The influence of functional electrical stimulation on the properties of vastus lateralis fibres following total knee arthroplasty.

The influence of functional electrical muscle stimulation (FES) on selected properties of vastus lateralis muscle fibres was studied in patients recovering from total knee arthroplasty for osteoarthritis. Prior to surgery, on the average, muscle biopsies from the vastus lateralis could be characterized as having a predominance of Type I fibres which were significantly larger in cross-sectional area than the Type II fibres in the same sample. Following surgery, muscle biopsies from a group of patients (n = 7) which received continuous passive motion and no FES, exhibited a marked increase in the proportion of Type II fibres along with a general atrophy of both the Type I and Type II fibres. Patients receiving passive motion and FES (n = 9) also showed an increase in the relative percentage of Type II fibres. Post-operatively, however, there was no significant reduction in fibre area in the stimulated muscles. These data suggest that FES was effective in attenuating the muscle atrophy associated with total knee arthroplasty but had no influence on those metabolic properties which were related to muscle fibre type classification criteria.