Late metachronous involvement of the contralateral hip in Legg-Calvé-Perthes disease.

Bilateral hip involvement in Legg-Calvé-Perthes disease occurs in approximately 10-13% of cases. Although both synchronous and metachronous involvement of the two hips have been described, metachronous involvement is rare and generally occurs within 6 months to 4 years of initial diagnosis. We report the cases of two patients diagnosed with late metachronous involvement of the contralateral hip 8.5 and 9.8 years after initial presentation. This is later than previously reported metachronous involvement in Legg-Calvé-Perthes disease and emphasizes that patients with Legg-Calvé-Perthes disease may be at prolonged risk for recurrent disease.