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Spacerless artificial disc replacementsRelated Patent Categories: Prosthesis (i.e., Artificial Body Members), Parts Thereof, Or Aids And Accessories Therefor, Implantable Prosthesis, Bone, Spine Bone, Having Opposed Bone-plates Which Moves Relative To One AnotherSpacerless artificial disc replacements description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20050267582, Spacerless artificial disc replacements. Brief Patent Description - Full Patent Description - Patent Application Claims
REFERENCE TO RELATED APPLICATION [0001] This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 60/372,520, filed Apr. 12, 2002 and this application is a continuation of U.S. application Ser. No. 10/413,028, filed on Apr. 14, 2003, the disclosures of which are incorporated herein by reference. FIELD OF THE INVENTION [0002] This invention relates generally to artificial disc replacements (ADRs) and, more particularly, to devices that operate without softer spacer materials such as polyethylene. BACKGROUND OF THE INVENTION [0003] Polyethylene spacers are common in some artificial joint situations, including total knee replacements (TKRs). Polyethylene spacers are also used between metal plates in many artificial disc replacement (ADR) designs. [0004] Complications arising from poly debris are well documented, however, including fracture of the spacer once it becomes too thin, absorptions and migration of poly particles throughout the body, and loosening of the bone metal junction as a reaction of the poly debris. [0005] Metal-on-metal and ceramic-on-metal surfaces have much lower wear characteristics. In fact, metal-on-metal surfaces demonstrate 400 times less wear than polyethylene on metal surfaces. [0006] While there have been attempts to limit the use of the poly in ADR designs, all existing approaches constitute call-and-socket configurations which do not inherently limit axial rotation. Instead, axial rotation is limited through the use of multiple ball-and-socket joints or an elongated ball-and-socket joint, which complicates the design. SUMMARY OF THE INVENTION [0007] The present invention replaces polyethylene artificial disc replacement (ADR) spacers with harder, more wear resistant materials. In the preferred embodiments, an ADR according to the invention includes opposing saddle-shaped components to facilitate more normal spinal flexion, extension, and lateral bending. Preferably, the ADR allows at least 10 degrees of movement on the flexion to extension direction and at least 5 degrees of movement in the lateral bending direction. The saddle-shaped articulating surfaces also limit axial rotation, thereby protecting the facet joints and the annulus fibrosis (AF). [0008] According to the invention, either or both the superior and inferior components are made of a hard material such as chrome cobalt, titanium, or a ceramic including alumina, zirconia, or calcium phosphate. The articulating surfaces of the ADR are also preferably highly polished to reduce friction between the components. Metals, alloys or other materials with shape-memory characteristics may also prove beneficial. [0009] The vertebral surfaces of the components may be treated to promote bone ingrowth. For example, the vertebral surfaces of the components may have plasma spray or beads. Alternatively, one or both components may be cemented to the vertebrae. The vertebra-facing surfaces may also include projections such as keels that fit into the vertebrae. In embodiments adapted for cementation, one of the components could be made of polyethylene or other softer material. BRIEF DESCRIPTION OF THE DRAWINGS [0010] FIG. 1A is an anterior view of an ADR according to the invention; [0011] FIG. 1B is a lateral view of the ADR of FIG. 1; [0012] FIG. 1C is an oblique view of the ADR of FIG. 1; [0013] FIG. 2A is a view of the anterior aspect of an alternative embodiment of the ADR; [0014] FIG. 2B is a view of the lateral aspect of an alternative embodiment of the ADR shown in FIG. 2B; [0015] FIG. 3A is a view of the anterior aspect of an alternative, less constrained, embodiment of the saddle-shaped ADR shown in a fully flexed position; [0016] FIG. 3B is a view of the lateral aspect of the embodiment of the ADR shown in FIG. 3A; [0017] FIG. 4A is a view of the lateral aspect of another embodiment of a saddle-shaped ADR; [0018] FIG. 4B is a view of the anterior aspect of the embodiment of the ADR shown in FIG. 4A in a fully flexed position; [0019] FIG. 4C is a view of the anterior aspect of an alternative embodiment; Continue reading about Spacerless artificial disc replacements... Full patent description for Spacerless artificial disc replacements Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Spacerless artificial disc replacements patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Spacerless artificial disc replacements or other areas of interest. ### Previous Patent Application: Intervertebral implant Next Patent Application: Radiovisible hydrogel intervertebral disc nucleus Industry Class: Prosthesis (i.e., artificial body members), parts thereof, or aids and accessories therefor ### FreshPatents.com Support Thank you for viewing the Spacerless artificial disc replacements patent info. 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