Factors Affecting Segmental Motion of Lumbar Total Disc Replacement / 대한정형외과학회잡지

ABSTRACT

PURPOSE: To assess factors significantly affecting the range of motion of the lumbar spine at the operated segment following total disc replacement (TDR) arthroplasty. MATERIALS AND METHODS: Thirty-six patients (15 men and 21 women) who received lumbar TDR at a single level using Prodisc II (Spine Solutions Inc, New York, NY USA) were included in this study. The study included 23 cases at L4-5 and 13 cases at L5-S1. The average patient age was 43.6 years (range, 23-59 years) and the minimum follow-up was 24 months (range, 24-61 months). Two independent observers measured radiological parameters preoperatively, at 3 months postoperatively, and at the final follow-up. These parameters included disc height, affected level segmental range of motion (ROM) and prosthesis position and height. A radiologist independently measured facet joint degeneration and the fat contents of the paraspinal muscles on preoperative MR images. Clinical results were evaluated using the Oswestry Disability Index (ODI) and the Visual Analogue Scale (VAS). RESULTS: Segmental ROM was well preserved at the final follow-up (preoperative, 11.3 degrees; 3 months postoperative 13.2 degrees; final follow up, 13.1 degrees). The factors found to affect segmental ROM significantly at the final follow-up were the preoperative ROM, preoperative disc height, disc height increment ratio and a history of previous back surgery on the affected disc (p<0.05). The VAS significantly improved in patients with increased segmental ROM at the operated level (p<0.05). CONCLUSION: Statistical analysis showed that the factors affecting segmental ROM were the preoperative ROM, preoperative disc height, disc height increment ratio, and a history of previous back surgery on the affected disc. However, further effort needs to be directed towards an evaluation of a larger number of patients with a longer follow-up.