NFlex Dynamic Stabilization System : Two-Year Clinical Outcomes of Multi-Center Study

OBJECTIVE: Pedicle-based dynamic stabilization systems, in which semi-rigid rods or cords are used to restrict or control spinal segmental motion, aim to reduce or eliminate the drawbacks associated with rigid fusion. In this study, we analyzed the two-year clinical outcomes of patients treated with the NFlex (Synthes Spine, Inc.), a pedicle-based dynamic stabilization system. METHODS: Five sites participated in a retrospective study of 72 consecutive patients who underwent NFlex stabilization. Of these 72 patients, 65 were available for 2-year follow-up. Patients were included based on the presence of degenerative disc disease (29 patients), degenerative spondylolisthesis (16 patients), lumbar stenosis (9 patients), adjacent segment degeneration (6 patients), and degenerative lumbar scoliosis (5 patients). The clinical outcome measures at each assessment were Visual Analogue Scale (VAS) to measure back pain, and Oswestry Disability Index (ODI) to measure functional status. Radiographic assessments included evidence of instrumentation failure or screw loosening. RESULTS: Sixty-five patients (26 men and 39 women) with a mean age of 54.5 years were included. Mean follow-up was 25.6 months. The mean VAS score improved from 8.1 preoperatively to 3.8 postoperatively, representing a 53% improvement, and the ODI score from 44.5 to 21.8, representing a 51% improvement. Improvements in pain and disability scores were statistically significant. Three implant-related complications were observed. CONCLUSION: Posterior pedicle-based dynamic stabilization using the NFlex system seems effective in improving pain and functional scores, with sustained clinical improvement after two years. With appropriate patient selection, it may be considered an effective alternative to rigid fusion.

Change of Lumbar Motion after Multi-Level Posterior Dynamic Stabilization with Bioflex System : 1 Year Follow Up

OBJECTIVE: This study examined the change of range of motion (ROM) at the segments within the dynamic posterior stabilization, segments above and below the system, the clinical course and analyzed the factors influencing them. METHODS: This study included a consecutive 27 patients who underwent one-level to three-level dynamic stabilization with Bioflex system at our institute. All of these patients with degenerative disc disease underwent decompressive laminectomy with/without discectomy and dynamic stabilization with Bioflex system at the laminectomy level without fusion. Visual analogue scale (VAS) scores for back and leg pain, whole lumbar lordosis (from L1 to S1), ROMs from preoperative, immediate postoperative, 1.5, 3, 6, 12 months at whole lumbar (from L1 to S1), each instrumented levels, and one segment above and below this instrumentation were evaluated. RESULTS: VAS scores for leg and back pain decreased significantly throughout the whole study period. Whole lumbar lordosis remained within preoperative range, ROM of whole lumbar and instrumented levels showed a significant decrease. ROM of one level upper and lower to the instrumentation increased, but statistically invalid. There were also 5 cases of complications related with the fixation system. CONCLUSION: Bioflex posterior dynamic stabilization system supports operation-induced unstable, destroyed segments and assists in physiological motion and stabilization at the instrumented level, decrease back and leg pain, maintain preoperative lumbar lordotic angle and reduce ROM of whole lumbar and instrumented segments. Prevention of adjacent segment degeneration and complication rates are something to be reconsidered through longer follow up period.

Posterior Dynamic Stabilization with Selective Wide Decompression for Multilevel Lumbar Stenosis: Preliminary Result / 대한척추외과학회지

STUDY DESIGN: A prospective study OBJECTIVES: We wanted to assess the clinical outcomes of posterior dynamic stabilization with selective wide decompression for treating multilevel lumbar stenosis in old age. SUMMARY OF THE LITERATURE REVIEW: Deciding on the segments to be operated on is challenging problem for old age patients with multilevel lumbar stenosis. There have been no reports on posterior dynamic stabilization with selective wide decompression for treating multilevel lumbar stenosis. MATERIALS AND METHODS: We evaluated 18 patients who underwent posterior dynamic stabilization with selective decompression for multilevel disc degeneration and spinal stenosis. The mean age was 70.2 years and mean follow-up was 15.1 months. We evaluated the segmental angle, the range of motion (ROM) and pedicle screw loosening. The clinical results were evaluated according to the operative time, blood loss, the visual analogue scale (VAS) for the back pain and leg pain and and the Oswestry disability index (ODI). RESULTS: The mean number of operated segments was 2.16. The lordosis of the lumbar and operated segments showed no significant difference. However, the ROM of the total lumbar spine and the operation segment was significantly decreased from 36.8 to 24.3 and 22.9 to 13.1, respectively. The ROM for the adjacent segment did not show a significant difference. A radiolucent line around the pedicle screw appeared at 22 screws (19.3%) out of a total 114 screws. The VAS for back and leg pain were improved from 7.5 and 8.6 to 2.3 and 2.1, respectively. The ODI was improved from 41.5 to 13.4. CONCLUSIONS: The initial clinical outcomes were favorable after posterior dynamic stabilization with selective decompression. This procedure could be considered to be a useful option for treating multilevel stenosis in old age patients.

Late Complications of the Single Level 'Interspinous U' in Lumbar Spinal Stenosis with Mild Segmental Instability

OBJECTIVE: Decompression and/or fusion have traditionally been used to treat the spinal stenosis and spondylosis. Recently, several devices for dynamic posterior stabilization have been developed in treatment of lumbar spinal stenosis and degenerative spine diseases. This special technique of dynamic posterior stabilization of the lumbar spine may be defined as a system that would alter favorably the movement and load transmission of a spinal motion segment, without the fusion. At present, the 'interspinous U' has been using as one of favor device for dynamic posterior stabilization. METHODS: From January 2003 to November 2004, we have used the 'interspinous U' for 48 patients with lumbar spinal stenosis with mild segmental instability, after bilateral foraminotomy. All patients were checked the follow-up simple X-ray stress view after more than 12 months and evaluated the stability and the outcome of the patients. RESULTS: The patients were consisted of 26 men and 22 women, and mean ages was 55.3 years. The average follow- up period was approximately 22 months. The clinical outcomes were evaluated as excellent 15, good 19, fair 12 and poor 2. Especially, the patient group of unsatisfactory outcome(fair and poor) mainly complained the sudden burst back pain with the position change and this symptom was aggravated more and more during follow-up periods. In the flexion/extension lateral X-ray view, the evidence of bony absorption of the spinous process at the contacting side with 'interspinous U' device was found in 15 cases and also the minor instability was seen. CONCLUSION: 'interspinous U' is harder than any other ones for dynamic posterior stabilization, it is difficult to act like the "shock-absorber" and so the power to clamp the spinous process might be weak in spacer. Our preliminary results suggest that the late complications of the 'interspinous U' device in posterior dynamic stabilization may be the bone absorption of spinous process and minor instability, that is bone-implant interface failure.