Local infiltration analgesia versus interscalene nerve block for postoperative pain control after shoulder arthroplasty: a prospective, randomized, comparative noninferiority study involving 99 patients

Abstract

Background: The aim of this study was to compare the efficacy of local infiltration analgesia (LIA) and interscalene nerve block (ISB) for early postoperative pain control after total shoulder arthroplasty (TSA). The hypothesis was that LIA is not inferior to ISB.

Methods: A prospective, randomized controlled study was performed in 2014-2016. All patients who underwent TSA for shoulder osteoarthritis were included. Patients in the ISB group received a continuous infusion of 0.2% ropivacaine by perineural catheter for 48 hours. The surgeon injected 110 mL of 0.2% ropivacaine, 30 mg of ketoprofen, and 0.5 mg of epinephrine before TSA in the LIA group and inserted a catheter into the glenohumeral joint. The next morning, 10 mL of 0.2% ropivacaine, 30 mg of ketoprofen, and epinephrine were injected through the catheter, which was then removed. The primary outcome was the mean shoulder pain score for the 48-hour postoperative period on a numerical scale (0-10). The secondary outcomes were postoperative opioid requirements, complications, and shoulder function at the 1-month follow-up visit. The sample size was calculated for a noninferiority study.

Results: The study included 99 patients (50 LIA and 49 ISB patients) with a mean age of 72 ± 9.6 years. Although no significant difference in the mean pain score was found between the 2 groups for the 48-hour postoperative period (1.4 ± 0.9 for LIA vs 1.7 ± 1 for ISB, P = .19), the LIA group had significantly less severe pain (P = .003) and less opioid consumption (P = .01) in the recovery room. No complications occurred. A negative but nonsignificant correlation was found between postoperative pain and Constant score at the 1-month follow-up.

Conclusion: LIA is not less effective than ISB for early postoperative pain control after TSA.

Keywords: Total shoulder arthroplasty; early postoperative pain; interscalene nerve block; local infiltration analgesia; noninferiority study; opioid consumption.