Efficacy of Intraoperative Intra-Articular Morphine on Post-Operative Pain and Opioid Consumption Following Hip Arthroscopy

Background: The use of intraoperative intra-articular morphine has been suggested to lower postoperative pain scores and opioid use. We sought to evaluate the effectiveness of intra-articular morphine with 0.75% ropivacaine when compared to the use of ropivacaine alone. Our study's purpose was to determine the efficacy of intra-articular morphine on pain control, opioid consumption, and discharge times in the immediate post-operative period.

Methods: We retrospectively reviewed the charts of 100 patients who underwent hip arthroscopy with repair for femoroacetabular impingement (FAI) between 2021 to 2023. 50 patients who received 5 mg of intra-articular morphine injections intraoperatively were identified, and 50 who did not. Patients undergoing hip arthroscopy without repair, revision surgery, or combined hip arthroscopy and femoral osteotomy or periacetabular osteotomy were excluded. Demographics including age, sex, race, ethnicity, BMI, and tobacco use were recorded. Procedural factors included total operative time, traction time, and time to discharge. Pain scores were assessed using the Visual Analog Scale (VAS), and the initial Post-Anesthesia Care Unit (PACU) and final VAS score prior to discharge were recorded. Total acute opioid use was recorded using morphine milligram equivalents (MME) during post-operation to discharge. We used the Wilcoxon rank sum test and chi-square statistics on continuous and categorical variables, respectively. Statistically significant level was set as p<0.05.

Results: No significant differences were found between demographics, operative time, traction time, or discharge time. The median age of patients in the non-morphine group was 29 (48% M, 52% F) and 24.5 (34% M, 66% F) in the morphine group. Differences between the morphine and non-morphine group in postoperative VAS scores were insignificant, with the mean initial PACU VAS scores (4.6 ± 3.0 vs 5.5 ± 3.0) and mean final PACU VAS scores (3.5 ± 1.9 vs 3.7 ± 1.4) respectively. Postoperative MME consumption difference was also insignificant (17.1 ± 7.4 vs 17.9 ± 7.3).

Conclusion: Intraoperative intra-articular morphine injection with ropivacaine does not provide a significant reduction in acute postoperative pain scores or opioid use when compared to ropivacaine use alone. Further investigation into the efficacy of intra-articular morphine is warranted. Level of Evidence: III.