The purpose of this study was to determine the relative contributions made by pathoanatomical factors responsible for femoral shortening in Legg-Calve-Perthes disease (LCPD), and to devise a method of reducing the amount of residual shortening based on a better understanding of its pathoanatomy and developmental pattern in LCPD.

We measured shortening of three anatomical components, namely, the femoral epiphysis, neck, and diaphysis on the teleoroentgenograms of 106 LCPD patients, comprised of 35 children with active disease, 24 in the healing stage, and 47 at skeletal maturity.

The proportional contributions made by these 3 anatomical components to residual shortening at skeletal maturity were; 20% by the epiphysis (epiphyseal flattening), 53% by the neck (physeal growth retardation), and 27% by the diaphysis (underuse atrophy). These contributions differed according to disease stage and shortening severity. Mean diaphyseal shortening was 3.9 mm at skeletal maturity, but this increased to 5.8 mm when only patients with severe shortening (20 mm or more) were included.

Our findings suggest that diaphyseal shortening is likely to be minimized by the implementation of limb exercise programs.