Nonsteroidal anti-inflammatory drugs and acetaminophen in the treatment of an acute muscle injury.

BACKGROUND: Nonsteroidal anti-inflammatory drugs are frequently used to treat muscle injuries in athletes. It is not known whether the anti-inflammatory effects of these drugs are important or whether their effectiveness is a result of their central analgesic effect.

HYPOTHESIS: The effects of nonsteroidal anti-inflammatory drugs are no different than the effects of an analgesic (acetaminophen) without anti-inflammatory action in an experimental, acute muscle contusion model.

STUDY DESIGN: Controlled animal study.

METHODS: A standardized, unilateral, nonpenetrating injury was created to the tibialis anterior muscle of 96 adult male mice. Four treatment groups were used: group 1, placebo treatment; group 2, treatment with rofecoxib, a nonsteroidal anti-inflammatory drug with cyclooxygenase-2 selectivity, and treatment after the injury; group 3, rofecoxib treatment starting 24 hours before the injury; and group 4, acetaminophen treatment after the injury. The muscle and the contralateral normal muscle were evaluated at 2, 5, and 7 days after injury by grading of gait, wet weight as a measure of edema, and histologic evaluation.

RESULTS: Group 1 had significantly more gait disturbances at day 2 than all other groups (P < .05). No differences were found at days 5 and 7. Wet weights showed an increase at day 2 in group 1 (P < .01). Again, no differences were found at days 5 and 7. Histology revealed similar inflammatory changes at day 2 in all groups, with regeneration of muscle fibers at days 5 and 7.

CONCLUSIONS: The results indicate that rofecoxib as a nonsteroidal anti-inflammatory drug and acetaminophen as a non-nonsteroidal anti-inflammatory drug analgesic have similar effects. The lack of differences in wet weights and histology suggests that the anti-inflammatory effects of rofecoxib are not an important feature of its action.

CLINICAL RELEVANCE: The routine use of nonsteroidal anti-inflammatory drugs in muscle injuries may need to be critically evaluated because low-cost and low-risk analgesics may be just as effective.