in most cases although resolution can be expected to take between 12 and 18 months Resistant cases respond well to aspiration of synovial fluid and injection of corticosteroids Surgery is rarely necessary in children OSTEOCHONDRITIS DISSECANS Current Evidence Osteochondritis dissecans is an acquired lesion involving osteonecrosis of subchondral bone Adults are often diagnosed with osteochondritis dissecans; however, it remains primarily a condition of the adolescent age group, with the highest incidence occurring among male athletes between 12 and 16 years of age The term “juvenile osteochondritis dissecans” (JOCD) refers to lesions that occur prior to the closure of the growth plates, whereas “adult osteochondritis dissecans” presents after the closure of the growth plate This distinction has important implications for prognosis and treatment because the likelihood of spontaneous healing is significantly greater in JOCD The primary sites of osteochondritis dissecans include the medial femoral condyle in the knee, the posteromedial aspect of the talus in the ankle, and the capitellum in the elbow It is less frequently reported in the hip, foot, and wrist Involvement of multiple sites is rare, although some series report bilateral knee lesions in up to 25% of cases The underlying cause of osteochondritis dissecans remains controversial and may differ based on the anatomic location of the lesion Trauma, vascular insult, genetic predisposition, and abnormalities of ossification have all been proposed as possible etiologies The greatest evidence supports repetitive trauma as the sole or major contributing cause of the pathology Overuse injury is most clearly associated with osteochondritis dissecans of the capitellum, where the majority of cases occur in Little League pitchers Higher incidences of osteochondritis dissecans of the knee and ankle are seen in participants of activities that place increased stress on these areas, such as distance running, ballet, and basketball Focal necrosis is suspected to follow the initial insult Spontaneous resolution may occur at this point, or the lesion may progress with the subchondral bone undergoing various degrees of separation from the underlying epiphysis In advanced stages, complete separation of the osteochondral fragment results in a free-floating body within the joint, which can disrupt normal mechanical function Histologic studies have not demonstrated any evidence of inflammation When the disease occurs in the second decade of life, long-term outcome is generally good Progression to osteoarthritis or other degenerative joint diseases