JP2016195692A - Screw structure to be used for bone, and screw and tap including structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screw structure capable of performing a work simply and safely to a bone of an organism represented by a bone of a human being.SOLUTION: In a screw structure for a bone including a screw tip 10, a screw thread 20 formed spirally, and a thread groove 30 formed between facing screw threads, the screw tip is positioned approximately on a screw axis A-A, a point angle of the screw tip is in the range of 40±2 degrees, and the maximum height of the first screw thread part 21 positioned 1/4 pitch backward from the screw tip along the screw thread is in the range of 0.20±0.02 mm.SELECTED DRAWING: Figure 2

Description

   The present invention relates to a screw structure for use in biological bones, and in particular, to a screw structure for use in human bones and screws and taps with such structure.

Various screw structures have been proposed so far.
As a structure that can be easily screwed into a material that does not have screw holes, the screw threads are closely arranged at the tip of the screw, and the threads are equally spaced at the rear end of the screw. The arrange | positioned 1st screw is proposed (patent document 1).
If it is this 1st screw, it will be said that the fiber of wood can be prevented from jumping out from the wood when screwing in while rotating the screw with respect to the wood.

On the other hand, as a different structure that can be screwed in while rotating the screw easily with respect to a material in which no screw hole is formed, the cross-sectional shape of the thread is rounded at the screw tip part with respect to the vertical cross section with respect to the screw shaft. There has also been proposed a second screw having a triangular shape in which the cross-sectional shape of the screw thread changes into a circle from the front end portion of the screw to the rear end portion of the screw (Patent Document 2).
With this second screw, a screw hole can be formed in the material relatively easily, and it is possible to prevent the thread from being broken by the material.

JP 2012-72840 A Japanese Patent Publication No. 6-60652

By the way, when the present inventors examined the structure of a screw used for a living bone, particularly a human bone, a screw having a known screw structure cannot easily form a screw hole in the bone. I noticed.
In particular, in the case of bones typified by human skulls, it is not easy to form screw holes in the bone because the bone thickness is small and the strength of the bone changes in the bone thickness direction.
In addition, there may be important tissue inside the bone on the opposite side of the bone that the screw contacts.
If it is not easy to form a screw hole in the bone, a relatively large force is often applied to the vertical direction of the bone surface when forming the screw hole.
However, if a screw thread destroys the internal structure of the screw hole during the process of screwing the screw into the bone, the screw can penetrate into the bone vigorously, which can damage important tissue in the bone. There is also sex.
As you can see, in the case of screws used for living bones, it is not enough to simply screw them into the bones, and it is safe for the practitioner to work when forming screw holes in human bones. It is also required to be controllable.

  An object of the present invention is to provide a screw structure that can easily and safely work on a bone of a living body represented by a human bone.

  As a result of intensive studies by the inventor to solve the above-mentioned problems, the tip angle of the screw tip is in the range of 40 ± 2 degrees, and the first screw thread portion at the 1/4 pitch rearward from the screw tip along the screw thread. It has been found that a screw structure for bone having a maximum height of 0.20 ± 0.02 mm in the range solves the above problems, and has completed the present invention.

That is, the present invention
[1] A screw tip, a screw thread formed in a spiral shape, and a screw groove formed between the opposing screw threads,
The screw tip is substantially on the screw axis;
The tip angle of the screw tip is in the range of 40 ± 2 degrees;
The bone screw structure, wherein a maximum height of a first thread portion located at a quarter pitch rearward from the screw tip along the thread is in a range of 0.20 ± 0.02 mm. Is to provide.

One of the present invention is
[2] The first screw groove is located in front of the second screw thread located at 3/4 pitch rearward along the screw thread from the screw tip,
The deepest part of the first thread groove is located closest to the screw axis among the first thread grooves,
The bone screw structure according to the above [1], wherein an angle between a tangent drawn from the screw tip to the deepest portion of the first screw groove and a screw axis is in a range of 0 to 3.0 degrees. is there.

One of the present invention is
[3] The first screw thread portion is located at a quarter pitch rearward from the screw tip along the screw thread,
A second threaded portion is positioned 3/4 pitch rearward from the threaded tip along the thread;
An angle between a first tangent to the first thread drawn from the screw tip and a second tangent to the second thread drawn from the screw tip is in a range of 40 ± 2 degrees. And
The bone screw structure according to the above [1] or [2], wherein all screw threads are inside the first tangent line and the second tangent line.

One of the present invention is
[4] The (2n + 2) screw thread portion is defined as a (2n + 2) screw thread portion that is located one pitch rearward along the screw thread from the (2n) screw thread portion on the screw thread. When the thread portion located one pitch back along the thread from the second (2n + 4) thread portion,
When n is 2, the (2n) thread portion is located one pitch rearward from the second thread portion along the thread,
n is any integer from 2 to 20,
The distance between the (2n) thread portion and the (2n + 2) thread portion is
An interval between the (2n + 2) th thread portion and the (2n + 4) th thread portion;
The bone screw structure according to any one of the above [1] to [3], which is substantially the same on the basis of the screw axis direction.

One of the present invention is
[5] n is any integer from 2 to 20, and the height of the (2n) thread portion and the height of the (2n + 2) thread portion are perpendicular to the screw axis. The bone screw structure according to the above [4], which is substantially the same as a reference, is provided.

One of the present invention is
[6] A bone screw comprising the bone screw structure according to any one of [1] to [5] is provided.

One of the present invention is
[7] A bone tap including the bone screw structure according to any one of [1] to [5] is provided.

In the screw structure of the present invention, the tip angle of the screw tip is in the range of 40 ± 2 degrees, and the maximum height of the first screw thread portion behind the 1/4 pitch along the screw thread from the screw tip is 0.20. The range is ± 0.02 mm.
By providing this screw structure, the screw structure of the present invention can easily and safely make a screw hole in a living bone represented by a human bone, and form the screw structure in the screw hole.

FIG. 1 is a schematic diagram for explaining a screw structure according to the first embodiment. FIG. 2 is a partially enlarged schematic view for explaining the screw structure according to the first embodiment. FIG. 3 is a partially enlarged schematic view for explaining the feature of the tip structure in the screw structure 100. FIG. 4 is a partially enlarged schematic diagram for explaining the relationship between the pitches of the thread portions in the screw structure 100. FIG. 5 is a partially enlarged schematic view for explaining the screw structure 110. FIG. 6 is a schematic diagram for explaining the screw structure 120. FIG. 7 is a schematic diagram for explaining the bone tap 300 according to the fourth embodiment. FIG. 8 is a schematic diagram for explaining the bone screw 400 according to the fifth embodiment.

  The screw structure of the present invention will be described below based on examples with reference to the drawings. In addition, the content of this invention is not limited at all by the present Example.

FIG. 1 is a schematic diagram for explaining a screw structure according to the first embodiment.
As shown in FIG. 1, the screw structure 100 according to the first embodiment is formed of a main body 1, a neck 2, and a screw 3.
FIG. 2 is a partially enlarged schematic view for explaining the screw structure according to the first embodiment.
As shown in FIG. 2, the screw portion 3 of the screw structure 100 is formed between a screw tip 10, a screw thread 20 formed in a spiral shape along the screw axis, and an opposing screw thread. And a thread groove 30.
In the case of Example 1, the screw thread 20 is formed from the screw tip 10, but the screw thread in the present invention is preferably formed starting from a range of 0 to 3 mm from the screw tip 10.
A dashed line AA in FIG. 2 is a screw axis of the screw structure 100. In the present invention, the screw tip 10 is substantially on the screw axis.
Here, the meaning of being substantially on the screw axis includes the case where the screw tip 10 is on the screw axis and the case where the screw tip 10 is within a range of plus or minus 2.0 mm in the vertical direction from the screw axis. The range is preferably within a range of plus or minus 1.0 mm, and more preferably within plus or minus 0.5 mm.
Further, for convenience of explanation, in the present invention, in the screw structure 100, the side where the screw tip 10 is located is the front of the screw structure 100, and the side opposite to the side where the screw tip 10 is located is the rear.
A point advanced from the screw tip 10 to the rear by a quarter pitch along the screw thread 20 is the first screw thread portion 21.
A point advanced from the first screw thread portion 21 by ½ pitch is a second screw thread portion 22. A point advanced from the second screw thread portion 22 1/2 pitch backward is a third screw thread portion 23. Similarly, a point advanced from the third screw thread portion 23 by 1/2 pitch is a fourth screw thread portion 24.
The same applies to the fifth thread portion 25 to the eighth thread portion 28.

Here, the point advanced backward by 1/4 pitch means that the screw shaft portion of the screw structure of the present invention has a screw thread portion around the screw axis along the spiral screw thread. It is the point located in the place where it advances backward.
Similarly, the point advanced backward by 1/2 pitch means that the screw shaft of the screw structure of the present invention is advanced backward by 1/2 turn around the screw axis along the screw thread. A point located at a certain point.

  As shown in FIG. 2, the screw groove 30 of the screw structure 100 is formed between the opposing screw threads 20, 20 among the screw threads 20 formed in a spiral shape along the screw axis.

FIG. 3 is a partially enlarged schematic view for explaining the tip structure in the screw structure 100.
Of the screw grooves 30, the first screw groove portion 31 is formed in front of the second screw thread portion 22, and the first screw groove end portion 31a and the first screw groove end portion 31b are respectively formed. This corresponds to the end of the first screw groove 31.
The second screw groove portion 32 is formed between the first screw thread portion 21 and the third screw thread portion 23, and the second screw groove end portion 32a and the second screw groove end portion 32b. Respectively correspond to the end portions of the second thread groove portion 32.
Similarly, the third screw groove portion 33 is formed between the second screw thread portion 22 and the fourth screw thread portion 24, and the third screw groove end portion 33a and the third screw groove end portion. 33b corresponds to the end of the third screw groove 33, respectively.

Of the tip portion 10a of the screw tip 10 of the screw structure 100, the front of the first screw groove end portion 31a has a conical shape, and a projected image with respect to a plane parallel to the screw axis is a sharp triangle (not shown). It has a structure that becomes.
The broken line a and the broken line b in FIG. 3 intersect each other at the same angle as the tip angle of the sharp triangle, that is, the same as the tip angle θ of the tip portion 10a, starting from the screw tip 10.
The angle between the broken line a and the broken line b is in the range of 40 ± 2 degrees. If the tip angle θ is in the range of 40 ± 2 degrees, the tip 10a of the screw structure 100 is relatively easily and safely contacted with the living bone while rotating the screw structure 100. In contrast, it is possible to enter the bone while forming a screw hole.
When the tip angle θ is less than 38 degrees or exceeds 42 degrees, it is difficult to form a screw hole in the bone of a living organism even if the screw structure 100 is rotated.

Further, the value of the tip angle θ is a broken line b that is a first contact with the first screw thread portion 21 from the screw tip 10 and a second value that is in contact with the second screw thread portion 22 from the screw tip 10. It is also preferable to apply to the broken line a which is a close battle.
It is preferable that the angle of the broken line a and the broken line b which contact | connects the said thread part 21 and the said thread part 22, respectively is the range of 40 +/- 2 degree.
If the angle of the broken line a and the broken line b that contact the screw thread part 21 and the screw thread part 22, respectively, is in the range of 40 ± 2 degrees, the screw structure 100 is rotated and brought into contact with a living bone, The distal end portion 10a of the screw structure 100 can be relatively easily and safely allowed to enter the inside of the bone while forming a screw hole in the living bone.

  It is preferable that all the screw threads in the present invention are inside the broken lines a and b with respect to the screw axis.

Next, the height of the first screw thread portion 21 is in a range of 0.20 ± 0.02 mm from the screw axis with respect to the direction perpendicular to the screw axis.
When the height of the first screw thread portion 21 is 0.18 mm or more, damage to the tip portion 10a due to a decrease in strength of the tip portion 10a of the screw tip 10 can be avoided.
When the height of the first screw thread portion 21 is 0.22 mm or less, when the screw structure 100 is rotated and brought into contact with a living bone, the distal end portion 10a of the screw structure 100 is a bone. Enter the interior smoothly.

  FIG. 4 is a partially enlarged schematic diagram for explaining the relationship between the pitches of the thread portions in the screw structure 100.

A pitch x for one rotation of the second screw thread portion 22 and the fourth screw thread portion 24, and a rotation for one rotation of the fourth screw thread portion 24 and the sixth screw thread portion 26. The pitch y is substantially the same.
Here, the pitch for one rotation is substantially the same means a range in which the interval between adjacent screw thread portions is within plus or minus 2 mm with reference to the direction parallel to the screw axis.
This range is preferably within plus or minus 1 mm, and more preferably within plus or minus 0.5 mm.
By making the screw thread spacing at the rear part of the screw structure 100 substantially the same, it is possible to prevent the screw hole from being broken by the screw thread part when the screw hole is formed in the bone. For this reason, the screw structure 100 can be easily and safely entered into a bone in which a screw hole is not formed more safely.

  In the present invention, it is preferable that the pitch for one rotation is substantially the same for the threaded portion behind the sixth threaded portion 26.

It is preferable that the height of the rear thread portion after the fourth thread portion 24 is substantially the same with respect to the vertical direction of the screw axis.
Here, “substantially identical” means that the distance in the vertical direction from the screw axis is within ± 2 mm.

The second embodiment is a modification of the first embodiment.
In the case of Example 1, the deepest portion 31c of the first screw groove 31 was located on the screw axis.
On the other hand, the second embodiment is different in that the deepest portion 31c of the first screw groove portion is separated from the screw axis.
The rest is the same as in the first embodiment.
Here, the deepest portion of the screw groove portion refers to a portion of the screw groove portion that is closest to the screw axis with respect to a direction perpendicular to the screw axis.
FIG. 5 is an enlarged partial schematic view for explaining the structure of the first screw groove portion of the screw structure according to the second embodiment.
A broken line c is a tangent to the deepest portion 31 c of the first screw groove portion 31 drawn from the screw tip 10 of the screw structure 110 according to the second embodiment.
The angle θ ′ between the tangent line c drawn from the screw tip 10 to the deepest portion 31c of the first screw groove 31 and the screw axis is preferably in the range of 0 to 3.0 degrees.
If the angle θ ′ between the tangent and the screw axis is in the range of 0 to 3.0 degrees, the strength of the tip portion 10a of the screw tip 10 of the screw structure 110 can be kept high.

The third embodiment is a modification of the first embodiment.
In the case of the first embodiment, the first to eighth thread portions are present, but in the case of the third embodiment, the first to the fourteenth thread portions are present.
The first to fourteenth thread portions of the screw structure 120 according to the third embodiment correspond to reference numerals 121 to 134, respectively.
Moreover, the thread groove part formed between each opposing screw thread part respond | corresponds to the referential mark 231-243, respectively.

  The screw structure 120 according to the third embodiment is different from the screw structure 100 according to the first embodiment in that the screw tip 10, the first screw thread portion 21, the second screw thread portion 22, and the third screw thread portion. 23, the 1st thread groove part 31, the 2nd thread groove part 32, and the 3rd thread groove part 33 are completely the same.

FIG. 6 is a partially enlarged schematic view for explaining the screw structure 120.
In the case of a structure in which a thread portion further exists behind one pitch of the fourth thread portion 124, the interval of one pitch of each thread portion is substantially the same.
Here, the 1 pitch interval of each thread portion refers to a distance when moving backward along the thread by one rotation with respect to the direction parallel to the screw axis.
In addition, one pitch interval of each thread portion is substantially the same, the one pitch interval between adjacent thread portions is within a range of plus or minus 2 mm with respect to the direction parallel to the screw axis. Say.
This range is preferably within plus or minus 1 mm, and more preferably within plus or minus 0.5 mm.
In the present invention, when n is 2 or more, the 1 pitch interval between the (2n) thread portion and the (2n + 2) thread portion is equal to the (2n + 2) thread portion and (2n + 4). It is preferable that the pitch is substantially the same as the pitch interval of 1 with the threaded portion. n is more preferably an integer of 2 or more and 20 or less.

Further, in the present invention, when n is 2 or more, the height of each thread portion perpendicular to the screw axis is substantially the same for the subsequent thread portions including the 2nth thread portion. Preferably there is.
Here, the phrase “substantially the same for each screw thread portion” refers to a range in which the height of each screw thread portion perpendicular to the screw axis is within ± 2 mm.
This range is preferably within plus or minus 1 mm, and more preferably within plus or minus 0.5 mm.

  By adjusting the screw thread portion behind the screw structure 110 as described above, it is possible to prevent the screw hole from being broken by the screw thread portion when the screw hole is formed in the bone. For this reason, the screw structure 120 can be easily and safely entered into a bone in which a screw hole is not formed more safely.

The fourth embodiment is an application example of the first embodiment.
FIG. 7 is a schematic diagram for explaining the bone tap 300 according to the third embodiment.
A bone tap 300 according to the third embodiment includes a main body 310 instead of the main body 1 of the screw structure 100 used in the first embodiment.
The rest is the same as in the first embodiment.
The main body 310 includes a tool connecting groove 320 and a tool connecting protrusion 330.
The cross section of the instrument connecting protrusion 330 with respect to the direction perpendicular to the screw axis is a regular hexagon, and a rotating device (not shown) that can be fitted to the instrument connecting protrusion 330 is used. The bone tap 300 can be rotated.
In addition, in order to prevent the idling | slipping between rotation apparatuses, the shape of the cross section of the said protrusion part 330 for apparatus connection has a preferable shape other than circular, and if it is a regular polygon, it is more preferable.

  As a material of the bone tap 300, a metal material such as titanium, aluminum, and stainless steel, an inorganic material such as a sintered ceramic, or the like can be used.

The length in the screw axis direction from the screw tip 10 of the bone tap 300 to the rear end of the screw portion 3 is preferably in the range of 2 to 50 mm.
The outer diameter of the threaded portion 3 is preferably in the range of 2 to 20 mm.
The length of the neck 2 in the screw axis direction is preferably in the range of 0.5 to 10 mm.
The length in the screw axis direction from the screw tip 10 to the rear end of the main body 310 is preferably in the range of 20 to 200 mm.

  The structure of the screw part 3 used in the bone tap of the present invention can be modified to the structure of the screw part shown in Example 2 or 3 instead of that shown in Example 4.

  By using the bone tap of the present invention, a screw hole can be easily and safely formed in a living bone represented by a human bone, and a screw structure can be formed in the screw hole.

The fifth embodiment is an application example of the first embodiment.
FIG. 8 is a schematic diagram for explaining the bone screw 400 according to the fifth embodiment.
A bone screw 400 according to the fifth embodiment includes a main body 410 instead of the main body 1 and the neck 2 of the screw structure 100 used in the first embodiment.
The rest is the same as in the first embodiment.
The main body portion 410 includes a conical head portion 420 having a substantially spherical rearward projecting portion and a connecting portion 430.
The cross-sectional shape of the main body 410 with respect to the direction perpendicular to the screw axis is hexagonal, and the bone screw 400 can be installed on the bone by rotating the main body 410 with a finger or the like. it can.
The cross-sectional shape of the main body 410 is preferably other than circular, and more preferably polygonal.
In addition, after the bone screw 400 is installed on the bone, the connecting portion 430 can be cut.

As a material of the bone screw 400, a metal material such as titanium, aluminum, and stainless steel, an inorganic material such as sintered ceramic, and an organic material such as synthetic resin can be used.
The material of the bone screw 400 may be a biodegradable resin that is absorbed in vivo.

The length in the screw axis direction from the screw tip 10 of the bone screw 400 to the rear end of the screw portion 3 is preferably in the range of 2 to 50 mm.
The outer diameter of the threaded portion 3 is preferably in the range of 2 to 20 mm.
The length in the screw axis direction from the screw tip 10 to the rear end of the main body 410 is preferably in the range of 5 to 100 mm.

  The structure of the screw part 3 used for the bone screw 400 of the present invention can be modified to the structure of the screw part or the like shown in Example 2 or 3 instead of that shown in Example 5.

  By using the bone screw of the present invention, a screw hole can be easily and safely formed in a living bone represented by a human bone, and a screw structure can be formed in the screw hole.

   The screw structure for bone according to the present invention can be mass-produced, and is particularly suitable for applications that require bolting to bone parts such as a human skull.

1,310,410 Main body part 2 Neck part 3 Screw part 10 Screw tip 20 Screw thread 21, 121 First thread part 22, 122 Second thread part 23, 123 Third thread part 24, 124 Fourth Thread part 25,125 Fifth thread part 26,126 Sixth thread part 27,127 Seventh thread part 30 Thread groove 31,231 First thread groove part 31a Deepest of first thread groove part Portions 32, 232 Second screw groove portion 32a Deepest portion of second screw groove portion 33, 233 Third screw groove portion 34, 234 Fourth screw groove portion 35, 235 Fifth screw groove portion 36, 236 Sixth screw groove portion 100, 110, 120 Screw structure 128 Eighth thread part 129 Ninth thread part 130 Tenth thread part 131 Eleventh thread part 132 Twelfth thread part 133 Thirteenth screw Yamabe 134 10th Screw thread 237 seventh thread groove 238 eighth thread groove 239 ninth thread groove 240 tenth thread groove 241 eleventh thread groove 242 twelfth thread groove 243 thirteenth thread groove 300 Bone Tap 320 Instrument Connection Groove 330 Instrument Connection Projection 400 Bone Screw 420 Head 430 Connection AA Screw Axis a, b Auxiliary Line for Explaining the Angle of the Tip Angle of the Tip c From the Screw Tip Tangent line drawn at the deepest part of the first thread groove θ Tip angle at the tip θ ′ Angle between tangent c and screw axis

Claims (7)

A screw tip, a screw thread formed in a spiral shape, and a screw groove formed between the opposing screw threads,
The screw tip is substantially on the screw axis;
The tip angle of the screw tip is in the range of 40 ± 2 degrees;
The bone screw structure, wherein a maximum height of a first thread portion located at a quarter pitch rearward from the screw tip along the thread is in a range of 0.20 ± 0.02 mm. . A first thread groove portion is located in front of a second thread portion located 3/4 pitch rearward along the thread from the screw tip;
The deepest part of the first thread groove is located closest to the screw axis among the first thread grooves,
The screw structure according to claim 1, wherein an angle between a tangent drawn from the screw tip to the deepest portion of the first screw groove and a screw axis is in a range of 0 to 3.0 degrees. A first screw thread portion is located a quarter pitch rearward from the screw tip along the screw thread;
A second threaded portion is positioned 3/4 pitch rearward from the threaded tip along the thread;
An angle between a first tangent to the first thread drawn from the screw tip and a second tangent to the second thread drawn from the screw tip is in a range of 40 ± 2 degrees. And
The screw structure according to claim 1 or 2, wherein all screw threads are inside the first tangent line and the second tangent line. A thread portion located one pitch rearward from the (2n) thread portion on the thread is defined as a (2n + 2) thread portion, and the (2n + 2) thread portion is threaded. When the thread portion located one pitch rearward along the line is the (2n + 4) th thread portion,
When n is 2, the (2n) thread portion is located one pitch rearward from the second thread portion along the thread,
n is any integer from 2 to 20,
The distance between the (2n) thread portion and the (2n + 2) thread portion is
An interval between the (2n + 2) th thread portion and the (2n + 4) th thread portion;
The screw structure according to any one of claims 1 to 3, which is substantially the same with respect to the screw axis direction.   n is an integer of 2 or more and 20 or less, and the height of the (2n) thread portion and the height of the (2n + 2) thread portion are approximately on the basis of the vertical direction of the screw axis. The screw structure according to claim 4, which is the same.   The bone screw provided with the screw structure for bones in any one of Claims 1-5.   The bone tap provided with the screw structure for bones in any one of Claims 1-5.

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