To our knowledge, there has been no information on in vivo clinical results of posterior cruciate-substituting arthroplasties using highly cross-linked polyethylene. We evaluated whether the clinical and radiographic results, incidence of post fracture of the tibial polyethylene insert, failure of the locking mechanism of the tibial polyethylene insert, and the incidence of osteolysis would be similar between posterior cruciate-substituting total knee prostheses using conventional and highly cross-linked polyethylene.