Osteochondritis dissecans (OD) is a focal aseptic necrosis of subchondral bone in which a bone-cartilage fragment detaches and becomes displaced in the joint space. School-aged children and adolescents are most commonly affected. OD occurs as a result of overuse or trauma, and 75% of cases affect the knee. Symptoms include pain and joint locking or catching. X-ray is the best initial test for suspected OD, but MRI is better able to detect early disease. First-line treatment includes reducing physical activity. Surgery is indicated if the bone-cartilage fragment is completely displaced and includes arthroscopic extraction, open fixation, and transplantation procedures.
Epidemiological data refers to the US, unless otherwise specified.
The etiology is unknown. Proposed theories include mechanical stress and repetitive trauma.
- Most frequently affected joint: knee
- In early lesions, nonlocalized pain during physical activity in school-aged children or adolescents
- Gradual stiffness with joint locking or catching
- Antalgic gait with lateral rotation of the ipsilateral foot
- Pain on palpation of the femoral condyles when the knee is in flexion
- Full range of motion is retained
OD may be difficult to differentiate from osteonecrosis, but young patients are much more likely to have OD.
- Initial test
- May be normal in early stages
- More advanced lesions appear as a subchondral bony fragment surrounded by radiolucency.
Osteochondritis dissecans is a radiographic diagnosis.
- Conservative therapy: first-line treatment
- Children with completely detached and displaced intra-articular fragments
- Children who have not responded to 4–6 months of conservative therapy
- Most adult patients with OD, although conservative therapy can be attempted for small or stable lesions
- Arthroscopic extraction of the intra-articular loose fragment
- Other options depend on the stage and size of lesion, as well as skeletal maturity.
- Most patients, especially children without a loose body, heal completely without complications.
- Chronic pain
- Mechanical symptoms
We list the most important complications. The selection is not exhaustive.