Influence of orthopedic particulate biomaterials on inflammation and synovial microcirculation in the murine knee joint.

The purpose of the present study was to examine changes in the synovial microcirculation as well as synovial tissue responses to exposure to titanium, polymethylmethacrylate (PMMA), ceramic (Al(2)O(3)), cobalt-chromium alloy (Co-Cr), and polyethylene (PE) particles in an in vivo model. The particulate biomaterials were injected into the left knee joint of female Balb/c mice and assessment of the synovial microcirculation using intravital fluorescence microscopy as well as histological evaluation of the synovial tissue response were performed on day 7 after particle administration. Intravital microscopic measurements revealed that all tested biomaterials caused significantly (p < 0.05) enhanced leukocyte-endothelial cell interactions and an increase of functional capillary density compared to controls. In the histological examination PMMA, Al(2)O(3), PE, and Co-Cr particles provoked significantly (p < 0.05) enhanced inflammatory tissue responses in comparison to tissue from control animals. Titanium particles showed significantly (p < 0.05) less leukocyte-endothelial cell interactions than the other particulate biomaterials and caused significantly (p < 0.05) minor membrane thickening compared to PE and PMMA particles. In conclusion, all tested particulate biomaterials were capable of inducing inflammatory responses in the present study. Our data suggest that titanium particles may cause less leukocyte activation and inflammatory tissue responses than other particulate biomaterials used in total joint arthroplasty.