US4000525A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ceramic prosthetic implant suitable for a knee joint plateau
Assignee: United States Department of the Navy
•
Filing: 1975-08-21
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Granted: 1977-01-04
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Expires: 1995-08-21
Abstract
Abstract A ceramic prosthesis of high aluminum oxide suitable for the tibial plateau of a knee joint with the superior (upper) portion of the prosthesis being of a high density AL 2 O 3 having a very low porosity and the inferior (lower) portion being of high density AL 2 O 3 having a high degree of porosity capable of accepting bone growth.
Inventors
- 👤 Jerome J. Klawitter
- 👤 Nazir A. Bhatti
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 17:27
CPC Classifications
A; A61; A61F; A61F2/00; A61F2/02; A61F2/30; A61F2/38; A61F2/389; A61F2/30767; B; B32; B32B; B32B18/00; C; C04; C04B; C04B35/00; C04B35/01; C04B35/10; C04B35/111; C04B38/00; C04B38/06; C04B38/0615; A61F2002/30001; A61F2002/30003; A61F2002/30004; A61F2002/30011; A61F2/3094; A61F2002/30971; A61F2002/3895; A61F2250/00; A61F2250/0014; A61F2250/0023; A61F2250/0024; A61F2310/00; A61F2310/00005; A61F2310/00179; A61F2310/00185; A61F2310/00203; A61F2310/00389; A61F2310/00592; A61F2310/00598; A61F2310/00604; C04B2235/00; C04B2235/65; C04B2235/656; C04B2235/6567; C04B2237/00; C04B2237/30; C04B2237/32; C04B2237/34; C04B2237/343; C04B2237/50; C04B2237/58; C04B2237/586
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
47 words
A prosthesis comprising a porous layer having approximately 96 weight percent of aluminum oxide and a porosity in the range of 40-60% with interconnecting pores, laminated to a dense layer of approximately 96 weight percent of aluminum oxide having a porosity of not greater than 1 percent.
Claim 2
Dependent Claim
47 words
A prosthesis comprising a porous layer having approximately 96 weight percent of aluminum oxide and a porosity in the range of 40-60% with interconnecting pores, laminated to a dense layer of approximately 96 weight percent of aluminum oxide having a porosity of not greater than 1 percent.
Claim 3
Dependent Claim
34 words
A prosthesis as defined in claim 1 wherein said porous layer has an exposed planar surface and pore diameters in the approximate range of 300-500 micrometers, said dense layer having a smooth outer surface.
Claim 4
Dependent Claim
27 words
A prosthesis according to claim 2 wherein said porous layer has a minimum thickness of 1 centimeter and said dense layer has a thickness of 1 centimeter.
Claim 5
Dependent Claim
37 words
A prosthesis according to claim 1 wherein the oxide composition of the aluminum oxide material is as follows ______________________________________
Oxide Weight Percent
______________________________________
Alpha AL.sub.2 O.sub.3
96
SiO.sub.2 2.7
MgO 1.0
CaO 0.2
Na.sub.2 O 0.1
______________________________________
Claim 6
Dependent Claim
97 words
A prosthesis designed as an implant for the tibial plateau of a knee joint comprising: a. a first dense layer of high aluminum oxide ceramic material having a smooth outer surface to articulate with the femoral condyle; b. a second porous layer of high aluminum oxide ceramic material laminated to said first layer and having a planar surface adapted to engage said tibial plateau, c. said dense layer having a porosity not greater than 1 percent; and d. said porous layer having a porosity in the range of 40-60 percent with interconnecting pores of controlled pore size.
Claim 7
Dependent Claim
97 words
A prosthesis designed as an implant for the tibial plateau of a knee joint comprising: a. a first dense layer of high aluminum oxide ceramic material having a smooth outer surface to articulate with the femoral condyle; b. a second porous layer of high aluminum oxide ceramic material laminated to said first layer and having a planar surface adapted to engage said tibial plateau, c. said dense layer having a porosity not greater than 1 percent; and d. said porous layer having a porosity in the range of 40-60 percent with interconnecting pores of controlled pore size.
Claim 8
Dependent Claim
34 words
A prosthesis according to claim 5 wherein the aluminum oxide content of each of said layers is approximately 96 percent, the pore diameters of said porous layer being in the range of 350-500 micrometers.
Claim 9
Dependent Claim
86 words
A completely ceramic prosthesis for use as a bone implant in a joint comprising: a. a layer of high aluminum oxide material having a porosity in the range of 40-60% with interconnecting pores; b. said layer having a planar surface; and c. a dense layer of high aluminum oxide material having a porosity not greater than 1% laminated to said first porous layer at said planar surface; d. the outer surface of said dense layer being smooth to act as an articulate surface in said joint.
Claim 10
Dependent Claim
86 words
A completely ceramic prosthesis for use as a bone implant in a joint comprising: a. a layer of high aluminum oxide material having a porosity in the range of 40-60% with interconnecting pores; b. said layer having a planar surface; and c. a dense layer of high aluminum oxide material having a porosity not greater than 1% laminated to said first porous layer at said planar surface; d. the outer surface of said dense layer being smooth to act as an articulate surface in said joint.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-01-04 | 1980-07-05 | 1981-01-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-01-04 | 1984-07-05 | 1985-01-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-01-04 | 1988-07-05 | 1989-01-04 | $7700.00 | Window Closed / Lapsed |