Implant comprising calcium cement and hydrophobic liquid

Details Implant comprising calcium cement and hydrophobic liquid Implant comprising calcium cement and hydrophobic liquid

2001-07-19

2003-11-04

Yoon, Tae H. (Department: 1714)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Processes of preparing a desired or intentional composition...

C523S113000, C523S116000, C524S127000, C524S801000, C524S803000, C424S425000, C424S501000, C424S502000

Reexamination Certificate

active

06642285

ABSTRACT:

This invention concerns a composition in accordance with the pre-characterising portion of claim 1 and a method for producing hardened calcium-containing cement particles or a porous calcium-containing matrix for use in the human or animal body according to the pre-characterising portion of claim 47.
The porous calcium-containing matrix block or round calcium-containing particles are obtained by combining a calcium-containing hydraulic cement paste with a hydrophobic solution such that (i) the calcium-containing hydraulic cement paste is obtained by mixing one or several powders with an aqueous lubricant; (ii) the lubricant comprises water; (iii) the calcium-containing cement paste hardens with time; (iv) the hydrophobic solution hardly dissolves or do not dissolve in the calcium-containing paste and vice versa; (v) the calcium-containing cement paste and the hydrophobic solution are mixed together to form a so-called emulsion. Depending on the composition of the emulsion, the emulsion is made out of particles of the calcium-containing paste in the hydrophobic solution or out of particles of the hydrophobic solution in the calcium-containing paste; (vi) The mixing of the emulsion is stopped at a given time to obtain either calcium-containing particles floating in the hydrophobic solution or a calcium-containing matrix having pores filled with the hydrophobic solution.
Calcium phosphates are known to be biocompatible and in most cases osteoconductive. They represent therefore a good alternative to bone grafting. Different forms have been given to calcium phosphates. In most cases, calcium phosphate are sold as granules of about 0.5 to 2.0 mm diameter. Just before implantation, the granules are mixed with the blood of the patient and applied to the desired place. The advantage of this technique is its simplicity and the fact that bone can easily grow in between the granules. However, the granules do not hold together and can migrate away from the defect. For example in the dental area, ceramic granules can migrate out from the gingiva into the mouth which is for obvious reasons not desirable. Furthermore, most commercial granules cannot be easily packed in large amounts in a given defect, because they are not round. Calcium phosphates are also sold as block. On the contrary to granules, blocks can have rather large mechanical properties, but they cannot be shaped according to the bone defect. Furthermore, it is difficult to fabricate a block that has an open-porous structure enabling a rapid bone ingrowth, and when it is the case, the block has low mechanical properties. Another alternative to sell calcium phosphates is as cements. The cements are made of a mixture of one or several calcium phosphate powders and one aqueous solution. Upon mixture with the aqueous solution, the calcium phosphate powders dissolve and precipitate into another calcium phosphate. Through this precipitation, the paste hardens forming a fine and homogeneous nanoporous or microporous matrix. Such so-called calcium phosphate cements are moldable and injectable, and can have rather large mechanical properties (e.g. more than 100 MPa in compressive strength). However, these cements do not have an open macropprosity enabling a rapid bone ingrowth. In this patent, we are presenting a method and compositions that respond to the problems described above, i.e. enable the obtention of, among others
a highly-resistant open-macroporous matrix;
an injectable open-macroporous matrix; or
round calcium phosphate particles.
The present invention as claimed aims at solving the above described problems. The present invention provides a cement as defined in claim 1 and a method for producing hardened calcium-containing cement particles or a porous calcium-containing matrix for use in the human or animal body as defined in claim 47.
The various features of novelty that characterize the invention are pointed out with particularity in the claims annexed to and forming part of this disclosure. For the better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be made to the accompanying examples in which preferred embodiments of the invention are illustrated in detail.
Further in this description, the use of calcium phosphate hydraulic cement paste will be described. However, calcium sulphate hydraulic cement (gypsum) can also be used and should be therefore included in the calcium phosphate hydraulic cement.
The principle of this invention is to mix a calcium phosphate hydraulic cement paste with a hydrophobic liquid. If the composition of the cement and the hydrophobic liquid are well-chosen, an emulsion is obtained. It can be an emulsion of the cement paste in the hydrophobic liquid or of the hydrophobic liquid in the calcium phosphate paste. If the cement paste hardens in a optimized way, the emulsion can be frozen in its actual structure leading to either a hydrophobic liquid entrapped in a calcium phosphate matrix or calcium phosphate particles or structure floating in a hydrophobic liquid. In the case of a hydrophobic liquid entrapped in a calcium phosphate matrix, the shape, the volume and the interconnectivity of the pores filled with the hydrophobic liquid can be varied depending on the composition of the initial mixture. The possibilities are described herein.
Preferably the hydrophobic liquid is selected from the group of:
ricinoleic acid (C
17
H
33
OCOOH), linoleic acid (C
17
H
31
COOH), palmitic acid (C
15
H
31
COOH), palmitoleic acid (C
15
H
29
COOH), stearic acid (C
17
H
35
COOH), linolenic acid (C
17
H
29
COOH), arachidic acid (C
19
H
39
COOH), myristic acid (C
13
H
27
COOH), lauric acid (C
11
H
23
COOH), capric acid (C
9
H
19
COOH), caproic acid (C
5
H
11
COOH), oleic acid (C
17
H
33
COOH), caprylic acid (C
7
H
15
COOH), erucic acid (C
21
H
41
COOH), butyric acid (C
3
H
7
COOH), ethyl myristate (C
13
H
27
COOC
2
H
5
), ethyl oleate (C
17
H
33
COOC
2
H
5
), ethyl palmitate (C
15
H
31
COOC
2
H
5
), ethyl linoleate (C
17
H
31
COOC
2
H
5
), ethyl laurate (C
11
H
23
COOC
2
H
5
), ethyl linolenate (C
17
H
29
COOC
2
H
5
), ethyl stearate (C
17
H
35
COOC
2
H
5
), ethyl arachidate (C
19
H
39
COOC
2
H
5
), ethyl caprilate (C
7
H
15
COOC
2
H
5
), ethyl caprate (C
9
H
19
COOC
2
H
5
), ethyl caproate (C
5
H
11
COOC
2
H
5
), ethyl butyrate (C
3
H
7
COOC
2
H
5
), triacetin (C
9
H
14
O
6
), alpha tocopherol (C
29
H
50
O
2
), beta tocopherol (C
28
H
48
O
2
), delta tocopherol (C
27
H
46
O
2
), gamma tocopherol (C
28
H
48
O
2
), benzyl alcohol (C
7
H
8
O), benzyl benzoate (C
14
H
12
O
2
), methylphenol (C
7
H
8
O), di-n-butyl sebacate (C
18
H
34
O
4
), diethylphthalate (C
12
H
14
O
4
), glyceryl monooleate (C
21
H
40
O
4
), lecithin [CAS registry number 8002-43-5], medium chain triglycerides, mineral oil [CAS registry number 8012-95-1], petrolatum [CAS registry number 8009-03-8], and liquid paraffines.
The vegetal oil—as a hydrophobic liquid—is a preferably selected from the group of:
canula oil [no CAS registry number], corn oil [CAS registry number 8001-30-7], cottonseed oil [CAS registry number 8001-29-4], peanut oil [CAS registry number 8002-03-7], sesame oil [CAS registry number 8008-74-0], castor oil [CAS registry number 8001-79-4], and soybean oil [CAS registry number 8001-22-7].
The first component comprises preferably:
calcium sulphate hemihydrate [CaSO
4
·½H
2
O], calcium pyrophosphate [Ca
2
P
2
O
7
], calcium carbonate [CaCO
3
], monocalcium phosphate monohydrate [Ca(H
2
PO
4
)
2
·H
2
O], monocalcium phosphate [Ca(H
2
PO
4
)
2
], anhydrous dicalcium phosphate [CaHPO
4
], dicalcium phosphate dihydrate [CaHPO
4
.2H
2
O], octocalcium phosphate [Ca
8
H
2
(PO
4
)
6
·5H
2
O], alpha-tricalcium phosphate [alpha-Ca
3
(PO
4
)
2
], beta-tricalcium phosphate [beta-Ca
3
(PO
4
)
2
], hydroxyapatite [Ca
5
(PO
4
)
3
OH], tetracalcium phosphate [Ca
4

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