Anatomic Risk Factors for Initial and Secondary Noncontact Anterior Cruciate Ligament Injury: A Prospective Cohort Study in 880 Female Elite Handball and Soccer Players.

BACKGROUND

Anterior cruciate ligament (ACL) injury is one of the most severe injuries for athletes. It is important to identify risk factors because a better understanding of injury causation can help inform athletes about risk and increase their understanding of and motivation for injury prevention.

PURPOSE

To investigate the relationship between anatomic factors and risk for future noncontact ACL injuries.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

A total of 870, excluding 9 players with a new contact ACL injury and a player with a new noncontact ACL injury just before the testing, female elite handball and soccer players-86 of whom had a history of ACL injury-underwent measurements of anthropometrics, alignment, joint laxity, and mobility, including leg length, knee alignment, knee anteroposterior laxity, generalized joint hypermobility, genu recurvatum, and hip anteversion. All ACL injuries among the tested players were recorded prospectively. Welch tests and chi-square tests were used for comparison between the groups (new injury group, which sustained a new ACL injury in the follow-up period, and no new injury group).

RESULTS

An overall 64 new noncontact ACL injuries were registered. No differences were found between athletes with and without a new ACL injury among most of the measured variables. However, static knee valgus was significantly higher in the new injury group than in the no new injury group among all players (mean difference [MD], 0.9°; = .007), and this tendency was greater in players with a previous ACL injury (MD, 2.1°; = .002). Players with secondary injury also had a higher degree of knee hyperextension when compared with those previously injured who did not have a secondary injury (MD, 1.6°; = .007).

CONCLUSION

The anatomic factors that we investigated had a weak or no association with risk for an index noncontact ACL injury. Increased static knee valgus was associated with an increased risk for noncontact ACL injury, in particular for secondary injury. Furthermore, hyperextension of the knee was a risk factor for secondary ACL injury.