Partially porous bone implant keel

• US 9,949,837 B2
• Filed: 03/07/2013
• Issued: 04/24/2018
• Est. Priority Date: 03/07/2013
• Status: Active Grant

• Current Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Original Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Inventors: Wang, Aiguo, Poggie, Matthew P., Dong, Nicholas Nai Guang
• Primary Examiner(s): WATKINS, MARCIA LYNN
• Application Number:
  US13/788,442
• Publication Number:
  US 20140257507A1
• Time in Patent Office: 1,874 Days
• Field of Search: 623 2014, 623 2016, 623 2017, 623 2021, 623 203, 623 2031, 623 2032, 623 2034, 623 2353, 623 2355
• CPC Class Codes: A61F 2/30749 Fixation appliances for connecting prostheses to the body
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/30907 Nets or sleeves applied to surface of prostheses or in cement
• CPC Class Codes: A61F 2/3094 Designing or manufacturing processes
• CPC Class Codes: A61F 2/3877 Patellae or trochleae
• CPC Class Codes: A61F 2/389 Tibial components A61F2/3868 takes precedence
• CPC Class Codes: A61F 2/461 of knees
• CPC Class Codes: A61F 2002/30011 differing in porosity
• CPC Class Codes: A61F 2002/30179 X-shaped
• CPC Class Codes: A61F 2002/30322 differing in surface structures
• CPC Class Codes: A61F 2002/30451 soldered or brazed or welded
• CPC Class Codes: A61F 2002/30878 with non-sharp protrusions, for instance contacting the bone for anchoring, e.g. keels, pegs, pins, posts, shanks, stems, struts
• CPC Class Codes: A61F 2002/30879 Ribs
• CPC Class Codes: A61F 2002/30884 Fins or wings, e.g. longitudinal wings for preventing rotation within the bone cavity
• CPC Class Codes: A61F 2002/30891 Plurality of protrusions
• CPC Class Codes: A61F 2002/30892 parallel
• CPC Class Codes: A61F 2002/3092 having an open-celled or open-pored structure
• CPC Class Codes: A61F 2002/3093 for promoting ingrowth of bone tissue
• CPC Class Codes: A61F 2002/3097 using laser
• CPC Class Codes: A61F 2002/4619 for extraction
• CPC Class Codes: A61F 2002/4641 : for disconnecting
• CPC Class Codes: Y02P 10/25 : Process efficiency

Abstract

A method for removing a stem portion of an orthopedic implant from a bone comprises exposing an implanted orthopedic implant having a body portion, a stem portion interconnected to the body and a porous metal section forming an interconnection between the body and the stem portion. A cutting tool is mounted on a holder connected to an exposed surface of the orthopedic implant. The porous section is aligned with the cutting tool mounted on the holder. The entire porous section is cut by moving the cutting tool therethrough in a direction transverse to the stem portion axis. The implant body portion is then removed and then the stem portion is removed from the bone. The cutting tool may be a saw or chisel which may be mounted on a guide fixed to the body portion.

Claims

1. A tibial implant comprising:

a substantially solid body portion having a bone contacting surface;

a porous spacer fused to the bone contacting surface of the body portion;

a plurality of substantially solid straight struts fused to the spacer and the bone contacting surface of the body portion; and

a substantially solid stem portion configured for introduction into the medullary canal of a bone, the stem portion including a superior end section spaced from the body portion by the spacer, the superior end section being fused to the spacer and each of the struts to form a one-piece construct,

wherein each of the struts extends from the body portion to the stem portion.

2. A tibial implant comprising:

a substantially solid baseplate having an inferior bone contacting surface and a superior surface configured for receiving a bearing component;

a porous spacer fused to the bone contacting surface of the baseplate;

a plurality of substantially solid straight struts fused to the spacer and the bone contacting surface of the baseplate; and

a substantially solid stem portion configured for introduction into the medullary canal of a tibia and having a superior end section, the stem portion being fused to the spacer and each of the struts to form a one-piece construct, wherein the superior end section of the stem portion is spaced from the bone contacting surface of the baseplate by the spacer, and wherein each of the struts extends from the baseplate to the stem portion.

3. The tibial implant as set forth in claim 2, wherein the stem portion includes two solid wings that form a v-shaped keel.

4. The tibial implant as set forth in claim 3, wherein the bone contacting surface of the baseplate and a superior end of each of the wings are spaced at least 2 mm apart by the spacer.

5. The tibial implant as set forth in claim 2, wherein the spacer has a pore size in a range from 100 to 400 μ

m.

6. The tibial implant as set forth in claim 2, wherein the spacer has pores formed by open polyhedron structures.

7. The tibial implant as set forth in claim 6, wherein the polyhedron structure is an octahedron.

8. The tibial implant as set forth in claim 2, wherein each of the baseplate, the spacer, and the stem portion is made of a metal selected from the group consisting of titanium, titanium alloy and cobalt chrome molybdenum alloy.

9. The tibial implant as set forth in claim 2, wherein a combination of the spacer and each of the struts spans the entire width of the stem portion in a direction orthogonal to a direction that each of the struts extends between the baseplate and the stem portion.

10. The tibial implant as set forth in claim 2, wherein the porosity of the spacer decreases in an inward direction along a medial-lateral plane, the inward direction being directed away from an outer circumferential surface of the baseplate.

11. A tibial implant comprising:

a substantially solid baseplate having an inferior bone contacting surface and a superior surface for receiving a bearing component;

a porous spacer fused to the bone contacting surface of the baseplate;

of plurality of substantially solid straight struts fused to the spacer and the bone contacting surface of the baseplate;

a substantially solid central stem portion having a superior end section fused to the spacer and each of the struts such that the stem portion, the spacer, each of the struts, and the baseplate are all fused from a single metal to form a one-piece construct; and

wings extending outwardly from the stem portion,

wherein the superior end section of the stem portion is spaced at least 2 mm from the bone contacting surface of the baseplate by the spacer,

wherein the spacer, the wings, and the stem portion are in a form of a v-shaped keel,

wherein each of the struts extends from the baseplate to the stem portion, and

wherein the spacer and each of the struts are configured for being cut through with an implant removal tool.

12. The tibial implant as set forth in claim 11, wherein the spacer is made of fused metal powder, each of the struts extends through the spacer, and the stem portion is made of metal powder and is fully dense.

13. The tibial implant as set forth in claim 11, wherein the spacer has a pore size in a range from 100 to 400 μ

m.

14. The tibial implant as set forth in claim 11, wherein the spacer has pores formed by open polyhedron structures.

15. The tibial implant as set forth in claim 14, wherein the polyhedron structure is an octahedron.

16. The tibial implant as set forth in claim 11, wherein the metal of the baseplate, the spacer, and the stem portion is selected from the group consisting of titanium, titanium alloy and cobalt chrome molybdenum alloy.

17. The tibial implant as set forth in claim 11, wherein the implant removal tool is a saw or chisel.