JP2022006246A - Method for designing intervertebral spacer and program - Google Patents

Abstract

To design a semi-custom-made intervertebral spacer that is always adapted to a patient, regardless of posture of a patient adopted in the X-ray projection mage photographing.SOLUTION: Vertebral body displacement information is acquired on the basis of the X-ray projection image of the spine. Also, vector image data of first and fourth free-form curves adapted to each of a plurality of surfaces parallel to a coronal plane and a line intersection with a head side end plate of the caudal side vertebral body between the target vertebral bodies and a caudal side end plate of the head side vertebral body is acquired along with that of a third free-form curve for determining a cross-sectional contour of the intervertebral spacer. A free curve is repositioned in a three-dimensional coordinate system, first and second surfaces are formed from the first and fourth free-form curves, respectively, and the positional relationship of the first and second surfaces is corrected on the basis of the vertebral body displacement information. The first and second surfaces are made as the caudal side and head side end plate surfaces of the intervertebral spacer, and thereby the side of the intervertebral spacer is formed from the locus at the time when the third free-form curve is moved between the caudal side and head side end plates.SELECTED DRAWING: Figure 1

Description

The present invention relates to methods and programs for designing intervertebral spacers used in spinal fusion.

Injuries to the spine include injuries caused by diseases such as trauma, degeneration, and tumors, and injuries caused by surgical techniques for treating them (damage caused by unavoidable excision of ligaments, joints, etc. during surgery). However, spinal fusion is one of the therapeutic means for such spinal injuries.

Spinal fusion is a surgical technique that connects and fixes two or more destabilized vertebrae, and in spinal fusion, intervertebral spacers are used. Intervertebral spacers are inserted between unstable vertebral bodies and fuse with those vertebral bodies to secure them to each other.

Conventionally, in Japan, ready-made products imported from overseas have been generally used as intervertebral spacers.
However, many of these intervertebral spacers are of a size and shape that do not fit the spine of the Japanese, who have a physical disparity with foreigners. It was necessary to match it with the intervertebral spacer, and it had the disadvantage of being highly invasive to the patient.

Therefore, a method has been proposed in which the intervertebral spacer is fully custom-made and a dedicated intervertebral spacer is designed for each patient (see, for example, Non-Patent Document 1).
According to this conventional method, first, an image analysis is performed using a three-dimensional image analysis software based on a three-dimensional X-ray projection image of the patient's spine, and a binarized three-dimensional X-ray projection image is used as a target. A three-dimensional image of each of the pair of vertebral bodies (cranial vertebral body and caudal vertebral body) related between the vertebral bodies is extracted, and STL data of the extracted three-dimensional image is acquired.

Next, based on the acquired STL data, using three-dimensional modeling software, the shape of the cross section of the intervertebral spacer based on the shape of the cranial endplate surface in the caudal vertebral body of the pair of vertebral bodies. Then, with this cross-sectional shape as the bottom surface, a columnar body having a height corresponding to the distance between the target vertebral bodies is formed. In addition, the bottom surface of this columnar body is replaced by the caudal endplate surface of the caudal vertebral body, the upper surface of this columnar body is replaced by the caudal endplate surface of the caudal vertebral body, and an intervertebral spacer is formed. , The design data of the intervertebral spacer is acquired.

Then, based on the design data of this intervertebral spacer and the original 3D X-ray projection image of the patient's spine, 3D image analysis software is used to check the suitability of the intervertebral spacer, if necessary. The design data is modified.

According to this design method, it is possible to design (manufacture) an intervertebral spacer of the optimum shape and size for each patient, so it is necessary to fit the patient's body to the intervertebral spacer by scraping the patient's bones, etc. It is possible to perform a minimally invasive treatment for the patient.

However, on the other hand, it takes a considerable amount of time and effort to extract an image of a pair of vertebral bodies related to the target vertebral bodies from a three-dimensional X-ray projection image of the patient's spine, and therefore, the intervertebral body. There is a problem that the manufacturing cost of the spacer is high, the treatment using the intervertebral spacer becomes expensive, and the patient is forced to bear a large cost.

In addition, in some patients with spinal damage, the head and caudal vertebral bodies between the target vertebral bodies are displaced from their normal positions due to the deformation of the intervertebral disc. A three-dimensional X-ray projection image is obtained in which the cranial and caudal vertebral bodies between the target vertebral bodies are displaced from their normal positions.

However, the design method described above does not take into account the correction of this deviation, so that even with the designed intervertebral spacers, the cranial and caudal vertebral bodies between the target vertebral bodies are In some cases, they were not corrected to the normal positional relationship with each other.

2013 Problem-solving medical device development project "Development of tailor-made devices using SLM technology in the treatment of osteoarthritis" R & D result report (summary version), consignor Ministry of Economy, Trade and Industry, consignee Sagawa Printing Co., Ltd. , February 2014, p. 18-19

Therefore, an object of the present invention is to provide a means capable of designing a semi-custom-made intervertebral spacer that is always suitable for a patient regardless of the posture of the patient at the time of taking an X-ray projection image.

In order to solve the above problems, according to the first invention, there is a method of designing an intervertebral spacer, in which (1) a three-dimensional orthogonal coordinate system is provided in a three-dimensional X-ray projection image of a patient's spine. The axis extends parallel to the midline, the XX plane extends parallel to one of the coronal and sagittal planes, and the YZ plane extends parallel to the other of the coronal and sagittal planes. And (2) the step of acquiring the vertebral body displacement information regarding the relative displacement of the cranial and caudal vertebral bodies between the target vertebral bodies in the three-dimensional X-ray projection image, and (3) the above. A plurality of first free curves fitted to the intersection of each of the planes parallel to the XX plane of the three-dimensional orthogonal coordinate system with the cranial end plate of the caudal vertebral body, and / or the cubic. Vector image data of a plurality of second free curves conforming to the intersection of each of the plurality of planes parallel to the YY plane of the original orthogonal coordinate system and the cranial end plate of the caudal vertebral body, and the above. Vector image data of a third free curve that determines the contour of the caudal end plate of the intervertebral spacer to be designed on a plane parallel to the XY plane of the three-dimensional orthogonal coordinate system, and the three-dimensional orthogonal coordinate system. A plurality of fourth free curves fitted to the intersection of each of the plurality of planes parallel to the XZ plane of the cranial vertebral body and / or the three-dimensional orthogonal coordinate system. A step of acquiring vector image data of a plurality of fifth free curves conforming to the intersection of each of the plurality of planes parallel to the YY plane and the caudal end plate of the cranial vertebral body, and (4). ) The first and / or the second free curve and the third free curve based on the vector image data in a three-dimensional orthogonal coordinate system set independently of the three-dimensional X-ray projection image. , The fourth and / or the fifth free curve is rearranged, and the first plane including the first and / or the second free curve and the fourth and / or the fifth free curve are included. Based on the step of forming the second plane and (5) the vertebral body displacement information, the second plane is displaced with respect to the first plane in the three-dimensional orthogonal coordinate system, or the second plane is formed. The step of dislocating the first plane with respect to the second plane and arranging the first and second planes in a normal relative positional relationship, and (6) the first and second planes, respectively. The caudal and cranial end plates of the intervertebral spacers, and in the three-dimensional orthogonal coordinate system, the third free curve is oriented in the Z-axis direction between the caudal and cranial end plates of the intervertebral spacers. The side of the intervertebral spacer from the locus when moved to Provided is a method comprising forming a surface and sequentially performing the caudal and cranial endplate surfaces of the intervertebral spacer and the step of defining the intervertebral spacer from the side surface. ..

Here, a "free curve" is a curve having a start point, an end point, and at least one control point, which is mainly used in computer graphics to draw a curve or a straight line (when the control points overlap the start point or the end point). , Which is a straight line), and the coordinate values of points on the free curve are represented by one parameter (same below).
As the free curve, for example, a spline curve and a Bezier curve are known.

According to a preferred embodiment of the first invention, the third free curve is along the inner edge of each of the pair of hooked protrusions of the caudal vertebral body or along the bilateral edges of the intervertebral disc between the target vertebral bodies. A first line segment extending along the anterior edge inside the anterior edge of the intervertebral disc, and a third line segment extending along the posterior edge inside the posterior edge of the intervertebral disc. A line segment, a first arcuate portion connecting the first line segment and the second line segment adjacent to each other, and the first line segment and the third line segment adjacent to each other are connected. It consists of a second arcuate portion.

According to another preferred embodiment of the first invention, after performing step (6), (7) an axis extending posterior to the intervertebral spacer at a predetermined distance and parallel to the coronal plane. Is set to form the lateral expansion portion of the intervertebral spacer from the locus when the cranial end plate surface of the intervertebral spacer is rotated by a predetermined angle around the axis, and the intervertebral space after rotation is formed. The cranial end plate surface of the spacer is used as the new cranial end plate surface of the intervertebral spacer, the new cranial end plate surface of the intervertebral spacer, the caudal end plate surface of the intervertebral spacer, and the vertebrae. From the sides and lateral extensions of the interstitial spacer, the step of defining the modified intervertebral spacer is performed.

To solve the above problems, and according to the second invention, the relative displacement of the cranial and caudal vertebral bodies between the target vertebral bodies obtained from the three-dimensional X-ray projection image of the patient's spine. It is a program for designing an intervertebral spacer using the vertebral body displacement information regarding the above and vector image data of a plurality of free curves related to the cranial and caudal vertebral bodies, and is in the three-dimensional X-ray projection image. In a three-dimensional Cartesian coordinate system, the Z axis extends parallel to the midline, the XX plane extends parallel to one of the coronal and sagittal planes, and the YZ plane extends parallel to the coronal plane and the sagittal plane. Set to extend parallel to the other of the faces, the plurality of free curves are each of the plurality of planes parallel to the XX plane of the three-dimensional Cartesian coordinate system and the cranial side of the caudal vertebral body. A plurality of first free curves adapted to the intersection with the end plate, and / or each of a plurality of planes parallel to the YY plane of the three-dimensional Cartesian coordinate system and the cranial end of the caudal vertebral body. Determines the contours of a plurality of second free curves adapted to the intersection with the plate and the caudal end plate of the intervertebral spacer to be designed on a plane parallel to the XY plane of the three-dimensional Cartesian coordinate system. A third free curve, and a plurality of fourth planes adapted to the intersection of each of the plurality of planes parallel to the XX plane of the three-dimensional Cartesian coordinate system and the caudal end plate of the cranial vertebral body. And / or a plurality of fifth planes fitted to the intersection of each of the planes parallel to the YY plane of the three-dimensional Cartesian coordinate system and the caudal end plate of the cranial vertebral body. In a program consisting of a free curve, (1) the procedure for receiving the input of the vertebral body displacement information and the vector image data, and (2) the three-dimensional Cartesian coordinate system set independently of the three-dimensional X-ray projection image. The first and / or the second free curve, the third free curve, and the fourth and / or the fifth free curve are rearranged within the vector image data. The procedure for forming the first plane including the first and / or the second free curve and the second plane including the fourth and / or the fifth free curve, and (3) the vertebral body displacement information. Based on, in the three-dimensional Cartesian coordinate system, the second surface is displaced with respect to the first surface, or the first surface is displaced with respect to the second surface, and the first surface is displaced. And the procedure of arranging the second surface in a normal relative positional relationship, and (4) the first and second surfaces are the caudal end plate surface and the cranial end plate surface of the intervertebral spacer, respectively, and the tertiary. In the original Cartesian coordinate system, the third free curve is the intervertebral spacer. The side surface of the intervertebral spacer is formed from the locus when it is moved in the Z-axis direction between the caudal side and the cranial end plate surface of the intervertebral spacer, and the caudal side and the cranial end plate surface of the intervertebral spacer and the side surface thereof. A program is provided which comprises sequentially executing a procedure for defining the intervertebral spacer and a computer.

According to a preferred embodiment of the second invention, the third free curve extends along the inner edge of each of the pair of hooked protrusions of the caudal vertebral body or the bilateral edges of the intervertebral disc. A second line segment extending along the anterior edge medially to the anterior edge of the intervertebral disc between the subject vertebral bodies, and a third line segment extending along the posterior edge medially to the posterior edge of the intervertebral disc. A line segment, a first arcuate portion connecting the first line segment and the second line segment adjacent to each other, and the first line segment and the third line segment adjacent to each other are connected. It consists of a second arcuate portion.

According to another preferred embodiment of the second invention, after performing the procedure (4), (5) an axis extending posterior to the intervertebral spacer at a predetermined distance and parallel to the coronal plane. Is set to form the lateral expansion portion of the intervertebral spacer from the locus when the cranial end plate surface of the intervertebral spacer is rotated by a predetermined angle around the axis, and the intervertebral space after rotation is formed. The cranial end plate surface of the spacer is used as the new cranial end plate surface of the intervertebral spacer, the new cranial end plate surface of the intervertebral spacer, the caudal end plate surface of the intervertebral spacer, and the vertebrae. The computer is made to perform a procedure for defining the modified intervertebral spacer from the side surface and the lateral extension portion of the interstitial spacer.

According to the present invention, a three-dimensional orthogonal coordinate system is set in a three-dimensional X-ray projection image of the spine to acquire vertebral body displacement information, while each of a plurality of planes parallel to the XX plane and a target vertebral body. Multiple first free curves adapted to the intersection with the caudal end plate of the caudal vertebral body between, and / or the head of each of the multiple planes parallel to the YZ plane and the caudal vertebral body. Vector image data of a plurality of second free curves adapted to the intersection with the side end plate, and vector image data of a third free curve that determines the contour of the intervertebral spacer on a plane parallel to the XY plane. And a plurality of fourth free curves adapted to the intersection of each of the planes parallel to the XZ plane and the caudal end plate of the cranial vertebral body between the target vertebrates, and / or Y-. Vector image data of a plurality of fifth free curves conforming to the intersection of each of the plurality of planes parallel to the Z plane and the caudal end plate of the cranial vertebral body is acquired.

Next, the first to fifth free curves are rearranged based on the vector image data in the three-dimensional Cartesian coordinate system set independently of the three-dimensional X-ray projection image, and the first and / or the second freedom is performed. A first curved surface containing a curve is formed, a second curved surface including a fourth and / or a fifth free curve is formed, and the second surface is set with respect to the first surface based on the vertebral body displacement information. Displace or displace the first surface with respect to the second surface to place the first and second surfaces in a normal relative position.

The first and second planes are the caudal and cranial endplate planes of the intervertebral spacer, respectively, and the third free curve is the Z-axis between the caudal and cranial endplate planes of the intervertebral spacer, respectively. The lateral surface of the intervertebral spacer is formed from the locus when moved in the direction, and the intervertebral spacer is defined from the caudal and cranial endplate surfaces of the intervertebral spacer and the lateral surface, thereby forming the intervertebral spacer. Semi-custom made.

This semi-custom-made intervertebral spacer is designed based on a three-dimensional X-ray projection image of the patient's spine and fits the patient's body to a certain extent (no need to fit the patient's body to the intervertebral spacer). Therefore, a minimally invasive treatment can be realized for the patient.

In addition, the intervertebral spacer can be designed as long as the information on the posture of the patient at the time of imaging and the vector image data of the first to fifth free curves are acquired based on the three-dimensional X-ray projection image. Compared with the custom-made case, the cost and time required for designing the facet spacer can be significantly reduced.

In addition, disc deformation is corrected by correcting the relative cranial and caudal vertebral body displacement between target vertebral bodies in some patients with spinal injuries during the intervertebral spacer design phase. Intervertebral spacers to be corrected can be designed.

It is a flow chart of the intervertebral spacer design method according to 1 Example of this invention. It is a flow chart of the intervertebral spacer design method by another Example of this invention. It is a flow chart of the intervertebral spacer design program according to 1 Example of this invention. It is a flow chart of the intervertebral spacer design program according to another embodiment of this invention. (A) is a diagram showing an example of a three-dimensional X-ray projection image of the patient's spine, (B) is a tomographic image in a plane parallel to the sagittal plane of (A), and (C) is (A). ) Is a tomographic image on the coronal plane, and (D) is a tomographic image on the plane orthogonal to the midline of (A). It is a figure explaining the process of acquiring the vector image data of the 1st and 3rd free curves from the 3D X-ray projection image of FIG. It is a figure explaining the process of acquiring the vector image data of the 4th free curve from the 3D X-ray projection image of FIG. It is an enlarged view corresponding to the image of FIG. 6B. It is a figure explaining the process of designing an intervertebral spacer based on the 1st, 3rd and 4th free curves in a three-dimensional Cartesian coordinate system. It is a figure explaining the process of designing an intervertebral spacer based on the 1st, 3rd and 4th free curves in a three-dimensional Cartesian coordinate system. It is a figure explaining the process of designing an intervertebral spacer based on the 1st, 3rd and 4th free curves in a three-dimensional Cartesian coordinate system. It is a figure explaining the process of designing an intervertebral spacer based on the 1st, 3rd and 4th free curves in a three-dimensional Cartesian coordinate system. It is a figure explaining the process of designing an intervertebral spacer based on the 1st, 3rd and 4th free curves in a three-dimensional Cartesian coordinate system. It is a figure explaining the process of designing an intervertebral spacer based on the 1st, 3rd and 4th free curves in a three-dimensional Cartesian coordinate system. It is a figure explaining the process of designing an intervertebral spacer based on the 1st, 3rd and 4th free curves in a three-dimensional Cartesian coordinate system. It is a figure explaining the process of designing an intervertebral spacer based on the 1st, 3rd and 4th free curves in a three-dimensional Cartesian coordinate system. It is a figure explaining the process of designing an intervertebral spacer based on the 1st, 3rd and 4th free curves in a three-dimensional Cartesian coordinate system.

Hereinafter, the configuration of the present invention will be described with reference to the accompanying drawings based on preferred embodiments.
FIG. 1 is a flow chart of an intervertebral spacer design method according to an embodiment of the present invention.
With reference to FIG. 1, according to the method of the present invention, the three-dimensional orthogonal coordinate system XYZ extends in the three-dimensional X-ray projection image of the patient's spine with the Z axis parallel to the midline (match). The XX plane extends parallel to one of the coronal and sagittal planes (in this example, the coronal plane) (including the case where they match), and the YY plane is the coronal plane and the sagittal plane. It is set to extend parallel to (including the case of matching) the other of the sagittal planes (in this embodiment, the sagittal plane) (step S1 in FIG. 1), and then the target in the three-dimensional X-ray projection image. Acquire vertebral body displacement information regarding the relative displacement of the cranial and caudal vertebral bodies of the intervertebral disc (step S2 in FIG. 1).

FIG. 5A shows a three-dimensional X-ray projection image used in this embodiment. 5 (B) is a tomographic image on the plane parallel to the sagittal plane of FIG. 5 (A), and FIG. 5 (C) is a tomographic image on the coronal plane of FIG. 5 (A). D) is a tomographic image on a plane orthogonal to the midline of FIG. 5 (A).

With reference to FIG. 5, in this embodiment, the intervertebral bodies of the cervical vertebrae are between the vertebral bodies C5 and C6 of the cervical vertebrae, and an intervertebral spacer that replaces the intervertebral disc between the target vertebral bodies is designed.

The vertebral body displacement information is, in this embodiment, a measured value of the displacement of the caudal end plate of the caudal vertebral body C5 with respect to the cranial end plate of the caudal vertebral body C6.

This deviation is measured by a computer on which DICOM data (three-dimensional X-ray projection image data) can be handled by a known appropriate drawing software (VGStudio (registered trademark), VINCENT (registered trademark), ZIOstation (registered trademark), etc.). Based on the three-dimensional X-ray projection image displayed on the display of the computer, using a pointing device such as a mouse, the following is performed.
(1) The center of the cranial end plate of the caudal vertebral body C6 is set, and the first reference plane including the center is set on the cranial end plate. In addition, the _first auxiliary coordinate system X1 _- Y1-1 _- Z1 is set in the vertebral body C6 on the caudal side, the coordinate origin is located at the center, and the X1-1 _- Y1 plane is on the _first reference plane. _So that the X1 and Y1 axes are parallel to the X and Y axes, _respectively .
(2) The center of the caudal end plate of the cranial vertebral body C5 is set, and the second reference plane including the center is set on the caudal end plate. Further, a _second auxiliary coordinate system X2 _- Y2 _- Z2 is set in the vertebral body C5 on the cranial side, the coordinate origin is located at the center, and the X2 _- Y2 plane is on the _second reference plane. _The X2 axis and the _Y2 axis are located at the center in the left-right direction and the center in the anteroposterior direction of the caudal end plate, respectively.
(3) "The second reference plane is parallel to the first reference plane, and the center of the caudal end plate of the caudal vertebral body C5 is the center of the caudal end plate of the caudal vertebral body C6. The cranial vertebral body C5 is normal with respect to the caudal vertebral body C6 when located at a predetermined distance from the center of the cranial end plate on a perpendicular line extending perpendicular to the first reference plane. Criteria for "being in the same position", that is, "the X2 axis and the _Y2 axis are parallel to the X1 axis and the Y1 axis, _respectively , and the _{Z2 axis coincides with the Z1 axis, and the first and second axes are present} ." When the distance between the coordinate origins of the auxiliary coordinate system is _a predetermined length, the cranial vertebral body C5 is in the normal position with respect to the caudal vertebral body C6. " The tilt of the second reference plane with respect to the _first reference plane and the center and tail of the caudal end plate of the cranial vertebral body C5 in _each of the _1st plane, the Y1 _- Z1 plane and the X1 _- Y1 plane. The deviation between the centers of the cranial end plates of the lateral vertebral body C6 is measured.

Then, in the three-dimensional X-ray projection image of FIG. 5, the measured values of the deviation (vertebral body deviation information) are forward bending 5 degrees (deviation in the Y1 _- Z1 plane) and left bending ₁₀ degrees (X1 _- Z ₁ ). The deviation in the plane) and the left rotation of ₁₀ degrees (the deviation in the X1 _- Y1 plane) are acquired.
In this three-dimensional X-ray projection image, there is no deviation between the center of the caudal end plate of the cranial vertebral body C5 and the center of the caudal end plate of the caudal vertebral body C6.

In this embodiment, as the vertebral body displacement information, the displacement of the caudal end plate of the cranial vertebral body C5 with respect to the cranial end plate of the caudal vertebral body C6 was measured. The deviation of the cranial end plate of the caudal vertebral body C6 with respect to the caudal end plate may be measured and used as vertebral body deviation information.

According to the method of the present invention, each of a plurality of planes (which may include the XX plane) parallel to the XX plane of the three-dimensional orthogonal coordinate system XYZ and the caudal vertebral body are further obtained. Vector image data of a plurality of _first free curves L1 conforming to the intersection with the cranial end plate of C6, and / or a plurality of planes (YZ) parallel to the YZ plane of the three-dimensional orthogonal coordinate system. Vector image data of a plurality of _second free curves L2 conforming to the intersection of each of (which may include a plane) and the cranial end plate of the caudal vertebral body C6, and X of the three-dimensional orthogonal coordinate system. The vector image data of the _third free curve L3 that determines the contour of the intervertebral spacer to be designed on a plane parallel to the -Y plane (including the case on the XY plane) and parallel to the XY plane. Vector image data of a plurality of _fourth free curves L4 adapted to the intersection of each of the plurality of planes (which may include the XZ plane) and the caudal end plate of the cranial vertebral body C5. And / or fits the intersection of each of multiple planes (which may include the YZ plane) parallel to the YZ plane of the three-dimensional orthogonal coordinate system with the caudal end plate of the cranial vertebral body C5. The vector image data of the plurality of _fifth free curves L5 is acquired (step S3 in FIG. 1).

Here, a "free curve" is a curve having a start point, an end point, and at least one control point, which is mainly used in computer graphics to draw a curve or a straight line (when the control points overlap the start point or the end point). , Which is a straight line), and the coordinate values of points on the free curve are represented by one parameter.

As the free curve, for example, a spline curve and a Bezier curve are known. A Bezier curve is used in this embodiment.

In this embodiment, in order to simplify the explanation, only the vector image data of the first free curve L ₁ , the third free curve L ₃ and the fourth free curve L ₄ is acquired, and the second free curve is obtained. The vector image data of L ₂ and the fifth free curve L ₅ are not acquired.

The process of acquiring the vector image data of the _first and _third free curves L1 and L3 from the three-dimensional X-ray projection image is shown in FIGS. 6 (A) and 6 (B), respectively. Further, FIG. 7 shows a process of acquiring vector image data of the _fourth free curve L4 from the same image.

The _third free curve L3 is, as shown in FIG. 8, a first line segment d ₁ , d extending along the inner edge of each of the pair of hooked protrusions of the caudal vertebral body C6 or the bilateral edges of the intervertebral disc. ₁ and a second line segment d ₂ extending along the anterior edge medial to the anterior edge of the intervertebral disc, and a third line segment d ₃ extending along the posterior edge medial to the posterior edge of the intervertebral disc. The first arcuate portions d4 and d4 connecting the adjacent _first line segment d1 and the _second line segment d2, and the _first line segment d1 and the _third line segment _d adjacent to each other. It is composed of a second arcuate portion _d5 and _d5 connecting the _three .

In this case, the _third free curve L3, in particular the _second and _third line segments d2 and d3, is an area where contact between the intervertebral spacer and the nerves and blood vessels surrounding the vertebral body is reliably avoided. Determined to be located in. The shape of the figure defined by the _third free curve L5 is not limited to this embodiment.

The vector image data of the free curves L ₁ , L ₃ and L ₄ from the three-dimensional X-ray projection image is acquired as follows.
For example, when acquiring the vector image data of the _first free curve L1 in one plane parallel to the XZ plane, the tomographic image of the three-dimensional X-ray projection image displayed on the computer display in the one plane. In, the start point, the end point, and the control point of the _first free curve L1 are designated by using a pointing device.

As a result, as the vector image data of the _first free curve L1, the coordinate values of the start point, the end point, and the control point and the coordinate values of the points on the _first free curve L1 are determined (first). A parametric equation representing the free curve L ₁ ) is automatically acquired.
The method of acquiring the vector image data of the _third and _fourth free curves L3 and L4 is the same as this.

According to the method of the present invention, further, the first and / or the second free curves L ₁ , L based on the vector image data in the three-dimensional Cartesian coordinate system set independently of the three-dimensional X-ray projection image. ₂ , the _third free curve L3, and the _fourth and / or _fifth free curves L4, L5 are rearranged to include the _first and / or _second free curves L1, L2. A _first surface F1 and a _second surface F2 including the _fourth and / or _fifth free curves L4, L5 are formed (step S4 in FIG. 1).

In this embodiment, since the vector image data of the _second and _fifth free curves L2 and L5 are not acquired in step S3, the _second and _fifth free curves L2 and L5 are omitted in step S4. ..

Next, based on the vertebral body displacement information, the second surface F ₂ is displaced with respect to the first surface F ₁ in the three-dimensional Cartesian coordinate system, and the first and second surfaces F ₁ and F ₂ are normal. Arrange in a relative positional relationship (step S5 in FIG. 1).

In this case, instead of displacing the second surface F ₂ with respect to the first surface F ₁ , the first surface F ₁ may be displaced with respect to the second surface F ₂ .

According to the method of the present invention, the first and second surfaces F ₁ and F ₂ are further set as the caudal end plate surface E ₂ and the cranial end plate surface E ₁ of the intervertebral spacer M, respectively, and have three-dimensional Cartesian coordinates. In the system, the side surface E ₃ of the intervertebral spacer M from the locus when the third free curve L ₃ is moved in the Z-axis direction between the caudal and cranial endplate surfaces E ₂ and E ₁ of the intervertebral spacer M. Is formed, and the intervertebral spacer M is defined from the caudal and cranial end plate surfaces E ₂ , E ₁ and the side surface E ₃ of the intervertebral spacer M (step S6 in FIG. 1).

Steps S4 to S6 can be performed using any known and suitable 3D modeling software.
In this embodiment, the plug-in "Grasshopper (registered trademark)" of the 3D modeling software "Rhinoceros (registered trademark)" is used, and a computer on which "Rhinoceros (registered trademark)" and "Grasshopper (registered trademark)" are installed is installed. Run with.

Hereinafter, steps S4 and S5 will be specifically described.
(1) First, as shown in FIG. 9, the first, third, and fourth free curves L ₁ , L ₃ , and L ₄ are rearranged in the three-dimensional Cartesian coordinate system based on the vector image data.
(2) Next, as shown in FIG. 10, using the loft command of the software, the first surface (surface) F ₁ including the first free curve L ₁ and the fourth free curve L ₄ are included. A second surface (surface) F ₂ is formed.
For example, the _first surface F1 is automatically formed by using a pointing device to select all the _first free curves L1 on the display and then executing a loft command.

The surface formed by the loft command is called a NURBS curved surface, and the NURBS curved surface is a kind of parametric curved surface. Have. Then, by changing this parameter value, the NURBS curved surface can be represented on the three-dimensional Cartesian coordinate system.

(3) Further, as shown in FIG. 11, the center of the _first surface F1 is set, and the first reference plane (not shown) including the center is set on the _first surface F1. Further, the _first auxiliary coordinate system X1 _- Y1-1 _- Z1 is set on the _first surface F1, the coordinate origin is located at the center, and the X1 _- Y1 plane is on the _first reference plane. _So that the X1 and Y1 axes are parallel to the X and Y axes, _respectively .
(4) Further, the center of the second surface F ₂ is set, and the second reference plane (not shown) including the center is set on the second surface F ₂ . Further, a _second auxiliary coordinate system X2 _- Y2 _- Z2 is set on the _second surface F2, the coordinate origin is located at the center thereof, and the X2 _- Y2 plane is on the _second reference plane. _The X2 axis and the Y2 axis are located at the center in the left-right direction and the center in the front-back direction of the _second reference plane, respectively.

(5) Spinal body displacement information "Forward bending 5 degrees (deviation in the Y1 _- Z1 plane), left flexion ₁₀ degrees (deviation in the X1 _- Z1 plane), counterclockwise rotation ₁₀ degrees (deviation in the X1 _{- Y1} plane) Based on "deviation)", the second reference plane ( _second plane F2) is rotated 5 degrees clockwise with respect to the X2 axis (see _FIG . 12, corrected by 5 degrees forward bending), and then the second reference. Rotate the plane (second plane F ₂ ) 10 degrees clockwise with respect to the Y2 axis (see _FIG . 13, modified by 10 degrees to the left), and then rotate the second reference plane (second plane F ₂ ). Rotate 10 degrees clockwise with respect to the Z ₂ -axis (see Fig. 14, correction of 10 degrees left rotation).
(6) Thereby, the first and second surfaces F ₁ and F ₂ are arranged in a normal relative positional relationship. Then, the first and second surfaces F ₁ and F ₂ at this time are designated as the caudal end plate surface E ₂ and the cranial end plate surface E ₁ of the intervertebral spacer M, respectively.

(7) After that, as shown in FIG. 15, the locus when the third free curve L ₃ is moved in the Z-axis direction between the caudal and cranial endplate surfaces E ₂ and E ₁ of the intervertebral spacer M. Form the side surface _E3 of the intervertebral spacer M from.
(6) Then, the intervertebral spacer M is defined from the cranial end plate surface E ₁ , the caudal end plate surface E ₂ , and the side surface E ₃ of the intervertebral spacer (see FIG. 16).

Then, after the image formation (design) of the intervertebral spacer M is completed, the obtained design data is converted into three-dimensional modeling data (for example, STL data) by this software and output as a file.

Thus, according to the present invention, the intervertebral spacer can be semi-custom-made. And this semi-custom-made intervertebral spacer is designed based on the three-dimensional X-ray projection image of the patient's spine, to a certain extent on the patient's body (to the extent that the patient's body does not need to be fitted to the intervertebral spacer). Since it is compatible, a minimally invasive procedure can be realized for the patient.

In addition, the intervertebral spacer can be designed as long as the information on the posture of the patient at the time of imaging and the vector image data of the first to fifth free curves are acquired based on the three-dimensional X-ray projection image. Compared with the custom-made case, the cost and time required for designing the facet spacer can be significantly reduced.

In addition, disc deformation is corrected by correcting the relative cranial and caudal vertebral body displacement between target vertebral bodies in some patients with spinal injuries during the intervertebral spacer design phase. Intervertebral spacers to be corrected can be designed.

It should be noted that the designed intervertebral spacer M may be further modified in consideration of the anteroposterior tilting motion between the target vertebral bodies.
Then, in the case of making a correction in consideration of the backward tilting motion, after sequentially executing steps S1 to S6 in FIG. 1, a point further separated behind the intervertebral spacer M by a predetermined distance as shown in FIG. When the axis (axis parallel to the X-axis) V extending parallel to the coronal plane is set and the cranial end plate surface E1 of the intervertebral spacer M is rotated by _a predetermined angle around the axis V. The lateral expansion portion E4 of the intervertebral spacer M is formed from the locus, and the cranial end plate surface S1 of the intervertebral spacer M after rotation is designated as _a new cranial end plate surface E _1'of the _{intervertebral} spacer M. Modified intervertebral space from the new cranial end plate surface E _1'of the intervertebral spacer, the caudal end plate surface E ₂ of the intervertebral spacer, and the side surface E ₃ and lateral dilation portion E ₄ of the intervertebral spacer. The spacer M'is defined (designed) (step S7 in FIG. 2).

In this case, the set position of the axis V and the rotation angle around the axis V are the degree of modification required (individual patient subject), for example, rotating 30 degrees at a position 20 to 60 mm posterior to the disc axis. It depends on the condition of the vertebral body, etc.).

FIG. 3 is a flow chart of an intervertebral spacer design program according to an embodiment of the present invention.
The intervertebral spacer design program of the present invention includes vertebral body displacement information regarding the relative displacement of the cranial and caudal vertebral bodies between target vertebral bodies obtained from a three-dimensional X-ray projection image of the patient's spine. Intervertebral spacers are designed using vector image data of multiple free curves related to the cranial and caudal vertebral bodies.

In this case, the acquisition of the vertebral body displacement information from the three-dimensional X-ray projection image and the acquisition of the vector image data of the free curve are performed by sequentially executing steps S1 to S3 of the intervertebral spacer design method of the present invention described above. Will be done.

That is, in the intervertebral spacer design program of the present invention, the vector image data of the first to fifth free curves described above is used.

With reference to FIG. 3, according to the present invention, a computer is made to receive input of vertebral body displacement information and vector image data of the first to fifth free curves (procedure P1 of FIG. 3).

Next, the computer is made to set the three-dimensional Cartesian coordinate system independently of the three-dimensional X-ray projection image, and the first and / or second free curve is set in the three-dimensional Cartesian coordinate system based on the vector image data. And, the third free curve and the fourth and / or the fifth free curve are rearranged, and the first surface including the first and / or the second free curve, and the fourth and / or the fifth. A second surface including the free curve of is formed (procedure P2 in FIG. 3).

Then, based on the vertebral body displacement information, the second surface is displaced with respect to the first surface in the three-dimensional Cartesian coordinate system, and the first and second surfaces are arranged in a normal relative positional relationship on the computer. (Procedure P3 in FIG. 3).

In this case, instead of displacing the second surface with respect to the first surface, the first surface may be displaced with respect to the second surface.

Further, in the computer, the first and second planes are the caudal and cranial endplate planes of the intervertebral spacer, respectively, and in the three-dimensional Cartesian coordinate system, the third free curve is the caudal side of the intervertebral spacer. And the lateral surface of the intervertebral spacer is formed from the locus when moved in the Z-axis direction between the cranial endplate surfaces, and the caudal and cranial endplate surfaces of the intervertebral spacer and the lateral surface of the intervertebral spacer are used as vertebrae. The inter-spacer is defined (procedure P4 in FIG. 3).

In addition, it may be desired to further modify the intervertebral spacer designed by the computer in consideration of the anterior-posterior tilting motion between the target vertebral bodies.
Then, for example, in the case of making corrections in consideration of the backward tilting motion, after performing the procedures P1 to P4 in sequence, the computer further passes through a point behind the facet spacer at a predetermined distance and forms a coronal surface. By setting an axis that extends in parallel, the lateral extension of the intervertebral spacer is formed from the trajectory when the cranial end plate surface of the intervertebral spacer is rotated by a predetermined angle around the axis, and the post-rotation vertebrae. The cranial end plate surface of the intervertebral spacer is used as the new cranial end plate surface of the intervertebral spacer, the new cranial end plate surface of the intervertebral spacer, the caudal end plate surface of the intervertebral spacer, and the intervertebral spacer. A modified intervertebral spacer is defined (designed) from the lateral surface and the lateral extension portion (procedure P5 in FIG. 4).

In this case, the set position of the axis and the rotation angle around the axis are the degree of modification required (individual patient's target vertebral body), for example, rotating 30 degrees at a position 20 to 60 mm posterior to the disc axial plane. It depends on the state of)).

Although the preferred embodiment of the present invention has been described above, the configuration of the present invention is not limited to the above embodiment, and those skilled in the art devise various modifications within the scope of the configuration described in the claims of the present application. Needless to say, you will get it.

For example, in the above embodiment, the intervertebral spacer was designed with one interbody of the cervical vertebra as the target interbody, but according to the present invention, other components of the spine (as in the above embodiment). Intervertebral spacers between the vertebral bodies of the thoracic spine, lumbar spine, etc.) can be designed.

Further, in the above embodiment, the present invention is based on the present invention with no deviation between the center of the caudal end plate of the cranial vertebral body and the center of the caudal end plate of the caudal vertebral body, and the tail of the cranial vertebral body. Although applied when only the tilt deviation of the lateral end plate with respect to the center of the caudal end plate occurs, the present invention applies to the center of the caudal end plate of the cranial vertebral body and the head of the caudal vertebral body. It is also applicable when both the center-to-center shift of the lateral end plate and the tilt deviation of the caudal end plate of the cranial vertebral body with respect to the center of the caudal end plate occur.

C5 Cranial vertebral body C6 Caudal vertebral body d ₁ Inner edge of hooked protrusion or side edge of intervertebral disc d ₂ Second line segment d ₃ Third line segment d ₄ First arcuate part d ₅ Second Arc-shaped part E ₁ Cranial end plate surface of the intervertebral spacer E _1'New cranial end plate surface of the intervertebral spacer E ₂ Caudal end plate surface of the intervertebral spacer E ₃ Side surface of the intervertebral spacer E ₄ vertebrae Extended side surface portion of interspacer F ₁ First surface F ₂ Second surface L ₁ First free curve L ₂ Second free curve L ₃ Third free curve L ₄ Fourth free curve L ₅ Fifth Free curve M Intervertebral spacer M'Modified intervertebral spacer V Axis parallel to coronal plane (axis parallel to X axis)

Claims (6)

A method of designing intervertebral spacers,
(1) In the 3D X-ray projection image of the patient's spine, the 3D orthogonal coordinate system extends parallel to the midline of the Z axis, and the XX plane is parallel to one of the coronal plane and the sagittal plane. The step of setting the extension and the YY plane to extend parallel to the other of the coronal plane and the sagittal plane, and
(2) A step of acquiring vertebral body displacement information regarding the relative displacement of the cranial and caudal vertebral bodies between the target vertebral bodies in the three-dimensional X-ray projection image, and
(3) A plurality of first free curves conforming to the intersection of each of the plurality of planes parallel to the XX plane of the three-dimensional orthogonal coordinate system and the cranial end plate of the caudal vertebral body, and a plurality of first free curves. / Or a vector image of a plurality of second free curves adapted to the intersection of each of the plurality of planes parallel to the YZ plane of the three-dimensional orthogonal coordinate system and the cranial end plate of the caudal vertebral body. Data, vector image data of a third free curve that determines the contour of the intervertebral spacer to be designed on a plane parallel to the XY plane of the three-dimensional orthogonal coordinate system, and the three-dimensional orthogonal coordinate system. A plurality of fourth free curves adapted to the intersection of each of the plurality of planes parallel to the XX plane and the caudal end plate of the cranial vertebral body, and / or Y of the three-dimensional orthogonal coordinate system. -A step of acquiring vector image data of a plurality of fifth free curves conforming to the intersection of each of the plurality of planes parallel to the Z plane and the caudal end plate of the cranial vertebral body.
(4) In the three-dimensional Cartesian coordinate system set independently of the three-dimensional X-ray projection image, the first and / or the second free curve and the third freedom are based on the vector image data. The curve and the fourth and / or the fifth free curve are rearranged, and the first surface including the first and / or the second free curve and the fourth and / or the fifth free curve are rearranged. And the steps to form the second surface, including
(5) Based on the vertebral body displacement information, in the three-dimensional Cartesian coordinate system, the second surface is displaced with respect to the first surface, or the first surface is displaced with respect to the second surface. And the step of arranging the first and second surfaces in a normal relative positional relationship.
(6) The first and second surfaces are the caudal end plate surface and the cranial end plate surface of the intervertebral spacer, respectively, and in the three-dimensional Cartesian coordinate system, the third free curve is the intervertebral spacer. The side surface of the intervertebral spacer is formed from the locus when moved in the Z-axis direction between the caudal side and the cranial end plate surface of the intervertebral spacer, and the caudal side and the cranial end plate surface of the intervertebral spacer and the side surface thereof. A method characterized by sequentially executing the steps of defining the intervertebral spacer from and to the step. The third free curve extends along the inner edge of each of the pair of hooks of the caudal vertebral body or along the bilateral edges of the intervertebral disc between the target vertebral discs, and the anterior segment of the intervertebral disc. A second line segment extending along the anterior edge on the medial side of the edge, a third line segment extending along the posterior edge on the medial side of the posterior edge of the intervertebral disc, and the first line segment adjacent to each other. It is composed of a first arc-shaped portion connecting the segment and the second line segment, and a second arc-shaped portion connecting the first line segment and the third line segment adjacent to each other. The method according to claim 1, wherein the method is characterized by the above. After executing the step (6),
(7) An axis extending behind the intervertebral spacer at a predetermined distance and extending parallel to the coronal surface is set, and the cranial end plate surface of the intervertebral spacer is set around the axis. The lateral expansion portion of the intervertebral spacer is formed from the locus when rotated at an angle, and the cranial end plate surface of the intervertebral spacer after rotation is used as a new cranial end plate surface of the intervertebral spacer. Steps to define the modified intervertebral spacer from the new cranial endplate surface of the intervertebral spacer, the caudal endplate surface of the intervertebral spacer, and the lateral and lateral dilations of the intervertebral spacer. The method according to claim 1 or claim 2, wherein the method is performed. Vertebral displacement information regarding the relative displacement of the cranial and caudal vertebral bodies between the target vertebral bodies obtained from a three-dimensional X-ray projection image of the patient's spine, and the cranial and caudal vertebral bodies. A program for designing intervertebral spacers using vector image data of multiple related free curves.
In the three-dimensional X-ray projection image, the three-dimensional orthogonal coordinate system extends parallel to the midline of the Z axis, the XX plane extends parallel to one of the coronal plane and the sagittal plane, and the YZ plane extends. Is set to extend parallel to the other of the coronal plane and the sagittal plane.
The plurality of first free curves are adapted to the intersection of each of the plurality of planes parallel to the XX plane of the three-dimensional orthogonal coordinate system and the cranial end plate of the caudal vertebral body. A free curve and / or a plurality of second freedoms adapted to the intersection of each of the planes parallel to the YZ plane of the three-dimensional orthogonal coordinate system and the cranial end plate of the caudal vertebral body. A third free curve that determines the contour of the intervertebral spacer to be designed on a plane parallel to the XY plane of the three-dimensional orthogonal coordinate system, and the XX plane of the three-dimensional orthogonal coordinate system. A plurality of fourth free curves adapted to the intersection of each of the plurality of planes parallel to the cranial vertebral body and / or the YZ plane of the three-dimensional orthogonal coordinate system. In a program consisting of a plurality of fifth free curves adapted to the intersection of each of the parallel planes with the caudal end plate of the cranial vertebral body.
(1) A procedure for receiving input of the vertebral body displacement information and the vector image data, and
(2) In the three-dimensional Cartesian coordinate system set independently of the three-dimensional X-ray projection image, the first and / or the second free curve and the third freedom are based on the vector image data. The curve and the fourth and / or fifth free curve are rearranged, the first surface including the first and / or second free curve, and the fourth and / or fifth free curve. And the procedure for forming the second surface, including
(3) Based on the vertebral body displacement information, in the three-dimensional Cartesian coordinate system, the second surface is displaced with respect to the first surface, or the first surface is displaced with respect to the second surface. And the procedure of arranging the first and second surfaces in a normal relative positional relationship.
(4) The first and second surfaces are the caudal end plate surface and the cranial end plate surface of the intervertebral spacer, respectively, and in the three-dimensional Cartesian coordinate system, the third free curve is the intervertebral spacer. The side surface of the intervertebral spacer is formed from the locus when it is moved in the Z-axis direction between the caudal side and the cranial end plate surface of the intervertebral spacer, and the caudal side and the cranial end plate surface of the intervertebral spacer and the side surface thereof. A program characterized in that the procedure for defining the intervertebral spacer is sequentially executed by a computer. The third free curve extends along the inner edge of each of the pair of hooks of the caudal vertebral body or along the bilateral edges of the intervertebral disc between the target vertebral discs, and the anterior segment of the intervertebral disc. A second line segment extending along the anterior edge on the medial side of the edge, a third line segment extending along the posterior edge on the medial side of the posterior edge of the intervertebral disc, and the first line segment adjacent to each other. It is composed of a first arc-shaped portion connecting the segment and the second line segment, and a second arc-shaped portion connecting the first line segment and the third line segment adjacent to each other. The program according to claim 4, wherein the program is characterized by the above. After executing the above procedure (4),
(5) An axis extending behind the intervertebral spacer at a predetermined distance and extending parallel to the coronal surface is set, and the cranial end plate surface of the intervertebral spacer is set around the axis. The lateral expansion portion of the intervertebral spacer is formed from the locus when rotated at an angle, and the cranial end plate surface of the intervertebral spacer after rotation is used as a new cranial end plate surface of the intervertebral spacer. A procedure for defining a modified intervertebral spacer from a new cranial endplate surface of the intervertebral spacer, a caudal endplate surface of the intervertebral spacer, and lateral and lateral dilations of the intervertebral spacer. The program according to claim 4 or 5, wherein the computer is executed.

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