ADAPTATIONS DURING THE STANCE PHASE OF GAIT FOR SIMULATED FLEXION CONTRACTURES AT THE KNEE

Adaptations in the stance phase of gait to knee flexion contractures s imulated by a knee-ankle-foot orthosis were studied in 20 healthy wome n (mean age: 25 +/- 3.6 years). Stride characteristics, joint postures , floor reactions, and indwelling electromyographic activity of the lo wer gluteus maximus, vastus lateralis, long head of the biceps femoris , and soleus muscles were measured during walking with the orthosis, w ith and without contracture simulation. Simulated knee flexion contrac ture resulted in decreased stride length and velocity and increased fo refoot weight bearing and flexion posture in stance. Increases were al so seen in magnitude and/or duration of flexion floor reaction torques and gluteus maximus, vastus lateralis, and soleus muscle activity. Th e addition of a restriction of plantar flexion resulted in a further d ecrease in velocity and stride length and a small increase in hip exte nsion posture. These results show that knee flexion contractures, simu lated in healthy subjects, cause a decrease in gait function with a si multaneous increase in muscular demand.