Patent ID: 7981025

Claim:
A system comprising: an adjustable implant configured for implantation internally within a subject, the adjustable implant comprising a permanent magnet configured for rotation about an axis of rotation, the permanent magnet operatively coupled to a drive transmission configured to alter a dimension of the adjustable implant; an external adjustment device configured for placement on or adjacent to the skin of the subject comprising at least one magnet configured for rotation, the external adjustment device further comprising a motor configured to rotate the at least one magnet and an optical encoder comprising a light source and a light receiver configured to monitor the position of a surface mechanically coupled to the motor, whereby rotation of the at least one magnet of the external adjustment device effectuates rotational movement of the permanent magnet of the adjustable implant and alters the dimension of the adjustable implant; and drive control circuitry configured to receive an input signal from the optical encoder corresponding to the angular position of the at least one magnet and drive the motor of the external adjustment device to achieve a target dimension of the adjustable implant.