Activity level and wear in total knee arthroplasty: a study of autopsy retrieved specimens.

We assessed the correlation between activity level, length of implantation (LOI), and wear in total knee arthroplasty. Twenty-eight implants were retrieved at autopsy from 8 men and 15 women. Linear, volumetric, and visual wear and the presence or absence of creep were quantitated. Functional level was classified using the Knee Society, the standard Charnley classification, and the UCLA activity level scale. The average age at surgery was 68 years +/- 14.0 SD and average LOI was 74 months +/- 38 SD. The average linear and volumetric wear rates were 0.127 mm/y +/- 0.104 SD and 31.80 mm3/y +/- 42.8 SD. LOI (B coefficient = -0.656 +/- 0.0 SE; P<.001) correlated with linear, volumetric, and visual wear rates. Charnley C patients showed decreased volumetric wear in the lateral compartment (P=.01). Decreased activity level (UCLA) correlated with areas of less extent and severity of creep (P=.001 and P<.001).