Intraarticular analgesia versus epidural plus femoral nerve block after TKA: a randomized, double-blind trial.

BACKGROUND: Pain management after TKA remains challenging and the efficacy of continuously infused intraarticular anesthetics remains a controversial topic.

QUESTIONS/PURPOSES: We compared the side effect profile, analgesic efficacy, and functional recovery between patients receiving a continuous intraarticular infusion of ropivacaine and patients receiving an epidural plus femoral nerve block (FNB) after TKA.

METHODS: Ninety-four patients undergoing unilateral TKA were prospectively randomized to receive a spinal-epidural analgesic infusion plus a single-injection FNB or a spinal anesthetic plus a continuous postoperative intraarticular infusion of 0.2% ropivacaine. All patients were blinded to their treatment with placebo saline catheters. Blinded coinvestigators collected data concerning side effect profiles (nausea, hypotension), analgesic efficacy (VAS pain scores, narcotic usage), and functional recovery (timed up and go test, quadriceps strength, WOMAC scores, Knee Society scores, early postoperative ambulatory ability, in-hospital falls). All complications and adverse events were recorded.

RESULTS: The frequency of nausea and hypertension was not different between the study groups. During the first 12 and 24 postoperative hours, the mean maximum VAS pain scores were higher in the ropivacaine group than in the epidural group (first 12 hours: 3.93 versus 1.14, respectively, p < 0.0001; 12-24 hours: 3.52 versus 1.93, respectively, p = 0.008). After 24 hours, pain scores were similar between groups. Narcotic consumption was significantly higher in the ropivacaine group on the day of surgery, but overall in-hospital narcotic usage was similar between groups. There were no clinically important differences in functional recovery between groups at any time point, but patients in the epidural group were more likely to have knee buckling (32.7% versus 6.7%, p = 0.002) and delayed ambulation (16.3% versus 0.0%, p = 0.006) than patients in the ropivacaine group, though not in-hospital falls. No infections occurred in either group, and the frequency of complications was not different between groups.

CONCLUSIONS: A continuous intraarticular infusion of ropivacaine can be recommended as a safe, effective alternative to epidural analgesia plus single-injection FNB after TKA. Improved analgesic efficacy in the group that received epidural analgesia plus single-injection FNB must be weighed against the disadvantage of a higher likelihood of knee buckling and delayed ambulation with that treatment approach.

LEVEL OF EVIDENCE: Level I, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.