The Anterior Cruciate Ligament (ACL) is a band of tissue deep within the knee that connects the thigh bone to the shin bone, providing stability to the joint. An ACL tear is one of the most common and debilitating injuries in sports, often requiring extensive recovery and surgery. Determining which sport has the most ACL injuries is complex because the answer depends on whether one measures the total number of injuries or the rate of injury per athlete exposure. Gender is also a significant factor that dramatically influences the risk profile across comparable sports.
The Sports with the Highest Injury Rate
The most accurate way to compare injury risk is by calculating the rate of injury per 100,000 athlete exposures (AEs), where one AE is one athlete participating in one practice or game. High school girls’ soccer consistently demonstrates one of the highest rates of ACL injury, often reported between 12.2 and 13.3 injuries per 100,000 AEs. This is closely followed by American football for boys (around 11.1 injuries per 100,000 AEs) and girls’ basketball (10.3 to 12.2 per 100,000 AEs).
These sports share common characteristics that elevate the risk, including rapid deceleration, sudden changes in direction, pivoting, and jumping maneuvers. While girls’ soccer and basketball have the highest rates of injury, American football often accounts for the highest total number of ACL injuries annually. This difference is due to the sheer volume of participants in football, meaning that even with a slightly lower rate, the overall count of injuries is higher. The distinction between rate and total number is important for understanding both the individual athlete’s risk and the overall public health burden.
Why the Rate is So High: Mechanism and Gender
The majority of ACL tears occur without direct contact from another player, known as a non-contact mechanism. These injuries typically happen during sudden movements like landing awkwardly from a jump, quickly cutting or pivoting, or rapidly decelerating. The forces generated during these actions, particularly when the knee collapses inward, can overload the ligament. In contrast, contact injuries, which are more common in sports like American football, involve a direct blow to the knee, often from a tackle.
Female athletes are disproportionately affected, experiencing ACL tears at a rate 2 to 8 times higher than their male counterparts in comparable sports. This disparity is attributed to a combination of factors, beginning with biomechanics. Female athletes often exhibit dynamic knee valgus, where the knee collapses inward toward the midline of the body during landing or cutting movements. They also tend to land with straighter knees and less hip flexion, which increases the strain placed directly on the ACL.
Anatomical differences also contribute to the heightened risk profile for female athletes. A wider pelvis results in an increased Q-angle, altering the knee’s alignment. Furthermore, female athletes may have a narrower femoral notch and thinner ACL tissue overall, which makes the ligament more susceptible to tearing.
Hormonal fluctuations throughout the menstrual cycle are another factor. Changes in hormones like estrogen and relaxin may affect the laxity or stiffness of the ligaments, potentially increasing vulnerability.
Targeted Prevention and Recovery
The high prevalence of non-contact injuries has led to the development of targeted interventions focused on modifying movement patterns. Neuromuscular Training (NMT) is the primary strategy used to address biomechanical risk factors. These programs train the nerves and muscles to promote safer movement patterns. NMT typically incorporates exercises focused on strengthening the hamstrings and core, improving balance and proprioception, and practicing plyometrics to enhance landing technique.
Consistent participation in NMT can reduce the risk of non-contact ACL injury in female athletes, with reported reductions ranging from 43.8% to 73.4%. Following an ACL tear, the typical recovery path involves surgical reconstruction, which is performed in over three-quarters of high school cases, and an extensive period of physical therapy. Athletes face a high risk of re-injury upon returning to high-risk sports. Awareness and implementation of evidence-based prevention programs are paramount for athletes in high-risk sports to mitigate the chance of this debilitating injury.