Artificial disc prosthesis

• US 7,763,075 B2
• Filed: 02/24/2006
• Issued: 07/27/2010
• Est. Priority Date: 04/04/2003
• Status: Expired due to Fees

• Current Assignee: Theken Spine LLC (Orthofix Medical Inc.)
• Original Assignee: Theken Spine LLC (Orthofix Medical Inc.)
• Inventors: Theken, Randall R., Navarro, Richard R., Ananthan, Bharadwaj
• Primary Examiner(s): Robert; Eduardo C
• Assistant Examiner(s): HARVEY, JULIANNA NANCY
• Application Number:
  US11/361,131
• Publication Number:
  US 20060259143A1
• Time in Patent Office: 1,614 Days
• Field of Search: 606/61, 623 1711- 1716
• US Class Current: 623/17.15
• CPC Class Codes: A61F 2/442 Intervertebral or spinal discs, e.g. resilient non-disc-shaped intervertebral inflatable pockets A61F2/441; non-disc-shaped intervertebral fusion implants A61F2/4455
• CPC Class Codes: A61F 2002/30372 with additional means for limiting said translation
• CPC Class Codes: A61F 2002/30383 made by laterally inserting a protrusion, e.g. a rib into a complementarily-shaped groove
• CPC Class Codes: A61F 2002/30462 retained or tied with a rope, string, thread, wire or cable
• 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 2002/30884 Fins or wings, e.g. longitudinal wings for preventing rotation within the bone cavity
• CPC Class Codes: A61F 2002/30892 parallel
• CPC Class Codes: A61F 2002/30904 serrated profile, i.e. saw-toothed
• CPC Class Codes: A61F 2002/3097 using laser
• CPC Class Codes: A61F 2002/4666 for measuring force, pressure or mechanical tension
• 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 2220/0075 sutured, ligatured or stitched, retained or tied with a rope, string, thread, wire or cable
• CPC Class Codes: A61F 2310/00017 Iron- or Fe-based alloys, e.g. stainless steel
• CPC Class Codes: A61F 2310/00023 Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/00029 Cobalt-based alloys, e.g. Co-Cr alloys or Vitallium

Abstract

A visco-elastic motion-limiting artificial intervertebral disc prosthesis is provided that mimics the physiologic function of a normal spinal disc. The disc comprises upper and lower endplates having therewithin channels or openings for optionally receiving one or more motion-limiting members fitted on each end with an enlarged portion. One or more compression stops is provided between the upper and lower endplates. Additionally, an elastomeric cushion is disposed between the endplates and surrounds the motion-limiting members. Also, force transducers and microelectronics can be utilized to provide data to the surgeon or the patient regarding the load state of the disc.

Claims

1. A spinal disc prosthesis, comprising:

a first endplate and a second endplate, each of said first endplate and said second endplate having a respective bone-contacting surface for attaching to respective vertebrae and a respective non-bone-contacting surface opposite said respective bone-contacting surface;

a polymeric member interposed between and adhered to said non-bone-contacting surfaces of said respective endplates;

a compression stop having a first substantially planar uninterrupted contact surface on a surface facing said second endplate, and a second substantially uninterrupted contact surface on a surface facing said first endplate;

wherein in a first position, said first substantially planar uninterrupted contact surface does not contact said second substantially uninterrupted contact surface, and said first endplate and said second endplate are substantially unconstrained to relative movement about six degrees of freedom; and

wherein in a second position, said first substantially planar uninterrupted contact surface contacts said second substantially uninterrupted contact surface, and said first endplate and said second endplate are substantially constrained against relative translation in one direction along the cephalad-caudal axis, but are substantially unconstrained in relative translation and rotation about all other axes; and

electronics contained within said compression stop.

2. The spinal disc prosthesis of claim 1, wherein said electronics are hermetically sealed within said compression stop.

3. A spinal disc prosthesis, comprising:

a first endplate and a second endplate, each of said first endplate and said second endplate having a respective bone-contacting surface for attaching to respective vertebrae and a respective non-bone-contacting surface opposite said respective bone-contacting surface;

a polymeric member interposed between and adhered to said first and second endplates, wherein said polymeric member has an annular shape having an empty central region defining an interior of said polymeric member;

at least one member on a non-bone-contacting surface of one of said first or second endplates, said member having at least one surface parallel to a longitudinal axis of said prosthesis and suitable to transmit force between said first and second endplates under at least some conditions, said member being located at least partially within said empty central region of said polymeric member; and

at least one flat force sensor positioned within one of said first endplate or said second endplate, wherein said sensor has a direction of force measurement that is oriented in a predetermined direction relative to said prosthesis;

wherein said prosthesis comprises three of said sensors located at locations that form vertices of a triangle; and

wherein one of said sensors is located substantially on an anterior-posterior centerline of said prosthesis and two other of said sensors are located one on each side of said anterior-posterior centerline.

4. The prosthesis of claim 3, wherein said prosthesis permits relative motion between said first endplate and said second endplate.

5. The prosthesis of claim 3, wherein said sensor is located within said first endplate.

6. The prosthesis of claim 3, wherein said prosthesis comprises two of said sensors.

7. The prosthesis of claim 3, wherein said prosthesis comprises two of said sensors that are located one on each side of an anterior-posterior centerline of said prosthesis.

8. The prosthesis of claim 3, wherein said prosthesis comprises two of said sensors that are Located at locations which are symmetric with respect to an anterior-posterior centerline of said prosthesis.

9. The prosthesis of claim 3, wherein said prosthesis comprises three of said sensors.

10. The prosthesis of claim 3, wherein said triangle is substantially an isosceles triangle.

11. The prosthesis of claim 3, wherein one of said sensors is located substantially on an anterior-posterior centerline of said prosthesis and two other of said sensors are located one on each side of said anterior-posterior centerline at locations which are symmetric with respect to said anterior-posterior centerline.

12. The prosthesis of claim 3, wherein said sensor is selected from the group consisting of a strain gauge and a piezoelectric sensor.

13. The prosthesis of claim 3, wherein said sensor measures a force exerted by a member that bears at least a portion of any load that is applied to said prosthesis.

14. The prosthesis of claim 3, wherein said sensor measures a force exerted on a member that bears load only when a first component of said prosthesis is touched by a second component of said prosthesis.

15. A spinal disc prosthesis, comprising:

a first endplate and a second endplate, each of said first endplate and said second endplate having a respective bone-contacting surface for attaching to respective vertebrae and a respective non-bone-contacting surface opposite said respective bone-contacting surface;

a polymeric member interposed between and adhered to said first and second endplates;

a first non-deforming component connected to said first endplate; and

a first flat sensor configured to only measure a force that is experienced by said first non-deforming component after a predetermined relative displacement of said first endplate and said second endplate has been reached.

16. The spinal disc prosthesis of claim 15, further comprising a second fiat sensor, wherein said second flat sensor is configured to measure a force exerted by a member that bears at least a portion of any load that is applied to said prosthesis.

17. A spinal disc prosthesis, comprising:

a first endplate and a second endplate each attachable to respective vertebrae;

at least one member suitable to transmit force between said first and second endplates under at least some conditions; and

at least three force sensors associated with one of said endplates and located at locations that form vertices of a triangle,

wherein a first one of said sensors is located substantially on a plane of symmetry of said prosthesis and two other of said sensors are located one on each side of said plane of symmetry, and wherein said three sensors are non-collinear with each other.

18. A spinal disc prosthesis, comprising:

a first endplate and a second endplate each suitable to attach to respective vertebrae; and

a polymeric member interposed between and adhered to said first and second endplates, wherein said polymeric member has an annular shape having an empty central region defining an interior of said polymeric member,

wherein said first endplate comprises a hermetically sealed cavity,

wherein said hermetically sealed cavity comprises a short region having a short region boundary, and a tall region having a tall region boundary,

wherein a portion of said short region boundary of said hermetically sealed cavity is adhered to said polymeric member,

wherein at least a portion of said tall region of said hermetically sealed cavity partially occupies said empty central region of said polymeric member,

further comprising a sensor located in said short portion of said hermetically sealed cavity and

further comprising electronics located in said tall portion of said hermetically sealed cavity.

19. A spinal disc prosthesis, comprising:

a first endplate and a second endplate each suitable to attach to respective vertebrae; and

a polymeric member interposed between and adhered to said first and second endplates, wherein said polymeric member has an annular shape having an empty central region defining an interior of said polymeric member,

wherein said first endplate comprises a hermetically sealed cavity,

wherein said hermetically sealed cavity comprises a short region having a short region boundary and a tall region having a tall region boundary,

wherein a portion of said short region boundary of said hermetically sealed cavity is adhered to said polymeric member,

wherein at least a portion of said tall region of said hermetically sealed cavity partially occupies said empty central region of said polymeric member,

wherein at unloaded conditions said tall region of said hermetically sealed cavity does not contact said second endplate, but if said first endplate and said second endplate are sufficiently close to each other, said tall region of said hermetically sealed cavity contacts said second endplate and receives load from said second endplate.

20. A spinal disc prosthesis, comprising:

a first endplate and a second endplate each suitable to attach to respective vertebrae,

wherein said first endplate comprises a component capable of receiving force exerted by said second endplate or a member connected to said second endplate, said first component further comprising an enclosure;

wherein said first endplate comprises a first layer and a second layer separate from said first layer and facing said first layer;

wherein said first endplate further comprises at least one force sensor, wherein said at least one force sensor is hermetically enclosed within said enclosure; and

wherein, when assembled, said first layer, said at least one force sensor, and said second layer are encompassed within a first thickness that is no larger than a thickness of said first endplate; and

wherein said first thickness is dimensioned parallel to a longitudinal axis of said prosthesis when viewing said prosthesis from an angle normal to said longitudinal axis.

21. The spinal disc prosthesis of claim 20, wherein said enclosure comprises a first flat surface and a second flat surface opposed to said first flat surface, at least a portion of said first flat surface being adhered to said polymeric member, and said second flat surface being a continuous substantially flat uninterrupted surface substantially parallel to said portion of said first flat surface that is adhered to said polymeric member.

22. A spinal disc prosthesis, comprising:

a first endplate and a second endplate each suitable to attach to respective vertebrae;

wherein said first endplate comprises a first layer and a second layer, at least part of said second layer being substantially parallel to said first layer, and a flat region between said first layer and said second layer, said first layer and said second layer being joined to each other at an outer edge;

a polymeric member interposed between and adhered to said second endplate and to said first layer of said first endplate; and

a sensor, positioned suitably to measure a force exerted by said polymeric member on said first endplate in a vicinity of said sensor, wherein said sensor has a flat shape aligned substantially parallel to said first layer;

wherein said first layer has a first surface in contact with said polymeric member and a second surface opposite said first surface, said sensor being in contact with said second surface.

23. The prosthesis of claim 22, wherein said sensor is located inside said first endplate.

24. The prosthesis of claim 22, further comprising a metal layer between said sensor and said polymeric member.

25. A spinal disc prosthesis, comprising:

a first endplate and a second endplate each suitable to attach to respective vertebrae;

at least one member suitable to transmit force between said first and second endplates under at least some conditions; and

wherein at least one of said endplates has a kidney-bean shape having a concavity, a convexity opposed to said concavity, and a first lobe and a second lobe, said first lobe and said second lobe being opposed to each other, and

wherein a first force transducer is located at least partially within said convexity and a second force transducer is located at least partially within said first lobe and a third force transducer is located at least partially within said second lobe;

wherein a first linear axis extends between said second and third force transducers, and a second linear axis bisects and is normal to said first axis;

said first force transducer is positioned on or at a first distance from said second axis, and said second and third force transducers are positioned at a second distance from and on either side of said second axis;

wherein said second distance is greater than said first distance.

26. The spinal disc prosthesis of claim 25, wherein said prosthesis has a plane of symmetry passing through said concavity and said convexity, and said first force transducer is located closer to said convexity than are said second force transducer and said third force transducer.