Osteochondral injuries often present in a non-specific way, as a painful ankle after injury. There may also be features of instability, synovitis, impingement, tendon or nerve injuries.
The main presenting symptom is pain, which may be quite diffuse or localised to the region of the lesion. There is usually a history of injury to the ankle, which may have been considered a sprain that failed to resolve. Sometimes the presentation is quite acute, with severe pain and swelling in the ankle after injury and difficulty weightbearing.
Some patients complain of locking or catching - which may be due to a loose body or to synovitis – or of instability.
Many patients have an antalgic gait. There is usually tenderness in the joint which may be localised, giving a clue to the site of the lesion, or diffuse. Lateral lesions often have tenderness in the angle between the tibia and fibula, while medial lesions may have medial talar dome tenderness in plantar flexion. Occasionally a loose body may be palpable.
There may be swelling or synovitis, and 30-50% of patients have ligament injuries. The Molloy test for impingement, and the anterior draw and talar tilt tests for instability may be positive.
Although osteochondral injury tends to be a diagnosis of suspicion which requires further investigation, we feel the patient should be assessed by a foot and ankle specialist before obtaining MRI, particularly in view of the study of Tocci et al which indicated that many MRIs were not relevant to decision making or care planning. Although there is not enough evidence to provide clear guidelines, we agree with Robinson et al (2003) that a significant ankle injury which has failed to improve by three months should be considered for further investigation. Clinically severe ankle injuries which are failing to settle may warrant MRI before this time.