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US 5,725,586 AGranted
Hollow bone prosthesis with tailored flexibility
AssigneeJohnson & Johnson Professional, Inc.
InventorRobert E. Sommerich
Life of this patent
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AssigneeJohnson & Johnson Professional, Inc.
InventorRobert E. Sommerich
Estimating the term…
A bone prosthesis has a stem with a hollow interior and an external surface that allows wedging contact with surrounding bone while transferring strain at a level comparable to that of natural bone. The stem is cast about an irregular plug body, which is then removed, leaving a wall thickness that satisfies the opposing constraints of high strength and relatively low stiffness. The plug narrows the prosthesis wall thickness in upper regions thereof and strengthens the wall about regions of recessed or discontinuous features, or high load coupling, to assure that the stem has adequate strength in regions of high strain, while effectively coupling strain to surrounding bone. The prosthesis is produced in a range of sizes, and plugs or entire molds for casting the hollow body are readily made and modified by a three-dimensional printing mold fabrication technique.
A bone prosthesis of the type having a stem insertable in a bone for fixation thereto, wherein the stem is a generally elongated spike which provides an outer surface forming a contact region adapted for contacting a length of the bone, and wherein the stem further is hollow with a non-monotonically decreasing interior surface, said outer and said interior surface producing therebetween a wall thickness of the stem, the wall thickness having at least one region of locally increased thickness effective to achieve a growth sustaining level of strain transfer to surrounding bone along said contact region.
A bone prosthesis having an outer surface and an inner surface defining a wall, the outer surface having a taper for fitting into a hollowed bone, and the inner surface defining a profile whereby the thickness of the wall formed between the inner surface and the outer surface generally decreases at least once along the prosthesis such that the prosthesis transfers strain to the hollowed bone after implantation, while maintaining a level of strength and resistance to breaking greater than such bone.
A bone prosthesis having an elongated metal body formed by casting around a plug insert having a shape, such that the metal body has an unfinished interior surface conformal to said shape, and defines, in combination with the outer surface, a wall thickness having at least one region of locally increased thickness providing an axial stiffness distribution effective to transfer strain along a length of the body.
Dependencies are inferred from the claim text.