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Spinal prosthesis and facet joint prosthesisRelated Patent Categories: Prosthesis (i.e., Artificial Body Members), Parts Thereof, Or Aids And Accessories Therefor, Implantable Prosthesis, Bone, Spine BoneSpinal prosthesis and facet joint prosthesis description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060089717, Spinal prosthesis and facet joint prosthesis. Brief Patent Description - Full Patent Description - Patent Application Claims
REFERENCE TO PENDING APPLICATIONS [0001] This application is a continuation-in-part of U.S. application Ser. No. 10/970,091, filed on Oct. 21, 2004 and entitled POSTERIOR SPINAL ARTHROPLASTY--DEVELOPMENT OF A NEW POSTERIORLY INSERTED ARTIFICIAL DISC, A NEW ANTERIORLY INSERTED ARTIFICIAL DISC AND AN ARTIFICIAL FACET JOINT, which is pending. FIELD OF 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 symptoms. [0004] Although the majority of patients have minor sprains or strains which are self limiting, a significant number of patients go on to develop severe chronic mechanical lower back pain which is caused by inflammatory changes in the lumbar disc associated with degeneration. [0005] Another group of patients with degenerative spine disease go on to develop degenerative spondylolisthesis and spinal stenosis. This is a narrowing of the spinal canal caused primarily by degenerative changes in the facet joint, combined with a loss of normal disc height and buckling of the ligamentum flavum. [0006] Degeneration occurs in a spinal segment. The spinal segment consists of the lumbar disc anteriorly and two facet joints posteriorly. This is therefore called a three joint complex. Degenerative changes in the disc can lead to changes in the facet joint and vice versa. In patients with significant lumbar disc degeneration, the facet joints are also usually degenerate. [0007] Pain occurs from all components of the three joint complex, including the facet joints and the disc. The facet joint is in fact a synovial joint and suffers from the problems that are known to affect other synovial joints in the body like the hip and the knee. The facet joint particularly contributes to degenerate spondylolisthesis and commonly occurs at levels where the facet joints are sagittally orientated, for example at the L4/5 level. [0008] After failing all the conservative treatments available, a minority of patients with back pain or leg pain will go on to require surgical intervention. For patients with predominantly lower back pain who have a degenerative lumbar disc, some surgeon's consider the solution lies in removing the pain generator which is the disc and restoring normal loading across the disc by doing an inter-body stabilisation procedure. [0009] The two types of inter-body stabilisation procedure currently available are an artificial disc replacement performed anteriorly and inter-body fusions performed anteriorly and/or posteriorly. These inter-body stabilisation procedures are often combined with decompression of the spinal canal and the nerve roots if there is nerve root impingement. [0010] As far as inter-body fusions are concerned, there are two basic strategies that surgeons adopt. The first is to perform an anterior inter-body fusion combined with posterior stabilisation externally of the spinal canal. Anterior inter-body fusion on its own is still questioned because it does not provide a posterior tension band. An alternative strategy is a posterior lumbar inter-body fusion, where the entire inter-body fusion procedure is performed from behind and it is combined with neural decompression as well as removal of the degenerative facet joints. Posterior lumbar inter-body fusion also provides a posterior tension band. This strategy therefore deals with all three joint components which can generate possible pain at the disc level, including the lumbar disc, the neural structures and the facet joints. [0011] When it comes to lumbar disc arthroplasty procedures, these are performed via an anterior lumbar approach. The disc is removed and an artificial lumbar disc is inserted into the space. This removes the pain generator and allows normal loading across the disc, as well as allowing some movement at this level. The advantage of this is to reduce the strains on the disc above and therefore reduce the chances of adjacent segment degeneration. Several studies have shown that adjacent segment degeneration can occur above a fused segment because of the increased loads being transmitted to this level. [0012] One of the disadvantages of anterior lumbar arthroplasty is that the facet joints at this level continue to move and also continue to act as a pain generator. In addition, if there is any neural impingement, these symptoms can continue. The other disadvantage of anterior lumbar arthroplasty is that the majority of spine surgeons are not familiar with the anterior approach, and although complications are uncommon, they can be life and limb threatening when they do occur. [0013] There is therefore a concern among researchers and the surgical community, that long term results of anterior lumbar disc arthroplasty may be compromised by progressive degeneration of the facet joint at the same level. In addition, after lumbar disc arthroplasty, several patients continue to complain of facet joint pain because of increased loads being placed on the facet joint as a result of the surgical procedure. [0014] At present there is no posterior lumbar arthroplasty procedure available. It is therefore an aim of the present invention to provide an artificial lumbar disc that can be inserted posteriorly, thereby delivering the advantages of approaching the spine posteriorly and removing the disadvantages associated with approaching the spine anteriorly. [0015] It is a further aim of the present invention to provide a facet joint replacement prosthesis. [0016] It is a yet further aim of the present invention to provide a lumbar prosthetic system that deals with the painful disc, the neural impingement and the painful facet joints by providing a combination of a lumbar disc prosthesis and a facet joint prosthesis as a single unit. [0017] It is a further aim of the present invention to provide an artifical disc prosthesis that utilises one or more of the features and advantages provided by the posteriorly inserted disc but which can be inserted anteriorly. [0018] It is a yet further aim of the present invention to provide a prosthetic system that deals with the painful disc, the neural impingement and the painful facet joints by providing a combination of a disc prosthesis and a facet joint prosthesis as a single system that works together. SUMMARY OF THE INVENTION [0019] According to a first aspect of the present invention there is provided a disc prosthesis, said disc prosthesis including a pair of disc members, the first member of said disc pair having a vertebral endplate contact surface and a recessed portion on an opposing surface thereof, the second member of said disc pair having a vertebral endplate contact surface and a protruding portion on an opposing surface thereof, the protruding portion of the second member engaging with the recessed portion of the first member in use, and wherein the inner or opposing surface of at least the first disc member is provided with at least three sections; a middle section and at least two end sections, the recessed portion being provided in the middle section and the thickness or depth of the middle section being less compared to the two end sections thereof. [0020] In one embodiment the end sections, typically located adjacent the anterior and posterior edges of the prosthesis are substantially surfaces which are planar in form. Thus, the planar ends sections are different in form to the curved middle recessed section. Continue reading about Spinal prosthesis and facet joint prosthesis... Full patent description for Spinal prosthesis and facet joint prosthesis Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Spinal prosthesis and facet joint prosthesis 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. 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