I got into fell running a couple years ago but have never thought about technique. I've always just run up and downhill the best way I could as fast as I could (depending on my nerve). Last year I was training hard and a previous knee injury started playing up so I had to lay off and have physio. I've been increasing my training again ready for the three peaks and whilst in the lakes this weekend, my knee started to twinge on the descents. However, I discovered that if I lean back, pull my stomach right in, tuck my bum under and kind of flick my feet out making sure my knees don't go past my ankles, I load my quads more and stress my knees less and I saved myself further pain (except the burning quads but I reckon I can strengthen them with exercise).
Is this a recognised technique? I suspect it must look a bit odd...kind of like cossack dancing! I know it probably is a case of working out what's right for you but I'd be really interested to hear more experienced fell runners recommendations/observations plus advice for saving knees!