Brief Outline of Osteochondritis Dissecans
Osteochondritis dissecans (loose bodies in the joint) occurs when a fragment of bone adjacent to the articular surface of a joint is deprived of its blood supply, leading to avascular necrosis. This cause the cartilage to become brittle and a piece, or pieces, may break off. If the cartilage gets into the joint, it can cause pain and inflammation. The space in the ankle joint is very small and when a bone or cartilage fragment from the talus bone gets lodged in the joint, it can cause pain, swelling, and loss of movement in the ankle. These symptoms may come and go as the free-floating fragment floats in and out of the joint. Prior ankle injuries make a person susceptible to this condition, as does any blockage of blood flow to the feet.
Anatomy and Physiology for Osteochondritis Dissecans
The tarsals are the seven bones of the ankle. The two largest tarsals carry the body weight: the calcaneus, or the heel bone, and the talus, which lies between the tibia and the calcaneus. The tibia and fibula rest on top of the talus. The articular surface of the talus is covered with cartilage to cushion and protect it. There is very little blood flow to this area so repairing damage is difficult for the body. This can result in the tissue becoming brittle and breaking off. A fracture can occur on the surface of the talus, or the cartilage may become bruised from any twisting injury causing the talus to come in hard contact with the tibia and fibula.
Cause of Osteochondritis Dissecans
Loss of blood flow to the articular surface of the talus along with injury to the bone. Repetitive wear on the cartilage and bone surface of the talus. Previous ankle injury.
Signs and Symptoms of Osteochondritis Dissecans
Pain and discomfort in the joint. If the fragment becomes detached and lodged in the joint, swelling and loss of movement may occur. A catching sensation in the ankle may be felt.
Complications If Left Osteochondritis Dissecans Unattended
The loose bodies in the joint can cause scarring and additional damage if left unattended. As the joint moves and the loose body grinds against the other cartilage and bone surfaced, it will wear at these surfaces making them rough and eventually lead to arthritis.