Pump Up the Pain Relief

Abstract & Commentary

Synopsis: Continuous bupivacaine infiltration using a portable outpatient pump resulted in less pain and less narcotic usage following ACL reconstruction.

Source: Hoenecke HR Jr, et al. The efficacy of continuous bupivacaine infiltration following anterior cruciate ligament reconstruction. Arthroscopy. 2002;18(8):854-858.

It is generally considered standard of care now to perform ACL reconstructions on an outpatient basis. Pain control is the limiting factor in the success of this. Autograft patellar tendon reconstruction is a painful procedure, especially regarding donor site morbidity. Various methods have been used to improve pain relief for the patient and optimize this as an outpatient experience, including femoral nerve blocks, intra-articular anesthetics, and various pain medication cocktails. Hoenecke and colleagues provide the first prospective, randomized, placebo-controlled, double-blind study that explores the efficacy of disposable pumps to administer continuous local anesthetic.

The study design involved 26 patients randomly assigned to either receive saline as a placebo or bupivacaine for 48 hours after ACL reconstruction. At the conclusion of the case, a small catheter was tunneled under the skin and placed into the patellar tendon defect and partially into the knee joint. Both groups received an initial bolus of 35 mL of 0.25% bupivacaine and 5 mg of Morphine intra-articularly at the conclusion of surgery. The experimental group then received an infusion of 2 mL per hour of bupivacaine while the control group received saline. Patients and evaluators were blinded.

The study group showed a statistically significant difference in visual analogue pain scores as well as pain relief scores at all time points. They also consumed 37% less narcotics than the placebo group. All other surgical and demographic variables were comparable between groups. Hoenecke et al conclude that the technique to provide continuous local anesthetic with the disposable pump on an outpatient basis was effective and safe.

Comment by David R. Diduch, MS, MD

Although we have numerous ACL studies regarding surgical variables, this is a welcome addition to the literature as it addresses the important issue of pain control in the perioperative period and is carefully designed and executed. A prospective, randomized, double-blind, placebo-controlled study offers little room for criticism. Their findings were convincing and consistent at each time point. Basically, the study group showed less pain, improved pain relief, and less narcotic use, all desirable outcomes for ACL surgery on an outpatient basis. Furthermore, they found that the system was safe on an outpatient basis and that either the patient or the physical therapist could effectively remove the catheter without any problems at the end of the 48-hour infusion period. The pump is designed such that the rate of anesthetic administration is controlled and foolproof. It would be interesting to determine if higher rates of administration above 2 mL per hour would be even more effective. Their total bupivacaine dose, including the 35 mL bolus at the conclusion of the case, was just 182.5 mg, still well below the published recommended limit of 400 mg over 24 hours.

Other strengths of the study include that they used a dose equivalency system to convert all narcotics to a single scale, both p.o. and IV, for more direct comparisons. They also measured recovery room time and noted that the study group left more than one-half hour sooner on average than the placebo group. Certainly on all fronts the addition of this pump system improved patient outcomes of having outpatient ACL surgery. The only negative to the approach remains cost for the disposable pump system. This is certainly something that surgeons and patients have to weigh in decision making. It may also be something that is variable according to insurance reimbursement and geographic region. This type of paper also helps provide insurance companies with supportive evidence to reimburse this therapy in the interests of patient pain control and overall cost savings by keeping the patients out of the hospital.

Dr. Diduch, Associate Professor, Department of Orthopaedic Surgery, University of Virginia School of Medicine, Charlottesville, VA, is Editor of Sports Medicine Reports.