Bilateral Legg-Calvé-Perthes disease appears to run a more severe course compared to unilateral disease, with high rates of severe radiographic classifications at skeletal maturity.
Twenty-five patients or 50 hips with bilateral Legg-Calvé-Perthes disease were reviewed at skeletal maturity in the orthopaedic departments of Leuven, Belgium, and Montpellier, France. The two groups were very similar as to age at onset of the disease, severity of involvement, and classification at skeletal maturity. The results seem to indicate that bilateral disease runs a more severe course as compared with unilateral Legg-Calvé-Perthes disease. Eighty percent presented with a Catterall group III and IV and Herring classification B and C. Forty-eight percent rated as Stulberg 4 and 5 at skeletal maturity.
Bogaert et al. (1999) studied this question.