With a direct connection to the bone, click-on appliances like this don't need a prosthesis socket, making it easy to take on and off and avoiding chafing and other skin problems. The "mind control" is enabled by connecting a patient's nerves to the socket, with a special Bluetooth bracelet to receive the signals. It takes three surgeries to make it happen, though, including one to insert the a metal rod into a patient's bone marrow, one to implant the piece that will eventually connect the robot arm, and a third -- performed by a specialized plastic surgeon -- to connect all the nerves that used to control the patient's hand muscles to the upper arm stump. This amplifies the neural signals, which helps when the patient is healed and imagines opening and closing their hand to control the new artificial limb.
The entire process, including surgery and rehab, is strenuous and takes a while to complete. Baggerman lost his arm in a truck accident in 2010, received the next three surgeries between 2013 and 2016 and just started the final phases of the rehabilitation process. No matter how tough it is to train a new robotic arm and hand, though, being able to use it by just thinking about it has got to feel amazing.