Session XI - Reconstruction
Sun., 10/10/04 Reconstruction, Paper #66, 9:57 am
The Evaluation of Continuous Infusion of Local Anesthetic at Iliac Crest Bone Graft Sites for Postoperative Pain Relief: A Randomized, Double-Blind Study in Orthopaedic Trauma Patients
Purpose: The use of autologous bone graft is the gold standard for reconstruction of bone defects and non unions in trauma and reconstructive orthopaedic surgery. The iliac crest is an easily accessed source for the autologous bone graft. The most common complication is pain at the donor site. Postoperative pain management is an important concern for both patients and surgeons. There have been numerous articles published regarding infusion of local anesthetic into the bone graft harvest site. The technique ranges from local infiltration at the time of surgery, to intermittent infusion using an indwelling catheter, to continuous infiltration. There have been no double blind, randomized, controlled studies to evaluate the efficacy of a continuous bupivacaine infusion in decreasing postoperative pain in the acute postoperative period. The purpose of this study is to determine whether a continuous infusion of 0.5% bupivacaine into the iliac crest harvest site provides pain relief superior to the relief provided by the use of systemic narcotic pain medication alone.
Methods: This study was approved by the Institutional Review Board as a randomized, double blind, prospective study. All patients presenting to the orthopaedic service at two level one trauma centers who were over 18 years of age and undergoing harvesting of iliac crest bone graft as part of the treatment for their extremity injury or reconstruction, were eligible to participate in the study. Patients with hepatic or liver dysfunction, allergies to bupivacaine or morphine were excluded. The patients were randomized to either the treatment arm or the placebo arm. The results of a power analysis indicated that 30 patients were needed in each group to achieve power equal to 0.80 with an alpha of 0.05. Patients underwent harvest of the iliac bone graft utilizing a trap door technique. As the iliac crest site was closed, an epidural catheter connected to a Pain Control Infusion Pump (PCIP) was placed into the wound along the outer table of the iliac crest over the periosteum. An anesthesia provider who was not participating in the care of the patient, and was blinded from the surgeon, loaded the PCIP with either 100cc of 0.5% bupivacaine or 100 cc of 0.9% normal saline. The PCIP infused the treatment medication or placebo into the wound at a rate of 2 ml/hour. All patients participating in the study were placed on a standardized postoperative morphine sulfate PCA. Patients recorded their pain on a scale of 0 to 10, utilizing a standardized visual analogue pain scale for both the donor and recipient sites. Study participants were asked to rate their pain initially in the recovery room then every 8 hours, for the first 48 hours after surgery. Additional pain evaluations were performed at 2 weeks and 6 weeks postoperatively.
Results: Sixty patients were enrolled in the study, two were lost to follow-up. There were 35 males and 23 females. The average age of the patients was 40 years. The anterior iliac crest was utilized in 54 cases and the posterior iliac crest in 4 cases. The average size of the iliac crest osteotomy was 4 cm. The recipient sites included the femur (11), tibia (27), foot and ankle (7), humerus (8), forearm (4), and clavicle (1). There were two infections and 1 hematoma, all occurring at the donor sites. The average in hospital pain score for the donor site was 3.98 for the control group and 4.1 for the treatment group. The average in hospital pain score for the recipient site was 4.93 for the control group and 5.65 for the treatment group. Independent samples t-tests were used to assess whether there were differences in perceived pain relief between the treatment and control groups. Across all data points, except the pain reported at the recipient site at 24 hours, no statistically significant differences in the perception of pain were found between the bupivacaine group and the placebo group. Unexpectedly, the pain reported at the recipient site at 24 hours was significantly higher in the treatment group (x=6.18) than in the control group (x=4.60) (p=0.025). On the average, patients in the treatment group consistently reported more pain than those in the control group.
Conclusion/Significance: The results failed to prove the null hypothesis in this setting. The major strength of the study is its double blind, randomized design. The main weakness in the study is the variation in the size of trap door osteotomy performed, and the degree of variation in recipient sites. Despite the noted strengths and weaknesses, the power was sufficient to demonstrate a statistically significant difference thus avoiding a type II error. The most likely reason that there is no difference between groups in regard to their perceived pain is the use of systemic narcotics in the form of a morphine PCA. While this pain control approach may be beneficial when systemic narcotic administration is not possible, no benefit seems to be gained in the narcotized patient. The results of this study indicate that the continuous infusion of bupivacaine at iliac crest bone graft sites is not an effective pain control measure in the hospitalized patient receiving systemic narcotic medication.