Maybe in the last thirty years,
the number of people that have been practicing sports has increased in number and in frequency of the activities,
including sports like walking,
running,
swimming,
and of course,
playing soccer,
the most important sport in Brazil.
If the number of practioners have increased,
the number of sports-related injuries went in the same direction,
including all tissues,
like bones,
tendons,
or muscles,
for example.
Every week,
we have scanned an increasingly number of people submitted to Magnetic Resonance Imaging (MRI) reporting symptons related to sports activities,
and we observed lesions of all types described in current radiology articles.
Because of this frequency and the importance of these findings,
we decided to perform this retrospective and observational study,
and have reviewed MRI images of patients that concerned about symptons related to sports activities.
These examinations were made between june 2013 and november 2013,
and we selected the most significant cases of muscles strains.
Athletic muscle injuries present a heterogeneous group of muscle disorders which have been difficult to define and categorise,
because of their different sizes and shapes and the complex functional and anatomical organisation.
Muscles that are frequently involved in injuries are often bi-articular or are those with a more complex architecture,
undergo eccentric contraction and contain primarily fast-twitch type 2 muscle fibres.
The most commom classification system used to categorise muscle injury (strain) was devised by O'Donoghue.
This system is based on the classification of the injury severity related to the amount of tissue damage and associated functional loss.
It categorises muscle injuries into three grades,
ranging from grade 1 with no appreciable tissue tear,
grade 2 with tissue damage and reduced strength of the musculotendinous unit and grade 3 with complete tear of musculotendinous unit and complete loss of function.
The currently most widely used classification is an MRI-based graduation based on the clasification of O'Donoghue defining four grades: grade 0 with no pathological findings,
grade 1 only with a muscle oedema,
grade 2 as partial muscle tear and grade 3 with a complete muscle tear.