KR20220107762A - Spinal Fixation Device having excellent elasticity deformation and fixing power property - Google Patents

Abstract

The present invention relates to a spinal fixation device that is coupled to adjacent vertebrae and is used to physically fix or correct a vertebra. While an elastic connector fastened to a bone screw inside an insertion housing is easily coupled without deformation or tearing, the bone screw is more firmly fastened within the insertion housing. Thus, the spinal fixation device can be stably fixed to a spine without being pulled out by external force.

Description

Spinal Fixation Device having excellent elasticity deformation and fixing power property

The present invention relates to a spinal fixation device used for physically fixing or correcting a vertebra by coupling to an adjacent vertebra, and more particularly, an elastically deformable and coupled vertebral bone screw to be easily coupled to the vertebrae. It relates to a spinal fixation device having an excellent fixing force so that the vertebral bone screw is not pulled out by an external force.

The spine is connected and supported by discs between each bone to maintain the posture. When an abnormal posture is maintained for a long time, degenerative diseases due to aging, or an external shock is received, the disc is damaged and spinal disc disease occurs.

In spinal disc disease, nerves connected to each part of the body through vertebral bone nodes are compressed, causing pain, and thus, in patients with vertebral disc disease, surgery is performed to prevent the damaged part of the vertebral bone from being pressed or compressed.

In spinal disc surgery, the disc is first removed from the damaged area, and bone fragments are filled in a hollow metal or plastic artificial prosthesis and inserted into the area where the disc was removed. Then, by inserting and fixing a plurality of bone screws into the vertebrae of the upper and lower parts of the damaged disc and connecting a support rod disposed in the longitudinal direction of the vertebrae thereto to secure a distance between the vertebrae, bone fusion is performed normally.

Such a device used for spinal surgery is disclosed in Korean Patent Application Laid-Open Nos. 10-2011-0073283 and 10-2013-0137202, which rotatably accommodates a bone screw implanted in the spine and a head of the bone screw at a predetermined angle. a housing, a connector that is coupled to the housing and the head of the bone screw is inserted in the lower part, a support rod that is coupled to the upper part of the connector to connect a plurality of bone screws, and a set screw that is fastened to the upper part of the housing and fixes the support rod to the housing consist of.

Here, the bone screw is inserted and coupled to the lower end of the connector by a support rod pressed from above to engage with the connector. .

In order to improve this, Korean Patent Registration No. 10-1868694 has proposed a vertebral bone fixation device having a connector elastically variable by an external force. It is formed in a zigzag along the ridge and is easily deformed without applying a large external force in the upper direction, so that the head of the bone screw can be inserted in the lower part.

However, as such a connector is formed to have a thin thickness for elastic deformation, stress is concentrated in the incision groove formed in the horizontal direction when an external force in the vertical direction is applied for coupling with the connector. There is a risk of excessive deformation or tearing due to concentration.

When the bone fixing screw is inserted into the connector in such a state of being excessively deformed or torn, it cannot be firmly fixed even with the normal movement of the patient after a certain period of time after surgery, and there is a problem in that it is moved from the fixed position or, in severe cases, is detached from the connector. .

In addition, since the above-described spinal fixation device is arranged in a zigzag horizontally as well as horizontally to facilitate elastic deformation, there is a problem in that the binding force with the bone fixation screw is particularly weak.

Republic of Korea Patent Publication No. 10-2011-0073283 (Title of the invention: bone fixation device) Korean Patent Laid-Open Publication No. 10-2013-0137202 (Title of the Invention: Multiaxial Bone Anchor with Open Planar Retainer, Pop-on Shank and Frictional Engagement Insert) Republic of Korea Patent Publication No. 10-1868694 (Title of the invention: bone fixing screw device and its fastening method)

Therefore, the present invention was devised to solve the problems of the conventional spinal fixation device described above, and while elastically deformable to easily couple the vertebral bone screw fixed to the spine, the coupled vertebral bone screw is pulled out by an external force. It is an object of the present invention to provide a spinal fixation device having excellent fixing power so as not to be out).

In order to solve the above problems, the present invention provides a spinal fixation device in which a screw head of a bone screw, one end of which is inserted and fixed into the spine, is connected to a support rod by an elastic connector coupled to the insertion housing and is rotatably accommodated in the insertion housing. , The elastic connector is a spinal fixation device in which a circular open groove having a predetermined radius from the center aligned with the center line of the straight open groove is formed at the end of the straight open groove formed in the vertical direction from the lower end of the cylindrical body having a hollow formed therein. provided

Here, a plurality of circular open grooves formed in the elastic connector of the present invention are formed at equal intervals along the circumference of the cylindrical body, and the centers of the plurality of circular open grooves are aligned on the circumference of the body.

And, the cylindrical body of the present invention is formed with a head binding portion that gradually decreases the diameter of the hollow toward the lower end.

In this case, the diameter of the circular open groove formed in the elastic connector of the present invention is 4 to 6 times the width of the straight open groove, and the length of the straight open groove is 0.7 to 1.5 times the diameter of the circular open groove.

In addition, the maximum load for pulling out the bone screw in which the screw head is coupled to the elastic connector of the present invention is very excellent at 6,200 to 7,000N.

According to the present invention, while the elastic connector fastened with the bone screw inside the insertion housing is easily coupled without deformation or tearing, as the bone screw is more firmly coupled within the insertion housing, the spine is stably secured without being pulled out by an external force. can be fixed to

1 is a perspective view of a spinal fixation device according to the present invention.
2 is an exploded perspective view of the spinal fixation device according to the present invention.
3 is a cross-sectional view of the spinal fixation device according to the present invention.
4 is an enlarged perspective view of the elastically variable connector according to the present invention.
5 is a view showing a state in which the lower end of the elastic connector is expanded so as to be coupled to the screw head.
6 is a view showing a state in which the lower end of the elastic connector constrains the outer surface of the screw head by being pressed downward.
7 is a photograph of the elastic connector according to the first embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

This embodiment is provided to more completely explain the present invention to those with average knowledge in the art. may be exaggerated or reduced for

In addition, in describing the embodiment, if a component is described as "comprising", "coupled", "fixed", etc. to another component, it is directly provided, coupled and fixed to the other component. There may be, but it should be understood that other components may exist in the middle.

In addition, when it is determined that the technical features of the present invention may be unnecessarily obscured as it is already obvious to a person skilled in the art, such as a known function or a known configuration related in principle in explaining the embodiment, the detailed description thereof A description will be omitted.

1 is a perspective view of a spinal fixation device 100 according to the present invention, and FIGS. 2 and 3 are exploded perspective and cross-sectional views thereof, respectively. 1 to 3 , the spinal fixation device 100 according to the present invention includes a bone screw 110 , an insertion housing 120 , an elastic connector 130 , a support rod 140 , and a set screw 150 . be prepared

The bone screw 110 consists of a spherical screw head 111 and a screw body 112 extending therefrom. A wrench groove is formed in the upper portion of the spherical screw head 111 for rotation of the bone screw 110, and is rotated by a wrench fastened thereto so that the screw body 112 is inserted and fastened to the spine. The screw body 112 has a screw thread 113 continuously protruding along the spiral direction is formed at a predetermined pitch and is firmly coupled to the inserted spine.

The insertion housing 120 is a cylindrical housing in which a head insertion groove 121 penetrating in the vertical direction is formed so that the screw head 111 is rotatably inserted at a predetermined angle, and is supported on opposite sides of the insertion housing 120 . A support rod accommodating groove 122 in the form of a "U" with an open upper side is formed in communication with the head insertion groove 121 so that the rod 140 is fastened. In addition, the head insertion groove 121 of the insertion housing 120 has a side surface formed with an inclined surface 123 so that the diameter becomes smaller toward the bottom thereof, and the elastic connector 130 inserted therein is elastically deformed inward to form the screw head 111 . ) is bound to

Such an elastic connector 130 is made of a body in which a hollow 131 is formed, and a screw head 111 of a bone screw is rotatably coupled to the hollow 131 in the head insertion groove 121, and is inserted into the upper portion. A pair of support rod coupling grooves 132 aligned with the support rod receiving groove 122 of the housing 120 are formed, and the support rod 140 and the support rod 140 by the set screw 150 screwed to the insertion housing 120 are combined

At this time, the elastic connector 130 is formed in a cylindrical body having a thin thickness of several mm, and as shown in FIG. 4 , a straight open groove 133 and a straight open groove formed in the vertical direction from the bottom of the body ( A circular open groove 134 is formed at the end of the 133 , and is elastically coupled to the screw head 111 inside the head insertion groove 121 . Here, the straight open groove 133 is formed to have one end open at the lower end of the elastic connector 130 , and the circular open groove 134 is formed from the center O aligned with the center line C of the straight open groove 133 . It is formed to have a predetermined radius (r). These straight open grooves 133 and circular open grooves 134 are formed in plurality along the circumference of the cylindrical body.

The coupling method of the spinal fixation device 100 using such an elastic connector 130 will be described below. First, after inserting the screw head 111 of the bone screw into the head insertion groove 121 from the lower side of the insertion housing 120, pressing the lower end of the elastic connector 130 on the upper part of the inserted screw head 111, As shown in Figure 4, the circular open groove 134 is elastically deformed in the longitudinal direction as well as in the transverse direction along the radius r while the circular opening 134 is changed into an oval shape, and accordingly, the circular opening 134 is deformed in the lateral direction. The width W of the end of the straight open groove 133 connected to the is expanded so that the screw head 111 of the bone screw is easily inserted into the hollow 131 of the connector.

And when the elastic connector 130 and the screw head 111 are coupled, the support rod 140 is seated in the pair of coupling grooves 132 above the insertion housing 120 , and the set screw 150 is inserted into the insertion housing. After fastening the screws with 120 , the support rod 140 , the elastic connector 130 , the insertion housing 120 and the bone screw 110 are firmly coupled to each other by moving downward. At this time, when the support rod 140 presses the elastic connector 130 by the downward movement of the set screw 150 , the elastic connector 130 into which the screw head 111 is inserted into the hollow 130 is inserted into the head insertion groove ( 121) is moved downward along the inner inclined surface 123 to form, whereby the lower end of the elastic connector 130 is elastically deformed inward, and is more firmly coupled to the outer surface of the screw head 111.

5 shows the state before and after the deformation of the elastic connector 130, as described above, when an external force is applied in the vertical direction of the elastic connector 130, the radius (r) of the circular opening groove 134 As it is dispersed in the longitudinal and transverse directions along the , stress is not concentrated at a specific point of the elastic connector 130 having a thin thickness, unlike the prior art, so that it can be elastically deformed without being deformed or torn.

At this time, the elastic connector 130 has straight open grooves 133 and circular open grooves 134 formed at equal intervals around the body to evenly distribute the external force in the vertical direction, and the elastic connector ( 130), the diameter (φ) of the circular open groove 134 is formed to be 4 to 6 times the width (W) of the straight open groove so that the strength can be maintained.

If the diameter (φ) of the circular open groove is less than 4 times the width of the straight open groove (W), the external force cannot be sufficiently dispersed. The thickness of the elastic connector 130 may be deformed or damaged.

After the screw head 111 is received and coupled to the elastic connector 130 elastically deformed, the length L of the straight open groove is the diameter of the circular open groove so that it is not pulled out by an external force acting backward. It is formed with 0.7~1.5 times of φ). Here, if the length (L) of the straight open groove is less than 0.7 times the diameter of the circular open groove (φ), the circular open groove 134 is close to the open end of the straight open groove 133, and the screw of the received bone screw. The head 111 can be easily separated to the lower end by an external force, and when the length (L) of the straight open groove exceeds 2.5 times the diameter of the circular open groove (φ), the deformation force of the circular open groove 134 is linearly opened. It is difficult to be transmitted to the end of the groove 133, and the lower end is difficult to elastically deform.

The circular open groove 134 formed in this way is formed with the center (O) aligned on the circumference of the body to have the same height. In addition, the elastic connector 130 is preferably formed with a head binding portion 134 in which the diameter of the hollow 131 gradually decreases toward the lower end as shown in FIG. 4 , which is inserted by the head binding portion 135 . The screw head 111 of the bone screw can be more firmly coupled.

In the present invention made in this way, while the elastic connector 130 fastened with the bone screw 110 inside the insertion housing 120 is easily coupled without deformation or tearing, the bone screw 110 is inserted in the insertion housing 120 . As it is more firmly bound, it can be stably fixed to the spine without being pulled out by an external force.

Examples of the present invention will be described below by comparing them with comparative examples.

<Example 1>

A bone screw, an insertion housing, an elastic connector, a support rod, and a set screw having the dimensions shown in Table 1 below were manufactured from titanium material with excellent physiological compatibility.

At this time, as shown in FIG. 6 , the elastic connector forms eight straight open grooves that open downward with a width of 0.35 mm and a length of 2 mm at equal intervals, and forms a circular open groove with a diameter of 2 mm at the end of the straight open groove to form a bone screw. , interlocked with the insert housing, support rod and set screw.

<Example 2>

An elastic connector having a circular open groove having a diameter of 2.4 mm was manufactured, and combined with the bone screw, insertion housing, support rod, and set screw of Example 1.

<Example 3>

An elastic connector having a straight open groove having a width of 0.35 mm and a length of 1.4 mm was manufactured, and combined with the bone screw, insertion housing, support rod and set screw of Example 1.

<Comparative example 1>

An elastic connector having a circular open groove having a diameter of 3 mm was manufactured, and combined with the bone screw, insertion housing, support rod and set screw of Example 1.

<Comparative example 2>

An elastic connector having a straight open groove having a width of 0.35 mm and a length of 1 mm was manufactured, and combined with the bone screw, insertion housing, support rod and set screw of Example 1.

<Comparative example 3>

An elastic connector having alternately formed first T-shaped grooves and second-shaped grooves on the outer surface at equal intervals was manufactured, and combined with the bone screw, insertion housing, support rod and set screw of Example 1 (a prior art registered patent) Publication No. 10-1868694).

Here, the first vertical groove of the first T-shaped groove is opened to the bottom with a width of 0.35 mm and a length of 4 mm, and the first horizontal groove horizontally crossing the end thereof is formed with a width of 0.35 mm and a length of 3.4 mm, and the second The second vertical groove of the T-shaped groove has a width of 0.35 mm and a length of 2 mm, which is also opened to the bottom, and a second horizontal groove that horizontally crosses the end thereof is also formed with a width of 0.35 mm and a length of 3.4 mm.

Examples 1 to 3 and Comparative Examples 1 to 3 prepared in this way were pulled out (Pull- out) was measured, and the results are shown in Table 2 below.

Looking at Table 2 above, Example 1 had a very good maximum load of 7,047N, and the maximum load of Example 2, which had a larger diameter (φ) of the circular open groove than Example 1, was 6,547N, which was lower than that of Example 1. It was good, and the maximum load of Example 3, in which the length (L) of the straight open groove was shorter than in Example 1, was 6,213N, which was lower than that of Examples 1 and 2, but it was confirmed that it was good at 6,000N or more.

In comparison, it was confirmed that the maximum load of Comparative Examples 1 and 2 was 5,215N and 5,078N, respectively, which was lower than that of the Example, which was compared to the width (W) of the straight open groove in Comparative Example 1 with the diameter ( φ) is formed too large, and in Comparative Example 2, it is determined that the length (L) of the straight open groove is formed too short.

And, in the case of Comparative Example 3, the maximum load was 4,832N, which was measured lower than that of Comparative Examples 1 and 2 as well as Examples, which is due to the T-shaped groove formed in a zigzag shape along the periphery of the connector in the horizontal direction. is judged

The present invention described above is not limited to the described embodiments, and it is apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the present invention. Accordingly, it should be said that such variations or modifications fall within the scope of the claims of the present invention.

100: spinal fixation device 110: bone screw
111: screw head 112: screw body
113: thread 120: insert housing
121: head insertion groove 122: support rod receiving groove
123: inclined surface 130, 200: elastic connector
131: hollow 132: support rod coupling groove
133: straight open groove 134: circular open groove
135: head binding unit 140: support rod
150: set screw
C : Straight open groove center line L : Straight open groove length
W : Width of straight open groove O : Center of circular open groove
φ : diameter of circular open groove
210: first T-shaped groove 211: first vertical groove
212: first horizontal groove 220: second T-shaped groove
221: second vertical groove 222: second horizontal groove

Claims (7)

In the spinal fixation device, the screw head of a bone screw whose one end is inserted and fixed into the spine is connected to the support rod by an elastic connector coupled to the insertion housing and is rotatably inserted in the insertion housing,
The elastic connector,
Spinal fixation device, characterized in that at the end of the straight open groove formed in the vertical direction from the lower end of the cylindrical body having a hollow formed therein, a circular open groove having a predetermined radius from the center aligned with the center line of the straight open groove is formed. . According to claim 1,
The circular open groove,
Spinal fixation device, characterized in that formed in a plurality at equal intervals along the circumference of the cylindrical body. 3. The method of claim 2,
A spinal fixation device, characterized in that the centers of the plurality of circular openings are aligned on the circumference of the body. 4. The method of claim 3,
The cylindrical body is
Spinal fixation device, characterized in that the head binding portion is formed that the diameter of the hollow gradually decreases toward the lower end. 5. The method of claim 4,
The diameter of the circular open groove is,
Spinal fixation device, characterized in that it is formed 5 to 8 times the width of the straight open groove. 6. The method of claim 5,
The length of the straight open groove is,
Spinal fixation device, characterized in that 0.7 to 1.5 times the diameter of the circular open groove. 7. The method of claim 6,
Spinal fixation device, characterized in that the maximum load for the screw head to pull out the bone screw coupled to the elastic connector is 6,200 ~ 7,000N.

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