Ten-year Successful Results of Primary Total Knee Arthroplasty Using Cross-linked Polyethylene

Introduction: Highly cross-linked polyethylene (HXLPE) has been used for over a decade in total hip arthroplasty and has been shown to significantly reduce wear phenomena. At the knee, data are rare and the advantage of HXLPE inserts remains hypothetical because the stress regimen and wear mechanism are different. HXLPE has been accused of notwithstanding shear and peak compressive stresses. Our assumption was that the use of HXLPE would not compromise 10-year results compared to standard polyethylene. We asked whether[1] it would affect 10-year survival of primary total knee arthroplasty; [2] it would impair 10-year radiographic and clinical results. Methods: We examined 97 patients (Group 1) who underwent total knee arthroplasty with HXLPE (Durasul) over 10 years ago. These patients were retrospectively compared to 50 patients operated on in the same period using the same implant (Natural Knee 2, Zimmer) with standard polyethylene (sterilized in inert atmosphere) by other surgeons from the same institution (Group 2). Functional and radiographic results (from standard radiographs) were compared in terms of survival, clinical outcomes, and osteolysis. Sixty-four patients from Group 1 and 30 patients from Group 2 were examined with a follow-up of more than 10 years. Seventeen of Groups 1 and 12 in Group 2 died. Five and 14 patients, respectively, were lost. Results: 10-year survival rates, including revision for any cause, were 97 ± 3 and 91 ± 10%, respectively (P = 0.19). Two patients in Group 1 were reviewed due to instability and stiffness of the knee, and three patients in Group 2 were reviewed due to infection, instability, and patellar pain. Otherwise, the International Knee Society, Knee injury and Osteoarthritis Outcome Score, and mobility interval scores were not significantly different (P-values of 0.6, 0.7, and 0.7, respectively). None of the radiographs of the two groups showed osteolysis or widening radiolucencies. Conclusions: 10-year functional and radiographic results were not compromised by the use of HXLPE in cemented primary knee arthroplasty. On the other hand, the advantage of using HCLP in total knee arthroplasty is not yet proven. Longer monitoring and more accurate wear assessment are needed.