to pedicle perforation while inserting screws using navigation. No study has evaluated the role of O-arm navigation in this patient population. MATERIALS AND METHODS: The study population was divided into 2 groups with 19 patients each, one comprising patients who underwent O-arm navigation-based pedicle screw insertion (group 1) and the other comprising patients who underwent free-hand pedicle screw insertion technique (group 2). A total of 152 pedicle screws were implanted in 38 patients for 1-level instrumented fusion for degenerative lumbar spondylolisthesis. Intraoperative 3-dimensional computed tomography scans using the O-arm were obtained for all patients after insertion of pedicle screws. The images were reviewed intraoperatively and postoperatively for the analysis of pedicle breaches. Assessments in either of the group included (i) accuracy of placement of screws; (ii) the rate and direction of perforation; and (iii) the number of segments the perforated screw was away from the navigation tracker. RESULTS: Mean age of patients in group 1 (O-arm navigation-assisted) was 60 years (SD 11.25; range, 37-73 y), whereas in group 2 (free-hand pedicle screw) was 62 years (SD 18.07; range, 36-90 y). Overall anatomic perforation rate was 12.5% (19/152). Individually, group 1 had 14.47% (11/76) of perforations in comparison with 10.53% (8/76) observed in group 2. The difference was not statistically significant. The lateral margin was the most common site of perforation in both group 1 (64%, 7/11) and group 2 (62.5%, 5/8). Functional perforation rate for the series was 3.3% (5/152), with group 1 having 2.63% (2/76) and group 2 having 3.95% (3/76). The rate of perforation (PR) was significantly higher statistically when the tracker was placed 3 or more [PR 37.5% (6/16)] spinal segments away from instrumented segment compared with when it was placed 1 (0%) or 2 [PR 13.89% (5/36)] spinal segments away. Overall, 11 screws (11/152, 7.24%) had grade 2 perforations and had to be revised. No neurological complications were observed in the series. CONCLUSIONS: O-arm navigation does not provide any significant advantage over conventional free-hand pedicle screw insertion technique in patients with single-level degenerative spondylolisthesis. The accuracy is dependent on the distance of the tracker from the level of instrumentation. Lateral perforations are more common because of instability at the instrumented level leading to translation and rotation of the vertebral body while placing pedicle screws leading to preferential lateral trajectory. These lateral perforations could not be prevented by using navigation. However, no significant complications were noted in either technique.

Minimally invasive compared with open lumbar laminotomy: no functional benefits at 6 or 24 months after surgery.

BACKGROUND CONTEXT: Comparative studies between open and minimally invasive surgical (MIS) approaches for the treatment of spinal stenosis have mainly investigated immediate postoperative parameters. PURPOSE: We aimed to compare the postoperative improvements in functional and pain scores between open versus MIS lumbar laminotomy and to describe the complications of each method. STUDY DESIGN/SETTING: We conducted as retrospective review of prospectively collected data. PATIENT SAMPLE: We included 113 patients. OUTCOME MEASURES: Visual analog scale for back and leg pain, Oswestry Disability Index (ODI), the North American Spine Society score on neurogenic symptoms (NS), and average Short Form Health Survey-36 (SF-36) score. Accidental durotomies and patients with reoperations are presented. METHODS: We obtained a list of patients who underwent either MIS or open unilateral one-level lumbar laminotomy for the treatment of neural foraminal or lateral recess stenosis with unilateral leg NS. Outcome measures are presented at 6 and 24 months postoperatively. RESULTS: From 2000 to 2008, 113 patients (30 open, 83 MIS) underwent a one-level lumbar laminotomy and had complete postoperative data available for analysis. Between the approaches, there were no differences in baseline demographic data or functional scores. At 6 and 24 months after surgery, there were no differences in improvement in back or leg pain, or improvement in ODI, NS, or SF-36 scores. The MIS group reported greater satisfaction with treatment at 6 months (p=.009) but not at 24 months. Within the MIS group, three patients (3.6%) experienced an inadvertent durotomy and two patients (2.4%) underwent fusion of the operated segment within 24 months. CONCLUSIONS: Compared with an open approach, MIS lumbar laminotomy gave no clear advantages in longer term functional or pain scores. The MIS group also had patients with inadvertent durotomies and reoperation within 2 years. In any lumbar decompressive surgery, the purported advantages of an MIS approach should be carefully weighed against potential complications. For a relatively simple surgery such as laminotomy, the open approach remains a safe and straightforward option.

Management of the neglected and healed bilateral cervical facet dislocation.

INTRODUCTION: There is limited literature on the management of neglected healed (fused) bilateral cervical facet dislocation. The authors report a case of a middle aged male who developed a bilateral facet dislocation but only sought treatment 14 months post injury when he experienced pain and deformity in the cervical spine. CASE REPORT: A 42-year-old male was pushed into a 1.2-m pool by accident and hit his head on the bottom. He immediately felt a sharp pain in his neck but was able to get out of the pool by himself and at the emergency department was found to have no neurological deficit. Standard trauma radiographs were performed and a grade 1 anterolisthesis of C4 on C5 was observed without any facet subluxation or dislocation. An emergent Magnetic Resonance Imaging (MRI) of the cervical spine confirmed X-ray results and in addition demonstrated injury to the posterior ligament complex and a broad-based posterior disc bulge. Computed Tomography (CT) scans revealed no facet dislocation or fractures. Unfortunately, the patient failed to come for his follow-up visits and at 14 months post injury, represented with pain and deformity with impairment of horizontal gaze. Computed tomography and MRI demonstrated a fused (bony) bilateral facet dislocation at C4/5. A cervical spine reconstruction consisting of a posterior-anterior-posterior approach was performed to address both the deformity and the pain. At 32-month follow-up, the patient remains well with no neurological symptoms, minimal neck pain and successful fusion. CONCLUSION: Current literature does not offer a clear solution to the management of healed neglected bilateral cervical facet dislocation. The presence of circumferential bony fusion around the deformity necessitates a posterior and anterior release and subsequent stabilization to address this complex problem. We also wish to highlight the order of the reconstructive approach and the need to recognize instability of the cervical spine despite normal CT scans in order to prevent late deformity.

Levetiracetam Differentially Alters CD95 Expression of Neuronal Cells and the Mitochondrial Membrane Potential of Immune and Neuronal Cells in vitro.

Epilepsy is a neurological seizure disorder that affects over 100 million people worldwide. Levetiracetam, either alone, as monotherapy, or as adjunctive treatment, is widely used to control certain types of seizures. Despite its increasing popularity as a relatively safe and effective anti-convulsive treatment option, its mechanism(s) of action are poorly understood. Studies have suggested neuronal, glial, and immune mechanisms of action. Understanding the precise mechanisms of action of levetiracetam would be extremely beneficial in helping to understand the processes involved in seizure generation and epilepsy. Moreover, a full understanding of these mechanisms would help to create more efficacious treatments while minimizing side-effects. The current study examined the effects of levetiracetam on the mitochondrial membrane potential of neuronal and non-neuronal cells, in vitro, in order to determine if levetiracetam influences metabolic processes in these cell types. In addition, this study sought to address possible immune-mediated mechanisms by determining if levetiracetam alters the expression of immune receptor-ligand pairs. The results show that levetiracetam induces expression of CD95 and CD178 on NGF-treated C17.2 neuronal cells. The results also show that levetiracetam increases mitochondrial membrane potential on C17.2 neuronal cells in the presence of nerve growth factor. In contrast, levetiracetam decreases the mitochondrial membrane potential of splenocytes and this effect was dependent on intact invariant chain, thus implicating immune cell interactions. These results suggest that both neuronal and non-neuronal anti-epileptic activities of levetiracetam involve control over energy metabolism, more specifically, mΔΨ. Future studies are needed to further investigate this potential mechanism of action.

Surgically treated cervical myelopathy: a functional outcome comparison study between multilevel anterior cervical decompression fusion with instrumentation and posterior laminoplasty.

BACKGROUND CONTEXT: Multilevel cervical myelopathy can be treated with anterior cervical discectomy and fusion (ACDF) or corpectomy via the anterior approach and laminoplasty via the posterior approach. Till date, there is no proven superior approach. PURPOSE: To elucidate any potential advantage of one approach over the other with regard to clinical midterm outcomes in this study. STUDY DESIGN: A prospective, 2-year follow-up of patients with cervical myelopathy treated with multilevel anterior cervical decompression fusion and plating and posterior laminoplasty. PATIENT SAMPLE: In total, 116 patients were studied. Sixty-four patients underwent ACDF two levels and above or anterior cervical corpectomy and fusion one level and above. Fifty-two patients underwent posterior cervical surgery (laminoplasty C3-C6 and C3-C7). OUTCOME MEASURES: Self-report measures: Japan Orthopedic Association (JOA) score, JOA recovery rate, visual analog scale for neck pain (VASNP), neck disability index (NDI), and American Academy of Orthopaedic Surgeons (AAOS) neurogenic symptom score (AAOS-NSS). Physiologic measures: range of motion (ROM) flexion and extension of neck. Functional measures: short-form 36 (SF-36) score comprising physical functioning, physical role function, bodily pain, general health, vitality, social role function, emotional role function, and mental health scales. METHODS: Comparison of the JOA scores, JOA recovery rates, NDI scores, SF-36 scores, VASNP, and ROM preoperatively to 2 years. Chi-square and two-sided Student t tests were used to analyze the variables. RESULTS: Posterior surgery took an hour shorter (p<.05) and had better improvement in JOA scores at early follow-up of 6 months (p=.025). Anterior surgery group had better improvement of NDI scores at early follow-up of 6 months (p=.024) and was associated with less blood loss intraoperatively compared with posterior surgery. There was no statistical difference between the two groups for JOA scores, JOA recovery rates, SF-36 quality-of-life scores, NDI, AAOS-NSS, VAS neck pain, and ROM at 2 years. Complications were higher for anterior surgery group: two hematoma postoperation, one vocal cord paresis, and one new onset C6/C7 dermatome numbness versus one dura leak in posterior surgery group. CONCLUSIONS: Our study showed that patients with multilevel disease treated with laminoplasty do well and compare favorably with patients treated with an anterior approach. Notably, posterior surgery was associated with shorter operating time, better improvement in JOA scores at 6 months, and a tendency toward lesser complications. Posterior surgery was not associated with increased neck disability and neck pain at 2 years. Anterior surgery had better NDI improvement at early follow-up. There is a need for a larger study that is prospectively randomized with long-term follow-up before we can confidently advocate one approach over the other in the management of cervical myelopathy.

Spontaneous cervical spinal epidural hematoma in the postpartum period.

STUDY DESIGN: We present the case study of a 31-year-old lady who had a spontaneous cervical spinal epidural hematoma in the postpartum period and who presented with sudden onset of neck pain and lower limb weakness for which an emergency decompressive laminectomy was performed with neurological recovery. OBJECTIVE: To report on the spontaneous spinal epidural hematoma in the postpartum period, which is a rare complication during pregnancy and requires early recognition and expedient intervention to prevent permanent neurological sequelae. SUMMARY OF BACKGROUND DATA: This complication has been described only once previously in the postpartum period. The recovery of the patient described here highlights the importance of early recognition and surgical intervention. METHODS: A case report of a spontaneous cervical spinal epidural haematoma in the postpartum period is presented and the pertinent literature is then reviewed. RESULTS: The patient had neurological recovery at 1-year follow-up, although she required clean intermittent self-catheterization once daily for bladder dysfunction. CONCLUSION: Early recognition and intervention for our patient allowed for neurological recovery with a spontaneous cervical spinal epidural hematoma in the postpartum period.

Predictors of survival in surgically treated patients of spinal metastasis.

BACKGROUND: The spinal metastasis occurs in up to 40% of cancer patient. We compared the Tokuhashi and Tomita scoring systems, two commonly used scoring systems for prognosis in spinal metastases. We also assessed the different variables separately with respect to their value in predicting postsurgical life expectancy. Finally, we suggest criteria for selecting patients for surgery based on the postoperative survival pattern. MATERIALS AND METHODS: We retrospectively analyzed 102 patients who had been operated for metastatic disease of the spine. Predictive scoring was done according to the scoring systems proposed by Tokuhashi and Tomita. Overall survival was assessed using Kaplan-Meier survival analysis. Using the log rank test and Cox regression model we assessed the value of the individual components of each scoring system for predicting survival in these patients. RESULT: The factors that were most significantly associated with survival were the general condition score (Karnofsky Performance Scale) (P=.000, log rank test), metastasis to internal organs (P=.0002 log rank test), and number of extraspinal bone metastases (P=.0058). Type of primary tumor was not found to be significantly associated with survival according to the revised Tokuhashi scoring system (P=.9131, log rank test). Stepwise logistic regression revealed that the Tomita score correlated more closely with survival than the Tokuhashi score. CONCLUSION: The patient's performance status, extent of visceral metastasis, and extent of bone metastases are significant predictors of survival in patients with metastatic disease. Both revised Tokuhashi and Tomita scores were significantly correlated with survival. A revised Tokuhashi score of 7 or more and a Tomita score of 6 or less indicated >50% chance of surviving 6 months postoperatively. We recommend that the Tomita score be used for prognostication in patients who are contemplating surgery, as it is simpler to score and has a higher strength of correlation with survival than the Tokuhashi score.

Intermediate Results of the Prestige LP Cervical Disc Replacement: Clinical and Radiological Analysis With Minimum Two-Year Follow-up.

STUDY DESIGN: prospective study. OBJECTIVE: present results of Prestige LP artificial cervical disc replacement (ADR). SUMMARY OF BACKGROUND DATA: motion preservation with ADR can potentially reduce adjacent segment degeneration. METHODS.: Forty patients with 59 Prestige LP ADR were analyzed. Cervical range of motion, Neck Disability Index, Visual Analogue, Short Form-36, Modified American Academy of Orthopedic Surgeons, and Japanese Orthopedic Association scores and radiographs were evaluated. Clinical results were compared with anterior cervical discectomy and fusion. RESULTS: there were 21 females and 19 males. Mean age was 43.9 years. Mean follow-up was 2.9 years. Of the patients, 62.5% had single level replacement-mainly C56 level (56%); 52.5% had myelopathy and 47.5% radiculopathy; 50% of neural compression was due to herniated disc, 45% due to spondylosis, and 5% due to both. There was significant improvement in the American Academy of Orthopedic Surgeons and Visual Analogue scores (P < 0.05) at 6 months and 2 years. There was significant improvement in the Neck Disability Index from a mean of 42.2 preoperation to 16.4 at 6 months and 15.2 at 2 years (P < 0.05). The mean Japanese Orthopedic Association score improved significantly from 14.7 preoperation to 15.7 at 6 months and 15.6 at 2 years (P < 0.05). There was significant improvement in all aspects of the Short Form-36 scores except general health (P < 0.05) at 6 months and 2 years. There was no significant difference in the clinical outcomes between ADR and anterior cervical discectomy and fusion. Segmental alignment (mean 8°, 14°, and 13° lordotic at preoperation, 6 months, and 2 years postoperation, respectively) and global alignment (mean 15.7°, 16.2°, and 17.3° lordotic at preoperation, 6 months, and 2 years postoperation, respectively) were maintained. Dynamic radiographs showed significant segmental motion with a 6 month's mean motion of 11.1° and a 2-year mean motion of 13.9° (P < 0.05). CONCLUSION: prestige LP ADR showed significant improvement in clinical outcomes at 2 years. It restores segmental lordosis and preserves segmental motion up to 2 years postoperation.

Concurrent fractures of the hip and wrist: a matched analysis of elderly patients.

INTRODUCTION: Osteoporotic fractures involving the hip and wrist are common in the elderly. The incidence of coincident hip and wrist fractures in the same patient is small but may represent a unique subpopulation of elderly with osteoporotic fragility fractures and little information has been published about these patients. MATERIALS AND METHODS: We performed a retrospective review studying a series of 33 elderly patients who were admitted with concurrent hip and wrist fractures and matched them with patients of similar age, race, gender and co-morbidities with isolated hip fractures analysing their pre-morbid functional status, degree of osteoporosis by the Singh's index, length of stay and re-admission rate. RESULTS: In our cohort of 33 matched pairs, location of fall in the study group consisted of 21 at home and 26 in the control group. The median duration of stay in hospital was 23 days versus 18 days in the control group. Bone density assessment of our study group revealed 18 patients with severe osteoporosis with Singh's index and 21 severe osteoporosis in the control group. The 1-year re-admission rate for the patients in the study group was 7 and 12 in the control group. Ambulatory status at discharge in the study group was 12 and in the control group 21. DISCUSSION AND CONCLUSION: Our study population demonstrated a higher proportion of community ambulators with fewer 1-year re-admission rates and a high cervical:trochanteric ratio of 2.7, all of which signify that they belong to a physiologically younger and more active cohort than our control group of isolated hip fractures. Patients with concurrent hip and wrist fractures were not significantly more osteoporotic, and showed a trend toward longer stay in hospital and incurred a higher cost of stay. The confluent upper limb injury was the likely reason for their post-discharge impaired ambulatory status. The most common location of injury in both groups of patients is at home.

The effects of lentiviral gene therapy with bone morphogenetic protein-2-producing bone marrow cells on spinal fusion in rats.

STUDY DESIGN: Rat spinal fusion model. OBJECTIVE: This study aimed to assess the ability of rat bone marrow cells (RBMCs) transfected with bone morphogenetic protein (BMP)-2-containing lentivirus to induce a posterolateral spinal fusion in a rat model. SUMMARY OF BACKGROUND DATA: Spinal arthrodesis is a commonly performed spinal procedure and autograft remains the standard for achieving spinal fusion. However, its procurement is associated with significant morbidity, and the rate of pseudoarthrosis has been reported to be 5% to 43%. Nonunion frequently leads to an unsatisfactory resolution of clinical symptoms and usually results in high medical costs and morbidity as well as the need for additional surgeries. These problems have led surgeons to search for alternative solutions to stimulate bone formation. Recombinant BMPs have also been used successfully in clinical trials. However, large doses of BMPs were required to induce adequate bone repair. The development of a regional gene therapy may be a more efficient method to deliver proteins to a specific anatomic site. Furthermore, adeno-BMP-2-producing rat bone marrow-derived cells have been used successfully to induce posterior spinal fusion. Recently, lentiviral vectors on the basis of human immunodeficiency virus have been developed for gene therapy. Lentiviruses are capable of insertion into the host genome, ensuring a prolonged gene expression. However, safety issues are a major concern when adopting these vectors for clinical use. METHODS: In vitro study, we used RBMCs transfected with lentivirus vectors encoding BMP-2 (Lenti-BMP-2), RBMCs transfected with lentivirus vectors encoding the green fluorescent protein (GFP) (Lenti-GFP), and untransfected RBMCs; the latter 2 were used as controls. Alkaline phosphatase (ALP) staining and ALP activity were compared between the groups to assess the ability of the Lenti-BMP-2-transfected RBMCs to stimulate osteoblastic differentiation. In the rat posterolateral spine fusion model, the experimental study comprised 4 groups. Group 1 comprised 6 animals that were implanted with a collagen sponge containing 5 million RBMCs transfected with Lenti-BMP-2. Group 2 comprised 3 animals that were implanted with a collagen sponge containing 5 million RBMCs transfected with Lenti-GFP. Group 3 comprised 6 animals that were implanted with a collagen sponge containing 5 million untransfected RBMCs. Group 4 comprised 3 animals that were implanted with a collagen sponge alone. The rats were assessed by radiographs obtained at 4, 6, and 8 weeks. After death, their spines were explanted and assessed by manual palpation, high-resolution microcomputerized tomography, and histologic analysis. RESULTS: The ALP staining was significantly greater in the Lenti-BMP-2-transfected RBMCs than in the untransfected RBMCs and the Lenti-GFP-transfected RBMCs. The ALP activity was 3-fold greater in the Lenti-BMP-2-transfected RBMCs than in the untransfected RBMCs and the Lenti-GFP-transfected RBMCs. In the rat spine fusion model, radiographic evaluation, high-resolution microcomputerized tomography, and manual palpation revealed spinal fusion in all the rats in Group 1 at 8 weeks. Groups 2, 3, and 4 comprised the control group. None of the rats in the control group (0 of 12) developed fusion at L4-L5. CONCLUSIONS: The present study demonstrated that BMP-2-producing RBMCs, created through lentiviral gene transfer, induced sufficient spinal fusion. The use of lentiviral vectors that contain the cDNA for BMP-2 will be a novel and promising approach for a spinal fusion strategy.

Kinematic analysis of the relationship between the grade of disc degeneration and motion unit of the cervical spine.

STUDY DESIGN: Kinetic MRIs of cervical spines were obtained and analyzed according to the amount of motion and the degenerative grade of the intervertebral disc. OBJECTIVE: To define the relationship between the grade of disc degeneration and the motion unit of the cervical spine and elucidate changes in the role of each cervical spine unit during flexion-extension motion caused by degeneration. SUMMARY OF BACKGROUND DATA: Degenerative changes in the cervical disc occur with age. The correlation between the degree of cervical disc degeneration and extent of cervical spine mobility has not yet been determined. The effect of degeneration on the overall motion of the functional spinal unit also remains undefined. METHODS: We studied 164 patients with symptomatic neck pain. The cervical intervertebral discs were graded by spine surgeons according to the degenerative grading system (Grades I to V). All radiologic data from kinetic MRIs were recorded on a computer for subsequent measurements. All measurements and calculations for translational motion and angular variation of each segment were automatically performed by a computer analyzer. RESULTS: The translational motion in discs with Grade II degeneration (mild degeneration) increased to Grade III degeneration (higher degeneration). However, the translational motion and angular variation significantly decreased for the Grade V (severe degeneration). For patients with relatively low grades of degeneration, Grades I and II discs, the C4-C5 and C5-C6 segmental units contributed the majority of total angular mobility of the spine. However, for the severely degenerated segments, Grade V discs, the contributions of the C4-C5 and C5-C6 U significantly decreased. CONCLUSION: The changes that occur with disc degeneration progress from the normal state to an unstable phase with higher mobility and subsequently to an ankylosed stage. This study evaluated the contribution of different levels to the changes in overall motion that occur with degeneration.

Disc regeneration: a glimpse of the future.

The normal IVD clinically acts to support and dissipate loads while permitting multiaxial motions of the spine. Its demanding mechanical function is provided by a well-defined microstructural organization and biochemical composition. IVD degeneration is a complex process that disrupts this well-defined organization and biochemical balance. One hallmark of IVD degeneration is the loss of proteoglycan and water in the NP. Because of the central role of proteoglycans in the function of the IVD, restoration of normal proteoglycan production may be critical. Many different biological strategies have been developed, including the use of cells, scaffolds, and molecules. The molecules used to treat disc degeneration include anticatabolics and growth factors, which may influence the cell proliferation rate and phenotypic expression of the cells. Delivery of the molecules may include direct injection into the disc and also in vivo and ex vivo gene therapy using a viral vector. Although many of the in vitro and in vivo studies have exhibited promise in reversing the observed changes of disc degeneration, the unanswered question is whether these efforts will translate to the relief of patients' symptoms, the most common of which is back pain.