Abstract: A device for the detection of slippage of magnetic coupling between an implanted medical device having a magnet and an externally applied magnetic field includes at least one external magnet configured to apply the externally applied magnetic field, an induction coil disposed external to the subject and between the at least one external magnet and the implanted medical device, and a detection circuit operatively coupled to the induction coil and configured to detect slippage between the rotational orientation of the magnet of the implanted device and the externally applied magnetic field based at least in part on the varying frequency components of the voltage waveform across the induction coil.

Abstract: A rotational correction system includes an implant having first and second sections, the implant having a rotatable permanent magnet disposed in a housing of the first section, the rotatable permanent magnet mechanically connected to a nut operatively coupled to the second section. A keyed portion is interposed between the nut and one or more non-linear grooves disposed on an inner surface of the housing. An external adjustment device having at least one rotatable magnet configured to rotate the rotatable permanent magnet of the implant is part of the system. Rotation of the rotatable permanent magnet of the implant in a first direction effectuates a clockwise change in the rotational orientation of the first section relative to the second section and rotation of the rotatable permanent magnet of the implant in a second direction effectuates a counter-clockwise change in the rotational orientation of the first section relative to the second section.

Abstract: A method for treating a fracture with a variable length nail is provided. The nail is configured for at least 5 mm of axial length change in each direction. An incision is made in proximity to a fractured bone and canal is cleared through the center of the bone. The variable length nail is inserted into the canal and a distraction shaft and a housing are secured to separate portions of the fractured bone. The incision is allowed or caused to close. An external adjustment device with at least one rotatable magnet is placed in proximity to the patient's skin. The external adjustment device is operated so that a magnetic field of the at least one rotatable magnet of the external adjustment device causes the rotatable permanent magnet of the variable length nail to rotate, causing either extension or retraction of the distraction shaft relative to the housing.