Table 1

Classification according to Peetrons8

Grade 0Lack of any lesion using MRI* or US, despite clinical diagnosis of posterior thigh muscle injury.
Grade 1Minimal elongations with less than 5% of the muscle involved.
Grade 2Partial muscle ruptures. They correspond to lesions involving from 5% to 50% of the muscle volume or cross-sectional diameter.
Grade 3Complete muscle tears with complete retraction. Usually, these lesions are clinically evident because the muscle belly forms a real mass and because a gap can be palpated between the retracted ends of the muscle.
  • * This classification is originally described for ultrasound; Davis26 described the same classification for MRI.

  • US, ultrasound.