Evaluation of postoperative bupivacaine infusion for pain management after anterior cruciate ligament reconstruction

Abstract

Purpose: Postoperative pain control has received increasing attention by health care providers in the new millennium. In fact, pain was called the "sixth vital sign" by the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) in 2001. The continued challenge of effective, safe analgesia in the outpatient setting has promoted the use of various devices designed to deliver local anesthetic directly to the surgical site. We endeavored to evaluate the efficacy of one such device currently in use.

Type of study: Prospective, randomized, placebo-controlled, double-blinded study.

Methods: In this study, 49 consecutive patients were prospectively enrolled and randomly assigned to 1 of 3 groups after anterior cruciate ligament (ACL) reconstruction. Patients and investigators were blinded to group assignment. Group 1 (control group) received no catheter. Group 2 (placebo group) received an infusion catheter filled with saline. Group 3 (experimental group) received the same catheter filled with 0.25% bupivacaine solution. All patients received an ipsilateral femoral nerve block with 30 mL 0.25% bupivacaine and 20 mL 0.25% bupivacaine intra-articular injection. Patients recorded narcotic consumption and pain levels on visual analogue scales twice a day for 4 days after surgery. The catheters were removed on day 4 and physical therapy performance was recorded. The patients were then asked to continue to record pain ratings and medication consumption for an additional 4 days after catheter removal. All patients underwent bone-patellar tendon-bone ACL reconstruction by the senior author (P.D.F.). Seven patients were excluded from the study for ineffective femoral nerve block or catheter disconnection or occlusion. Narcotic consumption and the maximum, minimum, and median pain ratings were analyzed by analysis of variance.

Results: Median pain ratings show lower pain levels (P <.03) for both catheter groups versus the control group. No significant differences were found between the catheter groups for the median pain ratings, but lower maximum pain ratings were seen in the bupivacaine group compared with both placebo and no-catheter control subjects. Postoperative narcotic consumption was also lower in both catheter groups versus control subjects (P <.03). Physical therapy data revealed no difference in range of motion on postoperative day 4. More patients were able to perform straight leg raises during the first therapy session in both the saline placebo catheter group (70%) and bupivacaine group (72%) compared with the control group (50%).

Conclusions: The data suggest some element of placebo benefit at median pain ratings but a protective effect of the bupivacaine at maximum pain levels.