It kept bothering me off and on for a couple of weeks, until I finally gave up and limped in to see my doctor. There are many things that can cause knee injuries, but sports are among the most frequent. Surprisingly, women are more susceptible to knee injuries than men.
Men are narrower in the pelvis than women.
This anatomical fact means that a man's legs extend straight down from the hip to the knees, whereas a woman's legs, due to the wider pelvis, extend from the hip to the knee at a more acute angle. This puts more stress on the woman's knee.