- Wide Receivers – 19.4%
- Linebacker – 15.5%
- Cornerback – 11.7%
- Offensive Line – 10.7%
- Defensive End – 8.7%
Methods: In this study the authors performed a retrospective cohort of National Football League (NFL) players with ACL injuries from 3 consecutive seasons (2013-2016). Of the 156 ACL injuries identified, 77 (49%) occurred during the regular season and playoffs with 79 (51%) occurring in pre-season and training camps. Video analysis was available for 69 injuries which was reviewed to determine the mechanism of injury.
Results: The majority of ACL injuries analyzed occured vai a noncontact mechanism (50 of the 69 or 72.5%). The only exception to this was offensive lineman who had only 20% of their ACL injuries by noncontact mechanism. The most common activity leading to the noncontact injury was pivoting or cutting. The most common position of the limb during the injury was hip adduction/flexion, early knee flexion/abduction and foot abduction/external rotation. There was no association between injury mechanism and time of play or playing surface.
Discussion: The results of this study suggest that the majority of ACL injuries in the NFL occur from noncontact mechanism with the lower extremity exhibiting a dynamic valgus moment at the knee. This lead the authors to suggest that to reduce these types of injuries prevention programs should assess for these movement patterns and develop intervention programs which address.
Aside from these points, there are also some additional key points that came out of this study.
- Lineman are more susceptible to contact ACL injuries. This fact has led a lot of teams at the professional and collegiate level to proactively brace players. Conceptually this might seem like a great idea, but there is very little support that this prevents ACL injuries in contact sports. Additionally, we need to think about what this brace does to gait (how you walk and run) and muscle EMG activity. What we do know is that players wearing two ACL braces walks and runs with an altered gait and EMG activity of the quads and hamstrings is decreased. So what is the answer? We may not have the answer to that yet but we do need to think about how we address this.
- Over 1/2 of ACL injuries are in the preseason. In preseason, a lot of players are coming into preseason and camp in a deconditioned state. Knowing the majority of these injuries are non-contact in orientation, that certain biomechanics add to increased risk of these injuries and that targeted training programs have been shown to decrease risk for these injuries, it seems implementing a post season and preseason movement training program would be beneficial.
- No association between injury rates and time of play. This is basically stating that fatigue did not play a role in the non-contact ACL injuries. There are several authors that suggest that fatigue does play a role and a whole other contingency that states fatigue does not play a role. For those in the fatigue does not play a role camp, they site that the literature simply does not indicate this is the case.