JP2006255039A - Vertebra instability measuring implement - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small and robust measuring implement having simple constitution which can speedily and easily measure instability between vertebras and which holds stability of the material against high-temperature sterilization treatment. <P>SOLUTION: A method for measuring the instability degree between the vertebras is characterized in that two small holes for inserting pins into the spinous process are formed at spur parts of the vertebras and the pins are inserted into the holes. Next, in the state where a spring is compressed to a maximum degree, a spring support and pin insertion conduit tubes fixed to both of its ends and the hole 71 and the pin guiding groove 72 of a measurement plate are combined for inserting the pins. In this case, when the space between the vertebras is stable, the pins overcome the separation force of the springs and moves little. When the space between the vertebras is instable on the other hand, the pins never overcome the separation force of the springs, so that the pins move along the guiding groove. Then, the moving amount is measured to accurately measure the instability degree. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a measuring instrument for easily and objectively measuring instability between vertebrae, particularly lumbar vertebrae, for the purpose of treating spinal diseases.

Structures such as the spine and intervertebral discs protect the spinal cord, which is a central nervous system, and at the same time are components of the human body that are involved in exercise, and spinal defects often involve great inconvenience in daily life. Here, FIG. 1 shows an overall view of the lumbar vertebra, and FIG. 2 shows a top view of the second lumbar vertebra.
Injuries are likely to occur in the spine due to aging, inflammation, tumors, trauma, and the like, and in particular, diseases such as intervertebral disc herniation, spinal canal stenosis, degenerative spondylosis, and isolated spondylosis develop in the lumbar spine.

In such diseases and gradual pressure surgery during surgery, the spine is often unstable. In addition, a bone graft or a fixation technique (instrumentation) using a metal is performed on the unstable spine. However, fixing the vertebrae and restricting the degree of freedom does not fully demonstrate the essential functions of the vertebrae, so objectively determine whether vertebral fixation is necessary depending on the instability of the spine. Must be judged.

  On the other hand, the present inventor has previously developed an instability measuring tool that can quickly and easily measure instability between vertebrae (Patent Document 1). This measuring instrument uses a method of measuring instability with a strain gauge (Fig. 3), and it can objectively measure instability between vertebrae, but the measurement system becomes large due to the use of a static strain meter. In addition, there is a problem that the material properties cannot be kept constant with respect to the process of sterilizing the measuring tool at a high temperature in an autoclave.

Japanese Patent No. 3288038

In view of the above circumstances, the subject of the present invention is that the instability between the vertebrae can be quickly and easily, and the instability measuring instrument between the vertebrae is simple and has a small structure while maintaining the stability of the material against high-temperature sterilization. Is to provide.

  In order to solve the above-mentioned problems, the present inventors have come up with the idea that the instability of the spine can be measured by locking the pin to the spinous process portion of the spine and applying a separation force between the pins. Reached.

Specifically, the first aspect of the present invention includes two pins for locking to the spinous processes of adjacent vertebrae, means for providing a separation force between the two pins and the pins, The present invention relates to an instrument for measuring instability between vertebrae having means for measuring a moving distance between pins. Next, according to a second aspect of the present invention, means for applying a separating force to the pin includes a spring, a support body that holds the spring straight, and pin insertion conduits fixed to both ends of the support body. A pin insertion hole for fixing one of the two pins, and a pin guide groove for moving the other pin apart according to instability between the vertebrae. The present invention relates to an instability measuring instrument between vertebrae, characterized by comprising a measuring plate provided.

In the above, the method of locking the pin to the spinous process portion of the spine is that the small hole for inserting the pin is formed in the spinous process portion, and the method of inserting the pin into the small hole can integrate the pin and the spinous process portion. So most desirable. Next, there are a leaf spring, a coil spring, and the like as a spring for giving a separation force, but a coil spring is generally used in terms of accuracy, light weight, and cost. Further, the pin insertion conduit fixed to both ends of the spring support needs to have a structure for holding the two pins in parallel with each other. Next, for the measurement plate, a pin insertion hole for inserting and fixing one of the two pins, and a pin guide groove for moving the other pin according to the degree of instability of the spine are measured. It is provided in the board. Here, the amount of movement of the pin can be determined by visual measurement, but a specific amount of movement can be measured by attaching a measurement scale to the guide groove of the measurement plate, and accurate information can be obtained by determining the degree of spinal instability. Given.

  Next, a third aspect of the present invention is characterized in that the materials of the pins, springs, and measurement plate for constituting the instability measuring tool are all corrosion-resistant metals. Since this device is used for treatment of the spine of a human body, a material that adversely affects human tissue is not allowed. Corrosion-resistant metals such as stainless steel and titanium are generally used for the implant material and the artificial bone. However, since titanium is expensive in terms of raw material cost and poor in workability, stainless steel is generally used. Thereby, it does not cause a material change even in the autoclave sterilization treatment at a temperature of about 100 ° C. or higher, and it is preferably used.

  The intervertebral instability measuring instrument of the present invention has a small, light, robust and simple structure, and the material is highly stable against heat changes such as sterilization. Since the measurement method is also simple and objective measurement values can be obtained, it is possible to determine with high reliability whether or not the spinal surgery is necessary.

  Although embodiments of the present invention will be described below, the technical scope of the present invention is not limited by the following embodiments, and various modifications can be made without changing the gist of the present invention. Further, the technical scope of the present invention extends to an equivalent range.

  FIG. 4 shows an overall configuration diagram (side view) of the measuring instrument after assembly. Hereinafter, each component will be described with reference to the drawings. FIG. 5 shows an insertion pin, which is generally a round bar having a diameter of 2 to 3 mmφ and a length of 30 to 40 mm. And the front-end | tip part of the pin inserted in a spinous process part is processed into the triangular pyramid shape by the taper of about 60 degrees.

  FIG. 6 shows a coil spring 61 for applying a separating force, supports 62A and 62B for supporting the coil spring inside thereof, and pin insertion conduits 63 fixed to both ends thereof. Here, the spring support is divided into two parts as shown in 62A and 62B, and both are generally processed into a predetermined shape by cutting from a metal bar. And 62A and 62B are mutually nested, and have a structure that can be slid by the separating force of the spring. Here, the pin insertion conduit 63 may be processed integrally with the spring support during cutting from the metal rod, or after the pin insertion conduit and the spring support are processed separately, they are integrated by welding or the like. Also good.

Next, FIG. 7 shows a measurement plate. One of the two pins has a hole 71 for fixing the pin and a guide groove capable of sliding the other pin along the guide groove 72. It has a structure.
Since the average distance between adjacent spinous processes in Japan is about 25 mm, the distance between pins when the spring is fully compressed is about 25 mm, and the distance between the spines is most unstable. The shape of the guide groove and the measurement plate is determined by setting the slide length of the pin to about 20 mm.

Here, a method for measuring the degree of instability between vertebrae by the device of the present invention will be described. First, two small holes for inserting a pin are formed in the spinous process portion of the adjacent spine to be measured, and the pin is inserted into the hole. Next, in a state where the spring is compressed to the maximum extent, the spring support, the pin insertion conduit fixed to both ends thereof, the hole 71 of the measurement plate, and the pin guide groove 72 are combined and inserted into the pin. Here, if the distance between the vertebrae is stable, there is almost no movement of the pin overcoming the separation force of the spring. On the other hand, if the spine is unstable, the spring separation force cannot be overcome and the pin moves along the guide groove. Then, the amount of movement is measured to objectively measure spinal instability.

Humans with various vertebrae (normal, intervertebral disc damage, interspinous / supraspinal ligament resection, right facet joint resection, bilateral joint resection, posterior longitudinal ligament resection, posterior intervertebral disc resection, resection of only the anterior longitudinal ligament) Using the intervertebral instability measuring instrument according to the present invention on the corpse lumbar spine, the function of the measuring instrument was confirmed. Here, the material of the pin, the coil spring support, the pin insertion conduit, and the measurement plate was SUS316, and the material of the coil spring was SUS304. Moreover, the length of the pin was 36.5 mm and the diameter was 2.5 mm, and the tip part inserted into the small hole of the spinous process was processed into a triangular pyramid shape. Next, a coil spring having an outer diameter and an average diameter of 10.0 mm and 9.2 mm, an effective number of turns of 9.50, and a spring constant of 0.481 N / mm was used. The cylinder part of the coil spring support has an outer diameter of 8.4 mm, and the core cross section inserted into the outer cylinder is a square with a side of 4 mm, the length of the pin insertion conduit is 15 mm, and the diameter of the pin insertion part is It was set to 2.7 mm.
Next, the length of the measurement plate was 51.3 mm, the width was 7 mm, the thickness was 1.5 mm, the pin hole diameter was 2.7 mm, and the guide groove width and length were 2.7 mm and 19.5 mm, respectively.

The results of measuring the instability of the spine by the above test are shown in Table 1. The intervertebral instability measuring instrument according to the present invention has a function that the inter-pin movement distance varies according to the instability between the spines and functions suitably. It was confirmed.

It is an outline figure showing the whole picture of the lumbar left side. It is a schematic diagram which shows the upper surface of a 2nd lumbar vertebra. It is a figure which shows the apparatus by invention of a prior application patent. It is a schematic diagram showing the whole picture of the present invention. It is the schematic which shows the pin in this invention. It is the schematic which shows the coil spring and its support body in this invention, and a pin insertion conduit. It is the schematic which shows the upper surface and side surface of the measurement board in this invention.

Explanation of symbols

61 coil spring 62A, 62B support 63 pin insertion conduit 71 pin fixing hole 72 pin guide groove

Claims (3)

  Two pins for locking to the spinous processes of adjacent vertebrae, means for providing a separation force between the two pins, and means for measuring a moving distance between the pins An instrument for measuring instability between vertebrae.   In the above, the means for applying a separating force to the pin is composed of a spring, a support body that holds the spring straight, and pin insertion conduits fixed to both ends of the support body, and the moving distance between the pins The measuring means is composed of a pin insertion hole for fixing one of the two pins, and a measurement plate provided with a pin guide groove for moving the other pin apart according to instability between the spines. 2. The intervertebral instability measuring instrument according to claim 1. 3. The intervertebral body according to claim 1 and / or 2, wherein the material of the pin, the spring and its support, the pin insertion conduit, and the measuring plate constituting the instability measuring device is a corrosion-resistant metal. Instability measuring instrument.

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