Polyethylene insert backside surface wear is implicated in osteolysis and failure of total knee arthroplasty. Manufacturing
and sterilization methods reduce articular-sided wear. We questioned whether manufacturing technique influences the severity
of backside wear. We examined 39 explanted tibial bearings in a blinded fashion using visual, stereomicroscopic, and scanning
electron microscopic techniques. We examined 26 direct compression molded components and 13 nondirect compression molded components
and applied a new backside wear severity score. The score characterized the magnitude of the various modes of wear with severity
ranging from 0 (no wear) to 27 (severe wear). Time in vivo, tibial baseplate material, and manufacturing technique were used
as variables for comparison. Backside wear was related to polyethylene manufacturing process with direct compression molded
implants having a wear score of 2.3 and nondirect compression molded a score of 5.7. Time in vivo influenced backside wear,
although direct compression molded predicted decreased backside wear independent of time in vivo. The data suggest manufacturing
technique influences backside wear in total knee arthroplasty polyethylene inserts.
One or more of the authors (AVL, KRB) has received institutional research funding, consulting income, and/or royalties from
a commercial interest related to the subject of the manuscript (Biomet, Inc). One or more of the authors (BSE) has received
institutional research or grant funding from the Ohio State University Department of Orthopaedics in support of this research.
Each author certifies that his institution has approved the human protocol for this investigation, that all investigations
were conducted in conformity with ethical principles of research, and that informed consent for participation in the study
was obtained.