“While physicians may prescribe medical devices for unapproved uses, a manufacturer may not distribute medical devices in interstate commerce with the intent that those devices be used for unapproved purposes”
This sentence in an article on whistleblowerfirm website grabbed my attention. So it is possible for doctors to prescribe an FDA approved device to be used by the patient even in an unapproved way but not to use an unapproved device. So it is about selling the device in the market (There may be some rare exemptions for the 510(k) premarket approval). This could be useful in some cases for sure, as long as the device is initially safe to be used (not a Class III devices with a high-risk level) and not for invasive use such as electrical bone simulator.
I found as934 reply interesting as I never heard before about the Humanitarian Device Exemption (HDE) Program.