I also have a prosthetic knee and never have I been offered private screening. They wand me in front of everyone going by and I have to sit and show the bottoms of my feet. And during all this screening, what is happening to the belongings I have passed through security? No one offers to retrieve your items and place them near you. If you're not travelling with someone, then your stuff will probably be gone and TSA cannot be held accountable. This is the reason I hate flying. TSA does discriminate against innocent people who now have to live with metal in their bodies.