Risk and Prognosis of Hamstring Injuries in the National Football League: A 12-Year Review.

Background: Hamstring injuries can have a significant burden on a professional football player's career and performance. One in 4 players will suffer a lower extremity strain in their career, with the hamstring being the most common. These injuries are often fraught with extended periods of recovery and reinjury rates varying between 16% and 38%.

Purpose: To determine the progression and duration of hamstring injury as well as risk factors and probability of reinjury in the National Football League (NFL).

Study design: Descriptive epidemiology study.

Methods: Data were extracted from the official publicly accessible NFL database of injuries. NFL players suffering a hamstring injury during the study period of 2008-2020 were identified. Injuries were reported weekly as mandated by the NFL. Players were deemed cleared from injury when no longer listed in the injury report (IR). Reinjury was defined as any subsequent hamstring injury after a player's initial injury. The duration of injury and factors associated with injury were analyzed. Secondary objectives included team-specific injury rates and timing of injury.

Results: A total of 2101 hamstring injuries occurred among 1354 players. The mean duration of the IR was 2.4 ± 2.1 weeks. A total of 442 (33%) players suffered subsequent reinjury, 27% of which occurred during the same season. The mean duration on the IR for reinjury was 2.4 ± 1.8 weeks, with no significant difference in duration compared with initial injury (2.4 ± 1.8 vs 2.2 ± 1.7; P = .138). Defensive skill players were most frequently injured (50.4%) followed by offensive skill players (37.7%). Of the 4812 total IR listings, 1806 (38%) did not participate in practice. A total of 1590 (33.5%) had limited participation in practice, and 1353 (28.5%) had full participation in practice. Injury rates among teams varied and ranged from 0.6% (Baltimore Ravens) to 5.7% (Houston Texans), with a median of 3.1% (P < .0001).

Conclusion: Hamstring injuries can have a lasting impact on a player's career with more than a third of players suffering subsequent reinjury. Although suffering a hamstring injury predisposes a player to reinjury, previous injury was not associated with longer recovery times. Rates of injury among organizational teams vary; thus, further research to understand the difference in preventive measures and treatment protocols may be warranted.