ISOKINETIC EVALUATION OF THE ANKLE BEFORE AND AFTER SURGICAL-TREATMENT OF THE LUMBAR DISC HERNIATION

Objective. To quantitatively evaluate the ankle strength before and af ter surgical treatment for herniated lumbar intervertebral disc. Desig n. Isokinetic test of ankle joint and statistical analysis were design ed to evaluate the results before and after surgery. Background. Asses sments of the results before and after treatment of lumbar herniation of intervertebral discs (HIVD) in previous papers were all based on pa tients' symptoms, activity, working condition, the angle of straight l eg raising test, and requirement of pain medication. We designed a pro spective study of isokinetic measurement of the ankle joints in those patients with HIVD to try to find a quantitative method of evaluation. Methods. The criteria of selecting patients were single level disc he rniation of lumbar spine, without associated major neuromuscular or mu sculoskeletal disorder, normal mental status and cooperative, clinical ly evident radiculopathy, failure of conservative treatment, and age u nder 45. The isokinetic strengths of the ankle joints, of both involve d and uninvolved limbs, were evaluated with plantarflexion or dorsifle xion, in the velocities of 30, 60, 120, and 180 degrees s(-1), accordi ng to their affected levels. Standard laminotomy with removal of inter vertebral disc was undertaken for all patients under general anesthesi a. The isokinetic strength of the ankle joints were evaluated with Kin -Com dynamometer before surgery, and post-operatively at 1 week, 2 wee ks, 4 weeks, 2 months, and 3 months. All data were collected and analy zed with linear mixed model for analysis of variance with repeated mea sures. Results. From January, 1996, 5 patients entered this study, 2 p atients were L4-L5 herniation, and 3 for L5-S1. The estimated mean str ength ratio and standard error was 55.04 +/- 2.21% preoperatively, 46. 42 +/- 2.22% postoperatively at 1 week, 64.35 +/- 2.23% postoperativel y at 2 weeks, 73.93 +/- 2.23% postoperatively at 4 weeks, 100.40 +/- 2 .22% postoperatively at 2 months, and 104.55 +/- 2.21% postoperatively at 3 months. Conclusions. In this preliminary prospective study, ther e seems no correlation between duration of the symptoms and isokinetic strength of the ankle joint. There is, however, marked improvement of isokinetic strength of ankle joint postoperatively at 2 months, which was statistically significant. Relevance In this research, isokinetic test of the ankle joint might be a parameter of functional outcome af ter treatment in those patients with lumbar HIVD, and the time of full y functional recovery of ankle joint after surgery is 2 months. (C) 19 98 Elsevier Science Ltd. All rights reserved.