Osteochondritis dissecans

Definition

A localised condition affecting an articular surface that involves separation of a segment of cartilage & subchondral bone.

• Bilateral in 20-30%

• posterior lateral aspect of the medial femoral condyle in 70%

• lateral femoral condyle in 20%

• patella in 10%

Guhl Arthroscopic Classification

Lesions are classified based on articular cartilage integrity (open or closed) and the stability of the underlying subchondral bone and its bed (stable or unstable). (Clanton & DeLee, CORR 1982);

A - Intact lesions

B - Lesions showing signs of early separation

C - Partially detached lesions

D - Craters with loose bodies (salvageable or unsalvageable)

Investigations

X-rays & tunnel views

MRI  - to assess the fragment's articular cartilage continuity and the size and viability of its subchondral bone. 

Natural History 

The natural history is directly dependent on age at presentation (Pappas Classification):

• In the juvenile type (patients with completely open distal femoral physis), the prognosis is excellent if the lesion is a closed, stable one. 

• In the adolescent with partial physeal closure, the prognosis is unknown because the lesion may act as either the juvenile or adult type. 

• The adult type (closed physis) has a poorer prognosis because of the limited healing potential of the lesion. 

Treatment (based on Pappas)

Skeletally Immature Patient (< 12yrs):

• Non Operative treatment is recommended, since the lesion will frequently heal  if the fragment has not detached. 

• Articular cartilage overlying these lesions should be normal & should protect the OCD defect during healing. 

• Protected crutch walking and gentle ROM, since ROM is thought to have beneficial effects on cartilage healing.