Knee-simulator testing of conventional and cross-linked polyethylene tibial inserts.
We compared the resistance to delamination and to adhesive/abrasive wear of conventional and highly cross-linked polyethylene tibial inserts of a cruciate-retaining total knee design using a knee simulator. Both groups were tested after aggressive, accelerated aging, and 1 set of conventional inserts was studied without aging. Aging oxidized the conventional, but not the highly cross-linked, inserts. The simulated normal gait testing lasted for 5 and 10 million cycles for the conventional and highly cross-linked inserts, respectively. Aged conventional inserts showed delaminations, whereas none were observed in the unaged conventional and aged cross-linked inserts. Wear rates measured by the gravimetric method were 9 +/- 2 mm3, 10 +/- 4 mm3, and 1 +/- 0 mm3 per million cycles; by the metrologic method, they were 8 +/- 1 mm3, 9 +/- 2 mm3, and 3 +/- 0 mm3 for the unaged conventional, aged conventional, and aged highly crosslinked inserts, respectively. In the test model used, oxidation led to delamination, whereas increased cross-link density resulted in reduced adhesive/abrasive wear of tibial inserts.
Orthopaedic Biomechanics and Biomaterials Laboratory, Massachusetts General Hospital, Boston 02114, USA.
Orhun K
OK
Muratoglu
Charles R
CR
Bragdon
Murali
M
Jasty
Daniel O
DO
O'Connor
Rebecca S
RS
Von Knoch
William H
WH
Harris
D019544:Equipment Failure Analysis; D006801:Humans; D007720:Knee Prosthesis; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010084:Oxidation-Reduction; D011095:Polyethylenes; D011475:Prosthesis Failure; D012399:Rotation; D013314:Stress, Mechanical; D013499:Surface Properties
D011095:Polyethylenes