GB2370619A - Bone screw - Google Patents
Bone screw Download PDFInfo
- Publication number
- GB2370619A GB2370619A GB0031776A GB0031776A GB2370619A GB 2370619 A GB2370619 A GB 2370619A GB 0031776 A GB0031776 A GB 0031776A GB 0031776 A GB0031776 A GB 0031776A GB 2370619 A GB2370619 A GB 2370619A
- Authority
- GB
- United Kingdom
- Prior art keywords
- screw
- bone
- interval
- threads
- fixation
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 210000000988 bone and bone Anatomy 0.000 title claims abstract description 30
- 208000010392 Bone Fractures Diseases 0.000 claims description 18
- 238000013461 design Methods 0.000 claims description 5
- 238000003780 insertion Methods 0.000 claims description 4
- 230000037431 insertion Effects 0.000 claims description 4
- 206010017076 Fracture Diseases 0.000 description 18
- 230000001054 cortical effect Effects 0.000 description 10
- 238000010079 rubber tapping Methods 0.000 description 6
- 230000000399 orthopedic effect Effects 0.000 description 5
- 230000006835 compression Effects 0.000 description 4
- 238000007906 compression Methods 0.000 description 4
- 239000012634 fragment Substances 0.000 description 4
- 230000006641 stabilisation Effects 0.000 description 4
- 238000006386 neutralization reaction Methods 0.000 description 2
- AFJYYKSVHJGXSN-KAJWKRCWSA-N selamectin Chemical compound O1[C@@H](C)[C@H](O)[C@@H](OC)C[C@@H]1O[C@@H]1C(/C)=C/C[C@@H](O[C@]2(O[C@@H]([C@@H](C)CC2)C2CCCCC2)C2)C[C@@H]2OC(=O)[C@@H]([C@]23O)C=C(C)C(=N\O)/[C@H]3OC\C2=C/C=C/[C@@H]1C AFJYYKSVHJGXSN-KAJWKRCWSA-N 0.000 description 2
- 230000000087 stabilizing effect Effects 0.000 description 2
- VRDIULHPQTYCLN-UHFFFAOYSA-N Prothionamide Chemical compound CCCC1=CC(C(N)=S)=CC=N1 VRDIULHPQTYCLN-UHFFFAOYSA-N 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 239000007943 implant Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910001092 metal group alloy Inorganic materials 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B17/00—Surgical instruments, devices or methods
- A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
- A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws or setting implements
- A61B17/68—Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
- A61B17/84—Fasteners therefor or fasteners being internal fixation devices
- A61B17/86—Pins or screws or threaded wires; nuts therefor
- A61B17/8625—Shanks, i.e. parts contacting bone tissue
- A61B17/863—Shanks, i.e. parts contacting bone tissue with thread interrupted or changing its form along shank, other than constant taper
Landscapes
- Health & Medical Sciences (AREA)
- Orthopedic Medicine & Surgery (AREA)
- Surgery (AREA)
- Life Sciences & Earth Sciences (AREA)
- Heart & Thoracic Surgery (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- Engineering & Computer Science (AREA)
- Biomedical Technology (AREA)
- Neurology (AREA)
- Medical Informatics (AREA)
- Molecular Biology (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Surgical Instruments (AREA)
Abstract
A bone screw has a head (2) and a shank with threaded portions (4, 8) at either end. A portion (6) of the shank between the two threaded portions (4, 8) is unthreaded and has a diameter which is less than the external diameters of the threaded portions (4, 8).
Description
INTERVAL THREADED BONE FIXATION SCREW
CRGSSMPLMNUFTUBELATED APPLICATIONS N/A
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
N/A BACKGKOUNMF INVENTION
While the methods, compositions and materials presented herein may be used in a variety of applications, they were specifically developed'with respect to interval threaded bone fixation screw. Therefore as background, relevant details relating to bone fixation screws and problems overcome by this invention are provided.
Two broad bone fixation screw devices are currently in use for the treatment of fractures namely, cancettous screws, and cortical screws. These two classes of screws are-further designed with threads spanning the whole length of the shank portion of a screw (fully threaded screws), or with threads spanning a distat section of the screw usually fifty percent of tw length or less (partially threaded). Cortical screws generally have shallow threads, large core diameters allowing for increased resistance during insertion. Partially threadedTbrms of cortical screws are called shaft screws but with the shaft diameter and external diameter of the thread having equal diameter which makes it suitable fbrinterfragmentary compression of fracture fragments. Cancellous screws however, have thin core diameter, wide and deep threads allowing for better holding power of the softer and spongy trabeculae of cancellous bone. When partially threaded cancellous screws are used, they serve as tag screws with the threaded portion of the screw in the distal part of the two fractured bone fragments. The proximal portion of a lag screw is preferred to devoid of thread, to allow easy glide through the pre-drilted hole in a bone. This is particularly relevant when the screw is used in conjunction with a stabilizing fracture plate, allowing full concentration of the compressive force on the distal fracture fragment. After drilling a cortical bone for screw insertion, tapping of the drilled hole is generally done to create an established thread path that matches that of the screw to be inserted : The rap makes the step of screw insertion easier.
Tapping is commonly avoided as a step in the fixation of cancelous bone fractures. This is because of the cockscrew shape of the screw with increasing thread diameter.
In the last few years, self tapping cortical screws have been introduced by adding a cutting flute on the leading thread allowing it to cut is path as if is progressively advanced with a screw driver.
Stable positioning of a screw is affected by its ability to resist pull-out. This in turn is proportional to the surface area of thread that is in contact with bone. The higher the number of threads per length of a screw (smaller the pitch), the greater the fixation. In simple fracture patterns requiring stabilisation without inierfragmentary compression, or fractures requiring stabilisation with a neutralization plate, a fully threaded screw while ensuring stronghold on the bone can be replaced with an interval* fixation screw of this invention. It achieves comparable fixation of fracture and because of the presence of the segment of screw devoid of threads but consisting of a smooth surface with a wider external diameter is able to withstand significant stress across the fracture site. The smooth surface of the segment of the screw between the proximal and distal threaded portions also allows easy removat of the screw whenever screw removal is desired.
This invention is directed at providing an interval threaded screw that can be used in the treatment of bone fractures either atone, or in combination with a fracture plate.
BRIEF SUMMARY OF INVENTION
This present invention relates to an intervatfixation screw for fixation of fractures alone or in combination with a fixation plate. It relates to an interval fixation screw having similarities to existing screws used in fracture fixation, bur with a limited numbered threads positioned at its proximal and distal segments leaving a significant segment of the screw with a shank portion
devoid of threads". The describedintervarixation screw is particularly useful in stabilizing fracture plates to the length of a fractured bone, and alone in the fixation of fracture fragments that do not require interfragmentary compression. If also allows a single screw design., to be used for both cortical and cancellous bones since the threads are only limited to the cortices on the either side of the diameter of a bone wittrthe the spongy medufary bone thartypicalty differentiates a cancellous bone from a cortical bone devoid of threads. When desired thread and screw design can be made to match characteristics of existing cancellous or corticar screws bur with the essential feature of an interval fixation screw maintained. In simple fracture patterns requiring stabilisation without interfragmentary compression, or fracture ? requiring stabilisation with a neutralization plate, a fully threaded screw while ensuring strong hold on the bone can be replaced with an interval fixation screw of this invention. It achieves comparable fixation offrapture and because of the presence of the segment of screw devoid of threads but consisting of a smooth surface with a wider external diameter is able to withstand significant stress across the fracture site. The smooth surface of the segment of the screw between the proximal and distal threaded portions also allows easy removal of the screw whenever screw removal is desired.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. I is a perspective view of an imerval bfuation screw device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION
White this invention is-susceptible of embodiment in many different teems, the drawings and specification describe in detail preferred embodiments of the invention. It should be understood,
however, that the disdosure is-to be consicterectas-an exempliftcatior of the principles of the invention. The disclosure is not intended to limit the broadest aspects of the invention to the illustrated embodiments
Fig. t is a perspective view of an interval bone fixation screw device for use in fixation of fractures of a bone alone, or in combination with a fracture fixation plate.
Like most orthopedic screws, the interval fixation screw preferably has a screw head 2, which connects immediately to a short threaded segment that replaces the shaft portion of existing
cancerous screws. This threaded'proximat'segmenr4'has a variable number of threads ranging from two to ten depending on the diameter of the bone requiring fixation. The core diameter of this threaded* proximar segment will matctr existing dimensions in uscn orthopedic fixation implants, usually 3.0 mm for 4.5 mm cortical, the 6.5 mm cancellous, and the 4.5 mm malleolar screws.
The threaded proximal segment 4, then connects to an unthreaded'portMn 6 having an external diameter comparable to that of shaft diameter as established in current orthopedic screw fixation devices The wider diameter of this portion of the interval screw device increases the screw strength in bending which is a function of the increased radius and cross-swectional moment of inertia. This unthreaded portion of the screw wits'have a diameter tzar matches that established for existing orthopedic fixation screw devices. This unthreaded shaft portion is of a variable length
depending on the overatj length of the screw and'the nature of bone for which it is meant for, and may occupy between twenty percent to ninety percent of the overall length of the screw. The unthreaded portion 6 of the interval fixation screw then connects-with a istally threaded portion 8 of the screw having same diameter characteristics as the proximally threaded portion as well as thread design characteristics. The distally threaded portion of the interval fixation screw tapers to form a tip 10 that is characteristic of most orthopedic fixation screws. The shaft diameter (of the unthreaded protion) may be the same or slightly besser diameterthan thafofthe outer diameter of the cutting edges of the threads on the threaded portion of the screws. The pitch (distance
between two adjacenr threads), and the thread'angle wi !'be as currentlyestablished in the design of cortical and cancellous screws in the treatment of bone fractures. Preferably the threads of the interval'fixation screw are self-tapping, bur rapping may be requned in cortical bones.
To apply the interval fixation screw to a bone, a hole is pre-drilled with matching drill and the appropriate screw size is inserted-using a screw driver unfit-the fult'length is inserted into bone.
Preferably the edges of the thread should be self tapping, but when the shaft diameter is about the same size as the thready outerdiameterin the distaliy andproximany threaded segments, a separate tapping device is desirable. The interval fixation screw is preferably made of stainless steel'alloy or other metal alloy combination.
Claims (6)
1. An intend screw fixation device for use in the treatment of bone fractures having a tubular shape with cutting threads limited to the proximal and distal portions of the screw, and having an intermediate portion devoid-of threads taving a diameter slightly smaller, or the same as the external diameter of the threaded portions.
2. The interval fixation screw of claim wherein the threadectporttons, have threads varying from two to ten depending on its diameter, and having the same thread design characteristics with regard'to pitch dimensions, screw angte and'threadextemal diameter.
3 The interval fixation screw of claim 1, wherein there is preferably a head portion that immediately connects to the proximal threaded portion designated to engage the near cortex of a bone.
4 The interval'ixation screw of claim 1, wherein the proximally threaded portion connects to smooth surface shaft that preferably comprises between fifty and ninety percent of the overall length of the screw, and designated to occupy the medullary portion of a bone between the near and farther cortices.
5. The interval fixation screw of claim 1, wherein the distally threaded portion is connected to the smooth intermediate shaft portion having two or more threads designated for the engagement of the farther cortex of a bone
6. The interval fixation screw of claim 1, wherein the distally threaded portion terminates in a tip enabling the insertion of the screw into a prie-dried hole in a bone.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0031776A GB2370619A (en) | 2000-12-29 | 2000-12-29 | Bone screw |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0031776A GB2370619A (en) | 2000-12-29 | 2000-12-29 | Bone screw |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB0031776D0 GB0031776D0 (en) | 2001-02-07 |
| GB2370619A true GB2370619A (en) | 2002-07-03 |
Family
ID=9905984
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0031776A Withdrawn GB2370619A (en) | 2000-12-29 | 2000-12-29 | Bone screw |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2370619A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1723920A3 (en) * | 2005-05-20 | 2007-01-03 | DePuy Products, Inc. | Bone fixation system |
| ES2267358A1 (en) * | 2004-09-08 | 2007-03-01 | Mariano Nuñez-Samper Pizarroso | Compression screw for osteo-synthesis of mini bone fragments, has four-lobed track, defined at screw head, which forms threaded orifice for fixation to threaded inner rod of screwdriver |
| US7828828B2 (en) | 2005-04-14 | 2010-11-09 | Warsaw Orthopedic, Inc | Intervertebral joint |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1565178A (en) * | 1977-02-24 | 1980-04-16 | Interfix Ltd | Bone screw |
| GB2108229A (en) * | 1981-10-16 | 1983-05-11 | Howse And Company Limited D | Bone fixation screws |
| US5019079A (en) * | 1989-11-20 | 1991-05-28 | Zimmer, Inc. | Bone screw |
| WO1991009572A1 (en) * | 1989-12-21 | 1991-07-11 | Bakinsky Nauchno-Issledovatelsky Institut Travmatologii I Ortopedii | Compressing screw for osteosynthesis |
| US5536127A (en) * | 1994-10-13 | 1996-07-16 | Pennig; Dietmar | Headed screw construction for use in fixing the position of an intramedullary nail |
| WO1998040024A1 (en) * | 1997-03-11 | 1998-09-17 | Biotech International (S.A.R.L.) | Screw with threaded head for bone fragment osteosynthesis |
-
2000
- 2000-12-29 GB GB0031776A patent/GB2370619A/en not_active Withdrawn
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1565178A (en) * | 1977-02-24 | 1980-04-16 | Interfix Ltd | Bone screw |
| GB2108229A (en) * | 1981-10-16 | 1983-05-11 | Howse And Company Limited D | Bone fixation screws |
| US5019079A (en) * | 1989-11-20 | 1991-05-28 | Zimmer, Inc. | Bone screw |
| WO1991009572A1 (en) * | 1989-12-21 | 1991-07-11 | Bakinsky Nauchno-Issledovatelsky Institut Travmatologii I Ortopedii | Compressing screw for osteosynthesis |
| US5536127A (en) * | 1994-10-13 | 1996-07-16 | Pennig; Dietmar | Headed screw construction for use in fixing the position of an intramedullary nail |
| WO1998040024A1 (en) * | 1997-03-11 | 1998-09-17 | Biotech International (S.A.R.L.) | Screw with threaded head for bone fragment osteosynthesis |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ES2267358A1 (en) * | 2004-09-08 | 2007-03-01 | Mariano Nuñez-Samper Pizarroso | Compression screw for osteo-synthesis of mini bone fragments, has four-lobed track, defined at screw head, which forms threaded orifice for fixation to threaded inner rod of screwdriver |
| ES2267358B1 (en) * | 2004-09-08 | 2008-02-16 | Mariano Nuñez-Samper Pizarroso | COMPRESSION SCREW FOR OSTEOSYNTHESIS OF MINIFRAGMENTS. |
| US7828828B2 (en) | 2005-04-14 | 2010-11-09 | Warsaw Orthopedic, Inc | Intervertebral joint |
| EP1723920A3 (en) * | 2005-05-20 | 2007-01-03 | DePuy Products, Inc. | Bone fixation system |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0031776D0 (en) | 2001-02-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |