WO1990002526A1 - Screw - Google Patents

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Publication number
WO1990002526A1
WO1990002526A1 PCT/AU1989/000386 AU8900386W WO9002526A1 WO 1990002526 A1 WO1990002526 A1 WO 1990002526A1 AU 8900386 W AU8900386 W AU 8900386W WO 9002526 A1 WO9002526 A1 WO 9002526A1
Authority
WO
WIPO (PCT)
Prior art keywords
screw
region
thread
depth
bone
Prior art date
Application number
PCT/AU1989/000386
Other languages
French (fr)
Inventor
David Keith Livingston Blair
John Raymond Selmes
Original Assignee
Australian Defence Industries Pty. Limited
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority to AUPJ0351 priority Critical
Priority to AUPJ035188 priority
Application filed by Australian Defence Industries Pty. Limited filed Critical Australian Defence Industries Pty. Limited
Publication of WO1990002526A1 publication Critical patent/WO1990002526A1/en

Links

Classifications

    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00Surgical instruments, devices or methods, e.g. tourniquets
    • A61B17/56Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
    • A61B17/58Surgical 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
    • A61B17/68Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
    • A61B17/84Fasteners therefor or fasteners being internal fixation devices
    • A61B17/86Threaded wires, pins or screws; Nuts therefor
    • A61B17/8625Shanks, i.e. parts contacting bone tissue
    • A61B17/863Shanks, i.e. parts contacting bone tissue with thread interrupted or changing its form along shank, other than constant taper
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61FFILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/02Prostheses implantable into the body
    • A61F2/30Joints
    • A61F2/30767Special external or bone-contacting surfaces, e.g. coating for improving bone ingrowth
    • A61F2/30771Special external or bone-contacting surfaces, e.g. coating for improving bone ingrowth applied in original prostheses, e.g. holes or grooves
    • A61F2002/3085Special external or bone-contacting surfaces, e.g. coating for improving bone ingrowth applied in original prostheses, e.g. holes or grooves with a threaded, e.g. self-tapping, bone-engaging surface, e.g. external surface
    • A61F2002/30861Special external or bone-contacting surfaces, e.g. coating for improving bone ingrowth applied in original prostheses, e.g. holes or grooves with a threaded, e.g. self-tapping, bone-engaging surface, e.g. external surface having threads of increasing or decreasing height

Abstract

The present invention discloses a screw (10) adapted for insertion into a bone and in particular a vertebra. The screw (10) is divided into two distinct regions (16 and 18) with the depth of the screw thread (20, 22) in each region being different to that in each other region whilst the overall diameter of the screw (10) is substantially constant over the length of the screw (10).

Description

SCREW

Field of the Invention

The present invention relates to a screw having a multi-thread profile adapted for insertion into bone, and in particular, into a vertebra. Following fracture of a bone it is necessary to immobilise the fractured bone, or limb, to allow the bone fragments to heal. In some cases, in particular in fractures of the spine, this is achieved using a fixation system comprising screws and a supporting plate or rod. In the case of a spinal fracture this fixation system is used to immobolise one or more spinal segments till a bone graft placed around the segment to be immobilised gains sufficient strength to immobilise the segment.

The fixation system requires anchorage points above and below the segment to be fused to which are attached longitudinal bars or plates providing the longitudinal stability. In the case of a spinal fracture the screws are typically referred to as pedicle screws as they are passed through the pedicle of the vertebra. Each pedicle screw is set in a hole drilled down through the pedicle into the centrum or body of the vertebra. The pedicle is the solid narrow bone adjoining the centrum which supports the neural arch. The centrum is composed of a type of bone called concellouε. Cancellous bone is crumbly, peppered with small voids, and not very strong.

In the case of a spinal fracture, the pedicle screw is expected to maintain a high degree of anchorage in the supporting vertebra irrespective of the applied stress conditions. It must be resilient and strong enough to withstand the effects of both static and dynamic loading on the spine and not fracture or fail. The body of the screw, especially the upper portion needs, therefore, to be as broad as possible to maximise strength. However, as the major thread diameter of the screw must be significantly less than the diameter of the pedicle at its narrowest point, a shallow thread profile is obligatory. As a consequence of the somewhat mutually exclusive requirements of maximum screw strength and preservation of pedicle integrity, prior art pedicle screws typically have a uniformly wide body with a low thread profile to minimise the major diameter of the screw. As a result of using uniformly low thread profile, existing pedicle screws are liable to fail through extraction, as they may be pulled out of the crumbly cancellous bone when subjected to stress applied under extreme loading. They are, therefore, suspect means of support and/or stability for use in a spinal fracture fixation system.

As strength and stability are major operational factors, the present inventors have designed a novel screw of relatively uniform major thread diameter with distinct segments of different thread profiles.

Accordingly, the present invention consists in a screw adapted for insertion into a bone, the screw being characterised in that the screw is divided into at least two distinct regions, the depth of the screw thread in each region being different to that in each other region, whilst the overall diameter of the screw is substantially constant over the length of the screw.

In a preferred embodiment of the present invention the screw is divided into two distinct regions.

In a further preferred embodiment of the present invention the depth of the screw thread in the region proximate the head of the screw is less than the depth of the screw thread in the region remote from the screw head. In yet a further preferred embodiment of the present invention the screw is adapted for insertion into a vertebra through its pedicle.

It is presently preferred that the upper face of the screw is substantially perpendicular to the base of the screw. As will be recognised by persons skilled in the art such an arrangement results in the screw having greater resistance to extraction.

In order that the nature of the present invention may be more clearly understood a preferred form thereof will now be described with reference to the accompanying drawings, in whic :-

Figure 1 shows a longitudinal cross-section of the screw of the present invention;

Figure 2 shows an expanded cross-sectional view of the screw thread of the upper region of the screw shown in Fig. 1; and

Figure 3 shows an expanded cross-sectional view of the screw thread of the lower region of the screw shown in Fig. 1. As shown in Figure 1 the screw 10 comprises a head 12 (detail not shown) and a body portion 14. The body portion is divided into two distinct regions 16 and 18, with region 16 being proximate screw head 12. As can clearly be seen in this drawing the depth of the screw thread 20 in region 16 is less than the depth of the screw thread 22 in region 18, whilst the diameter of the base 24 in region 16 is greater than the diameter of the base 26 in region 18. This results in the overall diameter of the screw is substantially constant over the entire length of the screw.

As is best shown in Figs. 2 and 3 the upper face of screw threads 20 and 22 are perpendicular to bases 24 and 26 respectively.

As will be readily apparent to persons skilled in the art, when the screw of the present invention is adapted for insertion into a vertebra the segment of the screw contacting the pedicle retains maximum strength by employing a low thread profile on a high diameter base, whilst the segment of the screw contacting the centrum maximises stability by the use of a thread profile which is as deep as possible to obtain optimum anchorage in this type of bone on a low (narrow) diameter base.

This screw therefore provides firmer anchorage in the vertebal body without sacrificing strength through the use of a wide base - low thread profile in its upper region which will be in the pedicle, and a narrow base - high thread profile in the lower half of the shaft which will be in the cancellous bone of the centrum.

From the foregoing description, it should be apparent that the invention encompasses an advantageous advance in the art. Further, it should be clear that the invention may be embodiment in other specific forms without departing from the spirit of the essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims

CLAIMS :
1. A screw adapted for insertion into a bone, the screw being characterised in that the screw is divided into at least two distinct regions, the depth of the screw thread in each region being different to that in each other region, whilst the overall diameter of the screw is substantially constant over the length of the screw.
2. A screw as claimed in claim 1 in which the screw is divided into two distinct regions.
3. A screw as claimed in claim 1 or claim 2 in which the depth of the screw thread in the region proximate the screw head is less than the depth of the screw thread in the region remote from the screw head.
4. A screw as claimed in any one of claims 1 to 3 in which the screw is adapted for insertion into a vertebra through its pedicle.
5. A screw substantially as hereinbefore described with reference to the accompanying drawing.
PCT/AU1989/000386 1988-09-09 1989-09-11 Screw WO1990002526A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AUPJ0351 1988-09-09
AUPJ035188 1988-09-09

Publications (1)

Publication Number Publication Date
WO1990002526A1 true WO1990002526A1 (en) 1990-03-22

Family

ID=3773358

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AU1989/000386 WO1990002526A1 (en) 1988-09-09 1989-09-11 Screw

Country Status (1)

Country Link
WO (1) WO1990002526A1 (en)

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0472017A1 (en) * 1990-08-24 1992-02-26 Anton Prof. Dr. Härle Cylindrical bodies with external thread
EP0491211A1 (en) * 1990-12-19 1992-06-24 Synthes AG, Chur Bone screw
US5147363A (en) * 1989-12-21 1992-09-15 Haerle Anton Screw for use in osteosynthesis
FR2739151A1 (en) * 1995-09-22 1997-03-28 Numedic Fixing screw for bone implants
US5964768A (en) * 1993-01-21 1999-10-12 Acumed, Inc. Tapered bone screw with continuously varying pitch
US6030162A (en) * 1998-12-18 2000-02-29 Acumed, Inc. Axial tension screw
WO2000032125A1 (en) * 1998-11-26 2000-06-08 Synthes Ag Chur Screw
US6299615B1 (en) 1993-01-21 2001-10-09 Acumed, Inc. System for fusing joints
US6468277B1 (en) 2000-04-04 2002-10-22 Ethicon, Inc. Orthopedic screw and method
EP1393689A2 (en) * 1997-02-11 2004-03-03 MICHELSON, Gary Karlin Anterior cervical plating system and bone screw
WO2004086991A1 (en) 2003-04-03 2004-10-14 Stratec Medical Ag Bone screw
GB2406056A (en) * 2003-09-17 2005-03-23 Corin Ltd Bone tapping kit, fixation member and prosthetic cup
US6875215B2 (en) * 2002-02-15 2005-04-05 John Stanley Taras Distraction pin for fracture fixation
WO2005058175A1 (en) 2003-12-19 2005-06-30 Depuy International Limited A bone screw
US6916320B2 (en) 1997-02-11 2005-07-12 Gary K. Michelson Anterior cervical plate system
US6984235B2 (en) 1993-01-21 2006-01-10 Acumed Llc System for fusing joints
US7077844B2 (en) 1997-02-11 2006-07-18 Sdgi Holdings, Inc. Segmentable skeletal plating system
US8974506B2 (en) 2009-11-09 2015-03-10 Spinewelding Ag Medical device, apparatus, and surgical method
US9161793B2 (en) 1993-01-21 2015-10-20 Acumed Llc Axial tension screw
US10335216B2 (en) 2011-07-15 2019-07-02 Globus Medical, Inc. Screw implants for bone fusion

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1562811A (en) * 1967-09-27 1969-04-11
AU5965869A (en) * 1968-09-09 1971-02-25 Illinois Toolworks, Inc Screw-type fasteners
CH546351A (en) * 1971-11-22 1974-02-28 Litton Export Trade Corp Self-locking screw.
AU1344176A (en) * 1975-04-28 1977-11-03 Downs Surgical Limited Surgical screw implant
AU3329878A (en) * 1977-02-24 1979-08-23 Interfix Ltd. Bone screw
EP0129404A1 (en) * 1983-06-15 1984-12-27 ITW Limited Fixings including screws and clamp plates
EP0144503B1 (en) * 1983-09-02 1986-11-26 Friedr. Boesner GmbH Connecting element for two machine parts or structural parts,for example extensible fit screw
AU1280088A (en) * 1987-03-13 1988-09-15 Societe De Fabrication De Materiel Orthopedique - Sofamor Vertebral screw for an osteosynthesis device in particular of the lumbar and dorsal rachis

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1562811A (en) * 1967-09-27 1969-04-11
AU5965869A (en) * 1968-09-09 1971-02-25 Illinois Toolworks, Inc Screw-type fasteners
CH546351A (en) * 1971-11-22 1974-02-28 Litton Export Trade Corp Self-locking screw.
AU1344176A (en) * 1975-04-28 1977-11-03 Downs Surgical Limited Surgical screw implant
AU3329878A (en) * 1977-02-24 1979-08-23 Interfix Ltd. Bone screw
EP0129404A1 (en) * 1983-06-15 1984-12-27 ITW Limited Fixings including screws and clamp plates
EP0144503B1 (en) * 1983-09-02 1986-11-26 Friedr. Boesner GmbH Connecting element for two machine parts or structural parts,for example extensible fit screw
AU1280088A (en) * 1987-03-13 1988-09-15 Societe De Fabrication De Materiel Orthopedique - Sofamor Vertebral screw for an osteosynthesis device in particular of the lumbar and dorsal rachis

Cited By (41)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5147363A (en) * 1989-12-21 1992-09-15 Haerle Anton Screw for use in osteosynthesis
EP0472017A1 (en) * 1990-08-24 1992-02-26 Anton Prof. Dr. Härle Cylindrical bodies with external thread
EP0491211A1 (en) * 1990-12-19 1992-06-24 Synthes AG, Chur Bone screw
US6984235B2 (en) 1993-01-21 2006-01-10 Acumed Llc System for fusing joints
US5964768A (en) * 1993-01-21 1999-10-12 Acumed, Inc. Tapered bone screw with continuously varying pitch
US9161793B2 (en) 1993-01-21 2015-10-20 Acumed Llc Axial tension screw
US6299615B1 (en) 1993-01-21 2001-10-09 Acumed, Inc. System for fusing joints
FR2739151A1 (en) * 1995-09-22 1997-03-28 Numedic Fixing screw for bone implants
US8480717B2 (en) 1997-02-11 2013-07-09 Warsaw Orthopedic, Inc. Orthopedic implant with locking element
US8641743B2 (en) 1997-02-11 2014-02-04 Warsaw Orthopedic, Inc. Orthopedic implant with locking element
US8262708B2 (en) 1997-02-11 2012-09-11 Warsaw Orthopedic, Inc. Single-lock plating system
EP1393689A3 (en) * 1997-02-11 2004-03-17 MICHELSON, Gary Karlin Anterior cervical plating system and bone screw
US8048075B2 (en) 1997-02-11 2011-11-01 Warsaw Orthopedic, Inc. Orthopedic implant with locking element
US7077844B2 (en) 1997-02-11 2006-07-18 Sdgi Holdings, Inc. Segmentable skeletal plating system
US7074221B2 (en) 1997-02-11 2006-07-11 Sdgi Holdings, Inc. Anterior cervical plate system
US6969390B2 (en) 1997-02-11 2005-11-29 Michelson Gary K Anterior cervical plating system and bone screw
US6916320B2 (en) 1997-02-11 2005-07-12 Gary K. Michelson Anterior cervical plate system
US6926718B1 (en) 1997-02-11 2005-08-09 Gary K. Michelson Multilock anterior cervical plating system
US6936051B2 (en) 1997-02-11 2005-08-30 Gary K. Michelson Multilock anterior cervical plating system
US6936050B2 (en) 1997-02-11 2005-08-30 Gary K. Michelson Multilock anterior cervical plating system
US7137984B2 (en) 1997-02-11 2006-11-21 Warsaw Orthopedic, Inc. Single-lock anterior cervical plate and method
EP1393689A2 (en) * 1997-02-11 2004-03-03 MICHELSON, Gary Karlin Anterior cervical plating system and bone screw
WO2000032125A1 (en) * 1998-11-26 2000-06-08 Synthes Ag Chur Screw
US6030162A (en) * 1998-12-18 2000-02-29 Acumed, Inc. Axial tension screw
US7578836B2 (en) 2000-04-04 2009-08-25 Depuy Mitek Orthopedic screw and method
US6468277B1 (en) 2000-04-04 2002-10-22 Ethicon, Inc. Orthopedic screw and method
US6527777B2 (en) 2000-04-04 2003-03-04 Ethicon, Inc. Device for repairing a soft-tissue tear and method
US6989014B2 (en) 2000-04-04 2006-01-24 Ethicon, Inc. Orthopedic screw and method
US6875215B2 (en) * 2002-02-15 2005-04-05 John Stanley Taras Distraction pin for fracture fixation
WO2004086991A1 (en) 2003-04-03 2004-10-14 Stratec Medical Ag Bone screw
US7641656B2 (en) 2003-09-17 2010-01-05 Corin Limited Prosthetic cup
GB2406056B (en) * 2003-09-17 2007-07-11 Corin Ltd Prosthetic cup
GB2406056A (en) * 2003-09-17 2005-03-23 Corin Ltd Bone tapping kit, fixation member and prosthetic cup
WO2005058175A1 (en) 2003-12-19 2005-06-30 Depuy International Limited A bone screw
EP2898843A2 (en) 2009-11-09 2015-07-29 Spinewelding AG Medical device, apparatus, and surgical method
US8974506B2 (en) 2009-11-09 2015-03-10 Spinewelding Ag Medical device, apparatus, and surgical method
US10342587B2 (en) 2009-11-09 2019-07-09 Spinewelding Ag Medical device, apparatus, and surgical method
US9566099B2 (en) 2009-11-09 2017-02-14 Spinewelding Ag Medical device, apparatus, and surgical method
EP3141202A1 (en) 2009-11-09 2017-03-15 Spinewelding AG Medical device, apparatus
EP2910207A1 (en) 2009-11-09 2015-08-26 Spinewelding AG Medical device, apparatus
US10335216B2 (en) 2011-07-15 2019-07-02 Globus Medical, Inc. Screw implants for bone fusion

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