Periarticular injection in addition to interscalene nerve block can decrease opioid consumption and pain following total shoulder arthroplasty: a comparison cohort study.

Abstract

Interscalene nerve block (INB) is an effective technique to provide postoperative analgesia for total shoulder arthroplasty (TSA). However, the analgesic effects of the block typically resolve between 8 and 24 hours postadministration, which results in rebound pain and subsequent increased opioid use. The objective of this study was to address this issue by determining how adding an intraoperative periarticular injection (PAI) in combination with INB affects acute postoperative opioid consumption and pain scores in patients undergoing TSA. We hypothesized that compared with INB alone, INB+PAI will significantly reduce opioid consumption and pain scores for the first 24 hours postsurgery. We reviewed 130 consecutive patients who underwent elective primary TSA at a single tertiary institution. The first 65 patients were treated with INB alone, followed by 65 patients treated with INB+PAI. The INB used was 15-20 mL of 0.5% ropivacaine. The PAI used was 50 mL of a combination of ropivacaine (123 mg), epinephrine (0.25 mg), clonidine (40 μg), and ketorolac (15 mg). The PAI was injected using a standardized protocol: 10 mL into the subcutaneous tissues prior to incision, 15 mL into the supraspinatus fossa, 15 mL at the base of the coracoid process, and 10 mL into the deltoid and pectoralis muscles-a protocol analogous with a previously described technique. For all patients, a standardized postoperative oral pain medication protocol was used. The primary outcome was acute postoperative opioid consumption represented by morphine equivalent units (MEUs), whereas the secondary outcome was visual analog scale (VAS) pain scores over the first 24 hours postsurgery, operative time, length of stay, and acute perioperative complications. No significant differences in demographics existed between patients who received INB alone vs. INB+PAI. Patients who received INB+PAI had a significantly lower 24-hour postoperative opioid consumption compared to the INB alone group (38.6±30.5 MEU vs. 60.5±37.3 MEU, P<.001). Additionally, VAS pain scores for the first 24 hours postsurgery in the INB+PAI group were significantly lower compared to those for the INB alone group (2.9±1.5 vs. 4.3±1.6, P ≤ .001). No differences existed between groups regarding operative time, length of inpatient stay, and acute perioperative complications. Patients undergoing TSA with INB+PAI demonstrated significantly decreased 24-hour postoperative total opioid consumption and 24-hour postoperative pain scores compared to the group treated with INB alone. No increase in acute perioperative complications related to PAI was observed. Thus, compared to an INB, the addition of an intraoperative periarticular cocktail injection appears to be a safe and effective method to reduce acute postoperative pain following TSA.