Methyl methacrylate levels in unwashed salvage blood following unilateral total knee arthroplasty.

To evaluate the safety of autologous reinfusion of drain blood in total knee arthroplasty (TKA), eight patients were prospectively evaluated to quantify levels of methyl methacrylate (MMA) monomer in systemic blood, and in their drain blood after unilateral cemented TKA. The systemic blood was analyzed before and after reinfusion of the drain blood. The drain blood was analyzed before reinfusion, and both before and after filtration through a 40-microm filter. A separate study was performed on 10 patients to assess the effect of blood, time, and filtration on MMA levels. Levels of MMA monomer in salvage blood were low enough to allow safe reinfusion. Systemic blood showed no evidence of MMA monomer either before reinfusion of salvage blood or at 5 minutes after reinfusion. Elimination of MMA is dependent on the time that MMA is exposed to blood and is independent of filtration.