['The origin of juvenile osteochondritis dissecans (OCD) is unknown. Existing experimental animal models of OCD most frequently involve surgically created lesions but do not examine repetitive stress as a possible cause of OCD.', 'Repetitive stresses can cause OCD-like lesions in immature animals.', 'Controlled laboratory study.', 'Six juvenile rabbits were subjected to repetitive loading forces of approximately 160% body weight to the right hindlimb during five 45-minute sessions per week for 5 weeks. The contralateral limb was the unloaded control. After 5 weeks, rabbits were euthanized and examined with radiographs, micro-computed tomography, and gross and histopathologic analysis.', 'All 6 rabbits developed osteochondral lesions in loaded limbs on the medial and lateral femoral condyles, while contralateral unloaded limbs did not demonstrate lesions. Loaded limbs developed relative osteopenia in the femoral epiphysis and tibial metaphysis with associated decreased trabecular density. Loaded limbs also demonstrated increased femoral subchondral bone thickness near the lesions. Lesions did not have grossly apparent extensive articular cartilage damage; however, cartilage thickness increased on histology with reduced ossification. Loaded knees demonstrated abundant chondrocyte cloning, limited cartilage fissuring, and a focal loss of cellularity at the articular surface.'] Do repetitive Stresses Generate Osteochondral Lesions in Skeletally Immature Rabbits?