Muscle strength. Muscles are the major supporting structures for joints and are critical for joint movement and stability.26 Studies have shown that quadriceps weakness commonly accompanies knee OA.27This finding was attributed to disuse atrophy secondary to knee pain and abnormal biomechanics, but extensor weakness is also present with asymptomatic tibiofemoral OA, suggesting that quadriceps weakness is a risk factor for knee OA development. Individuals who developed knee OA during follow-up had 18% less quadriceps strength at baseline than those who did not. The influences of muscle strength and afferent sensory dysfunction on the progression of knee OA are uncertain.27