GB2320197A - Fixing screw for fixing an atlas and an axis - Google Patents

Fixing screw for fixing an atlas and an axis Download PDF

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Publication number
GB2320197A
GB2320197A GB9726342A GB9726342A GB2320197A GB 2320197 A GB2320197 A GB 2320197A GB 9726342 A GB9726342 A GB 9726342A GB 9726342 A GB9726342 A GB 9726342A GB 2320197 A GB2320197 A GB 2320197A
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GB
United Kingdom
Prior art keywords
screw
atlas
axis
fixing
screw member
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Withdrawn
Application number
GB9726342A
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GB9726342D0 (en
Inventor
Yasuaki Tokuhashi
Satoshi Ojima
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Pentax Corp
Original Assignee
Asahi Kogaku Kogyo Co Ltd
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Filing date
Publication date
Application filed by Asahi Kogaku Kogyo Co Ltd filed Critical Asahi Kogaku Kogyo Co Ltd
Publication of GB9726342D0 publication Critical patent/GB9726342D0/en
Publication of GB2320197A publication Critical patent/GB2320197A/en
Withdrawn legal-status Critical Current

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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
    • 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
    • A61B17/70—Spinal positioners or stabilisers ; Bone stabilisers comprising fluid filler in an implant
    • 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
    • A61B17/8645—Headless screws, e.g. ligament interference screws
    • 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
    • A61B17/70—Spinal positioners or stabilisers ; Bone stabilisers comprising fluid filler in an implant
    • A61B17/7047—Clamps comprising opposed elements which grasp one vertebra between them
    • 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
    • A61B17/863—Shanks, i.e. parts contacting bone tissue with thread interrupted or changing its form along shank, other than constant taper
    • 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
    • A61B17/8635—Tips of screws
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS 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
    • A61F2/00—Filters 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
    • A61F2/02—Prostheses implantable into the body
    • A61F2/30—Joints
    • A61F2/44—Joints for the spine, e.g. vertebrae, spinal discs
    • A61F2/442—Intervertebral or spinal discs, e.g. resilient
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS 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
    • A61F2/00—Filters 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
    • A61F2/02—Prostheses implantable into the body
    • A61F2/30—Joints
    • A61F2002/30001—Additional features of subject-matter classified in A61F2/28, A61F2/30 and subgroups thereof
    • A61F2002/30108—Shapes
    • A61F2002/3011—Cross-sections or two-dimensional shapes
    • A61F2002/30138—Convex polygonal shapes
    • A61F2002/30143—Convex polygonal shapes hexagonal
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS 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
    • A61F2/00—Filters 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
    • A61F2/02—Prostheses implantable into the body
    • A61F2/30—Joints
    • A61F2/30767—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
    • A61F2/30771—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth applied in original prostheses, e.g. holes or grooves
    • A61F2002/30772—Apertures or holes, e.g. of circular cross section
    • A61F2002/3079—Stepped or enlarged apertures, e.g. having discrete diameter changes
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS 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
    • A61F2/00—Filters 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
    • A61F2/02—Prostheses implantable into the body
    • A61F2/30—Joints
    • A61F2/30767—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
    • A61F2/30771—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth applied in original prostheses, e.g. holes or grooves
    • A61F2002/3085—Special external or bone-contacting surface, 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
    • A61F2002/30861—Special external or bone-contacting surface, 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
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS 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
    • A61F2/00—Filters 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
    • A61F2/02—Prostheses implantable into the body
    • A61F2/30—Joints
    • A61F2/30767—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
    • A61F2/30771—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth applied in original prostheses, e.g. holes or grooves
    • A61F2002/3085—Special external or bone-contacting surface, 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
    • A61F2002/30863—Special external or bone-contacting surface, 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 the entry end surface having flutes, relief grooves, starter notches or bevelled indentations
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS 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
    • A61F2230/00—Geometry of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
    • A61F2230/0002—Two-dimensional shapes, e.g. cross-sections
    • A61F2230/0017—Angular shapes

Abstract

A fixing screw (1) for fixing an atlas and an axis is made of a self tapping screw which has a blunt point (15) with two flutes (14) and a thread portion. The fixing screw is inserted into a intervertebral part of an atlas and an axis using a guide wire so that the fixing screw engages the surfaces of the atlas and the axis thereby to fix the atlas and the axis. Dimensions of the fixing screw are selected so that the fixing screw securely engages the atlas and the axis and so that the fixing screw does not protrude from the intervertebral part; a clamp comprising a pair of U-shaped hooks 31 for preventing relative movement of the axis and atlas.

Description

2320197 1 FIXING SCREW FOR FIXING ATLAS AND AXIS The present invention
relates to a device for f ixing an atlas (a f irst cervical vertebra) and an axis (a second cervical vertebra) which are dislocated due to subluxation or the like.
In the case where an atlas and an axis are dislocated due to subluxation or the like, the atlas and the axis must be fixed together so as to prevent the relative rotation and relative movement of the atlas and the axis with respect to each other.
A bone transplant method and Magerl method are known as a method for fixing the atlas and the axis. In the bone transplant method, the atlas and the axis are tightened by wires, with a transplant bone interposed between the atlas and the axis. In the Magerl method, a long screw is threaded,-nto the atlas and the axis so that the screw completely penetrates both the atlas and the axis. However, the bone transplant method necessitates extra surgery to obtain 2 a bone to be transplanted whereas the Magerl method is a complex operation since the screw must be carefully threaded so as not to touch blood vessels or nerves around the atlas and the axis.
In order to eliminate the need for extra surgery and to simplify the fixing operation, a recently proposed method uses a clamp device which clamps the atlas and the axis together. However, although the clamp device applies a thrust force to the atlas and the axis, the thrust force is not effective to prevent the relative rotation of the atlas and the axis with respect to each other.
It is therefore an object of the present invention to provide an improved device for fixing an atlas and an axis, which prevents the relative rotation of the atlas and the axis with respect to each other.
According to one aspect of the present invention is provided a fixing screw including can be threaded into an intervertebral and an axis. The threading direction plane of the inter-vertebral part. The the surfaces of the atlas the relative movement of the atlas and the there a screw member which part between an atlas is in narallel to a screw member engages and the axis, thereby to prevent axis (with 3 respect to each other) in the plane of the inter-vertebral part.
Thus, by inserting two screw member into the right and left intervertebral parts, the relative rotation of the atlas and the axis is effectively prevented. When the screw member is used along with a clamp device which clamps the atlas and the axis together, the atlas and the axis are securely fixed with each other.
In a particular arrangement, the total length of the screw member is set in a range of 4 mm to 12 mm, so that the screw member does not protrude from the intervertebral part in a state that the screw member is inserted therein. Further, it is preferred that the outer diameter of the screw member is set in the range of 4 mm to 7 mm, and the minor diameter of the screw member is set in the range of 3 mm to 5 mm. With such an arrangement, the screw member (inserted in the intervertebral part) securely engages both the atlas and the axis.
Optionally, the screw member may be a hexagon-socketset-screw which has no head and has a hexagon socket. Since the screw member has no head, the screw member can be fully inserted in the intervertebral part. Further, since the screw member has a hexagon socket, the screw member can be remotely rotated by a hexagon rod spanner or the like. Further, it is oreferable that the screw member is a self 4 tapping screw which has a blunt point with at least one flute and threads, enabling easy threading operation.
Further, it is preferable that the screw member is provided with a center hole which axially penetrates the screw member. With this, prior to the insertion of the screw member, a guide wire can be inserted into the interve-rtebral part for leading the screw to the intervertebral part. Furthermore, it is possible that the screw member is constructed such that a thread groove thereof has a circular shape, so that the screw member can easily engage the atlas and the axis. The screw member can be made of a titanium alloy, which has good biological affinity for a human body.
According to another aspect of the present invention there is provided a fixing system including at least one screw member and at least one clamp device which clams the atlas and the axis together. The clamp device prevents the relative movement of the atlas and the axis with respect to each other in the thrust direction, wInile the screw member prevents the relative rotation of the atlas and the axis with respect to each other.
An example of the present invention will now be described with reference to the accompanying drawings, which:- Fig. 1 is a perspective view showing a fixing screw embodying the present invention along with an atlas and an axis; Fig. 2 Fig - 1; Fig. 3 is a side view of the fixing screw of Fig. 1; Fig. 4 is a front view of the fixing screw of Fig. 1; Fig. 5 is a sectional view of the fixing screw inserted into an intervertebral part between the atlas and the axis; Fig. 6 is a rear elevation showing the fixing screw inserted into the intervertebral part; and Figs. 7A, 7B and 7C are sectional views showing an inserting operation of the fixing screw into the intervertebral part.
is a perspective view of the fixing screw of Fig. 1 is a perspective view showing a f ixing screw 1 of the present invention along with an atlas (the first cervical vertebra) 5 and an axis (the second cervical vertebra) 6. Intervertebral parts 55 are formed between the atlas 5 and the axis 6. The intervertebral parts are positioned at left side and right side with respect to a rotation center 0 of the human body (the right intervertebral part 55 is not shown in Fig. 1). The fixing screw 1 is horizontally inserted into the intervertebral part 55 from the rear side of the human body.
6 Figs. 2, 3 and 4 are a perspective view, a side view and a front view of the fixing screw 1, respectively. The fixing screw 1 is a so-called self tapping screw which has a blunt point 13 with two f lutes 14 and a thread portion 12. When the f ixing screw 1 is screwed into the intervertebral part 55, a leading part (the blunt point 13 and the f lutes 14) cuts into the surfaces of the atlas 5 and the axis 6. so that the thread portion 12 taps the surfaces of the atlas 5 and the axis 6.
The fixing screw 1 is also a so-called hexagonsocketset-screw which has no head and has a hexagon socket 11. Since the f ixing screw 1 has no head, the fixing screw 1 can be fully inserted in the intervertebral part 55 without protruding therefrom. Since the fixing screw 1 has the hexagon socket 11, the fixing screw 1 can be remotely operated by a not shown hexagon rod spanner. A center hole 15 is formed at the center of the fixing screw 1 which axially penetrates throughout the fixing screw 1. The center hole 15 is provided for inserting a guide wire (described below). The fixing screw 1 is made of a titanium alloy which has good biological affinity for a human body.
Fig. 5 is a sectional view showing the f ixing screw 1 inserted into the inter--,,,.ertebral part 55. In a human body, the width H of the intervertebral parz 55 in the frontward and rearward direction is generally 20 =. Thus, the total 7 length L (Fig. 3) of the f ixing screw 1 is set in the range of 4 mm to 12 mm so that the f ixing screw 1 is conLpletely inserted into the intervertebral part 55 without protruding therefrom. Further, the interval D between the atlas 5 and the axis 6 is generally 2 mm. Thus, the outer diameter A (Fig. 3) of the thread portion 12 is set within the range of 4 mm to 7 mm and the minor diameter B (Fig. 3) of the thread portion 12 is set in the range of 3 mm to 5 im, so that the thread portion 12 of the fixing screw 1 securely engages the surfaces of the atlas 5 and the axis 6.
Several combinations of the dimensions of the fixing screw 1 are provided to cover the individual difference of the size of the intervertebral part 55. Table 1 shows examples of the combination of the dimensions of the fixing screw 1. It is possible to provide any other combination as long as the total length L, the outer diameter A, and the minor diameter B are respectively in the ranges above described.
Table 1 L (mm) 8.0 8.0 10.0 10.0 A (mm) 5.0 5.5 6.0 6.5 B (mm) 3.5 3.5 4.0 4.5 8 Since the thread portion 12 of the fixing screw 1 (inserted into the intervertebral part 55) engages the surfaces of the atlas 5 and the axis 6, the atlas 5 and the axis 6 do not relatively move with each other in a plane of the intervertebral part 55 (particularly, in the frontward or rearward direction). Thus, when two fixing screws 1 are respectively inserted into the left and right intervertebral parts 55 as shown in Fig. 6, the atlas 5 and the axis 6 do not relatively rotate as shown by an arrow R. In Fig. 6 the fixing screws 1 are shown by dash-lines.
As shown in Figs. 5 and 6, the f ixing screw 1 is used along with a clamp device 3. The clamp device 3 includes two U-shaped hooks 31 and 32 facing with each other, and the space between the hooks 31 and 32 can be adjusted by an adjustment screw 33. The hooks 31 and 32 are hung onto archshaped parts (vertebral arches) 52 and 62 of the atlas 5 and the axis 6 respectively. By reducing the spacing between the hooks 31 and 32 (using the adjustment screw 33), the atlas 5 and the axis 6 can be vertically clamped together. As constructed above, the atlas 5 and the axis 6 are steadily fixed by the fixing screw 1 and the clamp. device 3 such that the atlas 5 and the axis 6 do not relatively -rotate and relatively move (in the thrust direction) with respect to each other.
9 A method for inserting the fixing screw 1 into the intervertebral part 55 is described with reference to Figs. 7A through 7C. First, as shown in Fig. 7A, a guide wire 41 is inserted into the intervertebral part 55. After the guide wire 41 is inserted into the intervertebral part 55, as shown in Fig. 7B, a drill 42 is inserted along the guide wire 41. The drill 42 is provided with a center hole through which the guide wire 41 penetrates. The drill 42 is rotated to cut a prepared hole in the intervertebral part 55. Then, as shown in Fig. 7C, the fixing screw 1 is inserted into the prepared hole 58 formed by the drill 42. The guide wire 41 penetrates the center hole 15 (Fig. 3) of the f ixing screw 1, which leads the f ixing screw 1 to the inter-vertebral part 55. The fixing screw 1 is axially urged and rotated by a hexagon rod spanner 45 which fits into the hexagon socket 11 (Fig. 2) of the fixing screw 1. The hexagon rod spanner 45 is also provided with a center hole through which the guide wire 41 penetrates, so that the hexagon rod spanner 45 is guided by the guide wire 41. Since the fixing screw 1 is a self tapping screw, the fixing screw 1 cuts the inner surface of the prepared hole 58 (surfaces of the atlas 5 and the axis 6) and is threaded into the prepared hole 58. Since the thread groove of the thread portion 12 has a semicircular shape as indicated by "r" in Fig. 3, the outer edge of the thread portion 12 has an acute angle. Therefore, the thread portion 12 can easily be threaded into the inner surface of the prepared hole 58.
After the fixing screw 1 is threaded in the intervertebral part 55, the guide wire 41 is removed from the intervertebral part 55, which completes the inserting operation of the fixing screw 1. The clamp device 3 (Fig. 6) is attached to the atlas 5 and the axis 6 after the fixing screw 1 is inserted into the intervertebral part 55. The explanation of the clamping operation is omitted.
As described above, with this embodiment, the atlas 5 and the axis 6 can be f ixed such that the atlas 5 and the axis 6 do not relatively rotate with respect to each other and that the atlas 5 and the axis do not relatively move (in the thrust direction) with respect to each other.
Furthermore, since the fixing screw 1 does not protrude from the intervertebral part 55, the fixing screw 1 does not interfere with another tissue or the like.
Although the structure of a fixing screw is described herein with respect to the preferred e:-,=d-Jment, many modifications and changes can be made. .
- 10 11

Claims (1)

  1. CLAIMS:
    A fixing screw for fixing an atlas and an axis, said fixing screw comprising; a screw member which can be threaded into an inter-vertebral part between said atlas and said axis, the threading direction thereof being in parallel to a plane of said inter-vertebral part, said screw member cutting and engaging the surfaces of said atlas and said axis at said inter-vertebral part, thereby to prevent the relative movement of said atlas and said axis with respect to each other in said plane of said intervertebral part.
    2. A f ixing screw according to claim 1 wherein the total length of said screw member is set in the range of 4 mm to 12 mm, so that the screw member does not protrude from the intervertebral part.
    3. A fixing screw according to claim 1 or 2 wherein the outer diameter of said screw member is set in the range of 4 mm to 7 mm.
    12 4. A fixing screw according to claim 3 wherein a minor diameter of the fixing screw is set in the range of 3 mm to 5 MIn.
    5. A f ixing screw according to any preceding claim wherein said screw member has no head so that said screw member can be fully inserted in said intervertebral part.
    6. A f ixing screw according to any preceding claim wherein said screw member has a hexagon socket so that said screw member can be remotely operated.
    7. A f ixing screw according to any preceding claim wherein said screw member is a self tapping screw.
    8. A f ixing screw according to claim 7 wherein said self tapping screw has a blunt point with at least one f lute and threads.
    9. A fixing screw according to claim 7 or 8 wherein a thread groove of said screw member has a semicircular shape.
    10. A f ixing screw according to any preceding claim, wherein said screw member is made of a titanium alloy.
    13 11. A f ixing screw according to any preceding claim, wherein said screw member is provided with a center hole which penetrates said screw member in the longitudinal direction thereof.
    12. A fixing system for fixing an atlas and an axis, said fixing screw comprising: at least one screw member which can be threaded into an intervertebral part between said atlas and said axis, said screw member engaging the surfaces of said atlas and said axis at said intervertebral part; and at least one clamp device which clamps said atlas and said axis together, wherein said screw member 1Drevents the relative rotation of said atlas and said axis with respect to each other, and wherein said clamp device prevents the relative movement of said atlas and said ax--s with respect to each other in the thrust direction.
    14 13. A f ixing system according to claim 12 wherein said clamp device includes a pair of U-shaped hooks, said U-shaped hooks being hung onto arch-shaped parts of said atlas and said axis.
    14. An orthopaedic screw for fixing an atlas and an axis, the screw comprising: a screw member provided with a hole along the longitudinal length thereof and having a cutting and engaging surface.
    15. A screw according to claim 14 comprising an atlas and axis fixing screw.
    16. A fixing screw for fixing an atlas and an axis substantially as described with reference to the drawings.
GB9726342A 1996-12-12 1997-12-12 Fixing screw for fixing an atlas and an axis Withdrawn GB2320197A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP8352226A JPH10165412A (en) 1996-12-12 1996-12-12 Spacer for atlas and axis fixing

Publications (2)

Publication Number Publication Date
GB9726342D0 GB9726342D0 (en) 1998-02-11
GB2320197A true GB2320197A (en) 1998-06-17

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GB9726342A Withdrawn GB2320197A (en) 1996-12-12 1997-12-12 Fixing screw for fixing an atlas and an axis

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JP (1) JPH10165412A (en)
DE (1) DE19755369A1 (en)
FR (1) FR2757041A1 (en)
GB (1) GB2320197A (en)

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CN102860863A (en) * 2011-07-09 2013-01-09 李郁松 Fixing device in atlantoaxial anterior
CN104586546A (en) * 2015-01-21 2015-05-06 王琪 Screwed type fusion apparatus among cervical vertebra zygopophysis joints and supporting cutter of fusion apparatus

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AU778410B2 (en) * 1999-12-01 2004-12-02 Henry Graf Intervertebral stabilising device
JP4755782B2 (en) * 2001-08-01 2011-08-24 昭和医科工業株式会社 Bone implant implant
JP2003038507A (en) * 2001-08-01 2003-02-12 Showa Ika Kohgyo Co Ltd Implant for bone joining implement
JP2003325536A (en) * 2002-05-09 2003-11-18 Showa Ika Kohgyo Co Ltd Implant screw
AU2005295589B2 (en) * 2004-10-15 2009-12-03 Baxano, Inc. Devices and methods for tissue removal
US7578819B2 (en) * 2005-05-16 2009-08-25 Baxano, Inc. Spinal access and neural localization
US7828828B2 (en) * 2005-04-14 2010-11-09 Warsaw Orthopedic, Inc Intervertebral joint
WO2015187937A1 (en) 2014-06-04 2015-12-10 Wenzel Spine, Inc. Bilaterally expanding intervertebral body fusion device
CN106974715A (en) * 2017-03-31 2017-07-25 张银顺 A kind of Study of Atlas Fracture by Finite fixator
US11219531B2 (en) 2019-04-10 2022-01-11 Wenzel Spine, Inc. Rotatable intervertebral spacing implant
US20230073858A1 (en) * 2021-09-09 2023-03-09 Truspine Technologies Limited Non-intrusive bone anchor for use on vertebral laminar processes

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EP0674880A1 (en) * 1994-03-29 1995-10-04 Andreas C. Dr. med. Stähelin Biodegradable osteosynthesis screw and corresponding screwdriver

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US5334204A (en) * 1992-08-03 1994-08-02 Ace Medical Company Fixation screw
US5443509A (en) * 1992-12-10 1995-08-22 Linvatec Corporation Interference bone-fixation screw with multiple interleaved threads
EP0669110A2 (en) * 1994-02-14 1995-08-30 SMITH & NEPHEW DYONICS INC Interference screw having a double tapered root
EP0674880A1 (en) * 1994-03-29 1995-10-04 Andreas C. Dr. med. Stähelin Biodegradable osteosynthesis screw and corresponding screwdriver

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6689168B2 (en) * 2000-10-05 2004-02-10 The Cleveland Clinic Foundation Method and apparatus for stabilizing adjacent bones
CN102860863A (en) * 2011-07-09 2013-01-09 李郁松 Fixing device in atlantoaxial anterior
CN104586546A (en) * 2015-01-21 2015-05-06 王琪 Screwed type fusion apparatus among cervical vertebra zygopophysis joints and supporting cutter of fusion apparatus

Also Published As

Publication number Publication date
GB9726342D0 (en) 1998-02-11
JPH10165412A (en) 1998-06-23
FR2757041A1 (en) 1998-06-19
DE19755369A1 (en) 1998-06-18

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