Characterization of submicron polyethylene wear debris from synovial- fluid samples of revised knee replacements using a light-scattering technique

The objectives of this study were to determine whether submicron-sized ultra-high-molecular-weight polyethylene (UHMWPE) wear debris was present in synovial fluid surrounding knee implants, and to report on the utility of a light-scattering technique for the in situ analysis of submicron-sized wear debris. The measured light-scattering coefficients of the implant synovial fluid samples were significantly larger than the coefficients of the control samples (p < 0.0001). The enhanced light scattering was attributed to the presence of submicron UHMWPE particles. This is consistent with light- scattering considerations and a Raman spectroscopy survey of synovial fluid. The mean particle volume fraction of UHMWPE was 1.11 x 10^-5 cm³/mL for the six implant samples, with mean particle diameters in the range of 200-300 nm. The UHMWPE volume fractions were found to differ by a factor of 2 between the osteolytic and nonosteolytic cases. The current findings warrant further work to determine the role of submicron polyethylene debris in the wear mechanisms of biomaterials and in the development of osteolysis following total knee replacement.