Standard Multimodal Postoperative Analgesia Might Not Be Equally Effective When Comparing Anterior and Posterior Spondylodesis

Abstract

Introduction. Surgical treatment of structural adolescent scoliosis, either through anterior or posterior spinal fusion, results in severe pain. Aim. In comparison with the anterior approach, the posterior approach is considered advantageous in that several spine curvatures can be corrected in a single operative act. The aim was to compare the effectiveness of a morphine-based multimodal protocol over the first 48 postoperative hours in anterior and posterior surgeries. Methods. This retrospective chart review included consecutive adolescents (10-21 years of age) treated using either the anterior (n=28) or the posterior (n=30) approach at a single hospital centre over 3 years (2015-2017). Intravenous morphine (48 mg/24 hours) was administered at hourly intervals; pain was assessed using an 11-point (higher score=worse pain) visual analogue scale on 12 occasions during the first 24 hours and on 3 occasions during the second 24 hours. Additional analgesia (non-opioid or weak opioid) was delivered on demand and/or according to medical assessment. Results. With adjustments for age and number of affected spinal segments, VAS pain scores were lower in the anterior approach, overall (48 hours) (difference = -18%, 95% CI -30 to -5), and particularly over hours 0-3 (-23%, 95% CI -36 to -7%) and hours 4-6 (-26%, 95% CI -40 to -10%) after the surgery. The rate of additional analgesic administrations was comparable throughout the observed period (rate ratios around 1.0). Conclusion. The evaluated intravenous morphinebased multimodal analgesic protocol appeared less effective in surgeries using the posterior approach, suggesting that the two approaches might require different protocols for the same level of analgesia.