Muscle strains and other musculoskeletal disorders (MSDs) are a leading cause of work absenteeism.
Muscle pain,
spasm, swelling, and
inflammation are symptomatic of strains. The precise relationship between
musculoskeletal pain and
spasm is not well understood. The dictum that
pain induces
spasm, which causes more
pain, is not substantiated by critical analysis. The painful muscle may not show EMG activity, and when there is, the timing and intensity often do not correlate with the
pain. Clinical and physiologic studies show that
pain tends to inhibit rather than facilitate reflex contractile activity. The decision to treat and choice of
therapy are largely dictated by the duration, severity of symptoms, and degree of dysfunction. Trigger point
injections are sometimes used with excellent results in the treatment of
muscle spasm in
myofacial pain and
low-back pain.
NSAIDs are used with much greater frequency than oral
skeletal muscle relaxants (SMRs) or
opioids in the treatment of acute MSDs. Unfortunately, remarkably little sound science guides the choice of
drug for the treatment of acute, uncomplicated MSDs, and the evaluation of efficacy of one agent over another is complicated by numerous factors. Only a limited number of high-quality, randomized, controlled trials (RCTs) provide evidence of the effectiveness of
NSAIDs or SMRs in the treatment of acute, uncomplicated MSDs. The quality of design, execution, and reporting of trials for the treatment of MSDs needs to be improved. The combination of an SMR and an
NSAID or
COX-2 inhibitor or the combination of SMR and
tramadol/
acetaminophen is superior to single agents alone.