Adult thigh muscle injuries—from diagnosis to treatment: what the radiologist should know

Muscle injuries are one of the major problems facing elite athletes, representing a significant source of time lost from competition, with substantial consequences for teams and athletes. There are considerable pressures for a rapid return, but players who return to competition too soon have an increased risk of recurrent muscle injuries, which are associated with longer lay-offs. Imaging plays a key role in achieving the correct diagnosis, and magnetic resonance imaging (MRI) has emerged as the method of choice for skeletal muscle imaging. Several authors have reported prognostic MRI features, but it is difficult to predict the exact length of time to return to full training afterwards due to considerable discrepancy and overlap between different injuries. Therefore, development of a universally applicable classification and grading system is challenging. This paper aims to: (a) review the contemporary role of imaging in the setting of muscle injuries, with special focus on thigh muscles; (b) list the most accepted terminology used to describe muscle injuries; (c) review the most recent classification and grading systems reported in the literature; and (d) illustrate muscular MRI findings and examine their prognostic value.