Attachment device for attaching a navigation aid to a bone

Abstract

An attachment device for attaching a navigation aid to a bone includes a screw element and a retaining element The screw element includes a first end, and a second end to which a head portion is connected. Between the first end and the second end there is at least one shank portion, which contains an external thread. A flange element is formed between the shank portion and the head portion. The retaining element includes an opening configured to receive the screw element. The retaining element includes a distal surface and a proximal surface, wherein the proximal surface includes at least one tip-shaped engagement element configured to fix the retaining element in the bone. The distal surface is configured to support the flange element. The screw element is rotatable, but not pivotable, in the retaining element.

Description

ATTACHMENT DEVICE FOR ATTACHING A NAVIGATION AID TO A BONETECHNICAL FIELD

[0001] The invention relates to an attachment device for attaching a navigation aid to a bone. The attachment device can comprise a bone screw. For navigated surgery, for example the replacement of a hip joint, it is necessary to attach a navigation aid to the bone, for example femur, for the duration of the surgery.DESCRIPTION OF RELATED ART

[0002] An example of such a navigation aid is described, for example, in CN 112716605 B. This navigation aid comprises a rod that is attached at one end to a bone of a patient and whose other end includes a ball joint that comprises a receptacle for a connecting element for receiving a tracker. By means of the ball joint, the position of the tracker relative to the bone can be changed. For the end attached to the bone, a bone nail is used which includes a receptacle for a pin by means of which the end of the rod is attached to the bone nail.

[0003] From W02006104538A1 a spinal anchoring device is known, which has a fastening element in the form of a bone screw and a staple with an opening in which the bone screw is received. The staple is used for receiving a tether, wherein a locking device is adapted to secure the tether to the staple. The bone screw serves to improve fixation of the staple in the bone so that the staple cannot loosen when, for example, tensile forces act on the tether that can lead to loosening of the staple.

[0004] It has been shown that bone nails driven into bone tend to cause more severe injury to the bone than bone screws of the type used for the spinal anchorage systems described.

[0005] However, it has been shown that bone screws that are rotated into the bone by means of a twisting motion can become loose or loosen, especially when subjected to shock or vibration.

[0006] _The object of the present invention is to provide an attachment device for attaching a navigation aid to a bone, which is held stationary in the bone. Even when bending forces and / or moments resulting from rotational movements act on the attachment device, the attachment device remains substantially unchanged in its position.SUMMARY OF THE INVENTION

[0007] The object is solved by the features of the claims. Advantageous further developments result from the dependent claims. An advantage of the invention is that the proposed attachment device is very easy to handle.

[0008] When the term "for example" is used in the following description, this term refers to embodiments and / or variants, which is not necessarily to be understood as a more preferred application of the teaching of the invention. Similarly, the terms "preferably", "preferred" are to be understood as referring to an example from a set of embodiments and / or variants, which is not necessarily to be understood as a preferred application of the teaching of the invention. Accordingly, the terms "exemplary", "preferable", or "preferred" may refer to a plurality of embodiments and / or variants.

[0009] The following detailed description contains various examples of embodiments of the attachment device according to the invention. The description of the following exemplary embodiments is to be regarded as exemplary only. In the description and claims, the terms "include", "comprise", "are disposed with" are interpreted as "containing, but not limited to...".

[0010] An attachment device for attaching a navigation aid to a bone includes a screw element and a retaining element. The screw element has a first end and a second end. A head portion adjoins the first end, the head portion beingadjoined by a shank portion extending to the second end, the shank portion including an external thread, a flange member being formed between the head portion and the shank portion. The retaining element includes an opening configured to receive the screw element. The retaining element includes a distal surface and a proximal surface, wherein the proximal surface includes at least one tip-shaped engagement element configured to fix the retaining element in the bone. The distal surface is configured to support the flange element such that the screw element is rotatable, but not pivotable, relative to the retaining element. In particular, the screw element is rotatable relative to the retaining element about a single common axis of rotation.

[0011] According to an embodiment, the first end includes a tip. The tip can be formed as a self-tapping tip. If the screw element is configured as a cannulated screw element, the tip may be omitted. If a cannulated screw element with a continuous longitudinal bore is used, a tool can be used to fix the cannulated screw element in the bone.

[0012] According to an embodiment, the retaining element is configured as an annular retaining element. The term annular retaining element does not mean exclusively an annular retaining element. The annular retaining element may also include an oval or polygonal circumferential shape and / or an oval or polygonal opening.

[0013] According to an embodiment, the distal surface of the retaining element and the flange element form a common support surface.

[0014] According to an embodiment, the opening of the retaining element has an opening width that is smaller than the outer diameter of the flange element, at least in sections, so that in the installed state the flange element rests at least partially on the distal surface of the retaining element.

[0015] According to an embodiment, the opening is formed as a central opening, wherein the retaining element is formed as a rotationally symmetricalbody with an axis of rotation. The opening configured as the central opening contains the axis of rotation.

[0016] According to an embodiment, the retaining element is configured as a disc element.

[0017] According to an embodiment, the support surface is essentially configured as a flat support surface, in particular as an annular flat support surface.

[0018] According to an embodiment, a tip-shaped engagement element or tipshaped engagement elements are at least partially not arranged at the outer edge of the retaining element.

[0019] According to an embodiment, the retaining element includes a docking element. In particular, the docking element and the retaining element are connected to each other in a rotationally fixed manner. Thus, according to this embodiment, the screw element is rotatable but not pivotable relative to the docking element and the retaining element.

[0020] According to an embodiment, the docking element includes a docking element opening, wherein the opening is configured to receive the head portion of the screw element, wherein the head portion is rotatably mounted in the docking element opening. In particular, the docking element opening can include a support surface that is cylindrical or conical in shape.

[0021] According to an embodiment, the docking element includes at least one coupling opening for receiving the navigation aid.

[0022] Thus, the attachment device according to the invention allows unraveling features that provide bending stability and rotational stability of the attachment device. The bending stability is made possible by the use of the screw element. Advantageously, the screw element can be screwed into the bone up to the flange element, so that almost the entire screw length is available to absorb bending forces.

[0023] The screw element can also be configured as a cannulated screw element. If a cannulated screw element is provided, a rod element can be provided to increase bending stability, which can be inserted into the cannulated screw element. Increased bending stability can thus be provided by the combination of the cannulated screw element and the rod element located therein in the installed state.

[0024] Increased rotational stability can be provided by the retaining element, wherein the retaining element includes a proximal surface that includes at least one tip-shaped engagement element. For example, the retaining element can be formed as a rotatable disc with prongs, wherein the prongs engage the bone surface and provide rotational stability. The rotational forces are transmitted to the retaining element, for example, by a pin received in a rod element of the navigational aid. The pin is inserted in a corresponding pin opening of the retaining element so that the rod element can no longer rotate relative to the retaining element.

[0025] According to another embodiment, the docking element may include at least one coupling aperture that can be configured to receive a coupling arm associated with a coupling element of the navigation aid.

[0026] Therefore, one of the main advantages of the attachment device according to the invention is that the rotational stability is obtained independently of the bending stability, since the rotational stability is obtained by the retaining element, but the bending stability is obtained by the length of the screw element.

[0027] The attachment device has a low overall height, therefore the attachment device is only a minor obstacle for soft tissues, so that interference by the attachment device in the surgical procedure is minimal.

[0028] An attachment device for attaching a navigation aid to a bone according to an embodiment comprises a screw element, a retaining element and adocking element, wherein the docking element is configured to receive a navigation aid. The screw element includes a first end configured to be received in the bone, and a second end configured to receive the retaining element and the docking element. Between the first end and the second end is at least one shank portion that includes an external thread, and a head portion. The head portion can include a receiving element for a tool. The screw element includes a flange element disposed between the head portion and the shank portion. The flange element is received between the retaining element and the docking element.

[0029] In particular, the retaining element contains an opening that is configured to receive the screw element. In particular, the distal surface of the retaining element and the flange element form a common support surface. During assembly, the retaining element can thus be guided over the shank portion of the screw element until its distal surface comes into contact with the flange element. A docking element can be slipped over the head portion and also brought into contact with the retaining element. In this position, the docking element can no longer be displaced relative to the retaining element. The retaining element can be fixedly connected to the docking element, for example welded, so that the retaining element and the docking element are no longer movable relative to each other. The screw element can still rotate within the retaining element. However, the screw element cannot perform a pivoting movement relative to the retaining element because the docking element rests on the distal surface of the flange element in the assembled state.

[0030] In particular, the opening can be configured as a central opening. If the flange element is configured as a rotationally symmetrical body, the opening contains the axis of rotation.

[0031] According to an embodiment, the first end includes a tip. This embodiment is used for non-canulated screw elements. In particular, the tip can be configured as a self-tapping tip. Ideally, the pre-drilling step can thus beomitted, so that the screw element can be attached in any position easily and quickly in a single step.

[0032] According to an embodiment, the retaining element is configured as an annular retaining element. The term annular retaining element does not mean exclusively a circular retaining element. The annular retaining element can also include an oval or polygonal circumferential shape and / or an oval or polygonal opening.

[0033] In particular, the docking element and the retaining element are connected to each other in a rotationally fixed manner. In particular, the screw element is rotatable relative to the docking element and the retaining element. In particular, the screw element is not pivotable relative to the docking element or the retaining element. In particular, the support surface is not spherical, so that a pivoting movement of the flange element relative to the retaining element is excluded.

[0034] According to an embodiment, the opening of the retaining element has an opening width that is smaller than the outer diameter of the flange element, at least in sections, so that in the installed state the flange element rests at least partially on the distal surface of the retaining element.

[0035] According to an embodiment, the opening is formed as a central opening, wherein the annular retaining element is formed as a rotationally symmetrical body, wherein the central opening contains the axis of rotation.

[0036] In particular, the support surface is designed as a flat support surface, especially as an annular flat support surface.

[0037] According to an embodiment, the retaining element is formed as a disc element.

[0038] According to an embodiment, the tip-shaped engagement element or the tip-shaped engagement elements are at least partially not arranged at the outer edge of the flange element.

[0039] According to an embodiment, the attachment device for attaching a navigation aid to a bone comprises a screw element, an annular retaining element and a docking element. According to this embodiment, the docking element is configured to receive the navigation aid. In particular, the docking element and the annular retaining element are connected to each other in a rotationally fixed manner. Thus, according to this embodiment, the screw element is rotatable relative to the docking element and the annular retaining element, but not pivotable.

[0040] The screw element includes a first end, which can include a tip, and a second end. A head portion adjoins the second end, the head portion being configured to receive the docking element.

[0041] Between the head portion and the second end there is at least one shank portion which contains an external thread. According to this embodiment, a flange element is formed between the shaft portion and the head portion.

[0042] According to this embodiment, the retaining element includes a distal surface and a proximal surface, wherein the proximal surface includes at least one tip-shaped engagement element configured to fix the retaining element in the bone. The retaining element includes an opening, wherein the opening is configured to receive the screw element. The screw element is rotatably mounted in the opening. In particular, a common support surface is formed by the opening and the distal surface.

[0043] According to an embodiment, the docking element is arranged in the area of the head portion of the screw element. According to this embodiment, the docking element includes a docking element opening. The docking element opening includes a docking element support surface configured to bear on a peripheral surface of the head portion. The docking element support surface can be cylindrical or conical, for example.

[0044] In particular, the head portion of the screw element includes a receiving element for receiving the tool.

[0045] According to any of the preceding embodiments, the head portion of the screw element can comprise a non-rotational symmetrical body. The head portion of the screw element can have a cross-section of an oval or rectangular shape.

[0046] By means of the present invention, it is thus possible to ensure a positionally, rotationally and angularly accurate placement of the navigation aid on a bone.

[0047] The attachment device makes it possible to achieve and maintain a precise position of the navigation aid even when subjected to compressive forces, vibrations or impacts. Compressive forces can, for example, act on the navigation aid and its holder when soft tissue retractors are used during the course of surgery. Vibrations can occur during the processing of the bone and can cause conventional attachment devices with screw elements to loosen. In addition, impacts, for example during the installation of implants, can cause conventional attachment devices to loosen and thus the position of this navigation aid can change undesirably.

[0048] The attachment device according to the invention allows temporary removal of the navigation aid, for example to move the bone, without changing the position of the attachment device.

[0049] In the installed state, the attachment device according to the invention protrudes at most slightly above the bone surface. In particular, the docking element is characterized by a low overall height so that sliding of soft tissues over the attachment device is possible, especially if the attachment device does not contain a navigation aid.

[0050] The attachment of the attachment device according to the invention requires a minimally invasive procedure, so that no additional or extended incision is required.

[0051] The attachment device has only a small installation depth. It is therefore easier to avoid collisions with any implants already in the bone. In particular, the attachment device can also be used for weak bones, for example as a result of osteoporosis, since the retaining element in particular allows a large-area support on the bone surface.

[0052] The attachment device can be mounted quickly, for example using a mounting aid, such as a screwdriver. The use of a mounting aid does not require visual contact with the mounting site on the bone, and mounting can be performed below soft tissue at the depth of the incision. The mounting can be straight or oblique to the bone surface.

[0053] The use of biocompatible materials for the attachment device is possible. In addition, the attachment device according to the invention is compatible with various surgical approaches. In particular, the screw element can be configured as a cannulated screw element.BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The invention is explained in more detail with reference to some embodiments of an attachment device, which is shown in the drawings. It is shown in:

[0055] Fig. la a first embodiment of an attachment device,

[0056] Fig. lb a section through the attachment device according to Fig. la along the section line A-A marked in Fig. la,

[0057] Fig. 2a a second embodiment of an attachment device in a first view,

[0058] Fig. 2b the attachment device according to Fig. 2a in a second view,

[0059] Fig. 2c a partial section through the attachment device according to Fig. 2a along the section line B-B marked in Fig. 2a,

[0060] Fig. 2d a top view of the attachment device according to Fig. 2a,

[0061] Fig. 2e an exemplary embodiment of an annular retaining element in a perspective view,

[0062] Fig. 2f the annular retaining element according to Fig. 2e in a further perspective view,

[0063] Fig. 2g the annular retaining element according to Fig. 2e in a view from below,

[0064] Fig. 3a a perspective view of a navigation aid intended to be coupled to an attachment device according to Fig. 2a,

[0065] Fig. 3b a view of the navigation aid according to Fig. 3a,

[0066] Fig. 3c a section through the navigation aid according to Fig. 3b,

[0067] Fig. 3d a bottom view of the navigation aid according to Fig. 3b,

[0068] Fig. 3e a top view of the navigation aid according to Fig. 3b.DETAILED DESCRIPTION

[0069] Fig. la and Fig. lb show an attachment device 10 according to a first embodiment, wherein Fig. lb shows a section through the attachment device according to Fig. la along the section line A-A marked in Fig. la. The attachment device 10 for attaching a navigation aid to a bone comprises a screw element 1, a retaining element 2 and a docking element 3.

[0070] The docking element 3 is configured to receive the navigation aid. The screw element 1 includes a first end 11, which includes a tip according to this embodiment, and a second end 12. The docking element 3 and the retaining element 2 enclose the second end 12, which thus remains invisible in Fig. la.Between the first end 11 and the second end 12 is a head portion 16 and at least one shank portion 13, which includes an external thread 14. A flange element 15 is formed between the shaft portion 13 and the head portion 16, which is shown in the sectional view in Fig. lb.

[0071] The retaining element 2 includes an opening 25 configured to receive the screw element 1. The retaining element 2 contains a distal surface 21 and a proximal surface 22, wherein the proximal surface 22 contains at least one tipshaped engagement element 23, which is configured to fix the retaining element 2 in the bone. The distal surface 22 is configured to support at least one of the flange element 15 or the docking element 3. The distal surface 21 and the flange element 15 form a common support surface. The distal surface 21 is configured to support the flange element 15 in such a way that the screw element 1 can be rotated in the retaining element 2 but cannot be pivoted.

[0072] According to the present embodiment, the docking element 3 and the retaining element 2 are connected to each other in a rotationally fixed manner. In particular, the docking element 3 and the retaining element 2 can be non- detachably connected to each other by a welded connection. A welded connection is to be regarded as only one embodiment of a non-detachable connection. Any connection that allows coupling of the docking element 3 with the retaining element 2 may be used, for example a snap connection, a snap-in connection or even a connection obtained using an adhesive. Thus, according to this embodiment, the screw element 1 is rotatable relative to the docking element 3 and the retaining element 2.

[0073] The retaining element can be configured in particular as an annular retaining element. An embodiment for an annular retaining element is shown in Figs. 2e to 2f, which can also be used for this embodiment. The opening 25 of the retaining element 2 can have an opening width that is smaller, at least in sections, than the outer diameter of the flange element 15, so that in the installed state the flange element 15 rests at least partially on the distal surface21 of the retaining element 2. In particular, the opening 25 of the retaining element 2 can be circular. The circular opening 25 has an inner diameter that is smaller than the outer diameter of the flange element 15, so that in the installed state the flange element 15 rests on the distal surface of the annular retaining element 2. The screw element 1 is thus accommodated in the annular retaining element 2 in such a way that its rotational movement cannot be impeded by the retaining element and the retaining element 2 remains connected to the screw element 1 in such a way that it cannot be lost.

[0074] According to this embodiment, the screw element 1 is not pivotable relative to the docking element 3 or the retaining element 2.

[0075] According to this embodiment, the support surface is essentially configured as a flat support surface, in particular as an annular flat support surface.

[0076] In particular, the opening 25 can be configured as a central opening. In particular, the annular retaining element 2 can be configured as a rotationally symmetrical body, wherein the opening 25 formed as a central opening can contain the axis of rotation.

[0077] In particular, the retaining element 2 is configured as a disc element. According to the present embodiment, the retaining element 2 includes a circumferential outer edge 24, which is configured as a projection and holder for the docking element 3. In particular, a weld seam can be applied to the distal end of the edge 24, which serves to connect the retaining element 2 to the docking element 3.

[0078] According to this embodiment, the tip-shaped engagement element or elements 23 are at least partially not attached to the outer edge of the retaining element 2. The support surface extending between the engagement elements 23 and the outer edge 24 serves to better distribute the compressive forces acting on the retaining element 2 on the bone and counteracts load peaksacting on the bone, which may occur when shocks act on the attachment device, which may be caused, for example, by a shock force acting on the navigation aid.

[0079] According to the present embodiment, the screw element contains a receiving element 17 for an assembly tool, for example a screwdriver, at its second end 12. Fig. lb shows an example of a hole for a hexagon located in the head portion 16.

[0080] According to the present embodiment, the docking element 3 includes a coupling opening 37 for the navigation aid. According to the present embodiment example, the coupling opening 37 is configured as a polygonal opening that can have a triangular, quadrangular, or polygonal cross-sectional area. In addition, the docking element 3 includes a plurality of flushing openings 33. The flushing openings 33 enable cleaning of the docking element 3 as well as the receiving element 17. The cleaning can prevent the formation of germs in the cavities required by the various openings in the docking element 3 and the screw element 1.

[0081] According to an embodiment not shown, the flange element 15 is held in a groove of the retaining element 2. The navigation aid is held in a bore extending in the screw element 1. According to this embodiment, the docking element 3 can be omitted and thus an attachment device with a particularly low overall height can be realized.

[0082] According to an embodiment not shown, the docking element can be formed by the head portion of the screw element. In particular, the head portion can include receiving openings for gripping arms of a coupling element. The gripping arms can also serve to couple the screw element to the retaining element, so that a rotational movement of the screw element relative to the retaining element is blocked only when the navigation aid is attached.

[0083] Figs. 2a to Fig. 2d show an attachment device 10 according to a second embodiment, with Fig. 2c showing a section through the attachment device according to Fig. 2a along the section line B-B marked in Fig. 2a. The same reference signs as for the embodiment shown in Fig. la and Fig. lb have been used for identical or similarly acting elements. The view shown in Fig. 2b is obtained by rotating Fig. 2a counterclockwise through an angle of 90 degrees about the axis of rotation running in the vertical direction in Fig. 2a or Fig. 2b. Fig. 2d is a top view of the attachment device according to Fig. 2a.

[0084] According to the embodiment shown in Figs. 2a to 2d, the attachment device 10 for attaching a navigation aid to a bone comprises a screw element 1, a retaining element 2, and a docking element 3. The screw element 1 includes a first end 11, which includes a tip according to this embodiment, and a second end 12. A head portion 16 adjoins the second end 12, the head portion 16 being adjoined by a shank portion 13 that extends to the second end 12, wherein the shank portion 13 includes an external thread 14. A flange element 15 is formed between the head portion 16 and the shank portion 13. The retaining element 2 includes an opening 25 formed to receive the screw element 1. The retaining element 2 includes a distal surface 21 and a proximal surface 22, the proximal surface 22 including at least one tip-shaped engagement element 23 configured to fix the retaining element 2 in the bone. The distal surface 21 is configured to support the flange element 15 such that the screw element 1 is rotatable, but not pivotable, in the retaining element 2.

[0085] According to the present embodiment, the head portion 16 of the screw element 1 is configured to receive a docking element 3. The docking element 3 is supported on the retaining element 2 and surrounds the head portion like a jacket. The retaining element 2 and the docking element 3 are permanently connected to one another, for example by means of a welded connection, adhesive connection or a form-fitting connection, the screw element 1 being rotatably mounted in the retaining element 2 and in the docking element 3. For example, a welded connection or adhesive connection can be provided at theperipheral edge 36 of the docking element 3. Alternatively, a snap connection or a snap-in connection can also be provided, which is not shown in the drawings. According to the present embodiment, the docking element 3 and the retaining element 2 are connected to each other in a rotationally fixed manner. Thus, according to this embodiment, the screw element 1 is rotatable relative to the docking element 3 and the retaining element 2.

[0086] The retaining element can be configured in particular as an annular retaining element. An example of an annular retaining element is shown in Figs. 2e to 2f, which can also be used for this embodiment.

[0087] The opening 25 of the retaining element 2 can have an opening width that is smaller, at least in sections, than the outer diameter of the flange element 15, so that in the installed state the flange element 15 rests at least partially on the distal surface 21 of the retaining element 2. The screw element 1 is thus accommodated in the annular retaining element 2 in such a way that its rotational movement cannot be impeded by the retaining element and the retaining element 2 remains connected to the screw element 1 in such a way that it cannot be lost.

[0088] According to this embodiment, the screw element 1 is not pivotable relative to the docking element 3 or the retaining element 2. According to this embodiment, the support surface is essentially configured as a flat support surface, in particular as an annular flat support surface.

[0089] In particular, the opening 25 can be configured as a central opening. In particular, the annular retaining element 2 can be configured as a rotationally symmetrical body, wherein the opening 25 configured as a central opening can contain the axis of rotation.

[0090] In particular, the retaining element 2 is configured as a disc element. According to the present embodiment, retaining element 2 includes a circumferential outer edge 24 that projects beyond docking element 3 as aprotrusion. In particular, the distal surface within the edge 24 can include a shoulder formed to receive an indentation of the docking element 3.

[0091] According to this embodiment, the tip-shaped engagement element or elements 23 are at least partially not attached to the outer edge 24 of the retaining element 2. The support surface extending between the engagement elements 23 and the outer edge 24 serves to better distribute the compressive forces acting on the retaining element 2 on the bone and counteracts load peaks acting on the bone that may arise when impacts act on the attachment device, which may be caused, for example, by an impact force acting on the navigation aid.

[0092] According to the present embodiment, the screw element 3 contains a receiving element 17 for an assembly tool, for example a screwdriver, at its second end 12. Fig. 2c shows an example of a hole for a hexagon located in the head portion 16. In addition, according to this embodiment, the screw element 3 contains a bore 18 which is configured to receive a corresponding pin element 46 of the navigation aid, see for example Fig. 3b.

[0093] According to the present embodiment, the docking element 3 includes a coupling element 37 for the navigation aid. According to the present embodiment, the coupling element 37 is formed as a polygonal opening that may have a triangular, quadrangular, or polygonal cross-sectional area. In addition, the docking element 3 includes a plurality of flushing openings 33. The flushing openings 33 enable cleaning of the docking element 3 as well as the receiving element 17. The cleaning can prevent the formation of germs in the cavities required by the various openings in the docking element 3 and the screw element 1.

[0094] The term annular retaining element does not refer exclusively to an annular retaining element with an annulus of circular shape. The annular retaining element can also include an oval or polygonal peripheral shape and anoval or polygonal opening. Fig. 2e to Fig. 2g show an exemplary embodiment of an annular retaining element.

[0095] The annular retaining element 2 includes a distal surface 21 and a proximal surface 22, wherein the proximal surface 22 includes at least one tipshaped engagement element 23 configured to fix the annular retaining element 2 in the bone.

[0096] The docking element 3 includes a docking element opening 35, wherein the docking element opening 35 is configured to receive the screw element 1. The head portion 16 is rotatably supported in the docking element opening 35. In particular, a common docking element supporting surface is formed by the docking element opening 35 and the head portion 16. The docking element support surface can be cylindrical or conical in shape.

[0097] According to this embodiment, the screw element 1 is rotatable relative to the retaining element 2. According to the present embodiment, the docking element 3 is arranged in the head portion 16 of the screw element.

[0098] According to the present embodiment, the head portion 16 of the screw element 1 includes a receiving element 17 for receiving the screwdriver.

[0099] The docking element 3 according to the embodiment shown in Figs. 2a- 2d has a lower overall height than the associated docking element according to Fig. la or Fig. lb. In order to ensure sufficient bending stability of the navigation aid 4 to be connected to the fastening device 10, exemplarily shown in Figs. 3a-3d, it is therefore advantageous to provide a bore 18 in the interior of the screw element 1. The bore 18 serves to receive a pin element 46 of the navigation aid 4, as exemplarily shown in Figs. 3a-3d.

[0100] To prevent cells or other organic materials from accumulating in the bore 18, the bore 18 also contains a flushing opening 19.

[0101] Fig. 3a shows a perspective view of an exemplary navigation aid 4, which may be intended to be coupled to an attachment device 10 according toFig. 2a. The navigation aid 4 comprises a first end portion 41, a second end portion 42, and a rod element 43 connecting the first and second end portions 41, 42.

[0102] Fig. 3b shows a view of the navigation aid 4 according to Fig. 3a. In Fig. 3b, the rod element 43 is not shown completely so that the first end portion 41 and the second end portion 42 can be shown enlarged. The first end portion 41 is formed as a receiving element 44 for a measuring device or a position indicating element. The receiving element 44 is shown in Fig. 3e in a top view.

[0103] The second end portion 42 includes a coupling element 45 and a pin element 46, the pin element 46 being received and retained in the bore 18 shown in Fig. 2c. The coupling element 45 includes a plurality of coupling arms 47 engageable with respective openings of the coupling element 37 of the docking element 3. In Fig. 2d, four such coupling apertures 37 are provided. Correspondingly, the coupling element according to Fig. 3b contains four coupling arms 47.

[0104] Also visible in Fig. 3b is an optical marking element 40, which enables the correct orientation of the navigation aid with respect to the attachment device 10. The docking element 3 can also have a corresponding optical marking element 30, which is visible in Fig. 2b and Fig. 2d.

[0105] Fig. 3c shows a section through the navigation aid according to Fig. 3b, which shows the first end portion 41, the second end portion 42 and the rod element 43. The first end portion 41 is designed as a receptacle element 44 for a measuring device or a position indicator element and is attached to the first end of the rod element 43 according to this embodiment. For this purpose, the bore provided in the receiving element 44 may have slightly smaller dimensions than the first end of the rod element 43, so that the receiving element 44 can only be connected to the rod element 43 by applying a compressive force or by utilizing thermal expansion, resulting in an interference fit. The receiving element 44 therefore has a defined, unchangeable position.

[0106] In Fig. 3c, the coupling element 45 is also shown in section. The coupling element 45 can also be connected to the rod element 43 by means of an interference fit, so that its position is predetermined. In Fig. 3c, two of the coupling arms 47 are also visible, which are arranged in a cavity 48 configured to receive the docking element 3 according to Figs. 2a-2d.

[0107] Fig. 3d shows a bottom view of the navigation aid according to Fig. 3b. In this view, the second end portion 42 is visible, which includes the pin element 46 and the coupling element 45. In Fig. 3b, four coupling arms 47 are shown as an example, which are intended to be received in the associated openings of the coupling element 37 of the docking element 3.

[0108] Fig. 3e shows a top view of the navigation aid 4 according to Fig. 3b. In particular, the receiving element 44 is visible. According to this embodiment, the receiving element 44 has a trapezoidal cross-sectional area. The measuring device or position indicating device that can be connected to the receiving element 44 has a corresponding groove, so that the measuring device or position indicating device can be plugged onto the receiving element 44. A corresponding visually recognizable marking can be provided on the receiving element 44, which can provide assistance for the correct mounting of the measuring device or position indicating device, here for example in the form of the letter F.

[0109] According to any of the preceding embodiments, the head portion 16 of the screw element 1 can comprise a non-rotational symmetrical body. The head portion 16 of the screw element 1 can have a cross-section of an oval or rectangular shape.

[0110] It is obvious to a person skilled in the art that many further modifications in addition to the described embodiments are possible without deviating from the inventive concept. Of course, it is possible to combine in particular the embodiments for the docking element with each other as desired in order to achieve optimum properties of the attachment device for thecorresponding application. Thus, the subject matter of the invention is not limited by the preceding description and is determined by the scope of protection defined by the claims. In interpreting the claims or the description, the broadest possible reading of the claims is authoritative. In particular, the terms "comprising" or "including" are intended to be interpreted as referring to elements, components, or steps in a non-exclusive meaning, thereby indicating that the elements, components, or steps may be present or may be used, may be combined with other elements, components, or steps not explicitly recited. When the claims refer to an element or component from a group that may consist of A, B, C... N elements or components, this phrase is intended to be interpreted as requiring only a single element of that group, and not a combination of A and N, B and N, or any other combination of two or more elements or components of that group.

Claims

What is claimed is1. An attachment device for fastening a navigation aid to a bone, comprising a screw element and a retaining element, wherein the screw element has a first end and a second end, wherein a head portion adjoins the first end, wherein a shank portion adjoins the head portion and extends to the second end, wherein the shank portion contains an external thread, wherein a flange element is formed between the head portion and the shank portion, wherein the retaining element includes an opening configured to receive the screw element, wherein the retaining element includes a distal surface and a proximal surface, wherein the proximal surface includes at least one tip-shaped engagement element which is configured to fix the retaining element in the bone, wherein the distal surface is configured to support the flange element in such a way that the screw element can be rotated, but not pivoted, in the retaining element.

2. The attachment device of claim 1, wherein the screw element is rotatable relative to the retaining element about a single common axis of rotation.

3. The attachment device of claim 1, wherein the retaining element is configured as an annular retaining element.

4. The attachment device of claim 1, wherein the distal surface of the retaining element and the flange element form a common support surface.

5. The attachment device of claim 1, wherein the opening of the retaining element has an opening width which, at least in sections, is smaller than an outer diameter of the flange element, so that, in an installed state, the flange element rests at least partially on the distal surface of the retaining element.

6. The attachment device of claim 1, wherein the opening is formed as a central opening, wherein the retaining element is formed as a rotationallysymmetrical body having an axis of rotation, wherein the opening formed as the central opening contains the axis of rotation.

7. The attachment device of claim 1, wherein the retaining element is formed as a disc element.

8. The attachment device of claim 3, wherein the support surface is substantially configured as a planar support surface.

9. The attachment device of claim 8, wherein the support surface is configured as an annular planar support surface.

10. The attachment device of claim 1, wherein the at least one tip-shaped engagement element is at least partially not arranged on an outer edge of the retaining element.

11. The attachment device of claim 1, wherein the retaining element includes a docking element.

12. The attachment device of claim 10, wherein a docking element and an annular retaining element are connected to one another in a rotationally fixed manner.

13. The attachment device of claims 10, wherein the screw element is rotatable, but not pivotable, relative to the docking element and the retaining element.

14. The attachment device of claim 10, wherein a docking element includes a docking element opening.

15. The attachment device of claim 14, wherein the docking element opening is configured to receive the head portion of the screw element.

16. The attachment device of claim 15, wherein the head portion is rotatably supported in the docking element opening.

17. The attachment device of claim 14, wherein the docking element opening includes a docking element support surface that is of cylindrical or conical shape.

18. The attachment device of claim 10, wherein a docking element includes at least one coupling opening for receiving the navigation aid.

19. The attachment device of claim 1, wherein the head portion of the screw element comprises a non-rotational symmetrical body.

20. The attachment device of claim 1, wherein the head portion of the screw element has a cross-section of an oval or rectangular shape.

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