Two-component artificial disc replacements
View Patent ↗Artificial disc replacements (ADRs) and total disc replacements (TDRs) are based upon two, directly articulating components, resulting in a restricted-motion system that better approximates more normal spinal flexion, extension, and lateral bending. Both components are preferably made of a hard material and are highly polished to reduce friction.
1. An artificial disc replacement (ADR) having an anterior-to-posterior orientation and a lateral orientation, the ADR comprising:
first and second components having first and second bone-contacting surfaces adapted to contact first and second adjacent vertebrae, first and second articulating surfaces positioned at an anterior location of the ADR, and first and second stop surfaces positioned at a posterior location of the ADR, wherein the first articulating surface has a concave surface and the second articulating surface has an opposing convex surface; and
wherein, as a result of engagement between the first and second stop surfaces, extension of the first and second vertebrae relative to one another is restricted to relive pressure borne by opposing facets of the first and second vertebrae.
2. The ADR according to claim 1 , wherein the first and second stop surfaces are spaced apart when the first and second components of the ADR are placed in a flexion orientation, and the first and second stop surfaces are engaged when the first and second components of the ADR are placed in an extension orientation.
3. The ADR according to claim 1 , wherein the ADR allows flexion between the first and second vertebrae, but restricts extension to relive pressure borne by the facets.
4. The ADR according to claim 1 , wherein a first distance between the first and second bone-contacting surfaces at the anterior location is greater than a second distance between the first and second bone-contacting surfaces at the posterior location.
5. The ADR according to claim 1 , wherein the first and second stop surfaces are arranged to limit lateral bending by way of engagement between the stop surfaces upon lateral bending of the first and second components.
6. The ADR according to claim 1 , wherein the first and second articulating surfaces form a spoon-on-spoon configuration to limit rotation and translocation of the first and second components.
7. The ADR according to claim 1 , further comprising apertures in the first and second components for receiving respective fixation members.
8. The ADR according to claim 7 , wherein the apertures are positioned on flanges extending from the first and second components, the flanges being adapted to engage an anterior portion of the first and second vertebrae.
9. The ADR according to claim 1 , wherein at least one of the first and second components includes an extension projecting outward from the component to prevent trapping of soft tissue during movement of the first and second components relative to one another.
10. The ADR according to claim 1 , wherein at least one check rein is attached to the first and second components to restrict motion of the first and second components.
11. The ADR according to claim 10 , wherein the at least one check rein is an anterior check rein, a lateral check rein, or a cross-coupled check rein used to prevent translation.
12. An artificial disc replacement (ADR) comprising:
first and second components having first and second bone-contacting surfaces adapted to contact first and second adjacent vertebrae, first and second articulating surfaces positioned at a first location offset from a center of the ADR in an anterior direction, and first and second stop surfaces positioned at a second location offset from the center of the ADR in a posterior direction, wherein the first articulating surface has a concave surface and the second articulating surface has an opposing convex surface; and
wherein, as a result of engagement between the first and second stop surfaces, extension of the first and second vertebrae relative to one another is restricted to relive pressure borne by opposing facets of the first and second vertebrae, the articulating surfaces allowing flexion between the first and second vertebrae but restricting extension via the first and second stop surfaces.
13. The ADR according to claim 12 , wherein a spacing between the first and second bone-contacting surfaces is sufficient to distract a disc space between the first and second vertebrae from a first preoperative distance to a second greater distance to relieve the pressure borne by the facets.
14. The ADR according to claim 12 , wherein the first and second stop surfaces are spaced apart when the first and second components of the ADR are placed in a flexion orientation, and the first and second stop surfaces are engaged when the first and second components of the ADR are placed in an extension orientation.
15. The ADR according to claim 12 , wherein a first distance between the first and second bone-contacting surfaces at the first location is greater than a second distance between the first and second bone-contacting surfaces at the second location.
16. The ADR according to claim 12 , wherein the first and second stop surfaces are arranged to limit lateral bending by way of engagement between the stop surfaces upon lateral bending of the first and second components.
17. The ADR according to claim 12 , wherein the first and second articulating surfaces form a spoon-on-spoon configuration to limit rotation and translocation of the first and second components.
18. The ADR according to claim 12 , further comprising apertures in the first and second components for receiving respective fixation members.
19. The ADR according to claim 18 , wherein the apertures are positioned on flanges extending from the first and second components, the flanges being adapted to contact an anterior portion of the first and second vertebrae.
20. The ADR according to claim 12 , wherein at least one check rein is attached to the first and second components, the at least one check rein being an anterior check rein, a lateral check rein, or a cross-coupled check rein used to prevent translation.