Slightly better pain relief but more frequently motor blockade with combined nerve block analgesia compared to continuous intraarticular analgesia after total knee arthroplasty

Purpose Pain management after total knee arthroplasty (TKA) is still under debate. Continuous peripheral nerve blocks (PNB) can provide long pain relief but impair muscle function. Continuous intraarticular analgesia could result in longer pain relief than local infiltration analgesia without negative effects on muscle function. This study investigated the efficacy of pain control between PNB's and continuous intraarticular analgesia after TKA. Methods A prospective randomized study on 140 patients undergoing TKA was performed. Patients received either a combination of continuous femoral nerve block, continuous sciatic nerve block and single-shot obturator nerve block (group R) or a local infiltration analgesia and a continuous intraarticular catheter with ropivacaine (group L). Primary outcome was pain measured on a numerical rating scale. Knee function, patient-reported outcome (PRO) and adverse events were assessed until 1 year after surgery. Results Pain at rest was lower in group R on the day of surgery (mean NRS 3.0 vs. 4.2) and the morning of postoperative day 1 (mean NRS 3.4 vs. 4.4). Motor blockade longer than postoperative day 3 occurred more often in group R compared to group L (15.3% vs. 1.5%). Pain levels, PRO and satisfaction 3-month and 1-year after surgery were similar. Conclusion Continuous PNB's were slightly more effective in the first 24 h after surgery but were associated more often with motor blockade which should be avoided. It must be balanced if the small amount of better pain relief immediately after surgery justifies the risks associated with motor blockade following PNB's.