knee brace for knee injury prevention

[flybars]

I've read all the post's on knee braces and how they help the rider with injured knee's. I'm just curious if it would be smart for me to start wearing brace's to prevent a knee injury?
I have tweaked both knee's pretty good since I started riding offroad six years ago. And I think they are more prone now to injury. I'm 61 years old and really hope/plan to ride for many years to come.
I have read somewhere that it is possible to break your femur while wearing a knee brace.
I would really like to hear your thought's on this important subject. Thanks in advance.