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.
Level of Evidence: Therapeutic Level I. See Instructions
to Authors for a complete description of levels of evidence.