An intraarticular hip process with chondrolysis simulating Perthes disease: a report of five cases.

Radiographic findings in Legg-Calvé-Perthes disease (LCPD) are well known. Four classic stages have been described: incipient stage, avascular stage, fragmentation stage, and residual stage. Final femoral morphology is normally coxa magna, which is associated frequently with hypertrophy of the articular cartilage. We describe five patients with a hip process that initially presented clinical and radiographic findings compatible with LCPD. However, none of these patients showed the typical sequence of the radiographic stages. Instead, the early signs were the formation of rounded areas of rarefaction in the epiphysis and/or the metaphysis with considerable surrounding osteoporosis, early narrowing of the articular space, and final coxa breva morphology with signs of osteoarthritis. No condensation or fragmentation stages were observed. The pathologic study showed complete atrophy of the synovial villi with hyaline cartilage and bone necrosis. The patients described herein presented an intraarticular hip process, initially with signs and symptoms similar to LCPD but with an ultimate clinical evolution that differs from ordinary LCPD.