Bone anchoring device

Abstract

A bone anchoring device is provided, comprising an anchoring element (1, 1') comprising a shank (2) for anchoring in a bone and a head (3, 3') having an outer surface (30) with a spherical portion; wherein the shank (2) and the head (3, 3') are separate components configured to be connected to each other; and wherein the head (3, 3') comprises a driving structure (31, 31') for engagement with a driving tool.

Description

TECHNICAL FIELD

[0001] The present invention relates to a bone anchoring device which can generally be applied in orthopedic and trauma surgery and more particularly in spinal surgery. BACKGROUND

[0002] In spinal surgery, one or several motion segments of the spinal column are connected by means of a rod. The rod is anchored to the vertebrae using mono- or polyaxial bone anchoring devices. Such bone anchoring devices generally comprise a bone anchoring element to be anchored in the pedicle of a vertebra, for example, wherein in the case of polyaxial devices, the bone anchoring element is pivotably connected to a receiving part. The receiving part comprises a recess for receiving the rod and a fixation member for fixing or locking the structure.

[0003] US 6,835,196 B2, for example, describes a polyaxial bone anchoring device having a screw with a threaded section and a head portion with a spherical shape and a receiving portion for connecting the screw to a rod. The threaded section and the spherical head portion of the screw are separate components. With such a device, the threaded section can be shortened to a desired length during application of the device, before or after implantation, and then connected to the head portion and the receiving portion.

[0004] In US 2008 / 0132957 Al, a bone anchoring device is described which comprises a shank to be anchored in a bone or vertebra, a head portion, and a receiving part receiving the head portion for connecting the shank to a rod. The shank and the head portion are separate components. Since the shank and the head portion are formed as separate components, in the use of the bone anchoring device, a suitable shank can be selected according to the application and connected to the head portion for forming the bone anchoring device. In particular, shanks of different lengths can be provided in combination with the head portion.

[0005] US 2014 / 0277158 Al describes a bone anchor assembly having a multi-component bone anchor configured to allow a shank of the bone anchor to be bottom-loaded into a receiver member. One bone anchor assembly has a shank having a distal threaded portion and a proximal head portion, a ball having a spherical outer surface and a central cavity sized to receive the head portion of the shank, and a clip configured to engage between the head portion and the ball to effectively lock the ball in engagement with the shank. SUMMARY

[0006] It is an object of the present invention to provide a bone anchoring device which allows treating various orthopedic, in particular spinal, conditions, symptoms and / or diseases in an improved or alternative way and / or opens up additional options for the use of the bone anchoring device.

[0007] The object is solved by a bone anchoring device according to claim 1. Further developments are given in the dependent claims.

[0008] According to one embodiment, the bone anchoring device comprises an anchoring element comprising a shank for anchoring in a bone and a head having an outer surface with a spherical portion, wherein the shank and the head are separate components configured to be connected to each other, and wherein the head comprises a driving structure for engagement with a driving tool.

[0009] The driving structure has an increased size compared to known anchoring elements with a spherical head. This allows inserting, respectively screwing the bone anchoring element into a bone with increased torque.

[0010] In a further development, a receiving component for receiving a head and for connecting the bone anchoring element to a rod is provided. Thus, the bone anchoring element and the receiving component can form a polyaxial bone anchoring device, wherein the shank can be pivoted relative to the receiving component in various angles and can be fixed at a particular angular position. A pressure element can be provided to transmit the force exerted by the fixation member to the head. Alternatively, pressure can be transmitted directly via the rod onto the head.

[0011] The shank further comprises an engagement portion for a driving tool. Thus, the shank can be inserted into a bone first and then the receiving component with the head mounted therein can be placed onto the shank. As the shank can be inserted without being coupled to the receiving component, the insertion step becomes easy as the visibility and the available space at the implantation site increase. Once the insertion depth of the shank needs to be corrected or the bone anchoring device has to be removed, the driving structure of the head can be engaged and the required steps can be effectively performed.

[0012] In a particular embodiment, the shank can have a large outer diameter. The engagement portion of the shank can also be designed to allow applying high torques, for example.

[0013] Moreover, the bone anchoring device is robust and the receiving component with the inserted head can be easily connected to the shank.

[0014] In another mode of use, the head and the shank can be assembled before coupling the head to the receiving component.

[0015] Various heads with different drive structures can be combined with specific handles. These different drive structures can be, for example, a quincunx drive structure or... Drive structure. Additionally, modular systems can be provided, where various heads can be combined with various handles of different lengths, diameters, threaded or bone-jointed structures, or other different properties.

[0016] In another particular embodiment, the bone anchoring device includes a position indicating structure that indicates the angular position of the head with the handle relative to the receiving component at a specific angle (e.g., zero angle position).

[0017] The bone anchoring device may further include a bone plate having a hole with a seat for a head of the bone anchoring element, and optionally include a locking member for locking the head in the hole. Attached Figure Description

[0018] Further features and advantages of the invention will become apparent from the description of the embodiments with reference to the accompanying drawings. In the drawings:

[0019] Figure 1 : An exploded perspective view of a first embodiment of the bone anchoring device is shown.

[0020] Figure 2 : Show Figure 1 A three-dimensional view of a bone anchoring device in its assembled state.

[0021] Figure 3 : Show Figure 1 and Figure 2 A cross-sectional view of the multi-axis bone anchoring device, taken in a plane extending through the center of the receiving component and the center of the head, and including the axis of the handle.

[0022] Figure 4 : Show Figures 1 to 3 A perspective view of the shank of the bone anchoring element of the bone anchoring device taken from the top.

[0023] Figure 5 : Show Figure 4 Side view of the upper part of the handle.

[0024] Figure 6 : Show Figure 4 and Figure 5 A top view of the handle.

[0025] Figure 7 : Show Figures 1 to 3 A three-dimensional view of the head of the bone anchoring device taken from the top.

[0026] Figure 8 : shows Figure 7 a perspective view taken from the bottom of the head.

[0027] Figure 9 : shows Figure 7 and Figure 8 a top view of the head.

[0028] Figure 10 : shows Figures 7 to 9 a sectional view taken along the line A-A in Figure 9 of the head.

[0029] Figure 11 : shows Figures 1 to 3 a perspective view taken from the top of the receiving part of the bone anchoring device.

[0030] Figure 12 : shows Figure 11 a perspective view taken from the bottom of the receiving part.

[0031] Figure 13 : shows Figure 11 and Figure 12 a top view of the receiving part.

[0032] Figure 14 : shows Figures 11 to 13 a sectional view taken along the line B-B in Figure 13 of the receiving part.

[0033] Figure 15 : shows Figures 1 to 3 a perspective view taken from the top of the pressure member of the bone anchoring device.

[0034] Figure 16 : shows Figure 15 a perspective view taken from the bottom of the pressure member.

[0035] Figure 17 : shows Figure 15 and Figure 16 a top view of the pressure member.

[0036] Figure 18a : shows Figures 15 to 17 a sectional view taken along the line D-D in Figure 17 of the pressure member.

[0037] Figure 18b : shows Figure 18a an enlarged detail.

[0038] Figures 19a to 19c : shows a perspective view taken from the top of the step of mounting the head of the bone anchoring element to the handle.

[0039] Figures 20a to 20c : cross-sectional view showing the steps illustrated in Figures 19a to 19c : cross-sectional view showing the steps illustrated in

[0040] Figures 21a to 21e : cross-sectional view showing the steps illustrated in Figure 21c : enlarged view of details of Figure 21b

[0041] Figures 22a to 22d : cross-sectional view showing the steps illustrated in

[0042] Figure 23a : cross-sectional view showing the steps illustrated in Figures 1 to 3 : cross-sectional view of the bone anchoring device of

[0043] Figure 23b : cross-sectional view of the polyaxial bone anchoring device of Figure 23a

[0044] Figure 24 : cross-sectional view of a modified embodiment of the bone anchoring device with inserted rod and fixation member.

[0045] Figure 25 : perspective view showing an embodiment of the system of a handle and two exchangeable heads forming the bone anchoring element of the bone anchoring device.

[0046] Figure 26 : perspective exploded view showing the bone anchoring device according to the second embodiment.

[0047] Figure 27 : perspective view showing the bone anchoring device of Figure 26 in an assembled state.

[0048] Figure 28 : perspective view from the top showing the head of the bone anchoring device of Figure 26 and Figure 27

[0049] Figure 29 : perspective view from the bottom showing the head illustrated in Figure 28

[0050] Figure 30 : top view showing the head of Figure 28 and Figure 29 ​​​​​

[0051] Figure 31 : shows Figures 28 to 30 a sectional view taken along the line F-F in Figure 30 .

[0052] Figure 32 : shows Figure 26 and Figure 27 a perspective view taken from the top of the receiving part of the bone anchoring device.

[0053] Figure 33 : shows Figure 32 a perspective view taken from the bottom of the receiving part.

[0054] Figure 34 : shows Figure 32 and Figure 33 a top view of the receiving part of the bone anchoring device.

[0055] Figure 35a : shows Figure 34 a sectional view taken along the line G-G in Figure 34 .

[0056] Figure 35b : shows Figure 35a an enlarged view of a detail.

[0057] Figures 36a to 36d : shows Figure 26 and Figure 27 a sectional view of the bone anchoring device assembled.

[0058] Figures 37a to 37c : shows a sectional view of the pivoting of the bone anchoring element relative to the receiving part and the locking of the pivoted position after the insertion of the rod and the fixation member. DETAILED DESCRIPTION

[0059] With reference to Figures 1 to 3 , the bone anchoring device according to the first embodiment comprises a bone anchoring element 1 comprising a shank 2 and a separate head 3. The bone anchoring element 1 is pivotably coupled via the head 3 to a receiving part 5 which receives a pressure member 6 for transmitting the pressure exerted by a fixation member 7 onto the head 3. A rod 100 is used to couple at least two bone anchoring devices together. The bone anchoring device is polyaxial, which means that the anchoring element can assume various angular positions of the shank axis relative to the receiving part and can be locked in each of these positions.

[0060] As in Figures 4 to 6As will be described in more detail, the shank 2 comprises a first end 2a and an opposite end 2b, and a bone thread portion 21 in at least a portion of the length of said shank. The bone thread is configured to engage bone. In the shown embodiment, the bone thread portion 21 extends almost the entire length of the shank from an end 22 at the second end 2b up to a neck portion 23. At the first end 2a, an engagement portion 24 is formed, said engagement portion comprising an outer surface with a structure configured to be engaged by a driving tool, such as a star-shaped structure, a torx-shaped structure or a polygonal outer profile. The maximum outer width of the engagement portion 24 can be smaller than the maximum outer diameter of the bone thread portion 21. Thus, in this embodiment, the shank has a relatively large diameter. More specifically, the maximum outer diameter of the bone thread portion 21 can be larger than the maximum outer diameter of the head 3. The engagement portion 24 can be delimited by a substantially cylindrical portion 25, said cylindrical portion forming an annular ring which can act as a stop for the driving tool.

[0061] With reference to Figures 7 to 10 The head 3 comprises a first end 3a and an opposite second end 3b, and a segment-shaped outer surface 30 between the first and second end. The segment shape is such that the outer surface 30 contains the maximum diameter E of the head in a direction perpendicular to the central axis C, which coincides with the shank axis when the head 3 is mounted to the shank 2. Also, the distance from the maximum diameter E to the first end 3a can be smaller than the distance between the maximum diameter E and the second end 3b. More specifically, the axial height of the upper portion of the head 3, i.e. the axial height between the maximum diameter E and the first end 3a, is as small as possible in order to on the one hand still allow pivoting and on the other hand provide enough space for a driving structure 31 on said first end. The driving structure 31 in this embodiment comprises a recess extending in the axial direction from the first end 3a towards the second end 3b to a distance beyond the maximum diameter E. Said recess comprises an inner profile having a star shape, more specifically a torx shape, comprising six radially extending longitudinal grooves 31a with rounded ends and arranged at regular distances. The distance of the outermost ends of the grooves 31a in the radial direction, as seen from the central axis C, is such that the driving structure 31 extends over substantially the entire surface at the first end 3a, leaving only a small rim 32 to the outer segment-shaped surface 30. With this design, the driving structure 31 allows engagement of the head and application of increased torque to the shank 2.

[0062] At a distance from the first end 3a, a circumferential groove 33 is formed in the outer segment-shaped surface 30. The groove 33 can extend completely around the central axis C. Also, the groove 33 can be closer to the first end 3a than to the axial position of the maximum diameter E. The depth of the groove 33 in the radial direction can be such that it extends into the grooves 31a of the driving structure 31, as Figure 7 andFigure 10 as depicted in the middle.

[0063] At the second end 3b, a counter engagement portion 34 is formed, which is a recess configured to receive the engagement portion 24 of the handle 2. In other words, the inner profile of the counter engagement portion 34 substantially matches the outer profile of the engagement portion 24 of the handle. Furthermore, the recess forming the counter engagement portion 34 has a depth that substantially corresponds to the axial length of the engagement portion 24. In addition, the recess has a slightly conical inner wall tapering towards the second end 3b. The driving structure 31 and the counter engagement portion can be in communication with each other. A shoulder 34a between the recess and the driving structure 31 forms a stop for the insertion of the engagement portion 24 of the handle.

[0064] The head 3 is at least partially flexible in the region adjacent to the second end 3b. This is achieved by a plurality of longitudinal slits 35 that open towards the second end 3b and extend at least up to the maximum diameter E, preferably up to the circumferential groove 33. The number and width of the slits 35 are chosen such that the head 3 exhibits sufficient flexibility in the lower portion adjacent to the second end 3b to allow the engagement portion 24 to be inserted in a snap-in manner and to be held in the recess. The conical inner wall of the recess allows a close engagement of the engagement portion 24.

[0065] Reference Figures 11 to 14 The receiving member 5 will be described in more detail. The outer shape of the receiving member 5 can be substantially cylindrical. It has a first or top end 5a, a second or bottom end 5b, and a passage 50 extending completely through the receiving member 5 from the first end 5a to the second end 5b. When the head 3 is in the zero position in the receiving member 5, the central longitudinal axis C coincides with the central longitudinal axis C of the head 3. The opening 51 at the second end 5b can have such dimensions that at least a portion of the lower end of the head 3 can extend through it. Adjacent to the second end 5b, the passage 50 forms an accommodation space for at least a portion of the head 3. More specifically, adjacent to the second end 5b, a seat 52 is formed for the head 3. The seat 52 can have a hollow spheroid shape that matches the spheroid shape of the head 3. When the head 3 is accommodated in the lower portion of the receiving member adjacent to the second end 5b, it is supported in the seat 52 and is configured to pivot in the seat like a ball and socket joint. Any other shape of the seat that provides this function can also be implemented.

[0066] Adjacent to the seat 52, the channel 50 widens into a main section 53 having a substantially constant inner diameter. From the first end 5a, a substantially U-shaped recess 54 is formed, resulting in two free leg portions 55. The substantially U-shaped recess 54 forms a channel configured to receive the stem 100 therein. Further, adjacent to the first end 5a, an internal thread is formed on the leg portions 55, which is configured to cooperate with a fixing member 7, such as a set screw. The internal thread can be of any thread type, however, preferably a thread type that reduces the flare of the leg portions 55, such as a square thread or a flat thread. At the circumferential center of the leg portions 55, a transverse through hole 57 is formed in each leg portion, respectively. The axial through hole 57 can be at an axial position above the bottom of the substantially U-shaped recess 54 and below the threaded portion 56. The through hole 57 is for receiving a pin 4, which is configured to extend completely through the through hole 57 into the channel 50. At the lowermost end of the internal thread 56, a circumferential groove 58 or undercut is formed on each leg portion 55, which provides an abutment for a part of the pressure member 6 by its upper surface 58a. An additional tool engagement recess 59 can be provided in the outer surface of the leg portions 55, respectively.

[0067] Reference is made to Figures 15 to 18b The pressure member 6 comprises a first end 6a and an opposite second end 6b and is configured to be arranged in the receiving member 5 such that the second end 6b faces the second end 5b of the receiving member. An upper portion 60 of the pressure member 6 is substantially cylindrical such that it fits into the cylindrical portion 53 of the channel 50 in the receiving member and can move to some extent in the axial direction in said cylindrical portion. Thus, when the pressure member 6 is arranged in the receiving member 5, the cylinder axis C coincides with the central longitudinal axis of the receiving member 5. Two opposite leg portions 62 are vertically standing from an upper surface 61 of the cylindrical portion 60, offset 180°. The leg portions 62 can have flat inner walls facing each other and a cylindrical outer wall corresponding to the shape of the cylindrical portion 60. At the first end 6a, each leg portion comprises an outwardly protruding rim 63 extending in a radial direction beyond the outer surface of the cylindrical portion 60. The leg portions 62 have a length and a thickness such that they are at least partly flexible in the area of their free ends and can be compressed towards each other and elastically moved back to their straight position. The upper surface of the protruding rim 63 forms the first end 6a of the pressure member 6. In each leg portion 62, an axial elongated hole 64 is provided for receiving a part of the pin 4.

[0068] The pressure member 6 is further configured to support the stem 100 and thus comprises a recess 65 extending perpendicular to the cylinder axis C of the cylindrical portion 60. The recess 65 forms a support surface for the inserted stem 100. The cross section of the recess 65 can be substantially V-shaped, the V-shape preferably having a rounded bottom, as particularly in the embodiment shown in the figures. The recess 65 is formed in the leg portions 62, such that the recess 65 is accessible from the first end 6a of the pressure member 6.Figure 18a The hole 66, which is coaxial with the cylinder axis of the cylindrical portion 60, extends from the upper surface 61 of said cylindrical portion to the second end 6b and provides access to the head 3 for a driving tool. The inner diameter of the hole 66 is thus such that it is at least as large as the maximum width of the recess comprising the driving structure 31 of the head, so that when the driving tool extends through the hole 66, it can engage the driving structure 31. At a distance from the second end 6b, a substantially spherical recess 67 is formed, the shape of which matches the outer spherical shape of the head 3. The height of the spherical portion 67 in axial direction is such that when the head 3 is mounted to the pressure member 6 and the receiving member 5 and rests in the seat 52 of the receiving member in a zero angle position of the handle 2, the upper part of the head 3 between the groove 33 and the first end 3a is located within the spherical recess 67. Moreover, the spherical recess 67 and the seat 52 together form a spherical pivot support for the head 3, as can be seen in particular in Figs. 23 and 24. Figure 24

[0069] Between the spherical recess 67 and the second end, the pressure member 6 comprises a circumferentially extending inner protrusion 68 projecting inwardly to the central axis C. The position at which the protrusion 68 is located and the shape it has are adapted to the position and shape of the circumferential groove 33 in the head 3 when the head 3 extends into the spherical recess 67 of the pressure member. In order to be able to engage and disengage from the groove 33, the protrusion can be circular. Moreover, the protrusion 68 is configured to engage the groove 33 when the head 3 is supported in the seat 52 of the receiving member 5. Since the groove 33 and the protrusion 68 extend perpendicular to the central axis C, the engagement is achieved when the head 3 is in the zero angle position of the handle relative to the receiving member 5. This engagement can produce an audible or tactile feedback at the moment of engagement. Thus, the groove and the protrusion form a position indicating structure configured to indicate a specific position of the handle relative to the receiving member. In a specific example, the specific position is the zero position in which the handle 2 is coaxial with the receiving member 5. Between the protrusion 68 and the second end 6b, an outwardly tapering section 68a can be provided, which facilitates the insertion of the head 3 into the pressure member 6. When the head 3 is pivoted, the outwardly tapering section 68a can form a ramp for the head 3, so that the protrusion 68 can more easily move out of the groove 33.

[0070] The outer surface 69 between the second end and a distance up to and beyond the spherical section 67 can be slightly tapered towards the second end 6b, whereby a step 69a can be formed. In this way, the wall thickness is slightly reduced, so that the protrusion 68 can more easily snap into the groove 33.

[0071] ​The components and parts of the bone anchoring device as well as the stem can be made of any material, however preferably of titanium or stainless steel or any biocompatible metal or metal alloy or plastic material. As biocompatible alloy, a NiTi alloy, e.g. Nitinol, can be used. Other materials can be magnesium or magnesium alloys. Biocompatible plastic materials that can be used are, for example, polyether ether ketone (PEEK) or poly-L-lactic acid (PLLA). The components can be made of the same or different materials from each other.

[0072] Reference will be made to Figures 19a to 20c The mounting of the head to the shank will be described. It should be noted that the bone anchoring element can be used in many applications, so that the assembled bone anchoring element can be inserted as a whole into a receiving part of, for example, a polyaxial bone anchor or a bone plate with locking screws. As shown, first, the head 3 is oriented so that the counter engagement portion 34 of the head 3 and the engagement portion 24 of the shank 2 face each other and the recess is rotationally aligned Figure 19a and Figure 20a ). Then, the head 3 is pressed onto the engagement portion 24 of the shank 2 so that the lower portion of the head 3 in the area of the recess 34 expands to let the engagement portion 24 in Figure 19b and Figure 20b ). Then, the engagement portion 24 moves within the recess until it abuts at the shoulder 34a of the recess 34 by the end surface 2a and the counter engagement portion 34 closes around the engagement portion 24. Due to the form-fit engagement of the engagement portions of the shank and the head, the head 3 is now rotationally fixed. In axial direction, the shank 2 can be held within the recess to some extent by friction.

[0073] The steps of assembling the receiving part 5 together with the pressure member 6 and the head 3 are shown in Figures 21a to 21e . As shown in Figures 21a to 21c , the head 3 is inserted into the pressure member 6 through the first front end 3a from the second end 6b of the pressure member 6 until the protrusion 68 of the pressure member 6 engages the groove 33 of the head 3. Thus, the protrusion 68 and the groove 33 provide a retaining structure for retaining the pressure member 6 and the head 3 together. Once assembled, the pressure member 6 and the head 3 are inserted into the receiving part 5 from the first end 5a with the second end 3b of the head 3 facing the opening 51. The stem recess 54 of the receiving part 5 and the stem recess 65 of the pressure member 6 are aligned.

[0074] During insertion of the pressure member 6 with the head 3 assembled therewith, the legs 62 of the pressure member 6 are slightly compressed towards each other when the outer rim 63 abuts against the crown of the inner thread 56 of the receiving part 5. When the outer rim 63 is at the threaded crown immediately above the slot 58, the elongated hole 64 overlaps the through hole 57 and the pin 4 can be inserted, as Figure 21eThe pin 4 also forms a fixing structure preventing the pressure member from rotating in the receiving part. In this position, the head 3 is in the accommodation space and has not yet entered the seat 52. This is the insertion position, defined at the uppermost position of the pressure member 6, in which it abuts against a stop provided by the pin 4, through the lower end of the elongated hole 64. There is still enough space between the outer spherical surface 30 of the head 3 and the seat to allow the lower part of the head 3 to expand, to allow the insertion of the engagement portion 24 of the handle 2. The head can slightly protrude from the opening 51.

[0075] Reference is made to Figures 22a to 22d , showing the mounting of the pre-assembled receiving part with the pressure member 6 and the head 3 to the handle 2. In Figure 22a , the engagement portion 24 of the handle 2 and the receiving part 5 are rotationally aligned relative to each other, so that the engagement portion 24 of the handle 2 can be inserted into the recess of the mating engagement portion 34 of the head 3 Figure 22b . Since the lower part of the head 3 is flexible, it can expand to allow the entry of the engagement portion 24. The pin 4 prevents the pressure member 6 from moving upwards during the insertion step. Figure 22c shows the step in which the engagement portion 24 has been completely inserted into the recess of the mating engagement portion 34 until it abuts against the shoulder 34a.

[0076] Finally, as shown in Figure 22d , the pressure member 6 is moved towards the second end 5b of the receiving part, so that the head 3 comes into contact with the seat 52 of the receiving part and is supported there. At the same time, the outer edge 63 snaps into the groove 58. The upper surface 58a of the groove provides an abutment for the upper surface 6a of the pressure member at the leg 62, so that the head 3 is held in the seat 52. The spherical recess 67 of the pressure member contacts a part of the upper part of the head 3, so that the head 3 can be held in this position by friction. Depending on the dimensions of the parts, this frictional holding of the head 3 can be stronger or weaker. Preferably, it is such that the frictional force can be overcome manually to pivot the receiving part 5 relative to the head 3 and the handle 2. At the same time, the lower part of the head 3 is compressed in the seat 52, so that it firmly holds the engagement portion 24 of the handle.

[0077] As shown in Figure 23a , when the receiving part 5 is pivoted relative to the handle 2, the protrusion 68 moves away from the groove 33 and allows the head 3 to pivot in the spherical seat 52 held by a part of the spherical recess 67. When the pivoted position of the handle 2 relative to the receiving part 5 changes to a zero angle position, i.e. a position in which the handle axis is coaxial with the central longitudinal axis C of the receiving part, the protrusion 68 snaps into the groove 33, thereby producing an audible or tactile feedback indicating the reaching of the defined position, in this case the zero angle position.

[0078] Once the desired angular position has been found, the rod 100 is inserted until it rests on the support surface 65 of the pressure member 6. As shown in Figure 23b The fixation member 7 is inserted between the legs 55 of the receiving member and is tightened so that it exerts a pressure on the rod and via the pressure member on the head to lock the angular position of the head relative to the receiving member. The fixation member can have protrusions 71 for pressing on the rod while the legs 62 are not in contact with the fixation member.

[0079] In a clinical application, at least two bone anchoring devices are inserted into the bone and connected by a rod. The bone anchoring devices offer a number of options for use. For example, the shank 2 can already be inserted into the bone and the pre-assembled receiving member 5 with the pressure member 6 and the head 3 can be installed in situ onto the engagement portion of the shank. In another option, in a configuration where the head 3 and the pressure member 6 are pre-assembled with the receiving member 5, the head can be installed to the shank 2 before the shank is inserted into the bone. Both options are useful in case the shank is a large diameter shank that cannot be guided through the opening 51. If a shank with a small outer diameter is used that allows the shank to be guided through the opening 51, the head 3 and the shank 2 can also be pre-assembled and guided through the receiving member 5 from the top end of the receiving member until the head 3 rests in the seat 52 as shown in Figures 19a to 20c

[0080] It should be noted that various shanks can be used and connected to the head and the receiving member so that the bone anchoring device can provide a modular system that allows the use of many different shanks in combination with the head and the receiving member.

[0081] In case the receiving member with the pressure member and the head is installed on the shank before the shank is inserted into the bone, the engagement portion 24 of the shank 2 provides a drive structure for engagement with a drive tool. Because the engagement portion is relatively large, a high torque can be applied. On the other hand, once the bone anchoring device has been fully assembled as shown in Figure 22d Figure 22d

[0082] Figure 24 A modified embodiment of the bone anchoring device is shown that is similar to the one shown in Figures 1 to 23b ​​​The difference in the first embodiment shown is that it allows the bone anchoring element to pivot to one side relative to the receiving member at a maximum angle greater than the opposite side. The receiving member 5000 has a lower end 5b', in which the plane P defined by the opening 5100 extends obliquely relative to the central axis C. This can be manufactured, for example, by cutting the end portion of the receiving member at an angle. The seat portion 5200 for the head increases axially so that it provides sufficient support surface for the head 3 in the region with an increased pivot angle. Figure 24 As shown, the bone anchoring element 1 pivots to one side at a larger maximum angle, which can be limited by the abutment of a portion of the handle at the lower end 5b' of the receiving member. It should be noted that other geometries of the receiving member and / or handle can be provided, which allow the handle to pivot at a larger maximum angle in one or more directions than in other directions.

[0083] Modular systems can also be provided using different headers. For example... Figure 25 As shown, in addition to the head 3 described above, another head 3' with a different drive structure can be combined with the handle 2. Therefore, since the bone anchoring device opens up various options for assembly and use, such options can be further expanded by adding various heads with different characteristics (such as different drive structures, different materials, different flexibility or other properties) for selective combination with the handle.

[0084] Figure 25 The head 3' shown includes... The drive structure 31' is the same as or similar to the drive device. Depending on the size of the drive structure 31', it can be used interchangeably with the receiving component 5 and pressure member 6 of the first embodiment, along with the head 3.

[0085] The head 3' can also be a bone anchoring device, such as Figures 26 to 37c This is a part of the second embodiment shown. Identical or highly similar components and parts are labeled with the same reference numerals as in the first embodiment, and their description will not be repeated. The bone anchoring device includes a bone anchoring element 1' having a handle 2 as in the first embodiment or another handle, a head 3', and a receiving member 5'. It differs from the first embodiment in that it does not require a pressure member, allowing the rod 100 to directly transmit the pressure applied by the fixing member 7 to the head 3'.

[0086] refer to Figures 28 to 31The head 3' is substantially solid in the upper portion and has an outer spherical surface 30a in the upper portion, which has a radius that can be the same as the radius of the spherical outer surface 30 of the lower portion. In other words, the head 3' can have a complete outer spherical surface, except at the second end 3b, which can be substantially flat. In the upper surface 30a, a drive structure 31'is provided in the form of a slot 31a', which forms a wing or lobe issuing in a curved manner from a center coinciding with the apex, i.e. the highest point on the spherical upper surface 30a. In more detail, the slot 31a forms four wings 36, which are all curved toward the same side and have the same shape and size and regular distance. Such a design is known as Drive. Each wing of the slot comprises a substantially straight or slightly inclined segment 36a and a circular segment 36b, where the two segments are connected at the end of the wing. The slot 31a' is open toward the outer surface at the end of the wings 36, as can be seen in particular in Figure 28 This drive structure is configured to deliver a high torque, like various other drive structures. The slot 33 and the engagement portion 34 are the same as in the first embodiment. To enhance the flexibility of the head 3', a second central recess 37 can be present after the engagement recess 34 in the direction toward the spherical upper surface 30a, which has a smaller inner diameter, so that a shoulder 34a is formed. The slit 35' can end at a distance from the slot 33 and can continue to an inner transverse slit 35a, also to increase the flexibility. However, the slit 35 and the central recess 37 cover the area of the head 3 having the largest outer diameter E, so that the head 3' is slightly compressed as a whole toward the central axis C.

[0087] Reference is made to Figures 32 to 35bThe receiving part 5' has a housing space 500 for the head 3' in which the head 3' can assume an insertion position and a final position for pivoting. To achieve this, the housing space 500 comprises near the second end 5b a lower seat 52', more specifically a hollow spherical segment portion, the radius of which matches the radius of the lower outer spherical surface 30 of the head 3'. The height of the lower spherical seat 52' is such that when the head 3' rests in the lower seat 52' by the spherical outer surface 30, the lower seat 52' extends slightly over the maximum outer diameter E of the head 3'. In this way, the head 3' is held in the pivoting position within the lower seat 52' by friction. This prevents the head 3' from being inadvertently pushed out of the lower seat 52' when the head 3' is in the pivoting position and the stem and the securing member have not yet been inserted and secured. The lower seat 52' can widen towards the second end 5b by a small section 52a' in order to facilitate the insertion of the head 3'. The opening 51' at the second end 5b has a size such that the head 3' can be introduced from the second end by slightly compressing the head 3'. In addition, the housing space 500 comprises an upper seat 520 which is separated from the lower seat 52' by a circumferential inner groove 510, the diameter of which is greater than the maximum diameter E of the head 3'. The inner groove 510 allows the head 3' to pass from the upper seat 520 into the pivoting position in the lower seat 52'. The upper seat 520 has a spherical shape which matches the spherical shape of the outer surfaces 30a, 30 of the head 3' and is configured to receive such outer surface portions of the head 3' which extend from the groove 33 to a certain extent below the maximum diameter E when the head is in the upper seat 520. Since the head 3' is compressible to a certain extent, it can be held in the upper seat 520 by friction. At the end of the upper seat 520 which faces the first end 5a, an annular inner protrusion 521 is formed which narrows the passage 50'. The protrusion 521 is configured to engage the groove 33 when the head 3' is in the upper seat 520. Moreover, the protrusion 521 can have a flat bottom surface facing in the direction of the second end 5b to form a stop when engaging the groove 33 of the head 3'. By means of the circumferential protrusion 521, an insertion position for the head is defined. From the protrusion 521, the passage 50' can widen to a region with a substantially constant diameter.

[0088] In this embodiment, the diameter of the inner thread 56 can be increased compared to the first embodiment to receive a somewhat larger securing member. The slot in the inner wall below the thread as in the first embodiment is not necessary, since this embodiment lacks a pressure member. It should be noted that the recess 54' for receiving the rod 100 has a passage diameter which substantially corresponds to the diameter of the rod or is only somewhat larger, so that the rod 100 is guided in the recess 54'. The dimensions of the accommodation space 500 and the depth of the substantially U-shaped recess 54' are such that when the head 3' rests in the pivoted position in the lower seat 52', the apex of the upper spherical surface 30a is above the bottom of the substantially U-shaped recess 54' in the axial direction, so that it can be engaged by the bottom surface of the rod 100 to exert a pressure on the head 3', for example as shown in Figure 37b and Figure 37c .

[0089] The assembly of the head 3' and the receiving member 5' is illustrated in Figures 36a to 36d . First, as shown in Figure 36a , the head 3' is oriented so that the upper spherical surface 30a faces the opening 51' of the receiving member 5'. Then, the head 3' is introduced through the opening 51' into the accommodation space 500. To achieve this, the head 3' is slightly compressed so that it can pass through the opening 51'. As shown in Figure 36b , the head 3' can enter the upper seat 520 until the annular protrusion 521 engages the lower part of the slot 33, thereby preventing further upward movement. This is the insertion position of the handle. The head 3' is additionally retained in the upper seat 520 by friction so that it cannot move away from the insertion position to the pivoted position by itself. Thereafter, as shown in Figure 36c , the handle 2 can be inserted with the engagement portion 24 expanding the lower part of the head 3' to enter the recess of the counter engagement portion 34. Finally, the engagement portion 24 of the handle 2 abuts against the stop 34a and the handle 2 is retained within the head 3' by friction, as depicted in Figure 36d . Due to the stop provided by the annular protrusion 521, the head is prevented from moving away from the receiving member in the direction towards the first end 5a during insertion of the handle.

[0090] With reference to Figures 37a to 37c , once the receiving member 5' with the head 3' is mounted to the handle 2, the head 3' is moved away from the insertion position into the lower seat 52'. Since the protrusion 521 is rounded towards the first end 5a, it can easily move away from the slot 33. In Figure 37a , the axis of the handle 2 and the central longitudinal axis C of the receiving member 5' are coaxial. Then, as shown in Figure 37b , the receiving member 5' can be pivoted relative to the handle 2 and can be retained in such a pivoted position by friction in the lower seat 52'. Finally, asFigure 37c As shown in Fig. 6, the shaft is inserted into the substantially U-shaped channel 54' and the fixation member 7 is screwed between the leg portions 55 of the receiving member 5'. When the fixation member 7 is tightened, it presses against the shaft and the shaft 100 in turn presses against the spherical surface 30a of the head 3' to lock the shaft and the head.

[0091] It should be noted that, as in the first embodiment, in clinical use, the shank can first be inserted into the bone and the pre-assembled receiving member 5' with the head 3' can be mounted onto the shank, or alternatively, the bone anchoring device comprising the shank 2, the head 3' and the receiving member 5' is pre-assembled and then inserted into the bone. In any case, the tool can access the drive structure 31' through the channel 50' and the drive structure provides a large drive surface for the application of high torque.

[0092] Modifications of the above-described embodiments are possible. While the receiving member and the pressure member are shown as one-piece members, they can also be made of two or more pieces. For the shank, various shanks can be used, such as a partially threaded shank, a nail, a hollow shank and various other shanks. It is contemplated that the engagement portion of the shank comprises a recess and the counter-engagement portion of the head comprises a protrusion that engages the recess of the shank. Various other drive structures for the engagement portion of the shank or the drive structure of the head can also be implemented.

[0093] The position indicating structure can be designed to indicate predetermined angles other than zero degrees.

[0094] The pressure member can have leg portions extending above the shaft so that a two-piece fixation member can be used. For example, in such a two-piece fixation member, an inner fixation member acts on the shaft and an outer fixation member acts on the leg portions of the pressure member.

[0095] While the shaft is shown as a cylindrical shaft, it is contemplated that the shaft can have any other cross-section. The shaft support surface can be cylindrical or flat, or have any other suitable profile for supporting the shaft.

[0096] In addition, particular features, structures, or characteristics of one embodiment can be combined with particular features, structures, or characteristics of another embodiment in any suitable manner to produce further embodiments. The particular shapes of the elements are not limited to the particular shapes shown in the drawings, but can vary.

Claims

1. A bone anchoring device, comprising: Anchoring element (1, 1'), the anchoring element comprising: A handle (2) for anchoring in bone, the handle (2) comprising a first end (2a) and an opposing second end (2b), and Head (3, 3'), the head having an outer surface (30) with a spherical portion; The handle (2) and the head (3, 3') are separate components configured to connect to each other; and The handle (2) includes an engagement portion (24) at the first end (2a) for engaging the head, and the engagement portion (24) is configured to be engaged by a drive tool. and The head (3, 3') includes a first end (3a) containing a drive structure (31, 31') for engaging with a drive tool, and the head includes an opposing second end (3b) including a mating engagement portion (34) for engaging with the engagement portion (24) of the handle.

2. The bone anchoring device according to claim 1, further comprising a receiving member (5, 5') having a receiving space (50; 500) for pivotally receiving the head (3, 3'), wherein the head (3, 3') is connectable to the receiving member (5, 5') prior to connection to the handle (2).

3. The bone anchoring device according to claim 2, characterized in that, The receiving component (5, 5000, 5') includes an opening (51, 51') configured to allow at least a portion of the handle (2) to extend through the opening for connection to the head (3, 3').

4. The bone anchoring device according to claim 3, characterized in that, The handle (2) includes a maximum outer diameter smaller than the width of the opening (51, 51'), or alternatively, the handle (2) includes a maximum outer diameter larger than the width of the opening (51, 51').

5. The bone anchoring device according to claim 2 or 3, characterized in that, The head (3, 3') is configured to take an insertion position in the receiving member (5, 5000, 5'), in which the handle can be connected to the head (3, 3') along the insertion direction, and wherein the head (3, 3') is directly or indirectly fixed by a stop to prevent axial movement along the insertion direction.

6. The bone anchoring device according to claim 2 or 3, further comprising a pressure member (6) configured to transmit pressure applied by the fixation member (7) to the head (3) to lock the head in the receiving space.

7. The bone anchoring device according to claim 6, characterized in that, The pressure member (6) at least partially surrounds the head (3), and the pressure member (6) includes a protrusion (68) that releasably engages a recess in the head to temporarily attach the head (3) to the pressure member (6).

8. The bone anchoring device according to claim 7, characterized in that, The protrusion (68) is configured to engage the head (3) only in a predetermined pivot position relative to the pressure member (6).

9. The bone anchoring device according to claim 2 or 3, characterized in that, The drive structure (31) includes a recess with a star-shaped profile.

10. The bone anchoring device according to claim 9, characterized in that, The star-shaped outline has a plum blossom-shaped structure.

11. The bone anchoring device according to claim 9, characterized in that, The recess of the drive structure extends substantially across the entire free end surface of the head (3).

12. The bone anchoring device according to claim 2 or 3, characterized in that, The head (3') is configured to be locked directly into the accommodating space (500) by the action of the fixing member (7).

13. The bone anchoring device according to claim 2 or 3, characterized in that, The head (3) includes a circular free end surface on the side opposite to the handle (2), and the drive structure (31') includes a groove in the shape of a plurality of curved wings (36) arranged around the center of the free end surface and emanating from the center of the free end surface.

14. The bone anchoring device according to claim 5, characterized in that, In the insertion position, the head (3') is additionally held in the receiving member (5') by friction.

15. The bone anchoring device according to claim 2 or 3, characterized in that, The accommodating space (50; 500) includes a seat for directly supporting the head (3, 3') to allow the head to pivot.

16. The bone anchoring device according to claim 15, characterized in that, The size of the head (3') relative to the seat is configured such that the head (3') is held within the seat by friction.

17. The bone anchoring device according to claim 1 or 2, characterized in that, The head (3, 3') includes a central longitudinal axis (C), and the head (3, 3') is compressible toward the central longitudinal axis in at least a portion of the head.

18. The bone anchoring device according to claim 2 or 3, characterized in that, The head (3') is configured to be locked directly into the accommodating space (500) via a single intermediate component in the form of a rod.

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