ACL Tears: Causes, Symptoms, and Risk Factors Detailed

The Anterior Cruciate Ligament (ACL) is the most common knee injury, with tears significantly impacting an individual's activity level and quality of life, often presenting a substantial burden in terms of recovery time and financial cost.

The ACL is located in the center of the knee, connecting the femur (thigh bone) to the tibia (shin bone). Its primary role is to prevent the tibia from sliding forward excessively relative to the femur and to provide rotational stability to the knee. Injuries are common in sports requiring sudden changes in direction, jumping, or abrupt stops, such as basketball, soccer, and football.

ACL tears frequently occur during physical activities. Common mechanisms include pivoting movements with the foot planted, sudden deceleration, direct impact to the knee, or improper landings from jumps. Notably, a significant majority, up to 70-80 percent, of ACL tears occur without direct contact with another person.

Approximately 50 percent of non-contact ACL tears are considered potentially preventable through targeted injury prevention programs. These programs can also help reduce the risk of other lower extremity injuries, such as ankle sprains.

ACL injuries are most prevalent among individuals aged 15 to 45. While more injuries occur in sports with higher male participation, women face a significantly higher risk, being 2 to 7 times more likely to tear their ACL than males of the same age. Factors contributing to this disparity in female athletes include a smaller ACL, narrower attachment point, a greater Q-angle (hip-to-knee angle), and often a less optimal quadriceps-to-hamstring strength ratio.