Dynamic Stabilization for Degenerative Lumbar Scoliosis in Elderly Patients

Study Design. A retrospective study. Objective. To analyze outcomes after dynamic stabilization without fusion in degenerative lumbar scoliosis in elderly patients. Summary of Background Data. Frequent complications of posterolateral instrumented fusion have been reported after treatment of degenerative lumbar scoliosis in elderly patients. The use of dynamic stabilization without fusion can be advocated to reduce such adverse effects, being less invasive, with shorter operation time and less blood loss. No study in the literature has analyzed outcomes of dynamic stabilization without fusion in these degenerative deformities. Methods. Twenty-nine elderly patients (average age, 68.5 years; range, 61-78) with degenerative lumbar scoliosis, undergoing dynamic stabilization (Dynesys system) without fusion combined with decompressive laminectomy, in cases with associated stenosis, were analyzed. Stenosis of the vertebral canal was associated in 27 patients (93.1%); 13 cases (44.8%) also presented a degenerative spondylolisthesis. An independent spine surgeon retrospectively reviewed all the patients' medical records and radiographs to assess operative data and surgery-related complications. Preoperative, postoperative, and follow-up questionnaires were obtained to evaluate clinical outcomes. Results. The mean follow-up time was 54 months (range, 39-68). Oswestry Disability Index, Roland Morris Disability Questionnaire, and back pain and leg pain visual analogue scale scores received a statistically significant improvement at last control; the mean improvement was 51.6% for Oswestry Disability Index (P = 0.01), 58.2% for Roland Morris Disability Questionnaire (P = 0.01), 51.7% for leg pain (P = 0.02), and 57.8% for back pain (P = 0.01). Radiographically, degenerative scoliosis and associated spondylolisthesis resulted stable at follow-up with a moderate correction: the average scoliosis Cobb angle was 16.9 degrees (range, 12 degrees-37 degrees) before surgery and 11.1 degrees (range, 4 degrees-26 degrees) at last follow-up, with a 37.5% mean correction (P = 0.01); the anterior vertebral translation was 18.9% (range, 12%-27%) before surgery and 17% (range, 0%-27%) at follow-up, for a 14.6% mean correction (range, 0%-100%) (P = 0.02). No implant-related complications (screw loosening or breakage) or loss of correction were observed. Four cases (13.8%) presented an asymptomatic radiolucent line around screws of the S1 level without screw loosening. Six patients (20.7%) showed minor complications (ileus in 2 cases, urinary tract infection in 2, transient postoperative delirium in one, and respiratory difficulties after surgery in another patient). In 2 other patients (6.8%) incurred major complications, both requiring a revision surgery, for a misplaced screw on L5 and junctional disc degeneration at the lower level respectively. No neurologic complications occurred. Conclusion. Dynamic stabilization with pedicle screws in addition to decompressive laminectomy resulted a safe procedure in elderly patients with degenerative lumbar scoliosis; it was able to maintain enough stability to prevent progression of scoliosis and instability, enabling a wide laminectomy in cases of associated lumbar stenosis. This nonfusion stabilization technique was less aggressive than instrumented fusion and obtained a statistically significant improvement of the clinical outcome at last follow-up.