Purpose of research The purpose of this study was to demonstrate that polyethylene (Vitamin E-containing polyethylene), a newly introduced biomaterial for tibial inserts in hip replacement surgery and widely used clinically, but whose mid- to long-term clinical results are still unknown, is superior to conventional polyethylene in vivo. The aim of this project is to conduct an international multi-center joint research study to determine whether polyethylene wear debris production can be reduced in the future, using an in vivo polyethylene wear debris analysis method that the investigators developed as a method that can provide early feedback.