Idiopathic avascular necrosis

Cartilage is the tough but flexible tissue that covers the ends of your bones at a joint. It also gives shape and support to other parts of your body, such as your ears, nose and windpipe. Healthy cartilage helps you move by allowing your bones to glide over each other. It also protects bones by preventing them from rubbing against each other. Injured, inflamed, or damaged cartilage can cause symptoms such as pain and limited movement. It can also lead to joint damage and deformity. Causes of cartilage problems include Tears and injuries, such as sports injuries Genetic factors Other disorders, such as some types of arthritisOsteoarthritis results from breakdown of cartilage.NIH: National Institute of Arthritis and Musculoskeletal and Skin Diseases