Expandable implant, instrument, and method

• US 20070255409A1
• Filed: 04/27/2006
• Published: 11/01/2007
• Est. Priority Date: 04/27/2006
• Status: Active Grant

• Current Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: SDGI Holdings Incorporated (Medtronic Plc)
• Inventors: Dickson, Andrew, Shaffrey, Christopher, Potts, Eric, Braddock, Danny, Karahalios, Dean, Harrop, James
• Granted Patent: US 7,914,581 B2
• Time in Patent Office: Days
• US Class Current: 623/17.110
• CPC Class Codes: A61B 2017/0256 for the spine
• CPC Class Codes: A61F 2/28 Bones joints A61F2/30
• CPC Class Codes: A61F 2/30744 End caps, e.g. for closing an endoprosthetic cavity
• CPC Class Codes: A61F 2/44 for the spine, e.g. vertebrae, spinal discs
• CPC Class Codes: A61F 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2002/2817 Bone stimulation by chemical reactions or by osteogenic or biological products for enhancing ossification, e.g. by bone morphogenetic or morphogenic proteins [BMP] or by transforming growth factors [TGF]
• CPC Class Codes: A61F 2002/2835 Bone graft implants for filling a bony defect or an endoprosthesis cavity, e.g. by synthetic material or biological material
• CPC Class Codes: A61F 2002/30062 (bio)absorbable, biodegradable, bioerodable, (bio)resorbable, resorptive
• CPC Class Codes: A61F 2002/30092 using shape memory or superelastic materials, e.g. nitinol
• CPC Class Codes: A61F 2002/30171 rosette- or star-shaped
• CPC Class Codes: A61F 2002/30331 made by longitudinally pushing a protrusion into a complementarily-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2002/30372 with additional means for limiting said translation
• CPC Class Codes: A61F 2002/30405 made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/3052 unrestrained in only one direction, e.g. moving unidirectionally
• CPC Class Codes: A61F 2002/30522 releasable, e.g. using a releasable ratchet
• CPC Class Codes: A61F 2002/30523 by means of meshing gear teeth
• CPC Class Codes: A61F 2002/3054 about a connection axis or implantation axis for selecting any one of a plurality of radial orientations between two modular parts, e.g. Morse taper connections, at discrete positions, angular positions or continuous positions
• CPC Class Codes: A61F 2002/3055 for adjusting length
• CPC Class Codes: A61F 2002/30571 Leaf springs
• CPC Class Codes: A61F 2002/30594 slotted, e.g. radial or meridian slot ending in a polar aperture, non-polar slots, horizontal or arcuate slots
• CPC Class Codes: A61F 2002/30601 : telescopic
• CPC Class Codes: A61F 2002/30616 : Sets comprising a plurality of prosthetic parts of different sizes or orientations
• CPC Class Codes: A61F 2002/30677 : Means for introducing or releasing pharmaceutical products, e.g. antibiotics, into the body
• CPC Class Codes: A61F 2002/30772 : Apertures or holes, e.g. of circular cross section
• CPC Class Codes: A61F 2002/30841 : Sharp anchoring protrusions for impaction into the bone, e.g. sharp pins, spikes
• CPC Class Codes: A61F 2002/4627 : with linear motion along or rotating motion about the instrument axis or the implantation direction, e.g. telescopic, along a guiding rod, screwing inside the instrument
• CPC Class Codes: A61F 2002/4628 : with linear motion along or rotating motion about an axis transverse to the instrument axis or to the implantation direction, e.g. clamping
• CPC Class Codes: A61F 2210/0004 : bioabsorbable
• CPC Class Codes: A61F 2210/0014 : using shape memory or superelastic materials, e.g. nitinol
• CPC Class Codes: A61F 2220/0025 : Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0033 : made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2230/005 : Rosette-shaped, e.g. star-shaped
• CPC Class Codes: A61F 2310/00011 : Metals or alloys
• CPC Class Codes: A61F 2310/00179 : Ceramics or ceramic-like structures
• CPC Class Codes: A61F 2310/00359 : Bone or bony tissue

Abstract

Embodiments of the invention include expandable, implantable devices and methods. Devices expand linearly to provide secure fixation between or among anatomical structures. In some embodiments, an implant replaces one or more vertebral bodies of the spine.

Claims

1. An expandable medical implant for supporting skeletal structures comprising:

a first tubular member with a connection end and an opposite skeletal interface end;

a second tubular member with a connection end configured to engage with the connection end of the first tubular member, the second tubular member having an opposite skeletal interface end; and

a key pin fixed to the first tubular member and positioned in a slot in the second tubular member so that the key pin guides translation between the first tubular member and the second tubular member.

2. The expandable medical implant of claim 1 wherein the first tubular member fits within the second tubular member.

3. The expandable medical implant of claim 1 wherein the first tubular member includes a relief cut to facilitate portions of the first tubular member flexing away from the second tubular member to permit translation between the first and second tubular members.

4. The expandable medical implant of claim 1 wherein the first tubular member includes a set of adjacent protrusions.

5. The expandable medical implant of claim 4 wherein the second tubular member includes a set of protrusions that are not all adjacent and that interdigitate with one or more of the adjacent protrusions.

6. The expandable medical implant of claim 1 wherein the first and second tubular members are generally cylindrical.

7. The expandable medical implant of claim 1 wherein the key pin contributes to torsional stability between the first tubular member and the second tubular member.

8. The expandable medical implant of claim 1 wherein the key pin is a stop for movement of the first tubular member relative to the second tubular member.

9. The expandable medical implant of claim 1 further comprising an insertion instrument for expanding the implant, wherein the implant progressively locks as expanded by motion of at least a portion of the insertion instrument in a first direction, and the locked implant releases by motion of the portion of the insertion instrument in a generally opposite direction.

10. The expandable medical implant of claim 9 wherein the locked implant is released by applying a force to the key pin.

11. An expandable medical implant for supporting skeletal structures comprising:

a first tubular member with a connection end and an opposite skeletal interface end;

a second tubular member with a connection end configured to engage with the connection end of the first tubular member, the second tubular member having an opposite skeletal interface end;

wherein the second tubular member intermittently locks relative to the first tubular member as the implant is expanded; and

an insertion instrument for translating the first tubular member relative to the second tubular member comprising;

a first tip for attaching to the skeletal interface end of the first tubular member,

a second tip for attaching to the skeletal interface end of the second tubular member, and

a spreader mechanism for translating the first tip away from the second tip;

wherein moving the first tip toward the second tip results in the first tubular member being released relative to the second tubular member to permit the expandable medical implant to be reduced in length.

12. The expandable medical implant of claim 11 wherein the second tip includes a capture mechanism for engaging a portion of the implant that releases locking between the first and second tubular members.

13. The expandable medical implant of claim 12 wherein the capture mechanism connects the insertion instrument to the first and second tubular members to facilitate positioning or removal of the first and second tubular members.

14. The expandable medical implant of claim 11 wherein the first tip includes a capture mechanism for engaging a portion of the implant that releases locking between the first and second tubular members.

15. The expandable medical implant of claim 14 wherein the capture mechanism connects the insertion instrument to the first and second tubular members to facilitate positioning or removal of the first and second tubular members.

16. The expandable medical implant of claim 11 further comprising a set of two or more variously sized first interchangeable tips that may be placed one at a time on the insertion instrument in the position of the first tip to accommodate first tubular members of different, matching sizes.

17. The expandable medical implant of claim 11 further comprising a set of two or more variously sized second interchangeable tips that may be placed one at a time on the insertion instrument in the position of the second tip to accommodate second tubular members of different, matching sizes.

18. An end member for a medical implant having a length, the end member configured to interface with a skeletal structure at the end of its length, comprising:

an end cap with a thickness that provides connection to the medical implant and connection to the skeletal structure; and

a shoe for attachment to the end cap, the shoe spanning at least a portion of an opening through the end cap, and providing at least in part an interface with the skeletal structure.

19. The end member of claim 18 wherein the medical implant is a corpectomy device.

20. The end member of claim 18 wherein the end cap varies in thickness such that placement of the end member on the medical implant creates an interface with the implant that is not parallel to the length of the implant.

21. The end member of claim 20 wherein the end member and medical implant match the natural angles of a spinal curvature.

22. The end member of claim 21 wherein the angles of spinal curvature are lordotic angles.

23. The end member of claim 18 wherein the end cap includes surface irregularities to aid interface with the skeletal structure.

24. The end member of claim 23 wherein the surface irregularities are sharp spikes that penetrate the skeletal structure.

25. The end member of claim 18 wherein the end cap includes cap connectors for coupling the end cap to the medical implant.

26. The end member of claim 25 wherein the cap connectors are pins.

27. The end member of claim 25 wherein the medical implant includes an opening for receiving a cap connector, the opening having a cut from the opening through at least of portion of the surrounding material to provide a living hinge to securely receive the cap connector in the opening.

28. The end member of claim 18 wherein the shoe is convexly shaped relative to the end member.

29. The end member of claim 18 wherein the shoe is concavely shaped relative to the end member.

30. The end member of claim 18 wherein the shoe is at least in part a bioresorbable material.

31. The end member of claim 18 wherein the shoe is at least in part a bioactive substance.

32. The end member of claim 18 wherein the shoe includes shoe connectors for coupling the shoe to the medical implant.

33. The end member of claim 18 wherein the shoe includes hinges between the shoe connectors.

34. A method of placing a medical implant between skeletal structures with an insertion instrument comprising the acts of:

accessing a surgical site;

expanding the medical implant to fit in a space between skeletal structures by moving at least a portion of the insertion instrument in a first direction, wherein the medical implant progressively locks as expanded; and

if the locked implant needs to be released from the locked position, releasing the locked implant by moving of the portion of the insertion instrument in a generally opposite direction.

35. The method of claim 34 wherein the act of expanding the medical implant by moving at least a portion of the insertion instrument in a first direction includes rotating the portion of the insertion instrument in a clockwise direction.

36. The method of claim 34 wherein the act of releasing the locked implant by moving of the portion of the insertion instrument in a generally opposite direction includes rotating the portion of the insertion instrument in a counter-clockwise direction.

37. An expandable device for supporting skeletal structures comprising:

an implant means for expanding into a space between skeletal structures in a progressively locked state;

an instrument means for expanding the implant into the space by movement of at least a portion of the instrument in a first direction, wherein movement of the at least a portion of the instrument in a generally opposite direction releases the locked state of the implant.