Bone anchor, and kit having a bone anchor for positioning a reference marker

Abstract

The invention relates to a bone anchor (1) having an anchor body (2) from which a bone-engaging portion (3) extends in the direction of a first free end and which, at a second free end, has a coupling portion (4) for coupling to a reference marker (5). At least one helical blade (6) is present which extends from the anchor body (2) to the first free end and which, in the axial direction of the bone-engaging portion (3), winds about the longitudinal axis (7) of the bone-engaging portion (3) to follow a helical line. The invention further relates to an instrument (26) for introducing and extracting the bone anchor (1), a quick-action coupling (21) for fastening to the bone anchor (1), and a kit (30) comprising the bone anchor (1), the instrument (26), the quick-action coupling (21) and a reference marker (5).

Description

[0001] Bone anchor and ensemble with a bone anchor for positioning a reference marker

[0002] DESCRIPTION:

[0003] The invention relates to a bone anchor having an anchor body from which a bone engagement portion extends toward a first free end and which, at a second free end, has a coupling portion intended for coupling with an additional benefit. At least one helical blade extending from the anchor body to the first free end is present, which helical blade winds in the axial direction of the bone engagement portion around the longitudinal axis of the bone engagement portion, following a helical line. The invention further relates to an instrument for inserting and removing the bone anchor, a quick-release coupling for attachment to the bone anchor, and an assembly comprising the bone anchor, the instrument, the quick-release coupling, and a reference marker.

[0004] Imaging techniques such as computed tomography (CT) with X-rays, magnetic resonance imaging (MRI), positron electron tomography (PET), and ultrasound imaging are used in medicine for diagnostic purposes and are also used to guide a surgeon during an operation and to support them during the surgical procedure by providing up-to-date information that can be provided in real time with high spatial and temporal resolution. Navigation systems are used to ensure correct spatial orientation; these can also record and evaluate patient movements during the operation. These navigation systems include a reference marker that must be positioned on the patient. This should preferably be reversible and detachable, yet still have a stable, stationary connection to avoid data offset.

[0005] WO 2007 / 0389135 A2 discloses a device for positioning a reference marker. A positioning element to be inserted into a bone has a bone-engaging section in which four cutting edges extend radially from a central element at an angle of 90° to each other. A reference frame can be attached to the positioning element inserted into the bone.

[0006] The object of the present invention is to provide a bone anchor that can be securely fixed in the bone with only minor traumatic injuries. Furthermore, the object is to provide an instrumentation for inserting, using, and removing the bone anchor.

[0007] 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 with expedient further developments of the invention are specified in the dependent claims.

[0008] The bone anchor of the type mentioned above is characterized by the fact that the helical blade increases the flexural rigidity of the bone engagement section and provides improved protection against twisting and tilting. All six translational and rotational degrees of freedom of movement are particularly well blocked, which is particularly important when wearing a reference marker, as this improves navigation. The winding of the helical blade around the longitudinal axis of the bone anchor also provides increased pull-out strength. A further advantage for the patient is that when the bone anchor is inserted, only a small defect is created in the resulting cross-sectional area of ​​the bone, characterized by short unidirectional bridging distances. The traumatic load is therefore lower than with screws, where the bridging distance essentially corresponds to the screw diameter.With this invention, the bone only needs to bridge the width of the helical blade during healing. The advantages of the invention are particularly evident when the patient has reduced bone density.

[0009] It is advantageous if the helical blade is present in multiple layers, with an odd number, especially three, being particularly preferred. The odd number of helical blades results in a cross-section with reduced symmetry, which distributes the flexural rigidity more evenly along the longitudinal axis. There is no preferred direction of flexural rigidity, as would be the case with two or four helical blades.

[0010] It is not necessary for a given helical blade to wind completely 360° around its longitudinal axis. Rather, it is sufficient if the rotation of the helical blade on the bone-engaging section covers an arc between 25° and 180° from the anchor body to the first free end. It is particularly preferred if the arc covers between 45° and 120°, and in particular, corresponds to 60°.

[0011] It is advantageous if the blade thickness of the helical blade increases from the first free end in the proximal direction toward the anchor body and / or if the helical blade has a distally tapered helical tip at the first free end in the end region of the bone engagement section. This design facilitates the insertion of the bone anchor into the patient's bone. The helical tip can have a sawtooth profile, which supports the secure positioning of the bone anchor when it is placed on the bone.

[0012] Insertion is also facilitated by the presence of a cannulation, as this is used in conjunction with a guide wire that dictates the placement location. The coupling section features a collar with a distal and proximal recess. This design can be used to couple the bone anchor to an instrument through which impact impulses can be transmitted relative to the bone for insertion or removal of the bone anchor.

[0013] It is also intended that the cross-sectional area of ​​the anchor body increases from the bone engagement section to the annular collar. This allows the bone engagement section to be limited to the size sufficient for a secure fit while simultaneously increasing mechanical stability in the areas through which force is transmitted to the bone anchor for insertion and removal. For this purpose, the distal rear grip can also be assigned a key surface formed on both sides of the longitudinal axis, whereby the associated cross-sectional reduction is at least partially compensated by the previously occurring enlargement.

[0014] To enable the bone anchor placed in the patient's bone to be used, in particular, for attaching a reference marker for navigation, the coupling section has a first sleeve in which a second sleeve is mounted, preloaded by the force of a spring and protruding from the second free end. 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 section enables quick coupling with additional instruments or devices, thus minimizing the time required for this and the stress on the patient.

[0015] The first sleeve is provided with conically running toothed surfaces in its distal region. This design, in conjunction with the second sleeve, enables precise positioning of a quick-action coupling or an additional instrument or device, which ensures precise positioning of the bone anchor with little or no play. The invention also provides an instrument for inserting and removing the bone anchor, wherein two L-shaped strips are provided, the short legs of which have a groove designed to receive the anchor body. These short legs can interact with the rear grips to transmit the required impact impulses, which are applied to the free ends of the long legs, to the bone anchor.

[0016] The invention also relates to a quick-action coupling for attachment to the bone anchor, wherein a rod has a coupling sleeve open at one of its free ends on the front and sides, with conically extending toothed mating surfaces formed in the inner circumference of the sleeve. This quick-action coupling is thus adapted and, in particular, complementary to the coupling section. The rod can also be cannulated and is particularly suitable as a carrier for an additional instrument, a device, or a reference marker.

[0017] The components can also be combined into a single assembly comprising a bone anchor, an instrument, a quick-connect coupling, and a reference marker, whereby the aforementioned advantages and effects also apply to this assembly. A guide wire can be included in the assembly as an additional component, but is also dispensable, as it is often already available.

[0018] The features and feature combinations mentioned above in the description, as well as the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figure, can be used not only in the respective combinations specified, but also in other combinations or on their own, without departing from the scope of the invention. Thus, embodiments are also considered to be encompassed and disclosed by the invention that are not explicitly shown or explained in the figure, but which emerge and can be produced through separate feature combinations from the explained embodiments.

[0019] Further advantages, features, and details of the invention will become apparent from the claims, the following description of preferred embodiments, and the drawings. Herein:

[0020] Figure 1 is a perspective view of a bone anchor,

[0021] Figure 2 is a side view of the bone anchor from Figure 1,

[0022] Figure 3 shows section III - III from Figure 2,

[0023] Figure 4 shows the bone anchor from Figures 1 to 3 with a guide wire inserted into a cannulation,

[0024] Figure 5 shows the bone anchor from Figure 5 with an attached instrument,

[0025] Figure 6 is a perspective view of a quick coupling,

[0026] Figure 7 is a side view of the quick coupling from Figure 6,

[0027] Figure 8 shows section VIII - VIII from Figure 7,

[0028] Figure 9 shows detail IX from Figure 7, and

[0029] Fig. 10 a reference marker connected to the bone anchor via the quick coupling.

[0030] Figure 1 shows a bone anchor 1 with an anchor body 2, from which a bone engagement section 3 extends toward a first free end. At a second free end, the bone anchor 1 has a coupling section 4 intended for coupling to an additional feature, such as a reference marker 5. At least one helical blade 6 is present, extending from the anchor body 2 to the first free end, which winds in the axial direction of the bone engagement section 3 around the longitudinal axis 7 of the bone engagement section 3, following a helical line. In the exemplary embodiment shown, the helical blade 6 is present in multiple, odd numbers, namely three helical blades 6. However, according to exemplary embodiments not shown, the helical blade 6 can be present in a different, even even, number, such as two helical blades 6, four helical blades 6, or five helical blades 6.

[0031] The three helical blades 6 are evenly distributed around the circumference of the bone-engaging section 3, i.e., at an angular spacing of 120°. The helical blades 6 do not have to completely wrap around the bone-engaging section 3 in a 360° arc. The rotation of the three helical blades 6 on the bone-engaging section 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 easily determined by projecting the helical blade 6 into a plane oriented perpendicular to the longitudinal axis 7.

[0032] In Figures 1 and 4 it can be seen that the blade thickness of the helical blade 6 increases from the first free end in the proximal direction towards the anchor body 2, and that the helical blade 6 has a distally tapered helical tip 8 with a sawtooth profile 9 at the first free end in the end region of the bone engagement section 3.

[0033] Figure 4 also shows that a cannulation 10 is present in the bone anchor 1, through which a guide wire 11 can be inserted.

[0034] The coupling section 4 has an annular collar 12, to which a rear grip 13 is assigned both distally and proximally. A key surface 14 formed on both sides of the longitudinal axis is assigned to the distal rear grip 13, which can also be replaced or supplemented by a circumferential groove. The cross-sectional area of ​​the anchor body 2 increases from the bone engagement section 3 to the annular collar 12.

[0035] Figures 1 to 3 also serve to further explain the coupling section 4, which has a first sleeve 15 in which a second sleeve 17 is mounted, preloaded by the force of a spring 16 and protruding from the second free end. The first sleeve 15 has a lateral opening 18, which is used to insert 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 spring-loaded second sleeve 17 is securely received. In the embodiment shown, the second sleeve 17 has a conical shape 19 at its free end.

[0036] The coupling section 4 is further designed such that the first sleeve 15 has conically extending toothed surfaces 20 in its distal region, which enable better positioning of a complementary coupling element, such as a quick-action coupling 21, for attachment to the bone anchor 1. The quick-action coupling 21 shown in Figures 6 to 9 comprises a cannulated rod 22, which has, at one of its free ends, a coupling sleeve 23 open at the front and sides, in the inner circumference of which conically extending toothed counter surfaces 24 are formed. A conical receptacle 25 is formed opposite the toothed counter surfaces 24.

[0037] Figure 5 shows an instrument 26 for inserting and removing the bone anchor 1, wherein two L-shaped strips 27 are provided, the short legs 28 of which have a groove 29 intended for receiving the anchor body 2. Figure 5 also shows that when the instrument 26 is used, the short legs 28 interact with the rear grips 13 and introduce impact impulses via the annular collar 12 into the anchor body 2. For the sake of clarity, impact surfaces for absorbing hammer blows are not separately shown.

[0038] Figure 10 shows an assembly 30 comprising a bone anchor 1, a quick-coupling device 21, and a reference marker 5, which can be supplemented by the instrument 26 according to Figure 5 and optionally by a guide wire 11. Figure 10 shows the completed state, without the patient's bone, how the bone anchor 1 carries a reference marker 5 via the quick-coupling device 21. A use of the assembly 30 will be briefly described below as an example.

[0039] In preparation for a diagnosis using an imaging procedure or for an operation, a guide wire 11 can first be placed on a bone using the tip formed on the guide wire 11, over which the bone anchor 1 is then pushed and guided to the bone until the helical tips 8 with the sawtooth profile 9 rest there. The instrument 26 can then be attached with its short legs 28 to the rear handles 13 in order to subsequently apply blows to the free end of the instrument 26, by means of which the bone anchor 1 with the bone engagement section 3 is driven into the bone. As a result of the winding of the helical blades 6, a slight rotation of the bone anchor 1 occurs, which contributes to its secure fit in the bone.Once the bone anchor 1 is placed in the bone, the instrument 26 is removed and the quick coupling 21 is attached to the coupling section 4, which can be done without tools due to the design of the quick coupling 21. The quick coupling 21 is rotationally stable due to the conical toothed counter surfaces 24 and axially fixed due to the spring-loaded second sleeve 17. The reference marker 5 can then be attached to the rod 22 for its intended use.

[0040] After use, the reference marker 5 and the quick coupling 21 are removed and the instrument 26 is remounted in order to drive the bone anchor 1 out of the bone by impact.

[0041] The wound in the bone then heals relatively quickly due to the minor injuries.

[0042] 1 bone anchor

[0043] 2 anchor bodies

[0044] 3 Bone intervention section

[0045] 4 Coupling section

[0046] 5 reference markers

[0047] 6 Helix blade

[0048] 7 Longitudinal axis

[0049] 8 Helix tip

[0050] 9 sawtooth profile

[0051] 10 Cannulation

[0052] 11 Guide wire

[0053] 12 ring bundle

[0054] 13 Rear grip

[0055] 14 key surface

[0056] 15 first sleeve

[0057] 16 spring

[0058] 17 second sleeve

[0059] 18 side opening

[0060] 19 conical shape

[0061] 20 tooth surfaces

[0062] 21 Quick coupling

[0063] 22 staff

[0064] 23 Coupling sleeve

[0065] 24 toothing counter surfaces

[0066] 25 cone holder

[0067] 26 instruments

[0068] 27 L-shaped strips

[0069] 28 short leg

[0070] 29 grooves

[0071] 30 Ensemble

Claims

CLAIMS:

1. Bone anchor (1) with an anchor body (2), from which a bone engagement section (3) extends in the direction of a first free end and which has a coupling section (4) intended for coupling with an additional benefit at a second free end, characterized in that at least one helical blade (6) extending from the anchor body (2) to the first free end is present, which winds in the axial direction of the bone engagement section (3) around the longitudinal axis (7) of the bone engagement section (3) following a helical line.

2. Bone anchor (1) according to claim 1, characterized in that the helical blade (6) is present multiple times.

3. Bone anchor (1) according to claim 1 or 2, characterized in that the rotation of the helical blade (6) on the bone engagement 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. Bone anchor (1) according to one of claims 1 to 3, characterized in that the blade thickness of the helical blade (6) increases from the first free end in the proximal direction to the anchor body (2) and / or that the helical blade (6) has a distally tapered helical tip (8) at the first free end in the end region of the bone engagement section (3).

5. Bone anchor (1) according to claim 4, characterized in that the helical tip (8) has a sawtooth profile (9).

6. Bone anchor (1) according to one of claims 1 to 5, characterized in that a cannulation (10) is present.

7. Bone anchor (1) according to one of claims 1 to 6, characterized in that the coupling section (4) has an annular collar (12) to which a rear grip (13) is assigned both distally and proximally.

8. Bone anchor (1) according to claim 7, characterized in that the cross-sectional area of ​​the anchor body (2) increases from the bone engagement section (3) to the annular collar (12).

9. Bone anchor (1) according to claim 7 or 8, characterized in that the distal rear grip (13) is assigned a key surface (14) formed on both sides of the longitudinal axis (7).

10. Bone anchor (1) according to one of claims 1 to 9, characterized in that the coupling section (4) 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 the second free end.

11. Bone anchor (1) according to claim 10, characterized in that the first sleeve (15) has a lateral opening (18).

12. Bone anchor (1) according to claim 10 or 11, characterized in that the first sleeve (15) has conically extending toothed surfaces (20) in its distal region.

13. Instrument (26) for inserting and removing the bone anchor (1) according to one of claims 1 to 12, characterized in that two L-shaped strips (27) are provided, the short legs (28) of which have a groove (29) intended to receive the anchor body (2).

14. Quick coupling (21) for attachment to the bone anchor (1) according to one of claims 10 to 12, characterized in that a rod (22) has at one of its free ends a coupling sleeve (23) which is open at the front and at the side and in the inner circumference of which conically running toothed counter surfaces (24) are formed.

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

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