Been doing CF now since January 2016 and since a week now I feel my knees are giving in. Yesterday during an 80kg frontsquat my left knee gave way and had to drop the weight. Felt a knife-like stab in my kneecap…taking things calm now, but hope to get back at it soon. Any advise to avoid this in future. For now doctor advise is to have my knees rest, iow now leg exercises.