Osteochondritis dissecans involving the trochlea: report of two patients (three elbows) and review of the literature.

Osteochondritis dissecans (OCD) is an idiopathic lesion of subchondral bone resulting in separation of the articular cartilage and subchondral bone. Osteochondritis of the elbow primarily involves the capitellum. Only two cases involving the trochlea have been reported, one in the English literature and one in the German literature. Osteochondritis dissecans has been confused with other joint surface abnormalities, and therefore the orthopaedic literature must be read with scrutiny. Some of these other conditions include osteochondral fractures, osteonecrosis, accessory centers of ossification, and hereditary epiphyseal dysplasia. The authors describe two patients (one bilateral) with OCD involving the trochlea of the humerus. The first is a 12-year-old boy in whom an open biopsy was performed to rule out neoplastic lesions. The second is a 14-year-old boy with bilateral OCD that was recognized secondary to the similarity to the first patient. This patient was successfully treated conservatively. The first patient illustrates how recognition of OCD in the trochlea may prevent unnecessary biopsy. Osteochondritis dissecans should be part of the differential of lesions involving the trochlea.