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Osteochondritis dissecans (OCD) is a condition where a segment of subchondral bone and its overlying cartilage becomes ischemic, potentially leading to fragmentation and separation, forming an intra-articular loose body.

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It most commonly affects children and adolescents but can also occur in adults.

https://www.youtube.com/watch?v=qdMzgniskh8

Etiopathogenesis

Thought to result from repetitive microtrauma, vascular insufficiency, or genetic predisposition.
Juvenile OCD: Open growth plates, better prognosis.
Adult OCD: Closed growth plates, higher risk of loose bodies and surgery.

![Schematic of a distal femur undergoing ossification in the epiphysis from left to right with an injury to the articular-epiphyseal cartilage complex that ultimately becomes an osteochondritis dissecans lesion as the surrounding and unaffected ossification front continues growth.

Edmonds EW, Tompkins M, Bomar JD, Pennock AT. Evaluating the etiology of osteochondritis dissecans of the knee: The role of the Articular-Epiphyseal Cartilage Complex. Journal of the Pediatric Orthopaedic Society of North America. 2023;5(4):677. doi:10.55275/jposna-2023-677](attachment:b431f238-35cd-411b-a44b-b9ba201386d2:gr2_lrg.jpg)

Schematic of a distal femur undergoing ossification in the epiphysis from left to right with an injury to the articular-epiphyseal cartilage complex that ultimately becomes an osteochondritis dissecans lesion as the surrounding and unaffected ossification front continues growth.

Clinical Presentation

Pain with activity.
Joint swelling and mechanical symptoms (locking, catching).
Decreased range of motion.
In chronic/unstable cases: joint effusion, instability.

Common Sites

Bone	Region
Knee (most common)	• Medial femoral condyle (posterolateral aspect).
• Lateral femoral condyle.
Ankle	• Talar dome (especially lateral and medial aspects).
Elbow	• Capitellum (common in throwing athletes and gymnasts).
Hip, shoulder, and other joints	Less common

Radiology

https://doi.org/10.2214/AJR.24.31724