Nina Dobrev is recovering from knee surgery with physical therapy and a CPM machine. Here's how the machine is supposed to help heal—and why it's controversial.

A CPM machine is a “continuous passive motion” device that helps move a joint after an injury. “Thank you to everyone who has been sending kind messages, thoughts, prayers, and good vibes ...

According to Verywell Health, a CPM (or a continuous passive motion machine) is a "motorized device used in physical therapy that gently bends a joint back and forth to aid with recovery following ...