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Multi-walled placeholderRelated Patent Categories: Prosthesis (i.e., Artificial Body Members), Parts Thereof, Or Aids And Accessories Therefor, Implantable Prosthesis, BoneMulti-walled placeholder description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070179610, Multi-walled placeholder. Brief Patent Description - Full Patent Description - Patent Application Claims
RELATED APPLICATIONS [0001] The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/753,854, filed Dec. 23, 2005, and the benefit of U.S. Provisional Patent Application Ser. No. 60/808,028, filed, May 23, 2006, the disclosures of which are incorporated herein by reference. BACKGROUND [0002] The present invention refers to a placeholder for implantation into a human or animal body, especially as a placeholder for vertebrae or vertebral discs, a method for manufacturing such a placeholder, and a modular system for such a placeholder. [0003] Placeholders, especially for vertebrae or vertebral discs are known. For example, DE 19504867 C1 discloses a placeholder in the shape of a cylindrical-tubular body with a plurality of rhombic or diamond-shaped openings that are arranged in rows and columns. At the ends of the cylindrical tube are provided projecting serrations and recesses in correspondence with the rhombi that serve for engaging with adjacent vertebrae or adjacent tissue. The diamond-shaped openings facilitate in-growth of the tissue into the implant, such that the latter may knit well with the body. [0004] Moreover, an implant is known from US 2005/0015154 which has a scaffold-like structure in which the latticework extends over the full body or through the entire body of the implant. Such integral latticework structures are intended for use especially in replacement implants for joints, such as hips, knee joints, shoulder joints and the like. However, such integral latticework structures are difficult to manufacture and have to be adjusted and manufactured individually to suit every application case. [0005] DE 101 38 079 A1 discloses a placeholder of adjustable axial length in which two sleeve-like parts are arranged adjustably inside one another, more precisely via a lever arrangement over which the parts are connected. Although this device facilitates very precise length adjustment, the lever arrangement is complicated to manufacture. [0006] DE 198 04 765 C2 discloses a placeholder for insertion between two vertebrae with an adjustable axial length. The total length is adjusted by moving an external tube relative to an internal tube. The length adjustment proceeds stepwise by means of catches. [0007] DE 697 19 431 T2 describes a longitudinally adjustable vertebral disc placeholder in which two sleeve bodies arranged telescopically inside one another are adjusted relative to each other and are lockable via screw arrangements. However, this arrangement does not uniformly distribute the load across the screw connections and does not effectively allow in-growth by the surrounding tissue because of the close arrangement of the sleeve bodies. [0008] US 2003/0078660 discloses an implant that may be used as a placeholder in which the implant has a sleeve-like body that is corrugated. This corrugated body may in turn be arranged inside a further sleeve body. However, the corrugated form of the one implant part again makes for complicated manufacture. [0009] EP 09 047 51 A1 describes a tubular support body for vertebrae having two cages guided in one another which may be connected to each other by a projecting stud on the jacket surface of the one cage and axial feed channels in the jacket of the other cage. With this arrangement, facilitating of latching positions at different depths is provided. However, the support body is limited in variability by the feed channels. [0010] Based on the above, there is a need for an implant which is easy to manufacture and versatile in use, can provide load dissipation, allows in-growth into human or animal tissue, and is suitable for use as placeholder in the spine, that is, for vertebral discs and vertebrae, but also for tubular bones of the upper and lower extremities. SUMMARY [0011] According to one aspect of the present invention, several tubular bodies, namely a first tubular body and at least a second tubular body, are provided at least partially one inside the other, such that a multi-wall placeholder is formed which not only provides load-absorbing properties but also is suitable for allowing in-growth of adjacent tissue. The cross-sectional shapes of the first and the second bodies in a cross-sectional plane transverse to the longitudinal axis of the placeholder can be different. In particular, the second body arranged in the first body can have a simple or basic geometric shape, namely, a shape which is easy to manufacture. Such shapes include cylindrical or cuboid shapes with round, oval, rectangular or triangular cross-sections. In addition, a shape having a constant cross-section along its length may be used. Such simple geometrical basic shapes for the first and second bodies may be used to generate suitable mechanical properties, yet are affordable and easy to manufacture. [0012] The multi-wall placeholder described herein also provides a large contact surface with the bone at the front face of the placeholder. In addition, with a preassembled multi-wall placeholder, a better adjustment to the bone is possible. Consequently, subsidence of the placeholder may be considerably reduced, if not completely prevented. This can be important for weak osteoporotic vertebrae. The placeholder according to the present invention may also include a plurality of second tubular bodies nested inside each other, all of which are at least partially disposed in the first tubular body. [0013] In one embodiment, the first body may have a circular cross-sectional shape, while the second body or bodies may have a triangular, square, hexagonal, octagonal or generally polygonal, oval or kidney cross-sectional shape. [0014] In a further embodiment, the first tubular body, i.e., the external body may have a cross-sectional shape other than that of a circle, such as an oval or kidney cross-sectional shape, in which case the second body may have a correspondingly adjusted different cross-sectional shape, as described above or a similar shape. [0015] According to another aspect of the present invention, which is also applicable to all disclosed aspects of the invention, several second bodies may be arranged alongside each other in the first body. Accordingly, this arrangement can also achieve mechanical stability and/or ease of in-growth by the surrounding tissue into the placeholder. In addition, the wall thicknesses of the individual components, i.e. of the tubular bodies, may be kept small so as to facilitate in-growth of the tissue into the tubular bodies and thus into the implant. [0016] By providing several second bodies in the first body, e.g., two or three second bodies, the wall thickness of the individual tubular bodies can be reduced, while the overall loading capacity can be improved. The arrangement of two, three or several second bodies in the first body is applicable to all disclosed aspects of the invention. [0017] The second bodies can be spaced from each other and/or from the first body to promote in-growth of body tissue between the bodies. This also allows for more precise adjustment relative to the adjacent bone or to a placeholder end plate. Moreover, the spacing between the bodies will result in better in-growth and a more homogeneous distribution of the load across the cross-section of the implant. [0018] In the case of the arrangement of several second bodies in the first body, the arrangement of the second bodies may be such that their longitudinal axes are offset parallel to the tubular longitudinal axis of the first body. The result of this is that greater stability can be obtained for certain instances of mechanical loading. For example, the offset arrangement of the bodies may lead to greater stability in the case of flexural stress. [0019] Overall, the cross-sectional shape of the first and/or second bodies may assume diverse shapes, namely circles, triangles, oblongs, rectangles, squares, diamonds, (rhombi), polygons, hexagons, octagons, especially with rounded comers, ovals, kidney shapes or any free-form shapes. However, the shape can be restricted to certain basic shapes as this simplifies manufacturability. Among the basic shapes are especially circles, triangles, oblongs, rectangles, squares, diamonds, hexagons, all angular shapes including those with rounded comers and ovals and kidney shapes. [0020] According to a further aspect of the present invention, which is also applicable to all disclosed aspects of the invention, the second body or bodies can be accommodated in the first body by means of a press fit or force fit. For example, the outer dimension of the second body or bodies is larger than the inner dimension of the first body. This results in an elastic deformation of the bodies in the case of a force fit or an additional plastic deformation in the case of press fit. Alternatively, a connecting element or retaining element between the bodies can be a force fit or press fit. [0021] The press fit or force fit may thus be directly affected by contact between the first body and the second body/bodies or by the connecting elements. Continue reading about Multi-walled placeholder... Full patent description for Multi-walled placeholder Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Multi-walled placeholder 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 Multi-walled placeholder or other areas of interest. ### Previous Patent Application: System and method for articular surface repair Next Patent Application: Methods and devices for replacement of intervertebral discs Industry Class: Prosthesis (i.e., artificial body members), parts thereof, or aids and accessories therefor ### FreshPatents.com Support Thank you for viewing the Multi-walled placeholder patent info. 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