Can Residual Leg Shortening Be Predicted in Patients With Legg-Calv,-Perthes' Disease?

Abstract

Although Legg-Calv,-Perthes' disease (LCPD) is frequently associated with varying degrees of femoral head deformity and leg length discrepancy (LLD), no factors that predict residual shortening have been clearly identified. We attempted to determine whether (1) the extent of femoral head involvement; (2) varus osteotomy; and (3) patient demographic characteristics are associated with LLD at skeletal maturity in patients with LCPD. We retrospectively reviewed the records of 168 skeletally mature patients with unilateral LCPD. The mean age at diagnosis was 7 years (range, 2-14 years). The extent of femoral head involvement was determined from the initial radiographs using the Herring lateral pillar and Catterall classifications. LLD was defined as shortening by a parts per thousand yen 1.0 cm as measured from scanograms. The patient's sex and the treatment modalities used were also recorded. LLD ranging from 10 to 38 mm (mean, 19 mm) occurred in 93 (55%) patients and was associated with the extent of femoral head involvement. Varus osteotomy was not associated with residual shortening. The patient's age at diagnosis did not affect the LLD at skeletal maturity. The strongest predictor of LLD was a lateral pillar classification of B/C or C (odds ratio, 3.5; 95% confidence interval, 1.39-8.79). The extent of femoral head involvement, but not the patient's age at diagnosis or sex or the treatment modality, can predict the LLD at skeletal maturity in patients with unilateral LCPD. Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.