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Muscle tears or strains are common injuries, both in athletes and non-athletes.
Muscle strain is a term that is used variably clinically and in the medical literature. The Munich consensus statement (expert level evidence) states muscle tear is the preferred term denoting "structural injuries of muscle fibers/bundles leading to loss of continuity and contractile properties" 1.
Muscle tears are indirect muscle injury that occurs in eccentric contraction during sprinting or stretching 2. Most commonly these injuries occur at the myotendinous junction (MTJ) but can also be peripheral (i.e. myofascial) 3.
Ultrasound examination may be normal or in low-grade injuries demonstrate focal or diffuse regions of increased echogenicity. Fiber disruption is characterized by well-defined hypoechoic/anechoic regions. Disruption at the myofascial junction or myotendinous junction may be present 1.
MRI features corresponding to clinical grades of injury are 1:
grade 1: T2 high signal with a feathery appearance (usually centered on the MTJ) representing edema +/- thickening and high signal of the intramuscular tendon but without laxity +/- mild perifascial fluid
grade 2: above features with fiber disruption characterized by high T2 signal and local distortion +/- intramuscular tendon high signal with or without thickening, laxity or partial disruption +/- moderate-severe perifascial fluid
grade 3: complete disruption +/- retraction/laxity with local hematoma
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- 3. Mueller-Wohlfahrt H, Haensel L, Mithoefer K et al. Terminology and Classification of Muscle Injuries in Sport: The Munich Consensus Statement. Br J Sports Med. 2013;47(6):342-50. doi:10.1136/bjsports-2012-091448 - Pubmed
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