Safety of combined use of local anesthetic infiltration and reinfusion drains in total knee arthroplasty.

Injection of local anesthetic during total knee arthroplasty (TKA) has been shown to aid postoperative pain relief. Reinfusion drains have also proven useful in decreasing allogenic blood transfusion. Combined use carries the risk of reinfusion of local anesthetic from drainage bag. We examined plasma ropivacaine concentrations from 20 patients undergoing TKA, who were treated with these 2 techniques. Samples were taken from a dedicated venous cannula and from the reinfusion drainage bag. The average amount of ropivacaine reinfused was 1.9 mg, a fraction of the injected dose (150 mg), and venous plasma concentrations reached peaks of 0.5 to 1.5 microg/mL, well below demonstrated levels of toxicity. Patients tolerated the treatment well, with no adverse outcomes. This study demonstrates the safety of combining these 2 techniques in TKA.