Kent, Roland

Study Design: Prospective randomized Food and Drug Administration investigational device exemption clinical trial. Objective: The purpose of the present study is to report the 1-year clinical and radiographic outcomes and safety profile of patients who underwent lumbar facet arthroplasty through implantation of the Total Posterior Spine System (TOPS) device. Summary of Background Data: Lumbar facet arthroplasty is one proposed method of dynamic stabilization to treat grade-1 spondylolisthesis with stenosis; however, there are currently no Food and Drug Administration-approved devices for facet arthroplasty. Methods: Standard demographic information was collected for each patient. Radiographic parameters and patient-reported outcome measures were assessed preoperatively and at regular postoperative intervals. Complication and reoperation data were also collected for each patient. Results: At the time of this study, 153 patients had undergone implantation of the TOPS device. The mean surgical time was 187.8 minutes and the mean estimated blood loss was 205.7cc. The mean length of hospital stay was 3.0 days. Mean Oswestry Disability Index, Visual Analog Score leg and back, and Zurich Claudication Questionnaire scores improved significantly at all postoperative time points (P>0.001). There were no clinically significant changes in radiographic parameters, and all operative segments remained mobile at 1-year follow-up. Postoperative complications occurred in 11 patients out of the 153 patients (7.2%) who underwent implantation of the TOPS device. Nine patients (5.9%) underwent a total of 13 reoperations, 1 (0.6%) of which was for device-related failure owing to bilateral L5 pedicle screw loosening. Conclusions: Lumbar facet arthroplasty with the TOPS device demonstrated a statistically significant improvement in all patient-reported outcome measures and the ability to maintain motion at the index level while limiting sagittal translation with a low complication rate.

OBJECTIVE The purpose of this study was to evaluate the safety and efficacy of a posterior facet replacement device, the Total Posterior Spine (TOPS) System, for the treatment of one-level symptomatic lumbar stenosis with grade I degenerative spondylolisthesis. Posterior lumbar arthroplasty with facet replacement is a motion-preserving alternative to lumbar decompression and fusion. The authors report the preliminary results from the TOPS FDA investigational device exemption (IDE) trial. METHODS The study was a prospective, randomized controlled FDA IDE trial comparing the investigational TOPS device with transforaminal lumbar interbody fusion (TLIF) and pedicle screw fixation. The minimum follow-up duration was 24 months. Validated patient-reported outcome measures included the Oswestry Disability Index (ODI) and visual analog scale (VAS) for back and leg pain. The primary outcome was a composite measure of clinical success: 1) no reoperations, 2) no device breakage, 3) ODI reduction of ≥ 15 points, and 4) no new or worsening neurological deficit. Patients were considered a clinical success only if they met all four measures. Radiographic assessments were made by an independent core laboratory. RESULTS A total of 249 patients were evaluated (n = 170 in the TOPS group and n = 79 in the TLIF group). There were no statistically significant differences between implanted levels (L4–5: TOPS, 95% and TLIF, 95%) or blood loss. The overall composite measure for clinical success was statistically significantly higher in the TOPS group (85%) compared with the TLIF group (64%) (p = 0.0138). The percentage of patients reporting a minimum 15-point improvement in ODI showed a statistically significant difference (p = 0.037) favoring TOPS (93%) over TLIF (81%). There was no statistically significant difference between groups in the percentage of patients reporting a minimum 20-point improvement on VAS back pain (TOPS, 87%; TLIF, 64%) and leg pain (TOPS, 90%; TLIF, 88%) scores. The rate of surgical reintervention for facet replacement in the TOPS group (5.9%) was lower than the TLIF group (8.8%). The TOPS cohort demonstrated maintenance of flexion/extension range of motion from preoperatively (3.85°) to 24 months (3.86°). CONCLUSIONS This study demonstrates that posterior lumbar decompression and dynamic stabilization with the TOPS device is safe and efficacious in the treatment of lumbar stenosis with degenerative spondylolisthesis. Additionally, decompression and dynamic stabilization with the TOPS device maintains segmental motion.