Is Angel Wing Painful for Ducks?

[dublinducks]

I have read that angel wing is a purely cosmetic issue for ducks, and that other than rendering them unable to fly it causes no health risk.

Other sources imply that the worse the case is the more likely it is to be painful for the duck.

Is there any evidence to support either of those claims?

 

[sourland]

Evidence? In my experience ducks/geese with angel wing have not seemed to experience pain because of the condition.