Possible diagnosis for swelling of left knee, no warmth or redness, inability to walk, flex past 25 degrees. Pain medial side, left patella creaking sound with little movement. Next day bil hips, knees and ankles painful. Swelling decreased second day. Had Perthes when 4 years old, now is 17 year old male. Bil hammertoe and dorsiflexion is not to neutral.