Patients with osteoarthritis (OA) of the knee usually have a posteriorly, tilted pelvis and a bent knee with varus deformity. Such patients usually show an increase of muscle tone and pain due to pressure in the tensor fasciae latae muscle (TFL) and biceps femoris muscle (BFS) and further more, insufficient vastus medial muscle (VM). We perform therapy to stretch TFL and BFS in the supine and sitting positions and contract VM. We can't obtain enough effect of therapy because it gives rise to disorders again like the above in the closed kinetic chain (CKC) exercise while standing and walking, although these disorders improve in open kinetic chain (OKC) exercise. Thus, we perform posture control while standing or sitting to improve the pelvis tilt to add to the direct therapy of each muscle in OKC. In performing this therapy, we observed that such disorders were improved in CKC. Therefore, we experimented with electromyography (EMG) on healthy subjects to define the effects on TFL, BFS and VM of changing the angle of the pelvis tilted posteriorly together with varus deformity of the knee. TFL is involved in keeping the knee bent in middle position of pelvis, and keeping the knee bent and varus deformity of the knee in hip extension and internal rotation in posterior tilt of the pelvis. BF and BFL are involved in keeping the knee and hip bent in middle position of pelvis. When the pelvis is tilted posteriorly, BFL is involved in keeping the knee bent, BF (BFS) is involved in braking varus deformity of the knee as well as keeping the knee bent. VM is involved in keeping the knee bent in middle position of pelvis and when the pelvis is tilted posteriorly. VM is not involved in controlling varus deformity of the knee. From these result, we suggest that it's important when performing the therapy of posture control to consider the posture of the pelvis besides assessment and therapy of the knee for patients with OA of the knee showing increase of muscle tone and pain due to pressure of TFL and BFS.
