What is an osteochondral lesion?

Definition of Osteochondral Lesion

An osteochondral lesion is damage to both the articular cartilage surface and the underlying subchondral bone of a joint, distinguishing it from purely chondral injuries that affect only the cartilage layer. 1

Key Anatomical Components

• The lesion involves two distinct tissue layers: the articular cartilage (the smooth surface covering the joint) and the subchondral bone (the bone layer immediately beneath the cartilage). 1

• This dual-layer involvement is what differentiates osteochondral lesions from isolated cartilage damage, making them more complex injuries that affect both the joint surface and its structural foundation. 1

Terminology and Classification

• Multiple terms describe this condition including osteochondritis dissecans (OCD), osteochondral fracture, and osteochondral defect—all referring to the same basic pathology of combined cartilage and bone injury. 2

• The American Academy of Orthopaedic Surgeons classifies these defects using the Outerbridge system (Grades 0-4), where Grade 4 represents complete cartilage loss with exposed subchondral bone. 1

Etiology and Clinical Significance

• Up to 75% of osteochondral lesions result from trauma such as ankle sprains or fractures, though repetitive microtrauma with vascular impairment also contributes to their development. 3, 4

• These lesions have limited healing capacity and can progress from asymptomatic to causing deep joint pain, subchondral bone cysts, and potentially disabling arthritis if left untreated. 1, 5

• The condition seriously affects patients' quality of life and work capacity, potentially leading to disability and premature osteoarthritis of the affected joint. 5, 6

Diagnostic Considerations

• MRI without contrast is the reference standard for detecting osteochondral lesions, with 96% sensitivity for identifying the abnormality and 97% sensitivity for determining lesion stability. 1

• Plain radiographs detect only 59% of osteochondral lesions, missing many cartilage-only injuries, which is why MRI should be obtained within 2-3 weeks when an osteochondral injury is suspected. 1

• CT arthrography is helpful for evaluating osteochondral lesion stability when MRI is contraindicated, though it has lower sensitivity than MRI despite 99% specificity. 7, 1

Clinical Pitfall

• These lesions are often unrecognized acutely and may be misdiagnosed as simple joint arthritis, leading to years of untreated progressive damage—early recognition through appropriate imaging is critical to prevent long-term disability. 3, 6