<h3>BACKGROUND CONTEXT</h3> Posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS) is a complex procedure for which charges can exceed $150,000. Among the total costs, inpatient and intensive unit care contributed 22%. Many institutions have implemented rapid recovery pathways (RRP) to improve patient care following scoliosis surgery. Most RRPs encourage early ambulation, feeding, and stooling in combination with patient-controlled analgesia (PCA). <h3>PURPOSE</h3> This study aims to determine the effects of a multimodal RRP, utilizing intrathecal morphine (ITM) in combination with oral pain medication, on hospital costs and patient management. <h3>STUDY DESIGN/SETTING</h3> Retrospective review. <h3>PATIENT SAMPLE</h3> AIS patients undergoing posterior spinal fusion between 2013 and 2019. <h3>OUTCOME MEASURES</h3> Surgical outcomes and associated costs. <h3>METHODS</h3> Patients after February 2018 were placed in the RRP group. These patients received ITM as part of their multimodal analgesia. Fusion level-matched control patients, treated before February 2018, received hydromorphone PCA as the mainstay of their postoperative pain management. At discharge PCA patients received 14-day prescriptions for oxycodone compared to 7-day prescriptions in the ITM group. Perioperative data, requests for opioid refill, and overall costs were compared using McNemar's and Wilcoxon Signed-Rank tests. <h3>RESULTS</h3> A total of 363 patients were included (PCA: 255, RRP/ITM: 108). BMI (p = 0.786) and median preoperative Cobb angle (p = 0.343) were similar between both groups. RRP patients had a significantly shorter length of stay (3 days vs 5 days, p <0.001) and 65.2% of RRP patients ambulated by postoperative day (POD) 1 compared to 43.4% of PCA patients (p < 0.001). The fraction of patients who requested opioid refills was similar between both groups (p = 0.082). The cost of intraoperative anesthesia was significantly higher for RRP patients ($2,286.87 v $1,958.70, p<0.001). Perioperative hospital stay ($39,990.00 vs $55,680.00, p<0.001) was significantly lower for the RRP patients. Due to different prescription durations, the cost of home opioid medications was $98.94 for PCA patients vs $56.28 for RRP, based on standard Medicaid costs. <h3>CONCLUSIONS</h3> The RRP protocol following PSF had lower total hospital costs and lower home opioid requirements after surgery than the traditional PCA protocol. <h3>FDA DEVICE/DRUG STATUS</h3> intrathecal morphine, oxycodone: Approved.