JPWO2018181895A1 - Interspinous implant - Google Patents

Abstract

An object of the present invention is to provide an interspinous implant, which can be screwed and inserted more easily than before in implanting a percutaneously screwed implant into a body. The screw part 1 of the interspinous process implant 100 has a first screw part 4 and a second screw part 5 in order from the distal end side. The first screw portion 4 has an imaginary surface S1 connecting the apexes of the screw threads, and has a tapered conical shape depressed outward, and the second screw portion 5 has an imaginary surface connecting the apex of the screw threads. S2 is shaped like a truncated cone bulging outward.

Description

  The present invention relates to an implant that fits between spinous processes.

  Examples of this type of technology include those described in Patent Documents 1 and 2. The interspinous process spacer described in Patent Literature 1 has a substantially conical screw portion that is screwed between spinous processes, a spacer portion formed in the longitudinal direction of the screw portion, and is freely engageable or appropriately connected with a tool. The implant includes a member and a freely attachable head, and has a through-hole at an axis of the screw portion, the spacer portion, and the head.

  According to the above interspinous process spacer, by using the expanding force generated when the screw portion is screwed between the spinous processes, the space between the spinous processes is reasonably enlarged, and the spacer portion is fitted between the spinous processes. Can be. Thus, even under local anesthesia, the interspinous spacer can be percutaneously screwed into the body and inserted into the body, and can be placed between the spinous processes.

  The interspinous process implant described in Patent Literature 2 is an improved version of the interspinous spacer described in Patent Literature 1, and has the following configuration as a new configuration. A plurality of slits or grooves having a length of 1/3 or more of the entire length of the interspinous implant are formed in the axial direction of the interspinous implant. These slits or grooves are slits or grooves having a depth reaching a through hole passing through the axis. These slits or grooves are provided at substantially equal intervals of less than 180 ° about the axis.

  According to the interspinous process implant described in Patent Document 2, the entire interspinous process implant can have flexibility and elasticity, and insertion and installation of the interspinous process implant can be simplified. Also, excessive stress is prevented from being applied to the spinous processes in contact with the interspinous implant. Thereby, the effect of the dilatation between the spinous processes can be maintained for a long time. In other words, bone destruction of the spinous process can be prevented.

Japanese Patent No. 4797174 Japanese Patent No. 5272279

  However, the interspinous process spacer described in Patent Literature 1 and the interspinous implant described in Patent Literature 2 in which the interspinous process implant has been improved still have problems to be further improved.

  The entire screw portion of the conventional implants (interspinous process spacer, interspinous process implant) described in Patent Documents 1 and 2 has a generally conical shape with a bulging partway. In this configuration, the diameter of the screw increases rapidly at the initial stage of percutaneously screwing the implant into the body, and the implant receives great resistance at the stage where the screw does not bite into the tissue in the body. Would.

  Just below the skin is a tough fascia made of collagen fibers. This fascia is a major cause of the above-mentioned resistance. In the procedures using the conventional implants described in Patent Literatures 1 and 2, it is necessary to perform a fasciotomy in addition to the skin incision in order to smoothly insert the implant into the body at an early stage.

  In addition, between the spinous processes, there is a thick interspinous ligament mainly composed of collagen fibers, which connects adjacent upper and lower spinous processes. In the procedures using the conventional implants described in Patent Documents 1 and 2, in order to smoothly insert the screw portion between the spinous processes, it is necessary to previously make a hole as a passage in the interspinous ligament. .

  The present invention has been made in view of the above circumstances, and has as its object the purpose of inserting a percutaneous screw into a body percutaneously and inserting the implant into the body more easily than before. It is to provide an inter-projection implant.

  The present invention provides a barb having a substantially conical screw portion having a screw-shaped outer peripheral surface, a head coaxial with the screw portion, and a spacer portion formed between the screw portion and the head. An interspinous implant that fits between the processes. The screw part has a first screw part and a second screw part in order from the tip side. The first screw portion has an imaginary surface connecting the vertices of the screw thread, and has a tapered conical shape depressed outward, and the second screw portion has an imaginary surface connecting the apex of the screw thread. It is shaped like a truncated cone bulging outward.

  According to the present invention, the constituent elements of the present invention, in particular, the virtual surface connecting the apexes of the threads of the first screw portion on the tip side of the screw portion is formed into a tapered conical shape that is concave outward. As a result, the diameter of the screw of the first screw portion gradually increases from the tip of the screw portion toward the spacer portion. This makes it easier for the screw portion to bite into the body tissue along the screw thread without receiving a large resistance.

  That is, according to the interspinous process implant of the present invention, when the implant is percutaneously screwed into the body and inserted, the screw can be inserted more easily than before.

1 is a perspective view of an interspinous implant according to an embodiment of the present invention. FIG. 2 is a side view of the interspinous implant shown in FIG. 1. It is AA sectional drawing of FIG. It is a figure for explaining composition of a screw of a screw part. It is a photograph under X-ray fluoroscopy in the state where the guide pin is being inserted between the spinous processes of the pig (the back of the pig is photographed from the side). It is a photograph under X-ray fluoroscopy in a state where an interspinous process implant is being inserted toward a spinous process of a pig (the back of the pig is photographed from the front). It is a photograph under X-ray fluoroscopy in a state where fitting of the interspinous process implant between the spinous processes of the pig is completed (the back of the pig is photographed from the front). It is a photograph under X-ray fluoroscopy in a state where fitting of the interspinous process implant between the spinous processes of the pig is completed (the back of the pig is photographed from the side). It is a CT image of a pig three months after inserting the interspinous process implant between spinous processes. FIG. 6 is a side view of an interspinous implant according to another embodiment of the present invention. It is BB sectional drawing of FIG. It is a photograph in the state where the implant which is an Example of the interspinous process implant shown in FIGS. 10 and 11 was filled with the crushed bone (artificial bone) in the state containing water.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

(Configuration of the interspinous implant)
The configuration of the interspinous implant 100 according to one embodiment of the present invention will be described with reference to FIGS. The interspinous implant 100 is an implant that is fitted between the spinous processes, and has an overall shape of a spindle. This interspinous process implant 100 includes an implant body 6, a front insert 7 (metal member) attached to a distal end of the implant body 6, and a rear insert 8 (metal member) attached to a rear end of the implant body 6. And are the main components. The implant main body 6 of the present embodiment is formed of PEEK resin (polyetheretherketone resin). Examples of the material of the implant body 6 other than the PEEK resin include a metal material such as titanium, a titanium alloy, and stainless steel, and a ceramic. Further, a resin (medical plastic) other than the PEEK resin may be used as the material of the implant body 6. Examples of applicable resins other than PEEK resin include polyvinyl chloride (PVC) resin, polypropylene (PP) resin, polyethylene (PE) resin, polycarbonate (PC) resin, and the like. Further, the front insert 7 and the rear insert 8 of the present embodiment are formed of a titanium alloy. Materials of the front insert 7 and the rear insert 8 other than the titanium alloy include metal materials such as tantalum and stainless steel, and ceramics.

  The overall length of the interspinous implant 100 is, for example, but not limited to, 30 mm to 40 mm.

  Here, each part of the interspinous process implant 100 in which the front insert 7 and the rear insert 8 are attached to the implant body 6 has a substantially conical (conical) screw portion 1 having a screw-shaped outer peripheral surface, and a screw portion. 1 and a spacer portion 3 formed between the screw portion 1 and the head portion 2.

<Screw part>
As shown in FIG. 2 and the like, the screw portion 1 is a tapered screw as a whole, and has a first screw portion 4 and a second screw portion 5 in order from the distal end side. Here, in the first screw portion 4, the virtual surface S1 connecting the apexes of the screw threads has a tapered conical shape that is concave outward. On the other hand, in the second screw portion 5, the virtual surface S2 connecting the apexes of the screw threads is formed in a truncated cone shape bulging outward. In FIG. 2, the curves indicating the virtual surfaces S <b> 1 and S <b> 2 are shown slightly away from the screw portion 1 in consideration of the legibility of the drawing. Symbol P indicates an inflection point. Assuming that the axial length of the screw portion 1 is L, the inflection point P is located at about 0.3 L from the tip of the screw portion 1, but the position of the inflection point P is not limited thereto.

  The detailed configuration of the screw of the screw unit 1 will be described with reference to FIGS. In FIG. 4, reference numeral 30 denotes a material of the implant body 6 before the thread groove 13 (see FIG. 2) is formed. The thread groove 13 of the screw portion 1 of the present embodiment is formed by using two different types of ball end mills. One is a ball end mill having a tip ball portion 31 having a diameter of φ6, and the other is a ball end mill having a tip ball portion 32 having a diameter of φ2. FIG. 4 shows a cutting locus 33 of the spherical portion 31 of the φ6 ball end mill and a cutting locus 34 of the spherical portion 32 of the φ2 ball end mill. The thread groove processing by the φ6 ball end mill is spirally formed from a fitting concave portion 14 described later provided in the spacer portion 3 toward the front end side of the material 30. The thread groove processing by the φ2 ball end mill is performed in a spiral shape from the middle part between the fitting concave portion 14 and the tip of the material 30 toward the tip of the material 30. Prior to the thread groove machining by the φ2 ball end mill, the thread groove machining by the φ6 ball end mill is performed. That is, after the thread groove machining by the φ6 ball end mill, the thread groove machining by the φ2 ball end mill is performed.

  Here, the above-mentioned thread groove processing by the φ6 ball end mill and the φ2 ball end mill is performed from two points which are 180 degrees out of phase with each other in the circumferential direction of the material 30. That is, the screw portion 1 (the first screw portion 4 and the second screw portion 5) is a double thread.

  Due to the thread groove processing by the φ6 ball end mill, the bottom surface of the screw groove 13 adjacent to the spacer portion 3 of the second screw portion 5 becomes a curved surface of R3 (radius 3 mm, the same applies hereinafter). The outer edge of the spinous process (a part of the spinous process) can pass through. The top of the thread on the spacer 3 side of the second screw 5 is a curved surface that is not sharp in the implant axial direction. The radius of the bottom surface of the thread groove 13 adjacent to the spacer portion 3 of the second screw portion 5 is, for example, twice or more and four times or less the radius of the bottom surface of the thread groove 13 of the first screw portion 4. . It is preferable that the radius of the bottom surface of the screw groove 13 adjacent to the spacer portion 3 of the second screw portion 5 be R3 or more so that the outer edge of the spinous process (a part of the spinous process) enters the groove. .

  By the thread groove processing by the φ2 ball end mill, the bottom surface of the screw groove 13 becomes a curved surface of R1 (radius 1 mm, the same applies hereinafter) from the middle part of the second screw part 5, and the width of the screw groove 13 becomes narrow. Further, the top of the thread of the first screw portion 4 is sharp as shown in FIG. The radius of the bottom surface of the thread groove 13 of the first screw part 4 (including the thread groove of R1 of the second screw part 5) is not limited to R1.

  Here, the screw pitch of the screw portion 1 is set to 1.8 mm, 1.4 mm, 2.1 mm, and 2.3 mm every half rotation from the tip end side toward the fitting concave portion 14 (spacer portion 3). As described above, the screw pitch of the screw portion 1 is a variable pitch in which the pitch decreases in the first screw portion 4 and then increases in the second screw portion 5 from the distal end side toward the spacer portion 3. It has been.

  First, by setting the screw pitch of the second screw portion 5 to be a variable pitch in which the pitch increases from the front end side to the spacer portion 3, an imaginary surface connecting the vertices of the screw thread at the front end side of the screw portion 1. When S1 is a tapered conical shape depressed outward, and a virtual surface S2 connecting the apexes of the screw threads on the spacer portion 3 side of the screw portion 1 is a frustoconical shape bulging outward, The thread groove 13 of the 2 screw portion 5 and a fitting recess 14 described later provided in the spacer portion 3 can be connected (smoothly) without a large step. As a result, the fitting recess 14 of the spacer 3 is easily guided to the outer edge of the spinous process.

  In addition to increasing the screw pitch of the second screw portion 5 from the distal end toward the spacer portion 3, the first screw portion 4 reverses the screw pitch from the distal end toward the spacer portion 3. When the virtual surface S1 is formed into a tapered conical shape that is concave outward and the virtual surface S2 is formed into a truncated conical shape that expands outward, the screw groove of the first screw portion 4 13 and the screw groove 13 of the second screw portion 5 can be easily (smoothly) connected without a large step. When the screw grooves 13 of the first and second screw portions are connected without a large step (smoothly), the screw grooves 13 of the second screw portion 5 are easily guided to the outer edge of the spinous process.

  The numerical value of the screw pitch is not limited to the above. Regarding the variable pitch, the first screw portion 4 has a constant screw pitch, for example, and the second screw portion 5 has a variable screw pitch in which the pitch increases from the distal end toward the spacer portion 3. May be. Even with such a variable pitch, the imaginary surface S1 connecting the apexes of the threads on the tip side of the screw portion 1 is formed into a tapered conical shape that is recessed outward, and the threads on the spacer portion 3 side of the screw portion 1 are formed. When the imaginary surface S2 connecting the vertices is formed in a truncated cone shape bulging outward, the screw groove 13 of the first screw portion 4 and the screw groove 13 of the second screw portion 5 are formed without a large step (smoothly). ) Can be connected.

  Here, in the present embodiment, the thread groove 13 of the first screw part 4 and the thread groove 13 of the second screw part 5 are smoothly connected. Further, a thread groove 13 of the second screw portion 5 and a fitting concave portion 14 provided in the spacer portion 3 described later are also smoothly connected. Since the screw groove 13 of the first screw portion 4 and the screw groove 13 of the second screw portion 5 are smoothly connected, the screw groove 13 of the second screw portion 5 can be easily guided to the outer edge of the spinous process. Become. In addition, since the screw groove 13 of the second screw portion 5 and the fitting recess 14 described later provided in the spacer portion 3 are smoothly connected, the fitting of the spacer portion 3 to the outer edge of the spinous process is possible. The recess 14 is easily guided. Note that “smooth connection” mathematically refers to a surface in which the tangent plane of a point (X0, Y0, Z0) on a curved surface is uniquely determined regardless of the direction. "The tangent plane is uniquely determined irrespective of the direction" means that the point on the curved surface is (X0, Y0, Z), and the tangent plane obtained by setting the Z coordinate as Z → Z0 is the point on the curved surface as (X0 , Y, Z0), a tangent plane obtained by determining the Y coordinate as Y → Y0, a point on the curved surface as (X, Y0, Z0) and an X coordinate obtained as X → X0 are uniquely determined. That means. The term “smoothly connected” in the present invention is not limited to the strict meaning as described above. The tangent plane need not be completely uniquely determined, and the coefficient of the equation of the tangent plane may have an error of about 6% (preferably, an error of about 3%).

  As shown in FIG. 3, the virtual surface T connecting the bottom points of the screw grooves of the second screw portion 5 has a substantially truncated cone shape (a truncated cone shape bulging outward). Thus, the implant can be screwed in between the spinous processes while gradually widening the space between the spinous processes on the bottom surface of the thread of the second screw portion 5 or the like.

  On the other hand, a hole 6a in which the front insert 7 is embedded and a hole 6b having a larger diameter than the hole 6a are provided in the axial center of the implant body 6 in order from the distal end side. The front insert 7 is a metal member attached to the distal end of the first screw portion 4 and has a cylindrical shape. The outer diameter of the front insert 7 is, for example, about 2.5 mm. The front end 7a of the front insert 7 is sharpened by various processes.

<Spacer part>
The spacer portion 3 is a portion that fits between the spinous processes. As shown in FIG. 2, the spacer portion 3 has two fitting recesses 14 facing each other in a U shape in a side view (two fitting recesses 14 having a phase difference of 180 degrees around the axial direction). . The spinous process fits into the fitting recess 14. The fitting recess 14 has a curved surface of R6 in a side view. In FIG. 2, as shown by a curved arrow on the surface of the fitting recess 14, in a cross-sectional view orthogonal to the axial direction of the implant, the fitting recess 14 has both sides higher than the central portion. The curved surface has a low shape (a shape similar to a so-called saddle of a harness). In this manner, the U-shaped fitting concave portion 14 in a side view has a curved surface (shape similar to the saddle described above) in which both sides are lower than the central portion in a cross-sectional view orthogonal to the axial direction of the implant. Thereby, the screw groove 13 adjacent to the spacer portion 3 of the second screw portion 5 and the fitting concave portion 14 of the spacer portion 3 can be easily connected (smoothly) without a large step. Note that the radius of the bottom surface of the fitting recess 14 in a side view is not limited to R6.

  When the two fitting recesses 14 are provided to face each other, the spinous process can be easily fitted into the spacer portion 3. In addition, since the fitting concave portion 14 is formed in a U-shape in a side view, excessive stress is prevented from being applied to the spinous process in contact with the interspinous process implant 100.

  Here, in the screw groove 13 of the second screw portion 5, the depth of the groove of the portion 13a (see FIG. 2) connected to the fitting concave portion 14 is shallower than the depth of the groove of this portion (front of the screw tip side). It is preferred that By doing so, the load at the time of passing the spinous process is slightly increased, but the spinous process feels like going over the portion 13a, and prevents reverse rotation of the implant when the spinous process is fitted into the fitting recess 14. be able to.

  Further, on both sides of the fitting concave portion 14 in the axial direction of the implant, X-ray marker pins 9 as identification members that can be identified by X-ray fluoroscopy are embedded. The X-ray marker pins 9 of the present embodiment are formed of titanium. The material of the X-ray marker pin 9 other than titanium includes platinum, gold, cobalt, nickel, chromium, tantalum, stainless steel, and alloys thereof. Since these metals, including titanium, are metals that attenuate X-rays, the X-ray marker pins 9 can be identified by X-ray fluoroscopy.

  The X-ray marker pin 9 is buried on the side of the implant body 6 so that its longitudinal direction is directed to the axial center of the implant. A total of four X-ray marker pins 9 are embedded in the implant main body 6, one on each side of each of the two fitting recesses 14 facing each other.

<Head>
The head 2 is a portion to which a screwing torque is applied when the interspinous process implant 100 is screwed into the body and inserted. A rear insert 8 is embedded in the head 2. The rear insert 8 and the implant main body 6 are fixed with pins 11. As shown in FIG. 3, a circular hole 8a formed with a female screw and a hexagonal hole 8b are provided in the axial center of the rear insert 8 in this order from the distal end side. The hexagonal hole 8b is a hole into which a tool such as a screwdriver is inserted. Since the rear insert 8 is made of metal, it is possible to securely transmit the torque to the implant using the tool such as a screwdriver. Can be. Here, when the screw portion 1 is a right-handed screw, the female screw formed in the hole 8a is a left-handed screw. When the screw portion 1 is a left-handed screw, the female screw formed in the hole 8a is a right-handed screw. In this embodiment, since the screw portion 1 is a right-hand thread, the female screw formed in the hole 8a is a left-hand thread. The reason why the screw of the screw portion 1 and the female screw formed in the hole 8a are the screws that are twisted in opposite directions is that the interspinous process implant 100 is removed from the body when inserted into the body. This is because if the screw is rotated in the opposite direction, it can be easily removed.

  In addition, the interspinous implant 100 is provided with a through hole 10 penetrating the axis thereof. The through-hole 10 includes a hole 7b of the front insert 7, a hole 6b of the implant body 6, and holes 8a and 8b of the rear insert 8. This through hole 10 is a hole that is passed through a guide wire. By providing the through-hole 10 penetrating the axis, the interspinous implant 100 can be inserted toward the space between the spinous processes using a guide wire.

  Here, a guide wire is also used when removing the implant. The distal end of the hole 6b of the implant body 6 is formed as a conical inclined surface 6bf so that the hole 6b is tapered. The inclination angle α of the inclined surface 6bf with respect to the axial direction is preferably 45 degrees or less. By setting the inclination angle α to 45 degrees or less, it becomes easy to insert the guide wire into the through hole 10 of the implant when removing the implant placed between the spinous processes. The lower limit angle of the inclination angle α is, for example, 10 degrees.

  In addition, scar tissue may intervene in a cavity such as the hole 8a of the interspinous implant 100 placed between the spinous processes. Here, the rear end of the hole 8a of the present embodiment is a tapered conical inclined surface 8ar. By doing so, the tip of the driver can be easily screwed into the hole 8a when removing the implant, and the guide wire can be easily inserted into the implant.

  As shown in FIGS. 1 to 3, two slits 12 extending in the axial direction are provided on the side surface of the implant body 6. Two slits 12 are provided with a phase difference of 180 degrees around the axial direction. More specifically, two of them are provided with a phase difference of 90 degrees around the axial direction with respect to the fitting recess 14, avoiding the fitting recess 14 of the spacer portion 3.

  As shown in FIGS. 1 and 2, the slit 12 extends from a middle part of the second screw part 5 to a middle part of the head 2, and both ends are rounded to avoid stress concentration. In addition, as can be seen from FIG. 3, the slit 12 communicates with the hole 6b of the implant main body 6 that forms the through hole 10 that passes through the axis.

  The slit 12 imparts elasticity to the interspinous process implant 100, so that excessive stress is prevented from being applied to the spinous process in contact with the interspinous process implant 100.

(How to use the interspinous process implant)
A method for using the interspinous implant 100 will be described. The interspinous implant 100 has been developed mainly for performing minimally invasive treatment for lumbar spinal canal stenosis. Under local anesthesia, by inserting the interspinous process implant 100 between the spinous processes through a small skin incision, the spinal canal stenosis site is widened and the symptoms are expected to be improved.

  Here, the photographs shown in FIGS. 5 to 8 are obtained by taking an X-ray fluoroscopic moving image of the state when the test was performed on a pig and extracting the moving image. In the following description, a method of inserting (fitting) the interspinous process implant 100 between the spinous processes of the human body will be described with reference to FIGS.

  First, the surgeon makes an incision in the skin on the back of the human body, for example, by 20 to 25 mm, and inserts the guide wire 50 from the incised portion to between the spinous processes 60 under fluoroscopy with an X-ray monitor (see FIG. 5). . Here, the guidewire 50 is inserted until its tip exceeds the facet joint.

  Next, using the through hole 10 of the interspinous process implant 100, the interspinous process implant 100 is passed through the guide wire 50, and the interspinous process implant 100 is inserted into the body from the screw portion 1 side.

  As described above, immediately below the skin is the fascia made of tough collagen fibers. The operator inserts the driver 51 into the hexagonal hole 8b of the rear insert 8 at the rear end of the implant, and twists the tip of the first screw portion 4 into the body while applying a turning force to the driver 51. . Here, since the virtual surface S1 connecting the apexes of the screw threads of the first screw portion 4 has a tapered conical shape that is depressed outward, the first screw portion 4 extends from the tip toward the front (rearward). The diameter of the screw No. 4 gradually increases. For this reason, the tip of the screw portion 1 is not easily subjected to great resistance, and is likely to bite into tissue in the body along the screw thread. In fact, tests in pigs did not harm without incision of the fascia.

  In addition, since the first screw portion 4 is not a single-threaded screw but a double-threaded screw, the chance of digging into a tissue in the body is double as compared with the case of the single-threaded screw. Thus, the interspinous process implant 100 has a higher biteability into tissues in the body. In addition, the front insert 7 having a sharpened tip is embedded in the tip of the first screw portion 4, and the apex of the thread of the first screw portion 4 is sharpened as shown in FIG. By doing so, the interspinous process implant 100 has a higher biteability into tissues in the body.

  When the interspinous implant 100 is screwed into the body along the guide wire 50 while applying a rotating force to the driver 51, the X-ray marker pins 9 embedded on both sides of the two fitting recesses 14 of the spacer portion 3 are formed. Is observed on an X-ray monitor (see FIG. 6). Therefore, the surgeon can clearly grasp the position and posture of the interspinous process implant 100. The X-ray marker pin 9 is embedded in the side of the implant body 6 so that its longitudinal direction is directed to the center of the rotation axis of the implant, so that it can be easily understood that the X-ray marker pin 9 rotates.

  As the interspinous implant 100 is advanced, the tip of the implant reaches the interspinous ligament. In a procedure using a conventional implant, a hole as a passage of the implant was previously formed in the interspinous ligament using a tool. On the other hand, according to the interspinous process implant 100 of the present embodiment, since the biting property of the distal end portion of the screw portion 1 is greatly improved, a hole as a passage of the implant is formed in the interspinous ligament using a tool, The implant can be screwed between the spinous processes without prior opening.

  When the implant is screwed into the space between the spinous processes, the screw groove 13 of the first screw portion 4 and the screw groove 13 of the second screw portion 5 are smoothly connected to each other. The outer edge part (part) of the spinous process 60 can be smoothly transferred to the screw groove 13 of the second screw part 5.

  When the second half of the screw portion 1 reaches the vicinity of the spinous process 60, the screw groove 13 adjacent to the spacer portion 3 of the second screw portion 5 forms an outer edge portion (part) of the spinous process 60 in the screw groove 13. The implant is screwed between the spinous processes 60 while the outer edge of the spinous process 60 is fitted into the thread groove 13 because it is formed so as to pass through. This prevents the space between the spinous processes 60 from being excessively expanded. Further, since the spinous process 60 is screwed in such a manner as to sandwich the spinous process 60 with the screw groove 13, the spinous process 60 is supported on the inner wall surface of the screw groove 13. As a result, breakage of the spinous process 60 is prevented. In the second screw portion 5, since the diameter of the thread is gradually increased toward the spacer portion 3, even if the spinous process 60 comes off from the screw groove 13, damage to the spinous process 60 is suppressed. You.

  In addition, since the second screw portion 5 is formed as a double thread, there are screw grooves 13 that correspond to each other at a position having a phase difference of 180 degrees around the axial direction. Therefore, when screwing into the spinous processes 60, the two thread grooves of the implant serve as guides with respect to the spinous processes 60, so that the implants do not incline greatly obliquely from the insertion axis direction. The implant can be screwed in at an angle close to vertical).

  When the second screw portion 5 of the screw portion 1 exceeds the space between the spinous processes 60, the spinous process 60 fits into the fitting recess 14 of the spacer portion 3. When the implant is to be pushed further into the back, the spinous process 60 hits the implant head 2 without the thread groove 13 and the resistance felt by the operator's finger increases. The surgeon can confirm that the spinous process 60 has been fitted into the fitting concave portion 14 of the spacer portion 3 by the sensed resistance and the visual inspection of the X-ray marker pin 9. After that, the surgeon operates the driver 51 so that the direction connecting the adjacent spinous processes 60 and the direction connecting the opposite fitting recesses 14 of the spacer portion 3 coincide with each other, and The posture of the interspinous process implant 100 is finely adjusted while confirming it with the X-ray marker pin 9 so that the implant is substantially vertical. Completion of the fine adjustment completes fitting of the interspinous process implant 100 (see FIGS. 7 and 8). Note that the guide wire 50 is withdrawn from the body when the implant is inserted between the spinous processes 60 to some extent.

  Here, Table 1 shows a plurality of examples of the time required for the operation for fitting one interspinous process implant 100 of the present embodiment between the spinous processes 60 of the pig. As can be seen from Table 1, the time required for the treatment was 16 minutes at the longest, 6 minutes at the shortest, and about 10 minutes on average. Thus, the surgeon was able to fit the implant between the spinous processes 60 of the pig in a very short time. That is, according to the interspinous process implant 100 of the present embodiment, when the implant is percutaneously screwed into the body and inserted, the implant can be more easily screwed into the body and inserted.

  FIG. 9 is a CT image of a pig three months after the interspinous process implant 100 has been fitted between the spinous processes 60. FIG. 9A is a CT scan image of the back of the pig as viewed from the front, and FIG. 9B is a CT scan image of the back of the pig as viewed from the side. In the test using a pig, two interspinous implants 100 were fitted between different spinous processes 60, respectively.

  As can be seen from FIG. 9, at the stage three months after the fitting, the interspinous process implant 100 does not fall out between the spinous processes 60, and is firmly fitted between the spinous processes 60 in the same position and posture immediately after the operation. I was still in a state.

<Removal of interspinous implant>
The interspinous implant 100 is also devised so that it can be easily removed from the body. When removing the interspinous process implant 100, a rod-shaped member in which a male screw (left-handed screw) is formed only in the distal end portion of the hole 8a in which the female screw (left-handed screw) of the rear insert 8 is formed at the rear end of the implant. (Not shown, screwdriver). In this state, the interspinous process implant 100 is pulled out from the body while rotating the rod-shaped member counterclockwise. The interspinous implant 100 is pulled out from the body while rotating in the opposite direction to the direction during insertion into the body. Since the screw portion 1 is a right-handed screw, the interspinous process implant 100 is smoothly pulled out of the body. Since the outer edge of the spinous process 60 passes through the screw groove 13 adjacent to the spacer portion 3, the space between the spinous processes at the top of the screw thread of the screw portion 1 is prevented from being excessively expanded. That is, even at the time of removing the implant, breakage of the spinous process 60 is prevented.

(When the interspinous implant is used for intervertebral fixation)
An embodiment in which the interspinous process implant is used for intervertebral fixation will be described with reference to FIGS.

  The interspinous implant 100 has been developed mainly for performing minimally invasive treatment for lumbar spinal canal stenosis. Under local anesthesia, by inserting the interspinous process implant 100 between the spinous processes through a small skin incision, the spinal canal stenosis site is widened and the symptoms are expected to be improved. In contrast, the interspinous process implant 101 shown in FIGS. 10 and 11 is developed with the primary purpose of inducing bone fusion from the adjacent spinous process to the pedicle and performing intervertebral fixation in a minimally invasive manner. It was done.

  In FIGS. 10 and 11, the illustration of the screw shapes (threads, screw grooves) of the screw portion 1 (the first screw portion 4 and the second screw portion 5) of the implant is omitted. 10 and 11, the same reference numerals are given to the same components as the components of the interspinous process implant 100 shown in FIGS.

  In addition, it is of course possible to apply the various configurations and materials of each part of the interspinous implant 100 described above, and various modifications of the respective parts described above to the interspinous implant 101 described below.

  Hereinafter, the difference between the interspinous process implant 101 and the interspinous process implant 100 will be mainly described.

(Configuration of the interspinous implant)
Similarly to the interspinous implant 100, in the interspinous implant 101, the slit 15 extending in the axial direction and communicating with the through hole 10 (6b) is implanted from the head 2 through the spacer 3 to the screw 1. It is provided on the side of.

  The slit 15 is a slit for accommodating the crushed bone, and is wider than the slit 12 provided on the side surface of the interspinous process implant 100. The “crushed bone” is a transplanted bone (bone of a patient), an artificial bone, or the like.

  Further, as shown in FIG. 11, in the present embodiment, the outer shape of the cross section of the spacer portion 3 perpendicular to the axial direction is substantially triangular. In addition, it may be not only a substantially triangle but also a substantially polygon such as a substantially quadrangle and a substantially pentagon. A substantially polygon is not a polygon with sharp corners but a polygon with rounded corners (R-processed), with each side being a straight line or a curved line. . In addition, when each side is a curve, it is preferable that the curve be a curve bulging outward rather than a curve concaved outward.

  The slits 15 are provided on each side of the substantially triangular spacer portion 3, that is, a plurality of slits 15 are provided around the axial direction, and the widths W thereof are the same in the present embodiment. In addition, each width W does not necessarily need to be the same. In the present embodiment, three slits 15 are provided at equal intervals around the axial direction. In the case of the substantially triangular spacer portion 3, two or three slits 15 are preferably provided at equal intervals around the axial direction.

  Here, it is preferable that the width W of the slit 15 is 2 mm or more, or 4 mm or more, in order to store a sufficient amount of the crushed bone in the slit 15 and the through hole 10 (6b). . Further, in order to secure a certain strength of the spacer portion 3, the width W is preferably set to 10 mm or less or 8 mm or less.

  Further, it is preferable that the length of the slit 15 is equal to or longer than １ ／ of the entire length of the interspinous process implant 101. According to this, the fractured bone can be arranged in the width direction of the spinous process with respect to the mother bed for bone union described later.

  The broken bone may be stored in the slit 15 and the through-hole 10 (6b) as it is, however, in order to further prevent the broken bone from falling from the slit 15, water is contained. It is preferable to store the broken bone in the slit state in the slit 15 and the through hole 10 (6b).

  Here, FIG. 12 is a photograph of the interspinous process implant 102, which is an example of the interspinous process implant 101 shown in FIGS. 10 and 11, filled with artificial bone 70 containing water. When water is applied to the crushed bone, the crushed bone becomes a so-called sand dumpling. Therefore, as shown in FIG. 12, the artificial bones 70 (crushed bones) can be accommodated in the slits 15 in such a manner that a part thereof overflows from the slits 15 outward. When the artificial bone 70 (crushed bone) is accommodated in the slit 15 in such a manner that a part thereof overflows from the slit 15, when the interspinous process implant 102 is placed between the spinous processes, the mother bed to be described later is formed. The artificial bone 70 (crushed bone) can be more reliably brought into contact with the (cancellous bone portion from which cortical bone has been scraped off), and as a result, bone fusion can be further promoted.

(How to use the interspinous process implant)
A method of using the interspinous process implant 101 will be described. Since the method of using the interspinous process implant 101 of the present embodiment is similar to the method of using the interspinous process implant 100, a specific method of using the interspinous process implant 101 of the present embodiment will be mainly described. It shall be.

  The interspinous process implant 101 is an interspinous process implant suitable for inducing bone fusion from an adjacent spinous process to a pedicle and performing intervertebral fixation in a minimally invasive manner.

  First, the surgeon prepares the interspinous process implant 101 filled with the crushed bone for placement in the interspinous process as follows. The surgeon makes an incision in the skin on the back of the human body, for example, by 20 to 25 mm, and then creates a pilot hole between the spinous processes using a tool. Then, in the prepared hole, from the spinous process to the pedicle, the cortical bone of the spinous process and the lamina is scraped, and the trabecular bone is exposed to form a mother bed.

  Thereafter, the surgeon inserts the interspinous process implant 101 filled with the crushed bone into the above-mentioned mother bed portion between the spinous processes in the same manner as the method of using the interspinous process implant 100 and places the same. . The crushed bone is filled in advance in the slit 15 and the through-hole 10 (6b) of the interspinous process implant 101 as it is or in a state containing water. When using the crushed bone containing water, the blood is applied to the crushed bone using a patient's blood, physiological saline, or the like.

  When the interspinous implant 101 is placed between the spinous processes, the fractured bone filled in the slit 15 of the interspinous implant 101 eventually causes bone fusion from the adjacent spinous process to the pedicle. Since one of the sides of the substantially triangular spacer portion 3 faces the mother floor, a slit 15 is provided on each side of the spacer portion 3, and the slit 15 has a broken bone. Is filled, the contact between the crushed bone and the mother bed becomes more reliable, and the progress of bone fusion is further promoted.

  According to the interspinous process implant 101 of the present embodiment, bone fusion can be induced from the adjacent spinous process to the pedicle, and the intervertebral fixation can be performed in a minimally invasive manner. A longer-term stabilization of the intervertebral fixation as compared to conventional intervertebral fixation in which the vertebrae are hit and connected.

  Table 2 shows a plurality of examples of the time required for the operation of inserting one interspinous process implant 102 shown in FIG. 12 filled with the artificial bone 70 in a state containing water between the spinous processes of a pig. As can be seen from Table 2, the time required for the treatment was 12 minutes at the longest, 4 minutes at the shortest, and 7 minutes on average. In this way, the operator was able to fit the implant between the spinous processes of the pig in a very short time. That is, according to the interspinous process implant 101 of the present embodiment, when the implant is percutaneously screwed into the body and inserted into the body, even if the broken bone is filled in the implant, the implant can be used. It can be easily screwed into the body and inserted.

(Modification)
When the implant main body 6 is formed of a metal material such as a titanium alloy or ceramic, the front insert 7 and the rear insert 8 are not formed as separate components from the implant main body 6, and the implant main body 6, the front insert 7, and the rear insert 8 are It may be formed integrally with a metal material such as a titanium alloy.

  Further, when the implant body 6 is formed of PEEK resin as in the above-described embodiment, at least one of the front insert 7 and the rear insert 8 is formed integrally with the implant body 6 from PEEK resin. You may.

  The outer shape of the cross section orthogonal to the implant axial direction of the spacer portion 3 which is a portion fitted between the spinous processes is similar to the spacer portion of the interspinous implant described in Patent Document 2 (Japanese Patent No. 5272279). , A circle, an ellipse, and the like.

  The embodiment of the present invention and its modifications have been described above. In addition, various changes can be made within a range that can be assumed by those skilled in the art.

1: screw part 2: head part 3: spacer part 4: first screw part 5: second screw part 7: front insert (metal member)
8a: hole (through hole provided in the axis of the head)
9: X-ray marker pin (identification member)
10: Through-holes 12, 15: Slit 13: Screw groove 14: Fitting recess S1, S2: Virtual surface T: Virtual surface 100, 101: Interspinous implant

Claims (18)

A substantially conical screw portion having a screw-shaped outer peripheral surface,
A head coaxial with the screw portion,
A spacer portion formed between the screw portion and the head portion,
An interspinous implant fitted between the spinous processes, comprising:
The screw portion,
In order from the tip side, has a first screw portion and a second screw portion,
The first screw portion has an imaginary surface connecting the apexes of the screw threads, and has a tapered conical shape that is concave outward.
The interspinous process implant, wherein the second screw portion has an imaginary surface connecting the apexes of the screw threads and has a truncated conical shape bulging outward. The interspinous implant according to claim 1,
An interspinous implant, wherein a thread groove of the second screw portion adjacent to the spacer portion is formed so as to allow an outer edge of a spinous process to pass through the thread groove. The interspinous implant according to claim 1 or 2,
The interspinous implant, wherein the first screw portion and the second screw portion are double-threaded. The interspinous implant according to any one of claims 1 to 3,
The interspinous implant, wherein the screw pitch of the second screw portion is a variable pitch that increases in pitch from the distal end side to the spacer portion. The interspinous process implant according to claim 4,
The interspinous implant, wherein the screw pitch of the screw portion is a variable pitch that decreases in the first screw portion from the distal end side to the spacer portion. The interspinous implant according to any one of claims 1 to 5,
An interspinous implant, wherein an imaginary plane connecting the bottom points of the thread grooves of the second screw portion is substantially frustoconical. The interspinous implant according to any one of claims 1 to 6,
The interspinous implant, wherein the spacer portion has two opposing fitting concave portions having a U-shape in a side view. The interspinous process implant according to claim 7,
A spinous process in which the screw groove of the first screw portion and the screw groove of the second screw portion are smoothly connected, and the screw groove of the second screw portion and the fitting recess are smoothly connected; Between implants. The interspinous implant according to claim 7 or 8,
An interspinous implant, wherein identification members that can be identified by fluoroscopy are provided on both sides of the fitting recess in the axial direction. The interspinous implant according to any one of claims 1 to 9,
An interspinous implant, wherein a through hole passing through the axis is provided in the interspinous implant. The interspinous implant according to any one of claims 1 to 10,
An interspinous implant wherein an axially extending slit is provided on a side surface. The interspinous implant according to any one of claims 1 to 11,
A female screw is formed in a through hole provided in the axis of the head,
The interspinous implant, wherein the female screw is left-handed when the screw part is right-handed, and the female screw is right-handed when the screw part is left-handed. The interspinous implant according to any one of claims 1 to 12,
An interspinous implant, wherein the apex of the thread of the first screw portion is sharp. The interspinous implant according to any one of claims 1 to 13,
An interspinous implant, wherein a metal member having a sharp tip is attached to a tip of the first screw portion. The interspinous implant according to any one of claims 1 to 6,
A through-hole passing through the axis is provided in the interspinous process implant,
An interspinous implant, wherein a slit extending in the axial direction and communicating with the through-hole is provided on a side surface from the head to the screw via the spacer, for accommodating broken bone. The interspinous implant according to claim 15,
The interspinous implant, wherein the width of the slit is 2 mm or more and 10 mm or less. An interspinous implant according to claim 15 or 16,
The interspinous implant, wherein the length of the slit is at least 1/3 of the total length of the interspinous implant. The interspinous implant according to any one of claims 15 to 17,
The outer shape of the cross section orthogonal to the axial direction of the spacer portion is substantially polygonal,
An interspinous implant, wherein the slit is provided on each side of the substantially polygonal spacer portion.