A Prospective, Randomized, Double-Blind Study of the Efficacy of Postoperative Continuous Local Anesthetic Infusion at the Iliac Crest Bone Graft Site After Posterior Spinal Arthrodesis

Abstract and Introduction

Study Design: Parallel design, prospective, double-blinded, randomized, controlled trial composed of 2 independent groups treated with a continuous infusion catheter (saline vs. Marcain) placed into the iliac crest bone graft site (ICBG).
Objective: To determine the long-term effects of postoperative continuous local anesthetic agent infusion at the ICBG harvest site in reducing chronic pain, narcotic usage and improving long-term, postoperative function and satisfaction with the surgical procedure.
Summary of Background Data: Harvesting iliac crest bone has been shown to be a source of pain and morbidity. In our initial study, we reported that patients who received local anesthetic at the graft site noted a reduction in acute postoperative pain (VAS) and narcotic usage.
Methods: Twenty-six patients underwent posterior iliac crest bone graft harvesting. Patients were randomly assigned to receive 96 mL (2 mL/h × 48 hours) of either 0.5% Marcain or normal saline delivered via a continuous infusion catheter placed at the ICBG harvest site. Postoperative pain scores, narcotic use/frequency, activity level, and length of stay (LOS) were recorded and reported previously. At a minimum of 4 years after surgery (mean, 4.7 years; range, 4.5-5.4 years), all patients completed a questionnaire documenting their current VAS pain score (iliac crest), frequency of pain (days per month), level of activity, chronic pain at the ICBG site, and overall satisfaction with the procedure.
Results: Nine of 11 patients (82%) in the treatment group and 10 of 14 patients (71%) in the control group were available at final follow-up (1 death occurred in the control group unrelated to the study). The treatment group had a statistically significant decrease in the graft site pain VAS score (1.4 vs. 4.8) and increased satisfaction with the procedure at a minimum of 4 years postprocedure (P < 0.05). Additionally, no patient in the treatment group developed chronic iliac crest dysesthesias (0 of 9) versus 7 of 10 patients (70%) in the control group (P < 0.05).
Conclusion: Continuous infusion of 0.5% Marcain at the ICBG harvest site significantly reduced chronic dysesthesias. Overall satisfaction with the procedure, number of painful days per month, and VAS scores were significantly better in the treatment group at 4 years. No long-term complications were attributed to either the ICBG site or the catheter-infusion system. The use of continuous local anesthetic infusion at the iliac crest may help in alleviating graft-related pain beyond the perioperative phase.

Despite advances in bone-graft substitutes, iliac crest bone graft (ICBG) continues to remain the gold-standard in spinal reconstructive surgery due to its osteoinductive, osteoconductive, and nonimmunogenic properties.^{[1,2,3,4,5,6,7,8,9]} Donor site morbidity has been cited by several authors as a significant postoperative concern for both patient and surgeon.^{[10,11,12,13,14,15,16]} Long-term patient outcomes may be more closely associated with iliac crest site pain rather than the morbidity associated with the spinal reconstruction.^{[5,17,18,19,20]}

Direct application of local anesthetic to wounds can provide analgesia through several mechanisms. There is growing evidence that local anesthetics can inhibit chemical response to injury, a noxious process that may sensitize nociceptive receptors and contribute to chronic pain and hyperalgesia. Studies have observed that local anesthetics reduce the release of inflammatory mediators from neutrophils, reduce neutrophil adhesion to the endothelium, reduction formation of free oxygen radicals, and decrease edema formation potentially reducing the incidence of chronic pain.^[21] One of the inevitable side effects of ICBG harvesting is pain at the donor site with chronic pain being reported in up to 39% of cases.^[6,12,13,22] Various studies have suggested that the use of local anesthetic at the ICBG site reduces postoperative pain and facilitates a quicker return to daily activities.^{[18,20,23,24,25]} However, such studies were either nonrandomized, heterogeneous operative sample groups, and contained various potential confounds and biases.

In our initial study, we reported the immediate postoperative effects of the use of an anesthetic catheter placed intraoperatively at the site of the ICBG harvest.^[26] Patients were blindly and randomly assigned to receive a continuous infusion of saline versus Marcaine. In the acute postoperative period, we found that the use of a local anesthetic decreased narcotic usage by almost 50%. Subjective overall VAS pain scores and iliac crest VAS pain scores were significantly diminished at the time of discharge when compared with preoperative values. Additionally, the catheter resulted in no complications and appeared to be cost neutral.

In this study, we compare the long-term functional outcomes and subjective satisfaction in patients receiving anesthetic infusion or saline control infusion at the ICBG harvest site at a minimum of 4-year follow-up. The current study is prospective and blinded to the treating physician as well as to the data collector and statistician. To our knowledge, there is no reported study in the literature evaluating the long-term benefit of local anesthetic at the ICBG site.

Spine. 2007;32(25):2790-2796. © 2007  Lippincott Williams & Wilkins

The device(s)/drug(s) is/are FDA-approved or approved by corresponding national agency for this indication.

Cite this: A Prospective, Randomized, Double-Blind Study of the Efficacy of Postoperative Continuous Local Anesthetic Infusion at the Iliac Crest Bone Graft Site After Posterior Spinal Arthrodesis - Medscape - Dec 01, 2007.