Influence of obesity and intra-operative imaging guidance technology on acetabular cup positioning in total hip arthroplasty

Background Accuracy of acetabular cup positioning during total hip arthroplasty (THA) can be improved with intra-operative imaging but may be influenced by body mass index (BMI). This study assessed the influence of BMI (kg/m 2 ) on cup accuracy when using intra-operative fluoroscopy (IF) alone or supplemented with a commercial product. Methods This retrospective review included four consecutive cohorts of patients having undergone anterior approach THA with IF alone (2011–2015), IF and Overlay (2015–2016) (Radlink Inc., Los Angeles, CA), IF and Grid (2017–2018) (HipGrid Drone™, OrthoGrid Systems Inc., Salt Lake City, UT) and IF and Digital (2018–2020) (OrthoGrid Phantom®, OrthoGrid Systems, Inc., Salt Lake City, UT). Component placement accuracy was measured on 6-week post-operative weight bearing radiographs and compared between four BMI patient groups (BMI ≤ 25, 25