Risk factors of liposomal bupivacaine failure in managing postoperative pain following shoulder surgery

Amidst a national opioid crisis, increased focus has been placed on reducing opioid consumption. Novel multimodal pain protocols, including the use of liposomal bupivacaine (LB) have shown success in minimizing opioid usage after orthopedic surgery. There is disputing evidence of the effectiveness of LB use in shoulder surgery and the purpose of our study was to analyze the risk factors and determinants of LB failure for postoperative pain control after orthopedic shoulder surgeries. A retrospective review of 121 patients undergoing shoulder surgery treated by two fellowship trained shoulder surgeons at a single institution was performed from 2018-2020. All patients received a standardized multimodal pain management protocol that included an LB interscalene block. Local infiltration of LB was also administered at closure. Visual analog scales (VAS) were administered at 24, 48, 72 hours, and 7 days postoperatively. LB failure was defined as VAS score >7 any time within the 7-day postoperative period. Twenty-one patients were included in the liposomal bupivacaine failure (LBF) group and 100 in the liposomal bupivacaine success (LBS) group. Patient demographics, pain scores, and opioid consumption were compared between groups. Baseline characteristics were comparable, except the LBF cohort had a greater proportion of females (p=0.03). The LBF group had 20% of patients with a history of chronic opioid use compared to none in the LBS group (p=0.003). Logistic regression showed strong and independent associations between failure of LB and performing surgeon, chronic opioid use, gender, and history of prior surgery. Patients in the LBF group had an average of 20 Total Morphine equivalents (TME) 7-14 days following surgery compared to 0 TME (p=0.002) in the LBS group, and an average of 2.9 opioid prescriptions within the first 6 months compared to 1.7 in the LBS group (p=0.028). Performing surgeon, gender, history of opioid use, and prior surgeries were all identified as strong, independent predictor variables of LB failure. In this study, performing surgeon is likely indicative of the impact of differences in patient education on postoperative pain expectations and alternate treatments. We recommend that surgeons incorporate further preoperative patient education, and to take into account the specific risk factors when deciding to incorporate LB into their multimodal postoperative pain management plan for patients undergoing shoulder surgery.