Factors Associated With the Mechanism of ACL Tears in the National Football League: A Video-Based Analysis.

BACKGROUND

The factors associated with anterior cruciate ligament (ACL) injury mechanism in professional American football players are not well-understood.

HYPOTHESIS

It was hypothesized that football-related and player-specific factors, such as position and body mass index (BMI), are associated with ACL injury mechanism in these athletes.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

Videos of ACL tears occurring in National Football League (NFL) games over 6 consecutive seasons from 2014 to 2019 were reviewed by 2 orthopaedic surgeons who specialize in sports medicine. For each injury, the role of contact ( [contact to the injured knee/lower extremity], [contact not involving the injured knee/lower extremity], or ) as well as playing situation and lower extremity position were recorded. Additional player characteristics, timing of injury, and surface information were obtained from NFL game-day and injury database statistics.

RESULTS

Of the 140 ACL tears, a minority occurred via direct contact to the injured lower extremity (30%), although this varied by position. Just over two-thirds (70%) of ACL tears in offensive linemen occurred via direct contact to the injured lower extremity, while wide receivers had no direct contact ACL tears. Elevated BMI was associated with a greater likelihood of ACL tears occurring via direct contact (53% in players with BMI ≥35 kg/m vs 24% in players with BMI <35 kg/m; = <.01). Rookies had the lowest percentage of direct contact ACL tears (18%; = .22). ACL tears that occurred during the middle 8 weeks of the regular season resulted more often from direct contact (38%; = .06). ACL tears that occurred in the third quarter were the most likely to occur via direct contact (44%), while those that occurred in the fourth quarter were the least likely to occur via direct contact (13%; < .01).

CONCLUSION

Although most NFL players sustained ACL tears via a noncontact mechanism (ie, through indirect or no contact), players with an elevated BMI, especially on the offensive line, were more likely to injure their ACL through direct contact. Position-dependent variance in injury mechanism may help guide injury prevention efforts in these athletes.