Tailor-made surgical guide based on rapid prototyping technique for cup insertion in total hip arthroplasty

Background A surgical guide made by the rapid prototyping (RP) technique for cup insertion in total hip arthroplasty might be useful to avoid malalignment of the cup, which indicates postoperative complications. Methods To address this research question, we applied a RP-based guide to 24 patients with their CT images. We designed it to fit onto the acetabular edge and to insert a Kirschner wire (K-wire) which indicated a planned cup direction. We intraoperatively placed it on the acetabular edge, inserted the K-wire through the guide on the superior acetabulum and implanted the cup while observing the alignment of the K-wire. We also recorded the additional time needed to use the guide. Results The mean cup accuracy between planned and postoperative alignments was 2.8 degrees (SD = 2.1 degrees) for abduction and 3.7 degrees (SD = 2.7 degrees) for anteversion. The mean additional time was 3.5 (range 2-6) min. Conclusion We can use this guide with acceptable accuracy and without consuming an excessive amount of time. Copyright (C) 2009 John Wiley & Sons, Ltd.