Pain Relief at Iliac Crest Bone Harvest Sites in Spine Surgery Using Bupivacaine

Overview

The use of iliac crest bone graft (ICBG) remains the gold-standard in spinal reconstructive surgery for achieving fusion. Major complications from the harvesting of ICBG are rare, but chronic pain has been reported in 10-39%. Catheters implanted at the time of surgery have been used to provide local anesthetic at the harvest site for 24-48 hours after surgery. This has been shown to decrease chronic pain at 4 years post-operatively. A single application of local anesthetic at surgery has been shown to decrease pain at the harvest site for up to 5 days. No study has demonstrated a benefit to using a single application of local anesthetic at the ICBG site beyond 5 days. In current clinical practice, the use of a local anesthetic at the ICBG site is determined according to surgeon preference. The purpose of this study is to determine if a single application of bupivacaine at the ICBG site, as currently done in some cases, provides any pain relief beyond 5 days such as that demonstrated with longer infusions of local anesthetics.

The use of local anesthetic at the donor site has been investigated to decrease the morbidity of iliac crest bone harvesting. Along with a decrease in early post-operative pain that may be expected a decrease in chronic pain and improved long-term results have also been demonstrated. Local anesthetics may cause such long-term results by dampening the initial chemical response to injury by reducing the release of inflammatory mediators from neutrophils, neutrophil adhesion to the endothelium, and the formation of free oxygen radicals. Most studies have utilized continuous or periodic infusions of anesthetic through a catheter placed at the time of surgery for 24-48 hours postoperatively. The drawbacks to using a catheter include increased infection risk and increased cost if a continuous infusion is used . A single treatment of local anesthetic at the time of surgery is therefore preferable. Only one study has evaluated a single injection of local anesthetic in adult spine patients, demonstrating decreased pain and narcotic usage through 5 post-operative days. No study to date has demonstrated a decrease in intermediate or long-term donor site pain through a single application of anesthetic, as achieved in previous studies utilizing post-operative infusions via a catheter. Participants in the study will be identified in by the attending surgeons on this study who are clinical faculty within the department of orthopaedics and board certified in spine surgery. Randomization will be done by random selection of a sealed envelope by the attending physician at the time of enrollment. Sealed envelopes will contain a paper that assigns the patient to the treatment (bupivacaine at bone harvest site) or placebo (normal saline at bone harvest site) group. Note that all surgical wounds are routinely irrigated with normal saline prior to skin closure. In the control group, 10ml more of normal saline will be used in the ICBG site. In the treatment group, 10ml of bupivacaine 0.5% will be administered directly into the surgical wound, as done in some cases currently. Therefore, there are no new procedures in this protocol outside of what is already being done in practice. The current practice of using versus not using local anesthetic at the iliac crest bone graft site is at the discretion of the attending surgeon. Please note that the randomization in this study has nothing to do with the surgery that is done, and all patients will be treated according to standard of care regardless of this randomization. There are no other differences between treatments in the two study groups. There are no deviations from normal post-operative care received. Patients will not be told whether or not they receive bupivacaine at the iliac crest bone graft site at the time of surgery. The patient will be blinded to their treatment group throughout the study. At the patient's request, they will be informed of their treatment group at the end of the study. The attending surgeon will not be blinded to the treatment group. The PI will not be blinded to the treatment group. Background information about the patient and a pain assessment will be done at the time of enrollment by asking participants to fill out a paper questionnaire. Paper questionnaires to assess the patient's pain level will be given to and collected from patients at discharge from the hospital, the first follow up appointment (approximately 2-4 weeks postoperatively), and at the next follow up appointment (approximately 3 months postoperatively). In addition, patients will be given a paper narcotics log to enter their daily oral narcotic usage between the time of discharge and their first follow up appointment.