Closed versus open partial meniscectomy: postoperative changes in the force-velocity relationship of muscle.

Abstract

This study compares the effects of closed and open partial meniscectomies on the in vivo force-velocity relationship of the knee extensors. One group of normal subjects (controls, N = 7) and two groups of patients (closed partial meniscectomy, N = 9; open partial men iscectomy, N = 6) participated in this study. Each volunteer was tested on three occasions (presurgery, 20 days postsurgery, and 42 days postsurgery) for maximal knee extension torque at 0, 48, 96, 144, and 192°/sec using an isokinetic dynamometer. Maximal knee extension torques were recorded at a specific joint angle (30° below the horizontal plane) for all test speeds. Presurgically, the injured leg exhibited a uni form impairment of approximately -20%. At 20 days postsurgery, a substantial difference was evident be tween the two groups of patients. For the closed group, the mean (±SE) impairment was -19.5 ± 2.2, -23.9 ± 2.8, -31.5 ± 4.0, -37.5 ± 5.3, and - 34.5 ± 6.1% at 0, 48, 96, 144, and 192°/sec, respectively. In contrast, the corresponding impairment for the open group was -34.9 ± 7.2, -47.7 ± 4.8, -57.5 ± 5.3, -57.0 ± 3.5, and -59.1 ± 3.2%. The impairment of both groups was speed-specific with the greatest deficits occurring at 192°/sec. At 42 days postsurgery, there were no sig nificant differences between the two groups of patients although the open group still demonstrated speed- specific impairment. These results demonstrate that the closed approach has less effect on functional pa rameters which are important to athletic competition.