Alignment and mechanics evaluation for a compaction broach stem versus a blade style proximal press fit stem using 3-Dimensional planning.

Three-dimensional (3D) preoperative planning tools can be used to help plan and compare component alignment scenarios for different total hip arthroplasty systems to ultimately improve postoperative outcomes and patient satisfaction. The objective of this study is to use 3D preoperative planning tools based on patient-specific bone models to compare two different stem designs, specifically a compaction broach stem and a proximal press fit stem. The planner uses patient-specific proximal femoral bone morphology to suggest a specific implant size and placement. The planner then allows for preoperative predictions of component head positioning, stem fit within the canal, and potential cortical bone reaming that must be done, as well as postoperative predictions of stability and mechanics. The stems were evaluated to determine the accuracy of stem placement, the theoretical volumetric bone removal/reaming required to achieve a desired fit, and the associated postoperative mechanics. This study demonstrated that there was a difference in component alignment and predicted postoperative mechanics between a compaction broach stem and a press fit stem, with the compaction broach stem allowing for more accurate alignment with less required bone removal, resulting in improved postoperative stability and mechanics. This study also demonstrated that much of the stem misalignment for both systems occurred in the anterior/posterior direction. Overall, 3D preoperative planning offers significant benefits and novel intraoperative insight, and the industry should continue to enhance their THA preoperative planning tools.