KR20080025317A - Bone anchoring device - Google Patents

Abstract

A bone fixing device is provided to perform continuous position setting of a rod by including a smooth surface in the rod. A bone fixing device includes a fixing member(1), a connecting member(9), a recession(3), a sheet(8), and a locking member(10). The fixing member includes a shank(2). The shank is fixed inside bone or spine. The connecting member is elastic for connecting at least two fixing members. The recession receives the connecting member and is connected to the shank for connecting the connecting member with the shank. The sheet is adhered on the bottom of the recession for supporting the connecting member. The locking member is rotatably coupled to the receiver for fixing the connecting member to the sheet. At least one part of a surface of the connecting member inside the recession is smooth and is coupled to a coupling structure of the locking member.

Description

Bone anchoring device

The present invention relates to bone, in particular bone anchors for dynamic stabilization of the spinal column. The bone anchor includes a bone anchor that can be connected with a flexible rod having a smooth surface made of elastic material.

Bone fasteners comprising bone screws and flexible rods made of elastic material are known from EP 1 364 622 A2 and EP 1 527 742 A1. The rod has a corrugated surface, which engages with a rib structure provided on the bottom of the receptacle of the bone screw to form a form-fit connection. The bone holding device according to EP 1 527 742 A1 further comprises a closing member having a rib structure that engages the corrugated surface of the rod. The rod must be correctly inserted into the receptacle to prevent tilting when positioning the corrugated surface of the rod relative to the rib structure. In addition, the position cannot be set continuously. As a result, positioning of the rod relative to the receiving portion is difficult and time wasted.

US 2004/0138660 A1 discloses a locking cap assembly for locking a rigid rod to a receiving body of a bone screw. This locking cap assembly includes locking members inside and outside. The outer locking member is a nut-shaped member, and the inner locking member is rotatably connected to the outer locking member. The side facing the rod of the inner locking member is provided with a ring-shaped variable contact member in contact with the rod. Upon tightening the outer locking member, the deformable member is deformed to provide feedback to the surgeon to determine whether the locking cap assembly has been tightened to the required extent. One example of the variable member is a variable metal ring that is cold welded to the rod.

It is an object of the present invention to provide a bone fixation device which can be used in combination with a flexible rod made of an elastic material and which can provide a convenient and safe locking state.

This object is achieved by a bone fixation device according to claim 1. Further features are described in the dependent claims.

The bone holding device has the advantage that the indirect or dynamic form fit connection between the elastic rod, the receiving portion and the locking member is realized without detracting from the integrity of the rod by the deformation of the rod's elastic material while tightening the locking member. Has

The rod has a smooth surface, allowing for continuous positioning of the rod.

The bone anchor has the advantage that the mass flow along the longitudinal direction of the material of the rod is minimized.

The rod is fixed with a minimum of parts. Therefore, the operation of the bone fixing device is convenient at the time of the procedure, and a reliable fixing state can be obtained.

Further features and advantages of the invention will be more clearly understood from the following detailed description of the embodiments with reference to the accompanying drawings.

As shown in Figures 1 to 4, the bone fixing device according to the first embodiment includes a bone fixing member 1 in the form of a short bone screw. The bone holding member 1 is provided with a shank 2 having bone threads, one end of which is provided with a tip and the other end with a receiving part 3. The receiving portion 3 is substantially cylindrical in shape and comprises a substantially U-shaped recess 4 which forms two legs 5, 6. Both legs are provided with internal threads 7. The bottom of the U-shaped recess forms a sheet 8 for receiving the rod 9. A rod 9 is used to connect the plurality of bone fixation members. A locking member in the form of an internal screw 10 is provided which can be screwed between the two legs 5, 6 to secure the rod 9 to the interior of the recess 4.

As shown in FIGS. 1 and 4, a plurality of rib-shaped protrusions 11 are provided on the surface of the sheet 8. The rib-shaped protrusion 11 extends in a direction perpendicular to the longitudinal axis L of the recess 4, and thus extends in a direction perpendicular to the longitudinal axis L _R of the rod 9. In the embodiment of the figure, the protrusion 11 has a substantially triangular cross section with a rounded tip. The protrusion 11 has a length forming a U-shape corresponding to the sheet 8. The end of the protrusion 11 extends to a position spaced a certain distance from the inner thread 7. Each or a plurality of ribbed protrusions 11 may be formed on one or both sides of the grooved recess providing a depression in the surface of the sheet. Alternatively, one or more depressions may be provided within the surface of the sheet adjacent to one or more protrusions.

The rod 9 is made of elastic flexible biocompatible material, preferably plastic. For example, the rod 9 is made of an elastomer material mainly composed of polycarbonate polyurethane or polycarbonate urethane (PCU). Therefore, the rod is elastically deformed when an external load is applied.

The internal screw 10, which is screwed between the legs 5, 6, comprises a ring-shaped protrusion 12 on the side 10a facing the rod 9. The protrusion 12 has an annular rib shape with an empty center. As shown in Fig. 4, the ring-shaped protrusion 12 has a cross section similar to that of the rib-shaped protrusion 11 of the sheet. When the ring-shaped protrusion 12 is in contact with the rod 9, the ring-shaped protrusion 12 exerts pressure on the rod through the two contact regions 12a and 12b. The diameter of the ring-shaped protrusions 12 is such that the contact areas 12a and 12b on both sides of the rod 9 and the contact areas 11a and 11b of the rib-shaped protrusions and the central axis C of the receiving portion 3 It is formed to a dimension that can be located on parallel vertical lines Va and Vb.

The bone holding member 1 and the inner screw 10 are preferably made of a biocompatible rigid material, preferably a metal such as titanium or a titanium alloy.

During the procedure, at least two bone fixation members 1 are first screwed into adjacent vertebrae, for example cervical vertebral bodies. The rod 9 is then inserted into the receiving portion 3 and seated in the sheet 8. Next, the internal screw 10 is screwed in to lock the rod in position. When the inner screw 10 is not completely engaged, the rod is smooth and its surface is stepless. After adjusting the position of the rod, tighten the inner screw 10 until the ring-shaped protrusion 12 contacts the surface of the rod. As shown in Fig. 4, the contact regions 12a, 12b of the ring-shaped protrusion are pressed downward on the surface of the rod. Likewise, the rib-shaped protrusion 11 is pressed on the surface of the lower side of the rod. The protrusion does not impair the integrity of the surface of the rod. The rod initiates material flow by the applied pressure. As a result of this mass flow an indirect form fit connection is obtained. The rod is held in place by the combination of direct friction and indirect form-fit forces.

The diameter of the ring-shaped protrusion 12 can be equal to or larger than the distance between the rib-shaped protrusions 11.

As shown in FIG. 5A, the engagement structure formed by the protrusion of the sheet and the protrusion of the locking member at the corresponding position on the opposite side of the rod are subjected to a force F acting in the longitudinal direction of the rod 9. Provide a resistive foam fit bond.

As shown in Fig. 5B, the above-described indirect form fit engagement can also be obtained by the other structure of the protrusion of the sheet and the protrusion of the locking member which engages the rod. In this case, however, the resistance to the force F acting in the axial direction of the rod is weak. When the force F is large, the connection state shown in Fig. 5B cannot prevent the waveform movement of the rod, thus weakening the fixed state of the rod.

By using the ring-shaped protrusion of the inner screw, a coupling structure can be provided by the locking member instead of using a filling piece or a pressure member.

6 to 14 show a second embodiment of the bone fixation device. This bone fixation device includes a bone fixation member 20 in the form of a multi-axis bone screw. This bone holding member is provided with the shank 21 provided with the bone thread, The tip of one end of this shank is provided with the spherical head 22 at the other end. The head 22 on the opposite side of the shank is provided with a recess 23 for engaging with the screwing study.

The bone holding member 20 further includes a receiving portion 25 having a first end portion 26 and a second end portion 27 facing the first end portion. The central axis C of this receiving portion penetrates the planes of the first and second ends. A bore coaxial with the central axis C is provided between the first end and the second end. The second end 27 is provided with an opening 30 whose diameter is smaller than the diameter of the bore 29. In the state where the shank penetrates through this opening 30, the head 22 is pivotally supported in the receiving portion 25.

The receiving portion 25 further includes a substantially U-shaped recess 31 extending from the first end 26 toward the second end 27. Two legs 32 and 33 are formed by this U-shaped recess. This leg is provided with an internal thread 34.

A pressure member 35 having a substantially cylindrical structure is provided. The outer diameter of the pressure member is such that the pressure member 35 can be introduced into the bore 29 of the receiving portion and moved along the axial direction.

It has a dimension slightly smaller than the inner diameter of the bore 29.

On the lower side facing the second end 27 of the pressure member 35, a spherical recess 36 having a radius coinciding with the radius of the spherical head 22 of the screw member is included. On the opposite side of the pressure member 35, a U-shaped recess 37 extending in the transverse direction of the central axis C is included. The transverse diameter of this recess is chosen such that the rod 9 received in the receptacle 25 can be inserted into the recess 37 and dimensioned such that it can be transversely guided inside the recess. . The depth of the U-shaped recess 37 is selected so that the legs 37a and 37b extend to the top surface of the rod when the rod is installed inside the U-shaped recess. The depth of the recess 37 is preferably equal to the diameter of the rod 9. The transverse diameter of the recess and / or the depth of the recess 37 in the region of the rib may be slightly larger than the diameter of the rod to allow for local plastic flow of material of the rod.

The bottom 38 of the U-shaped recess of the pressure member 35 forms a sheet of the rod 9. Similar to the first embodiment, a plurality of rib-shaped protrusions 39 are provided on the surface of the sheet 38. In the embodiment of the figure there are two rib-shaped protrusions extending transverse to the longitudinal axis L of the U-shaped recess 37 and thus extending transversely to the longitudinal axis L _R of the rod 9. Is provided. The pressure member also includes a coaxial bore 40 which allows the screwing tool to approach the recess 23 of the head 22.

The locking member is an internal screw 10 having a ring-shaped protrusion 12 on the side facing the rod 9 as in the first embodiment. As shown in FIG. 8, the ring-shaped protrusion 12 has a dimension in which the contact areas 12a and 12b between the ring-shaped protrusion 12 and the rod have a rib-shaped protrusion of the pressure member on the opposite side of the rod. It is selected to be located at a position corresponding to the contact areas 39a and 39b.

The pressure member 35 and the inner screw 10 are formed to have a dimension such that the lower surface 10a of the inner screw can be supported by the upper surfaces 41a and 41b of the legs of the pressure member in an assembled state. The dimensions of the projection 39 of the pressure member and the dimensions of the ring-shaped projection 12 of the internal thread are selected to be dimensions that can be secured by indirect foam fit indentation without compromising the integrity of the surface of the rod.

During the procedure, the bone holding member 20 is assembled in advance. That is, the bone screw is pivotally supported in the receptacle, and the pressure member is lightly supported at the position where the U-shaped recess and the U-shaped recess of the receptacle are aligned. The bone fixation member is screwed into the bone and the angular position of the receptacle with respect to the bone screw is adjusted. The rod 9 is inserted and the internal screw 10 is tightened downward to clamp the rod. This clamping action is the same as that of the first embodiment. When the inner screw is tightened, the inner screw pressurizes the upper surfaces 41a and 41b of the pressure member and the head 22 to fix each position of the head in the receiving portion.

Since the lower side surface 10a of the inner thread is supported on the upper surfaces 41a and 41b of the pressure member, the receiving portion 25 by the mass flow of the elastic rod 9 when the projections 12 and 39 are pressed on the rods. The loosening of the fixed state of the head in) does not occur.

Pressing of the protrusions 39, 12 in the surface of the rod allows secondary adjustment since locking of the rod is achieved without compromising the complete structure of the rod.

Embodiments in which the above-described embodiments are modified are also possible.

The number of rib-shaped protrusions can be changed. Instead of providing only rib-shaped protrusions on the surface of the locking member and sheet, combinations of protrusions and depressions may be provided. Such a structure allows a foam fit connection to be formed by the flow of material into the depression when the protrusion is pressed onto the surface of the rod. The volume of the protrusions and recesses is advantageously the same or the same so that when the mass flow is complete the volume of the rod of the connection of the rod and the receptacle is approximately the same volume as the previous volume.

The protrusions and / or recesses do not necessarily have a ribbed or grooved structure and may have any shape. The protrusion in contact with the surface of the rod may have a shape other than the ring shape. Depending on the external load, at least one tooth shaped to intrude into the surface of the rod must be provided to form an indirect form fit connection between the locking member and the rod or between the sheet and the rod. The ring-shaped protrusion on the locking member is a preferable structure because the locking member can be easily fastened by a rotational movement.

The cross section of the rod does not necessarily have to be a circular cross section, but may be formed into an oval or a square.

In the second embodiment, a cap for closing the bore may be installed after screwing the bone fixing member into the bone to prevent the substance from flowing out through the bore 40 provided in the pressure member.

The locking member can also be retrofitted. For example, the locking member may consist of a nut with an integral coaxial pin. This pin is provided with a protrusion in contact with the surface of the rod. In this case, the leg of the receiving portion is provided with an external thread that engages with the thread of the nut. In the second embodiment described above, the bone holding member is introduced into the receiving portion from the top. However, depending on the structure, the bone fixing member may be introduced from the bottom of the receiving portion.

The head and the shaft of the bone fixing member can be assembled by constructing separate parts.

The present invention is not limited to screws as bone fixation members but can also be embodied as bone hooks or any other bone fixation members.

1 is an exploded perspective view of a first embodiment of a bone fixation device.

2 is an assembly view of the bone fixing device of FIG.

3 is a perspective view of the locking member of the bone fixing device of FIG.

4 is a partial cross-sectional view of the bone fixation device of FIGS. 1 and 2.

Figure 5a is a schematic view of the fixing mechanism of the bone fixing device according to the present invention.

5B is a schematic view of another fastener.

6 is an exploded perspective view of the bone fixing device according to the second embodiment.

7 is an assembled perspective view of the bone fixing device of FIG.

8 is a partial cross-sectional view taken along the axis of the rod of the bone fixation device according to FIG. 7.

9 is a cross-sectional view taken along the line M-M of the bone fixing device of FIG.

Fig. 10 is a sectional view of the locking member of the second embodiment.

11 is a perspective view of the pressure member of the bone fixing device according to the second embodiment.

12 is a plan view of the pressure member shown in FIG.

FIG. 13 is a side view of the pressure member shown in FIG. 11.

14 is a cross-sectional view taken along the line S-S of the pressure member of FIG.

Claims (18)

A fixing member (1; 20) comprising a shank (2; 21) fixed in a bone or spine; A connecting member 9 made of an elastic material for connecting at least two fixing members; A receiving portion (3; 25) connected to said shank for receiving said connecting member and simultaneously connecting said connecting member to said shank; A sheet (8; 38) for the connecting member provided in the receiving portion; An integral locking member 10 rotatably coupled with the receiving portion to fix the connecting member in a sheet, At least a part of the connecting member 9 received in the recess has a substantially smooth surface, The locking member 10 is a bone fixing device having a coupling structure 12 in contact with the surface of the connecting member. 2. A bone fixation device according to claim 1, wherein the sheet (8; 38) comprises a coupling structure (11; 39) in contact with the surface of the connecting member (9). 3. The coupling structure (12) of the locking member (10) and the coupling structure (11; 39) of the sheet (8; 38) are arranged at corresponding positions on both sides of the coupling member. A bone fixer characterized by. 4. The bone according to one of the preceding claims, characterized in that the engagement structure (11; 39) of the sheet (8; 38) is an elongate protrusion extending transverse to the longitudinal direction of the connecting member. Fixture. 5. Receptacle (3; 25) according to one of the preceding claims, having a substantially U-shaped recess (4; 31) forming two legs provided with threads therein. , The locking member (10) is a bone fixing device, characterized in that the inner screw is screwed between the two legs. 6. The bone fixing device according to claim 5, wherein the coupling structure of the locking member (10) is a ring-shaped protrusion (12). 7. The bone fixation device according to any one of claims 1 to 6, wherein the coupling structure comprises a plurality of protrusions. 8. A bone fixation device according to any one of the preceding claims, wherein said coupling structure comprises a plurality of depressions. 9. The receiving device (3) according to one of the preceding claims, wherein the receiving portion (3) has a substantially U-shaped recess (4) forming two legs (6, 7), and the sheet (8). Is provided on the bottom of the recess. 9. The bone holding member (20) of claim 1, wherein the bone holding member (20) is pivotally connected to the receiving portion (25), and the sheet (38) is provided in the pressure member (35). And the pressure member is movable within the receiving portion and simultaneously locks the respective positions of the bone fixing member when pressure is applied to the pressure member. 11. A bone fixation device according to any one of the preceding claims, wherein the connecting member is made of an elastomeric material. 12. A bone fixation device according to any one of the preceding claims, wherein said connecting member is a rod. 13. The bone fixation device according to one of the preceding claims, characterized in that the surface of the connecting member (9) is free of protrusions and / or depressions. 14. The bone lock according to any one of claims 1 to 13, wherein the coupling structure of the locking member is coupled to the surface of the coupling member to form an indirect form fit connection. 14. The bone fixation device according to any one of claims 2 to 13, wherein the coupling structure of the sheet is combined with the connecting member to form an indirect form fit connection. The method of claim 1, wherein the locking of the connecting member in the receiving portion is And a frictional connection comprising a portion of an indirect form fit connection of said locking member and said connecting member. 17. The bone fixation device according to any one of the preceding claims, wherein the connection between the locking member and the receiving member is a screw connection. 18. The bone holding device according to any one of claims 1 to 17, wherein the rod is clamped between the sheet and the locking member, wherein the outer shape of the sheet and the outer shape of the locking member are different from the outer shape of the rod.

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