Osteochondral defects(OCD) are very localised areas of joint damage. These conditions usually occur on the talus (ankle bone) and are a region where the cartilage and underlying bone have been disrupted. How disrupted can vary from 'bruising' to a crater or deep defect on the surface of the joint, lacking the underlying bone as well as cartilage. These most often, though not exclusively, occur after some injury to the joint.
A not uncommon history is that of a sprained ankle, which has failed to settle and gives symptoms (pain/instability) long after it should (see ‘Ankle sprain' section for a more comprehensive review of this problem).
The changes in the joint surface are very localized (often widespread in arthritis), are almost always just on the talar side of the joint (usually on both sides of the joint in arthritis) and result in softening of the joint surface (usually significant hardening in arthritis).
Generally pain is the main symptom, on weight bearing and frequently when resting as well. It is not uncommon to also have feelings of instability from the joint or locking within the joint.
Although this of injury may be shown up on a x-ray, it is easier to diagnose & define its extent using a MRI or CT scan.
It is unclear if an OCD will necessarily progress to osteoarthritis or what its natural history is. A decision to have treatment can be made on the basis of whether the patient has persisting and troublesome symptoms or not.
An ankle arthroscopy (key hole surgery) may be carried out to examine the joint and remove any loose bone fragments or cartilage. Various other surgical options like cartilage transplantation, cell culture and implantation can be considered depending upon the severity of lesions.