OBJECTIVETo observe the distribution law and study the factors related to the femoral neck anteversion angle among the patients with developmental dysplasia of the hip of Hartofilakidis type I.

METHODSAmong the patients with hip dysplasia of Hartofilakidis type I who was admitted to Department of Orthopaedic Surgery, the First Affiliated Hospital of People's Liberation Army General Hospital from June 2010 to June 2013, a total of 340 hips (25 male and 161 female) were included in the study. The average age was 28.3 years, ranging from 13.5 to 49.9 years. The observation index included: femoral neck anteversion angle, lateral center-edge angle, acetabular index angle, lateral displacement of the femoral head, superior displacement of the femoral head, continuity of Shenton's line and Calve's line. The correlation between different factors was analyzed, and the factor closest to femoral neck anteversion angle was analyzed further by regression analysis.

RESULTSAmong the patients of developmental dysplasia of the hip of Hartofilakidis type I, the femoral neck anteversion angle increased, with an average of 28°±13°. Correlation and regression analysis showed significant negative correlation with treatment age (r=-0.158, P=0.003; t=-6.892, P=0.000); positive correlation with gender (r=0.332, P=0.000; t=-4.376, P=0.000); significant positive correlation with lateral displacement of the femoral head (r=0.092, P=0.000; t=3.766, P=0.000); significant negative correlation with central-edge angle (r=-0.122, P=0.024; t=2.031, P=0.043). The femoral neck anteversion angle showed correlation with acetabular index angle, continuity of Calve's line and superior displacement of the femoral head in correlation analysis, not in regression analysis, however, it did not show correlation with side and continuity of Shenton's line.

CONCLUSIONAmong the patients of developmental dysplasia of the hip of Hartofilakidis type I, the increasing of the femoral neck anteversion angle may not only lead to early onset and therefore early treatment of pain in the hip joint but also the lateral displacement of the femoral head that requires immediate medical attention.