Interleukin-1 beta levels from synovial aspirates were examined to determine if they can be used as indicators of increased synovial activity and an inflammatory reaction within total knee arthroplasty. Synovial aspirates were obtained from twelve osteoarthritic knees scheduled for total knee arthroplasty and twenty-one knees scheduled for total knee revision. Eleven of the revision cases involved titanium alloy prostheses and ten involved cobalt-chrome prostheses. Using a high sensitivity ELISA test kit, the interleukin-1 beta concentrations were compared. A significant difference in the interleukin-1 beta concentration was found between all three knee groups. The knees scheduled for revision surgery showed higher concentrations of interleukin-1 beta than osteoarthritic knees. While the knees implanted with a titanium prosthesis showed the greatest concentration of interleukin-1 beta, the osteoarthritic knees showed the lowest interleukin-1 beta concentration. Furthermore, significantly greater synovial aspirate volumes were obtained from the revision cases than from the osteoarthritic cases. This increased synovial activity is most likely attributed to the high concentration of the particulate wear debris produced from the prosthesis.