Hamstring injuries are common in athletic populations and can affect all levels of athletes. From 1989 to 1998, the National Football League surveillance systems identified 1716 hamstring strains amongst all players, with range of 132-210 injuries per year. This accounts for an overall injury rate of 0.77 per 1000 athlete-exposures and a reinjury rate of 16.5%. This is consistent with the rate of muscle strain in high school (12-24%) and collegiate football (18.9-22.2%).
Hamstring injuries can range from musculotendinous strains (partial tears) to avulsion injuries (complete tears). By definition a strain is a partial or complete disruption of the musculotendinous unit. A complete tear or avulsion, in contrast, is a discontinuity of the tendon bone unit (where it tears off the bone). Most hamstring strains do not require surgery and resolve with a variety of treatment including physical therapy and rest. The most important point in evaluating these injuries is to differentiate the complete or partial tears from the muscle strain subgroup, because patients with a complete tear can suffer from more significant disabilities and inability to return to their prior activity levels.