JP5638373B2 - A guide to assist with pedicle probe insertion - Google Patents

Description

  The present invention relates to a guide for assisting insertion of a pedicle probe when a screw insertion hole is formed in a pedicle of a vertebra in spinal fusion.

  In spinal diseases, spinal fusion is performed in which a screw is inserted into the pedicle and fixed in order to eliminate instability of the spinal column, correction of deformation, and instability that occurs after a nerve decompression procedure. According to spinal fusion, a pedicle probe is inserted into the left and right pedicles from the surface of the vertebra vertebrae to form a lead hole, and then the lead hole is threaded, whereby the pedicle screw insertion hole is formed. Then, the screw is screwed into the pedicle screw insertion hole.

By the way, the spine contains fragile tissues such as the spinal cord and the tail, and there are important tissues such as the aorta and vertebral artery around it. It is not uncommon for serious complications such as nerve damage to occur. In addition, erroneous insertion of the screw decreases the fixation with the bone, and directly leads to the remaining or worsening of symptoms due to a decrease in the bone fusion rate.
Therefore, accurate pedicle screw insertion is extremely important for successful spinal fusion.

  However, there are individual differences in the pedicle and pedicle shape, and accurate pedicle screw insertion depends largely on the experience of the operator. Even if an experienced operator performs an operation, about 10% of the screw It has been reported so far that deviation rates occur.

  Thus, in order to improve the accuracy of pedicle screw insertion in spinal fusion, it has been proposed to use intraoperative navigation techniques that have made significant progress in recent years. However, there are problems such as the fact that the device is very expensive, the procedure is complicated and takes time to set up, the accuracy may be lost due to inappropriate procedures, etc. Even when used, it has been reported that a screw misinsertion rate of about several percent occurs.

  Therefore, development of a simple means that enables accurate pedicle screw insertion is desired. As one of such means, a custom screw insertion guide designed and manufactured based on bone shape data formed from CT image data of a patient is known (for example, see Non-Patent Document 1).

  FIG. 4 is a perspective view showing an example of the custom screw insertion guide. The screw insertion guide is formed from "Duraform" polyamide using rapid prototyping technology based on patient CT image data. As shown in FIG. 4, the screw insertion guides are arranged in a standing state, spaced apart from each other and at a predetermined angle, and a pair of guide tubes 20 a and 20 b through which the pedicle probe can pass, And an arch portion 21 for connecting the guide cylinders. Further, first support legs 22a and 22b project from the lower ends of both sides of the arch part 21, respectively, and further, second support legs 23 project from the apex part of the arch part. Each of the first support legs 22a, 22b and the second support legs 23 has V-shaped edges 24a, 24b, 25 at the tips.

  In this guide, the first support legs 22a and 22b are respectively transverse processes in which the V-shaped edges 24a and 24b correspond to predetermined portions of the transverse process of the vertebra (see circles drawn by the white lines on the left and right in FIG. 5). And the second support leg 23 is placed at a predetermined portion of the spinous process (see the circle drawn by the white line in the center of FIG. 5), and the V-shaped edge 25 is placed across the spinous process. The apex portion of the arch portion 21 is pressed toward the vertebra and fixed to a predetermined portion of the vertebra. With the guides fixed in this manner, the pedicle probes are inserted into the pair of guide tubes 20a and 20b, respectively, and lead holes are formed in the left and right pedicles by the guides of the guide tubes 20a and 20b. .

However, according to this configuration, the guide is fixed by point contact with the vertebrae at the V-shaped edge of each of the three support legs. Therefore, the fixation of the guide is very unstable, and if the direction of the force pressing the guide against the vertebra is changed, the guide easily moves, and there is a possibility that the pedicle probe is erroneously inserted.
In addition, this guide is designed for a specific vertebra, but it is structured so that it can be easily adapted to other vertebrae. There was a risk of doing so.

  Furthermore, the bone shape data formed from the CT image data is greatly influenced by the resolution and image quality of the CT image, the bone region and the bone density, and cannot be said to accurately reflect the actual bone shape. . Therefore, when designing a guide based on bone shape data, it is important to set a guide fulcrum at a site where the reproducibility of the bone shape data is as high as possible. However, this conventional guide is designed in such a way that the contact point of the guide is located at a site where the reproducibility of the bone shape data is relatively low, such as the transverse process of the vertebra, so that the accuracy of the guide (accuracy of the pedicle probe) There was a problem that sufficient insertion was not guaranteed.

E. Berry, M. Cuppone, et al. "Personalised image-based templates for intra-operative guidance", Proc. Inst. Mech Eng., 2005, Vol.219, Part H., p. 111-118

  Accordingly, an object of the present invention is to provide a guide that can be accurately and stably fixed to a predetermined portion of a vertebra and can insert a pedicle probe with high accuracy.

In order to solve the above problems, the present invention supports the insertion of a pedicle probe from a vertebral surface of a preselected vertebra into the left and right pedicles when inserting a pedicle screw in spinal fusion. Therefore, the guide is placed on a predetermined portion of the vertebra and pressed and fixed, and the entire guide is formed based on the CT image data of the patient using a rapid prototyping technique, And a pair of guide cylinders which are arranged in a standing state and spaced apart at a predetermined angle so that the pedicle probe can penetrate with play and a rod, and one end of the guide A base is connected to the cylinder, the other end is connected to the other guide cylinder, a base that protrudes substantially in an inverted U shape or an inverted V shape from the plane on which the pair of guide cylinders are located, and a rod body The pair of guys A first connecting part that connects the cylinders to each other at a position above the connecting part with the base part, a vertex part of the base part is connected to the first connecting part, and a lower end opening of the pair of guide cylinders The right and left pedicle screw insertion holes are aligned with the positions where the left and right pedicle screw insertion holes are to be formed. The lower end opening edges of the pair of guide tubes are respectively fixed to the predetermined part of the vertebra by pressing and fixing to the predetermined part of the vertebra. When the guide is pressed and fixed to a predetermined portion of the vertebra at the apex portion of the base, there is no gap at the distal end of the spinous process. First support to contact The left and right portions of the base are respectively provided with second support surfaces that contact the vertebral arch without any gap when the guide is pressed and fixed to a predetermined part of the vertebra. The guide is characterized in that it is characterized.

According to a preferred embodiment of the present invention, the connecting portion between the apex portion of the base portion and the first connecting portion is provided with a pressing surface located on a surface crossing the axis of the pair of guide cylinders. In this case, it is more preferable that information indicating a correspondence relationship between the guide and the vertebra is displayed on the pressing surface.
According to another preferred embodiment of the present invention, the apex portion of the base portion is connected to the first connecting portion via a second connecting portion made of a rod. In this case, preferably, the connecting portion between the first connecting portion and the second connecting portion is provided with a pressing surface located on a surface crossing the axis of the pair of guide cylinders, and more preferably, Information indicating the correspondence between the guide and the vertebra is displayed on the pressing surface.

According to still another preferred embodiment of the present invention, the first support surface and the second support surface have a substantially circular, elliptical or polygonal profile.
According to still another preferred embodiment of the present invention, when the guide is pressed and fixed to a predetermined part of the vertebra on each of the left and right side portions of the base, the vertebrae of the vertebra are contacted without gaps. A third support surface is provided at a distance from the second support surface. In this case, it is preferable that the third support surface has a substantially circular, elliptical or polygonal outline.

  According to still another preferred embodiment of the present invention, the entire guide is made of titanium or a titanium alloy.

  According to the present invention, the guide is divided into the transverse process base of the vertebra (the position where the pedicle screw insertion hole is formed), the spine by the lower end opening edge of the pair of guide tubes, the first support surface, and the second support surface, respectively. Since it is fixed to a predetermined part of the vertebra by bringing it into surface contact with the tip of the projection and the vertebral arch, the guide will not move from its original position even if the direction of the force pressing the guide against the vertebra is slightly changed. Stablely fixed on the vertebra. As a result, erroneous insertion of the pedicle probe is prevented. In addition, since the surface is in contact with five surfaces, a guide designed for a specific vertebra does not fit at all to vertebrae other than the vertebra, thereby preventing misuse of the guide.

It is a figure which shows the guide which assists insertion of the pedicle probe by 1st Example of this invention, (A) is the three-dimensional figure seen from diagonally upward, (B) is the three-dimensional figure seen from the downward direction It is. FIG. 6 is a view similar to FIG. 1 showing a guide for assisting insertion of a pedicle probe according to a second embodiment of the present invention. FIG. 2 is a three-dimensional view showing a state in which the guide of FIG. 1 is applied to a predetermined vertebra of the human spine. It is a three-dimensional view showing an example of a conventional screw insertion guide. FIG. 5 is a plan view of a part of a spine of a human body showing a fixing position of the screw insertion guide of FIG. 4.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
(First embodiment)
FIG. 1 is a view showing a guide for supporting insertion of a pedicle probe according to a first embodiment of the present invention, (A) is a three-dimensional view seen from diagonally above, and (B) is from below. FIG.
As shown in FIG. 1, the guides according to the present invention are arranged upright and spaced apart and at a predetermined angle, each with a pedicle probe with play (0.1 mm to 2.0 mm). A pair of guide cylinders 1a and 1b that can penetrate through and a base 2 that connects the pair of guide cylinders 1a and 1b.

  The base portion 2 is formed of a rod body, and one end 2a is connected to one guide tube 1a, the other end 2b is connected to the other guide tube 1b, and a substantial plane from which the pair of guide tubes 1a and 1b are located. Projects in an upside-down U-shape or inverted V-shape.

  Furthermore, the guide of the present invention is composed of a rod body, the first coupling portion 3 that couples the pair of guide cylinders 1a and 1b to each other at a position above the connection portion with the base portion 2, and the rod body. The vertex part 2c and the 2nd connection part 4 which mutually connects the 1st connection part 3 are provided.

In the guide of the present invention, as shown in FIG. 3, the lower end openings of the pair of guide tubes 1a and 1b are aligned with the positions where the left and right pedicle screw insertion holes 10 are to be formed , and the apex portion of the base 2 2c crosses the distal end of the spinous process 12 of the vertebra, and the left and right portions of the base 2 extend along both sides of the spinous process 12, and are pressed and fixed to a predetermined portion of the vertebra. .

  Referring to FIGS. 1B and 3, the lower end opening edges 1 c and 1 d of the pair of guide tubes 1 a and 1 b contact the vertebra vertebra 11 with no gap when the guide is pressed and fixed to a predetermined portion of the vertebra, respectively. The apex portion 2c of the base portion 2 is provided with a first support surface 6 that contacts the distal end portion of the spinous process 12 without a gap when the guide is pressed and fixed to a predetermined portion of the vertebra. On the left side and the right side, second support surfaces 5a and 5b that contact the vertebral vertebra 11 with no gap when the guide is pressed and fixed to a predetermined portion of the vertebra are provided. In this case, the first support surface 6 and the second support surfaces 5a and 5b have a substantially circular outline (diameter is 2 to 6 mm). Note that the contour shapes of the first support surface 6 and the second support surfaces 5a and 5b may be substantially elliptical or polygonal.

  When the guide cannot be stably fixed on the vertebra only with the total of the five contact surfaces of the lower end opening edges 1c and 1d of the guide tubes 1a and 1b, the first support surface 6 and the second support surfaces 5a and 5b. Further, on the left side and the right side of the base portion 2, when the guide is pressed and fixed to a predetermined portion of the vertebra, the third support surfaces 7a and 7b that contact the vertebra vertebra 11 without gaps are provided as the second support. It is provided at an interval from the surfaces 5a and 5b. Similarly to the second support surfaces 5a and 5b, the third support surfaces 7a and 7b also have a substantially circular outline (diameter or major axis is 2 to 6 mm). In this case, the outline shape of the third support surfaces 7a and 7b may be substantially elliptical or polygonal.

Further, the connecting portion between the first connecting portion 3 and the second connecting portion 4 is provided with a pressing surface 8 that is located on a surface that crosses the axes of the pair of guide cylinders 1a and 1b. In this way, the finger of the operator or the assistant's hand is placed on the pressing surface 8, and the guide can be easily pressed and fixed to the corresponding vertebra without interfering with the insertion operation of the pedicle probe. .
It is preferable that information indicating a correspondence relationship between the guide and the vertebra is displayed on the pressing surface 8. In this embodiment, a number (or a combination of symbols and numbers) indicating the number of bones in each part such as the cervical vertebra, the thoracic vertebra, and the lumbar vertebra is stamped on the upper surface of the pressing portion 8. . Thereby, erroneous application of the guide is more reliably prevented.

Next, a guide design and manufacturing method according to the present invention will be briefly described.
First, a spinal CT image of a patient is taken, and bone shape data is extracted from the acquired CT image data by a computer using known image processing software. Based on the bone shape data, a guide according to the present invention is designed on a computer display.

  When designing the guide, the lateral process base on the vertebra surface (position where the pedicle screw insertion hole 10 should be formed), the tip of the spinous process 12 and the vertebra 11 have few anatomical irregularities, The contact surface of the guide is set at a site with high bone density and high reproducibility in the bone shape data. Thereby, even if only a low-resolution CT image can be obtained, the design of a guide that accurately fits the actual bone can be sufficiently guaranteed.

  Subsequently, the shape data of the designed guide and the bone shape data are confirmed on the CT image, and it is evaluated whether or not the guide is also adapted to a site where the bone shape data cannot be accurately reproduced on the CT image. Is done. And when the adaptability of the guide is insufficient, the guide is redesigned.

  When a guide having sufficient adaptability is designed, the guide is formed (produced) using a rapid prototyping technique based on the design data. In this case, any guide forming material can be used as long as it is safe to be applied to a living tissue, is stable to autoclaving or heat sterilization, and has an appropriate strength. However, in particular, titanium or a titanium alloy is preferable.

  In addition to the modeling of the guide, a bone model is produced using plaster, resin, or the like based on the same CT image data. The shaped guide is then applied to this bone model prior to its use in surgery, to assess whether the guide fits precisely against the actual bone and allows accurate insertion of the pedicle probe Is made. A design change is made to the guide determined to be incompatible in this evaluation. Specifically, the design change of the guide is executed by changing the position of the contact surface of the guide, adjusting the shape of the contact surface so as to conform to CT image data instead of bone shape data, or the like.

The usage of the guide of the present invention is as follows.
The guide of the present invention is used after sterilization. In the operation, after the bone surface is expanded, the guide is placed at a predetermined site of the corresponding vertebra, and the conformity and stability of the shape of the guide are evaluated. At this time, according to the present invention, the guide is formed by the lower end opening edges 1c and 1d of the pair of guide cylinders 1a and 1b, the first support surface 6, the second support surfaces 5a and 5b, and the third support surfaces 7a and 7b. Since the lateral process base of the vertebra (the position where the pedicle screw insertion hole 10 should be formed), the tip of the spinous process 12 and the vertebra 11 are fixed in contact with each other, the guide is fixed to a predetermined part of the vertebra. Even if the direction of the pressing force against the vertebra is slightly changed, the guide does not move from the initial position and is stably fixed on the vertebra. In addition, since the surface is brought into contact with seven surfaces, a guide designed for a specific vertebra does not fit at all to vertebrae other than the vertebra, thereby preventing misuse of the guide.

Then, when it is determined that sufficient compatibility and stability are obtained, screw insertion using a guide is performed. At that time, it is possible to use a known surgical support system such as intraoperative navigation and intraoperative radiography.
In this way, with the guide being pressed and fixed by the finger of the operator or its assistant's hand, an instrument for drilling the bone surface (Owl, steel wire with a sharp tip, etc.) is inserted into the guide tube, The screw insertion point is opened by the operator's procedure. The screw insertion point may be a fenestration of cortical bone having a diameter of about several millimeters by a high speed drill or the like.

Next, the pedicle probe is inserted into the guide tube, and a lead hole is formed by the operator's procedure. At this time, since there is a play of about 0.1 mm to 2.0 mm between the guide tube and the pedicle probe, the operator feels the bone inside the pedicle during the operation of the pedicle probe. Can be obtained. By creating a bone hole while obtaining a bone feel through the pedicle probe, the operator can instantly recognize that the pedicle probe has deviated outside the pedicle.
After confirming that the lead hole has been properly formed, the guide is removed from above the vertebra, the screw hole is tapped, and then the appropriate length of the pedicle screw is inserted.

(Second embodiment)
FIG. 2 is a view similar to FIG. 1 showing a guide for assisting insertion of a pedicle probe according to a second embodiment of the present invention. This embodiment is different from the embodiment of FIG. 1 only in the shape of the base and the way of connecting the base and the first connecting portion. Therefore, in FIG. 2, the same components as those shown in FIG.

  In the embodiment of FIG. 2, the base 2 ′ is greatly curved toward the first connecting portion 3 side, and the apex portion 2 c ′ is directly connected to the first connecting portion 3, so that the embodiment of FIG. The second connecting portion 4 is omitted. A pressing surface 8 is provided at a connection portion between the apex portion 2 c ′ of the base portion 2 ′ and the first connecting portion 3.

As described above, by changing the shape of the base and the way of connecting the base and the first connecting portion, a guide having a structure more suitable for the shape of each vertebra can be realized.
It goes without saying that this embodiment also has the same effect as the embodiment of FIG.

1a, 1b Guide tube 1c, 1d Lower end opening edge 2, 2 'Base 2a, 2a' One end 2b, 2b 'Other end 2c, 2c' Vertex portion 3 First connecting portion 4 Second connecting portions 5a, 5b Second support surface 6 1st support surface 7a, 7b 3rd support surface 8 Pressing surface 9 Information 10 Pedicle screw insertion hole 11 Larch 12 Spinous process

Claims (10)

When inserting a pedicle screw in spinal fusion, the pedicle probe is placed at a predetermined position of the vertebra to assist the insertion of the pedicle probe into the left and right pedicles from the vertebral surface of the preselected vertebra. A guide that is pressed and fixed,
The entire guide is formed based on patient CT image data using rapid prototyping technology,
A pair of guide tubes that are spaced from each other in a standing state and at a predetermined angle, through which the pedicle probe can penetrate with play;
It is composed of a rod, and one end is connected to one of the guide cylinders, the other end is connected to the other guide cylinder, and the plane in which the pair of guide cylinders are located is substantially inverted U-shaped or inverted V-shaped. A base protruding in a shape,
A first connecting portion that is composed of a rod body and connects the pair of guide cylinders to each other at a position above the connecting portion with the base portion;
An apex portion of the base is connected to the first connecting portion;
The lower end openings of the pair of guide tubes are aligned with positions where left and right pedicle screw insertion holes are to be formed, respectively, and the apex portion of the base crosses the distal end of the spinous process of the vertebra, and the left side of the base And the right side portion is arranged to extend along both sides of the spinous process, and is pressed and fixed to a predetermined part of the vertebra,
The lower end opening edges of the pair of guide tubes each have a shape that makes contact with the vertebral arch of the vertebra without any gap when the guide is pressed and fixed to a predetermined portion of the vertebra. When the guide is pressed and fixed to a predetermined part of the vertebra, a first support surface is provided to contact the distal end portion of the spinous process without a gap, and the left and right portions of the base are respectively provided with the guide. The guide is provided with a second support surface that comes into contact with the vertebral arch of the vertebra without any gap when pressed onto a predetermined portion of the vertebra.   The pressing surface located on the surface which crosses the axis | shaft of a pair of said guide cylinder is provided in the connection part of the vertex part of the said base, and a said 1st connection part, The Claim 1 characterized by the above-mentioned. guide.   The guide according to claim 2, wherein information indicating a correspondence relationship between the guide and the vertebra is displayed on the pressing surface.   2. The guide according to claim 1, wherein an apex portion of the base portion is connected to the first connection portion via a second connection portion made of a rod.   The connecting portion between the first connecting portion and the second connecting portion is provided with a pressing surface located on a surface crossing the axis of the pair of guide cylinders. guide.   The guide according to claim 5, wherein information indicating a correspondence relationship between the guide and the vertebra is displayed on the pressing surface.   The guide according to any one of claims 1 to 6, wherein the first support surface and the second support surface have a substantially circular, elliptical, or polygonal outline.   When the guide is pressed and fixed to a predetermined portion of the vertebra on each of the left and right side portions of the base, a third support surface that contacts the vertebral arch without any gap is spaced from the second support surface. The guide according to claim 1, wherein the guide is provided with a gap.   The guide according to claim 8, wherein the third support surface has a substantially circular, elliptical, or polygonal outline.   The guide according to any one of claims 1 to 9, wherein the entire guide is made of titanium or a titanium alloy.