Kinematic and kinetic analysis of the walking pattern in hemiplegic patients with foot-drop using a peroneal nerve stimulator

OBJECTIVE: To analyze the walking pattern in hemiplegic patients using a peroneal nerve stimulator to locate possible harmful mechanical effects on the musculo-skeletal system. DESIGN: Eight hemiplegic patients participated in the study. All patients had used a peroneal nerve stimulator regularly for more than two years and were able to perform unassisted walking. BACKGROUND: Peroneal nerve stimulators are widely applied for correction of foot-drop in hemiplegic patients. The stimulators do not induce normal dorsi-flexion, but a rather exaggerated dorsi-flexion and eventually eversion which might be harmful. METHODS: Three-dimensional kinematic and kinetic analyses of the walking patterns at self-selected speeds were performed with the patients walking without the stimulator and with the stimulator turned on. RESULTS: The walking speed increased on average from 0.77 (S.D., 0.83) to 0.84 (S.D., 0.11) (7.6%, P=0. 005) when the stimulator was used, however no uniform changes in the walking pattern and joint loads were observed. The total work (generation+absorption) produced by the affected leg (both with and without the peroneal nerve stimulator) was significantly lower (P=0. 005) than that of the contralateral leg. Deviations from normal power profiles were observed both on the affected and the contralateral side, and the walking efficiency was 57% lower compared to normal subjects. The estimated peak bone-on-bone forces corresponded to about 50% of what previously has been observed during normal walking at self-selected speed. CONCLUSIONS: The use of the peroneal nerve stimulator do not introduce any excessive and potential harmful mechanical loads. RELEVANCE: Applied correctly, the peroneal nerve stimulator can be used as an aid for foot-drop correction in hemiplegic patients without causing excessive wear on the joints in the lower extremity.