DE102023109303A1 - Bone anchor and ensemble with a bone anchor for positioning a reference marker - Google Patents

Abstract

The invention relates to a 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 to a reference marker (5) at a second free end. There is at least one helical blade (6) 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. The invention further relates to an instrument (26) for introducing and removing the bone anchor (1), a quick coupling (21) for fastening to the bone anchor (1) and an ensemble (30) comprising the bone anchor (1), the instrument (26), the quick coupling (21) and a reference marker (5).

Description

The invention relates to a bone anchor with an anchor body from which a bone engagement section extends in the direction of a first free end and which has a coupling section at a second free end intended for coupling with an additional benefit. There is at least one helical blade extending from the anchor body to the first free end, which winds in the axial direction of the bone engagement section around the longitudinal axis of the bone engagement section following a helical line. The invention further relates to an instrument for introducing and removing the bone anchor, a quick coupling for fastening to the bone anchor and an ensemble comprising the bone anchor, the instrument, the quick coupling and a reference marker.

Imaging techniques such as computer tomography (CT) with X-rays, magnetic resonance imaging (MRI), positron electron tomography (PET) and ultrasound imaging are used in the medical field for diagnostic purposes and are also used to guide a surgeon during an operation and to support them during the surgical procedure with current information that can be provided in real time with high spatial and temporal resolution. Navigation systems are used to ensure correct spatial orientation, which can also record and evaluate the patient's movements during the operation. These navigation systems include a reference marker that must be positioned on the patient, preferably in a reversible, detachable, but stable, stationary connection to avoid data offset.

From the WO 2007/0389135 A2 A device for positioning a reference marker is known in which a positioning element to be introduced into a bone has a bone engagement section in which four cutting edges project radially from a central element at an angle of 90° to one another. A reference frame can be attached to the positioning element introduced into the bone.

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. A further object is to provide an instrumentation for inserting, using and removing the bone anchor.

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 ensemble having the features of claim 15. Advantageous embodiments with expedient further developments of the invention are specified in the dependent claims.

The bone anchor of the type mentioned at the beginning is characterized by the fact that the helical blade increases the flexural rigidity of the bone engagement section on the one hand and provides improved protection against twisting and tilting on the other. All 6 translational and rotational degrees of freedom of movement are blocked particularly well, which is particularly important when wearing a reference marker, as this improves navigation. There is also increased pull-out strength as a result of the winding of the helical blade around the longitudinal axis of the bone anchor. For the patient, there is also the advantage that only a small defect is created in the bone on the resulting cross-sectional area when the bone anchor is inserted, which defect is 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 the invention, the bone only has to bridge the width of the helical blade when healing. The advantages of the invention are particularly evident when the patient has reduced bone density.

It is advantageous if the helical blade is present in multiples, whereby an odd number, in particular three helical blades, is particularly preferred. The odd number of helical blades leads to a cross-section with reduced symmetry, through which the bending stiffness is distributed more evenly along the longitudinal axis. There is no preferred direction of the bending stiffness, as would be the case with two or four helical blades.

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

It is advantageous if the blade thickness of the helical blade increases from the first free end in the proximal direction to the anchor body and/or that the helical blade at the first free end in the The end area of the bone engagement section has a distally tapered helix tip. This design makes it easier to insert the bone anchor into the patient's bone. The helix tip can have a sawtooth profile that helps secure the position when the bone anchor is placed on the bone.

The insertion is also facilitated if a cannulation is present, as these are used in conjunction with a guide wire that dictates the location of the placement.

The coupling section has a ring collar with a rear handle assigned both distally and proximally. This design can be used to couple the bone anchor to an instrument through which impact impulses for inserting or removing the bone anchor can be transmitted relative to the bone.

It is also intended that the cross-sectional area of the anchor body increases from the bone engagement section to the ring collar. This makes it possible to limit the bone engagement section to the size that is sufficient for a firm fit and at the same time to increase the mechanical stability in the areas through which force is transferred 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 reduction in cross-section is at least partially compensated by the previously made enlargement.

In order to be able to use the bone anchor placed in the patient's bone, in particular for attaching a reference marker for navigation, the coupling section has a first sleeve in which a second sleeve is mounted, pre-tensioned by the force of a spring and protruding from the second free end, the first sleeve having a side opening. The spring and the second sleeve can be mounted through the side opening. The design of the coupling section enables quick coupling with additional instruments or devices, so that the time required for this and the strain on the patient are minimized.

The first sleeve is designed to have conical toothed surfaces in its distal area. This design, in conjunction with the second sleeve, allows a quick coupling or an additional instrument or device to be precisely positioned, which ensures the 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 there are two L-shaped strips, the short legs of which have a groove intended for receiving the anchor body. These short legs can interact with the rear handles in order to transfer the required impact impulses, which are applied to the free ends of the long legs, to the bone anchor.

The invention also relates to a quick coupling for attachment to the bone anchor, wherein a rod has a coupling sleeve that is open at the front and sides at one of its free ends, in the inner circumference of which conical toothing counter surfaces are formed. This quick coupling is thus adapted and in particular designed to complement the coupling section, wherein the rod can also be cannulated and is particularly suitable as a carrier for an additional instrument, a device or a reference marker.

The components can also be combined in an ensemble comprising a bone anchor, an instrument, a quick coupling and a reference marker, whereby the advantages and effects mentioned above also apply to this ensemble. A guide wire can be included in the ensemble as an additional component, but is also dispensable, as this is often already available.

The features and combinations of features mentioned above in the description as well as the features and combinations of features mentioned below in the description of the figures and/or shown in the figure alone can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the invention. Thus, embodiments are also to be regarded as being included and disclosed by the invention that are not explicitly shown or explained in the figure, but which emerge from the explained embodiments and can be produced by separate combinations of features.

• 1 eine perspektivische Darstellung eines Knochenankers,
• 2 eine Seitenansicht des Knochenankers aus 1,
• 3 den Schnitt III - III aus 2,
• 4 den Knochenanker aus den 1 bis 3 mit einem in eine Kanülierung eingesetzten Führungsdraht,
• 5 den Knochenanker aus 5 mit einem angesetzten Instrument,
• 6 eine perspektivische Darstellung einer Schnellkupplung,
• 7 eine Seitenansicht der Schnellkupplung aus 6,
• 8 den Schnitt VIII - VIII aus 7,
• 9 das Detail IX aus 7, und
• 10 einen über die Schnellkupplung mit dem Knochenanker verbundenen Referenzmarker.

Further advantages, features and details of the invention emerge from the claims, the following description of preferred embodiments, and from the drawing. In this figure:

• 1 a perspective view of a bone anchor,
• 2 a side view of the bone anchor 1 ,
• 3 section III - III 2 ,
• 4 the bone anchor from the 1 to 3 with a guide wire inserted into a cannulation,
• 5 the bone anchor 5 with an attached instrument,
• 6 a perspective view of a quick coupling,
• 7 a side view of the quick coupling 6 ,
• 8 the section VIII - VIII from 7 ,
• 9 the detail IX from 7 , and
• 10 a reference marker connected to the bone anchor via the quick coupling.

The 1 shows a bone anchor 1 with an anchor body 2, from which a bone engagement section 3 extends in the direction of a first free end. At a second free end, the bone anchor 1 has a coupling section 4 intended for coupling with an additional benefit such as a reference marker 5. There is at least one helical blade 6 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 multiple times, in an odd number, namely in a number of 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 2 helical blades 6 or 4 helical blades 6 or 5 helical blades 6.

The three helical blades 6 are evenly distributed around the circumference of the bone engagement section 3, i.e. at an angular distance of 120°. The helical blades 6 do not have to completely wrap around the bone engagement section 3 in an arc of 360°. The rotation of the three helical blades 6 on the bone engagement section 3 from the anchor body 2 to the first free end can cover an arc between 25° and 180°, which is 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.

In the 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 tapering helical tip 8 with a sawtooth profile 9 at the first free end in the end region of the bone engagement section 3.

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

The coupling section 4 has an annular collar 12, to which a rear grip 13 is assigned both distally and proximally, wherein the distal rear grip 13 is assigned a key surface 14 formed on both sides of the longitudinal axis, 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.

The 1 to 3 also serve to explain the coupling section 4 in more detail, which has a first sleeve 15 in which a second sleeve 17 is mounted, pre-tensioned 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 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 spring-tensioned second sleeve 17 is held securely. In the embodiment shown, the second sleeve 17 has a conical shape 19 at its free end.

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

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

In the 10 an ensemble 30 comprising a bone anchor 1, a quick coupling 21 and a reference marker 5 is shown, which by Instrument 26 pursuant to 5 and can optionally be supplemented by a guide wire 11. The 10 shows the completed state, without the bone of a patient, how the bone anchor 1 carries a reference marker 5 via the quick coupling 21.

In the following, a use of Ensemble 30 will be briefly described as an example.

In preparation for a diagnosis using an imaging procedure or 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, the bone anchor 1 rotates slightly, which contributes to its firm 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 fastened 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 is 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.

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.

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

REFERENCE SYMBOL LIST:

1

bone anchor

2

anchor body

3

bone intervention section

4

coupling section

5

reference marker

6

Helix blade

7

longitudinal axis

8

helix tip

9

sawtooth profile

10

cannulation

11

guide wire

12

ring band

13

rear grip

14

key area

15

first sleeve

16

Feather

17

second sleeve

18

side opening

19

conical shape

20

tooth surfaces

21

quick coupling

22

rod

23

coupling sleeve

24

gear mating surfaces

25

cone mount

26

instrument

27

L-shaped strips

28

short leg

29

Nut

30

ensemble

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2007/0389135 A2 [0003]

Claims (15)

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. Bone anchor (1) after claim 1 , characterized in that the helical blade (6) is present multiple times. Bone anchor (1) after claim 1 or 2 , 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°. Bone anchor (1) according to one of the Claims 1 until 3 , characterized in 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/or that the helical blade (6) has a distally tapering helical tip (8) at the first free end in the end region of the bone engagement section (3). Bone anchor (1) after claim 4 , characterized in that the helical tip (8) has a sawtooth profile (9). Bone anchor (1) according to one of the Claims 1 until 5 , characterized in that a cannulation (10) is present. Bone anchor (1) according to one of the Claims 1 until 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. Bone anchor (1) after claim 7 , characterized in that the cross-sectional area of the anchor body (2) increases from the bone engagement portion (3) to the annular collar (12). Bone anchor (1) after 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). Bone anchor (1) according to one of the Claims 1 until 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. Bone anchor (1) after claim 10 , characterized in that the first sleeve (15) has a lateral opening (18). Bone anchor (1) after claim 10 or 11 , characterized in that the first sleeve (15) has conically extending toothing surfaces (20) in its distal region. Instrument (26) for inserting and removing the bone anchor (1) according to one of the Claims 1 until 12 , characterized in that two L-shaped strips (27) are present, the short legs (28) of which have a groove (29) intended for receiving the anchor body (2). Quick coupling (21) for attachment to the bone anchor (1) according to one of the Claims 10 until 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 sides and in the inner circumference of which conically extending toothing counter surfaces (24) are formed. Ensemble (30) comprising a bone anchor (1) according to one of the Claims 1 until 12 , an instrument (26) after claim 13 , a quick coupling (21) according to claim 14 and a reference marker (5).

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