Does total hip arthroplasty restore native hip anatomy? Three-dimensional reconstruction analysis

Purpose Component orientations and positions in total hip arthroplasty (THA) are important parameters in restoring hip function. However, measurements using plain radiographs and 2D computed tomography (CT) slices are affected by patient position during imaging. This study used 3D CT to determine whether contemporary THA restores native hip geometry. Methods Fourteen patients with unilateral THA underwent CT scan for 3D hip reconstruction. Hip models of the nonoperated side were mirrored with the implanted side to quantify the differences in hip geometry between sides. Results The study demonstrated that combined hip anteversion (sum of acetabular and femoral anteversion) and vertical hip offset significantly increased by 25.3 degrees +/- 29.3 degrees (range, -25.7 degrees to 55.9 degrees, p = 0.003) and 4.1 +/- 4.7 mm (range, -7.1 to 9.8 mm, p = 0.009) in THAs. Conclusions These data suggest that hip anatomy is not fully restored following THA compared with the contralateral native hip.