No abstract

Background: While providing effective analgesia following shoulder arthroplasty, an interscalene block has known complications. Local infiltration analgesia (LIA) using ropivacaine has been successfully employed in other joint arthroplasties, but its efficacy in shoulder arthroplasty has not been studied extensively. The purpose of this study was to compare pain and opioid consumption between LIA and an interscalene block following shoulder arthroplasty.Methods: Patients undergoing primary shoulder arthroplasty were prospectively randomized into 2 groups: the block group received an interscalene block using liposomal bupivacaine, and the injection group received an LIA injection intraoperatively. The LIA injection included ropivacaine, epinephrine, ketorolac, and normal saline solution. Postoperative visual analog scale pain scores, opioid consumption in morphine milligram equivalents, and complications were compared between the groups. The mean pain scores during the first 24 hours postoperatively were used to test noninferiority of LIA compared with an interscalene block. Results:The study included 74 patients (52 men and 22 women with a mean age of 69 years; 37 were in the injection group and 37 in the block group). There was no significant difference between the groups with respect to pain scores at any postoperative time points (p > 0.05), except for the 8-hour time point, when the injection group had a significantly higher pain score than the block group (p = 0.01). There was no significant difference in opioid consumption between the groups at any time points postoperatively (p > 0.05). The amount of intraoperative opioid consumption was significantly higher in the injection group (p < 0.001). In noninferiority testing for the mean pain scores during the first 24 hours, the injection group was found to be noninferior to the block group. One patient in the block group developed transient phrenic nerve palsy. One patient in the injection group developed dislocation after reverse arthroplasty related to noncompliance. The mean procedure hospital charge was $1,718 for an interscalene block and $157 for LIA.Conclusions: LIA and an interscalene block provided similar analgesia during the first 24 hours after primary shoulder arthroplasty. LIA was associated with worse pain at 8 hours postoperatively and more intraoperative opioid consumption but was also substantially less costly.