Well, at my house there's a place where the step down from the driveway to the ground on one side is a 2 foot drop or so... I stepped down there one day after it had rained a couple-three days, and my foot slipped, and I wound up with all my weight coming down with my leg bent up under me...
The diagnosis was a sprain, possible slight tear, of the lateral collateral ligament, a pulled or possibly slightly torn quad muscle just above the knee, and a slight pull of the calf muscle right where it attaches behind the knee...
The doctors tried to talk me into taking an MRI to find out for sure if we were looking at a tear, but I told them they'd need to bring about six men along if they planned on getting me into that flippin' tube... I told them I'd limp around on my cane for a week or two, and see if I was still suffering...
Well, at this point the knee isn't near as sore, but more important, it isn't near as STIFF as it was in the day or two after the accident... that was a rough time, when I couldn't sleep for the discomfort, even with the pain meds... but honestly, I do believe I'm on the mend...
Curiously, I think one of the things that kep the injury from being worse was the number of times I hyperextended that left knee during my younger, basketball playing days... I believe that that series of injuries kinda stretched the LCL and ACL ligaments a bit... this rendered them a bit more flexible than most people's ligaments would be...
Thanks for asking, but please don't worry, this too shall pass... and with each passing day, it looks more and more like I'll be able to avoid the knife again...