It's true studies show female athletes are four to six times more likely to injure the knee. One factor may be the difference in proprioception between men and women. Joint proprioception is the ability to sense joint position.
Fatigue of the leg or overall body fatigue may affect proprioception. Men seem to be affected by this more than women. This factor may help explain injuries in men. Some other mechanism of injury may be important for women.
Researchers get a better picture of results by studying just men or just women instead of a mixed group. Both kinds of studies are underway.