US4662889A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Knee joint prosthesis
Assignee: Cerasiv GmbH Innovatives Keramik Engineering
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Filing: 1984-04-26
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Granted: 1987-05-05
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Expires: 2004-04-26
Abstract
Abstract A knee joint prosthesis includes a C-shaped femur cap to be fitted onto a resected femur condyle. The C-shaped femur cap is made up of two arch-shaped parts spaced apart and connected by a relatively flat third part. Each of the arch-shaped parts has a different radius. The arch-shaped part with the larger radius has an oblong hole extending in the circumferential direction of the part. A shaft can be placed through the oblong hole from the femur into the tibia. In addition, a tibia cap can be fitted onto the plateau of the tibia.
Inventors
- 👤 Ludwig Zichner
- 👤 Erhard Dorre
- 👤 Peter Prussner
- 👤 Horst von Borries
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 22:59
CPC Classifications
A; A61; A61F; A61F2/00; A61F2/02; A61F2/30; A61F2/38; A61F2/3836; A61F2/384; A61F2/385
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
204 words
An implantable knee joint for connecting the femur with the tibia comprising a femoral cap having a C-shaped cross-section for partial enclosure of the resected femoral condyles and for abutment and support on the tibial plateau, said cap having an inner and outer surface; said outer surface shaped to serve as a sliding surface for a corresponding tibial member and said inner surface being mechanically connectable to said resected condyles, wherein the improvement comprises said cap having two arcuate shaped bearing surfaces separated by an oblong cut-out extending in a circumferential direction about said cap wherein said cut-out is in substantially coincidence with a similar shaped slot formed in said resected condyles; and an axially extending cylindrically substantially disc-shaped sliding member disposed in said slot to directly abut the bony tissues of said resected condyles and said disc-shaped sliding member being coupled to a connecting member, said connecting member being an elongated shaft having a first and second ends wherein said first end is arranged to extend into and mechanically anchor within the tibia and the second end extending out of said tibia through said cut-out into a closely fitted engagement with said disc-shaped sliding member thereby actively connecting the femur with the tibia.
Claim 2
Dependent Claim
204 words
An implantable knee joint for connecting the femur with the tibia comprising a femoral cap having a C-shaped cross-section for partial enclosure of the resected femoral condyles and for abutment and support on the tibial plateau, said cap having an inner and outer surface; said outer surface shaped to serve as a sliding surface for a corresponding tibial member and said inner surface being mechanically connectable to said resected condyles, wherein the improvement comprises said cap having two arcuate shaped bearing surfaces separated by an oblong cut-out extending in a circumferential direction about said cap wherein said cut-out is in substantially coincidence with a similar shaped slot formed in said resected condyles; and an axially extending cylindrically substantially disc-shaped sliding member disposed in said slot to directly abut the bony tissues of said resected condyles and said disc-shaped sliding member being coupled to a connecting member, said connecting member being an elongated shaft having a first and second ends wherein said first end is arranged to extend into and mechanically anchor within the tibia and the second end extending out of said tibia through said cut-out into a closely fitted engagement with said disc-shaped sliding member thereby actively connecting the femur with the tibia.
Claim 3
Dependent Claim
75 words
An implantable knee joint, as set forth in claim 1, wherein said disc-shaped sliding member comprises a cylindrical surface and a pair of spaced end surfaces extending transversely of the cylindrical surface and arranged to abut the bony tissures of said resected condyles, said cylindrical surface being located adjacent the inner surface of said cap with said cylindrical surface extending laterally outwardly from said oblong cut-out on both sides thereof extending in the oblong direction.
Claim 4
Dependent Claim
32 words
An implantable knee joint, as set forth in claim 1 or 2, wherein the inner surface of said cap extending along and adjoining said cut-out in the oblong direction thereof. is polished.
Claim 5
Dependent Claim
22 words
An implantable knee joint, as set forth in claim 1 or 2, wherein the outer surface of said femoral cap is polished.
Claim 6
Dependent Claim
58 words
An implantable knee joint, as set forth in claim 1 or 2, wherein said bearing surfaces each have a first end part and a second end part extending in and spaced apart in the circumferential direction by a third part and said first end part extends circumferentially for an angular extend in the range of 130° to 190°.
Claim 7
Dependent Claim
58 words
An implantable knee joint, as set forth in claim 1 or 2, wherein said bearing surfaces each have a first end part and a second end part extending in and spaced apart in the circumferential direction by a third part and said second end part extends angularly in the circumferential direction in the range of 120° to 160°.
Claim 8
Dependent Claim
67 words
An implantable knee joint, as set forth in claim 1 or 2, wherein said bearing surfaces each have a first end part and a second end part extending in and spaced apart in the circumferential direction by a third part and said third part in the direction extending between said first and second end parts has an inside radius in the range of 20 to 150 mm.
Claim 9
Dependent Claim
29 words
An implantable knee joint, as set forth in claim 1 or 2, wherein the wall thickness of said femoral cap is in the range of 4 to 20 mm.
Claim 10
Dependent Claim
28 words
An implantable knee joint, as set forth in claim 5, wherein the inside radius of said first end part is in the range of 8 to 25 mm.
Claim 11
Dependent Claim
27 words
An implantable knee joint, as set forth in claim 6, wherein the inside radius of said second end part is in the range 4 to 15 mm.
Claim 12
Dependent Claim
32 words
An implantable knee joint, as set forth in claim 5, wherein said oblong cut-out extends angularly in the circumferential direction of said first end part in the range of 90° to 140°.
Claim 13
Dependent Claim
34 words
An implantable knee joint, as set forth in claim 1 or 2, wherein a guide sleeve is located around said connecting member in the region where said connecting member extends through said oblong cut-out.
Claim 14
Dependent Claim
21 words
An implantable knee joint, as set forth in claim 2, wherein said cylindrical surface of said disc-shaped sliding member is polished.
Claim 15
Dependent Claim
21 words
An implantable knee joint, as set forth in claim 13, wherein said end faces of said disc-shaped sliding member are polished.
Claim 16
Dependent Claim
48 words
An implantable knee joint, as set forth in claim 12, wherein said disc-shaped sliding has a frusto-conical bore located therein extending inwardly from said cylindrical surface and said connecting member has a complementary frusto-conical surface thereon arranged to engage in said frusto-conical bore in said disc-shaped sliding member.
Claim 17
Dependent Claim
28 words
An implantable knee joint, as set forth in claim 1 or 2, wherein said tibial member comprises a tibial cap arranged to cooperate operatively with said femoral cap.
Claim 18
Dependent Claim
18 words
An implantable knee joint, as set forth in claim 16, wherein said tibial cap is C-shaped in cross-section.
Claim 19
Dependent Claim
44 words
An implantable knee joint, as set forth in claim 16, wherein said tibial cap has a region thereon corresponding to the eminentia intercondylaris, and said tibial cap has a bore extending through the region corresponding to the eminential intercondylaris for receiving said connecting member.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-05-04 | 1990-11-03 | 1991-05-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-05-04 | 1994-11-03 | 1995-05-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-05-04 | 1998-11-03 | 1999-05-05 | $7700.00 | Window Closed / Lapsed |