Intraoperative Fluoroscopy Versus Navigation to Determine Cup Anteversion in Direct Anterior Total Hip Replacement: A Technical Trick for Obtaining "True" Anteversion.

During acetabular cup positioning, intraoperative measurements of cup anteversion were taken using both fluoroscopy and navigation system. With the C-arm introduced at 40°, an anteroposterior view of the pelvis is taken. The C-arm is then centered over the hip, showing an anteverted cup with an approximate inclination of 40°. The axial C-arm is tilted away until the cup opening is visualized as a straight line, indicating that the beam of the fluoroscopy is aligned with the cup's anteversion. The tilt angle on the C-arm and anteversion reading on the navigation workstation were recorded. The high degree of agreement between fluoroscopic and navigation measurement of acetabular cup anteversion supports the use of fluoroscopy in settings with limited access to navigation systems in direct anterior total hip arthroplasty.