The Influence of Arthroscopic Menlsectomy and Post surgical Transcutaneous Electrical Nerve Stimulation on Quadriceps Strength and Motor Unit Activation

Abstract

Reflex inhibition of the quadriceps muscle group is a frequent and significant consequence of knee trauma, disease and surgical insult. The resultant quadriceps atrophy can be expected to delay rehabilitation and render the joint vulnerable to repeated injury resulting in capsular and synovial thickening, effusion and pain. A major purpose of this study was to examine the degree of quadriceps inhibition experienced by patients who undergo arthroscopic menisectomy. A secondary goal of this study was to investigate the efficacy of transcutaneous electrical nerve stimulation on the relief of reflex inhibition. Tests were performed on 12 patients prior to, and on day 1 and day 2 post surgery. True and placebo treatments of transcutaneous electrical nerve stimulation were administered on day 1 and day 2 post surgery. Measurements were made on the injured and normal limb with the knee fixed at 38G of flexion. Motor unit activation was determined by the twitch interpolation technique. Reduced motor unit activation was considered indicative of quadriceps reflex inhibition. Testing demonstrated that at all times the injured leg was weaker than the normal leg (p=.OOl). Following surgery, strength of the injured limb was significantly less than its pre operative score (p=.Ol). No significant recovery of strength was observed during the first two days following surgery. Injured legs were characterized by significantly lower motor unit activation at all times of testing Cp=.003). Following surgery, motor unit activation for the injured leg was significantly lower than its pre operative value (p=.Ol). By day 2 post surgery, motor unit activation had recovered Cp=.05) and was similar to the pre operative values for that leg. Transcutaneous electrical nerve stimulation had no effect on strength or motor unit activation. Recovery following arthroscopic surgery is characterized by an initial loss of strength and motor unit activation. By day 2, isometric strength remains depressed, however motor unit activation returns to pre surgery levels.