I can relate to this topic, past Saturday was ending my run at Brian head when I navigated to a soft patch of snow. I was doing a toe turn and end up getting caught in the patch, I stumbled and landed face first. Thanks to a helmet no head injuries but my right leg twisted and felt like I broke a bone. Layer their for five mins and quickly got up walking all the way down. I first did some research and thought it was acl or some ligament tore which I'm highly doubting due to my physical interaction with the right leg. I still can't pivot my leg but because my knees are bruised. Which doesn't allow me to lock my leg. Hopefully it ain't bad and ill wait a few days or a week. I natural allow healing stages before seeing a doctor.