Abstract
Acute athletic hamstring muscle strain injuries are common and a cause of significant
time off sport. An understanding of the anatomy of the hamstring muscle-tendon units
is a prerequisite for interpreting the spectrum of structural abnormalities on imaging.
The site of injury may range from proximal tendon, proximal myotendinous junction,
with or without tendon injury, muscle, myofascial junction, distal myotendinous junction
to distal tendon. Imaging findings in muscle injury range from intrafascicular and
interfascicular muscle edema, blurring of fascicular margins, distortion of pennation
angle, localized muscle fascicle discontinuity through to more extensive multi-fascicular
discontinuity. Imaging findings in tendon injury include tendon edema, redundancy,
zipper-like morphology, and partial-complete tendon discontinuity. Imaging findings
in fascial injury include poor definition of fascial margins with perifascial edema
through to a fascial defect. Published grading systems are presented, and their so
far limited utility in predicting return to play is reviewed.
Keywords
hamstring - muscle injury - strain - MRI - ultrasound
