US5716359A
Expired / Lapsed
US
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Anchor and method for fixing a screw in bone
Assignee: Pentax Corp
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Filing: 1996-05-29
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Granted: 1998-02-10
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Expires: 2016-05-29
Abstract
Abstract An anchor including a shank formed from a hardened product of a calcium phosphate compound. The anchor having a strength capable of retaining its original shape, before, during and after insertion into a pre-drilled hole of a bone, and a brittleness capable of causing its original shape to disintegrate as a result of a breakage of the shank upon an application of a driving force from the screw to the shank during a driving of the screw through the anchor inserted in the bone. The present invention also relates to a method for fixing a screw in a bone. Using the anchor of the present invention, it becomes possible to easily and reliably fix a screw in a bone having a reduced strength.
Inventors
- 👤 Satoshi Ojima
- 👤 Masahiro Kohketsu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:06
CPC Classifications
A; A61; A61B; A61B17/00; A61B17/56; A61B17/58; A61B17/68; A61B17/686; A61L; A61L31/00; A61L31/02; A61L31/026; A61B17/70; A61B2017/00004; Y; Y10; Y10S; Y10S606/00; Y10S606/907
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
136 words
An anchor to be inserted into a pre-drilled hole of a bone, thereby assisting a fixation of a screw in the bone, comprising in combination: a shank composed of hardened product of calcium phosphate compound; said shank comprising a screw-receiving hole and having a strength capable of retaining an original shape, before, during and after insertion into said pre-drilled hole; and said shank further having a brittleness capable of causing said original shape to disintegrate as a result of a breakage of said shank upon application of a driving force from said screw to said shank when said screw is driven through said anchor inserted in the bone; and a screw, said screw comprising a portion sized to be insertable into said hole and a portion having a diameter greater than the diameter of said hole.
Claim 2
Dependent Claim
136 words
An anchor to be inserted into a pre-drilled hole of a bone, thereby assisting a fixation of a screw in the bone, comprising in combination: a shank composed of hardened product of calcium phosphate compound; said shank comprising a screw-receiving hole and having a strength capable of retaining an original shape, before, during and after insertion into said pre-drilled hole; and said shank further having a brittleness capable of causing said original shape to disintegrate as a result of a breakage of said shank upon application of a driving force from said screw to said shank when said screw is driven through said anchor inserted in the bone; and a screw, said screw comprising a portion sized to be insertable into said hole and a portion having a diameter greater than the diameter of said hole.
Claim 3
Dependent Claim
24 words
The anchor according to claim 1, wherein said calcium phosphate compound has a molar ratio of calcium to phosphorous of about 1.5 to 2.0.
Claim 4
Dependent Claim
29 words
The anchor according to claim 2, wherein said calcium phosphate compound comprises at least one member selected from a group consisting of hydroxyapatite, fluoroapatite, tricalcium phosphate and tetracalcium phosphate.
Claim 5
Dependent Claim
13 words
The anchor according to claim 3, wherein said calcium phosphate compound comprises hydroxyapatite.
Claim 6
Dependent Claim
27 words
The anchor according to claim 1, wherein said hardened product is a sintered product of said calcium phosphate compound having a porosity of about 40 to 80%.
Claim 7
Dependent Claim
27 words
The anchor according to claim 1, wherein said hardened product is a molded product of said calcium phosphate compound having a porosity of about 20 to 70%.
Claim 8
Dependent Claim
27 words
The method according to claim 5, wherein said shank has a diameter and a length substantially the same as that of said pre-drilled hole in the bone.
Claim 9
Dependent Claim
31 words
The anchor according to claim 5, wherein said shank is a column-shaped body having a diameter of about 1.5 to 5.0 mm and a length of about 15 to 60 mm.
Claim 10
Dependent Claim
16 words
The anchor according to claim 8, wherein said screw-receiving hole is bored in said column-shaped body.
Claim 11
Dependent Claim
29 words
The anchor according to claim 1, said anchor being used to drive and fix a screw in a weakened portion of a bone of a patient suffering from osteoporosis.
Claim 12
Independent Claim
123 words
A method of fixing a screw in a bone, comprising: drilling a hole in a predetermined site in the bone; inserting an anchor into said pre-drilled hole, wherein said anchor comprises a shank composed of hardened product of calcium phosphate compound, said shank having a strength capable of retaining an original shape, before, during and after insertion into said pre-drilled hole, said shank also having a brittleness capable of causing said original shape to disintegrate as a result of a breakage of said shank upon application of a driving force from said screw to said shank when said screw is driven through said anchor inserted in the bone; and driving said screw through said anchor inserted in said bone to disintegrate said anchor.
Claim 13
Independent Claim
123 words
A method of fixing a screw in a bone, comprising: drilling a hole in a predetermined site in the bone; inserting an anchor into said pre-drilled hole, wherein said anchor comprises a shank composed of hardened product of calcium phosphate compound, said shank having a strength capable of retaining an original shape, before, during and after insertion into said pre-drilled hole, said shank also having a brittleness capable of causing said original shape to disintegrate as a result of a breakage of said shank upon application of a driving force from said screw to said shank when said screw is driven through said anchor inserted in the bone; and driving said screw through said anchor inserted in said bone to disintegrate said anchor.
Claim 14
Dependent Claim
27 words
The method according to claim 11, wherein said hardened product is a sintered product of said calcium phosphate compound having a porosity of about 40 to 80%.
Claim 15
Dependent Claim
27 words
The method according to claim 11, wherein said hardened product is a molded product of said calcium phosphate compound having a porosity of about 20 to 70%.
Claim 16
Dependent Claim
31 words
The method according to claim 12, wherein said shank is a column-shaped body having a diameter of about 1.5 to 5.0 mm and a length of about 15 to 60 mm.
Claim 17
Dependent Claim
16 words
The method according to claim 14, wherein said column-shaped body has a screw-receiving hole bored therein.
Claim 18
Dependent Claim
24 words
The method according to claim 11, wherein said screw is driven into a weakened portion of a bone of a patient suffering from osteoporosis.
Claim 19
Dependent Claim
15 words
The method according to claim 14, wherein said column-shaped body has a screw-receiving hole therein.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 2001-02-09 | 2001-08-11 | 2002-02-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-02-09 | 2005-08-11 | 2006-02-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-02-09 | 2009-08-11 | 2010-02-10 | $7700.00 | Window Closed / Lapsed |