System and method for altering rotational alignment of bone sections
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.
1. A rotational implant device, comprising:
an implant including
a rod configured to be secured to a first section of a long bone of a subject;
a housing configured to be secured to a second section of the long bone of the subject;
a rotatable permanent magnet disposed in the housing and secured between a thrust bearing and a radial ball bearing;
a lead screw configured to be rotated by the rotatable permanent magnet; and
a nut mechanically connected to the lead screw, the nut configured to interface with the rod by one or more cooperating teeth on each of the rod and the nut.
2. The rotational implant device of claim 1 , wherein the cooperating teeth are disposed on an axial face of the nut and an end of the rod.
3. The rotational implant device of claim 1 , wherein the nut includes an anti-rotation element configured to maintain rotational alignment of the nut within the housing.
4. The rotational implant device of claim 3 , wherein the anti-rotation element includes two or more ears.
5. The rotational implant device of claim 4 , wherein the two or more ears interface with corresponding grooves or recesses in an interior surface of the housing.
6. The rotational implant device of claim 1 , wherein the nut is configured to disengagably interface with the rod.
7. The rotational implant device of claim 6 , further comprising:
an external adjustment device comprising at least one rotatable magnet configured to disengage the one or more cooperative teeth of the nut and the rod such that the first section can be manually rotated independently of the second section from a first position to a second position.
8. The rotational implant device of claim 7 , wherein the at least one rotatable magnet of the external adjustment device is configured to reengage the one or more cooperative teeth, thereby locking the cooperative teeth in the second position.
9. The rotational implant device of claim 8 , wherein a slip clutch is located between the magnet and the lead screw and configured to prevent binding of the magnet and the lead screw.
10. A method for altering rotational alignment of two sections of a long bone in a subject, comprising:
securing an implant having a rod and a housing to different portions of the two sections of the long bone of the subject, wherein the housing includes a rotatable permanent magnet disposed within the housing; wherein a nut is mechanically connected to a lead screw configured to be rotated by the operating of an external adjustment device, and wherein the nut is configured to interface with the rod with one or more cooperating teeth on each of the rod and the nut; and
positioning the external adjustment device in external proximity to the long bone of the subject, the external adjustment device comprising at least one rotatable magnet; and
operating the external adjustment device so that a magnetic field of the at least one rotatable magnet causes the rotatable permanent magnet of the implant to rotate and thereby effectuate a change in the rotational orientation of the housing relative to the rod.
11. The method of claim 10 , wherein the one or more cooperating teeth are disposed on each of an axial face of the nut and an end of the rod.
12. The method of claim 10 , wherein the nut includes an anti-rotation element configured to maintain rotational alignment of the nut within the housing.
13. The method of claim 12 , wherein the anti-rotation element includes at least two ears.
14. The method of claim 13 , wherein the at least two ears interface with corresponding grooves or recesses in an interior surface of the housing.
15. The method of claim 10 , wherein the cooperative teeth of the rod and the nut are configured to be disengageable from one another.
16. The method of claim 15 , wherein the magnet of the external adjustment device is configured to disengage the cooperative teeth of the rod and the nut from one another such that the two sections can be manually rotated independently of one another from a first position to a second position.
17. The method of claim 16 , wherein the magnet of the external adjustment device is configured to reengage the one or more cooperative teeth of the rod and the nut with one another, thereby locking the one or more cooperative teeth in the second position.
18. The method of claim 17 , wherein a slip clutch is located between the magnet and the lead screw and configured to prevent binding of the magnet and the lead screw.