Legg-Calve´-Perthes disease - diagnostic value of acetabular-femoral head match index.

Early treatment of Legg-Calve´-Perthes disease (LCPD)can improve hip joint activity and life management in adulthood. However, the current classification of LCPD is based on imaging findings in the fragmented stage of the disease, which is prone to delay treatment. Therefore the aim of this study is to evaluate the potential risk factors associated with poor radiological outcomes of LCPD, and to develop a new index for hip consistency evaluation, which can be used to speculate radiographic outcomes at the time of the first visit. The acetabular-femoral head match index (AFMI) of each enrolled subject was measured in standard anterior-posterior radiograph images. In the study of patients presenting during necrosis and fragmentation stage, a significant correlation was established between AFMI and modified Stulberg classification (P<0.05). The results of binary logistic regression analyses showed that Herring classification of fragmentation stage and AFMI were the main risk factors for flat hips. Thus, we provide evidence suggesting that AFMI has a potential role in predicting patients who do not respond well to conservative treatment. Although prospective multicenter studies are needed, these results provide useful clinical clues for the early treatment of LCPD.