Journal of Pediatric Orthopaedics - 2026-07-09 - Journal Article
The Effect of Liposomal Bupivacaine and Obesity on Postoperative Opioid Consumption in Children With Scoliosis.
Ogu E, Lima JM, Thornberg D, McLeod C, McIntosh A, Ramo B, Jo CH, Brooks JT
Topics
Key Takeaway
Obese AIS patients undergoing PSF with liposomal bupivacaine consumed significantly less total inpatient opioid (β=-0.50, P=0.0001) than healthy-weight peers, with increasing BMI percentile negatively correlated with total MME/kg (ρ=-0.182, P=0.012).
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Summary
This single-institution retrospective cohort evaluated whether obesity attenuates liposomal bupivacaine's analgesic efficacy in AIS patients aged 10–19 undergoing PSF, stratifying 190 patients by BMI percentile and quantifying opioid use in MME/kg. Contrary to the hypothesis, obese patients consumed significantly less total inpatient MME/kg than healthy-weight patients (β=-0.50, P=0.0001), with the association persisting after multivariable backward selection. Pain scores, SRS-30 outcomes, and pain catastrophizing scores did not differ across BMI groups, suggesting equivalent subjective pain control despite lower opioid consumption in obese patients.
Key Limitation
Absence of a non-liposomal bupivacaine control group makes it impossible to determine whether the obesity-associated opioid reduction is attributable to LB pharmacokinetics or to baseline differences in opioid sensitivity and prescribing patterns in obese children.
Original Abstract
BACKGROUND
Liposomal bupivacaine (LB) is increasingly used in multimodal pain management protocols for the treatment of adolescent idiopathic scoliosis (AIS) with instrumented posterior spinal fusion (PSF), yet its efficacy in obese pediatric populations remains unclear. Obesity is associated with increased pain burden, potentially diminishing LB's analgesic benefits. Therefore, the purpose of this study is to evaluate postoperative opioid consumption in AIS patients treated with LB.
METHODS
We conducted a retrospective cohort study of AIS patients aged 10 to 19 years who underwent PSF with intraoperative LB between 2020 and 2022 at a single institution. Patients were stratified by BMI percentile (underweight, healthy weight, overweight, and obese). Postoperative opioid consumption was quantified in morphine equivalents per kilogram (MME/kg) and analyzed for the first 24 hours and total inpatient stay. Pain scores, SRS-30 outcomes, and pain catastrophizing were assessed. Multivariable linear regression with backward selection was used to evaluate predictors of opioid use.
RESULTS
A total of 190 patients were included. In the first 24 hours, obese patients consumed less MME/kg ( β =-0.08, P =0.0290), but this association lost significance after backward selection. However, obese patients consumed significantly less total inpatient MME/kg than healthy-weight patients ( β =-0.50, P =0.0001), a difference that remained significant after backward selection. Increasing BMI percentile correlated negatively with total inpatient opioid use (ρ=-0.182, P =0.012). Male sex and higher pain scores were consistent predictors of early postoperative opioid use. There were no differences in pain scores, SRS-30 scores, or pain catastrophizing across BMI groups.
CONCLUSIONS
Contrary to our hypothesis, obesity was associated with significantly lower postoperative opioid use over the total inpatient stay following PSF with LB. These findings suggest a possible opioid-sparing effect of LB in obese pediatric patients, potentially due to altered drug pharmacokinetics. Further prospective studies are needed to investigate the mechanisms underlying this effect.
LEVEL OF EVIDENCE
Level III-retrospective cohort study.