The group of athletes that suffers the highest number of catastrophic knee injuries?
Is this note about cheer leaders and knee injuries serious? How do they measure it, in terms of raw number of knee injuries or as a percentage of people involved, or something else?
Serious as a blown knee.
It's measured by comparing the number of serious injuries relative to the number of participants - that's the only legitimate way to measure the frequency of sports injuries, because so many more people play some sports than others.
It has to do with the angle of a woman's legs relative to the ground - because women tend to have wider hips, that means that the legs are angled slightly inward (and with a very minor rotation) as you go from hip to knee. This angling creats unequal stresses on the ligaments from one side of the knee the other. If, say, an MCL is stressed more on the right side than the left, it's likely that it will rip from right to left, resulting in failure of the joint.