Effectiveness of electric stimulation of the vastus medialis muscle in the rehabilitation of patients after total knee arthroplasty

Objective: To investigate the possible effect of electric muscle stimulation (EMS) of the vastus medialis on the walking speed, Hospital for Special Surgery (HSS) knee score, and Physiological Cost Index (PCI) of patients during rehabilitation after total knee arthroplasty (TKA). Design: Prospective, randomized controlled trial. Setting: Various departments at a district general hospital in the United Kingdom. Participants: Thirty patients with unilateral osteoarthritis of the knee admitted for elective TKA were randomly assigned to 1 of 2 groups (15 per group): control and treatment. Both groups received standard physical therapy. The treatment group also received EMS of the vastus medialis. Intervention: EMS (40Hz, 300mus) of the vastus medialis muscle for 4 hours a day, starting on postoperative day 2, over the first 6 postoperative weeks. Main Outcome Measures: Changes in walking speed, HSS knee score, and effort of walking as measured by the PCI. Results: A statistically significant increase in walking speed was observed in the treatment group in relation to the control group at both 6 weeks (P=.0002) and 12 weeks (P<.0001) postoperatively. No statistically significant difference was observed in relation to the PCI or the HSS knee score variables. Conclusions: Application of EMS after TKA resulted in a statistically significant improvement in patients' walking speed. There was also a carry-over effect after the discontinuation of treatment.