JP5328051B2 - Intervertebral cage - Google Patents

Abstract

Disclosed is an intervertebral cage that is inserted diagonally from the posterior aspect of the body and as such can secure a normal lordosis. Said cage ensures shortened operating times and small scars and allows for surgery of reduced invasiveness that is easy on the patient. In the intervertebral cage that is inserted diagonally from the posterior side to replace damaged intervertebral discs of kyphotic lumbar vertebra and is left in place as such, the upper and lower surfaces of the main body are configured to have sloped surfaces such that the front end in the direction of insertion slopes down gradually to the back end according to the extent of the kyphosis while also forming ridges on the surfaces that extend in the transverse direction when inserted.

Description

  The present invention relates to an intervertebral cage that is inserted between vertebral bodies in place of a damaged intervertebral disc in the spine.

  When the disc is deformed or damaged due to disc herniation, spondylolisthesis, degenerative spondylosis, spondylosis, etc., the interval between the adjacent vertebral bodies is shortened, and the nerve roots that have come out of the vertebral body are compressed to this nerve root. Causes neurological disorders such as pain, numbness, or paralysis at the affected site. In such a case, an operation is performed in which all or part of the damaged intervertebral disc is removed and an artificial intervertebral disc (called an intervertebral cage) made of resin, metal, ceramics, carbon, artificial bone, or the like is inserted. By replacing the intervertebral disc with an intervertebral cage, the spacing between the vertebral bodies returns to normal, and at the same time, the normal lordosis or kyphosis of the spine is reconstructed (this is called Lordosis), and neuropathy is improved. This is because that.

  There are various types of intervertebral cages, and examples thereof include those disclosed in Patent Documents 1 and 2 below. In Patent Document 1, the thickness at the distal end on the insertion side is thicker than the thickness at the rear end (which gradually decreases toward the rear end), and independent protrusions such as spikes are formed on the upper and lower surfaces. It is provided. On the other hand, what is shown in Patent Document 2 is the same in that the upper surface and the lower surface are gradually lowered toward the rear, but instead of forming protrusions on the upper surface and the lower surface, a protrusion is formed, and an intermediate portion on the insertion side is formed. Is formed in a convex round shape with a top.

  However, what is common to both is that after inserting the intervertebral cage, it is rotated and directed back and forth. As is well known, there is a vertebral hole through which nerves pass directly behind the spine, and the intervertebral cage cannot be inserted from this direction. Therefore, it is usually inserted obliquely from the rear, but this requires skill to rotate and may damage the upper and lower vertebral bodies adjacent to each other during rotation. In addition, the operation time becomes long, and it takes time to heal, and the scars become large, which is contrary to the recently screamed minimally invasive surgery. On the other hand, if the indwelling state is left in place, the inclined surface that gradually decreases at the rear end is inclined obliquely, and a gap is formed between the vertebral body in part, and Lordosis cannot be secured.

JP 2002-095685 A JP 2004-073547 A

  In the present invention, the shape of the intervertebral cage is devised in a three-dimensional manner so that it can be placed while inserted, that is, normal Lordosis can be ensured without rotation or adjustment.

Under the above-described problems, the present invention is a substantially rectangular parallelepiped shape that is inserted obliquely from the rear and is placed in that state in place of the damaged intervertebral disc of the lumbar vertebra that is backed, as described in claim 1. In the intervertebral cage, the upper and lower surfaces of the body portion of the intervertebral cage are made to be inclined surfaces that are gradually lower in the horizontal direction of the body than the distal end side in the insertion direction on the upper and lower surfaces of the body portion of the intervertebral cage. together, the main body portion on the upper and lower surfaces intersect at an angle to the insertion direction line which coincides with the longitudinal axis, of the same height which Konobe in the lateral direction in the front-rear direction line at right angles with the body ridges to the tip side The present invention provides an intervertebral cage characterized in that a plurality of rear end side ones are formed lower than one.

Further, according to the present invention, in the intervertebral cage described above, the means described in claim 2 in which the upper surface and the lower surface are made symmetrical with respect to the center plane, and the width of the rear end in the insertion direction described in claim 3 is set to the distal side. 5. Means that are tapered with respect to the width of the body, and means according to claim 4, wherein the body part is formed with a longitudinally extending long hole penetrating vertically, and a side part is formed with a hole facing the elongated hole. 5 described, which during the ridges are formed on the concave surface, the concave surface of the slope as well as provide a means which is steeper than towards towards the distal end side of the rear end, to claim 1-5 In the means, the injured intervertebral disc is of the thoracic vertebrae, and the upper and lower surfaces of the main body are gradually lowered in the horizontal direction of the body in the insertion direction from the front end side to the rear end side according to the degree of the frontal disc Same as the inclined surface that extends in the left-right direction when inserted into the upper and lower surfaces Provided is a means in which a plurality of protrusions having a height are made lower at the rear end than at the front end .

  According to the invention of claim 1, even if the intervertebral cage is left in the inserted state, the main body portion is in a form conforming to the state of the kyphosis and comes into full contact with the normal cage. Can secure the Lordosis. In this respect, it enables minimally invasive surgery that reduces the burden on the patient. Moreover, the protrusion which prevents a shift | offset | difference also turns to the left-right direction, and the suppression effect with respect to the load to the front-back direction (especially back) is high, and the necessity for reoperation etc. is reduced.

  According to the means of claim 2, more normal Lordosis can be ensured and the manufacture is facilitated, and according to the means of claim 3, insertion between vertebral bodies is facilitated. According to the means of claim 4, the growth of bone in the intervertebral cage is promoted, and according to the means of claim 5, since it is reared, it has a deterrent effect against a large rearward load. It will be expensive. According to the means of the sixth aspect, it is possible to deal with the thoracic vertebra which is prepared.

1 is a perspective view of an intervertebral cage according to the present invention. FIG. It is a top view of the intervertebral cage which concerns on this invention. It is a side view of the intervertebral cage according to the present invention. It is a rear view of the intervertebral cage according to the present invention. It is the slope view which looked at the intervertebral cage which concerns on this invention from diagonally backward. It is explanatory drawing of a lumbar spine. It is a top view of the state which inserted the intervertebral cage of this invention between the vertebral bodies. It is a side view of the state which inserted the intervertebral cage which concerns on this invention between vertebral bodies.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, taking the lumbar spine with the most cases as an example. First, the lumbar vertebra 1 is overlapped by the first to fifth vertebral bodies when the lumbar vertebra is explained with reference to the side view of the lumbar vertebra shown in FIG. 6 and the sectional plan view of FIG. (2 is a sacrum), and an intervertebral disc 3 exists between them. The vertebral body 1 is formed with a vertebral foramen (baudtail) 5 through which the nerve 4 passes, and a central spinous process 6 and two oblique lateral processes 7 are formed in the rear part of the vertebral hole 5. Yes. Further, a nerve root 8 protrudes from the vertebral foramen 5.

  1 is a perspective view of an intervertebral cage inserted into a lumbar spine according to the present invention, FIG. 2 is a plan view, FIG. 3 is a side view, FIG. 4 is a rear view, and FIG. As shown in the rear view, the intervertebral cage A has a substantially rectangular parallelepiped shape made of resin. A long hole 10 in the front-rear direction penetrating vertically is formed in the center of the main body portion 9, and a plurality of holes 11 facing the long hole 10 are formed in the side surface portion. In this case, the tip is spindle-shaped and the tail is tapered, and the whole is generally bullet-shaped. In addition, a vertical dovetail groove 12 is formed on the rear surface to which the surgical instrument for insertion is linked.

  Furthermore, the upper surface 13 and the lower surface 14 of the main body 9 are formed in a curved shape that is generally gently convex outward, and each surface has a plurality of surfaces extending obliquely with respect to the longitudinal axis. The ridge 15 is formed. This intervertebral cage A is inserted in place of the injured disc 3 of the lumbar vertebra, but the insertion direction is inserted obliquely from 40 to 45 ° with respect to the anteroposterior line and remains in that state. It is to be detained. Since the lumbar vertebra is reared, the intervertebral cage A in place of the intervertebral disc 3 is thicker at the front and thinner at the rear.

  Looking at the state in which the intervertebral cage A is inserted, in FIGS. 2 and 7, the front side (a) and (b) and the rear end corners (c) and (d) are shown. Take one point. In this case, (a) and (b) are in the same position in the front-rear direction, and (c) and (d) are forward in (c) and backward in (d). Accordingly, (a) and (b) are the same thickness, and (c) is thicker than (d). In addition, both the upper surface 13 and the lower surface 14 are inclined surfaces whose rear end side is gradually lowered with respect to the front end side. Even in this case, the difference between (b) and (d) rather than the step difference between (a) and (c). The step is made larger.

  In addition, the ridge 15 is formed in a direction extending in the direction of (a) to (b) (the left-right direction of the body). The concave surface 16 is formed between the ridges 15, but even in this case, the concave surface 16 has a steep slope toward the front side (a cliff immediately after the ridges 15). In this way, the difference in thickness between the front and the rear is to adapt to the radius of curvature of the lumbar vertebra that is reared, and to ensure Lordosis. Therefore, the thickness and the difference are different depending on which intervertebral disc 3 is replaced, and the upper surface 13 and the lower surface 14 may have a difference in thickness and curvature.

  Next, the replacement operation by the intervertebral cage A will be described. First, the skin at a position corresponding to the damaged intervertebral disc 3 is incised, and an instrument is inserted from approximately 40 to 45 ° obliquely backward of the body to pierce the intervertebral disc 2, and the damaged portion is removed. At this time, the insertion path of the intervertebral cage A is secured at the same time (in this case, since the intervertebral disc 3 is damaged mainly in the central nucleus pulposus, the relatively normal surrounding annulus is left as it is). The removed bone is filled in the slot 10 of the intervertebral cage A.

  Then, the vertebral bodies 1 existing above and below the removed intervertebral disc 3 are fixed with a jig (not shown), and the intervertebral cage A is inserted from the secured insertion path. At this time, the angle at the rear of the diagonal is an approximate guideline, and is not limited to this, but attention should be paid to the matters described later. Note that the intervertebral cage A having a substantially bullet shape has an effect of facilitating the insertion.

  By the way, the reason for selecting the obliquely backward angle as the insertion direction is that there is no organ or the like behind, but from the back, there is a vertebral hole 5 through which the nerve 4 passes and insertion is impossible. Therefore, this direction is avoided and the angle is set as described above. However, this direction originally has an intervertebral foramen (not shown), and the amount of bone to be cut is small, and it is sufficiently separated from the vertebral foramen 5. Because. When the intervertebral cage A is inserted, the jig is removed, the skin is sutured, and the operation is completed.

  At this time, the inserted intervertebral cage A may remain in that state, and as a rule, it is not rotated or adjusted in position. Incidentally, in FIG. 7, the inserted intervertebral cage A appears to be narrow, but as described above, the annulus fibrosus around the intervertebral disc 3 often remains, so this level is sufficient. When the jig is removed, the ridges 15 formed on the upper surface 13 and the lower surface 14 bite into the vertebral body 1, respectively, and displacement is prevented (FIG. 8). If there is an intervertebral disc 3 remaining, this also contributes to prevention of displacement.

  In this case, if the protrusion 15 is extended to the left and right, it is possible to effectively prevent the rearward shift because of the back-and-forth direction, particularly the rearward movement. At this time, the above-described shape of the concave surface 16 has an effect of further improving the blocking force. From this point, the extending direction of the protrusion 15 and the insertion direction of the intervertebral cage A have a correlation. In terms of preventing deviation, the protrusion 14 may be an independent protrusion such as a spike. According to this, the shift to the left and right can also be prevented. After the operation, bone enters through the long hole 10 and the hole 11 and grows to be close to the original intervertebral disc 3.

  Incidentally, it goes without saying that the dimensions (a) to (d) of the intervertebral cage A and the differences thereof correspond to the intervertebral disc 3 to be replaced. In addition, the intervertebral gauge A is not limited to the lumbar vertebra, but may be a thoracic vertebra whose bending direction is anteversion contrary to the above. However, in the case of the thoracic vertebra, the dimensions (a) to (d) and the difference between them are opposite to the above. Furthermore, the material is not limited to resin, but may be metal, ceramics, carbon, or artificial bone as described above.

A Intervertebral cage 1 Vertebral body 2 Sacrum 3 Intervertebral disc 4 Nerve 5 Vertebral hole 6 Spinous process 7 Transverse process 8 Nerve root 9 Body part of intervertebral cage 10 Long hole 11 Hole 12 Dovetail 13 Upper surface 14 Lower surface 15 Projection 16 Concave surface

Claims (6)

In intervertebral cage has a rear lordosis inserted obliquely from the rear instead of the damaged disc of the lumbar spine in which to elongated substantially rectangular solid to be indwelled remain in that state, intervertebral according to rear彎程degree The upper and lower surfaces of the cage main body are inserted into the insertion direction in which the rear end side in the insertion direction is an inclined surface that is gradually lower in the horizontal direction of the body than the distal end side and coincides with the longitudinal axis of the main body on the upper and lower surfaces. It intersects obliquely with respect to the line, that forms a plurality to lower towards the ones on the rear end side than the front-rear direction line and the tip of the same height of protrusion of Konobe in the lateral direction at a right angle side of the body Intervertebral cage characterized by.   The intervertebral cage of claim 1, wherein the upper and lower surfaces are symmetrical with respect to the central plane.   The intervertebral cage according to claim 1 or 2, wherein the width on the rear end side in the insertion direction is made smaller than the width on the front end side.   The intervertebral cage according to any one of claims 1 to 3, wherein a long hole in the front-rear direction penetrating vertically is formed in the main body portion, and a hole facing the long hole is formed in the side surface portion.   The intervertebral cage according to any one of claims 1 to 4, wherein a space between the protrusions is formed as a concave surface, and the inclination of the concave surface is steeper on the distal end side than on the rear end side. Injured intervertebral discs of the thoracic vertebrae, with the upper and lower surfaces of the main body section inclined gradually in the horizontal direction of the body from the rear end side to the front end side in the insertion direction according to the degree of the frontal deformity In addition, a plurality of protrusions having the same height extending in the left-right direction when inserted into the upper and lower surfaces are formed by lowering the rear end side than the front end side. Either intervertebral cage.