CA2003247C - Bone screw - Google Patents
Bone screwInfo
- Publication number
- CA2003247C CA2003247C CA002003247A CA2003247A CA2003247C CA 2003247 C CA2003247 C CA 2003247C CA 002003247 A CA002003247 A CA 002003247A CA 2003247 A CA2003247 A CA 2003247A CA 2003247 C CA2003247 C CA 2003247C
- Authority
- CA
- Canada
- Prior art keywords
- segment
- bone screw
- threaded
- transition
- diameter
- 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.)
- Expired - Lifetime
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
- 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, setting implements or the like
- 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
Abstract
A bone screw has a smooth shaft segment, a threaded segment and a tapered transition segment between the shaft and the threaded segment.
Description
Bone Screw 2003247 Field of The Invention This invention relates to bone screws and particularly to bone screws of the so-called Schanz type. Such screws have a screw head, a smooth shank segment, and a threaded segment.
Backqround Of The Invention With conventional designs of Schanz screws, with any additional load on the screw in a radial direction, the driving pressure is reinforced on one side while being relieved on the other because of the absence of pre-stress. This can lead to a loosening of the screw and subsequent bone resorption. (cf. S.M.
Perren, R. Ganz, and A. Ruter, Med. OrthoP. Technik, Heft 1/75, 95 Jahrg. (1975) pp.6-10). In addition, with conventional Schanz screws, two drilling p-rocedures are necessary, one with a drill for the minor diameter d1 and the other with a drill for the major diameter d2. If one tries to simplify the procedure by forming a single, undersized hole, micro and macro fractures occur in the bone material.
In conventional Schanz screws the transition between the shank and thread segments; both of which have the same outside diameter, is formed as a channel that either punches the bone material along its leading edge or cuts it along its back edge.
There is not merely a radial spreading of the bone material.
,, 1-20032~7 Summary Of The Invention In accordance with the invention, a bone screw is provided which can be inserted with only one drilling procedure, under radial compression of the bone material, without bone injury, and which retains the radial driving pressure along with the entire surface even under additional functional loads.
Such results are obtained in accordance with the invention by means of a bone screw having a head, a smooth shaft segment having a diameter Dl, adjacent said head, a threaded segment, and a transition segment between the shaft segment and the threaded segment, said transition segment tapering from a diameter Dl adjacent the shaft segment to a diameter D2 adjacent the threaded segment, the ratio Dl -- D2 .
being less than the breaking elongation of the bone and between about 0.001 and 0.040.
Brief Description Of The Drawinqs The-invention will be further described with reference to the accompanying drawings in which:
Fig. 1 is a view in elevation, partly broken away, of a bone screw in accordance with the invention.
Fig. 2 is a view in elevation of a fragment of a modified version of the bone screw of Fig. 1.
Fig. 3 is a view in elevation of a fragment of a differently modified version of the bone screw of Fig. 1.
, ~
~ 20032~7 Detailed Description of The Invention Referring to Fig. 1, a bone screw according to the invention comprises a screw head 1, a smooth shaft segment 2, having a diameter D1 and a threaded segment 3 having a minor diameter dl and a major diameter d2. Between the shaft segment 2 and the threaded segment 3 is located a tapered transition segment 4. In the embodiment shown in Fig. 1 the transition segment is conically shaped and narrows continuously from diameter Dl to a lesser diameter D2. The free end 6 of the threaded segment 3 is constructed as an automatically expanding screw tip (Trocar tip).
The breaking elongation of a bone will normally be about 2-3%. The size of the transition segment should be selected so that the ratio Dl -- D2 is less than the breaking elongation of the bone, i.e. from about 0.001 to about 0.040 preferably between about 0.010 and 0.030.
This range will result in optimum compression of bone material.
The diameter D2 at the narrower end of the transition segment should advantageously correspond to the major diameter d2 A
` 20032~7 of the threaded segment to guarantee sufficient compression of the bone material by the smooth shaft segment.
The threaded segment is preferably dimensioned so that the ratio between the minor and ma~or diameter, dl/d2 is between about 0.80 and about 0.89, preferably between about 0.83 and about 0.86.
To prevent simultaneous action by the threaded segment on the rear corticalis and by the transition segment on the front corticalis, which would lead to loss of control when the bone screw is screwed in, it is advantageous to position the transition segment at a distance of from about 11 to about 15mm, preferably from about 12 to about 14mm from the free end of the threaded segment, i.e., the end remote from the transition segment.
In a specific example of a screw according to Fig. 1 the shaft segment may have a diameter Dl of 4.5mm, and the threaded segment may have major and minor diameters of 4.4mm and 3.8mm, respectively. The end of the transition segment has a diameter, D2, equal to 4.4mm, the major diameter d2 of the thread.
The distance between the transition segment 4 and the tip of segment 3 is about 13mm.
In Fig. 2 there is shown a modification of a screw according to the invention in which a milling segment 5 having straight longitudinal lands and groves is interposed between the ~ 20032~7 transition segment 4, which is constructed as a shoulder, and the threaded segment 3.
A further embodiment of the invention is shown in fig.
3. There the transition segment 4 is formed with a shallow thread. This will ensure further advance of the screw into the bone, even before the rear cortical wall is reached.
Backqround Of The Invention With conventional designs of Schanz screws, with any additional load on the screw in a radial direction, the driving pressure is reinforced on one side while being relieved on the other because of the absence of pre-stress. This can lead to a loosening of the screw and subsequent bone resorption. (cf. S.M.
Perren, R. Ganz, and A. Ruter, Med. OrthoP. Technik, Heft 1/75, 95 Jahrg. (1975) pp.6-10). In addition, with conventional Schanz screws, two drilling p-rocedures are necessary, one with a drill for the minor diameter d1 and the other with a drill for the major diameter d2. If one tries to simplify the procedure by forming a single, undersized hole, micro and macro fractures occur in the bone material.
In conventional Schanz screws the transition between the shank and thread segments; both of which have the same outside diameter, is formed as a channel that either punches the bone material along its leading edge or cuts it along its back edge.
There is not merely a radial spreading of the bone material.
,, 1-20032~7 Summary Of The Invention In accordance with the invention, a bone screw is provided which can be inserted with only one drilling procedure, under radial compression of the bone material, without bone injury, and which retains the radial driving pressure along with the entire surface even under additional functional loads.
Such results are obtained in accordance with the invention by means of a bone screw having a head, a smooth shaft segment having a diameter Dl, adjacent said head, a threaded segment, and a transition segment between the shaft segment and the threaded segment, said transition segment tapering from a diameter Dl adjacent the shaft segment to a diameter D2 adjacent the threaded segment, the ratio Dl -- D2 .
being less than the breaking elongation of the bone and between about 0.001 and 0.040.
Brief Description Of The Drawinqs The-invention will be further described with reference to the accompanying drawings in which:
Fig. 1 is a view in elevation, partly broken away, of a bone screw in accordance with the invention.
Fig. 2 is a view in elevation of a fragment of a modified version of the bone screw of Fig. 1.
Fig. 3 is a view in elevation of a fragment of a differently modified version of the bone screw of Fig. 1.
, ~
~ 20032~7 Detailed Description of The Invention Referring to Fig. 1, a bone screw according to the invention comprises a screw head 1, a smooth shaft segment 2, having a diameter D1 and a threaded segment 3 having a minor diameter dl and a major diameter d2. Between the shaft segment 2 and the threaded segment 3 is located a tapered transition segment 4. In the embodiment shown in Fig. 1 the transition segment is conically shaped and narrows continuously from diameter Dl to a lesser diameter D2. The free end 6 of the threaded segment 3 is constructed as an automatically expanding screw tip (Trocar tip).
The breaking elongation of a bone will normally be about 2-3%. The size of the transition segment should be selected so that the ratio Dl -- D2 is less than the breaking elongation of the bone, i.e. from about 0.001 to about 0.040 preferably between about 0.010 and 0.030.
This range will result in optimum compression of bone material.
The diameter D2 at the narrower end of the transition segment should advantageously correspond to the major diameter d2 A
` 20032~7 of the threaded segment to guarantee sufficient compression of the bone material by the smooth shaft segment.
The threaded segment is preferably dimensioned so that the ratio between the minor and ma~or diameter, dl/d2 is between about 0.80 and about 0.89, preferably between about 0.83 and about 0.86.
To prevent simultaneous action by the threaded segment on the rear corticalis and by the transition segment on the front corticalis, which would lead to loss of control when the bone screw is screwed in, it is advantageous to position the transition segment at a distance of from about 11 to about 15mm, preferably from about 12 to about 14mm from the free end of the threaded segment, i.e., the end remote from the transition segment.
In a specific example of a screw according to Fig. 1 the shaft segment may have a diameter Dl of 4.5mm, and the threaded segment may have major and minor diameters of 4.4mm and 3.8mm, respectively. The end of the transition segment has a diameter, D2, equal to 4.4mm, the major diameter d2 of the thread.
The distance between the transition segment 4 and the tip of segment 3 is about 13mm.
In Fig. 2 there is shown a modification of a screw according to the invention in which a milling segment 5 having straight longitudinal lands and groves is interposed between the ~ 20032~7 transition segment 4, which is constructed as a shoulder, and the threaded segment 3.
A further embodiment of the invention is shown in fig.
3. There the transition segment 4 is formed with a shallow thread. This will ensure further advance of the screw into the bone, even before the rear cortical wall is reached.
Claims (13)
1. A bone screw having a head, a smooth shaft segment having a diameter D1 adjacent said head, a threaded segment and a transition segment between the smooth shaft segment and the threaded segment, said transition segment tapering from a diameter D1 adjacent said smooth shaft segment to a lesser diameter D2 adjacent said threaded segment, the ratio being between about 0.001 and 0.040.
2. The bone screw claimed in claim 1, wherein the ratio is between 0.010 and 0.030.
3. The bone screw claimed in claim 1, wherein the transition segment has a self-cutting thread.
4. The bone screw claimed in claim 1, wherein the transition segment narrows continuously from D1 to D2.
5. The bone screw claimed in claim 1, wherein the transition segment has a shallow thread.
6. The bone screw claimed in claim 1 and comprising a milling segment between the threaded segment and the transition segment.
7. The bone screw claimed in claim 1, wherein the threaded segment has a minor diameter d1 and a major diameter d2, the ratio d1/d2 being between about 0.80 and 0.89.
8. The bone screw claimed in claim 7, wherein the ratio is between about 0.83 and 0.86.
9. The bone screw claimed in claim 1, wherein the threaded segment has an automatically expanding screw tip at its end remote from the transition segment.
10. The bone screw claimed in claim 9, wherein the tip is a Trocar tip.
11. The bone screw claimed in claim 1, wherein the transition segment is from about 11 to about 15mm from the remote end of the threaded segment.
12. The bone screw claimed in claim 11, wherein the transition segment is from about 12 to about 14mm from the remote end of the threaded segment.
13. The bone screw claimed in claim 1, wherein the tip of the threaded segment has a corkscrew shape.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH04263/88-3 | 1988-11-17 | ||
| CH4263/88A CH681957A5 (en) | 1988-11-17 | 1988-11-17 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2003247A1 CA2003247A1 (en) | 1990-05-17 |
| CA2003247C true CA2003247C (en) | 1996-02-20 |
Family
ID=4272883
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002003247A Expired - Lifetime CA2003247C (en) | 1988-11-17 | 1989-11-17 | Bone screw |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US5019078A (en) |
| EP (1) | EP0369266B1 (en) |
| JP (1) | JPH0691888B2 (en) |
| AT (1) | ATE129880T1 (en) |
| CA (1) | CA2003247C (en) |
| CH (1) | CH681957A5 (en) |
| DE (1) | DE58909487D1 (en) |
Families Citing this family (45)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE9017101U1 (en) * | 1990-12-19 | 1991-04-11 | Gerhard Hug Gmbh, 7801 Umkirch, De | |
| US5584887A (en) * | 1991-08-15 | 1996-12-17 | Smith & Nephew Richards, Inc. | Percutaneous screw adapter |
| FR2680461B1 (en) * | 1991-08-19 | 1993-11-26 | Fabrication Mat Orthopedique | IMPLANT FOR OSTEOSYNTHESIS DEVICE, ESPECIALLY OF THE RACHIS, AND CORRESPONDING DEVICE FOR ITS PLACEMENT. |
| US5275601A (en) * | 1991-09-03 | 1994-01-04 | Synthes (U.S.A) | Self-locking resorbable screws and plates for internal fixation of bone fractures and tendon-to-bone attachment |
| US5217461A (en) * | 1992-02-20 | 1993-06-08 | Acromed Corporation | Apparatus for maintaining vertebrae in a desired spatial relationship |
| US5397356A (en) * | 1993-01-15 | 1995-03-14 | Depuy Inc. | Pin for securing a replacement ligament to a bone |
| US6030162A (en) * | 1998-12-18 | 2000-02-29 | Acumed, Inc. | Axial tension screw |
| US5964768A (en) * | 1993-01-21 | 1999-10-12 | Acumed, Inc. | Tapered bone screw with continuously varying pitch |
| US6984235B2 (en) * | 1993-01-21 | 2006-01-10 | Acumed Llc | System for fusing joints |
| US5871486A (en) * | 1993-01-21 | 1999-02-16 | Acumed, Inc. | Variable pitch bone screw |
| US9161793B2 (en) | 1993-01-21 | 2015-10-20 | Acumed Llc | Axial tension screw |
| EP0746253B1 (en) * | 1993-01-21 | 2002-05-02 | Acumed Inc. | Tapered bone screw with continuously varying pitch |
| US8070786B2 (en) | 1993-01-21 | 2011-12-06 | Acumed Llc | System for fusing joints |
| US6299615B1 (en) | 1993-01-21 | 2001-10-09 | Acumed, Inc. | System for fusing joints |
| EP0642323B1 (en) * | 1993-03-25 | 1999-03-03 | Pennig, Dietmar, Dr. | Fixing pin for osteosynthesis |
| US5609595A (en) * | 1993-03-25 | 1997-03-11 | Pennig; Dietmar | Fixation pin for small-bone fragments |
| DE4339804A1 (en) * | 1993-11-23 | 1995-06-01 | Haerle Anton | Power transmission link for osteosynthesis work |
| US6264676B1 (en) | 1996-11-08 | 2001-07-24 | Scimed Life Systems, Inc. | Protective sheath for transvaginal anchor implantation devices |
| US8080058B2 (en) * | 2003-04-01 | 2011-12-20 | Depuy Mitek, Inc. | Method and apparatus for fixing a graft in a bone tunnel |
| AU9661298A (en) * | 1997-09-05 | 1999-03-22 | Richard J. Deslauriers | Self-retaining anchor track and method of making and using same |
| US6096041A (en) * | 1998-01-27 | 2000-08-01 | Scimed Life Systems, Inc. | Bone anchors for bone anchor implantation device |
| US6660010B2 (en) | 1998-01-27 | 2003-12-09 | Scimed Life Systems, Inc. | Bone anchor placement device with recessed anchor mount |
| DE69916045T2 (en) | 1998-05-12 | 2004-08-05 | Boston Scientific Ltd., St. Michael | HAND-OPERATED BONE ANCHOR SETTING DEVICE |
| US6585769B1 (en) | 1999-04-05 | 2003-07-01 | Howmedica Osteonics Corp. | Artificial spinal ligament |
| US6409768B1 (en) * | 2000-03-16 | 2002-06-25 | Slobodan Tepic | Screw anchored joint prosthesis |
| US6468277B1 (en) | 2000-04-04 | 2002-10-22 | Ethicon, Inc. | Orthopedic screw and method |
| US6878166B2 (en) * | 2000-08-28 | 2005-04-12 | Ron Clark | Method and implant for securing ligament replacement into the knee |
| US7235079B2 (en) | 2004-11-18 | 2007-06-26 | Acumed Llc | Composite bone fasteners |
| US6746451B2 (en) * | 2001-06-01 | 2004-06-08 | Lance M. Middleton | Tissue cavitation device and method |
| US20050101961A1 (en) * | 2003-11-12 | 2005-05-12 | Huebner Randall J. | Bone screws |
| US7896917B2 (en) * | 2003-10-15 | 2011-03-01 | Biomet Sports Medicine, Llc | Method and apparatus for graft fixation |
| US20050165487A1 (en) * | 2004-01-28 | 2005-07-28 | Muhanna Nabil L. | Artificial intervertebral disc |
| US8142462B2 (en) | 2004-05-28 | 2012-03-27 | Cavitech, Llc | Instruments and methods for reducing and stabilizing bone fractures |
| US8002778B1 (en) | 2004-06-28 | 2011-08-23 | Biomet Sports Medicine, Llc | Crosspin and method for inserting the same during soft ligament repair |
| US8740955B2 (en) * | 2005-02-15 | 2014-06-03 | Zimmer, Inc. | Bone screw with multiple thread profiles for far cortical locking and flexible engagement to a bone |
| DE202006019220U1 (en) | 2006-12-19 | 2007-05-24 | Zrinski Ag | Orthopedic screw fastening system for fixing at bone of patient, has through-holes cut on one another so that intersection line and surfaces are produced in direction of plate thickness, where line and surfaces co-operate with head windings |
| US8147546B2 (en) * | 2007-03-13 | 2012-04-03 | Biomet Sports Medicine, Llc | Method and apparatus for graft fixation |
| US20080294167A1 (en) * | 2007-05-21 | 2008-11-27 | Brian Schumacher | Articulating cavitation device |
| US20090082817A1 (en) | 2007-07-20 | 2009-03-26 | Cochlear Limited | Coupling apparatus for a bone anchored hearing device |
| DE502009000626D1 (en) * | 2009-02-16 | 2011-06-16 | Stryker Trauma Ag | Bone screw and manufacturing method for this |
| WO2010094032A2 (en) | 2009-02-16 | 2010-08-19 | Aoi Medical Inc. | Trauma nail accumulator |
| US8366719B2 (en) | 2009-03-18 | 2013-02-05 | Integrated Spinal Concepts, Inc. | Image-guided minimal-step placement of screw into bone |
| US20110106157A1 (en) * | 2009-10-30 | 2011-05-05 | Warsaw Orthropedic, Inc. | Self-Locking Interference Bone Screw for use with Spinal Implant |
| US8523914B2 (en) * | 2010-01-28 | 2013-09-03 | Warsaw Orthopedic, Inc. | Bone anchor with predetermined break point and removal features |
| WO2013013218A2 (en) * | 2011-07-20 | 2013-01-24 | Horwitz Michael H | Minimal incision removable bone screw, driver, and method of use |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2082457A5 (en) * | 1970-03-17 | 1971-12-10 | Scialom Jacques | |
| DE7625614U1 (en) * | 1976-08-14 | 1977-01-13 | Howmedica International, Inc. Zweigniederlassung Kiel, 2300 Kiel | Tab screw for connecting bone parts, especially in the case of femoral neck fractures |
| US4463753A (en) * | 1980-01-04 | 1984-08-07 | Gustilo Ramon B | Compression bone screw |
| FR2517536B1 (en) * | 1981-12-09 | 1986-12-12 | Zbikowski Juan | FUNCTIONAL FIXING DEVICE FOR OSTEO-SYNTHESIS USING COMPRESSION PLATES |
| DE3241963C1 (en) * | 1982-11-12 | 1984-04-26 | Feldmühle AG, 4000 Düsseldorf | Helical jaw implant |
| IL80705A0 (en) * | 1985-11-28 | 1987-02-27 | Jaquet Orthopedie | Transcutaneous pin for fixation of a bone part or fragment |
| US4913134A (en) * | 1987-07-24 | 1990-04-03 | Biotechnology, Inc. | Spinal fixation system |
-
1988
- 1988-11-17 CH CH4263/88A patent/CH681957A5/de not_active IP Right Cessation
-
1989
- 1989-11-04 EP EP89120436A patent/EP0369266B1/en not_active Expired - Lifetime
- 1989-11-04 AT AT89120436T patent/ATE129880T1/en not_active IP Right Cessation
- 1989-11-04 DE DE58909487T patent/DE58909487D1/en not_active Expired - Lifetime
- 1989-11-17 JP JP1297760A patent/JPH0691888B2/en not_active Expired - Fee Related
- 1989-11-17 US US07/437,581 patent/US5019078A/en not_active Expired - Lifetime
- 1989-11-17 CA CA002003247A patent/CA2003247C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| US5019078A (en) | 1991-05-28 |
| JPH02198543A (en) | 1990-08-07 |
| EP0369266B1 (en) | 1995-11-08 |
| DE58909487D1 (en) | 1995-12-14 |
| JPH0691888B2 (en) | 1994-11-16 |
| EP0369266A3 (en) | 1990-10-24 |
| CH681957A5 (en) | 1993-06-30 |
| CA2003247A1 (en) | 1990-05-17 |
| ATE129880T1 (en) | 1995-11-15 |
| EP0369266A2 (en) | 1990-05-23 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKEX | Expiry |