Disk prosthesis for cervical vertebrae

• US 6,517,580 B1
• Filed: 03/09/2000
• Issued: 02/11/2003
• Est. Priority Date: 03/03/2000
• Status: Expired

• Current Assignee: Scient'x SA (Alphatec Holdings Incorporated)
• Original Assignee: Scient'X Societe A Responsabilite Limited
• Inventors: Ramadan, Aymen, Bühler, Markus
• Primary Examiner(s): Willse, David H.
• Assistant Examiner(s): GHERBI, SUZETTE JAIME J
• Application Number:
  US09/521,896
• Time in Patent Office: 1,069 Days
• Field of Search: 623/17.11, 623/17.14, 623/17.15, 623/17.16
• US Class Current: 623/17.15
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/4425 made of articulated components
• CPC Class Codes: A61F 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2002/30016 differing in hardness, e.g. Vickers, Shore, Brinell
• CPC Class Codes: A61F 2002/30112 Rounded shapes, e.g. with rounded corners
• CPC Class Codes: A61F 2002/30138 Convex polygonal shapes
• CPC Class Codes: A61F 2002/30324 differing in thickness
• CPC Class Codes: A61F 2002/30332 Conically- or frustoconically-shaped protrusion and recess
• CPC Class Codes: A61F 2002/30354 Cylindrically-shaped protrusion and recess, e.g. cylinder of circular basis
• CPC Class Codes: A61F 2002/30448 using adhesives
• CPC Class Codes: A61F 2002/30563 having elastic means or damping means, different from springs, e.g. including an elastomeric core or shock absorbers
• CPC Class Codes: A61F 2002/30604 modular
• CPC Class Codes: A61F 2002/30616 Sets comprising a plurality of prosthetic parts of different sizes or orientations
• CPC Class Codes: A61F 2002/30662 with rotation-limiting means
• CPC Class Codes: A61F 2002/30685 Means for reducing or preventing the generation of wear particulates
• CPC Class Codes: A61F 2002/30733 Inserts placed into an endoprosthetic cavity, e.g. for modifying a material property
• CPC Class Codes: A61F 2002/30808 parallel
• CPC Class Codes: A61F 2002/30828 parallel
• CPC Class Codes: A61F 2002/30841 Sharp anchoring protrusions for impaction into the bone, e.g. sharp pins, spikes
• CPC Class Codes: A61F 2002/30892 parallel
• CPC Class Codes: A61F 2002/30904 : serrated profile, i.e. saw-toothed
• CPC Class Codes: A61F 2002/443 : having two transversal endplates and at least one intermediate component
• 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 2220/005 : using adhesives
• CPC Class Codes: A61F 2230/0004 : Rounded shapes, e.g. with rounded corners
• CPC Class Codes: A61F 2230/0017 : Angular shapes
• CPC Class Codes: A61F 2250/0019 : differing in hardness, e.g. Vickers, Shore, Brinell
• CPC Class Codes: A61F 2250/0036 : differing in thickness
• CPC Class Codes: A61F 2310/00023 : Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/00203 : containing alumina or aluminium oxide
• CPC Class Codes: A61F 2310/00239 : containing zirconia or zirconium oxide ZrO2
• CPC Class Codes: A61F 2310/00407 : Coating made of titanium or of Ti-based alloys
• CPC Class Codes: A61F 2310/00796 : Coating or prosthesis-covering structure made of a phosphorus-containing compound, e.g. hydroxy(l)apatite

Abstract

A disk prosthesis for cervical vertebrae. The prosthesis includes a spherical cap formed on a first insert, while a spherical cup is formed on a second inset, two inserts made of ceramic material, one of the inserts being mounted on a first plate while the other insert is mounted on a second plate in such a manner that the center of rotation of the joint is substantially centered relative to the edges of the plates, a spherical cup possessing a contact surface area that is not less than that of the spherical cap and being connected via an annular molding to the base of the insert, and a plate provided with the insert having the spherical cap includes an annular setback to leave clearance for the annular molding.

Claims

1. A disk prosthesis for cervical vertebrae, the prosthesis being of the type comprising:

first and second plates designed to be fixed to adjacent cervical vertebrae; and

a ball joint interposed between the two plates mounted in a superposed position, the joint being constituted by a spherical cap co-operating with a spherical cup,

wherein;

the spherical cap is provided on a first insert, while the spherical cup is provided on a second insert;

each insert is made of a ceramic material and possesses a base of circular right cross-section;

one of the inserts is mounted on the first plate while the other insert is mounted on the second plate in such a manner that the center of rotation of the joint lies substantially centered relative to the edges of the plates so as to be centered in the sagittal plane and in the frontal plane of the vertebrae;

the spherical cup possesses a contact area that is not less than the contact area of the spherical cap and is connected via an annular molding to the base of the insert; and

the plate provided with the insert having the spherical cap has an annular setback to leave clearance for the annular molding of the spherical cup during movements of the plates.

2. A disk prosthesis according to claim 1, wherein each plate is organized to present a blind housing for receiving an insert.

3. A disk prosthesis according to claim 1, wherein each plate is organized to present a blind housing for receiving an insert, and wherein each insert possesses a base whose circular right cross-section tapers from the spherical cap or the spherical cup, and matches the blind housing of complementary profile.

4. A disk prosthesis according to claim 1, wherein the inserts are made of ceramic materials of different hardnesses.

5. A disk prosthesis according to claim 4, wherein the insert fitted with the spherical cup is made of zirconium oxide, while the insert fitted with the spherical cap is made of aluminum oxide.

6. A disk prosthesis according to claim 2, including a damping element mounted in the end of the blind housing so as to be interposed between the insert and the plate.

7. A disk prosthesis according to claim 1, wherein the plate fitted with the spherical cap extends over the plate fitted with the spherical cup.

8. A disk prosthesis according to claim 1, wherein the plate extending over the other plate has a top outer face that presents a profile that is convex in the sagittal plane.

9. A disk prosthesis according to claim 1, wherein each plate possesses an outer face of profile that is plane.

10. A disk prosthesis according to claim 8, wherein the outer face of at least one of the plates is provided with anchoring notches for anchoring in the vertebrae.

11. A disk prosthesis according to claim 10, wherein the anchoring notches are constituted by ribs that are parallel to one another and parallel to the posterior edges of the plates.

12. A disk prosthesis according to claim 8, wherein the outer face of at least one of the plates is provided with two studs for preventing the cage from sliding.

13. A disk prosthesis according to claim 1, wherein each plate is provided on its posterior edges with two positioning holes for the studs of a tool for holding both plates simultaneously, which plates, when in this position, form an insertion cone in the sagittal plane.

14. A disk prosthesis according to claim 1, wherein each plate has an anterior edge of profile that is concave in the transverse plane.