Abstract
Background Polyethylene wear-induced osteolysis is a major cause of implant loosening in total hip arthroplasty. New crosslinked polyethylenes are presumed to give lower wear rates, but no long-term clinical results are available yet.
Patients and methods We compared basic material characteristics and MTS hip joint simulator wear rates of a crosslinked polyethylene (Duration) to those of conventional polyethylene. In a randomized double-blind 5-year clinical follow-up study, 133 hips (67 conventional, 66 Duration) in 127 patients were followed-up for an average of 5 (3–6) years. Wear rates were measured using a computer-based edge detection method. The radiographic appearances of wear-related phenomena were recorded.
Results The Duration polyethylene showed a significantly lower in-vitro wear rate in the simulator study (mean 22 (SD 2.3) vs. 40 (SD 1.5) mm3/106 cycles). Also, the in-vivo wear was lower for Duration (mean 0.083 (SD 0.056) mm/year) than for conventional polyethylene (mean 0.123 (SD 0.082) mm/year). All radiographic signs of osteolysis were less frequent in the Duration group.
Interpretation Our study has given a substantial body of evidence—from lower wear rates, less frequent signs of osteolysis, and higher survival rates after a mean follow-up of 5 years—that Duration provides better clinical outcomes than conventional polyethylene.
Contributions of authors
CHG performed data analysis and wrote the manuscript. BG performed data analysis and gave statistical support. RR performed the wear simulator study and examined basic material properties. JJR operated patients in Zwolle. AJV operated patients in Sittard. AJT operated patients in Heerlen.