External adjustment device
An external adjustment device for non-invasively adjusting an adjustable implant, the external adjustment device including a controller in communication with an actuator associated with the implant and a sensor configured to receive information from or about the implant. The external adjustment device may include a power source and a display. The external adjustment device may include a magnetic element configured to generate a rotating magnetic field; and a driver configured to drive the magnetic element to generate the rotating magnetic field and configured to rotate a permanent magnet of an implant. Upon placing the external adjustment device in proximity to the implant, the magnetic element is configured to magnetically couple with the permanent magnet. The external adjustment device may be configured to non-invasively determine one or more of a magnetic coupling state and a stalled state of the magnetic element and the permanent magnet disposed within the implant.
1 . A method for contactlessly monitoring a response of an adjustable implant having an internal magnet using an external adjustment device having an external magnet comprising:
contactlessly positioning the external adjustment device in proximity to the adjustable implant which has been implanted in a patient to magnetically couple with the internal magnet of the adjustable implant, the external adjustment device including a motor and the external magnet rotatably coupled to the motor;
monitoring a change in angular velocity of the external motor, and using to use the determined change to detect a stalling state of the internal magnet of the adjustable implant.
2 . The method of claim 1 , further comprising determining a coupling state of the external magnet with the internal magnet of the adjustable implant based on a rotational speed of the external magnet.
3 . The method of claim 1 , wherein monitoring a change in angular velocity includes transforming an acceleration array using a fast Fourier transform (FFT).
4 . The method of claim 3 , wherein the determination is made by monitoring a third harmonic of the fast Fourier transform (FFT).
5 . The method of claim 1 , further comprising displaying on a display of the external adjustment device a magnetic coupling state of the external magnet with the internal magnet of the adjustable implant.
6 . The method of claim 1 , further comprising displaying on a display of the external adjustment device an amount of change in a dimension of the adjustable implant.
7 . The method of claim 6 , wherein the display is configured to display a length of the adjustable implant.
8 . The method of claim 1 , further comprising displaying on a display of the external adjustment device a speed of rotation of the external magnet.
9 . The method of claim 1 , further comprising preventing a change in a dimension of an implantable medical device beyond a pre-determined limit.
10 . The method of claim 1 , further comprising displaying on a display of the external adjustment device:
an amount of change in a length of the adjustable implant, and
a speed of rotation of the external magnet.