Patent EP0107476A2 successfully refreshed from Google Patents.
EP0107476A2
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Bone graft substitute
Assignee: Calcitek Inc
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Filing: 1983-10-18
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Granted: —
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Expires: 2003-10-18
Abstract
Abstract A bone graft has a dense calcium-phosphate ceramic core and porous calcium-phosphate ceramic surface layers for directly obtaining viable bone-growth surfaces. The graft is implanted as a replacement or extension segment for a natural bone segment or to repair a deformity with its porous end layers in intimate contact with osseous material at prepared ends of the bone. The dense core provides the required flexural and compressive strength whereas the porous surface layers promote bone ingrowth that fuses the bone to the graft.
Inventors
- 👤 John F. Kay
- 👤 Donald M. Comstock
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 13:19
CPC Classifications
A; A61; A61F; A61F2/00; A61F2/02; A61F2/30; A61F2/46; A61F2/4644; A61B; A61B17/00; A61B17/56; A61B17/58; A61F2/28; A61F2/2803; A61L; A61L27/00; A61L27/28; A61L27/30; A61L27/32; A61F2/3094; A61F2002/2835; A61F2/30942; A61F2002/30957; A61F2002/30968; A61F2310/00; A61F2310/00005; A61F2310/00179; A61F2310/00293; A61F2310/00389; A61F2310/00592; A61F2310/00796; A61L2430/00; A61L2430/02
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
86 words
A bone graft comprising a solid non-porous ceramic core of substantially pure calcium-phosphate ceramic material, the core having a flexural strength of at least about 137MN/m 2 and a compressive strength of at least 550MN/m 2 , and a bone-contact end surface in the form of substantially pure calcium-phosphate ceramic material, said bone-contact surface being integral with said core and having a porosity of between about 10 and about 60 percent by volume, said bone-contact surface having a thickness between about 0.25 and about 4 mm.
Claim 2
Dependent Claim
86 words
A bone graft comprising a solid non-porous ceramic core of substantially pure calcium-phosphate ceramic material, the core having a flexural strength of at least about 137MN/m 2 and a compressive strength of at least 550MN/m 2 , and a bone-contact end surface in the form of substantially pure calcium-phosphate ceramic material, said bone-contact surface being integral with said core and having a porosity of between about 10 and about 60 percent by volume, said bone-contact surface having a thickness between about 0.25 and about 4 mm.
Claim 3
Dependent Claim
20 words
A bone graft according to Claim 1 wherein said ceramic material is of at least about 97 percent pure calcium-phosphate.
Claim 4
Dependent Claim
23 words
A graft according to Claim 1 wherein said calcium-phosphate ceramic material is selected from the group consisting of hydroxylapatite, whitlockite and mixtures thereof.
Claim 5
Dependent Claim
17 words
A graft according to Claim 1 wherein said core is hydroxylapatite and said bone-contact surface is whitlockite,
Claim 6
Dependent Claim
24 words
. 5. A graft according to Claim 1 for implantation as a bone spacer comorising a core having two spaced-apart porous bone-contact end surfaces.
Claim 7
Dependent Claim
37 words
A graft according to Claim 5 wherein the maximum cross-sectional dimension of said graft is about 40 mm and the thickness of said core between said spaced-apart end surfaces is between about 2.5 and about 40 mm.
Claim 8
Independent Claim
159 words
A method of forming a ceramic bone graft or the like comprising providing a mold cavity having generally the desired shape of a bone graft, depositing in said mold cavity a core layer and a surface layer, said core layer comprising substantially pure calcium-phosphate ceramic material, said surface layer comprising between about 40 to about 90 volume percent substantially pure calcium-phosphate particulate ceramic material, and between about 10 to about 60 volume percent of particulate organic material which volatilizes away within a temperature range of about 100°C and 1050°C, said surface layer being deposited at a thickness of between about 0.5 mm and about 8.0 mm, compacting said deposited layers in said mold at pressures between about 55 and about 175MPa, and heating said compacted layers to a temperature of between about 1050°C and about 1300°C for a period sufficient to sinter said particulate layers into a graft with a dense, non-porous core and an integral porous surface layer.
Claim 9
Independent Claim
159 words
A method of forming a ceramic bone graft or the like comprising providing a mold cavity having generally the desired shape of a bone graft, depositing in said mold cavity a core layer and a surface layer, said core layer comprising substantially pure calcium-phosphate ceramic material, said surface layer comprising between about 40 to about 90 volume percent substantially pure calcium-phosphate particulate ceramic material, and between about 10 to about 60 volume percent of particulate organic material which volatilizes away within a temperature range of about 100°C and 1050°C, said surface layer being deposited at a thickness of between about 0.5 mm and about 8.0 mm, compacting said deposited layers in said mold at pressures between about 55 and about 175MPa, and heating said compacted layers to a temperature of between about 1050°C and about 1300°C for a period sufficient to sinter said particulate layers into a graft with a dense, non-porous core and an integral porous surface layer.
Claim 10
Dependent Claim
19 words
A method according to Claim 7 wherein said ceramic material is at least about 97 percent calcium-phosphate ceramic material.
Claim 11
Dependent Claim
23 words
A method according to Claim 7 wherein said calcium-phosphate ceramic material is selected from the group consisting of hydroxylapatite, whitlockite and mixtures thereof.
Claim 12
Dependent Claim
23 words
A method according to Claim 7 wherein said dense core layer is substantially pure hydroxylapatite and said surface layer is substantially pure whitlockite.
Claim 13
Dependent Claim
30 words
A method according to Claim 7 wherein said dense core layer is substantially pure hydroxylapatite and said surface layer is a mixture of substantially pure whitlockite and substantially pure hydroxylapatite.
Claim 14
Dependent Claim
24 words
A method according to Claim 7 wherein said compacted layers are sintered for a period of from about 10 minutes to about 200 minutes.
Claim 15
Dependent Claim
24 words
A method according to Claim 7 including depositing within said mold a second surface layer of particulate organic material mixed with calcium-phosphate ceramic material.
Claim 16
Dependent Claim
24 words
A method according to Claim 7 wherein said ceramic material sifts through a screen having openings in the range of about 50-200 microns square.
Claim 17
Dependent Claim
36 words
A method according to Claim 14 wherein said powdered organic material particles sift through a screen having square openings with dimensions between two and seven times those of the screen through which said ceramic particles sift.
Claim 18
Dependent Claim
11 words
A method according to Claim 7 including machining said sintered graft.
Claim 19
Dependent Claim
20 words
A method according to Claim 7 wherein said compacted layers are sintered at a temperature of between 1050°C and 1300°C.
Claim 20
Dependent Claim
17 words
A method according to Claim 7 wherein said compacted layers are sintered at between 1100°C and 1175°C.
Claim 21
Dependent Claim
21 words
A method according to Claim 7 wherein said organic material volatilizes at a temperature of between about 100°C and about 275°C.
Claim 22
Dependent Claim
23 words
A method according to Claim 7 wherein said organic material is selected from the group consisting of PVA, PEG, urea and combinations thereof.
References Cited (Backward Citations)
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