Evaluation of Implant Positioning Alignment in Medial Unicompartmental Knee Arthroplasty

Unicompartmental knee arthroplasty (UKA) is a kind of minimally invasive surgery (MIS), which has relatively small scarring, short recovery time, and greater postoperative range of motion. UKA has therefore become the trend of arthroplasty in recent years, and it has been widely accepted by patients with unilateral joint damage. However, there are problems under the surging demands for UKA, such as the selection of patients, knee prostheses and surgical method. Because these factors have great impacts on the surgical outcomes, it is critical to explore the influence of unicompartmental knee prostheses (UKP) in various alignments. This study employs the finite element analysis (FEA) to evaluate the effects of UKP on the polyethylene (PE) components in various implant alignments, and thus provides further information for clinical practices. The results show that UKP has considerable impact upon the wear of the PE tibial components under conditions such as joints overuse, overweight or undercorrection of varus deformity. In addition, this study evaluates the angle after correction of the varus deformity, and results show that the angle should be less than 10deg, otherwise the wear of the lateral side of the PE tibial components will increase and thus shorten the expectancy of joint protheses.