Bone anchor with plug member and tool for inserting the plug member into the bone anchor

0001The present invention relates to a bone fixture having a tubular shaft and a plug member that can be fitted into the shaft to close the shaft at one end thereof.<u style="single">.. Bone</u>Fixtures are particularly suitable for use in minimally invasive surgery (MIS).

0002Patent Document 1 describes a bone fixture in the form of a bone screw having a screw head and a threaded shaft portion provided with one axial hole and a plurality of radial holes. The axial hole opens on the screw head side and closes on the free end side of the threaded shaft. This known bone screw can be fixed in the bone by injecting bone cement into the shaft. This provides permanent and safe bone fixation.

0003A bone fixture in the form of a bone screw having a tubular shaft portion is also known from Patent Document 2. Inside the bone screw, a continuous longitudinal conduction path and a lateral conduction path connected to the longitudinal conduction path and extending in the radial direction are provided. The longitudinal conduction path opens at both ends of the screw and can be connected to the vacuum pump via a tube in the area around the screw head to aspirate blood and other substances.

0004Patent Documents 3 to 5 disclose a bone screw having a tubular threaded portion and a tip portion connectable to the portion. Numerous depressions are provided in the wall of the tubular threaded portion. This tubular threaded portion can be filled with bone cement.

0005Minimally invasive surgery is being applied in more and more cases. In minimally invasive surgery, guide wires may be used to place the implant at the implant location. In minimally invasive surgery, instruments are usually taken in and out percutaneously by touching the skin.

<p num="0006"><patcit num="1"><text>International Publication No. 01/26568</text></patcit><patcit num="2"><text>U.S. Pat. No. 5,047,030</text></patcit><patcit num="3"><text>International Publication No. 02/38054</text></patcit><patcit num="4"><text>U.S. Patent Application Publication No. 2004/0122431</text></patcit><patcit num="5"><text>U.S. Patent Application Publication No. 2004/0147929</text></patcit></p>

<p num="0007"> An object of the present invention is to provide a versatile bone fixture suitable for being placed in an implantable position, for example in minimally invasive surgery, and capable of filling bone cement and other substances. Is.</p>

<p num="0008"> This object is achieved by the bone fixture according to claim 1 and the tool according to claim 12. In addition, the expansion described in the dependent claims is possible.</p><p num="0009"> The bone fixtures of the present invention have the advantage that they can be used in both conventional and minimally invasive surgery. Attach a plug member to a ready-made tubular bone screw to make it suitable for minimally invasive surgery be able to.</p><p num="0010"> Bone fixation with a plug member prevents the injected bone cement from leaking from the tip of the bone fixture. This can reduce possible damage to the vascular structure.</p><p num="0011"> Further features and advantages of the present invention will be described in more detail by the description of embodiments based on the accompanying drawings.</p>

0012<figref num="1">It is an exploded perspective view of the bone fixture of the 1st Embodiment of this invention.</figref><figref num="2">It is a perspective view of the bone fixture shown in FIG. 1 in the assembled state when fixing the rod.</figref><figref num="3">FIG. 5 is a cross-sectional view of a cross section of the bone fixture shown in FIG. 2 cut along a surface including the central axis of the rod.</figref><figref num="4">It is a top view of the plug member used in the bone fixture shown in FIGS. 1 to 3.</figref><figref num="5">It is a perspective view of the plug member shown in FIG.</figref><figref num="6">It is a side view of the plug member shown in FIG.</figref><figref num="7">It is sectional drawing of the plug member shown in FIG.</figref><figref num="8">FIG. 5 is an enlarged cross-sectional view showing a state in which the plug member shown in FIGS. 4 to 7 is inserted into the bone fixture.</figref><figref num="9">It is an enlarged cross-sectional view which shows the bone fixture of the 2nd Embodiment in which another plug member was inserted.</figref><figref num="10">It is an enlarged cross-sectional view which shows the bone fixture of the 3rd Embodiment in which another plug member was inserted.</figref><figref num="11">It is an exploded perspective view which shows the 1st Embodiment of the tool for inserting a plug member into a bone fixture.</figref><figref num="12">FIG. 5 is a perspective view showing a bone fixture in which a plug member is incorporated in the tool shown in FIG.</figref><figref num="13">FIG. 5 is a perspective view of a bone fixture having the tool of the second embodiment at a position where bone cement is injected.</figref><figref num="14">It is an exploded perspective view of the bone fixture having the tool of the 2nd Embodiment.</figref><figref num="15">It is a figure which shows steps 1) to 3) using a bone fixture in minimally invasive surgery.</figref><figref num="16a)">It is a figure which shows the step 4) which uses the bone fixture in the minimally invasive surgery.</figref><figref num="16b)">It is a figure which shows the step 4) which uses the bone fixture in the minimally invasive surgery.</figref><figref num="16c)">It is a figure which shows the step 4) which uses the bone fixture in the minimally invasive surgery.</figref>

0013FIGS. 1 to 8 show the bone fixture of the first embodiment of the present invention. The bone fixing device 1 includes a bone fixing tool 2 for fixing the bone, a receiving portion 3 for receiving the rod 4, a pressing element 5 acting on the bone fixing tool 2, and a fixing element 6. The bone fixing device 1 of the present embodiment is designed as a so-called multi-axis bone screw, characterized in that the bone fixing device 2 is rotatably supported by a receiving portion 3 that connects the bone fixing device to the spinal column rod 4. ing. The angular position of the bone fixture relative to the rod can be fixed by the fixing element 6.

0014In particular, as shown in FIG. 3, the bone fixture 2 includes a shaft portion having a head portion 8 at the first end portion and a second end portion 9 which is a free end and can have a shape as a tip end. In this embodiment, the head 8 has a spherical portion. Further, the bone screw 10 is provided at least on the outer peripheral portion of the shaft portion 7.

0015The bone fixture is tubular and includes a nearly coaxial conduction hole 11 extending from the first end through the head 8 and shaft 7 to the second end 9. The portion 12 close to the second end 9 has a smaller diameter than the main portion of the shaft 7, thereby forming the shoulder 13 inside the shaft 7. An engagement structure 14 for engaging with a tool is provided at the free end of the head 8. The wall of the shaft portion 7 is provided with a plurality of openings 15 through which the conduction holes 11 and the outside pass. The number, size and arrangement of the openings 15 are designed with the overall dimensions of the bone fixture 2 taken into account for the purpose of forming an outlet for the bone cement or chemical material introduced into the bone fixture.

0016The diameter of the conduction hole 11 and in particular the diameter of the portion 12 are designed to guide the guide wires commonly used for minimally invasive surgery through bone fixtures.

0017The receiving portion 3 has a substantially cylindrical shape having a first end portion 3a and a second end portion on the opposite side, particularly as shown in FIGS. 1 to 3. The receiver 3 includes a coaxial hole 16, which extends from the first end to the second end and is rotatably supported by the receiver 3. 2 Tapered toward the end 16a. Further, the receiving portion has a substantially U-shaped recess 17 starting from the first end portion 3a and extending in the direction of the second end portion 3b, whereby two free leg portions 18a and 18b are formed. There is. The free legs 18a and 18b are provided with female threads 19 for screwing the fixing element 6. In this embodiment, the fixing element 6 is an internal thread.

0018The pressing element 5 acts to exert pressure on the head 8 of the bone fixture when the internal screw 6 is tightened to press the rod 4. The pressing element 5 is introduced into the coaxial hole 16 and is designed to be axially movable in it. The pressing element 5 is provided with a substantially spherical recess 20 on the side facing the head 8 for distributing pressure to the head 8, and a substantially cylindrical recess 21 on the opposite side for receiving the rod 4. To be equipped. The pressing element 5 also includes a coaxial hole 22 through which a guide wire or screw tool is passed.

0019As shown in FIGS. 4-8, the bone fixture further comprises a plug member 30 for closing the conduction hole 11 of the shaft portion 7 at the end portion 12 having the second end portion 9 which is a free end. The plug member 30 is a separated component that can be introduced into the conduction hole 11. In the embodiments shown in FIGS. 4-8, the plug member 30 includes a first cylindrical portion 31 having a diameter that fits into the end portion 12 of the shaft portion 7. A chamfered portion 32 may be provided at the free end of the first cylindrical portion 31 in order to facilitate the introduction of the plug member. On the opposite side of the chamfered portion 32, the plug member 30 includes a second cylindrical portion 33 having a diameter that fits into the inner diameter of the conduction hole 11. A transition portion 34 is provided between the first cylindrical portion 31 and the second cylindrical portion 33, and the transition portion 34 is a shoulder between the main portion of the conduction hole 11 and the end portion 12 having a reduced diameter. The shape may be adapted to the shape of the portion 13. Such a shoulder portion 13 forms a stop portion for introducing the plug member.

0020A plurality of upright gripping springs 35 are provided at the free ends of the second cylindrical portion 33. The gripping springs 35 are arranged in a circumferential shape having a diameter smaller than the diameter of the second cylindrical portion 33, and are elastic so as to be elastically movable outward and / or inward. Grip spring at free end The 35 includes a plurality of retaining portions 36, each of which is detachably engaged with a tool described below. The gripping springs 35 are arranged so that the outer portion of the retaining portion 36 does not protrude outward from the outer circumference of the second cylindrical portion 33.

0021As shown in FIG. 8, when the plug member 30 is completely inserted into the conduction hole 11, the bone cement or chemical substance introduced into the conduction hole 11 is prevented from leaking through the second end portion 9. , The plug member 30 closes the conduction hole 11 at the end portion 12.

0022The material forming the bone fixture, receiver, pressing element, and fixing screw can be any material commonly used in this type of device, especially suitable for the body, such as titanium, stainless steel, or alloys. Metals with properties, such as polyetheretherketone (hereinafter A resin that is compatible with the body, such as (denoted as "PEEK"), can be used. The rod can be made of metal or plastic depending on the application, i.e., depending on whether it provides mere fixation or dynamic stability. As the material of the plug member, the same material as the bone fixture or a different material can be used. Suitable materials for plug members are, in particular, titanium and titanium alloys, stainless steel used for implants, and PEEK.

0023A second embodiment of the plug member is shown in FIG. The plug member 40 has a spherical shape having a diameter larger than the inner diameter of the end portion 12 of the conduction hole 11 and smaller than the inner diameter of the conduction hole 11 of the main portion of the shaft portion 7. The spherical-shaped plug member 40 is preferably formed of a material having a high specific gravity such as metal so that the plug member 40 is inserted and dropped by its own weight.

0024FIG. 10 shows a third embodiment of the bone fixture using the plug member 41. The plug member 41 in this embodiment does not include the gripping spring 35 and engages with a tool instead of the gripping spring 35. It differs from the plug member 30 only in that the recess 42 is provided in the second cylindrical portion. Other parts are the same as the plug member 30.

0025Although a multiaxial bone screw has been shown as a bone fixing device with a bone fixing device, the present invention includes any other bone fixing device. For example, a uniaxial bone screw formed so that the head of the bone screw 2 receives the rod can be used. Bone fixtures may also not require having a bone screw on their shaft. Bone fixtures can also be designed as push-and-turn fixtures with spiny processes for retention within the bone. Bone fixtures can also be designed as bone nails with a smooth outer surface.

0026Other modifications of the plug member are also conceivable. For example, the plug member may have a disk shape, a conical shape, or any other shape.

0027Next, a first embodiment of the tool for inserting the plug member into the bone fixture will be described with reference to FIGS. 11 and 12. Tool 50 is particularly suitable for inserting the types of plug members shown in FIGS. 4-8. The tool 50 includes a handle 51 for gripping and an insertion tube 52 extending through the handle 51. The insertion tube 52 is hollow and has at least the same length as the shaft so that the plug member 30 can be positioned at the end of the conduction hole 11. The inner diameter of the insertion tube 52 is such that the insertion tube 52 can be placed on the grip portion 35 of the plug member, whereby the grip spring moves together with the retaining portion 36 inward of the insertion tube 52 to some extent. In this way, the receiving portion 36 is caught at the end of the insertion tube 52. The insertion tube 52 may have a recess at its end that engages with the retaining portion 36. The outer diameter of the insertion tube 52 is slightly smaller than the inner diameter of the conduction hole 11 so that the insertion tube 52 can be introduced into the conduction hole 11. The insertion tube 52 extends through the handle 51 so that the open end 53 of the insertion tube 52 is substantially aligned with the end of the handle 51. FIG. 11 shows the disassembled state of the bone fixture 2, the plug member 30, and the tool 50. In the state shown in FIG. 12, the stopper member 30 is gripped by the tool 50. Since the insertion tube 52 extends through the handle 51, the guide wire can be guided into the tube portion through the open end.

002813 and 14 show the two positional relationships of the tool with respect to the bone fixture in the second embodiment of the tool.

0029The head of this embodiment is formed by a syringe 60. Syringe 60 is particularly suitable for injecting bone cement or chemicals into bone fixture 2. Syringe 60 It comprises a cylindrical portion having a handle 61 for chewing and a plunger 62 that pushes bone cement or a chemical substance into a needle or tube 63. The needle or tube 63 is designed so that the plug member 30 can be gripped or fitted into the recess 42 of the plug member 41. The needle or tube 63 is long enough to allow the plug member to be placed at the end of the conduction hole 11.

0030Modifications of these tools are also conceivable. For example, the insertion tube 52 or 63 can be made flexible so that it can fit into a non-straight conduction hole in the bone fixture. For example, another gripping mechanism can be used that has a release function of grabbing and releasing the plug member.

0031Next, the use of the bone fixture will be described with reference to FIGS. 15 and 16. Figures 15 and 16 show the implantation of a bone fixture with minimally invasive surgery. In step 1), the guide wire 100 is placed percutaneously through the skin 101 at the final position of the bone fixture within the vertebrae 102 of the spinal column. The plug member is not inserted into the bone fixture during this procedure. After that, the bone fixture 2 or the bone fixture pre-combined with the receiving portion 3 and the pressing element 5 as shown in FIG. 15 is supplied, and the guide wire 100 is the second end which is the free end of the bone fixture. Guided from part 9 through the bone fixture and receiving part 3. Next, as shown in step 2), the bone fixation device 1 is guided along the guide wire 100 to the vertebra 102, which is the final implantation site, and is finally screwed into the pedicle. Then shown in step 3) As such, the guide wire is removed.

0032Figures 16a) to 16c) show step 4), which is the process of introducing the plug member. As shown in FIG. 16a), the tool 50 is used to introduce the plug member 30 into the bone fixture 2. FIG. 16b) shows a side view of the bone fixture 2 in a state where the plug member 30 is inserted by the insertion tube 52, and FIG. 16c) shows an enlarged cross-sectional view of a part thereof. The plug member 30 is gripped by the insertion tube 52 of the tool 50, and the insertion tube 52 is inserted into the bone fixture. The plug member 30 is separated from the tool by inserting the guide wire 100 (not shown) and pushing the guide wire 100 into the plug member, and the plug member is finally installed on the shoulder portion 13 to form a bone. Block the fixture. Bone cement or chemicals are then injected and exit through the opening 15 to the surrounding bone material. Bone cement or chemicals do not exit through the second end 9 of the bone fixture because the plug member obstructs the free end second end 9. By doing so, stable fixation can be obtained as a result because there is no leakage from the second end portion 9 of the bone cement that causes loosening of the bone fixture and damage to the vascular structure.

0033In the case of the spherical plug member 40, as long as the plug member 40 is introduced from the upper part of the conduction hole 11, it falls by its own weight and closes the second end portion 9 which is a free end.

0034Another alternative is to grab the plug member 30 or 41 with the needle 63 of a syringe 60 containing bone cement or drug substance and inject bone cement or drug substance into the conduction hole 11 until the free end is occluded. Introduces a plug member.

0035After at least two bone fixtures have been fixed, the rod 4 is inserted and secured by a fixing element.

00361 bone fixing device, 2 bone fixing device, 3 receiving part, 3a 1st end, 3b 2nd end, 4 rod, 5 pressing element, 6 fixing element, 7 axis, 8 head, 9 2nd end , 11 Conduction holes, 12 ends, 13 shoulders, 14 engaging structures, 15 openings, 16 coaxial holes, 16a Ends, 17 recesses, 18a, 18b free legs, 20,21 recesses, 22 coaxial holes, 3 0,40,41 Plug member, 31,33 Cylindrical part, 34 Transition part, 35 Grip part, 42 Recess, 50 Tool, 51 Handle, 52 Insert tube, 53 Open end, 60 Syringe, 61 Handle, 62 plunger, 63 needle or tube, 100 guide wire