Been there and have done that. (leg 'appliance') I have no issues with being scanner (it is 'no option' in many parts of the world).
The TSA person actually asked me if I had any places that were painful. Yes, I did and they were not touched.
My leg looked really awful and I was more concerned about not being able eto board my flight if the thing was noticed by airline employees.
If you refuse the scan, your results could vary a great deal.