Ipsilateral varus knee alignment correlates with increased femoral stem anteversion in primary total hip arthroplasty.

Abstract

The purpose of this study was to evaluate whether the ipsilateral knee alignment secondary to knee osteoarthritis affect positioning of the femoral component anteversion during total hip arthroplasty. Preoperative and postoperative computed tomography-based 3-D femoral models were reconstructed for 20 total hip arthroplasty patients. Prosthetic femoral stem and native femoral anteversion was measured and compared. An average increase by 4.5° ± 8.1° in femoral anteversion was found following total hip arthroplasty (p = 0.02). Strong positive correlation was found between the knee varus angle and the changes in femoral anteversion (R = 0.87, p<0.0001). The knee alignment was an independent factor for predicting the intraoperative positioning of femoral stem anteversion. The ipsilateral knee varus deformity should be considered to optimise the femoral component position during contemporary total hip arthroplasty.