Crosslinked polyethylene compared to conventional polyethylene in total hip replacement: pre-clinical evaluation, in-vitro testing and prospective clinical follow-up study.
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.


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.


CONCLUSIONS
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.
Geerdink
Carel H
CH
Department of Orthopaedic Surgery, Atrium Medisch Centrum, Heerlen, CX, NL-6401, the Netherlands. carelgeerdink@hotmail.com
Grimm
Bernd
B
Ramakrishnan
Rama
R
Rondhuis
Jorco
J
Verburg
Aart J
AJ
Tonino
Alphons J
AJ
D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000379:methods; D001696:Biomechanical Phenomena; D003432:Cross-Linking Reagents; D005271:Femur Head Necrosis / Q000601:surgery; D005500:Follow-Up Studies; D006622:Hip Prosthesis / Q000009:adverse effects; D006801:Humans; D066298:In Vitro Techniques; D008422:Materials Testing; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000601:surgery; D010014:Osteolysis / Q000209:etiology; D011095:Polyethylenes / Q000009:adverse effects; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure; D013997:Time Factors
D003432:Cross-Linking Reagents; D011095:Polyethylenes