The cause of an anterior cruciate ligament (ACL) rupture typically involves a sudden movement that puts the knee in an unnatural position, such as sudden stopping and twisting of the body or a hard impact on the knee during sports. An ACL tear can also occur due to overuse or wear and tear over time.

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Injury to the anterior cruciate ligament (ACL) is one of the most common injuries in amateur and elite sports. Men between the ages of 15 and 25 are at the highest risk. Most injuries occur in sports without physical contact (approximately 70%).

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Most often, an injury to the anterior cruciate ligament occurs during sudden stopping, rapid changes of direction, or rotational movements with good traction or during landing after a jump. This leads to valgus stress on the knee joint with simultaneous external rotation of the lower leg. This rotational and shearing force causes overstretching of the anterior cruciate ligament. The body posture is usually upright with slightly bent hip and knee joints. The body's center is behind the knee joint, resulting in an unfavorable lever arm. The quadriceps muscle contraction in a bent knee joint increases the load on the ACL, while the hamstrings act protectively by stabilizing the tibia. While non-contact sports more often lead to ACL ruptures, contact sports are more likely to cause injuries to the cartilage and medial collateral ligament (grade III).

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The reason for the difference in injury frequency between genders is not fully understood. It is believed to be due to lower ligament strength and muscle power in female athletes. The more frequent occurrence of genu valgum, increased femoral anteversion, and higher Q-angle in the female population also appear to be predisposing factors. Attempts have also been made to include the intercondylar notch in this consideration. A narrower notch in women is thought to lead to a higher rupture rate compared to men who have a wider notch. Impingement of the cruciate ligament and its smaller diameter are believed to contribute to an increased rate of cruciate ligament ruptures.

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Diagnosis

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In addition to history-taking and identifying the cause of the injury, clinical examination and imaging are of great importance. A thorough clinical examination can distinguish between a stable and an unstable knee joint. Magnetic resonance imaging (MRI) can effectively visualize the cruciate ligaments and other knee structures to further evaluate injuries.

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Treatment

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After surgery, it is important to initiate postoperative rehabilitation from the first day. In patients under 20 years of age, the probability of a rerupture can be as high as 40% if they continue to participate in the sport that caused the injury. Return-to-sport tests are used to protect patients from returning to sports too early and potentially suffering another injury.