Reginald Davis

Decompression and Coflex interlaminar stabilization compared with decompression and instrumented spinal fusion for spinal stenosis and low-grade degenerative spondylolisthesis: two-year results from the prospective, randomized, multicenter, Food and Drug Administration Investigational Device Exemption trial.

Study Design. Prospective, randomized, multicenter, Food and Drug Administration Investigational Device Exemption trial. Objective. To evaluate the safety and efficacy of Coflex interlaminar stabilization compared with posterior spinal fusion in the treatment of 1- and 2-level spinal stenosis and degenerative spondylolisthesis. Summary of Background Data. Long-term untoward sequelae of lumbar fusion for stenosis and degenerative spondylolisthesis have led to the search for motion-preserving, less-invasive alternatives. Methods. Three hundred twenty-two patients (215 Coflex and 107 fusions) from 21 sites in the United States were enrolled between 2006 and 2010. Subjects were randomized to receive laminectomy and Coflex interlaminar stabilization or laminectomy and posterolateral spinal fusion with spinal instrumentation in a 2:1 ratio. Overall device success required a 15-point reduction in Oswestry Disability Index, no reoperations, no major device-related complications, and no postoperative epidural injections. Results. Patient follow-up at minimum 2 years was 95.3% and 97.2% in the Coflex and fusion control groups, respectively. Patients taking Coflex experienced significantly shorter operative times (P < 0.0001), blood loss (P < 0.0001), and length of stay (P < 0.0001). There was a trend toward greater improvement in mean Oswestry Disability Index scores in the Coflex cohort (P = 0.075). Both groups demonstrated significant improvement from baseline in all visual analogue scale back and leg parameters. Patients taking Coflex experienced greater improvement in Short-Form 12 physical health outcomes (P = 0.050) and equivalent mental health outcomes. Coflex subjects experienced significant improvement in all Zurich Claudication Questionnaire outcomes measures compared with fusion (symptom severity [P = 0.023]; physical function [P = 0.008]; satisfaction [P = 0.006]). Based on the Food and Drug Administration composite for overall success, 66.2% of Coflex and 57.7% of fusions succeeded (P = 0.999), thus demonstrating noninferiority. The overall adverse event rate was similar between the groups, but Coflex had a higher reoperation rate (10.7% vs. 7.5%, P = 0.426). At 2 years, fusions exhibited increased angulation (P = 0.002) and a trend toward increased translation (P = 0.083) at the superior adjacent level, whereas Coflex maintained normal operative and adjacent level motion. Conclusion. Coflex interlaminar stabilization is a safe and efficacious alternative, with certain advantages compared with lumbar spinal fusion in the treatment of spinal stenosis and low-grade spondylolisthesis. Level of Evidence: 1

Multi-center, prospective, randomized, controlled investigational device exemption clinical trial comparing Mobi-C Cervical Artificial Disc to anterior discectomy and fusion in the treatment of symptomatic degenerative disc disease in the cervical spine.

Background Anterior cervical discectomy and fusion (ACDF) is the gold standard for treating symptomatic cervical disc degeneration. Cervical total disc replacements (TDRs) have emerged as an alternative for some patients. The purpose of this study was to evaluate the safety and effectiveness of a new TDR device compared with ACDF for treating single-level cervical disc degeneration. Methods This was a prospective, randomized, controlled, multicenter Food and Drug Administration (FDA) regulated Investigational Device Exemption (IDE) study. A total of 245 patients were treated (164 TDR: 81 ACDF). The primary outcome measure was overall success based on improvement in Neck Disability Index (NDI), no subsequent surgical interventions, and no adverse events (AEs) classified as major complications. Secondary outcome measures included SF-12, visual analog scale (VAS) assessing neck and arm pain, patient satisfaction, radiographic range of motion, and adjacent level degeneration. Patients were evaluated preoperatively and postoperatively at 6 weeks, 3, 6, 12, 18, and 24 months. The hypothesis was that the TDR success rate was non-inferior to ACDF at 24 months. Results Overall success rates were 73.6% for TDR and 65.3% for ACDF, confirming non-inferiority (p < 0.0025). TDR demonstrated earlier improvements with significant differences in NDI scores at 6 weeks and 3 months, and VAS neck pain and SF-12 PCS scores at 6 weeks (p<0.05). Operative level range of motion in the TDR group was maintained throughout follow-up. Radiographic evidence of inferior adjacent segment degeneration was significantly greater with ACDF at 12 and 24 months (p < 0.05). AE rates were similar. Conclusions Mobi-C TDR is a safe and effective treatment for single-level disc degeneration, producing outcomes similar to ACDF with less adjacent segment degeneration. Level of Evidence: Level I. Clinical relevance: This study adds to the literature supporting cervical TDR as a viable option to ACDF in appropriately selected patients with disc degeneration.

Comparison of Clinical Outcomes of 1- and 2-Level Total Disc Replacement: Four-Year Results From a Prospective, Randomized, Controlled, Multicenter IDE Clinical Trial.

Study Design. A prospective, randomized, multicenter Food and Drug Administration Investigation Device Exemption study using total disc replacement as surgical treatment of degenerative disc disease at 1 or 2 contiguous levels of the cervical spine. Objective. To evaluate the safety and effectiveness of total disc replacement at single or 2 contiguous levels through 48 months of follow-up. Summary of Background Data. Cervical total disc replacement has been shown to be a safe and effective alternative to anterior cervical discectomy and fusion at 24 months. Its motion-preserving capabilities may avoid accelerating adjacent segment pathology and thereby lower the rate of associated complications. Methods. Patients were randomized in a 2:1 ratio (total disc replacement [TDR]: anterior cervical discectomy and fusion [ACDF]) at 24 sites. Ultimately, 164 patients received TDR at 1 level and 225 patients received TDR at 2 contiguous levels. An additional 24 patients (15 one-level, 9 two-level) were treated with TDR as training cases. Outcome measures included neck disability index, visual analogue scale neck and arm pain, Short Form 12-item Health Survey (SF-12) Mental Composite Score (MCS) and Physical Composite Score (PCS), range of motion, major complication rates, and secondary surgery rates. Patients received follow-up examinations at regular intervals through 4 years after surgery. Results. Preoperative characteristics were statistically similar for the 1- and 2-level patient groups. Four-year follow-up rates were 83.1% (1-level) and 89.0% (2-level). There was no statistically significant difference between 1- and 2-level TDR groups for all clinical outcome measures. Both TDR groups experienced significant improvement at each follow-up when compared with preoperative scores. One case of migration was reported in the 2-level TDR group. Conclusion. A 4-year post hoc comparison of 1- and 2-level TDR patients concurrently enrolled in a 24-center, Food and Drug Administration Investigation Device Exemption clinical trial indicated no statistical differences between groups in clinical outcomes, overall complication rates, and subsequent surgery rates. Level of Evidence: 1

Measurement Performance of a Computer Assisted Vertebral Motion Analysis System.

Background Segmental instability of the lumbar spine is a significant cost within the US health care system; however current thresholds for indication of radiographic instability are not well defined. Purpose To determine the performance measurements of sagittal lumbar intervertebral measurements using computerassisted measurements of the lumbar spine using motion sequences from a video-fluoroscopic technique. Study design Sensitivity, specificity, predictive values, prevalence, and test-retest reliability evaluation of digitized manual versus computer-assisted measurements of the lumbar spine. Patient sample A total of 2239 intervertebral levels from 509 symptomatic patients, and 287 intervertebral levels from 73 asymptomatic participants were retrospectively evaluated. Outcome measures Specificity, sensitivity, negative predictive value (NPV), diagnostic accuracy, and prevalence between the two measurement techniques; Measurements of Coefficient of repeatability (CR), limits of agreement (LOA), intraclass correlation coefficient (ICC; type 3,1), and standard error of measurement for both measurement techniques. Methods Asymptomatic individuals and symptomatic patients were all evaluated using both the Vertebral Motion Analysis (VMA) system and fluoroscopic flexion extension static radiographs (FE). The analysis was compared to known thresholds of 15% intervertebral translation (IVT, equivalent to 5.3mm assuming a 35mm vertebral body depth) and 25° intervertebral rotation (IVR). Results The VMA measurements demonstrated greater specificity, % change in sensitivity, NPV, prevalence, and reliability compared with FE for radiographic evidence of instability. Specificity was 99.4% and 99.1% in the VMA compared to 98.3% and 98.2% in the FE for IVR and IVT, respectively. Sensitivity in this study was 41.2% and 44.6% greater in the VMA compared to the FE for IVR and IVT, respectively. NPV was 91% and 88% in the VMA compared to 62% and 66% in the FE for IVR and IVT, respectively. Prevalence was 12.3% and 11.9% for the VMA compared to 6.1% and 5.4% for the FE in IVR and IVT, respectively. Intra-observer IVR and IVT had a CR of 2.49 and 2.62, respectively. Inter-observer IVR and IVT had a CR of 1.99 and 2.81, respectively. Intra-subject (test/retest) CR were 2.49 and 3.11 for IVR and IVT, respectively. Conclusions The VMA system showed greater measurement performance in the detection of radiographic instability compared with FE radiographs.

Variability in flexion extension radiographs of the lumbar spine: A comparison of uncontrolled and controlled bending

Background While low back pain is one of the most prevalent, if not the most prevalent reasons for visits to physicians, a majority of patients with low back pain cannot be given a definitive diagnosis. While there have been substantial advances in imaging technologies over the past 30 years, relatively little has changed in the methodologies for evaluating functionality of the lumbar spine. The current standard of care for function assessment of the lumbar spine focuses on uncontrolled patient directed motion which results in increased inter-patient variability. Recent advancements in functional lumbar spine testing utilize controlled bending and computerized imaging evaluation. Purpose To compare the measurement variability of lumbar spine motion when diagnosed using measurements of intervertebral motion taken from standard bending flexion/extension radiographs (FE) between uncontrolled and controlled motion. Study Design One-hundred nine patients (57 asymptomatic, 52 symptomatic) were consented in the prospective investigation. The research was designed to compare studies involving FE to controlled motion bending radiographs using the Vertebral Motion Analysis (VMA), (Ortho Kinematics, Inc) within the same patient. Each patient agreed to undergo fluoroscopic still imaging to capture FE data and to undergo cine fluoroscopic imaging to capture VMA data. Outcome Measures Measurement variability was determined by the mean and standard deviation of intervertebral rotation when evaluated by 5 independent observers evaluating each of the 109 patients FE and VMA. The resulting standard deviation of the intervertebral rotation determinations was used as the measure of variability. Methods The VMA measurements for assessing intervertebral motion were characterized by the use of: (1) a handling device that assists patients through a standard arc of lumbar bending in both an upright and recumbent posture (70 degree flexion/extension arcs; 60 degree left/right bending arcs); (2) video fluoroscopy imaging of the lumbar spine during bending (capturing images at 8 frames per second); and (3) image processing software capable of automatic frame-to-frame registration and tracking of vertebral bodies across the sequence of video-fluoroscopic images to derive measurements of intervertebral rotation and translation. The FE data were assessed from voluntary bending by the patient. Results There was statistical greater measurement variability in intervertebral rotation in FE when compared to VMA (both standing and lying). When comparing measurement variability between FE and VMA, results indicate between a 26% to 46% decrease in measurement variability under VMA compared to FE. These findings are consistent across asymptomatic and symptomatic patients. Conclusions The current standard of care for functional testing of the lumbar spine utilizes uncontrolled FE with a manual data evaluation process. Recent developments in using computerized imaging processes has improved, however there remains variability in patient bending due to the self-selected rate and position of the bending. VMA results in a significant reduction in measurement variability of intervertebral rotation measurements.

Return-to-Duty Rates Following Minimally Invasive Spine Surgery Performed on Active Duty Military Patients in an Ambulatory Surgery Center

Background Low back pain is a primary health care utilization driver in the US population. Health care evaluation visits for low back pain are as common as medical evaluation for the common cold. Low back pain is the most common reason for reductions in activities of daily living and work activity in the general population. Although these statistics are compelling, in the military population, there is arguably a significantly greater economic impact on the military population, as the cost to train, retain, and deploy a service member is a tremendous cost. Methods The current study retrospectively examines surgical outcomes, return to duty, and patient-centric outcomes among 82 active duty or reserve military patients who underwent an outpatient minimally invasive spine surgery Laminotomy Foraminotomy Decompression for the treatment of lumbar spinal stenosis in an ambulatory surgery center. Findings Overall, our results indicate that within the 82 active duty military service members, 100% of the service members return to duty within 3 mo. Additionally, there was a significant reduction in self-reported pain and disability 12 mo postoperative, whereas the average length of surgery was 62 min with an average estimated blood loss of 30.64 mL. Discussion The current study indicates that minimally invasive procedures for the treatment of lumbar spinal stenosis in an ambulatory surgery center setting are an effective option for active duty servicemen to reduce return-to-duty rates and symptomatic back-related pain and disability.