Posterior spinal arthroplasty-development of a new posteriorly inserted artificial disc, a new anteriorly inserted artifical disc and an artificial facet joint

Abstract

A lumbar disc prosthesis is provided including a pair of disc members. The first member of the disc pair has a vertebral disc contact surface and a recessed portion on an opposing surface thereof. The second member of the disc pair has a vertebral disc contact surface and a protruding portion on an opposing surface thereof. The protruding portion of the second member engages with the recessed portion of the first member in use. Each of the first and second disc members are provided with at least three sections; a middle section and two end sections. The recessed and protruding portions are provided in the middle section of the respective disc members and each of the two end sections have a narrowing taper towards the ends of the disc members. The facet joint prosthesis includes a first member for attachment to a first posterior lumbar disc in use and a second member for attachment to a second posterior lumbar disc in use. At least a part of the first member is telescopically mounted in at least a part of the second member in use.

Description

REFERENCE TO PENDING APPLICATIONS [0001] This application is a continuation-in-part of pending U.S. application Ser. No. 11 / 203,259 filed on Aug. 12, 2005, which is a continuation-in-part of pending U.S. Application No. 10 / 970,091 filed on Oct. 21, 2004.FIELD OF THE INVENTION [0002] This invention relates to devices and surgical methods for the treatment of various types of spine pathologies. It deals with the development of an artificial facet joint, and an artificial lumbar disc replacement that is specifically designed to be inserted from a posterior approach to the spine. It also deals with the development of an artificial disc replacement that can be inserted from an anterior approach to the spine. BACKGROUND OF THE INVENTION [0003] Back pain affects 40% of the population. Up to 20% of the population visit their family doctor requesting help with their back problem. Up to 30% of patients continue to complain of significant back pain at one year following the onset of their symp...

AI Technical Summary

Benefits of technology

[0021] The geometry of the middle and end sections of at least the first disc member allows contact to be made between the recessed and protrusion portions of the first and second disc members and for a gap to be formed adjacent the end sections of the disc members when the prosthesis is in a neutral position. When the prosthesis is in extension (i.e. the upper or first disc member moves posteriorly relative to the lower or second disc member), the gap between the end section at the anterior end increases, thereby causing the annulus anteriorly to tighten. Due to the geometry of the planar slopes within the prosthesis, the annulus will tighten not only anteriorly in flexion but laterally as well. This results in a physiological stop to further extension. Similarly in flexion the upper disc member moves anteriorly relative to the lower disc member, resulting in an increased gap posteriorly between the two disc members, and this causes the annulus posteriorly and laterally to tighten, resulting in a physiological stop to further flexion.

[0096] Thus, the present invention overcomes the problems and disadvantages associated with current disc replacement strategies. It has all the benefits associated with posterior lumbar inter-body fusion surgery, but at the same time it allows movement at that level and reduces the strain on adjacent discs and the risks of adjacent segment disc failure. This invention also addresses all three pain generators at the lumbar disc level including the degenerative disc, the impingement of the neural structures, and the facet joint.

Problems solved by technology

This results in a physiological stop to further extension.

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