Prognosis and prognostic factors of Legg-Calve-Perthes disease.

This is an overall review of the published literature in the past 100 years on the prognosis and prognostic factors of Legg-Calve-Perthes disease (LCPD). There were considerable limitations and inadequacies of the reported series. LCPD is not a common disease, and thus most reports were based on relatively small series collected retrospectively over a long period of time without clearly defined case selection, assessment, treatment, follow-up period, and outcome measures. Few studies, if any, would satisfy the strict definition of prognosis, which should only mean those prognostic factors derived from observation of the natural history of the disease-that is the uninterrupted progressive development of a disease that runs its course from onset-inception to resolution without any intervention or treatment. This review attempted to summarize from the mixed series of studies the generally described demographic, clinical, and radiologic prognostic factors of LCPD. The most important radiologic prognostic signs include the extent of femoral capital epiphysis involvement, the degree of metaphyseal changes, and lateral subluxation of femoral head and depend significantly on the time of assessment after the onset of the disease. More detailed discussions on prognostication based on the structured classification systems that have evolved in the past few decades would be described.