No advantage of adrenaline in the local infiltration analgesia mixture during total knee arthroplasty

Local infiltration analgesia (LIA) is widely applied in patients undergoing total knee arthroplasty (TKA). In daily practice, adrenaline is added to the LIA mixture to achieve vasoconstriction. However, adrenaline has some possible negative side effects (e.g. tissue necrosis). This trial investigated whether ropivacaine alone is at least as effective for postoperative pain relief after LIA.

Fifty patients scheduled for primary TKA were included in this prospective randomized, double-blind, controlled pilot study receiving high-volume (150 mL) single-shot intra-capsular LIA with ropivacaine (2 %) with (Ropi+) or without (Ropi−) adrenaline (0.01 %). All patients received the same pre-, peri- and postoperative care with multimodal oral pain protocol. Postoperative pain was assessed before and after the first mobilization and during the first 48 h postoperative using the visual analogue scale (VAS). Secondary outcomes were rescue medication use, early mobilization, length of hospital stay, adverse events (AE’s) and readmission rates. Patient reported outcomes measures (PROMS); Oxford Knee Score and WOMAC, were obtained preoperative and 3 months postoperative.

VAS scores were not significantly different before (n.s.) and after the first mobilization (n.s.), neither over the first 48 h postoperative (n.s.). Patients who needed rescue medication (n.s.), who mobilized <6 h postoperative (n.s.), who were discharged before postoperative day 3 (n.s.), AE’s and readmission rate (n.s.) were comparable between both groups. At 3-month follow-up, PROMS significantly improved within both groups.

To prevent possible negative side effects (e.g. tissue necrosis), adrenaline should be omitted from the LIA mixture. Single-shot LIA with ropivacaine alone results in clinical acceptable adequate pain control and can be used in daily TKA practice.

Randomized, double-blind, prospective clinical trial, Level I.