Interspinous spacer

Abstract

To provide an interspinous process spacer that is excellent in minimal invasiveness and can more effectively widen the space between spinous processes. [Solution] An interspinous spacer (1) comprising a first engagement member (5), a second engagement member (7), a bolt member arranged between the first engagement member (5) and the second engagement member (7), a first expansion member (2), and a second expansion member (3); the first expansion member (2) and the second expansion member (3) are configured to be movable toward each other or away from each other along the longitudinal direction of the bolt member by rotation of the bolt member; and as the first expansion member (2) and the second expansion member (3) move relative to each other, they are configured to slide from a first state in which the first engagement member (5) and the second engagement member (7) are abutting each other to a second state in which they are apart from each other, and from the second state to the first state; in the first state in which they are abutting each other, the tip of the interspinous spacer forms a generally conical screw portion with a screw thread that can be screwed into between the spinous processes.

Description

[Technical Field]

[0001] The present invention relates to an interspinous spacer. [Background technology]

[0002] Interspinous spacers have been developed as minimally invasive implants for the purpose of widening the space between the spinous processes (Patent Document 1). These interspinous spacers include a substantially conical screw portion that screws into the space between the spinous processes, a spacer portion formed in the longitudinal direction of the screw portion, and a head portion that can be engaged with an appropriate tool or to which an appropriate connecting member can be attached, with through-holes formed in the axes of the screw portion, spacer portion, and head portion, and the outer contour of the overall shape being elliptical.

[0003] A method for percutaneously widening the interspinous space using this interspinous spacer is described below. First, the location of the narrowed spinal canal is confirmed using fluoroscopy techniques such as X-rays. Next, a guide member is introduced to the narrowed location through the skin of the patient's back from the posterolateral side. The guide member is then inserted into the through-hole of the interspinous spacer, and the screw portion of the interspinous spacer is rotated and inserted using a tool such as a screwdriver. The space between the spinous processes is widened by rotating and inserting the screw portion, and then the screw portion is passed through, sandwiching the spacer portion between the spinous processes to fix the space between the spinous processes. Finally, the guide member and tool are removed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4797174 Summary of the Invention [Problem to be solved by the invention]

[0005] While the above-described interspinous process spacer is certainly excellent in terms of minimal invasiveness, there is a limit to how much it can widen the space between the spinous processes, and there is still room for improvement. The present invention has been made to solve these problems, and it is an object of the present invention to provide an interspinous process spacer that is excellent in terms of minimal invasiveness and can widen the space between the spinous processes more effectively. [Means for solving the problem]

[0006] The above object of the present invention is to provide an interspinous spacer to be placed between adjacent spinous processes, the interspinous spacer comprising a first engagement member, a second engagement member, a bolt member placed between the first engagement member and the second engagement member, a first expansion member, and a second expansion member, wherein the first expansion member is threadedly engaged with the distal end side of the bolt member, and the second expansion member is configured to be able to support the bolt member so as to be freely rotatable on the bolt head side, and the first expansion member and the second expansion member are configured to be movable toward each other along the longitudinal direction of the bolt member by rotation of the bolt member in a first direction, and to be movable away from each other along the longitudinal direction of the bolt member by rotation of the bolt member in a second direction, and the first expansion member and the second expansion member are configured to be movable toward each other in the direction By moving, the first engagement member and the second engagement member are configured to be able to slide from a first state in which they abut each other in a direction away from each other along a vertical direction perpendicular to the longitudinal direction of the bolt member, and by moving the first expansion member and the second expansion member in a direction in which they move away from each other, the first engagement member and the second engagement member are configured to be able to slide from a second state in which they are spaced apart toward the first state, and this is achieved by an interspinous process spacer characterized in that in the first state, the tip portion of the first engagement member on the tip side of the bolt member, the tip portion of the second engagement member on the tip side of the bolt member, and a portion of the first expansion member together form an approximately conical screw portion with a screw thread that can be screwed between the spinous processes.

[0007] In the first state, the overall shape of the interspinous spacer is bullet-shaped, having a spacer tip side where the screw portion is formed and a spacer base side opposite the tip side, and the first expansion member has a screw tip portion that forms the tip portion of the screw portion, and a bolt connection portion that is connected to the screw tip portion and extends toward the spacer base side and has a female thread portion into which the bolt member can be screwed, and the spacer base side of the screw tip portion is formed with a first inclined surface along which the first engagement member can slide diagonally relative to the first expansion member, and a second inclined surface that is inclined opposite to the first inclined surface and along which the second engagement member can slide diagonally, and the second expansion member is preferably arranged on the spacer base side and is formed with a wedge-shaped portion that has a third inclined surface along which the first engagement member can slide diagonally and a fourth inclined surface that is inclined opposite to the third inclined surface and along which the second engagement member can slide diagonally, and a through hole formed in the wedge-shaped portion through which the bolt member is inserted.

[0008] In a spacer intermediate portion between the spacer distal end side and the spacer proximal end side, the first engaging member and the second engaging member are preferably each formed with a recess for receiving a surface of a spinous process.

[0009] It is preferable that the recess depth of the recess formed in the first engaging member and the recess depth of the recess formed in the second engaging member are different from each other.

[0010] At the base end side of the spacer, it is preferable that the first engaging member has a semi-ring-shaped first stopper portion protruding outward from its surface, and the second engaging member has a semi-ring-shaped second stopper portion protruding outward from its surface.

[0011] In the first state, it is preferable that the first stopper portion and the second stopper portion are integrated with each other to form a ring shape.

[0012] The bolt member further includes a guide member having a longitudinal direction perpendicular to the longitudinal direction of the bolt member, the guide member connecting the first engaging member and the second engaging member, It is preferable that the first engaging member and the second engaging member are configured to be movable between the first state and the second state with the guide member interposed therebetween.

[0013] The bolt member has a bolt head and a shaft body, and the shaft body is a half-threaded bolt member having a male-threaded shank portion on which a male thread is formed and a cylindrical shank portion on the bolt head side where no male thread portion is formed, and the cylindrical shank portion has a pair of ring-shaped expanded diameter portions that protrude radially outward from the shank portion and are arranged at a predetermined interval along the axial direction of the cylindrical shank portion, and the second expansion member has a through hole formed therein whose penetrating direction is a vertical direction perpendicular to the longitudinal direction of the half-threaded bolt member, and it is preferable that the bolt member further comprises a regulating pin that is inserted into the through hole and whose tip is arranged in the area between the pair of expanded diameter portions.

[0014] Of the pair of enlarged diameter portions, the enlarged diameter portion located on the bolt head side has a shank facing surface that faces the shank of the regulating pin, and the shank facing surface is formed with a pin receiving recess that can receive a portion of the shank surface of the regulating pin, and it is preferable that multiple pin receiving recesses are formed radially around the axis of the cylindrical shank on the shank facing surface.

[0015] The second expansion member preferably has an end face recess capable of accommodating the bolt head of the bolt member, and the opening edge of the end face recess is preferably formed in a rectangular or elliptical shape. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide an interspinous process spacer that is excellent in minimal invasiveness and can more effectively widen the space between spinous processes. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a side view showing a schematic configuration of an interspinous spacer according to the present invention. [Figure 2] 1 is a cross-sectional view showing a schematic configuration of an interspinous spacer according to the present invention. [Figure 3] 1 is a component diagram of an interspinous spacer according to the present invention. FIG. [Figure 4] 10 is an explanatory view showing a second state of the interspinous spacer according to the present invention. FIG. [Figure 5] 1(a) is a side view of the schematic configuration of the first expansion member, and FIG. 1(b) is a rear view of the schematic configuration as seen from the direction of the arrow A. FIG. [Figure 6] 5(a) is a plan view of the schematic configuration as seen from the direction of an arrow B in FIG. 5(a), and FIG. 5(b) is a rear view of the schematic configuration as seen from the direction of an arrow C in FIG. 5(a). [Figure 7] 7(a) is a schematic side view of the second expansion member, (b) is a schematic cross-sectional view thereof, and (c) is a schematic front view thereof as seen from the direction of arrow D in FIG. 7(a). [Figure 8] 7(a) is a plan view of the schematic configuration as seen from the direction of the arrow E in FIG. 7(a), (b) is a rear view of the schematic configuration as seen from the direction of the arrow F in FIG. 7(a), and (c) is a rear view of the schematic configuration as seen from the direction of the arrow G in FIG. 7(a). [Figure 9] FIG. 7(b) is a schematic cross-sectional view showing the HH cross section of FIG. 7(a). [Figure 10] FIG. 2 is a side view showing a schematic configuration of a bolt member. [Figure 11] FIG. 10 is an enlarged cross-sectional view of a main part of the second expansion member in a state where the restriction pins are fitted into the respective through holes. [Figure 12] 4 is a schematic diagram showing the end face of a second enlarged diameter portion of the bolt member. FIG. [Figure 13] FIG. 2(a) is a side view showing a schematic configuration of a first engagement member, and FIG. 2(b) is a plan view showing a schematic configuration thereof. [Figure 14] FIG. 2(a) is a side view showing a schematic configuration of a second engagement member, and FIG. 2(b) is a rear view showing the schematic configuration thereof. [Figure 15](a) is a front view of the schematic configuration as seen from the direction of arrow J in Figure 13(a), (b) is a rear view of the schematic configuration as seen from the direction of arrow K in Figure 13(a), and (c) is a rear view of the schematic configuration as seen from the direction of arrow L in Figure 13(a). [Figure 16] (a) is a schematic front view of the configuration as seen from the direction of the arrow M in Figure 14(a), (b) is a schematic plan view of the configuration as seen from the direction of the arrow N in Figure 14(a), and (c) is a schematic rear view of the configuration as seen from the direction of the arrow O in Figure 14(a). [Figure 17] FIG. 3 is a cross-sectional view showing a schematic configuration of a first engagement member. [Figure 18] FIG. 4 is a cross-sectional view showing a schematic configuration of a second engagement member. [Figure 19] 1A to 1C are explanatory views for explaining a method of assembling the interspinous spacer according to the present invention. [Figure 20] 1A to 1C are explanatory views for explaining a method of assembling the interspinous spacer according to the present invention. [Figure 21] 1A to 1C are explanatory views for explaining a method of assembling the interspinous spacer according to the present invention. [Figure 22] 1A to 1C are explanatory views for explaining a method of assembling the interspinous spacer according to the present invention. [Figure 23] 1A to 1C are explanatory views illustrating a method of placing the interspinous process spacer according to the present invention between spinous processes. [Figure 24] 1A to 1C are explanatory views illustrating a method of placing the interspinous process spacer according to the present invention between spinous processes. [Figure 25] 1 is an explanatory diagram for explaining the effect of the interspinous process spacer according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] An interspinous spacer 1 according to the present invention will be described below with reference to the accompanying drawings. Note that each drawing is partially enlarged or reduced to facilitate understanding of the configuration. FIG. 1 is a schematic side view of the interspinous spacer 1 according to the present invention, and FIG. 2 is a schematic cross-sectional view of the interspinous spacer 1. The interspinous spacer 1 according to the present invention is a device for maintaining a predetermined distance between adjacent spinous processes, and as shown in FIGS. 1 and 2 and the component diagram (partially omitted) in FIG. 3, includes a first expansion member 2, a second expansion member 3, a bolt member 4, a first engagement member 5, and a second engagement member 7. Note that the first expansion member 2, the second expansion member 3, the bolt member 4, the first engagement member 5, and the second engagement member 7 are preferably made of a biocompatible metallic material such as a titanium alloy or stainless steel.

[0019] This interspinous spacer 1 is configured so that, by rotating the bolt member 4 and moving the first expansion member 2 and the second expansion member 3 toward each other, the first and second engagement members 5 and 3 can be slid away from each other in a direction perpendicular to the longitudinal direction of the bolt member 4 from a first state in which the first engagement member 5 and the second engagement member 7 are in contact with each other, as shown in FIG. 4, along a direction perpendicular to the longitudinal direction of the bolt member 4. Furthermore, by rotating the bolt member 4 and moving the first and second expansion members 2 and 3 in a direction in which they are separated from each other, the first and second engagement members 5 and 7 can be slid away from each other from a second state in which they are separated from each other toward the first state. Note that FIG. 4(a) is a schematic side view of the interspinous spacer in the second state, and FIG. 4(b) is a schematic cross-sectional view of the same.

[0020] 1, the interspinous process spacer 1 according to this embodiment is configured to be bullet-shaped in the first state in which the first engagement member 5 and the second engagement member 7 are in contact with each other, and a substantially conical screw portion 1a is formed on the distal end of the spacer. This screw portion 1a is configured by combining a part of the first expansion member 2, the distal end of the first engagement member 5, and the distal end of the second engagement member 7, and is integrally configured to have a screw thread that can be screwed between the spinous processes.

[0021] The first expansion member 2 is a member that is placed on the spacer tip side of the interspinous spacer 1, and as shown in Figure 5(a), a schematic side view of the configuration, and Figure 5(b), a schematic rear view of the configuration as seen from the direction of arrow A in Figure 5(a), it comprises a screw tip portion 21 that forms the tip end of the screw portion 1a, and a rectangular pillar-shaped bolt connection portion 22 that is connected to the screw tip portion 21 and extends toward the base end side of the spacer opposite the spacer tip side, and has a female thread portion into which the bolt member 4 can be screwed.

[0022] On the spacer base end side of the screw tip 21 of the first expansion member 2, as shown in Figures 5(a) and (b), Figure 6(a) which is a schematic plan view of the configuration as seen from the direction of arrow B in Figure 5(a), and Figure 6(b) which is a schematic back view of the configuration as seen from the direction of arrow C in Figure 5(a), a first inclined surface 23 is formed relative to the first expansion member 2, along which the first engagement member 5 can slide diagonally, and a second inclined surface 24 which is inclined opposite to the first inclined surface 23 and along which the second engagement member 7 can slide diagonally. The first inclined surface 23 and the second inclined surface 24 are formed at positions projecting from the rectangular pillar-shaped bolt connection portion 22, with the first inclined surface 23 facing the first engaging member 5 and the second inclined surface 24 facing the second engaging member 7. As shown in FIG. 5(a), the first inclined surface 23 and the second inclined surface 24 are formed so as to become more spaced apart from each other as they move from the bolt connection portion 22 side (the base end side of the spacer) toward the tip side of the spacer. The first inclined surface 23 is formed continuously up to the surface of the screw tip portion 21. Similarly, the second inclined surface 24 is also formed continuously up to the surface of the screw tip portion 21.

[0023] By forming the first inclined surface 23 and the second inclined surface 24, the side view shape of the screw tip portion 21 on the spacer base end side is formed to be V-shaped, as shown in Fig. 5(a). Side edge portions 21a, 21b on the spacer base end side of the V-shaped screw tip portion 21 are configured to have a first groove portion 25 and a second groove portion 26 that are cut toward the female thread portion into which the bolt member 4 can be threaded. The first groove portion 25 is formed in the side edge portion 21a close to the first inclined surface 23, and the second groove portion 26 is formed in the side edge portion 21b close to the second inclined surface 24. Furthermore, the longitudinal direction of the first groove portion 25 formed in the side edge portion 21a adjacent to the first inclined surface 23 is configured to be parallel to the inclination direction of the first inclined surface 23, and similarly, the longitudinal direction of the second groove portion 26 formed in the side edge portion 21b adjacent to the second inclined surface 24 is configured to be parallel to the inclination direction of the second inclined surface 24.

[0024] Here, rail portions are formed between first groove portion 25 and first inclined surface 23 and between second groove portion 26 and second inclined surface 24, and with respect to these rail portions as well, the longitudinal direction of first rail portion 27 formed on the first inclined surface 23 side is configured to be parallel to the inclination direction of first inclined surface 23, and similarly, the longitudinal direction of second rail portion 28 formed on the second inclined surface 24 side is configured to be parallel to the inclination direction of second inclined surface 24. Furthermore, one side of first rail portion 27 formed on the first inclined surface 23 side constitutes a part of first inclined surface 23, and one side of second rail portion 28 formed on the second inclined surface 24 side constitutes a part of second inclined surface 24. Furthermore, the height of the first rail portion 27 formed on the first inclined surface 23 side (height from the side of the bolt connection portion 22) is configured to be approximately the same as the depth of the first tip groove portion 57 formed in the first engaging member 5 described below, and similarly, the height of the second rail portion 28 formed on the second inclined surface side (height from the side of the bolt connection portion 22) is configured to be approximately the same as the depth of the second tip groove portion 76 formed in the second engaging member 7 described below.

[0025] The second expansion member 3 is a member disposed on the base end side of the interspinous spacer 1, opposite the spacer distal end side, and is configured to be able to freely rotatably support the bolt member 4 on the bolt head 41 side. As shown in the schematic configuration side view of FIG. 7(a), the schematic configuration cross-sectional view of FIG. 7(b), FIG. 7(c) which is a schematic configuration front view seen from the direction of arrow D in FIG. 7(a), FIG. 8(a) which is a schematic configuration plan view seen from the direction of arrow E in FIG. 7(a), FIG. 8(b) which is a schematic configuration rear view seen from the direction of arrow F in FIG. 7(a), and FIG. 8(c) which is a schematic configuration rear view seen from the direction of arrow G in FIG. 7(a), the second expansion member 3 includes a wedge-shaped portion 33 formed with a third inclined surface 31 along which the first engagement member 5 can slide obliquely, and a fourth inclined surface 32 that is inclined opposite to the third inclined surface 31 and along which the second engagement member 7 can slide obliquely, and a through hole 34 into which the bolt member 4 is inserted. The third inclined surface 31 is configured as a surface facing the first engaging member 5, and the fourth inclined surface 32 is configured as a surface facing the second engaging member 7. As shown in FIG. 7(a), the third inclined surface 31 and the fourth inclined surface 32 are formed so as to become more spaced apart from each other from the tip side of the wedge-shaped portion 33 (the tip side of the spacer) toward the base end side of the spacer. A cylindrical end portion 35 is connected to the base end side of the spacer of the wedge-shaped portion 33, and one end of a through hole 34 opens in an end surface 354 facing the base end side of the spacer. The other end of the through hole 34 opens at the center position of the tip end of the wedge-shaped portion 33 (the center position of the sharp side).

[0026] As shown in FIGS. 7( a) and 7(c), the surface (side surface) of the wedge-shaped portion 33 sandwiched between the third inclined surface 31 and the fourth inclined surface 32 is configured to include a third groove 36 and a fourth groove 37 cut toward the through hole 34. The third groove 36 is formed in the side edge portion 31a adjacent to the third inclined surface 31, and the fourth groove 37 is formed in the side edge portion 32a adjacent to the fourth inclined surface 32. The longitudinal direction of the third groove 36 formed in the side edge portion 31a adjacent to the third inclined surface 31 is configured to be parallel to the inclination direction of the third inclined surface 31, and similarly, the longitudinal direction of the fourth groove 37 formed in the side edge portion 32a adjacent to the fourth inclined surface 32 is configured to be parallel to the inclination direction of the fourth inclined surface 32.

[0027] Here, rail portions are formed between the third groove portion 36 and the third inclined surface 31 and between the fourth groove portion 37 and the fourth inclined surface 32, and with regard to these rail portions as well, the longitudinal direction of the third rail portion 38 formed on the third inclined surface 31 side is configured to be parallel to the inclination direction of the third inclined surface 31, and similarly, the longitudinal direction of the fourth rail portion 39 formed on the fourth inclined surface side is configured to be parallel to the inclination direction of the fourth inclined surface 32. Furthermore, one side of the third rail portion 38 formed on the third inclined surface 31 side constitutes a part of the third inclined surface 31, and one side of the fourth rail portion 39 formed on the fourth inclined surface 32 side constitutes a part of the fourth inclined surface 32. In addition, the height of the third rail portion 38 formed on the third inclined surface 31 side is configured to be approximately the same as the depth of the first base end side groove portion formed in the first engaging member 5 described below, and similarly, the height of the fourth rail portion 39 formed on the fourth inclined surface side is configured to be approximately the same as the depth of the second base end side groove portion formed in the second engaging member 7 described below.

[0028] As shown in the cross-sectional view of FIG. 7(b), the through hole 34 formed in the second expansion member 3 is configured to include a first region 341 having the smallest inner diameter, a second region 342 connected to the first region 341, and a third region 343 connected to the second region 342. The first region 341 is located on the distal end side of the second expansion member 3, the third region 343 is located on the proximal end side (spacer proximal end side) of the second expansion member 3, and the second region 342 is located between the first region 341 and the second region 342. The inner diameter of the second region 342 is configured to be larger than the inner diameter of the first region 341, and the inner diameter of the third region 343 is configured to be larger than the inner diameter of the second region 342. One end of the first region 341 opens at the distal end side of the wedge-shaped portion 33, and one end of the third region 343 opens at the end face of the end portion.

[0029] The inner diameter of the first region 341 is slightly larger than the outer diameter of a first enlarged diameter portion 422a formed on a cylindrical shank 422 of a shaft 42 of the bolt member 4 (described later). The inner diameter of the second region 342 is slightly larger than the outer diameter of a second enlarged diameter portion 422b formed on the cylindrical shank 422. The third region 343 is an end face recess capable of accommodating the bolt head 41 of the bolt member 4, and its inner diameter is large enough to allow the accommodated bolt head 41 to rotate within the third region 343 (end face recess) using a rotating jig or the like. The opening edge 343a of the third region 343 (end face recess) is rectangular, and its longitudinal direction (the longitudinal direction of the long side of the rectangular opening edge) is set to be along the deformation direction when the interspinous process spacer 1 is deformed from the first state to the second state.

[0030] A pair of through holes 3a, 3a are formed in the side surface of the second expansion member 3, and a predetermined restriction pin 3b can be inserted therein. The axial direction of each through hole 3a, 3a is set to be perpendicular to the deformation direction when the interspinous process spacer 1 according to the present invention is deformed from the first state to the second state. As shown in FIG. 9, which shows the H-H cross section of FIG. 7(a), each through hole 3a, 3a, is configured to communicate with the through hole 34, in which the bolt member 4 is disposed, at a position spanning the first region 341 and the second region 342 of the through hole 34. In other words, a portion of the inner circumferential surface of each through hole 3a, 3a, is connected to the inner circumferential surface of the first region 341, and the other portion of the inner circumferential surface of each through hole 3a, 3a, is configured to be connected to the inner circumferential surface of the second region 342.

[0031] The bolt member 4 is a member that connects the first expansion member 2 and the second expansion member 3. As shown in the schematic side view of FIG. 10, the bolt member 4 is configured, for example, as a partially threaded bolt member and includes a bolt head 41 and a shaft 42. The bolt member 4 also has a central through-hole formed along its axis. The shaft 42 has a male-threaded shank 421 having a male thread and a cylindrical shank 422 that does not have a male thread on the bolt head 41 side. The cylindrical shank 422 is formed with a pair of ring-shaped enlarged diameter portions 422a, 422b that protrude radially outward and are arranged at a predetermined interval along the axial direction of the cylindrical shank 422. The distance between the enlarged diameter portions is set to be larger than the diameter of the above-mentioned restriction pin 3b. Of the pair of enlarged diameter portions 422a, 422b, the outer diameter of the first enlarged diameter portion 422a located on the male screw shaft portion 421 side is configured to be smaller than the outer diameter of the second enlarged diameter portion 422b located on the bolt head 41 side. In this embodiment, the outer diameter of the second enlarged diameter portion 422b is configured to be larger than the maximum outer dimension of the bolt head 41. The bolt member 4 configured as described above is inserted into the through hole 34 from the end side of the second expansion member 3. As shown in the enlarged cross-sectional view of the main part in FIG. 11 , after the bolt member 4 is inserted and placed in the through hole 34, the restriction pins 3b are fitted into the through holes 3a, 3a, and the tip ends of the restriction pins 3b are positioned in the region between the pair of enlarged diameter portions 422a, 422b, whereby the second expansion member 3 can support the bolt member 4 on the bolt head 41 side so that it can freely rotate.

[0032] 12, pin receiving recesses 44 capable of receiving a portion of the shank surface of the restriction pin 3b are formed on the end face of the second enlarged diameter portion 422b (the enlarged diameter portion of the pair of enlarged diameter portions that is disposed on the bolt head 41 side) facing the first enlarged diameter portion 422a, i.e., the end face that faces the shank of the restriction pin 3b (restriction pin facing surface 43). A plurality of these pin receiving recesses 44 are formed radially around the axis of the cylindrical shaft portion 422 on the restriction pin facing surface 43. The installation positions of the pin receiving recesses 44 are preferably set so as to be equiangularly spaced around the axis of the cylindrical shaft portion 422.

[0033] The first engagement member 5 and the second engagement member 7 are members that constitute the central portion of the interspinous spacer 1, and when the first state shown in Figure 1 is formed, the first engagement member 5 and the second engagement member 7 abut against each other and are formed to form a bullet shape together with the first expansion member 2. As shown in the schematic side view of Figure 13(a) and the schematic plan view of Figure 13(b), a portion of the screw portion 1a is formed on the surface of the distal end side (spacer distal end side) of the first engagement member 5, and similarly, as shown in the schematic side view of Figure 14(a) and the schematic back view of Figure 14(b), a portion of the screw portion 1a is also formed on the surface of the distal end side (spacer distal end side) of the second engagement member 7.

[0034] The first engaging member 5 and the second engaging member 7 are formed with a first recess 51 and a second recess 71 for receiving the spinous process surfaces in a spacer intermediate portion between the spacer distal end side and the spacer proximal end side. The recess depth of the first recess 51 formed in the first engaging member 5 and the recess depth of the second recess 71 formed in the second engaging member 7 are different from each other. The first recess 51 formed in the first engaging member 5 is configured as a recess that is recessed in a direction opposite to the moving direction when the first engaging member 5 moves from the first state to the second state, while the second recess 71 formed in the second engaging member 7 is configured as a recess that is recessed in a direction opposite to the moving direction when the second engaging member 7 moves from the first state to the second state. In this embodiment, the recess depth of the second recess 71 is configured to be greater than the recess depth of the first recess 51.

[0035] Furthermore, the first engaging member 5 has a semi-ring-shaped first stopper portion 52 that protrudes outward from its surface on the base end side of the spacer, and the second engaging member 7 also has a semi-ring-shaped second stopper portion 72 that protrudes outward from its surface on the base end side of the spacer. When the interspinous spacer 1 is in the first state described above, the first stopper portion 52 and the second stopper portion 72 are configured to be integrated with each other to form a ring shape.

[0036] Furthermore, the first engagement member 5 has a pair of through holes 53, 53 in its spacer intermediate region, and the second engagement member 7 similarly has a pair of through holes 73, 73 in its spacer central region. One of the through holes 53 formed in the first engagement member 5 and one of the through holes 73 formed in the second engagement member 7 are formed on the same axis. Similarly, the other of the through holes 53 formed in the first engagement member 5 and the other of the through holes 73 formed in the second engagement member 7 are formed on the same axis. Note that each of the through holes 53, 73 formed in the first engagement member 5 and the second engagement member 7 is formed as a through hole whose axial direction is along the direction in which the interspinous spacer 1 deforms from the first state to the second state.

[0037] A cylindrical guide member 9 (guide pin) is inserted and positioned through one of the through-holes 53 formed in the first engagement member 5 and one of the through-holes 73 formed in the second engagement member 7 (see FIG. 4( a)). Similarly, another guide member 9 is inserted and positioned through the other of the through-holes 53 formed in the first engagement member 5 and the other of the through-holes 73 formed in the second engagement member 7. The longitudinal direction of each guide member 9 is aligned with the direction in which the interspinous spacer 1 transforms from the first state to the second state, and the first engagement member 5 and the second engagement member 7 are configured to be movable between the first state and the second state with the pair of guide members 9 interposed therebetween. Furthermore, various structures can be adopted as the guide structure for the first engagement member 5 and the second engagement member 7, as long as the first engagement member 5 and the second engagement member 7 can be smoothly moved between the first state and the second state. For example, in this embodiment, the guide member 9 is formed as a cylindrical rod-like member, but it may also be configured as a flat plate-like member.

[0038] As shown in FIG. 13 , FIG. 15( a), which is a schematic front view of the first engaging member 5 as viewed from the direction of arrow J in FIG. 13( a), FIG. 15( b), which is a schematic rear view of the first engaging member 5 as viewed from the direction of arrow K in FIG. 13( a), and FIG. 15( c), which is a schematic rear view of the first engaging member 5 as viewed from the direction of arrow L in FIG. 13( a), the first engaging member 5 includes a first contact surface 54, a first side surface 55, and a pair of wall members 56. The wall members 56 are configured to be parallel to each other. The first contact surface 54 is a portion that forms a surface facing the direction of deformation when the interspinous spacer 1 according to the present invention is transformed from the first state to the second state, and the first side surface 55 is a portion that faces perpendicular to the direction of deformation when the interspinous spacer 1 is transformed from the first state to the second state. The wall members 56 are members that extend from the first contact surface 54 in a direction opposite to the direction of deformation when the interspinous spacer 1 is transformed from the first state to the second state. The first side surface portion 55 and the wall member 56 are respectively disposed on both sides of the bolt member 4. A portion of the screw portion 1a formed in the first engaging member 5 and the half-ring-shaped first stopper portion 52 are formed on predetermined surfaces of the first abutment surface portion 54 and the first side surface portion 55. Furthermore, the first recess 51 and the through hole 53 that receive the spinous process surface are formed on predetermined surfaces of the first abutment surface portion 54. Furthermore, a recess 531 that connects to the through hole 53 is formed on the outer surface of each wall member 56. This recess 531 is a recess that receives a portion of the shank surface of the above-mentioned guide member 9.

[0039] The shape of a distal edge 551 on the distal side (spacer distal side) of the first side surface portion 55 and the shape of a proximal edge 552 on the proximal side (spacer proximal side) of the first side surface portion 55 are inclined so as to be spaced apart from each other in the deformation direction when the interspinous spacer 1 is deformed from the first state to the second state. The inclination angle of the side edge 551 on the distal side of the first side surface portion 55 is configured to have the same inclination angle as the first inclined surface 23 of the first expansion member 2, and the inclination angle of the side edge 552 on the proximal side of the first side surface portion 55 is configured to have the same inclination angle as the third inclined surface 31 of the second expansion member 3. In addition, the shape of the side edge 553 in the central portion of the first side surface portion 55 is formed in a V-shape. More specifically, one side edge 553a of the central portion side edge 553 on the spacer tip side and another side edge 553b of the central portion side edge 553 on the spacer base end side are inclined so as to approach each other along the deformation direction when the interspinous spacer 1 is transformed from the first state to the second state. In the first state, the side edge of the second side surface portion 75 of the second engagement member 7 abuts against the central portion side edge 553.

[0040] Each wall member 56 is covered by the second side surface portion 75 of the second engagement member 7 when the interspinous spacer 1 is in the first state, and is positioned closer to the bolt member 4 than the second side surface portion 75 of the second engagement member 7. As shown in the schematic side view of FIG. 13( a), each wall member 56 has a side edge portion 561 located on the spacer distal end side and a side edge portion 562 located on the spacer proximal end side, and these side edges 561, 562 are formed at an inclination so as to be spaced apart from each other in the deformation direction when the interspinous spacer 1 is transformed from the first state to the second state. The inclination angle of the side edge portion 561 located on the spacer distal end side is configured to have the same inclination angle as the first inclined surface 23 of the first expansion member 2, and is connected to the side edge 551 on the distal side of the first side surface portion 55 described above. In addition, the inclination angle of the side edge portion 562 located on the base end side of the spacer is configured to have the same inclination angle as the third inclined surface 31 of the second expansion member 3, and is connected to the side edge 552 on the base end side of the above-mentioned first side surface portion 55.

[0041] The distance between each wall member 56 is set to be slightly larger than the width dimension of the bolt connection portion 22 in the first expansion member 2, and the first expansion member 2 is configured to be able to move in the area between each wall member 56.

[0042] As shown in the schematic cross-sectional view of FIG. 17 , the opposing surfaces 56 a of the wall members 56 are configured to connect to the end 54 a of the first abutment surface portion 54 on the spacer distal end side and the end 54 b of the first abutment surface portion 54 on the spacer proximal end side. Grooves are formed on the opposing surfaces 56 a of the wall members 56 near the side edges 561, 562. The first distal groove 57 formed near the side edge 561 located on the spacer distal end side is formed parallel to the side edge 561. That is, the formed first distal groove 57 is configured to have the same inclination angle as the first inclined surface 23 of the first expansion member 2. Similarly, the first proximal groove 58 formed near the side edge 562 located on the spacer proximal end side is formed parallel to the side edge 562. That is, the formed first proximal groove 58 is configured to have the same inclination angle as the third inclined surface 31 of the second expansion member 3. One end of the first distal groove 57 is formed at the end of the first engaging member 5 on the spacer distal end side, and the other end is formed at the lower end of the side edge of the wall member 56. Similarly, one end of the first proximal groove 58 is formed at the end of the first engaging member 5 on the spacer proximal end side, and the other end is formed at the lower end of the side edge of the wall member 56.

[0043] Groove portions (first tip groove portion 57 and first base groove portion 58) are formed on the opposing surfaces of each wall member 56, thereby forming rail portions between each side edge portion and the groove portion.With regard to these rail portions, the first tip rail portion 59 formed on the tip side of the spacer is configured to have the same inclination angle as the first inclined surface 23 of the first expansion member 2, and the first base rail portion 60 formed on the base side of the spacer is configured to have the same inclination angle as the second inclined surface 24 of the second expansion member 3.

[0044] Here, the first distal rail portion 59 formed on the distal end side of the spacer is inserted into the first groove portion 25 formed in the side edge portion adjacent to the first inclined surface 23 of the first expansion member 2, and the first rail portion 27 formed in the side edge portion adjacent to the first inclined surface 23 of the first expansion member 2 is inserted into the first distal groove portion 57 formed on the distal end side of the spacer, thereby allowing the first engagement member 5 to slide relative to the first expansion member 2. Similarly, the first proximal rail portion 60 formed on the proximal end side of the spacer is inserted into the third groove portion 36 formed in the side edge portion adjacent to the third inclined surface 31 of the second expansion member 3, and the third rail portion 38 formed in the side edge portion adjacent to the third inclined surface 31 of the second expansion member 3 is inserted into the first proximal groove portion 58 formed on the proximal end side of the spacer, thereby allowing the first engagement member 5 to slide relative to the second expansion member 3.

[0045] 14(a) , 16(a) , 16(b) , 16(c) , 16(c) , 16(a) , 16(b) , 16(c) , 16(c) , 16(c) , 16(b) , 16(c) , 16(c) , 16(c) , 16(b) , 16(c) , 16(c) , 16(c) , 16(a) , 16(b) , 16(c) , 16(c) , 16(c) , 16(c) , 16(a) , 16(b) , 16(c) , 16(c) , 16(c) , 16(c) , 16(c) , 16(a) , 16(c ... In addition, a second recess 71 for receiving the surface of the spinous process is formed on a predetermined surface of the second contact surface portion 74 .

[0046] The second side surface portion 75 of the second engagement member 7 is configured to have a shape that covers and conceals the wall member 56 of the first engagement member 5 in the first state. The side edge 751 of this second side surface portion 75 is V-shaped. More specifically, as shown in FIG. 14( a), one side edge 751a of the side edge 751 on the spacer distal side and another side edge 751b of the side edge 751 on the spacer proximal side are inclined so as to move away from each other in the deformation direction when the interspinous spacer 1 is transformed from the first state to the second state. The inclination angle of the one side edge 751a on the spacer distal side of the side edge 751 is configured to have the same inclination angle as the second inclined surface 24 of the first expansion member 2, and the inclination angle of the other side edge 751b arranged on the spacer proximal side is configured to have the same inclination angle as the fourth inclined surface 32 of the second expansion member 3. An inner surface 75a of the second side surface portion 75 (the surface facing the bolt member 4 in the first state) is formed to be a surface that is approximately parallel to the outer surface of the wall member 56, and is provided with a recess 731 that receives part of the surface of the shaft of the above-mentioned guide member 9. This recess 731 is formed to be continuous with the through hole 73.

[0047] As shown in the schematic cross-sectional view of FIG. 18 , grooves are formed on the inner surface 75a of the second side surface portion 75 near each of the side edges 751a and 751b. The second distal groove 76 formed near the side edge 751a located on the spacer distal end side is parallel to the side edge 751a. That is, the formed second distal groove 76 is configured to have the same inclination angle as the second inclined surface 24 of the first expansion member 2. Similarly, the second proximal groove 77 formed near the side edge 751b located on the spacer proximal end side is parallel to the side edge 751b. That is, the formed second proximal groove 77 is configured to have the same inclination angle as the fourth inclined surface 32 of the second expansion member 3. One end of the second distal groove 76 is formed at the end of the second engagement member 7 on the spacer distal end side, and the other end is formed at the upper end of the second side surface portion 75. Similarly, one end of the second base end groove portion 77 is formed at the end of the first engaging member 5 on the spacer base end side, and the other end is formed at the upper end of the second side portion 75.

[0048] Groove portions (second tip groove portion 76 and second base groove portion 77) are formed on the inner surface 75a of each second side portion 75, so that rail portions are formed between the side edges of the second side portion 75 and the groove portions. With regard to these rail portions, the second tip rail portion 78 formed on the tip side of the spacer is configured to have the same inclination angle as the second inclined surface 24 of the first expansion member 2, and the second base rail portion 79 formed on the base side of the spacer is configured to have the same inclination angle as the fourth inclined surface 32 of the second expansion member 3.

[0049] Here, the second distal rail portion 78 formed on the distal end side of the spacer is inserted into the second groove portion 26 formed on the side edge portion adjacent to the second inclined surface 24 of the first expansion member 2, and the second rail portion 28 formed on the side edge portion adjacent to the second inclined surface 24 of the first expansion member 2 is inserted into the second distal groove portion 76 formed on the distal end side of the spacer, thereby allowing the second engagement member 7 to slide relative to the first expansion member 2. Similarly, the second proximal rail portion 79 formed on the proximal end side of the spacer is inserted into the fourth groove portion 37 formed on the side edge portion adjacent to the fourth inclined surface 32 of the second expansion member 3, and the fourth rail portion 39 formed on the side edge portion adjacent to the fourth inclined surface 32 of the second expansion member 3 is inserted into the second proximal groove portion 77 formed on the proximal end side of the spacer, thereby allowing the second engagement member 7 to slide relative to the second expansion member 3.

[0050] The interspinous spacer 1 having the first expansion member 2, second expansion member 3, bolt member 4, first engagement member 5, and second engagement member 7 configured as described above can be assembled, for example, as follows: As shown in FIG. 19( a), the first distal rail portion 59 of the first engagement member 5 is inserted into the first groove 25 of the first expansion member 2, and the first rail portion 27 of the first expansion member 2 is inserted into the first distal groove 57 of the first engagement member 5. The first engagement member 5 is then slid relative to the first expansion member 2 to complete the assembly as shown in FIG. 19( b). Next, as shown in FIG. 20( a), the second proximal rail portion 79 of the second engagement member 7 is inserted into the fourth groove 37 of the second expansion member 3, and the fourth rail portion 39 of the second expansion member 3 is inserted into the second proximal groove 77 of the second engagement member 7. The second engagement member 7 is then slid relative to the second expansion member 3 to complete the assembly as shown in FIG. 20( b). 21(a), the first base-end rail portion 60 of the first engagement member 5 is inserted into the third groove portion 36 of the second expansion member 3 to which the second engagement member 7 is connected, and the third rail portion 38 of the second expansion member 3 is inserted into the first base-end groove portion 58 of the first engagement member 5. At the same time, the first distal-end rail portion 78 of the second engagement member 7 is inserted into the second groove portion 26 of the first expansion member 2 to which the first engagement member 5 is connected, and the second rail portion 28 of the first expansion member 2 is inserted into the first distal-end groove portion 76 of the second engagement member 7, and they are assembled as shown in FIG. 21(b). Next, as shown in FIGS. 22(a) and 22(b), the bolt member 4 is inserted into the second expansion member 3, and the male thread portion of the bolt member 4 is screwed into the bolt connection portion 22 of the first expansion member 2. Furthermore, a restricting pin 3b is fitted into each of a pair of through holes provided in the second expansion member 3. Finally, the interspinous spacer 1 is assembled by inserting the guide member 9 into the through-holes provided in the first engagement member 5 and the second engagement member 7. Note that the guide member 9 is configured to be crimped, for example, on the side of the through-hole 53 formed in the first engagement member 5 so as not to fall out.

[0051] The interspinous spacer 1 configured as described above is screwed between the spinous processes and installed, for example, as shown in Figures 23 and 24. The interspinous spacer 1 has a bullet-like shape with a screw portion 1a formed at the tip, so it can be easily screwed between the spinous processes (Figure 23(b)). When the screw portion 1a of the spinous spacer passes through the spinous processes, the central portion of the interspinous spacer 1 is sandwiched between the spinous processes (Figure 24(a)). At this time, the interspinous spacer 1 is installed so that the first recess 51 formed in the first engagement member 5 and the second recess 71 formed in the second engagement member 7 each face toward the spinous processes. Next, by rotating the bolt member 4 in a first direction using a specified jig, the first expansion member 2 and the second expansion member 3 move toward each other along the longitudinal direction of the bolt member 4, and as a result, the first engagement member 5 and the second engagement member 7 slide from the first state in which they abut each other to a direction in which they move away from each other along a vertical direction perpendicular to the longitudinal direction of the bolt member 4, allowing the surfaces of the spinous processes to be received in the first recess 51 of the first engagement member 5 and the second recess 71 of the second engagement member 7, thereby enabling stable expansion and fixation between the spinous processes (Figure 24(b)).

[0052] Furthermore, when removing the spinous process spacer, a predetermined jig is used to rotate the bolt member 4 in a second direction opposite to the first direction, causing the first expansion member 2 and the second expansion member 3 to move away from each other along the longitudinal direction of the bolt member 4, with the result that the first engagement member 5 and the second engagement member 7 return from the second state in which they are spaced apart to the first state. Thereafter, a separate predetermined jig can be used to rotate the interspinous process spacer in the opposite direction to the rotation direction when it was screwed in, allowing it to be removed from between the spinous processes.

[0053] In this way, the interspinous process spacer 1 of the present invention can stably expand and fix the space between the spinous processes by simply screwing it between the spinous processes and then rotating the bolt member 4 to expand the space between the first engaging member 5 and the second engaging member 7.Furthermore, removal can be done easily as described above, so the interspinous process spacer 1 can be installed in a short time, significantly reducing the burden on the doctor and the physical burden on the patient.

[0054] Furthermore, the interspinous spacer 1 according to the above embodiment is provided with a first recess 51 in the first engaging member 5 and a second recess 71 in the second engaging member 7. Providing these first recess 51 and second recess 71 makes it possible to receive the spinous process surfaces in an extremely stable manner, thereby enabling the interspinous spacer 1 to be installed with extremely high stability.

[0055] Furthermore, in the above embodiment, the recess depth of the first recess 51 of the first engaging member 5 and the recess depth of the second recess 71 of the second engaging member 7 are formed to be different from each other. The size of one spinous process facing the interspinous spacer 1 is usually different from the size of the other spinous process, and by setting the recess depth of the first recess 51 and the recess depth of the second recess 71 to be different as described above, the interspinous spacer 1 can be installed to match the size of the spinous processes as closely as possible. In other words, by setting the orientation of the spinous process spacer so that the second recess 71, which has a deeper recess, receives the larger spinous process, an even more stable installation of the interspinous spacer 1 is possible.

[0056] Furthermore, in the interspinous process spacer 1 according to the above embodiment, the first engagement member 5 is configured to include a half-ring-shaped first stopper portion 52, and the second engagement member 7 is also configured to include a half-ring-shaped second stopper portion 72. By providing these first stopper portion 52 and second stopper portion 72, when the interspinous process spacer 1 in the first state is screwed between the spinous processes, the first stopper portion 52 and the second stopper portion 72 abut against the side surfaces of the spinous processes, effectively preventing the interspinous process spacer 1 from being screwed beyond a predetermined position. Furthermore, this reliably prevents the interspinous process spacer 1 placed between the spinous processes from becoming displaced when the patient with the interspinous process spacer 1 placed therein moves about in daily life.

[0057] Furthermore, the interspinous process spacer 1 according to the above embodiment has a longitudinal direction perpendicular to the longitudinal direction of the bolt member 4, and includes a guide member 9 that connects the first engaging member 5 and the second engaging member 7, and is configured so that the first engaging member 5 and the second engaging member 7 can move between the first state and the second state with the guide member 9 interposed therebetween. By including such a guide member 9, it becomes possible to reliably move the first engaging member 5 and the second engaging member 7 in a direction perpendicular to the longitudinal direction of the bolt member 4 without causing misalignment between them.

[0058] In addition, in the above embodiment, the bolt member 4 is configured with a pair of ring-shaped enlarged diameter portions (first enlarged diameter portion 422a and second enlarged diameter portion 422b) arranged at a predetermined interval along the axial direction of the cylindrical shaft portion 422, and of the pair of enlarged diameter portions, the end face facing the first enlarged diameter portion 422a of the second enlarged diameter portion 422b arranged on the bolt head 41 side, that is, the end face facing the shaft portion of the regulating pin 3b (regulating pin opposing surface 43), is formed with a pin receiving recess 44 that can accept a portion of the shaft surface of the regulating pin 3b, as shown in the schematic configuration diagram of Figure 12. When the interspinous spacer 1 is screwed between the spinous processes and the first engaging member 5 and the second engaging member 7 are spread apart, it is possible to rotate the bolt member 4 to spread the first engaging member 5 and the second engaging member 7 apart without encountering much resistance in the initial stage, but once the first engaging member 5 and the second engaging member 7 begin to firmly press against the spinous processes, the first engaging member 5 and the second engaging member 7 will each receive a reaction force from the opposing spinous process (a force pushing the first engaging member 5 and the second engaging member 7 towards the bolt member 4). When the interspinous spacer 1 receives such a force, the second expansion member 3 receives a force directed toward the base end of the spacer, and as a result, the restriction pin 3b provided on the second expansion member 3 is pressed against the end face (restriction pin-opposing surface 43) of the second enlarged diameter portion 422b formed on the bolt member 4, as shown in the explanatory diagram of Figure 25, and a portion of the shank surface of the restriction pin 3b is received in the pin receiving recess 44 formed on the restriction pin-opposing surface 43. If the bolt member 4 is further rotated in this state, a portion of the shank surface of the restriction pin 3b will be received in another adjacent pin receiving recess 44, and at this time, the fingers of the doctor rotating the bolt member 4 can sense, as vibrations, that the pin receiving recess 44 into which the shank surface of the restriction pin 3b is received has changed. In other words, the occurrence of this vibration allows one to recognize that the first engagement member 5 and the second engagement member 7 have firmly begun to press against the spinous processes, and furthermore, by counting the number of vibrations that occur, one can determine the amount of threading of the bolt member 4, and from this amount of threading it is possible to determine whether or not the first engagement member 5 and the second engagement member 7 have reached a desirable distance.

[0059] Furthermore, in the above embodiment, an end surface recess for accommodating the recess of the bolt member 4 is formed at the end of the second expansion member 3 on the spacer base end side, and the opening edge of this end surface recess is rectangular in shape, with its longitudinal direction aligned with the deformation direction when the interspinous spacer 1 deforms from the first state to the second state. When such a configuration is adopted, the first recess 51 of the first engagement member 5 and the second recess 71 of the second engagement member 7 are located on the short side of the rectangular opening edge. In other words, when the interspinous spacer 1 is screwed between the spinous processes to install it in a predetermined position, the position of the short side of the opening edge can be used as a clue to easily determine whether the first recess 51 or the second recess 71 faces the predetermined intended installation surface of the spinous process.

[0060] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, in the above embodiments, the first engaging member 5 is configured to include the first recess 51, but the first engaging member 5 may be configured without the first recess 51. Furthermore, in the above embodiments, the recess depth of the first recess 51 formed in the first engaging member 5 and the recess depth of the second recess 71 formed in the second engaging member 7 are formed to be different from each other, but the first recess 51 and the second recess 71 may be configured as recesses having the same recess depth.

[0061] Furthermore, in the above embodiment, the second engaging member 7 is configured to include the second recess 71, but it may be configured not to include this second recess 71. Furthermore, in the above embodiment, the first engaging member 5 is configured to include the first stopper portion 52, but it may be configured not to include this first stopper portion 52. Furthermore, in the above embodiment, the second engaging member 7 is configured to include the second stopper portion 72, but it may be configured not to include this second stopper portion 72.

[0062] In addition, in the above embodiment, the end face (regulating pin opposing surface 43) of the second enlarged diameter portion 422b formed on the cylindrical shaft portion 422 of the bolt member 4, facing the first enlarged diameter portion 422a, has multiple pin receiving recesses 44 formed thereon that can receive a portion of the shaft surface of the regulating pin 3b, as shown in the schematic configuration diagram of Figure 12, but such pin receiving recesses 44 may be omitted.

[0063] Furthermore, the end of the second expansion member 3 on the base end side of the spacer is formed with an end-face recess for accommodating the recess of the bolt member 4. The opening edge shape of the end-face recess is rectangular, with the longitudinal direction aligned with the deformation direction of the interspinous spacer 1 when it transforms from the first state to the second state. However, this configuration is not particularly limited, and the opening edge shape may be rectangular, with the transverse direction aligned with the deformation direction when it transforms from the first state to the second state. Even with this configuration, when screwing the interspinous spacer 1 between the spinous processes and setting it in place, the position of the long side of the opening edge can be used as a clue to easily determine whether the first recess 51 or the second recess 71 faces the intended installation surface of the spinous process. Furthermore, the opening edge shape of the end-face recess is not limited to a rectangle and may be, for example, an elliptical shape. When the opening edge shape is formed as an ellipse, it is preferable to form it as an oblong shape so that the major and minor axes can be easily distinguished. Furthermore, instead of using the opening edge shape of the end face recess as a marker for the position where the first recess 51 and the second recess 71 are formed, as described above, it is also possible to configure the second expansion member 3 to have a marker such as a marking on the end portion on the base end side of the spacer. [Explanation of symbols]

[0064] 1 Interspinous spacer 2 First expansion member 21 Screw tip 21a, 21b side edge part 22 bolt connection 23 1st slope 24 Second slope 25 First groove 26 Second groove 27 First rail section 28 Second rail section 3 Second expansion member 3a Through hole 3b Regulatory pin 31 Third slope 32 4th slope 33 Cuneiform region 34 Through hole 35 Cylindrical End 36 Third groove 37 Fourth groove 38 Third rail section 39 4th rail section 4 Bolt members 41 Bolt head 42 shaft 421 Male threaded shaft 422 Cylindrical shaft 422a 1st enlarged diameter section 422b 2nd enlarged diameter section 43 Regulating pin facing surface 44 Pin receiving recess 5 First engagement member 51 First recess 52 First stopper part 53 Through hole 531 recess 54 1st contact surface part 55 First side part 551 Tip side edge 552 Proximal edge 553 Side edge of central part 56 Wall components 56a: Each opposing surface of the wall members 561 Side edge portion arranged on the tip side of the spacer 562 Side edge portion arranged on the base end side of the spacer 57 First tip gutter section 58 First base end gutter 59 First tip rail section 60 First base end rail 7 Second engagement member 71 Second recess 72 Second stopper part 73 Through Hole 731 recess 74 Second contact surface part 75 Second side part 75a Inner surface of second side edge 751 Side edge of second side part 76 Second tip gutter section 77 Second base end gutter 78 Second tip rail section 79 Second base end side rail part 9 Guide member

Claims

1. An interspinous spacer for placement between adjacent spinous processes, comprising: The bolt assembly includes a first engaging member, a second engaging member, a bolt member disposed between the first engaging member and the second engaging member, a first expanding member, and a second expanding member, the first expansion member is threadedly engaged with the tip end side of the bolt member, and the second expansion member is configured to be able to support the bolt member at a bolt head side so as to be freely rotatable, the first expansion member and the second expansion member are configured to be movable toward each other along the longitudinal direction of the bolt member by rotation of the bolt member in a first direction, and to be movable away from each other along the longitudinal direction of the bolt member by rotation of the bolt member in a second direction, When the first expansion member and the second expansion member move in a direction toward each other, the first engagement member and the second engagement member are configured to be slidable from a first state in which they abut each other in a direction in which they move away from each other along a vertical direction perpendicular to the longitudinal direction of the bolt member, and when the first expansion member and the second expansion member move in a direction in which they move away from each other, the first engagement member and the second engagement member are configured to be slidable from a second state in which they are spaced apart from each other toward the first state, An interspinous spacer characterized in that, in the first state, the tip portion of the first engaging member on the tip side of the bolt member, the tip portion of the second engaging member on the tip side of the bolt member, and a portion of the first expansion member are integrated to form an approximately conical screw portion having a thread that can be screwed into the space between the spinous processes.

2. In the first state, the overall shape of the interspinous process spacer is configured to be bullet-shaped having a spacer distal end side where the screw portion is formed and a spacer proximal end side opposite to the distal end side, the first expansion member includes a screw tip portion that constitutes a tip portion of the screw portion, and a bolt connection portion that is connected to the screw tip portion, extends toward the base end side of the spacer, and has a female thread portion into which the bolt member can be threaded, a first inclined surface on which the first engaging member can slide obliquely relative to the first expansion member, and a second inclined surface inclined opposite to the first inclined surface and on which the second engaging member can slide obliquely relative to the first expansion member are formed on the base end side of the spacer at the distal end of the screw; The interspinous process spacer according to claim 1, characterized in that the second expansion member is arranged on the base end side of the spacer and has a wedge-shaped portion formed with a third inclined surface along which the first engagement member can slide diagonally, and a fourth inclined surface inclined opposite to the third inclined surface along which the second engagement member can slide diagonally, and a through hole formed in the wedge-shaped portion through which the bolt member is inserted.

3. The interspinous spacer according to claim 2, characterized in that, in the spacer intermediate portion between the spacer distal side and the spacer proximal side, the first engaging member and the second engaging member each have a recess formed therein to receive the spinous process surface.

4. The interspinous spacer according to claim 3, wherein the recess depth formed in the first engagement member and the recess depth formed in the second engagement member are formed to be different from each other.

5. The interspinous process spacer according to claim 2, characterized in that, at the base end side of the spacer, the first engaging member has a semi-ring-shaped first stopper portion protruding outward from its surface, and the second engaging member has a semi-ring-shaped second stopper portion protruding outward from its surface.

6. The interspinous process spacer according to claim 5 , wherein in the first state, the first stopper portion and the second stopper portion are integrated with each other to form a ring shape.

7. a guide member having a longitudinal direction perpendicular to the longitudinal direction of the bolt member and connecting the first engaging member and the second engaging member, The interspinous spacer according to claim 1 or claim 2, wherein the first engagement member and the second engagement member are configured to be movable between the first state and the second state with the guide member interposed therebetween.

8. The bolt member includes a bolt head and a shaft body, and the shaft body is a partially threaded bolt member having a male threaded shank portion on which a male thread is formed and a cylindrical shank portion on the bolt head side where no male thread portion is formed, The cylindrical shaft portion is formed with a pair of ring-shaped enlarged diameter portions that protrude radially outward and are arranged at a predetermined interval along the axial direction of the cylindrical shaft portion, The second expansion member has a through hole formed therein, the through hole extending in a vertical direction perpendicular to the longitudinal direction of the half-threaded bolt member, The interspinous process spacer according to claim 1 or 2, further comprising a restriction pin that is inserted into the through-hole and has a tip end positioned in the region between the pair of enlarged diameter portions.

9. Of the pair of enlarged diameter portions, the enlarged diameter portion disposed on the bolt head side has a shank facing surface that faces the shank of the restriction pin, a pin receiving recess capable of receiving a part of the shaft surface of the restriction pin is formed in the shaft portion opposing surface; The interspinous process spacer according to claim 8 , wherein a plurality of the pin receiving recesses are formed on the shaft portion facing surface radially around the axis of the cylindrical shaft portion.

10. The interspinous spacer according to claim 1 or 2, characterized in that the second expansion member has an end surface recess capable of accommodating the bolt head of the bolt member, and the opening edge shape of the end surface recess is formed into a rectangular or elliptical shape.

Images