Human Plasma Adsorption to Particulate Arthroplastic Component Materials In Vitro

A preliminary study of the adsorption of plasma proteins to four commonly used arthroplastic materials was performed. Particulate forms of titanium, cobalt, chromium, and polymethyl methacrylate (PMMA) were incubated with plasma from patients undergoing primary arthroplastic surgery and from patients undergoing revision surgery. The adsorbed proteins were eluted with 2% sodium dodecyl sulfate (SDS) and were separated electrophoretically on Laemmli minigels. The separated protein bands were clustered into five groups based on their molecular weights: <144, 144 to 77, 76 to 43, 42 to 18, and >18 kilodaltons (kD). The number of bands in each group was used as a way of comparing the patterns of adsorption to the different biomaterials. The number of eluted protein bands in the 77 to 145-kD range for cobalt (2.4 ± 1.34 bands) was less than that eluted from titanium (4.40 ± 0.89 bands) and from chromium (4.20 ± 0.045 bands) for both primary and revision plasma. Fewer protein bands were also eluted from cobalt than from chromium, PMMA, and titanium in the 18 to 42-kD range. The authors speculate that, because of cobalt's unique surface characteristics, plasma proteins may show either enhanced or impaired binding. Although this remains to be demonstrated, the results of this study define trends that warrant further investigation.