Continuous intra-articular infusion of bupivacaine for post-operative pain relief after total hip arthroplasty: a randomized, placebo-controlled, double-blind study.

BACKGROUND: Instillation of local anesthetics into a surgical site has been gaining popularity in post-operative pain management.

AIM: To determine whether continuous intra-articular infusion of bupivacaine via pain-control infusion pumps (PCIP) enhances and sustains analgesia after total hip arthroplasty (THA).

METHODS: Ninety-two patients undergoing THA were randomized to receive continuous intra-articular infusion of either 0.5% bupivacaine or 0.9% normal saline at a flow rate of 2 mL/h via a PCIP for 48 h. The primary outcome measure was pain intensity on Visual Analogue Scale (VAS) scores in the first 72 h. Other measures included time to first rescue dose of narcotics, amount of narcotic use, presence of adverse events, length of hospital stay, and hip function evaluated with the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index.

RESULTS: Despite a longer time to first narcotic rescue (56 versus 21 min, p<0.0001) in patients receiving bupivacaine, the two groups did not differ significantly in overall pain relief (p=0.54). A lower VAS score was found only at time 0 and 2 h; no difference in VAS score was noted at any other time point. Additionally, no difference was found in terms of amount of narcotic use, incidence of adverse events, hospitalization days, and the WOMAC score.

CONCLUSION: Continuous intra-articular infusion of 0.5% bupivacaine at 2 mL/h via a PCIP does not provide sustained post-operative pain relief in patients undergoing THA.