Response of male and female subjects after total knee arthroplasty to repeated neuromuscular electrical stimulation of the quadriceps femoris muscle

Laufer Y, Snyder-Mackler L: Response of male and female subjects after total knee arthroplasty to repeated neuromuscular electrical stimulation of the quadriceps femoris muscle. OBJECTIVES:: To examine responses to repeated neuromuscular electrical stimulation of the quadriceps femoris muscle in male and female subjects after total knee arthroplasty. DESIGN:: Sixty-four subjects who underwent total knee arthroplasty were treated with neuromuscular electrical stimulation two to three times a week for 6 wks in addition to an exercise program. Measures of the quadriceps femoris muscle's maximal voluntary isometric contraction (MVIC), maximal electrically induced contractions, and current intensity, in response to ten electrically induced contractions per session over 15 treatment sessions, were monitored with an isokinetic dynamometer. RESULTS:: Mean (SD) of maximal electrically induced contractions expressed as percentage of MVIC (%MVIC) was 44.5% (18.2%). Forces of MVIC and maximal electrically induced contractions were significantly stronger in the male subjects. However, there were no gender differences in %MVIC. All force measures increased significantly across time. Male subjects tolerated higher current intensities, with both sexes showing a similar pattern of habituation to current intensity. CONCLUSIONS:: After total knee arthroplasty, most elderly subjects can tolerate neuromuscular electrical stimulation at current intensities sufficient to elicit quadriceps femoris muscle contractions within the therapeutic range recommended for muscle strengthening. Although male subjects can tolerate stronger current intensities, similar %MVIC is activated in female and male subjects with impaired muscle function, indicating a similar potential for treatment effectiveness.