In reply to everyone:
Wearing a knee support - even a simple tubigrip - probably improves proprioception (joint position sense) whilst it is being worn. This is theoretically beneficial. Many people make confident statements about becoming dependent on supports but I'm not aware of any actual evidence regarding the long term positive or negative (deterioration in muscle function) effects of wearing a support in people with OA or other knee problems.
Sounds like Jamie is doing all the right things. Strong, quick-reacting thigh muscles and well-trained balance are essential for anyone with knee OA. I'd be pragmatic about using a support. Finding one that fitted properly would be a good start.
What happened to the promised UKC review of Accapi Nexus products from Craig Smith and others?
http://www.ukclimbing.com/forums/t.php?t=380569&v=1#x5507024
I'm guessing Dr Smith thought the claims surrounding the product were pseudoscience marketing bullsh!t but UKC were too timid to post this. Let's not offend the precious advertisers eh!