Hi Cynthia,
Welcome back to the Disney Parks Moms Panel and thank you for asking us another question!
Although bag checks have been a part of visits to Walt Disney World Resort for several years now, the “secondary screening” involving metal detectors is, as you noted in your question, relatively new. From what I’ve been able to understand, security staff will ask Guests to go through a metal detector at random; not every Guest gets selected for this additional security check.
If you have any questions about the impact of your/your son’s implants on the metal detectors, please direct them to the staff if you are, in fact, selected for secondary screening. I believe a manual search will be possible if you choose not to go through the metal detector.
I hope this helps you plan your visit to Walt Disney World Resort this December! Please don’t hesitate to come back and see us if you have any other questions. If you want more information about any of the security measures I've described above, please feel free to
contact Walt Disney World Resort or to consult the
Walt Disney World Resort Park Rules.
Have a Magical Day,
Lynne