LAUSR

Background The aim of this series was to investigate the efficiency of an intraoperative cell salvage system (ICS) removing metal ions during revision of metal-on-metal (MoM) devices to proof the possibility of re-transfusion of the collected blood. Materials and methods Between 2014 and 2018, five consecutive patients underwent revision surgery of their MoM total hip arthroplasty due to wear of the polyethylene-metal sandwich inlay or local massive metallosis with aseptic loosing of the cup. Aspiration of joint fluid of all hip prostheses was done and blood was taken to measure the metal ion concentrations, preoperatively. Perioperatively, blood was collected using an ICS before and after filtration and analyzed for Co and Cr concentrations. At that time, there was no re-transfusion of the collected and filtrated blood due to unknown metal ion concentrations. Results The mean preoperative serum Co and Cr concentrations in the blood were 31.28 μg/L (range 0.22–77.47) and 17.33 μg/L (range 0.59–51.31), whereas the mean local concentrations in the aspiration fluid were 728-fold and 822-fold higher. The Co and Cr concentrations measured in the collected blood before filtration were 70.61 μg/L (range 9.40–173.00) and 337.21 μg/L (range 8.76–1383.0) and decreased markedly to average concentrations of 15.49 μg/L and 41.88 μg/L, respectively. These differences were statistically not significant (Co: p = 0.117, Cr: p = 0.175), although the mean reduction rates were 78% and 88% for Co and Cr, respectively. Conclusion The current series showed that in case of revision of MoM hip devices, metal ions are still contained in the collected blood following filtration using a modern high-level ICS. Therefore, we would only recommend blood re-transfusion in case of low preoperative Co and Cr concentrations and sufficient renal function to warrant patients’ safety.