Wear of prosthetic joint materials in various lubricants

As a part of ongoing research intended to produce a reliable artificial joint fluid for wear tests of prosthetic joint materials, the lubricating properties of soybean lecithin and soy protein were studied. For comparison, wear tests were done with bovine serum, and with joint fluid aspirated from a prosthetic hip joint at revision operation. The tests were done with ultrahigh molecular weight polyethylene sliding against polished stainless steel and Co-Cr alloy. In the reciprocating pin-on-disk device, lecithin in distilled water and in phosphate buffer did not completely prevent the polyethylene transfer to the polished stainless steel counterface. Soy protein in salt solution had excellent lubricating properties: it prevented polyethylene transfer and the wear of the polyethylene pin. Bovine serum suppressed polyethylene transfer and all other damage to the stainless steel counterface. The prosthetic joint fluid had poor lubricating properties, similar to those of distilled water. In the three-axis hip simulator test, lecithin in Ringer's solution prevented the polyethylene transfer to the Co-Cr femoral head. (C) 1997 Elsevier Science S.A.