Abstract
Current evidence on the indications for and efficacy of non-rigid lumbar stabilisation remains unclear. The aim of this study was to review the outcome of the DYNESYS system (Zimmer, Inc.) in a consecutive series of 34 patients undergoing this procedure between 2001 and 2006.
Prospectively collected outcome measure data obtained pre-operatively and at 1 year post-operatively was analysed using the Wilcoxon Signed Rank Test. Kaplan Meier survival analysis was performed using revision surgery as the end point. Cox Regression was utilised to identify variables that were related to implant survival.
Pain rating on the visual analogue scale improved from a mean of 7 pre-op to 4 at 1 year (p=0.009), Roland Morris Disability Questionnaire scores from 13 to 9 (p=0.02), Modified Somatic Perception Questionnaire from 13 to 9 (p=0.03). When reporting subjective outcome, 54% of patients reported “better” or “much better” outcomes at last followup (12–69 months post op). Eight patients (25%) required removal of the implant and conversion to fusion, one of whom had deep infection. Kaplan Meier survival analysis revealed a survival of 78% at 5 years (95% CI, 60 – 96%). Previous spinal surgery was significantly related to the time of survival of the implant (p=0.008).
Our study has demonstrated a high revision rate for this implant and 54% patient satisfaction. We recommend that patients be counseled regarding these risks and further use of this implant should be subject to the outcome of larger studies and randomised controlled trials.
Correspondence should be addressed to Editorial Secretary Mr ML Costa or Assistant Editorial Secretary Mr B.J. Ollivere at BOA, 35–43 Lincoln’s Inn Fields, London WC2A 3PE, England; Email: mattcosta@hotmail.com or ben@ollivere.co.uk
