Changes in sex hormone levels, specifically elevated levels of estrogen and relaxin in females during the menstrual cycle, have been hypothesized as causing predisposition of ACL ruptures. This is because they may increase joint laxity and extensibility of the soft tissues surrounding the knee joint. Ongoing research has observed a greater occurrence of ACL injuries in females during ovulation and fewer injuries during the follicular and luteal phases of the menstrual cycle.Study results have shown that female collegiate athletes with concentration levels of relaxin that are greater than 6.0 pg/mL are at four times higher risk of an ACL tear than those with lower concentrations.Additionally, female pelvises widen during puberty through the influence of sex hormones. This wider pelvis requires the femur to angle toward the knees. This angle towards the knee is referred to as the Q angle. The average Q angle for men is 14 degrees and the average for women is 17 degrees. Steps can be taken to reduce this Q angle, such as using orthotics. The relatively wider female hip and widened Q angle may lead to an increased likelihood of ACL tears in women. ACL, muscular stiffness, and strength
During puberty, sex hormones also affect the remodeled shape of soft tissues throughout the body. The tissue remodeling results in female ACLs that are smaller and will fail (i.e. tear) at lower loading forces, and differences in ligament and muscular stiffness between men and women. Womens knees are less stiff than mens during muscle activation.
There is evidence that engaging in neuromuscular training (NMT), which focus on hamstring strengthening, balance, and overall stability to reduce risk of injury by enhancing movement patterns during high risk movements. Such programs are beneficial for all athletes, particularly adolescent female athletes.Injury prevention programs (IPPs), are reliable in reducing the risk factors of ACL inquiries, referring to dominance theories. The ligament dominance theory reduced peak knee abduction moment but should be more focused on prioritizing individualized, task-specific exercises focusing on an athletes risk profile. It is more beneficial than a generic program. There is an increase in hip and knee flexion angles, such as plyometrics and jump-landing tasks, which reduces the risk of quadriceps dominance. However, there were no changes found for peak vGRF, which measures for "softer" landings. Unfortunately, there was no conclusive data on how IPPs reduces the risk associated with leg dominance theory. Treatment
Treatment for ACL tears is important to:
Reduce abnormal knee movements and improve knee function
Build trust and confidence to use the knee normally again
Prevent further injury to the knee and reduce the risk of osteoarthritis
Optimise long-term quality of life following the injury

Nonsurgical
Nonsurgical treatment for ACL rupture involves progressive, structured rehabilitation that aims to restore muscle strength, dynamic knee control and psychological confidence. For some, the ACL may heal without surgery during the rehabilitation process (i.e. the torn pieces re-unite to form a functional ligament).The purpose of exercise treatment is to restore the normal functioning of the muscular and balance system around the knee.