British Athletics muscle injury classification

The British Athletics muscle injury classification (BAMIC/BAC) is a five-point MRI-based system that is based on extent and site. It has been primarily based on hamstring injuries but is used in other muscle injuries. The classification system has been shown to have moderate inter- and intra-rater agreeability . There is ongoing research on the usefulness of this classification system about prognostication for "return to play".

Classification

  • grade 0
  • grade 1 (mild): high STIR signal that is <10% cross-section or longitudinal length <5 cm with <1 cm fiber disruption
  • grade 2 (moderate): high STIR signal that is 10-50% cross-section; longitudinal length 5-15 cm with <5 cm fiber disruption
  • grade 3 (extensive): high STIR signal that is >50% cross-section or longitudinal length >15 cm with >5 cm fiber disruption
  • grade 4: complete tear

Grades 1-3 are subclassified depending on site:

  • a: myofascial (peripheral)
  • b: myotendinous junction / muscular
  • c: tendinous

For grade 4 (complete tears), the distinction is only made between tears involving muscle versus those solely involving the tendon, as follows:

  • grade 4: myofascial, muscular, or myotendinous
  • grade 4c: tendinous