Influence of femoral broach shape on stem alignment using anterior approach for total hip arthroplasty: A radiologic comparative study of 3 different stems

BACKGROUND: Malalignment of the femoral stem in total hip arthroplasty (THA) can detrimentally affect outcome. Poor preparation of the femur intraoperatively is an important cause of stem malalignment. PURPOSES: The objective was to compare coronal alignment of three different stems using three different broaches. METHODS: Retrospective study of three groups of 60 patients following primary THA via direct anterior approach, by the same surgeon, between January 2015 and January 2016. Each group had a similar designed stem (Corail Depuy, Targos Lepine or Meije Tornier). Groups were matched for age, body mass index, gender, side, neck shaft angle and indications. The significant difference between groups was the broach shape. Broaches for the Corail and Meije stems had a prominent shoulder laterally, while the broach of the Targos stem had a rounded less prominent shape laterally. Coronal alignment was determined radiologically at 2 months. RESULTS: The mean varus was significantly lower for the Targos stems (1.1° +/-0.8) compared to the Corail (2.3° +/-1.5) and Meije stems (1.9° +/-1.2) (p<0.0001). There were significantly less Targos stems with varus greater than 3° (1.7%, n = 1) compared to the Corail (40%, n = 24) and Meije stems (20%, n = 12) (p<0.001). CONCLUSION: A femoral broach with a prominent lateral shoulder when performing a THA via direct anterior approach will increase the risk of varus femoral stem alignment compared to a less laterally prominent broach.