Impact of Morphine on Early Recovery After Anterior Cruciate Ligament Reconstruction: A Case-Control Study

Purpose: Effective pain management is crucial in postoperative recovery after Anterior Cruciate Ligament Reconstruction (ACLR).To examine the effectiveness of the new opioid-containing protocol compared to another previously published protocol based on Nefopam and dynamic compression cryotherapy.Methods: This retrospective analysis of prospectively collected data was conducted at a sports surgery center between 2023 and 2024, including 1116 patients undergoing primary isolated ACLR.Patients were divided into two matched groups based on postoperative pain management: the opioid group (N=556), treated with oral morphine sulfate (Actiskenan®) as needed in addition to multimodal analgesia (e.g., paracetamol, nefopam, and ketoprofen), and the non-opioid group N=556, treated with multimodal analgesia alone.Patients were matched for age, sex, BMI, Lysholm score, Tegner score, meniscal injury, and chondropathy.The primary outcome was pain on the visual analogue scale (VAS) in the early postoperative period, analyzed in relation to the minimal clinically important difference (MCID) and the patient acceptable symptom state (PASS) thresholds for VAS.The secondary outcome was side effects, including nausea, dizziness, vomiting, anxiety, and abdominal pain, as well as early complications and revision rate.Results: The mean age in both groups was comparable (32.2 ± 9.4 years in the non-opioid group [N = 556] and 32.5 ± 10.0 years in the opioid group [N = 556], p = 0.867).Both groups predominantly used the quadrupled hamstring graft technique (440/556, 80.0% vs. 438/556, 79.9%, p = 0.4455).Preoperative scores were similar (p > 0.05).Postoperative pain was higher in the non-opioid group: day 0 VAS scores were 5.6 ± 2.7 (n = 536/556) vs. 5.3 ± 2.7 (n = 522/556) (p = 0.0339), and night pain was more common (379/556, 68.2% vs. 341/556, 61.3%, p = 0.0202).This trend continued on day 1 (5.2 ± 2.4 [n = 545/556] vs. 4.8 ± 2.4 [n = 543/556], p = 0.0014), day 2 (4.5 ± 2.4 [n = 551/556] vs. 4.2 ± 2.3 [n = 550/556], p = 0.0182), and day 3 (3.8± 2.3 [n = 551/556] vs. 3.4 ± 2.2 [n = 551/556], p = 0.0080).The non-opioid group had higher rates of dizziness on day 0 (100/536, 18.7% vs. 70/522, 13.4%, p = 0.0236).There was a trend toward higher complications in the non-opioid group (11/556, 2.0% vs. 3/556, 0.5%, p = 0.0558), mainly due to Cyclops syndrome and knee stiffness.Reoperation rates were similar (p > 0.05).Conclusion: Adding morphine to the postoperative protocol was associated with reduced postoperative pain in the first 3 days postoperatively and dizziness on the first day.However, while statistically significant, the mean difference in VAS scores did not exceed the MCID.