Classic history and presentation: History may include rapid acceleration and kicking sports such as sprinting, hurdling, soccer, and water skiing.
Prevalence: Up to 30% of acute athletic injuries involve the hamstrings. Professional soccer players injure their hamstrings at a rate of about 20% per season.
- Age – Skeletally mature athletes and "weekend warriors."
- Sex / gender – Male athletes are most commonly affected.
Pathophysiology: Eccentric contraction of hamstrings while in position of maximum stretch leads to a continuum of injury ranging from myofibril disruption to disruption of the extracellular matrix and fascia, resulting in bleeding, retraction, and scar formation.
Grade / classification system: Proximal hamstring injuries are generally descriptive based upon MRI: number of tendons involved, amount of retraction from ischial tuberosity. Cohen et al described an MRI Scoring System for Hamstring Injuries that predicts time missed from competition. If the injury occurs in the muscle, a standard grading scheme of grade 1 (stretched), grade 2 (partial tear < 50% of muscle belly), or grade 3 (complete tear) may be used.