JP2000051223A - Shaft fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely fix shaft by forming a female screw part with a diameter and pitch equal to the female screw part of a rising part inside of a cylindrical cap positioned between rising parts and fastening the shaft at the tip part of a male body to screw in common with both of the female screw parts to eliminate possibility of falling-off of the cap. SOLUTION: The shaft fixing device 10 is provided with a groove for putting through the shaft 11 and respective rising parts 13 and 14 rising on both sides of this. In addition, the female screw part 16 to which the male screw body 15 fixing the shaft 11 is screwed is provided at the respective parts 13 and 14 and a cylindrical cap 17 preventing the expand-opening of the respective parts 13 and 14 is externally fitted. In addition, a part with the groove 12 is a part of a pedicle 20 with a screw 21, e.g. Then, the female screw part 18 with the same diameter and pitch as the part 16 of the respective parts 13 and 14 is formed on the inner surface of the cap 17 positioned between the respective parts 13 and 14 and both of the parts 16 and 18 and the male body 15 are screwed to fasten the shaft 11 at the tip part of the male screw body 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for osteosynthesis and the like, and has a rising portion on both sides of a groove through which a shaft passes, and a male screw for fixing the shaft disposed in the groove is screwed. The present invention relates to a shaft fixing device having a configuration in which a female screw portion is provided in the rising portion and a cylindrical cap for preventing the rising portion from spreading is fitted to the outside.

[0002]

2. Description of the Prior Art Devices of this type are used, for example, in connection with spinal column implants, to connect a screw that is screwed into a vertebra with a rod that is arranged along the spinal column. . However, in conventional devices, the cap only contacts the outside of the riser.

[0003] Since the rising portion is pushed and spread by the male screw body by meshing with the internal female thread portion, the pressing force also increases the frictional force with the cap. However, it is only the frictional force that holds the cap off, which can cause the cap to come off.

[0004] When the cap comes off, there is a high possibility that the male screw body is loosened. Therefore, there is no need to fix the rod.
In the worst case, it may be off.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above point, and an object of the present invention is to eliminate the possibility that the cap will come off and secure the shaft.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention has the same thread diameter and pitch as those of the female thread of the rising portion inside the cylindrical cap located between the rising portions. A means is provided in which a female thread is formed, and the shaft is fastened at the tip of a male thread which is screwed together with both female threads.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A shaft fixing device 10 according to the present invention.
The shaft 1 has a groove 12 through which the shaft 11 passes and rising portions 13 and 14 rising on both sides thereof.
Female screw part 16 into which a male screw body 15 for fixing
Is provided in the rising portions 13 and 14, and the rising portion 1
Cylindrical cap 17 for preventing the spread of 3, 14
Is fitted to the outside.

The portion having the groove 12 is shown in FIG. 1 as part of a pedicle 20 having a screw 21. However, this is an example, and the connecting shaft 22 shown in FIG.
May be provided at one end of a member 23 having a hook, or may be provided on a hook-type member 25 having a hook 24 hooked on a part of a vertebra as shown in FIG. Each of the above members 23 and 25 is an example of a member used as a part of an implant.

In this device, the present invention is characterized in that the female screw portion 1 of the rising portions 13, 14 is provided on the inner surface of a cylindrical cap 17 located between the pair of rising portions 13, 14.
Forming a female thread portion 18 having the same thread diameter and pitch as that of 6, and tightening the shaft body 11 at the distal end portion of the male thread body 15 by screwing the both female thread portions 16, 18 and the male thread body 15. It is characterized by.

The fact that the two female threads 16 and 18 have the same thread diameter and pitch means that two female threads act on one threaded body 15 at the same time. This action is similar to that of a doubled nut and has the effect of preventing loosening.

The embodiment shown in the drawings will be described more specifically. In the illustrated example, a step 26 is provided on the outer periphery of the rising portions 13 and 14, and the tip 27 of the cap 17 hits the step 26 for positioning. That is, when the step 26 and the tip 27 are in contact with each other, both the female threads 16 and 18 become one female thread and are screwed with the male screw body 15. Of course, step 2
Although the screwing is possible even if the tip 6 and the tip 27 are separated by one pitch or more, the internal thread portions 16, 18 are always continuous as a helical screw in the above-mentioned contact state.

The cap 17 has a recess 19 through which a part of the shaft 11 passes. Since the concave portion 19 forms a part of the cross-sectional shape of the shaft body 11 together with the groove portion 12, the cap 17
When the tip 27 of the shaft abuts on the step 26 on the outer periphery of the rising portion, the tip 27 becomes substantially the same as the cross-sectional shape of the shaft body 11.

The cap 17 has rising portions 13 and 14
Receiving portions 28, 29 on the inside and portions 31, 32 projecting inward relative thereto, between the receiving portions 28, 29 and projecting portions 3
The inner surfaces of the first and second 32 are female screw portions 18. See FIG. 4 and FIG. In each figure, reference numeral 33 denotes a wrench hole,
Used to insert a wrench when tightening or loosening.

The apparatus 10 of the present invention having such a configuration
Can be used for the purpose of connecting the pedicle 20 and the like to the shaft 11 for fixing a spine or a lumbar spine, for example. See FIG. In the device 10 of the present invention, the cap 17 is not only prevented from being detached by screwing with the male screw body 15 but also can be placed in a state where the cap 17 is prevented from loosening. The female thread 18 on the cap 17 side is
By providing the threaded portion 15 to the inlet portion 18 ′ which does not overlap with the female thread portion 16, the male screw body 15 can be integrated with the cap portion 17 in advance, and the handling property such as prevention of loss of the male screw body 15 is improved. It also contributes.

[0015]

Since the present invention is constructed and operates as described above, the cap may be disengaged by screwing a screw body into the threaded portion to be provided both inside the rising portion and inside the cap. And the effect that the shaft can be more securely fixed can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing Embodiment 1 of a shaft fixing device according to the present invention.

FIG. 2 is a perspective view showing the second embodiment.

FIG. 3 is a perspective view showing a third embodiment.

FIG. 4 is a longitudinal sectional view showing a main part of the device of the present invention.

FIG. 5 is a transverse sectional view of the same.

FIG. 6 is a perspective view showing a use state of the device of the present invention.

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[Procedure amendment]

[Submission date] July 19, 1999 (1999.7.1)
9)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0002

[Correction method] Change

[Correction contents]

[0002]

2. Description of the Related Art Shaft fixing devices of this type are used, for example, in connection with spinal column implants, to connect a screw screwed into a vertebra with a rod (shaft) arranged along the spinal column. Have been. However, with conventional equipment,
The cap only contacts the outside of the riser.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

The cap 17 has a recess 19 through which a part of the shaft 11 passes. The recess 19 together with the groove 12 forms a part of the cross-sectional shape of the space through which the shaft 11 passes . When the tip 27 of the cap 17 comes into contact with the step 26 on the outer periphery of the rising portion, it becomes minimum, that is, substantially the same as the cross-sectional shape of the shaft body 11.

[Procedure amendment 4]

[Document name to be amended] Drawing

[Correction target item name] Fig. 5

[Correction method] Change

[Correction contents]

FIG. 5

Claims (3)

[Claims] An upright portion is provided on both sides of a groove through which a shaft body passes, and a female screw portion into which a male screw body for fixing the shaft body disposed in the groove is screwed, wherein the upright portion is expanded. A shaft fixing device having a configuration in which a cylindrical cap for preventing the shaft is fitted to the outside, wherein the same screw diameter as the female screw portion of the rising portion is provided inside the cylindrical cap located between the rising portions. And a female screw part having a pitch, and a shaft body is fastened at a distal end portion by screwing both female screw parts and a male screw body. 2. The cap according to claim 1, wherein the cap has a portion for receiving a rising portion on the inner side, and a portion protruding inward relative to the receiving portion between the receiving portion and the inner surface of the protruding portion. The shaft body fixing device according to claim 1, which is a part. 3. The shaft fixing device according to claim 2, wherein a stepped portion is provided on the outer periphery of the rising portion, and the tip of the cap hits the stepped portion to perform positioning.