Non-linear artificial ligament system
Various methods and devices for ligament replacement in the human body, and in particular, the spine are provided. In an exemplary embodiment, a ligament replacement system is provided that has an artificial ligament configured in the form of a closed loop. The artificial ligament is adapted to be coupled between the ligament seating regions of first and second connection members in a connection geometry that results in the artificial ligament having a large motion with a non-linear relationship between the force and displacement, similar to that of a natural ligament.
1. A system for stabilizing adjacent bone segments, comprising:
at least one artificial ligament configured to couple at least two connection members;
a first connection member having first and second arms configured to be coupled to a first bone segment and having a first central element extending between the first and second arms with at least one first ligament seating region formed around the first central element for receiving the at least one ligament, the at least one first ligament seating region having at least one ligament contact region with a first surface area; and
a second connection member having first and second arms configured to be coupled to a second bone segment and having a second central element positioned in contact with the first central element and extending between the first and second arms with at least one second ligament seating region formed around the second central element, the at least one second ligament seating region having at least two ligament contact regions with a second surface area,
wherein the at least one ligament is slidably disposed within the first and second ligament seating regions to contact the ligament contact regions of the first and second connection members such that the artificial ligament exhibits a non-linear force displacement relationship.
2. The system of claim 1 , wherein the first surface area is less than the second surface area such that the at least two ligament contact regions are located at opposed edges of the ligament seating region of the second connection member.
3. The system of claim 1 , wherein the ligament is configured in the form of a closed loop.
4. The system of claim 1 , wherein the bone segments are adjacent vertebrae.
5. The system of claim 1 , wherein the at least one artificial ligament is a polymer fiber.
6. The system of claim 5 , wherein the polymer is polyethylene, polyester, polypropylene, polyaramide, or any combination of thereof.
7. The system of claim 1 , wherein the at least one artificial ligament has a stretch that is less than 5%.
8. The system of claim 1 , wherein the at least one artificial ligament has a tensile strength that is greater than about 100N.
9. The system of claim 1 , wherein the at least one artificial ligament has opposed first and second ends, and an eyelet formed on each end, such that the closed loop can be formed by inserting a fastener through the eyelets.
10. The system of claim 1 , wherein the first and second connection members are adapted to articulate relative to one another.
11. The system of claim 1 , wherein the first and second connection members are in the form of substantially V-shaped connectors adapted to be positioned on a posterior surface of a first and second vertebrae.
12. The system of claim 1 , wherein the ligament seating region is a groove that is adapted to slidably receive the at least one artificial ligament.
13. The system of claim 1 , wherein the ligament seating region is a post that is adapted to slidably receive the at least one artificial ligament.
14. The system of claim 13 , wherein the post has a groove formed therein for receiving the at least one artificial ligament.
15. The system of claim 13 , wherein the post has a stop formed at an end thereof for receiving the at least one artificial ligament.
16. The system of claim 1 , wherein the ligament contact region is a pulley.
17. The system of claim 1 , wherein the ligament contact region is a pivot point.
18. The system of claim 1 , further comprising at least three ligament contact regions.