Introduction:
Most commonly injured muscle group
Typically occurs at musculotendinous junction
Anatomy: click here
Avulsion:
Usually tendon avulsion, proximal far more common than distal, most commonly involves conjoint tendon associated with complete or incomplete semimembranosus tear.
Distal avulsion are usually seen in water skiers and football players, semitendinosus being the commonest
Radiograph: for avulsion fracture; usually not seen in adults, but associated in adolescents
US: superior to MR in distal injuries
MR: superior to US in proximal and muscle injuries. Tendon retraction and tendon edge are better seen
Strain:
Grading
Sites:
1. Musculotendinous junction (MTJ); most common site; proximal MTJ more often than distal MTJ. Semitendinosus and semimembranosus are failry equally affected
2, Epimysial regions: commenest at fusion site of long and short heads of biceps, followed by posterior boundary of biceps proximal to formation of distal tendon
3. Belly injuries: associated with hematoma and may track down along the sciatic nerve
Atrophy and fatty replacement:
Long term complication of untreated injuries
Scarring:
Long term complication
Low signal on all pulse sequences
Treatment and prognosis:
Good if treated early
References:
Koulouris G et al. Hamstring Muscle Complex: An Imaging Review. RadioGraphics 2005;25:571-586
Journal watch: Click Here
