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.