Patent EP0765644A2 successfully refreshed from Google Patents.
EP0765644A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Hollow bone prosthesis with tailored flexibility
Assignee: DePuy Products Inc
•
Filing: 1996-09-27
•
Granted: —
•
Expires: 2016-09-27
Abstract
Abstract 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.
Inventors
- 👤 Robert E. Sommerich
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 13:39
CPC Classifications
B; B22; B22C; B22C9/00; B22C9/22; B22C9/24; A; A61; A61F; A61F2/00; A61F2/02; A61F2/30; A61F2/30721; A61F2/30734; A61F2/3094; A61F2/30942; A61F2/32; A61F2/36; A61F2/3662; A61F2/30767; A61F2/30771; A61F2/30907; A61F2/367; A61F2002/30001; A61F2002/30003; A61F2002/30004; A61F2002/30014; A61F2002/30316; A61F2002/30317; A61F2002/30324; A61F2002/30329; A61F2002/30451; A61F2002/30535; A61F2002/30593; A61F2002/30604; A61F2002/30616; A61F2002/30795; A61F2002/30805; A61F2002/30957; A61F2002/3678; A61F2002/3694; A61F2220/00; A61F2220/0025; A61F2220/0058; A61F2250/00; A61F2250/0014; A61F2250/0018; A61F2250/0029; A61F2250/0036; B29; B29C; B29C33/00; B29C33/44; B29C33/448; B29C43/00; B29C43/006; B29L; B29L2031/00; B29L2031/753; B29L2031/7532; B33; B33Y; B33Y80/00
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
87 words
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 along the length of the bone, and wherein the stem further is hollow with an interior surface characterized by lack of machine symmetry, said outer and said interior surface producing therebetween a wall thickness of the stem effective to achieve a growth sustaining level of strain transfer to surrounding bone along said contact region.
Claim 2
Dependent Claim
54 words
A bone prosthesis according to claim 1, wherein the stem is a tapered stem with a textured region. to wedge into and promote cancellous bone intergrowth with a femur, and said interior surface has a contour effective to strengthen the textured region while in use strain is transferred along the length of the stem.
Claim 3
Dependent Claim
29 words
A bone prosthesis according to claim 1, wherein the stem has an interior void extending along an axis with a cross dimension of said void that generally decreases distally.
Claim 4
Dependent Claim
12 words
A bone prosthesis according to claim 3, wherein the cross-dimension decreases non-monotonically.
Claim 5
Dependent Claim
13 words
A bone prosthesis according to claim 3, wherein the cross-dimension lacks radially symmetry.
Claim 6
Dependent Claim
36 words
A bone prosthesis according to claim 1, wherein the interior surface has a contour to define a prosthesis wall having a bending stiffness in a proximal region substantially under ten times the bending stiffness of bone.
Claim 7
Dependent Claim
28 words
A bone prosthesis according to claim 2, wherein the inner contour defines a stiffness under about five to seven times normal bone stiffness along substantially its entire length.
Claim 8
Dependent Claim
36 words
A bone prosthesis according to claim 7, wherein the contour provides a thinned wall such that the prosthesis has a stiffness under about three to five times normal bone stiffness below a neck of the prosthesis.
Claim 9
Dependent Claim
38 words
A bone prosthesis according to claim 1, wherein said hollow interior provides a non-uniform wall thickness effective to determine axial stiffness which varies by a factor of less than about five along the length of the stem body.
Claim 10
Dependent Claim
20 words
A bone prosthesis according to claim 1, wherein the wall thickness increases at regions which proximately support an articulation component.
Claim 11
Dependent Claim
78 words
A bone prosthesis having an outer surface and an inner surface, the outer surface having to a taper for fitting into a hollowed bone, and the inner surface bulging with a non-machine symmetry to define a wall thickness that generally varies along the prosthesis such that the prosthesis has stiffness characteristics comparable to those of normal bone and transfers strain to the hollowed bone, while maintaining a level of strength and resistance to breaking greater than such bone.
Claim 12
Dependent Claim
46 words
A bone prosthesis according to claim 11, wherein the inner surface defines a thickened support positioned to support the load of an articulation component, while defining a region of thinned wall proximal thereto and having bending stiffness under 8e 9 mm 4 x N/mm 2 .
Claim 13
Dependent Claim
49 words
A bone prosthesis having a 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 wall thickness providing a stiffness distribution effective to transfer strain along the length of the body.
Claim 14
Independent Claim
97 words
A method of forming a bone prosthesis, such method comprising the steps of forming a mold block having a generally tapered cavity corresponding to a desired size of prosthesis stem forming a plug body of smaller cross-dimension than said tapered cavity fitting the plug body in the cavity of the mold block, casting metal between the plug body and the mold block to form a metal cast prosthesis, and removing the prosthesis from the mold block and the plug body from the prosthesis to achieve a hollow prosthesis having a stiffness comparable to stiffness of normal bone.
Claim 15
Independent Claim
35 words
A method of forming a metal prosthesis, characterized by the step of casting the prosthesis in a mold cavity about a plug insert, such that the prosthesis has a hollow interior shaped as said insert.
Claim 16
Dependent Claim
14 words
The method of claim 15, further including the step of closing said hollow interior.
Claim 17
Dependent Claim
35 words
A bone prosthesis according to claim 1, wherein said interior surface has a contour which varies locally to preferentially strengthen a critical region of said prosthesis while distributing load globally to surrounding bone in use.
Claim 18
Dependent Claim
38 words
A bone prosthesis according to claim 1, wherein the prosthesis has a proximal region and said inner contour produces a structural stiffness at least ten percent less in said proximal region than stiffness of a solid metal prosthesis.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.