CAM walker/Moonboot/Air walker

Recently I seem to be getting referrals ++ to physio for the prescription of CAM walkers/moonboots/airwalkers. It seems it is currently in vogue for GP's (or is it just the GP's in my area??) to refer for them for a range of conditions, not all of which are appropriate (in my opinion!)... ankle sprains, phalanx # or poor compliance with casting...

I wonder if anyone has access or could direct me to some good quality studies on the applications for CAM walkers?
Cheers.