Good question. Lame answer.

Instead of actually investigating what happens time and time again to the disabled at airports, a newspaper portends to answer a letter by quoting the TSA policies:

Q: Would you please answer a question or find the answer for those of us who have lost a body part in a battle with breast cancer? What should we expect when we walk through the scanners (at the airport)? If the scanners are any good, they will certainly spot a breast prosthesis, then what? Will the Transportation Security Administration employee reviewing the scan be able to recognize the prosthesis and pass it as benign? Will we have to go through a further security check like a pat down?
— Sandra, Muscatine

A: From Jim Fotenos, TSA spokesman: “TSA respects the privacy of all passengers. They have been trained to safely and respectfully screen all passengers, including those with medical devices.
“TSA has created an optional communication card that helps travelers discreetly inform TSA officers about any disability, medical condition or medical device that could affect security screening. Travelers can write their information on the wallet-sized card and hand it to the security officer. While these cards do not exempt anyone from security screening, they allow passengers to communicate information about their medical conditions to the officers discreetly.

“TSA recommends passengers advise our officers of the medical device; passengers will not be required to expose these devices for inspection. Security officers should not ask you to remove medical devices during the screening process and you should be offered private screening by a same-gender officer if additional screening is required to complete the inspection process.”