Clinical and Radiological Outcome of an Interspinous Dynamic Stabilization System in Degenerative Lumbar Disease:24 Cases with Over 24 Months of Follow-up

ABSTRACT

OBJECTIVE: The purpose of this study was to analyze the clinical and radiological outcomes of dynamic stabilization with DIAM implants. METHODS: We evaluated 24 cases in which lumbar decompressive surgery was performed with dynamic stabilization using DIAM and having more than 24 months of follow up. Indications consisted of spinal stenosis with or without a herniated disc and transition level stenosis of the instrumented fusion segment. Operative data, clinical outcome, and plain and flexion/extension radiographs were obtained and compared to preoperative and postoperative data. RESULTS: The mean age at operation was 56.2 years(range 47-68); the mean follow-up duration was 28.4 months(range 24-37 months).The mean pain and function scores improved significantly from baseline to follow-up, as follows back pain VAS score from 6.2 to 2.5, leg pain VAS score from 7.2 to 2.4, and Prolo's economic and functional rating score from 5.8 to 8.2. Radiological data demonstrated that the heights of the intervertebral foramen and the posterior disc increased significantly after the procedure. There were no implant-associated complications except for two spinous process fractures which occurred during DIAM insertion, and one case of wound infection. Flexion instability and spondylolisthesis occurred in two cases during the follow-up period. CONCLUSION: These mid-term results suggest that DIAM is a safe and effective alternative surgical option in the treatment of degenerative lumbar stenosis without flexion instability. Careful follow-up is needed to watch for the development of flexion instability and spondylolisthesis.