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

ABSTRACT

PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: The ipsilateral knee varus deformity should be considered to optimise the femoral component position during contemporary total hip arthroplasty.