Dynamic stabilization for degenerative spondylolisthesis: Evaluation of radiographic and clinical outcomes

Objective: To evaluate the dynamic stabilization system in degenerative lumbar spondylolisthesis. Methods: This retrospective study included 38 patients (mean age 63.7 years) with one- or two-level lumbar spinal stenosis who underwent laminectomy and Dynesys (Zimmer Spine, Minneapolis) stabilization. Pre-operatively, 24 had degenerative spondylolisthesis while the other 14 did not. Radiographic and clinical evaluations were analyzed with a mean follow-up of 41.4 +/- 6.9 (30-58) months. Results: The mean range of motion (ROM) at the index level was significantly reduced post-operation (10.0 +/- 3.3 degrees to 2.7 +/- 1.5 degrees, P<0.001). Screw loosening occurred in 13.3% of levels, 21.1% of patients, and 4.6% of screws. There were no differences between patients with and without spondylolisthesis in ROM and screw loosening. Overall, the mean Visual Analogue Scale (VAS) of back and leg pain improved significantly (6.0 +/- 3.2 to 1.9 +/- 2.6 and 7.4 +/- 2.6 to 2.5 +/- 2.9, both P < 0.001, respectively), and the Oswestry Disability Index (ODI) also improved significantly (50.6 +/- 19.5 to 27.3 +/- 24.9, P < 0.001) after the operation. Moreover, there were no differences between the groups of spondylolisthesis and non-spondylolisthesis, or among the patients with and without screw loosening. Conclusions: There is significant clinical improvement after laminectomy and dynamic stabilization with Dynesys for lumbar spinal stenosis. While there was restriction (<3 degrees) in segmental ROM, Dynesys provides similar radiographic stability and clinical effects regardless of pre-operative spondylolisthesis. (C) 2012 Elsevier B.V. All rights reserved.