Linear and volumetric wear of tibial inserts in posterior cruciate-retaining knee arthroplasties.

Linear and volumetric wear was measured in 33 tibial polyethylene inserts from three different cruciate-retaining knee systems retrieved at the time of revision surgery. Wear patterns also were evaluated and classified. Eccentric and asymmetric wear patterns were seen in 78% of inserts with flat articulating geometry versus 12% in inserts with curved anteroposterior geometry. The mean linear wear rate was .35 mm/year (range, .05-1.68 mm/year) and the mean volumetric wear rate was 794 mm3/year (range, 24-4088 mm3/year). Linear and volumetric wear rates showed a negative correlation with the length of implantation. Linear wear rates also showed a negative correlation with patient weight.