Strengthening exercises of the quadriceps femoris muscle (QFM) are of benefit for persons with knee osteoarthritis (OA). Studies reporting short-term effects of neuromuscular electrical stimulation (NMES) of the QFM in this population support the application of this modality as an adjunct treatment. The goals of this follow-up study are to compare the effects of an exercise program with and without NMES of the QFM on pain, functional performance, and muscle strength immediately posttreatment and 12 weeks following completion of the intervention. Sixty-three participants with knee OA were placed at random into two groups receiving 12 biweekly treatments: An exercise-only program or an exercise program combined with NMES. A significantly larger reduction in knee pain was seen immediately following treatment in the NMES group, which was maintained 12 weeks post-intervention in both groups. Although at this stage NMES had no additional effect, both groups demonstrated an immediate increase in muscle strength and in functional abilities, with no differences between groups. Although the improvements in gait velocity and in self-report functional ability were maintained at the follow-up session, the noted improvements in muscle strength, time to up and go, and stair negotiation were not maintained.
The study found that supplementing an exercise program with NMES to the QFM increased pain modulation immediately after treatment in patients with knee OA. Maintenance of the positive effects after conclusion of treatment during a 12-week period was observed only for pain, self-reported functional ability, and walk velocity, without any difference between groups.