Wider hips create an angle between the hips and knees that puts stress on knee joints. Women also tend to have a more "knock-kneed" valgus alignment (where knees face inward, towards each other and toes straight) and thinner ACL tissue, meaning it takes less force for the ligament to tear.

After puberty, women tend to develop increased joint laxity, which increases the risk of ligament injuries. Hormonal changes throughout the menstrual cycle may also influence joint flexibility, muscle strength, body temperature, and neuromuscular control.

Female athletes are often more quad-dominant and may have weaker hamstrings. This imbalance can place additional stress on the knee and increase the chance of injury. Women also tend to have less muscle mass surrounding the knee joint, which may reduce the stability and support provided by the surrounding muscles.

When landing from a jump, female athletes are more likely to land with their knees collapsing inward and with less knee bend. In WNBA injury data, 100% of ACL tears occurred with the knee in a valgus position, and 83% were non-contact injuries.