[Electromyographic studies on the musculature of the knee with osteoarthritis].

Action of muscles around the knee in walking on a treadmill was studied by electromyography in young normal subjects and in patients with osteoarthritis of the knee. The followings were concluded. The quadriceps femoris stabilizes the knee joint in the sagittal plane, showing higher activity with an increase in faster walking. The tensor fasciae latae and gluteus medius muscles are important in the frontal plane stability, working primarily in the slow walk. Hamstring controls finely the knee joint under various circumstances. The muscle of those with osteoarthritis of the knee on walking slowly shows a similar pattern of activity as that of the normal fast walking. All of the muscles apparently are put into stabilizing mechanism of the joint in the stance phase leaving less reserve in their activity. A forward bending in posture results in changes of muscle activity around the knee, which can play an important role in the development of osteoarthritis of the knee.