ABSTRACT
BACKGROUND: Intra-articular narcotics have proven efficacy for providing pain relief following knee arthroscopy. This effect is short-lived. Methadone, with its long serum half-life (thirty-five hours, compared with two hours for morphine) could provide improved and prolonged pain relief. The purpose of the present study was to examine the effects of an intra-articular injection of methadone on postoperative analgesia following arthroscopic anterior cruciate ligament reconstruction. METHODS: Sixty-five skeletally mature patients undergoing primary anterior cruciate ligament reconstruction were randomly assigned to one of three groups, all of which received an intra-articular injection consisting of 9.5 mL of 0.5% bupivacaine with 1:200,000 epinephrine at the completion of the procedure. In addition, the remaining 0.5 mL of the syringe was filled with one of three substances. The study group (twenty-five patients) received 5 mg of methadone, the comparison group (twenty-one patients) received 5 mg of morphine, and the control group (nineteen patients) received 0.5 mL of saline solution. All supplemental pain medications were given on an as-needed basis, recorded, and converted to morphine equivalents. Specific variables that were measured included supplemental analgesia requirements during both the inpatient period and the outpatient period (from the time of discharge to the seventh postoperative day) and pain scores. RESULTS: There was no significant difference in inpatient (p = 0.998) or outpatient (p = 0.887) supplemental analgesic requirements or pain scores between the methadone group (Group 1) and the control group (Group 3). The morphine group (Group 2) required significantly less inpatient (p = 0.014) and outpatient (p = 0.044) supplemental analgesia compared with the control group (Group 3). There were no complications. CONCLUSIONS: The present report represents the first known study of the use of intra-articular methadone and establishes that this analgesic is safe at a single dose of 5 mg. At this dose, however, methadone does not provide improved postoperative analgesia following arthroscopic anterior cruciate ligament reconstruction. In contrast, intra-articular morphine does appear to be effective for decreasing postoperative pain.
