Cartilage implants and methods of use

• US 20090228104A1
• Filed: 03/06/2008
• Published: 09/10/2009
• Est. Priority Date: 03/06/2008
• Status: Active Grant

• Current Assignee: Moirai Orthopaedics, LLC
• Original Assignee: Moirai Orthopaedics, LLC
• Inventors: Cook, Stephen D., Strzepa, Peter
• Granted Patent: US 8,043,375 B2
• Time in Patent Office: Days
• US Class Current: 623/14.120
• CPC Class Codes: A61F 2/30756 Cartilage endoprostheses A61F2/3603 takes precedence
• CPC Class Codes: A61F 2/38 for elbows or knees
• CPC Class Codes: A61F 2/3804 for elbows
• CPC Class Codes: A61F 2/40 for shoulders
• CPC Class Codes: A61F 2/4261 for wrists
• CPC Class Codes: A61F 2002/30112 Rounded shapes, e.g. with rounded corners
• CPC Class Codes: A61F 2002/30125 elliptical or oval
• CPC Class Codes: A61F 2002/30299 umbrella-shaped or mushroom-shaped
• CPC Class Codes: A61F 2002/30822 Circumferential grooves
• 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 2230/0008 elliptical or oval
• CPC Class Codes: A61F 2230/0093 Umbrella-shaped, e.g. mushroom-shaped
• CPC Class Codes: A61F 2310/00011 Metals or alloys
• CPC Class Codes: A61F 2310/00161 Carbon; Graphite
• CPC Class Codes: A61F 2310/00173 Graphite
• CPC Class Codes: A61F 2310/00179 Ceramics or ceramic-like structures
• CPC Class Codes: A61F 2310/00574 Coating or prosthesis-covering structure made of carbon, e.g. of pyrocarbon
• CPC Class Codes: A61F 2310/00796 Coating or prosthesis-covering structure made of a phosphorus-containing compound, e.g. hydroxy(l)apatite
• CPC Class Codes: Y10S 623/908 Bone

Abstract

Cartilage implant devices, and method of using the same, are provided. The implant devices have circular, or oblong, articular ends. The articular ends have a convex upper face and a concave lower face, the convex upper face blending to the concave lower face, and the concave lower face having a curvature less than the curvature of the convex upper face. The implant devices further have a stem extending from the concave lower face away from the upper face, the stem having a maximum radius at the convex lower face and tapering to lesser radius along the length of the stem.

Claims

1. ) A cartilage implant comprising:

a. an articular end having a circular perimeter, a convex upper face, and a concave lower face, the convex upper face having a spherical radius and the concave lower face having a spherical radius; and

b. a stem extending from the concave lower face away from the convex upper face along a vertical axis, the stem having a maximum stem circular perimeter at the intersection of the stem and the concave lower face, the maximum stem circular perimeter less than the articular end circular perimeter.

2. ) The cartilage implant of claim 1, wherein the stem circular perimeter decreases from the maximum stem circular perimeter to a lesser stem circular perimeter along the vertical axis of the stem.

3. ) The cartilage implant of claim 1, wherein the spherical radius of the convex upper face is greater than the spherical radius of the concave lower face, and the stem has a cylindrical portion extending from the concave lower face away from the convex upper face along the vertical axis, and a conical portion extending from the cylindrical portion away from the convex upper face along the vertical axis.

4. ) The cartilage implant of claim 3, wherein the cylindrical portion has a length ranging from about one millimeter to about five millimeters;

and the conical portion has a length ranging from about two millimeters to about fifteen millimeters.

5. ) The cartilage implant of claim 1, wherein the diameter of the articular end circular perimeter ranges from about 10 millimeters to about 20 millimeters, the convex upper face having a spherical radius of about 32 millimeters, the concave lower face having a spherical radius of about 30 millimeters, the cylindrical portion of the stem having a diameter of from about 4 millimeters to about 8 millimeters, and the stem having a length from about 10 millimeters to about 20 millimeters.

6. ) The cartilage implant of claim 4, wherein the maximum diameter of the articular end circular perimeter is selected from the group consisting of about 12.5 millimeters, about 15 millimeters, about 17.5 millimeters, and about 20 millimeters, the cylindrical portion of the stem having a maximum diameter selected from the group consisting of about 5.5 millimeters, about 6.25 millimeters, about 6.75 millimeters, and about 7.25 millimeters, and the implant having an overall vertical length selected from the group consisting of about 13 millimeters, about 14.1 millimeters, about 15.2 millimeters, and about 16.5 millimeters.

7. ) The cartilage implant of claim 3, wherein a portion of the conical portion of the stem is comprised of circumferential grooves.

8. ) The cartilage implant of claim 7, wherein the circumferential grooves are defined by a partial torus having a tubular radius of from about 0.25 millimeters to about 1.5 millimeters, and the circumferential grooves are spaced apart at a distance of from about 1 millimeter to about 3 millimeters from each other.

9. ) The cartilage implant of claim 1, wherein the articular end and the stem comprise graphite and pyrocarbon.

10. ) The cartilage implant of claim 9, wherein the articular end and the stem comprise a graphite core and a pyrocarbon coating, the pyrocarbon coating having an elastic modulus from about 15 GPa to about 22 GPa, the pyrocarbon coating having an average thickness ranging from about 100 to about 1000 microns.

11. ) The cartilage implant of claim 10, wherein the pyrocarbon coating has an elastic modulus of about 20 GPa and a strength of at least 400 MPa.

12. ) The cartilage implant of claim 9, wherein the upper face and circular perimeter of the articular end are polished, and the lower face and stem are coated with hydroxyapatite.

24. ) A method of repair of articular cartilage comprising:

a. making an incision into a patient;

b. locating articular cartilage having a lesion;

c. selecting a cartilage implant of claim 1 having dimensions compatible with the lesion;

d. forming a hole through the cartilage and subchondral bone and into the cancellous bone of the patient; and

e. inserting the cartilage implant into the hole so that the lower surface abuts against the prepared subchondral bone and the stem abuts against the prepared cancellous bone.

25. ) The method of claim 24, wherein forming the hole includes placement of autograft, allograft bone, or various bone graft substitute material into the lesion.

26. ) A method of repair of articular cartilage comprising:

a. making an incision into a patient;

b. locating articular cartilage having a lesion;

c. selecting a cartilage implant of claim 11 having dimensions compatible with the lesion;

d. forming a hole through the cartilage and subchondral bone and into the cancellous bone of the patient; and

e. inserting the cartilage implant into the hole so that the lower surface abuts against the prepared subchondral bone and the stem abuts against the prepared cancellous bone.

27. ) The method of claim 26, wherein forming the hole includes placement of autograft, allograft bone, or various bone graft substitute material into the lesion.

13. ) A cartilage implant comprising:

a. an articular end having an oval perimeter, a convex upper face, and a concave lower face, the convex upper face having a first circular pitch radius and a first circular roll radius, the concave lower face having a first surface comprising a second circular pitch radius and a second circular roll radius, and at least two second surfaces each external to the first surface and each tangent to a portion of the first surface, each second surface having a third circular pitch radius and a third circular roll radius, the convex upper face blending into a rim, wherein at least a first and a second portion of the rim extends at least a first distance along the vertical axis and a third and a fourth portion of the rim tapers inward along the vertical axis, the rim blending into the concave lower face; and

b. a stem extending from the concave lower face away from the convex upper face, the stem having an oval shaped perimeter in at least one plane perpendicular to the vertical axis.

14. ) The cartilage implant of claim 13, wherein the oval articular end has a maximum length, along the horizontal axis of from about 15 millimeters to about 40 millimeters;

the oval articular end has a maximum length, along the depth axis, ranging from about 10 millimeters to about 30 millimeters; and

the cartilage implant has a maximum length along the vertical axis ranging from about 10 millimeters to about 35 millimeters.

15. ) The cartilage implant of claim 13, wherein the first, second and third circular pitch radii are each independently selected from the group consisting of from about 15 millimeters to about 30 millimeters, from about 20 millimeters to about 25 millimeters, about 22 millimeters, and about 19.5 millimeters, the first, second, and third circular roll radii are each independently selected from the group consisting of from about 20 millimeters to about 40 millimeters, from about 25 millimeters to about 35 millimeters, about 32 millimeters, about 29.5 millimeters, and about 19.5 millimeters.

16. ) The cartilage implant of claim 15, wherein the maximum roll radius of the first surface of the concave lower face is bounded by an angle selected from the group consisting of from about 5 degrees to about 25 degrees and from about 10 degrees to about 20 degrees.

17. ) The cartilage implant of claim 13, wherein the stem has a first portion and a second portion, the first portion extending from the lower concave face a length in the vertical direction away from the upper convex face, the second portion extending from the first portion a length in the vertical direction away from the upper convex face, wherein the first portion tapers inward along its horizontal axis in the vertical direction and has a uniform length along its depth axis in the vertical direction, the second portion tapers inward along its horizontal axis and its depth axis in the vertical direction, the first and second portion blend into each other, the length of the first portion along the vertical is selected from the group consisting of 2 millimeters to about 10 millimeters and from about 2 millimeters to about 8 millimeters, the length of the second portion along the vertical is selected from the group consisting of from about 2 millimeters to about 25 millimeters, from about 5 millimeters to about 20 millimeters, and from about 5 millimeters to about 10 millimeters.

18. ) The cartilage implant of claim 17, wherein the second portion of the stem comprises grooves.

19. ) The cartilage implant of claim 18, wherein the grooves are defined by a partial, oval, non-planar torus having a tubular radius of from about 0.25 millimeters to about 1.5 millimeters, and the grooves are spaced apart at a distance of from about 1 millimeter to about 3 millimeters from each other.

20. ) The cartilage implant of claim 19, wherein the articular end and the stem comprise graphite and pyrocarbon.

21. ) The cartilage implant of claim 20, wherein the articular end and the stem comprise a graphite core and a pyrocarbon coating, the pyrocarbon coating having an elastic modulus from about 15 GPa to about 22 GPa, the pyrocarbon coating having an average thickness ranging from about 100 to about 1000 microns.

22. ) The cartilage implant of claim 21, wherein the pyrocarbon coating has an elastic modulus of about 20 GPa and a strength of at least 400 MPa.

23. ) The cartilage implant of claim 22, wherein the upper face and oval perimeter of the articular end are polished, and the lower face and stem are coated with hydroxyapatite.