Osteochondritis Dissecans of the Knee
DNB Orthopaedics • May 2024 • Paper II • 10 Marks
Introduction
Osteochondritis dissecans (OCD) is an acquired focal disorder of the subchondral bone in which a localized segment of subchondral bone, with its overlying articular cartilage, may become unstable and potentially separate from the surrounding bone.
The knee is the commonest site. The classic lesion occurs on the lateral aspect of the medial femoral condyle, close to the intercondylar notch.
Core principle: Prognosis is determined mainly by skeletal maturity and stability of the lesion.
Important Classification
Juvenile OCD
Occurs with an open physis. Healing potential is comparatively high.
Adult OCD
Occurs after physeal closure. Lower potential for spontaneous healing and higher likelihood of instability.
Etiopathogenesis
The exact cause is multifactorial and not completely established. Proposed factors include:
- Repetitive microtrauma
- Subchondral stress injury
- Local vascular factors
- Abnormal ossification
- Genetic/familial predisposition in selected cases
- Mechanical malalignment
Despite the historical name “osteochondritis,” the disorder is not primarily an inflammatory disease.
Common Sites in the Knee
- Medial femoral condyle — commonest
- Lateral femoral condyle
- Trochlea — less common
- Patella — uncommon
The classic lesion is on the posterolateral / intercondylar surface of the medial femoral…