Quantifying Neuromuscular Electrical Stimulation Dosage after Knee Arthroplasty

Recovering functional ability after total knee arthroplasty (TKA) requires recovery of strength and voluntary activation. Short-term recovery of strength and activation are enhanced following a protocol combining strength training with neuromuscular electrical stimulation (NMES). The purpose of the study was to determine if a dose response curve could be constructed for patients who received NMES as part of their treatment after TKA. NMES dosage was quantified as the electrically evoked knee extensor torque, expressed as a percentage of the subject's maximal voluntary contraction. Dose-response curves were generated, with the associations between NMES training intensity and quadriceps strength, voluntary activation, and lean muscle cross-sectional area examined using Pearson Product-Moment Correlation Coefficients. Significantly, linear correlations were observed between NMES training intensity and both quadriceps strength and voluntary activation, but not lean muscle cross-sectional area. These results suggest that maximizing the elicited training force during rehabilitation will enhance short-term recovery following TKA.