Bone anchor and assembly with bone anchor for positioning reference marker

Abstract

The invention relates to a bone anchor (1) having an anchor body (2) from which a bone joint (3) extends in the direction of a first free end and which has a coupling (4) at a second free end, said coupling being intended to be coupled to a reference marker (5). There is at least one helical blade (6) extending from the anchor body (2) to the first free end, which helical blade is wound around a longitudinal axis (7) of the bone junction (3) in the axial direction of the bone junction (3) with a helical line. The invention also relates to an instrument (26) for introducing and removing said bone anchor (1), to a quick coupling (21) for fastening to said bone anchor (1) and to an assembly (30) comprising said bone anchor (1), said instrument (26), said quick coupling (21) and a reference marker (5).

Description

Technical Field

[0001] The invention relates to a bone anchor having an anchor body, a bone engaging portion extending from the anchor body in the direction of a first free end, and a coupling portion at a second free end, the coupling portion being designed for coupling with an accessory. There is at least one spiral blade extending from the anchor body to the first free end, the spiral blade being wound around a longitudinal axis of the bone engaging portion following a spiral line in the axial direction of the bone engaging portion. The invention also relates to an instrument for introducing and removing the bone anchor, a quick coupler for fastening at the bone anchor, and an assembly comprising the bone anchor, the instrument, the quick coupler, and a reference marker. Background Art

[0002] In the medical field, imaging methods such as X-ray computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET) and ultrasound imaging are used for diagnostic purposes and are also used to guide the surgeon during surgery and to assist during surgical interventions with current information that can be provided in real time with high spatial and temporal resolution. For exact spatial orientation, navigation systems are also used, with which the patient's movements can also be detected and analyzed during surgery. These navigation systems include reference markers that need to be positioned on the patient, more precisely preferably reversibly and releasably in a still stable, stationary connection, in order to avoid data drift.

[0003] A device for positioning reference markers is known from WO 2007 / 0389135 A2, in which a positioning element to be introduced into the bone has a bone joint, wherein four blades radially extend from a central element at an angle of 90° to one another. A reference frame can be fastened to the positioning element introduced into the bone. Summary of the invention

[0004] The object of the present invention is to provide a bone anchor which can be securely fastened in the bone with only minimal traumatic injury. It is also an object to provide an instrument for introducing, utilizing and removing the bone anchor.

[0005] This object is achieved by a bone anchor having the features of claim 1, by an instrument having the features of claim 13, by a quick coupling having the features of claim 14 and by an assembly having the features of claim 15. Advantageous embodiments of the invention with expedient developments are given in the dependent claims.

[0006] The bone anchor of the type described at the outset is unique in that, on the one hand, the bending stiffness of the bone joint is increased by the spiral blade, and on the other hand, there is an improved safety against twisting and turning. All six degrees of freedom of translational and rotational movement are particularly well blocked, which is particularly important in the case of bearing reference markers, as this improves navigation. Due to the winding of the spiral blade around the longitudinal axis of the bone anchor, there is also an increased pull-out strength. For the patient, the following advantages also arise: when the bone anchor is introduced, only a small defect occurs at the cross section generated in the bone, which is characterized by a shorter one-way span. Therefore, the traumatic burden is less compared to screws, wherein the span essentially corresponds to the screw diameter. In the present invention, the bone only needs to span the width of the spiral blade during healing. The advantages of the present invention are particularly evident when there is a reduced bone density in the patient.

[0007] Advantageously, there are a plurality of said spiral blades, wherein an odd number, in particular three spiral blades, is particularly preferred. An odd number of spiral blades results in a cross section with reduced symmetry, whereby the bending stiffness is more evenly distributed along the longitudinal axis. The bending stiffness has no preferential direction as would be possible with two or four spiral blades.

[0008] There is no need for a given spiral blade to completely wrap around the longitudinal axis through 360°. Instead, it is sufficient for the spiral blade to cover an arc of between 25° and 180° from the rotation of the anchor body to the first free end on the bone engagement portion. It is particularly preferred to cover an arc of between 45° and 120°, and in particular corresponds to an arc of 60°.

[0009] Advantageously, the blade thickness of the spiral blade increases from the first free end in the proximal direction toward the anchor body and / or the spiral blade has a spiral tip that tapers and converges distally at the first free end in the end region of the bone joint. This configuration makes it easier to introduce the bone anchor into the patient's bone. In this case, the spiral tip can have a sawtooth profile that assists in fixing the position when the bone anchor is plugged into the bone.

[0010] The presence of a cannula also makes introduction easier as it is used in conjunction with a guide wire at a predetermined placement location.

[0011] The coupling portion has an annular flange which is associated with the rear grip portion both distally and proximally.This configuration can be used to couple the bone anchor to an instrument through which a percussive impulse for introducing or removing the bone anchor relative to the bone can be conducted.

[0012] It is also proposed that the cross-sectional area of ​​the anchor body increases from the bone engaging portion to the annular flange. This makes it possible to limit the bone engaging portion to a size that is sufficient for a fixed placement and at the same time increases the mechanical stability in the region for transmitting forces to the bone anchor for introduction and removal. For this purpose, it is also possible to associate a distal rear grip with keyway surfaces formed on both sides of the longitudinal axis, wherein the associated cross-sectional reduction is at least partially compensated by the previously performed increase.

[0013] In order to use the bone anchor placed in the patient's bone, in particular for fastening reference markers for navigation, the coupling has a first sleeve, in which a second sleeve, which is preloaded by the force of a spring and extends from the second free end, is mounted, wherein the first sleeve has a lateral opening. The spring and the second sleeve can be mounted through the lateral opening. The design of the coupling allows for a quick coupling with additional instruments or devices, thereby minimizing the duration of the coupling and the burden on the patient.

[0014] It is proposed that the first sleeve has a conically extending engagement surface in its distal region. This configuration in cooperation with the second sleeve allows for accurate position fixation of a quick coupler or an additional instrument or device, which maintains accurate positioning of the bone anchor without play or with only a small amount of play.

[0015] The invention also provides an instrument for introducing and removing the bone anchor, wherein two L-shaped strips are provided, whose short sides have recesses which are designed to receive the anchor body. These short sides can cooperate with the rear grip to transmit the necessary impact impulses applied to the free ends of the long sides to the bone anchor.

[0016] The invention also provides a quick coupler for fastening to the bone anchor, wherein the rod has at its free end a coupling sleeve open at the end and laterally, in the inner circumference of which a conically extending mating surface is formed. Such a quick coupler is formed to fit the coupling and in particular to complement it, wherein the rod can also be cannulated and is particularly suitable as a holder for additional instruments, devices or reference markers.

[0017] These components can also be assembled into an assembly comprising a bone anchor, an instrument, a quick coupler and a reference marker, wherein the above-mentioned advantages and effects also apply to such an assembly. Supplementarily, a guide wire can be received in the assembly, but this is not necessary, since a guide wire is usually already provided.

[0018] Without departing from the framework of the present invention, the features and feature combinations mentioned above in the description and the features and feature combinations mentioned below in the description of the figures and / or shown separately in the figures can be used not only in the respectively given combination, but also in other combinations or alone. Therefore, embodiments not explicitly shown or explained in the figures can also be regarded as being included and disclosed by the present invention, but emerge from the described embodiments and can be produced by individual feature combinations. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Further advantages, features and details of the invention are apparent from the claims, from the following description of preferred embodiments and with the aid of the drawings. In the drawings:

[0020] Figure 1 A perspective view showing a bone anchor,

[0021] Figure 2 Shown from Figure 1 Side view of the bone anchor.

[0022] Figure 3 Shown from Figure 2 Section III-III,

[0023] Figure 4 Shown from Figures 1 to 3 A bone anchor having a guide wire inserted into a cannula,

[0024] Figure 5 Shown from Figure 5 A bone anchor having an attached instrument,

[0025] Figure 6 A perspective view showing a quick coupler,

[0026] Figure 7 Shown from Figure 6 Side view of a quick coupler,

[0027] Figure 8 Shown from Figure 7 Section VIII-VIII,

[0028] Fig. 9 Show Figure 7 Details of IX, and

[0029] Fig.10 The reference marker is shown connected to the bone anchor via a quick coupler. DETAILED DESCRIPTION

[0030] Figure 1A bone anchor 1 is shown with an anchor body 2, from which a bone engaging portion 3 extends in the direction of a first free end. At a second end, the bone anchor 1 has a coupling portion 4, which is intended for coupling with an accessory, such as a reference marker 5. There is at least one spiral blade 6 extending from the anchor body 2 to the first free end, which spiral blade is wound around a longitudinal axis 7 of the bone engaging portion 3 in the axial direction of the bone engaging portion 3 following a spiral line. In the embodiment shown, there are an odd number of spiral blades 6, more precisely three spiral blades 6. According to embodiments not shown, however, the spiral blades 6 may be present in a different number, i.e. also in an even number, for example 2 spiral blades 6 or 4 spiral blades 6 or 5 spiral blades 6.

[0031] The three spiral blades 6 are evenly distributed around the periphery of the bone joint 3, i.e. at an angular interval of 120°. Here, the spiral blades 6 do not have to completely coil around the bone joint 3 over an arc of 360°. The rotation of the three spiral blades 6 on the bone joint 3 from the anchor body 2 to the first free end can cover an arc between 25° and 180°, preferably between 45° and 120° and in particular 60°. The size of the arc can be simply determined by means of the projection of the spiral blades 6 in a plane oriented perpendicularly to the longitudinal axis 7.

[0032] exist Figures 1 to 4 It can be seen that the blade thickness of the spiral blade 6 increases from the first free end in the proximal direction toward the anchor body 2 and that the spiral blade 6 has at the first free end a spiral tip 8 with a sawtooth profile 9 that tapers and converges distally in the end region of the bone joint 3 .

[0033] Figure 4 It is also shown that a cannula 10 is present in the bone anchor 1 , into which a guide wire 11 can be pushed.

[0034] The coupling portion 4 has an annular flange 12, which is associated with a rear grip 13 both distally and proximally, wherein the distal rear grip 13 is associated with a keyway surface 14 formed on both sides of the longitudinal axis, which keyway surface can also be replaced or supplemented by a surrounding groove. The cross-sectional area of ​​the anchor body 2 increases from the bone engaging portion 3 to the annular flange 12.

[0035] Figures 1 to 3The coupling 4 is also explained in detail, which has a first sleeve 15, in which a second sleeve 17 is mounted, which is prestressed by the force of a spring 16 and projects from a second free end. The first sleeve 15 has a lateral opening 18, which is used to introduce the spring 16 and the second sleeve 17 into the first sleeve 15. The spring travel is shorter than the guide travel, so that the second sleeve 17 prestressed by the spring is received in a captive manner. In the embodiment shown, the second sleeve 17 has a conical structure 19 at its free end.

[0036] The coupling part 4 is further designed so that the first sleeve 15 has a conically extending engagement surface 20 in its distal region, which can achieve better position fixation of a complementary coupling element (such as a quick connector 21) for fastening to the bone anchor 1. For this purpose, Figures 6 to 9 The quick coupling 21 shown in FIG. 2 comprises a rod 22 which has at its free end a coupling sleeve 23 which is open at the end and at the sides and in which a conically extending mating surface 24 is formed in its inner circumference. Opposite to the mating surface 24, a conical receiving portion 25 is formed.

[0037] Figure 5 An instrument 26 for introducing and removing a bone anchor 1 is shown, wherein there are two L-shaped strips 27, whose short sides 28 have recesses 29 which are defined for receiving the anchor body 2. Figure 5 It can also be seen that when the instrument 26 is used, the short side 28 cooperates with the rear grip 13 and directs the striking impulse into the anchor body 2 via the annular flange 12. For the sake of simplicity, the striking surface for receiving the hammer blow is not explicitly shown.

[0038] exist Fig.10 The assembly 30 is shown in FIG. 1 , and the assembly includes a bone anchor 1, a quick connector 21 and a reference marker 5, and can also be connected according to Figure 5 The assembly is supplemented by an instrument 26 and optionally by a guide wire 11. Fig.10 The finished state without the patient's bone is shown here, as the bone anchor 1 carries the reference marker 5 by means of the quick coupling 21 .

[0039] The following is a brief explanation of the usage of the component 30.

[0040] In order to prepare for a diagnosis with imaging methods or for an operation, the guide wire 11 can first be placed on the bone using the tip formed on the guide wire 11, and then the bone anchor 1 can be suspended by the guide wire and guided to the bone until the spiral tip 8 with the sawtooth profile 9 is in contact there. Then the instrument 26 can be plugged into the rear grip 13 with its short side 28 so that a blow is then applied to the free end of the instrument 26, which drives the bone anchor 1 with the bone joint 3 into the bone. Due to the winding of the spiral blade 6, the bone anchor 1 can be easily rotated here, which helps to firmly place it in the bone. If the bone anchor 1 has already been placed in the bone, the instrument 26 is removed and the quick connector 21 is fastened to the coupling 4, which can be done without tools due to the design of the quick connector 21. The quick connector 21 is here arranged in a rotationally stable manner by means of a conical mating surface 24 and in an axially fixed manner due to the second sleeve 17 preloaded by a spring. The reference marker 5 can then be fastened to the rod 22 so that it can be used as intended.

[0041] After use, the reference marker 5 and the quick coupling 21 are removed again and the instrument 26 is reinstalled in order to withdraw the bone anchor 1 from the bone by means of impact.

[0042] Then, because only a small injury was caused, the wound in the bone heals relatively quickly.

[0043] Reference numerals

[0044] 1 Bone Anchor

[0045] 2 Anchor body

[0046] 3 Bone joint

[0047] 4 Connection

[0048] 5 Reference markers

[0049] 6 Spiral Blade

[0050] 7 Longitudinal axis

[0051] 8 Spiral tip

[0052] 9. Jagged Profile

[0053] 10 Intubation

[0054] 11 Guidewire

[0055] 12 Annular flange

[0056] 13 Rear grip

[0057] 14 Keyway surface

[0058] 15 First sleeve

[0059] 16 Spring

[0060] 17 Second sleeve

[0061] 18 Side opening

[0062] 19 Conical structure

[0063] 20 Mating surface

[0064] 21 Quick coupler

[0065] 22 shots

[0066] 23 Connecting sleeve

[0067] 24 Mating surface

[0068] 25 Conical receiving portion

[0069] 26 Instruments

[0070] 27 L-shaped bar

[0071] 28 Short side

[0072] 29 grooves

[0073] 30 Components

Claims

1. A bone anchor (1), comprising an anchor body (2), a bone engaging portion (3) extending from the anchor body in a direction toward a first free end, and the anchor body having a coupling portion (4) at a second free end, the coupling portion being designed to be coupled to an accessory, It is characterized in that There is at least one helical blade (6) extending from the anchor body (2) to the first free end, the helical blade winding in the axial direction of the bone engaging part (3) following a helical line around the longitudinal axis (7) of the bone engaging part (3).

2. The bone anchor (1) according to claim 1, It is characterized in that There are a plurality of said spiral blades (6).

3. The bone anchor (1) according to claim 1 or 2, It is characterized in that The rotation of the helical blade (6) on the bone engaging portion (3) from the anchor body (2) to the first free end covers an arc between 25° and 180° and preferably between 45° and 120°.

4. The bone anchor (1) according to any one of claims 1 to 3, It is characterized in that The blade thickness of the helical blade (6) increases from the first free end in the proximal direction toward the anchor body (2) and / or the helical blade (6) has a distally tapering and converging helical tip (8) at the first free end in the end region of the bone engaging part (3).

5. The bone anchor (1) according to claim 4, It is characterized in that The spiral tip (8) has a sawtooth profile (9).

6. The bone anchor (1) according to any one of claims 1 to 5, It is characterized in that A cannula (10) is present.

7. The bone anchor (1) according to any one of claims 1 to 6, It is characterized in that The coupling portion (4) has an annular flange (12) which is associated with the rear grip portion (13) both distally and proximally.

8. The bone anchor (1) according to claim 7, It is characterized in that The cross-sectional area of ​​the anchor body (2) increases from the bone engaging portion (3) toward the annular flange (12).

9. The bone anchor (1) according to claim 7 or 8, It is characterized in that The distal rear grip portion (13) is associated with keyway surfaces (14) formed on both sides of the longitudinal axis (7).

10. The bone anchor (1) according to any one of claims 1 to 9, It is characterized in that The coupling part (4) comprises a first sleeve (15) in which a second sleeve (17) is installed, which is preloaded by the force of a spring (16) and projects from the second free end.

11. The bone anchor (1) according to claim 10, It is characterized in that The first sleeve (15) has a lateral opening (18).

12. The bone anchor (1) according to claim 10 or 11, It is characterized in that The first sleeve (15) has a conically extending engagement surface (20) in its distal region.

13. An instrument (26) for introducing and removing a bone anchor (1) according to any one of claims 1 to 12, It is characterized in that There are two L-shaped strips (27) whose short sides (28) have recesses (29) defined for receiving the anchor body (2).

14. A quick connector (21) for fastening to a bone anchor (1) according to any one of claims 10 to 12, It is characterized in that The rod (22) has at its free end a coupling sleeve (23) which is open at the end and laterally and in whose inner circumference a conically extending engagement mating surface (24) is formed.

15. An assembly (30) comprising a bone anchor (1) according to one of claims 1 to 12, an instrument (26) according to claim 13, a quick coupler (21) according to claim 14, and a reference marker (5).

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