Factors that Affect Version of the J-Taper Stem

Background: The appropriate combination of acetabular component and stem anteversion is needed to reduce implant impingement and dislocation of total hip arthroplasty (THA). J-Taper is a tapered wedge stem with a relatively shorter small area of arc spray coating compared with conventionally tapered wedge stems. We examined the factors that affect postoperative version of J-Taper. Methods: A total of 59 patients who underwent primary THA were assessed by computed tomography. Preoperative femoral neck and postoperative stem anteversion, stem sagittal alignment, and stem coronal alignment were measured. Results: Mean femoral neck anteversion was 26.1° ± 12.2°. Mean stem version was 32.3° ± 9.0°. Multiple linear regression analysis showed that femoral neck anteversion (p<0.01), stem sagittal alignment (p=0.045), and body height (p=0.048) were positively correlated with stem aversion. The stem version was significantly increased compared with that of native femoral anteversion (6.3° ± 10.9°). Multiple linear regression analysis showed that femoral neck anteversion was negatively correlated with an increased angle of stem version, body height, and stem sagittal alignment was positively correlated. Conclusions: Our findings are helpful for surgeons during preoperative planning to achieve the appropriate combined anteversion.