Facet joint replacement

Abstract

A prosthesis for the replacement of at least a portion of the bone of a facet located on a mammalian vertebra, comprising: an articulating surface that articulates with another facet; a bone contacting surface that contacts a surface of the vertebra, the articulating surface being connected to the bone contacting surface; and a fixation element that attaches the bone contacting surface to the vertebra, the fixation element being adapted for implantation into an interior bone space of a pedicle of the vertebra; wherein the prosthesis is configured so that no portion of the prosthesis contacts the posterior arch of the vertebra.

Description

REFERENCE TO PENDING PRIOR APPLICATIONS [0001] The present application claims the benefit of: [0002] (i) pending prior U.S. patent application Ser. No. 10 / 421,078, filed Apr. 23, 2003 by E. Marlowe Goble et al. for FACET JOINT REPLACEMENT (Attorney's Docket No. MED-1 CON); and [0003] (ii) pending prior U.S. Provisional Patent Application Ser. No. 60 / 505,199, filed Sep. 23, 2003 by E. Marlowe Goble et al. for FACET JOINT REPLACEMENT (Attorney's Docket No. MED-1 CIP PROV). [0004] The two above-identified documents are hereby incorporated herein by reference.BACKGROUND OF THE INVENTION [0005] 1. Field Of The Invention [0006] The present invention relates to surgical devices and methods to replace a damaged, diseased, or otherwise painful spinal facet joint. [0007] 2. Description Of Related Art [0008] Traumatic, inflammatory, metabolic, and degenerative disorders of the spine can produce debilitating pain that can have severe socioeconomic and psychological effects. One of the most comm...

AI Technical Summary

Benefits of technology

[0100] The present invention has numerous advantages over the prior art. One advantage is that the quality of attachment of the prosthesis is improved. The present invention provides a precise press fit into bones, as opposed to relying on prosthetic surfaces mating with highly complex and variable external surfaces of the vertebra, such as the posterior arch or facet. Another advantage is that the optional porous coating is placed into interior bone spaces where porous coatings have proven to achieve bone ingrowth for excellent long term fixation strength. This ability to achieve bone ingrowth is uncertain for the prior art devices that engage the external bone surfaces of the vertebra. Yet another advantage lies in the removal of the facet bone structure; where the facet bone is involved in the disease pathology or the trauma that compromised the articular or cartilaginous surface of the facet, resection provides a means for ensuring that all pain associated with the disease or trauma is removed.

Problems solved by technology

Traumatic, inflammatory, metabolic, and degenerative disorders of the spine can produce debilitating pain that can have severe socioeconomic and psychological effects.

Furthermore, Khoo and Nagata have shown that spine fusion creates increased stresses and, therefore, accelerated degeneration of adjacent non-fused motion segments.

Additionally, pseudoarthrosis, as a result of an incomplete or ineffective fusion, may reduce or even eliminate the desired pain relief for the patient.

However, the artificial discs proposed to date do not fully address the mechanics of motion of the spinal column.

Like the Fitz design, the Martin prosthesis generally preserves existing bony structures and therefore does not address pathologies that affect the bone of the facets in addition to affecting the associated cartilage.

Since the posterior arch is a very complex and highly variable anatomic surface, it would be very difficult to design a prosthesis that provides reproducible positioning to correctly locate the cartilage-replacing blades for the facet joints.

Images