Familial osteochondritis dissecans

Familial osteochondritis dissecans (FOCD) is a rare inherited form of osteochondritis dissecans, a condition in which a segment of articular cartilage and the underlying subchondral bone separates from the joint surface. Unlike the more common sporadic form, familial osteochondritis dissecans occurs in multiple members of the same family and tends to affect multiple joints simultaneously (polyarticular involvement). The condition primarily affects the musculoskeletal system, with the knee being the most commonly involved joint, though the elbow, ankle, and other joints may also be affected. Patients typically present with joint pain, swelling, stiffness, and reduced range of motion. In more advanced cases, fragments of cartilage and bone may become loose within the joint space, causing locking or catching sensations during movement. The familial form often presents earlier than sporadic osteochondritis dissecans, frequently manifesting during childhood or adolescence. It may be associated with short stature in some families. The condition has been linked to mutations in the ACAN gene (encoding aggrecan, a major cartilage proteoglycan) in some families, as well as other genetic loci, suggesting genetic heterogeneity. The bilateral and polyarticular pattern of joint involvement is a distinguishing feature from the sporadic form. Treatment depends on the severity of the lesion, the patient's age, and the stability of the affected cartilage-bone fragment. Conservative management includes activity modification, rest, physical therapy, and anti-inflammatory medications, particularly in younger patients with stable lesions where there is potential for spontaneous healing. Surgical intervention, including arthroscopic drilling, fixation of loose fragments, or removal of loose bodies, may be necessary for unstable lesions or cases that fail conservative treatment. Long-term follow-up is important, as affected individuals are at increased risk for early-onset osteoarthritis in the involved joints.

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