Agreement Between Proximal Femoral Geometry and Component Design in Total Hip Arthroplasty: Implications for Implant Choice

Abstract Background The present study aimed to analyze the agreement between proximal femoral geometry of adult hips and femoral component design in total hip arthroplasty. Methods Anatomical femoral offset (FO Anat ) and the anatomical neck-shaft angle (NSA Anat ) of 800 adult hips were measured by computed tomography scans, and anatomical femoral neck height (FH Anat ) was calculated. Corresponding best-fit implants of the most common hip system (standard, high offset and varus variant) were identified for each hip. Finally, the precision of the best possible anatomic reconstruction was assessed. Results The mean FO Anat was 38.0 mm (range: 19.8-57.9 mm, standard deviation [SD]: 6.4 mm), the mean NSA Anat was 130.8° (range: 107.1°-151.9°; SD: 6.5°), and the mean FH Anat was 32.6 mm (range: 14.4-52.0 mm; SD: 5.5 mm). In 450 (56.3%) hips, the standard variant was identified to be the best-fit implant, followed by the varus (n = 282, 35.3%) and the high offset (n = 68, 8.5%) variants. The mean minimal distance from the best-fit implant was 4.5 mm (range: 0.1-20.2 mm, SD: 3.4 mm). Excellent agreement (distance: Conclusion The present study revealed a mismatch between proximal femoral anatomy of a relevant proportion of adult hips and implant geometry of the most common femoral component in total hip arthroplasty.