An ankle ‘chondral’ defect refers to a focal area of damage involving the joint cartilage; whereas an ankle ‘osteochondral’ defect refers to that of which involves both cartilage and bone. It can be a result of trauma to the ankle, such as a severe twisting injury, but can also be related to genetic disorders of cartilage.
An ankle osteochondral defect is considered different than arthritis in that it is usually an acute injury to an isolated area of the ankle joint; and not ‘wear and tear’ changes to the cartilage that usually involve the entire ankle joint as in arthritis. Patients typically have pain to the ankle joint with standing and walking and may even experience some painful ‘locking and clicking’ as well as instability symptoms due to a loose fragment of cartilage or bone in the joint that may catch. Diagnosis of an osteochondral defect is usually by clinical and radiographic examination, usually requiring an MRI of the ankle if the defect is not seen on x-ray.
The treatment of these defects is also different from that of arthritis as the affected patient is usually younger and more active. To prevent the defect from increasing in size and to slow the progression of arthritis, treatment is usually proactive and commonly requires surgery. An isolated loose cartilage/bone fragment is not usually repairable and should be removed, which can commonly be done through a scope, or arthroscopically. However, the exposed bone in the joint surface defect needs to be treated or ‘filled’ through a number of different surgical methods.
‘Microfracture’ is one technique to treat a small isolated cartilage defect by making tiny holes in the bone to stimulate bleeding from the underlying bone marrow. The stem cells will flow to and fill the area of the defect and develop into a different form of cartilage. Another technique, reserved for larger defects, is to transplant cartilage and bone from another part of the body or from a ‘donor’ to fill the defect and allow it to incorporate. Whichever technique is used, the ankle joint is no longer the same, losing its smooth joint surface, and will eventually progress to post-traumatic arthritis. However, early diagnosis and treatment can definitely slow this progression.