TELESCOPING IM NAIL AND ACTUATING MECHANISM

• US 20110230883A1
• Filed: 05/17/2011
• Published: 09/22/2011
• Est. Priority Date: 03/19/2010
• Status: Active Grant

• Current Assignee: Smith & Nephew Incorporated (Smith & Nephew PLC)
• Original Assignee: Smith & Nephew Incorporated (Smith & Nephew PLC)
• Inventors: Zahrly, Daniel C., Evans, David L., Janna, Sied W.
• Granted Patent: US 8,777,947 B2
• Time in Patent Office: Days
• US Class Current: 606/63
• CPC Class Codes: A61B 17/7216 for bone lengthening or compression A61B17/7258 takes precedence
• CPC Class Codes: A61B 17/7225 for bone compression
• CPC Class Codes: A61B 2017/00411 actuated by application of energy from an energy source outside the body
• CPC Class Codes: A61B 2017/00876 magnetic
• CPC Class Codes: A61B 2017/00991 Telescopic means

Abstract

A length-adjustable IM nail system includes a telescoping IM nail with proximal and distal bodies. An inner magnet within the proximal body is connected to a threaded rod which, in turn, is connected to the distal body. The threaded rod passes through a threaded block which is connected to the proximal body. The position of the distal end of the threaded rod is fixed with respect to the distal body, but may rotate freely within this fixed position. An actuator is also disclosed that includes a pair of rotating magnets disposed in an angular relationship with each other and the axis of the IM nail and the patient'"'"'s limb. Rotation of these outer magnets in the same direction results in rotation of the inner magnet and threaded rod and a telescoping axial movement of the threaded block and proximal body with respect to the distal body.

Claims

1. A length adjustable intramedullary nail system, comprising:

an intramedullary nail, comprising;

a proximal outer body;

a distal body having a portion received by the proximal outer body;

a threaded shaft coupled to the distal body to rotate relative thereto;

an inner magnet received by the proximal outer body and coupled to the threaded shaft; and

a threaded block coupled to the proximal outer body, the threaded shaft passing through the threaded block such that rotation of the inner magnet and the threaded shaft causes relative axial movement between a) the inner magnet, the threaded shaft and the distal body and b) the proximal outer body.

2. The system of claim 1 wherein the threaded shaft is connected to the distal body at a fixed position such that the threaded shaft and the distal body are axially fixed relative to each other.

3. The system of claim 1 further comprising an actuator including at least one outer magnet.

4. The system of claim 3 further comprising a housing rotatably accommodating the at least one outer magnet and accommodating a drive mechanism configured to rotate the outer magnet about an axis that is parallel to an axis of the inner magnet, such that rotation of the outer magnet imparts rotation to the inner magnet.

5. The system of claim 3 wherein the at least one outer magnet comprises two outer magnets.

6. The system of claim 5 further comprising first and second housings each rotatably accommodating one of the outer magnets and each accommodating a drive mechanism configured to rotate the one of the outer magnets about an axis that is parallel to an axis of the inner magnet, such that rotation of the outer magnets imparts rotation to the inner magnet.

7. The system of claim 6 wherein the housings are coupled together to maintain the first and second outer magnets in a spaced-apart angular relationship to permit the intramedullary nail to be positioned between the first and second outer magnets.

8. The system of claim 7 further comprising a linkage coupling the first and second outer magnets and configured to impart rotation to the first and second outer magnets in the same direction to impart rotation to the inner magnet and threaded shaft.

9. The system of claim 3 further comprising a circular track accommodating the at least one outer magnet.

10. The system of claim 3 wherein the actuator comprises a user interface that displays the magnitude of axial distraction or axial compaction of the intramedullary nail.

11. The system of claim 1 wherein the distal body of the intramedullary nail includes at least one transverse hole for receiving a fixation element to couple the distal body to a patient'"'"'s bone.

12. A method for adjusting the length of an intramedullary nail, comprising:

placing an actuator about a patient'"'"'s limb such that an outer magnet of the actuator is disposed relative to an intramedullary nail located within the patients limb, the intramedullary nail including first and second bodies configured for relative axial movement and an inner magnet; and

rotating the outer magnet to impart rotation to the inner magnet that results in relative axial movement of the first and second bodies to adjust the length of the intramedullary nail.

13. The method of claim 12 wherein the outer magnet is disposed with a rotation axis of the outer magnet parallel to an axis of the intramedullary nail.

14. The method of claim 12 wherein the outer magnet is disposed with a rotation axis of the outer magnet perpendicular to an axis of the intramedullary nail.

15. The method of claim 12 wherein the outer magnet is disposed with a rotation axis of the outer magnet non-parallel to an axis of the intramedullary nail.

16. An actuator, comprising:

at least two magnets; and

a linkage coupling the at least two magnets and configured to impart rotation to the first and second outer magnets in the same direction; and

a user interface that displays the magnitude of axial distraction or axial compaction of an intramedullary nail caused by rotation of the magnets.

17. The actuator of claim 16 further comprising a drive mechanism configured to rotate a first of the two magnets and the linkage is configured such that rotation imparted to the first magnet by the drive mechanism also results in rotation of the second magnet.

18. The actuator of claim 16 wherein the linkage comprises a linkage assembly having an arcuate linkage coupled to a first linkage and a second linkage, the first linkage coupling the arcuate linkage to the first magnet and the second linkage coupling the arcuate linkage to the second magnet.

19. The actuator of claim 16 wherein the at least two magnets are configured to rotate about parallel axes and in a same direction.

20. The actuator of claim 16 wherein the linkage maintains the at least two magnets in an angular relationship with respect to each other in a range from about 120 to about 180°

.

21. An actuator, comprising:

at least one magnet having an axis oriented to be non-parallel to an axis of an intramedullary nail, the magnet being configured for rotation about the magnet axis; and

a user interface that displays the magnitude of axial distraction or axial compaction of an intramedullary nail caused by rotation of the magnet.

22. The actuator of claim 21 comprising at least a second magnet coupled to the first magnet and having an axis oriented to be non-parallel to the intramedullary nail axis, the second magnet being configured for rotation about the second magnet axis.

23. The actuator of claim 21 comprising at least a second magnet coupled to the first magnet and having an axis oriented to be parallel to the intramedullary nail axis, the second magnet being configured for rotation about the second magnet axis.