Intramedullary device for ankle fusion

A method comprising:

• providing an intramedullary device including:
• a housing and a rod configured to be moved relative to the housing, wherein the housing defines a longitudinal axis and includes:
• a first portion having a first diameter and a second portion, wherein the second portion comprises a smooth portion and a second diameter larger than the first diameter, and
• an external thread positioned distally from the second portion at a distal end of the housing, wherein a length of the smooth portion is greater than a length of the external thread;
• a first fixation aperture positioned at least partially on the external thread and being perpendicular to the longitudinal axis;
• a second fixation aperture positioned at least partially on the external thread and being perpendicular to both the longitudinal axis and the first fixation aperture;
• coupling the rod to a tibia bone of a patient;
• coupling the housing to a calcaneus bone of the patient;
• and
• non-invasively retracting the rod relative to the housing, thereby causing compression about an ankle of the patient to cause ankle fusion once the housing is coupled to the calcaneus bone,
• wherein the intramedullary device includes a magnetic drive system which allows the rod to be telescopically retracted relative to the housing,
• wherein the intramedullary device includes an end cap, the end cap being threadingly engageable with threads positioned about an inner surface of the housing,
• wherein the intramedullary device further includes a magnetic maintenance member having two spaced apart tabs and positioned in proximity to the magnetic drive system and configured to eliminate accidental actuation of the intramedullary device, and
• wherein the housing includes a lead screw which turns a nut secured to an inner surface adjacent to a cavity of the rod, the lead screw is mechanically coupled to a cylindrical permanent magnet of the magnetic drive system,
• wherein the rotation of the cylindrical magnet is driven by an external adjustment device, thereby causing rotation of the lead screw,
• wherein the cylindrical permanent magnet is positioned within a magnet housing which includes an axle which couples the magnet housing to a gear assembly,
• wherein the lead screw is configured to freely rotate within the cavity of the rod;
• inserting the first fixation screw through the first fixation aperture and into the calcaneus bone;
• inserting a second fixation screw through the second fixation aperture and into the calcaneus bone such that the inserted first and second fixation screws are perpendicular to each other and to the longitudinal axis.