KNEE PAIN WHILE WALKING ON STAIRS AND CROSS LEG SITTING???? Chondromalacia patella is the breakdown of cartilage on the underside of the kneecap (patella). When the kneecap rubs against the thigh bone, it hurts and swells. It is common among runners and other athletes and has been given the nickname “runner's knee. For any Knee related issues Consult DR DEEPAK KOLI Orthopaedic and Joint Replacement Surgeon Punawale/ Rawet/ Tathwade/ Kiwale 9922120200/7769088519