Change of CCD angle and femoral anteversion angle by total hip replacement

Purpose: The aim of the present study was to measure and interpret the chan ge of the collodiaphyseal (CCD) angle and femoral anteversion after total h ip replacement. Methods: We prospectively examined 52 patients with coxarth rosis, who were treated by total hip replacement. Preoperatively and postop eratively we used a standard X-ray ap view to measure the CCD angle and com puterized tomography to determine the femoral anteversion. These projected angles were converted into the real angles by using the method of Konig and Schult. Results: On average the preoperative real CCD angle was 128 degree s (+/- 8,9 degrees) and the postoperative angle 145 degrees (+/-4,8 degrees ), preoperatively the real femoral anteversion angle was 14,1 degrees (+/- 6,9 degrees) and postoperatively 10,8 degrees (+/-6,2 degrees). Conclusions : The effect of the postoperative valgisation can be explained by the given CCD angle of the used femoral stem prosthesis of 140 degrees (cemented Wel ler II stem) and 145 degrees (cementless CLS classic stem). It is possible that due to the valgisation and the decreased offset of the femoral stem pr osthesis compared to the preoperative conditions the gluteal muscles are in sufficient and overloaded. It is also known that the change of the femoral anteversion from the physiological conditions causes an increase of the tor sional moment. The resulting increased interface load could possibly be a s eason for loosening of the femoral stem. The conclusion can be drawn that t he CCD angle and the femoral anteversion should more carefully be considere d by the surgeon in total hip replacement. This could be reached by an exac t implantation technique and the choice of the appropriate stem prosthesis with different CCD angles.