Acetabular Home Run Screw Guidance for Transiliac Fixation in Cup Revision Arthroplasty

Background/Objectives: The growing incidence of acetabular revisions has highlighted the importance of achieving reliable fixation to the remaining bone. Proximal transiliac fixation (TIF) of pelvic implants is becoming an increasingly common approach for managing extensive bone defects. This study seeks to provide guidance on TIF implantation by analyzing the optimal screw placement in partial pelvic replacements for acetabular defects. Methods: Between 2014 and 2024, a cohort of 96 consecutive patients (65 females and 31 males) who underwent customized partial pelvic replacement (PPR) with transiliac fixation (TIF) were examined. The angle and entry point of the ideal TIF were determined using preoperative three-dimensional planning and compared with potential influencing factors. Results: All PPRs were successfully implanted, with an average TIF length of 77 mm. The mean anteroposterior angle for TIF was 18° medially and 27° dorsally. Conclusions: Analysis of the entry point showed concentration around the second radius and between the eleven o'clock and one o'clock positions. The AP angle is notably affected by gender and height. Considering the precision of human judgment, a recommendation for TIF placement would be 20° medial and 30° dorsal deviation, with the entry point around the twelve o'clock position and the second ring from the center of the cup.