Isokinetic evaluation of the ankle before and after surgical treatment of the lumbar disc herniation.

Abstract

OBJECTIVE: To quantitatively evaluate the ankle strength before and after surgical treatment for herniated lumbar intervertebral disc. DESIGN: Isokinetic test of ankle joint and statistical analysis were designed to evaluate the results before and after surgery. BACKGROUND: Assessments of the results before and after treatment of lumbar herniation of intervertebral discs (HIVD) in previous papers were all based on patients' symptoms, activity, working condition, the angle of straight leg raising test, and requirement of pain medication. We designed a prospective 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 herniation of lumber spine, without associated major neuromuscular or musculoskeletal disorder, normal mental status and cooperative, clinically evident radiculopathy, failure of conservative treatment, and age under 45. The isokinetic strengths of the ankle joints, of both involved and uninvolved limbs, were evaluated with plantarflexion or dorsiflexion, in the velocities of 30, 60, 120, and 180 degrees s(-1), according to their affected levels. Standard laminotomy with removal of intervertebral disc was undertaken for all patients under general anesthesia. The isokinetic strength of the ankle joints were evaluated with Kin-Com dynamometer before surgery, and post-operatively at 1 week, 2 weeks, 4 weeks, 2 months, and 3 months. All data were collected and analyzed with linear mixed model for analysis of variance with repeated measures. RESULTS: From January, 1996, 5 patients entered this study, 2 patients were L4-L5 herniation, and 3 for L5-S1. The estimated mean strength ratio and standard error was 55.04 +/- 2.21% preoperatively, 46.42 +/- 2.22% postoperatively at 1 week, 64.35 +/- 2.23% postoperatively 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, there 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.