The Importance of Modeling Press‐Fit to Accurately Evaluate Interfacial Micromotion as an Indicator of Primary Stability in Uncemented Arthroplasty

Arthroplasty is most often performed to alleviate pain and restore function in patients with end-stage degenerative joint disease. Uncemented implant fixation is increasingly used in total knee and total ankle arthroplasty. Implantation using interference press-fit is a manufacturer-recommended guideline for achieving stable primary fixation in uncemented applications, which is important to prevent long-term implant failure due to aseptic loosening. However, when evaluating implant-bone interfacial mechanics, many studies have not modeled press-fit implantation. This can lead to gross underestimation of primary implant fixation stability, limiting the clinical applicability of findings. The goal of this paper is to highlight the importance of simulating press-fit implantation when evaluating primary orthopedic implant stability using finite element analysis in uncemented arthroplasty. Experiences gained in modeling press-fit implantation in total knee and total ankle arthroplasty by two different active research groups are shared in this context.