Posterior stabilization systems and methods

Abstract

Various methods and devices for repairing and / or restoring function to a damaged, injured, diseased, or otherwise unhealthy facet joint, lamina, posterior ligament, and / or other features of a patient's spinal column are provided. In an exemplary embodiment, the methods and devices are effective to mimic the natural function of the posterior elements, preferably without necessarily mimicking the anatomy, by allowing a high degree of flexibility between two adjacent vertebrae when the vertebrae are moved within a first range of motion, and by controlling movement of the adjacent vertebrae within a second range of motion beyond the first range of motion.

Description

FIELD OF THE INVENTION [0001] The present invention relates to spinal instrumentation, and in particular to various devices that are adapted to mimic the natural function of the structural posterior elements. BACKGROUND OF THE INVENTION [0002] The vertebrae in a patient's spinal column are linked to one another by the disc and the facet joints, which control movement of the vertebrae relative to one another. Each vertebra has a pair of articulating surfaces located on the left side, and a pair of articulating surfaces located on the right side, and each pair includes a superior articular surface, which faces upward, and an inferior articular surface, which faces downward. Together the superior and inferior articular surfaces of adjacent vertebra form a facet joint. Facet joints are synovial joints, which means that each joint is surrounded by a capsule of connective tissue and produces a fluid to nourish and lubricate the joint. The joint surfaces are coated with cartilage allowing ...

AI Technical Summary

Benefits of technology

[0010] The present invention also provides methods for replacing and / or stabilizing the posterior elements in adjacent vertebrae. In one embodiment, the method can include the steps of coupling at least one flexible member to two adjacent vertebrae with at least one connector such that the at least one connector is slidably and / or rotatably movable relative to the at least one flexible member, preferably without substantially deforming the flexible member, when the vertebrae are moved within a first range of motion, and such that the at least one connector is effective to stretch and / or deform the at least one flexible member when the vertebrae are moved within a second range of motion beyond the first range of motion. Preferably, the step of coupling at least flexible member to two adjacent vertebrae with at least one connector comprises coupling a superior connector to a superior vertebra, and coupling an inferior connector to an inferior vertebra. The superior connector and the inferior connector can extend through first and second flexible members. In one embodiment, the superior and inferior connectors can be coupled to the superior and inferior vertebrae, respectively, by implanting first and second spinal anchors in each of the superior and inferior vertebra and locking the superior and inferior connectors to the spinal anchors.

Problems solved by technology

Subsequent surgery may also be required after a laminectomy, as a laminectomy predisposes the patient to instability and may lead to post-laminectomy kyphosis (abnormal forward curvature of the spine), pain, and neurological dysfunction.

As a result, additional stress may be applied to the adjoining levels, thereby potentially leading to further damage.

Capping techniques, however, are limited in use as they will not remove the source of the pain in osteoarthritic joints.

Caps are also disadvantageous as they must be available in a variety of sizes and shapes to accommodate the wide variability in the anatomical morphology of the facets.

Caps also have a tendency to loosen over time, potentially resulting in additional damage to the joint and / or the bone support structure containing the cap.

While these techniques can be effective in replacing the bony elements, they do not specify a means to replace the function of the soft tissues and more specifically a means to mimic the load deformation curve of the natural spine.

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