JP3660696B2 - Spinous process spacer - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a spinous process spacer that divides a spinous process (including a vertebral arch) of a cervical spine into two in the midline and inserts and fixes between the divided spinous processes.
[0002]
[Prior art and its problems]
In order to remove the damage caused by compression of the spinal cord due to cervical spondylotic myelopathy or posterior longitudinal ligament ossification of the cervical spine, spinal canal dilation has been performed conventionally, and spinous process vertical split method is often performed, and has already been established. It has become a surgical method. In this method, a bone fragment collected from the iliac bone was conventionally mounted between the vertically divided spinous processes. However, since the burden of collecting the iliac bone is given to the patient, only a horizontal section at the time of wearing is recently used. Attempts have been made to use ceramic block-like bodies having a trapezoidal shape.
However, this conventional product cannot be said to be suitable for the actual shape of the divided spinous processes, and is not very suitable for the gap between the divided spinous processes, resulting in bone resorption or spacers. The cervical vertebrae movement was sometimes disturbed by contact with each other.
[0003]
OBJECT OF THE INVENTION
An object of the present invention is to provide a spinous process spacer that is excellent in compatibility with a divided spinous process, does not cause bone resorption after fixation, does not contact adjacent spacers, and does not inhibit cervical spine movement. .
[0004]
SUMMARY OF THE INVENTION
In the present invention, as a result of observing the enlarged state of the divided spinous processes in spinal canal enlargement, when the divided spinous processes are opened and the spinal canal is enlarged, the head (upper) side and the tail (lower) side are uniform. It was made by discovering the fact that the head side is wider than the caudal side without expanding.
That is, the spinous process spacer of the present invention used for expanding the spinal canal by inserting it between the vertically divided spinous processes has a substantially trapezoidal shape with a narrow width on the spinal canal side in the horizontal section, and is divided. The longitudinal forehead cross section between the spinous processes has a substantially trapezoidal block shape with a wide width on the head side, and the cross-sectional trapezoidal shape in the horizontal cross section and the forehead cross section is short from the long side. The angle between both ends reaching the side is 40 ° or more and less than 85 °, and is characterized by being made of a biocompatible ceramic material.
In addition, the spinous process spacer is positioned on the outside of the spinal canal in the horizontal direction in the horizontal section, and a flange located outside the split spinous process is provided as a single unit to prevent falling into the spinal canal more reliably. can do.
[0005]
As the biocompatible ceramic material constituting the spinous process spacer of the present invention, glass ceramics or a calcium phosphate compound having a Ca / P ratio of 1.0 to 2.0 is preferable. Examples of calcium phosphate compounds having a Ca / P ratio of 1.0 to 2.0 that can be used in the present invention include various types of apatite such as hydroxyapatite and fluorine apatite, primary calcium phosphate, dicalcium phosphate, tricalcium phosphate, and phosphoric acid. Tetracalcium and the like can be mentioned, and these can be used alone or as a mixture. After the slurry of the raw material compound is dried, calcined at 500 to 800 ° C. and then calcined at 800 to 1400 ° C., and the obtained block-like body is processed into a desired shape and size, or the calcium phosphate compound A green compact having a desired shape and size is produced from the powder, and this is fired in the same manner as described above.
[0006]
In the present invention, at least the surface portion of the spinous process spacer is composed of a biocompatible porous ceramic, so that the affinity with the surrounding bone tissue is good, and bone fusion is promoted by the penetration of the bone tissue into the pores. The The porous ceramic preferably has continuous pores. Although there is no restriction | limiting in particular in the pore diameter and porosity, Usually, it is preferable that a pore diameter is 2-2000 micrometers, and a porosity is 30-80%, Preferably it is 40-70%.
[0007]
The central portion may be composed of dense or porous ceramics, and examples of usable ceramics include calcium phosphate compounds having a Ca / P ratio of 1.0 to 2.0, alumina, titania, zirconia, and the like. Of these, calcium phosphate compounds are preferred. There is no particular limitation on the method of providing a porous biocompatible material layer on the surface of the central part made of dense ceramics, and any known method can be adopted, for example, thermal spraying, sputtering, impregnation. Method, spray coating method and the like.
[0008]
As described above, the spinous process spacer of the present invention is only required to be composed of biocompatible porous ceramics at least on the surface portion, but is preferably composed of porous ceramics having biocompatibility as a whole.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described in detail based on examples with reference to the drawings.
FIGS. 1 to 4 show a first embodiment of a spinous process spacer 10 according to the present invention, and FIGS. 5 to 7 show spinal canal enlargement performed by dividing the spinous process of the cervical spine and the spinous process spacer. The insertion state of the spacer 10 is shown. As shown in FIG. 5, the spinous processes are vertically divided by dividing the spinous process 21 of the cervical vertebra (the fourth cervical vertebra in the illustrated example) 20 in the longitudinal direction by a cutting line 22. The spinal canal enlargement is performed by opening the split spinous process 21a to the left and right (left and right in FIGS. 5 to 7). The present inventors have expanded the split spinous process 21a by a pair of split spinous processes 21a. It has been found that the protrusion 21a does not expand uniformly and the head side opens wider than the caudal side. FIG. 7 shows such a state. Reference numeral 23 denotes a vertebral body, and 24 denotes a spinal canal.
[0010]
The spinous process spacer 10 of the present invention has a trapezoidal shape with a narrow width on the side of the spinal canal 24 in the horizontal cross section (FIG. 6) when inserted between the open divided spinous processes 21a, and the divided spinous processes. Even in the forehead cross section in the vertical direction extending between 21a, it has a trapezoidal shape with a wide width on the head side. In other words, the spinous process spacer 10 of the present invention has a symmetrical trapezoid 11 when viewed from the plane and another symmetrical trapezoid 12 when viewed from the front. In addition, a rectangle 13 is formed when viewed from the side. The spinous process spacer 10 has a through hole 14 in a direction connecting the paired divided spinous processes 21a.
[0011]
The angles α and β at both ends from the long side to the short side of the trapezoid 11 in the horizontal cross section and the trapezoid 12 in the forehead cross section are both preferably 10 ° or more and less than 90 °, particularly 40 ° or more and 85 °. It is preferable to make it less than.
[0012]
As shown in FIGS. 6 and 7, the spinous process spacer 10 of the present invention has a narrow side facing the spinal canal 24 side in the horizontal section and a wide side facing the head side in the forehead section. The insertion is fixed between the divided spinous processes 21a. At this time, the fixing thread is passed between the pair of split spinous processes 21a and the through hole 14.
[0013]
FIG. 8 shows another embodiment of the present invention. In addition to the shape of the first embodiment, FIG. 8 is positioned radially outward of the spinal canal 24 in the horizontal section, that is, the divided spinous process 21a. This is an embodiment in which the flange 15 is provided integrally with the flange 15. According to this embodiment, the spinous process spacer 10 can be reliably prevented from falling into the spinal canal 24.
[0014]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, when performing cervical spinal canal expansion, the spinous process spacer with the very favorable adaptability to the space | interval of the vertically divided spinous process can be provided. When the spinous process spacer of the present invention is used, bone resorption after fixation does not occur, and adjacent spacers are arranged physiologically. It can be moved.
[Brief description of the drawings]
FIG. 1 is a perspective view of a spinous process spacer showing an embodiment of the present invention.
2 is a plan view of the spinous process spacer shown in FIG. 1. FIG.
3 is a front view of the spinous process spacer shown in FIG. 1. FIG.
4 is a side view of the spinous process spacer shown in FIG. 1. FIG.
FIG. 5 is a horizontal sectional view for explaining the spinous process longitudinal splitting of the cervical spine.
6 is a horizontal cross-sectional view showing a state in which the spinous process divided by the spinous process splitting method of FIG. 5 is opened and the spinous process spacer of the present invention is inserted therebetween. FIG.
FIG. 7 is a cross-sectional view of the forehead.
FIG. 8 is a perspective view showing another embodiment of a spinous process spacer according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Spinous process spacer 11 12 Trapezoid 13 Rectangular 14 Through-hole 15 Flange 20 Cervical vertebra 21 Spinous process 21a Split spinous process 22 Cutting line 23 Vertebral body 24 Spinal canal

Claims (2)

In the spinous process spacer that is inserted between the vertically divided spinous processes and expands the spinal canal, the horizontal section has a substantially trapezoidal shape with a narrow width on the spinal canal side, and the vertical direction across the divided spinous processes The forehead cross section has a substantially trapezoidal block shape with a wide width on the head side, and the cross section trapezoidal shape in the horizontal cross section and the forehead cross section is an angle of both ends from the long side to the short side, respectively. Is a spinous process spacer, characterized by being made of a biocompatible ceramic material.  The spinous process spacer according to claim 1, further comprising a flange positioned integrally with the outer side of the divided spinous process in a horizontal section.

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