Myositis ossificans is the formation of bone in an area bruised by injury. This usually occurs in the arm or thigh. Myositis ossificans develops in 10% to 20% of thigh contusions. Myositis means inflammation of muscle, and ossificans means bone. A contusion to the arm or thigh causes bleeding, and a clot of blood (hematoma) forms, usually within the muscle. This hematoma then may become bone.
Pain, tenderness, swelling, and warmth of the injured extremity Feeling of fullness deep in the injured extremity Discoloration and bruising of the skin Restricted activity (stiffness of the joints) of the injured extremity, including loss of motion of the knee (thigh) or elbow (arm), depending on the area injured
The cause of myositis ossificans is unknown. It most commonly develops within a muscle that has sustained a severe contusion (bruise), usually from direct contact. The muscle is usually crushed between the underlying bone and an object (another player’s helmet, a knee or elbow, or a ball).
Initial treatment consists of ice, and bandages to relieve the pain and swelling. Further, stretching of the affected joint, maintaining strength or muscle control of the injured extremity, and modifying activity help restore function to the extremity. These may help reduce the incidence of myositis ossificans. These all can be carried out at home, although referral to a physical therapist or athletic trainer for further evaluation and treatment may be helpful. Crutches for thigh contusions may be recommended. A neoprene (wetsuit material) or other bandage may help reduce some of the symptoms. Nonsteroidal anti-inflammatory medications may also reduce the formation of bone of the hematoma (clot). Most athletes with this problem can function well. Surgery to remove the bone of myositis ossificans is considered only if symptoms (pain) persist, loss of joint motion persists, or the bone is unusually large; it is done only after the bone is fully mature (at least 6 to 12 months after the injury).