O2073: Preoperative Intrathecal Morphine Injection is Superior in Terms of Pain Control when Compared to a Post-Incisional Injection

Background: Intrathecal morphine (ITM) has become a widely used adjunct in pediatric scoliosis surgery due to its benefit in decreasing narcotic use and improving pain scores. While optimal dosages and formulations have been described, it is unclear whether administration should be pre- or post-incision.

Methods: Patients with AIS undergoing primary instrumentation and fusion by three senior attendings between 2018 – 2022 were included. 400 patients met inclusion criteria, with 205 receiving intrathecal morphine pre-incision by the anesthesia team and 195 receiving intrathecal morphine by the surgeon at the time of closure. Outcomes measured include maximum pain score (POD 0 – 2), time to OOB, LOS, packed red blood cell (pRBC) transfusions, complications, narcotic refills, and morphine consumption at various timepoints. Kruskal-Wallis and Chi-Squared tests were used in data analysis to determine statistical significance. Patients in the ITM group were further divided into those who underwent concurrent rib-resectioning during their PSF and those that did not.

Results: The demographics of the study groups demonstrated no significant differences. Max pain scores were significantly lower in the group receiving intrathecal morphine pre-incision (7.0 vs 8.0, p = 0.047). When looking at individual postoperative days, patients experienced similar pain scores at activity for POD 0, POD 1, and POD 2 (p= 0.29, p= 0.88, and p= 0.23, respectively). OOB and LOS did not show any significant differences between groups. However, the pre-incision group used significantly less morphine during the 24–48-hour post-op period (p= 0.02) and less total morphine overall (p= 0.02). There were no observed differences in transfusion, narcotics refilled, or total complications between groups. There were no differences seen in our analysis on rib resectioned patients compared to patients that did not undergo rib resectioning.

Conclusion: Intrathecal morphine administered pre-incision leads to better and more predictable pain control in AIS patients undergoing instrumented PSF. Furthermore, ITM is effective in controlling post-operative pain even when an additional painful procedure, such as rib-resectioning, is done.