Systems and methods for spinal stabilization with flexible elements
Systems and methods are provided for spinal stabilization with flexible elements and other elements engaged to the vertebrae. Also provided are instruments and methods for insertion of the flexible stabilization elements and other elements and for reduction of displacement between adjacent vertebrae in a minimally invasive surgical approach.
1. A kit for spinal stabilization, comprising a plurality of connecting elements, each of said plurality of connecting elements extending along a longitudinal axis and including:
a rigid first end portion;
a rigid second end portion;
a flexible intermediate portion positioned between the first and second end portions; and
a coupling member extending through the intermediate portion and into the first and second end portions, the coupling member including a first end fixed to one of the first and second end portions and a second end axially moveable in the other of the first and second end portions to allow the first and second end portions to move toward one another, the second end of the coupling member including a stop member to limit movement of the first and second end portions away from one another,
wherein each flexible intermediate portion is provided with a stiffness that varies from one connecting element to another.
2. The kit of claim 1 , wherein said varying stiffness is provided by intermediate portions comprised of elastomers with differing hardness.
3. The kit of claim 1 , wherein said varying stiffness is provided by intermediate portions with differing lengths along the connecting element.
4. The kit of claim 1 , wherein said varying stiffness is provided by intermediate portions with differing cross-sectional areas transverse to a longitudinal axis of the connecting element.
5. The kit of claim 4 , wherein said differing cross-sectional areas are provided by varying at least one of a size and a number of a plurality of bores extending along said intermediate portion.
6. The kit of claim 4 , wherein said differing cross-sectional areas are provided by varying at least one of a size and number of bores extending in said intermediate portion transversely to the longitudinal axis.
7. The kit of claim 1 , wherein said connecting elements each include a coupling member extending through said intermediate portion and engaged to said first and second end portions.
8. The kit of claim 7 , wherein said varying stiffness is provided by differing tension pre-loads on said coupling members.
9. The kit of claim 8 , wherein said varying stiffness is provided by differing diameters of said coupling members.
10. The kit of claim 1 , wherein the coupling member is selected from the group consisting of a rod, a wire, a tether, a suture and a cord and first end portion includes a first passage, the second end portion includes a second passage, and the intermediate portion includes an intermediate passage aligned with the first and second passages, the coupling member being received in the passages, the stop member being received in an enlarged portion of the second passage.