A home-based protocol of electrical muscle stimulation for quadriceps muscle strength in older adults with osteoarthritis of the knee

Objective. To determine whether home-based neuromuscular electrical stimulation (NMES) applied to the quadriceps femoris (QF) muscle increases strength, physical activity, and physical performance in older adults with knee osteoarthritis (OA). Methods. Thirty-four adults (> 60 yrs) with radiographically confirmed symptomatic knee OA were randomized to NMES plus education or education only (EDU). The primary outcome was isometric QF peak torque (PT_ISO), with secondary outcomes of daily step counts, total activity vector magnitude, 100-foot walk-turn-walk, timed stair climb, chair rise, and pain. The NMES group used a portable electrical muscle stimulator 3 days a week for unilateral QF training with incremental increases in the intensity of isometric contraction to 30-40% of maximum over 12 weeks. Both groups received the 12-week Arthritis Self-Management course and were followed an additional 12 weeks. Results. The stimulated knee-extensor showed a 9.1% increase in 120° PT_ISO compared to a 7% loss in the EDU group (time × group interaction for 120° PT_ISO; p = 0.04). The chair rise time decreased by 11% in the NMES group, whereas the EDU group saw a 7% reduction (p = 0.01, time; p = 0.9, group). Similarly, both groups improved their walk time by ∼7% (p = 0.02, time; p = 0.61 group). Severity of pain reported following intervention did not differ between groups. Conclusion. In older adults with knee OA, a home-based NMES protocol appears to be a promising therapy for increasing QF strength in adults with knee OA without exacerbating painful symptoms.