Risk factors associated with greater trochanteric overgrowth secondary to Legg-Calvé-Perthes disease: a retrospective observational study

Legg-Calve’-Perthes disease (LCPD) is a common osteoarthrosis in children. Studies on LCPD are mainly focused on how to maintain the sphericity of the femoral head and improve the congruency of the hip, yet there has not been enough attention given to secondary deformities such as greater trochanteric overgrowth (GTO). Therefore, we conducted a retrospective study to determine the risk factors associated with GTO secondary to LCPD. The demographic and imaging data of children with LCPD from 2008 to 2021 were retrospectively analyzed. The age at diagnosis, sex, lateral type, treatment methods, Herring lateral pillar classification, Catterall classification, the signs of hip“at risk” and Stulberg classification were recorded. The articulotrochanteric distance (ATD) value of hip < + 5 mm was diagnosed as GTO. Spearman rank correlation test and logistic regression analysis were used to evaluate possible correlations and the risk factors for GTO secondary to LCPD. 125 children with LCPD were enrolled, 91 patients without GTO and 34 patients with GTO, the positive rate of GTO was 27.2%. Spearman rank correlation test showed that GTO was correlated with Herring lateral pillar classification(ρ = 0.276, p = 0.002), the sign of hip “at risk” (ρ = 0.305,p<0.001) and Stulberg classification ( ρ = 0.346, p<0.001). Multivariate logistic regression analysis suggested that the risk of GTO was 2.7 times for LCPD with the sign of hip “at risk” than without the sign of hip “at risk” (OR:2.672,95%CI:1.030–6.930), 2.9 times (OR:2.941, 95%CI:1.181–7.324) after combined sub-classifications of similar properties. The risk of GTO was 3.9 times for LCPD with Stulberg III/IV/V than with Stulberg I/II (OR:3.899, 95%CI:1.481–10.262). Hip ‘at-risk’ signs are independent risk factors with early predictive value for GTO secondary to LCPD. The Stulberg classification is positively correlated with GTO at skeletal maturity.