Purpose: Harvesting of iliac crest graft for spinal fusions is associated with a number of patients reporting residual pain at the harvest site. Various interventions have been proposed to minimize the pain associated with this. The purpose of this study was to evaluate the efficacy of intra-operative infiltration of morphine into the iliac crest harvest site for reduction of postoperative pain.

Method: A double-blinded, placebo controlled study was performed comparing intraoperative infiltration of 5mg of morphine (treatment) vs. saline (placebo) into the iliac crest harvest site for patients undergoing elective spinal surgery. Patients with myelopathy, excessive preoperative opiod use (60mg equivalent morphine/day or more), or multilevel (greater than 3 levels) spinal surgery were excluded. Postoperative administration of morphine (recovery room and PCA) was standardized. Numerical pain scores specific for the iliac crest site were determined in the immediate postoperative period and at 3, 6 and 12 months. Ad hoc power analysis demonstrated that 36 patients would be able to detect a clinically significant difference of 2.4 points on a 10 point numerical pain scale (alpha = 0.05, power = 80%).

Results: 37 patients were randomized and evaluated with a minimum of one year follow-up. The groups were similar in baseline age, gender and comorbidity. There was no significant difference between groups in total use of postoperative morphine during the first 24 hours (treatment: 320mg +/− 268mg, placebo: 293mg +/− 182mg, p = 0.73). There was no significant difference in iliac crest activity pain scores at 1 year (treatment: 1.7 +/− 3.0, placebo: 1.1 +/− 2.4, p = 0.48) or at any of the earlier time points. The proportion of patients with moderate to severe iliac crest pain at one year follow-up was the same between both groups.

Conclusion: This study has demonstrated that there are no additional benefits for the use of intra-operative infiltration of morphine into the iliac crest harvest site during spinal fusions.