Study to describe the processing of ropivacaine in the body when injected in the knee for pain treatment in total knee arthroplasty.

Local infiltration analgesia (LIA) with ropivacaine for total knee arthroplasty (TKA) is increasingly used. Despite the high doses of ropivacaine, LIA is considered safe, and this perception is sustained by pharmacokinetic data demonstrating that maximum concentrations of ropivacaine stay well below the toxic threshold in plasma. These pharmacokinetic studies all involve TKA procedures with the use of a tourniquet. Recently, performing TKA without the use of a tourniquet is gaining popularity, but no pharmacokinetic data exist when LIA is administered for TKA without the use of a tourniquet. The purpose of this study was to describe the pharmacokinetic profile of a single-shot ropivacaine (200 mL 0.2%) and 0.75 mg epinephrine (1000 μg/mL) when used for LIA in patients for TKA without a tourniquet. In this prospective cohort study, 20 patients treated with LIA for TKA without a tourniquet are studied. Plasma samples are taken at 20, 40, 60, 90, 120, 240, 360, 480, 600, 720, and 1440 minutes after local anesthetic infiltration, in which total and unbound ropivacaine concentrations are determined.

not applicable

baseline, 20, 40, 60, 90, 120, 240 ,360, 480, 600, 720 and 1440 minutes after ropivacaine infiltration

bloodsamples 12 times 5-10 ml