The effect of ketorolac on posterior minimally invasive transforaminal lumbar interbody fusion: an interim analysis from a randomized, double-blinded, placebo-controlled trial

Abstract

Background context: Postoperative pain control following posterior lumbar fusion continues to be challenging and often requires high doses of opioids for pain relief. The use of ketorolac in spinal fusion is limited due to the risk of pseudarthrosis. However, recent literature suggests it may not affect fusion rates with short-term use and low doses.

Purpose: We sought to demonstrate noninferiority regarding fusion rates in patients who received ketorolac after undergoing minimally invasive (MIS) posterior lumbar interbody fusion. Additionally, we sought to demonstrate ketorolac's opioid-sparing effect on analgesia in the immediate postoperative period.

Study design/setting: This is a prospective, randomized, double-blinded, placebo-controlled trial. We are reporting our interim analysis.

Patient sample: Adults with degenerative spinal conditions eligible to undergo a one to three-level MIS transforaminal lumbar interbody fusion (TLIF).

Outcome measures: Six-month and 1-year radiographic fusion as determined by Suk criteria, postoperative opioid consumption as measured by intravenous milligram morphine equivalent, length of stay, and drug-related complications. Self-reported and functional measures include validated visual analog scale, short-form 12, and Oswestry Disability Index.

Methods: A double-blinded, randomized placebo-controlled, noninferiority trial of patients undergoing 1- to 3-level MIS TLIF was performed with bone morphogenetic protein (BMP). Patients were randomized to receive a 48-hour scheduled treatment of either intravenous ketorolac (15 mg every 6 hours) or saline in addition to a standardized pain regimen. The primary outcome was fusion. Secondary outcomes included 48-hour and total postoperative opioid use demonstrated as milligram morphine equivalence, pain scores, length of stay (LOS), and quality-of-life outcomes. Univariate analyses were performed. The present study provides results from a planned interim analysis.

Results: Two hundred and forty-six patients were analyzed per protocol. Patient characteristics were comparable between the groups. There was no significant difference in 1-year fusion rates between the two treatments (p=.53). The difference in proportion of solid fusion between the ketorolac and placebo groups did not reach inferiority (p=.072, 95% confidence interval, -.07 to .21). There was a significant reduction in total/48-hour mean opioid consumption (p<.001) and LOS (p=.001) for the ketorolac group while demonstrating equivalent mean pain scores in 48 hours postoperative (p=.20). There was no significant difference in rates of perioperative complications.

Conclusions: Short-term use of low-dose ketorolac in patients who have undergone MIS TLIF with BMP demonstrated noninferior fusion rates. Ketorolac safely demonstrated a significant reduction in postoperative opioid use and LOS while maintaining equivalent postoperative pain control.

Keywords: Ketorolac; Lumbar fusion; Minimally invasive surgery; NSAIDs; Opioids; Patient-reported outcomes; Pseudarthrosis; Transforaminal lumbar interbody fusion.