Bone anchoring device for pedicle access

Description

[0001] In structurally weakened spines, fixation with bone anchors can pose a biomechanical problem, namely that the bone is not sufficiently load-bearing for adequate anchorage with pedicle screws or similar devices. For these cases, augmentation with bone cement of the vertebra is considered state-of-the-art. A viable alternative to pedicle screws with bone cement is not currently available.

[0002] Bone cement is based on polymethyl methacrylate (PMMA). It is mixed together from two components during surgery and is ready for use in just a few minutes. During application and injection, higher temperatures arise during curing, so the risk of tissue overheating cannot be ruled out. This can lead to necrosis. Furthermore, there is an active risk of triggering a life-threatening embolism during injection, e.g., if liquid PMMA enters the bloodstream and hardens. Accidental contact with PMMA of other critical structures (e.g., dura or nerve roots) is also possible and therefore carries a risk. Once injected, the hardened PMMA plastic can no longer be removed from the bone. These make revision surgery more difficult, so it would ultimately be better to avoid bone cement.

[0003] US5300074A describes a concept for treating femoral fractures in which a helical blade is used for rotationally stable fixation of a femoral head fracture. WO9805263A1 presents a similar concept, but further biomechanical advantages of a blade-like implant are discussed. The descriptions and illustrated structures in both documents reveal another biomechanical advantage. The distally directed plate in the femoral head, angled at approximately 90°, is rotated precisely in the direction of load, generating maximum bone surface contact in the direction of load. This fixation method is therefore particularly suitable for structurally weaker bones.

[0004] A blade-like bone anchor for stabilizing spinal segments was designed for anterior or anterolateral access (WO0245606A1). However, the bone anchor presented therein is not suitable for posterior access through a pedicle canal. The applicant requires a specific insertion orientation for this bone anchor, which is unsuitable for implantation into the pedicle canal. It is postulated that the distal blade orientation of the bone anchor is aligned parallel to the medial-lateral or distal-proximal plane and then implanted into the vertebra. However, this orientation does not allow implantation into a pedicle canal, as this has a different main orientation. Furthermore, the structure presented therein is multi-part, which has an adverse effect on fatigue strength.

[0005] WO 98 / 52482 A1 discloses a device for fixating bones, in particular vertebral bodies, relative to one another, comprising a longitudinal beam 1 with a central axis 2 and anchoring elements 3 with longitudinal axes 4, each with a front end 5 and a rear end 6, wherein the longitudinal axes 4 of the anchoring elements 3 are at an angle of between 65° and 115° to the central axis 2 of the longitudinal beam 1. At least one of the anchoring elements 3 is blade-shaped, wherein the anchoring element 3 comprises, at the rear end 6, receiving means 7 for the longitudinal beam 1 with locking means 8, 13 for releasably fixing the connection between the longitudinal beam 1 and the anchoring element 3, and the fixed connection does not permit any relative movement between the longitudinal beam 1 and the anchoring element 3.

[0006] EP 2 740 428 A1 discloses a dynamic bone anchor comprising an anchor element with a tubular body defining an anchor axis. The anchor element comprises a plurality of barb elements, each barb element being movable between a first position adjacent a surface of the tubular body and a second position farther from the surface of the tubular body than the first position. At least a portion of a free cutting edge of the barb elements is inclined at an angle corresponding to a helix angle extending over at least one full revolution around the anchor axis. A longitudinal core element is provided in the tubular body and has a first portion not connected to the anchor element, such that the anchor element is movable relative thereto.

[0007] US 2012 / 143266 A1 discloses a polyaxial bone screw assembly comprising a threaded shaft body with an integrated upper portion that can be received within an integrated receiver, the receiver having an upper channel for receiving a longitudinal connecting element and a lower cavity that cooperates with a lower opening. A friction-fit compression insert, a planar, split retaining ring, and an upper shaft portion cooperate to enable slip-on or snap-in assembly of the shaft with the receiver either before or after implantation of the stem into a vertebra.

[0008] WO 98 / 51241 A1 discloses a device for implanting reinforcing bars and a method for using the same. The reinforcing steel devices in question have a flat surface with at least one protrusion having a substantially continuous cross-sectional profile. The radius of curvature at any point of the cross-sectional profile is between approximately 0.1 mm and 10 mm. The reinforcing bar devices in question are used in numerous orthopedic and related applications, including interfragmentary fixation, the attachment of soft tissue to bone, or the attachment of plates or nails to bone, and the like.

[0009] US 2010 / 331895 A1 discloses an osteosynthetic device for fixating a bone or bone fragments, which has a longitudinal axis and comprises a bone screw with a shaft having a thread, a front end, and a rear end, wherein the thread has a maximum outer diameter. Furthermore, the device has a wing-like blade, the front end of which is connected to the front end of the bone screw and the rear end of which is connected to the rear end of the bone screw. The blade is also provided with a coaxial longitudinal opening having a length extending between the front end and the rear end. Furthermore, the blade is coaxially and rotatably mounted on the shaft of the bone screw.

[0010] The bone anchoring device according to the invention is intended to offer an alternative to cement-augmented pedicle screws, especially when the internal bony structure of the vertebra is weakened due to osteopenia or even osteoporosis. Furthermore, the method of insertion is intended to simplify and accelerate the work with pedicle anchors for the surgeon.

[0011] This object is achieved according to the invention by a bone anchoring device for anchoring and fixing vertebrae, in particular for insertion into a pedicle canal according to claim 1. The bone anchoring device further comprises a fork head, which in a side view is U-shaped, for a correction element, in particular a connecting rod, with two legs that taper proximally and form a threaded portion that engages with an adjusting means, wherein the legs have a radially outer circumferential region in which at least one retaining groove or other instrument attachment point is formed for gripping the fork head by means of a handling instrument, and a bone anchoring element with a spherical head, and the bone anchoring element is polyaxially pivotable relative to the fork head, and a pressure piece, wherein the pressure piece partially surrounds the bone anchoring element distally on the spherical head,and proximally forms a seat for the connecting rod, and the bone anchoring element is mounted from distal to distal with the fork head and with the pressure piece, characterized in that the bone anchoring element has a mainly cylindrical core, and the mainly cylindrical core at the proximal region increases in diameter at least in sections from distal to proximal, and two wings extend laterally, and the wings have a distal wing orientation and a proximal wing orientation different therefrom, and the wings form helically between these wing orientations and the bone anchoring element is designed not for screwing in, but for driving into the bone.

[0012] The structure, a helical arrangement of two wings arranged around a predominantly cylindrical core, offers the advantage that the bone anchoring element is rotationally stable in the bone. Conventional pedicle screws are not. This means that the inventive design also allows corrective rotational moments to be introduced into the bone, something that was not possible with previous pedicle screws.

[0013] If the bone anchoring element with the fork head is fixed to a connecting rod using an adjusting device, such as a grub screw, the polyaxial pivotability of the fork head is also deactivated. Due to the rotational stability in the bone and the deactivated polyaxiality, such a bone anchoring element is pull-out-resistant in the bone. A pull-out movement would force a rotation of the bone anchoring element. This rotation is not possible due to the connection of two or more bone anchoring devices along a connecting rod. Two or more bone anchoring devices along a connecting rod hold the connecting rod rotationally fixed around the anchor points, and as a result, the bone anchoring element remains tensile-resistant in the bone.

[0014] Additional teeth are advantageous for increasing the pull-out strength in the bone. These teeth are preferably located in the pedicle region so that they can lock into the bone or the inner wall of the pedicle, thus ensuring optimal effectiveness against any pull-out movement of the bone anchoring element. For locking purposes, it is advantageous for the teeth to be arranged on at least one elastic tongue. With the help of the spring-elastic tongue, the teeth can move into the interior of the core during insertion of the bone anchoring element. They are deformed inward by the bony structure. After insertion of the bone anchoring element into the pedicle canal, the tongues can be returned to their original position using a sleeve element. This results in the teeth being pressed into the inner wall of the pedicle canal. The bone anchoring element is then locked into the bone in the pedicle region.It is also advantageous if the teeth are arranged laterally, i.e., they engage the pedicle canal medially and laterally. Only there do they have contact with the cortical layer of the pedicle canal.

[0015] To further increase pull-out strength, it is advantageous if the core has one or more circumferential grooves with a hook- or barb-like profile in the circumferential direction. This simplifies insertion and makes withdrawal more difficult. It is advantageous if the circumferential grooves are not partially formed, but fully formed. They traverse the lateral wings and contribute to the porosity of the wings.

[0016] Porosity in the winglets is extremely beneficial for the success of the implant if it is to function without additional bone cement. Bone cells grow more slowly, and the associated metabolism is disrupted in solid-material implants. Therefore, a porous structure is very advantageous. Preferably, a porosity of the winglets should be chosen that is known to promote bone cell growth and proliferation. This ranges from 0.2 mm to 2.0 mm, with an optimal range of 0.4 mm to 0.8 mm.

[0017] In order for the bone anchoring element according to the invention to become a functional unit, i.e. a bone anchoring device, it must be mounted with a fork head. Since the lateral wings have a certain width, such a bone anchoring element cannot be guided into the fork head and mounted from the proximal side. The bone anchoring element must be inserted and mounted from the distal side into the fork head in order for the bone anchoring device to function as an implant. There is extensive prior art for this type of fork head assembly on bone anchors from the distal side. As an example, and not further detailed, a slotted pressure piece is shown, which is guided into the fork head from the distal side and then the ball head of the bone anchoring element can be clicked into the pressure piece from the distal side. If a force is now applied, e.g.By tightening an adjusting device (grub screw) and connecting rod, this force also acts on the thrust piece. The thrust piece is pressed around the ball head by an outer conical surface of the thrust piece and a congruent inner surface of the fork head. The force generated by the adjusting device fully clamps the fork head and fixes the polyaxiality.

[0018] The bone anchoring element is characterized by two lateral wings along the core. These wings have a helical shape around the core's central axis. A pitch of between 100 mm and 300 mm is provided, in particular 150 mm and 250 mm, and in particular 160 mm and 200 mm. Ideally, the entire range of bone anchoring devices has the same pitch so that if a bone anchoring device with a different length or diameter needs to be replaced, the same pre-prepared bone channel can be used. Across all lengths of the bone anchoring device set, the rotation of the helical outer wings is 60° to 120°, in particular 70° to 110°, and in particular 80° to 100°. Furthermore, it is advantageous if a range of bone anchoring devices with different lengths and diameters have the same form factor.

[0019] Preferably, the bone anchoring element is configured to allow implantation of the bone anchoring device by ensuring that the wing orientation of the distal end of the bone anchoring element corresponds to the main orientation of the pedicle canal. This corresponds almost to a craniocaudal orientation. The bone anchoring element is driven into the pedicle canal by impact. The bone anchoring element rotates around the central axis according to the previously defined pitch. In the final position, the distal wing orientation has a lateral-medial orientation, with the proximal wing orientation corresponding to the main pedicle orientation.

[0020] After implantation, the bone anchoring element is located in the vertebra. The bone anchoring element is further designed such that the proximal outer surfaces of the wing rest on the cranial and caudal regions of the pedicle canal, or they point in these directions. Distally, the projected surface, created by the core and the lateral wing surfaces, rests in the cancellous bone of the vertebra in a cranial / caudal direction. This prevents tilting of the bone anchoring device, which could trigger a flexion / extension movement. The bone anchoring device rests optimally on the bony structures, or at least points in this direction, and distributes the resulting load more evenly and broadly to the cancellous bone tissue than a pedicle screw.Likewise, the bone anchoring device is supported proximally in the predominantly oval-shaped pedicle canal cranially and caudally, or it points with its outer wings in this direction. Other pedicle screws, as cylindrical objects in an oval tunnel (=pedicle canal), are not biomechanically optimal.

[0021] To prevent the outer surfaces of the wings from pressing into or even cutting into the caudal and cranial areas of the pedicle region at the proximal area, it is advantageous if the outer surfaces of the wings have convex curvatures in order to reduce the contact stresses to the cranial and caudal pedicle areas.

[0022] For better load distribution of the bending moment along the bone anchoring element, it is advantageous for the two wings to taper in the proximal area toward the ball head and end at the outer contour of the core. Furthermore, the core can be tapered in sections in the proximal area, more specifically in the neck area. This also better distributes the bending moments and stresses within the loaded component.

[0023] Naturally, pedicle canals have a certain shape factor that describes the oval. This shape factor defines the relationship between height and width. Ideally, the bone anchoring elements according to the invention are precisely adapted to best reflect the oval cross-section. The bone anchoring elements, with their two wings, have a height (H) defined between the outer edges of the wings, and an outer diameter (D) of the core (including teeth), a shape factor with a ratio of H / D that is between 1.3 and 2.5, preferably 1.4 and 2.2, and preferably 1.6 and 2.0.

[0024] Cannulation with lateral openings is advantageous for additional strength gains and, as a last resort if bone quality is too low, is used. Bone cement can be injected through these openings. The advantage here is that the orientation of the lateral openings after implantation always points cranially and caudally, where the greatest load within the cancellous bone is directed. Furthermore, it is advantageous if the cannulation has different diameters. For example, a sleeve element can be inserted proximally.

[0025] Since the bone anchoring element according to the invention, as part of the bone anchoring device, is a relatively complex geometric structure, it is advantageous if the bone anchoring element is manufactured in one piece using a generative manufacturing process. This includes all known 3D printing processes, such as laser beam melting, electron beam melting, or other additive processes. Suitable materials are all implantable materials, such as titanium, CoCr or stainless steel alloys, or plastics such as PEEK, PSU, PPSU, PEAK, PEK, fiber-reinforced CFR-PEEK, etc. Furthermore, it can be advantageous if geometric structures with tight tolerances, such as the ball head, are subsequently reworked using a machining process (e.g. CNC turning, CNC milling or eroding).

[0026] Further features and details of the invention emerge from the patent claims, the following figures and the following description of the illustrated embodiments of the bone anchoring device according to the invention: Fig. 1 shows the bone anchoring device according to the invention in assembly and in an exploded view. Fig. 2 shows the bone anchoring device according to the invention mounted with a connecting rod and an adjusting device. This is in assembled and exploded view. Fig. 3 illustrates two implanted bone anchoring devices in a vertebra. Fig. 4a shows the bone anchoring device before entering the pedicle canal. Fig. 4b shows the bone anchoring device in its final position after implantation. Fig. 4c shows a cross-section through a pedicle canal with an implanted bone anchoring device. Fig. 5 shows the vertebra with two implanted bone anchoring devices in three views. Fig. 6 compares a conventional screw shaft of a bone screw, as used in a pedicle screw, with the bone anchoring element according to the invention. Fig. 7 shows the corresponding projected areas that cause the load distribution on the bone tissue. Fig. 8 different cuts through the bone anchoring device. Fig. 9a und Fig. 9b depict the bone anchoring element according to the invention, which has teeth for locking in the pedicle canal, and the sleeve element, which presses the elastic tongue with the teeth towards the inner pedicle wall. Fig. 10a und b each show a bone anchoring element, with the elastic tongue pointing proximally in one case and distally in the other case. Fig. 11a und 11b show a bone anchoring element with a rotatably mounted bone thread section in the pedicle area. Fig. 12a und b also present a variant that has a rotatably mounted bone thread section. Fig. 13 shows a bone anchoring element in which the outer surfaces of the wings have convex curvatures so that no stress concentrations occur on the cranial and caudal pedicle inner wall. Fig. 14 illustrates a bone anchoring element in which the opposing wing surfaces are not parallel, but rather thicken toward the core. This has a positive influence on the flexural stability of the wings.

[0027] Fig. 1 and 2show the bone anchoring device (1) according to the invention, consisting of a fork head (90), a bone anchoring element (10), and a pressure piece (91). The bone anchoring element (10) defines a central axis along the length (412), which extends from distal (40) to proximal (41). The bone anchoring element (10) has, from proximal (41) to distal (40), a spherical head (100), a neck region (110), a pedicle region (120), core (140), and a distal region (130). Two wings (150, 151) are arranged laterally along the central and mainly cylindrical core (140). The wings each have a wing orientation proximally (441) and distally (440) that is different from one another. Along these two wing orientations (440 and 441), the wings form a helix according to a greater pitch. Details of the climb are previously revealed.The bone anchoring element (10) is held by a pressure piece (91) which partially encloses the ball head (100) and receives it in a seat (910). This seat (910) is elastically deformable in that spring arms (911) are formed by corresponding slots (912). On the outside, the pressure piece has a conical surface (914) which is in contact with the opening (930) of the fork head (92). Once finally assembled, the pressure piece (91) is located in the fork head (90). The pressure piece (91) has a seat (913) proximally for a connecting rod (70). This seat (913) is aligned with the fork head (90) in such a way that the U-shaped cutout (92) corresponds to it. The fork head (90) has two tapered legs (921 and 922) at the proximal area, which together form a threaded section (925) into which an adjusting means (80) with a congruent threaded section (81) can be screwed.For this purpose, the adjusting means (80) has a tool connection (82), which is not shown. Torx, multi-tooth, hexagon, square, and other suitable connection types are suitable for the tool connection (82). The fork head (90) has devices (926) on its outer proximal circumference, such as a retaining groove or recesses, which are suitable for attaching an instrument to it.

[0028] Fig. 3 and 5show a paired implantation of bone anchoring devices (1) in a vertebra (60). Various anatomical directions can be defined. Distal (40) and proximal (41) result from the previously mentioned definition. Laterally from this, the lateral (44) and medial (45) directions are defined, and perpendicularly from this, the cranial (42) and caudal (43) directions are defined. The vertebra (60) can be divided into regions important for the bone anchoring device (1) according to the invention: pedicle entry (61), pedicle canal (63), and the internal cancellous bone (62).

[0029] In Fig. 4a, b and c The process of implantation into the pedicle canal (63) is shown. The pedicle canal (63) has a cortical bone (631) and an inner cancellous area (632). Fig. 4a It can be seen that the distal end of the bone anchoring element (10) is guided into the pedicle entry (61). The pedicle canal has a section ( Fig. 4c ) an oval shape, with the longer extension of the oval oriented in the cranial-caudal direction (42, 43). This corresponds to the pedicle orientation (46). When inserting the bone anchoring element (10) into the pedicle entry (61), the surgeon must ensure that the distal wing orientation (440) corresponds to the pedicle orientation (46). After the bone anchoring element (10) has been impacted into the vertebra (60) ( Fig. 4b ), the proximal wing alignment (441) now corresponds to the pedicle alignment (46). This means that, viewed in section, the profile of the bone anchoring element (10) remains identical in the pedicle canal ( Fig. 4c ). The bone anchoring element (10) moves during implantation into the vertebral interior (62) along the predetermined helix, which is enforced by the wings (150, 151). In the fully implanted state, the distal wing alignment (440) is in a lateral orientation, ie, the wings (150, 151) point laterally and medially. Fig. 4c It is further shown that the bone anchoring element (10) approximates the oval region of the pedicle (63) quite well. Cranially (1506) and caudally (1516), the bone anchoring element (10) preferably has rounded outer surfaces that prevent cutting, indentation, or splitting of the cortical layer of the pedicle. The outer surfaces (1506, 1516) can extend beyond the lateral walls of the wings (1502, 1504 and 1512, 1514).

[0030] Fig. 6 shows a direct comparison of a conventional bone screw (20) and the bone anchoring element (10) of the bone anchoring device (1) according to the invention. The spherical head (100, 200) and neck region (110, 210) are structurally similar. Both bone anchors (10 and 20) have a core (140 and 240) and a distal region (130 and 230). The bone screw (20) has a bone thread (250), which simultaneously defines the outer diameter (D') of the bone screw. The core (240) corresponds to the inner diameter (d'). Analogously, the outer diameter (D) of the bone anchoring element (10) can be located based on the outer circumference of the teeth (122). Furthermore, the core diameter (d) can be defined by the core (140) itself. Thus, the diameters D'=D and d'=d correspond for a direct comparison.A clearly noticeable difference from the bone screw is that the bone anchoring element (10) features two wings: a first wing (150) and a second wing (151). They define a width (H). The ratio of the width (H) to the diameter (D) is defined as the form factor. The preferred ranges of the form factor have already been mentioned. It is advantageous if the width of the two wings (150, 151) gradually decreases towards the ball head (100) (1510) and ends in the core (140). This has a positive effect on the bending stress distribution.

[0031] Fig. 7a und 7b illustrate the direct comparison of the load-bearing projected areas (190, 290) in the cancellous bone (62) of a vertebra (60). Fig. 7a shows the projected area (290) of a bone screw (20) which is loaded during a flexion / extension movement within the cancellous bone. Fig. 7b shows the projected area of the bone anchoring element (10) according to the invention. It can be clearly seen that this area (190) is significantly larger than the area of a bone screw (290). The larger this projected area, the more load can be transferred to soft cancellous tissue. Overall, depending on the shape factor, this active load-bearing area can be almost doubled. In this direction of view, the advantageous course of an increase in diameter (111) between and / or at the pedicle region (120) and the neck region (110) can also be identified. This ensures that the neck region has sufficient flexural rigidity. The increase in diameter can be conical, partially conical, or based on curves.

[0032] Fig. 8 shows the bone anchoring device (1) according to the invention in two views as well as some sections orthogonal to the central axis (412). It can be seen that the wings (150, 151) have a different orientation. The cannulation (14) with the lateral fenestration openings (141) can be seen in the longitudinal section. The cannulation preferably has different diameters (142, 143). On the one hand, this is intended to increase fluid resistance at the distal end of the cannulation by reducing the diameter distally (142). On the other hand, it is advantageous if the cannulation (14) can simultaneously be used as a seat for a sleeve element (124). For this purpose, a diameter enlargement (143) can be provided. In a view of the bone anchoring device (1) it can be seen that the wings (150, 151) are characterized by a porosity or by several openings (1509, 1519).They serve to promote the growth and integration of bone cells. A preferred pore size has already been mentioned. Furthermore, it is advantageous if the core (140) has one or more circumferential grooves (149). These grooves have a hook-like profile. This improves the pull-out strength of the bone anchoring element (10) in the bone.

[0033] Fig. 9a und 9b show the bone anchoring element (10) using a sleeve element (124) which can be guided into the cannulation opening (14). Fig. 9a shows the state in which the elastic spring arms (121) with the teeth (122) located thereon can be deflected into the core interior. The elastic spring arms (121) are formed by one or more slots (123). U-shaped slots are shown here. After the sleeve element (124) is inserted into the cannulation (14) ( Fig. 9b ), the elastic spring arms (121) can no longer compress. They are prevented from doing so by the sleeve element body (124). Furthermore, inserting the sleeve element (124) actively displaces the elastic spring arms (121) from the cannulation area. Thus, with the aid of the sleeve element, it is possible for the teeth (122) to be pressed into the pedicle wall after implantation of the bone anchoring element (10). Ideally, the teeth (122) are located at the level of the pedicle area (120). In this area (120), they can achieve the best possible locking effect with the pedicle canal (63). Fig. 10a und 10b show a different direction in which the elastic spring arms can be arranged. Also in Fig. 9a und 9b An indicator (185) is shown, which serves to indicate the distal wing alignment (440) and / or proximal wing alignment (441) to the user. Asymmetrical shapes, slits, markings, or even labels can be used as indicators. Furthermore, it is advantageous if the indicator simultaneously serves as an interface for a surgical instrument, thereby indicating the orientation of the wing alignments (440, 441) away from the implant.

[0034] Fig. 11a und 11b show an alternative embodiment of a bone anchoring element (11). Here, the pedicle region (120) of the bone anchoring element (11) is cylindrically shaped. Mounted thereon is a rotatable partial threaded section (18), which has a bone thread (183), a ball head (181), and a tool engagement point (182). By initiating a rotation on the tool engagement point (182), the bone thread can be activated, thus achieving a bone screw-like anchoring in the pedicle region (120). This allows the advantages of a bone screw to be combined with a large-area distal support. The rotatable partial threaded section (18) is held by elastic hooks (126). Without a sleeve element (125), the elastic hooks (126) are flexible. For example, the rotatable partial threaded section (18) can be mounted quite easily by plugging it on.After inserting the sleeve element (125) into the cannulation (14, 143), the elastic hooks (126) are no longer movable and thus a loss protection is created.

[0035] Another alternative design is described in Fig. 12a und 12b A bone anchoring element (12) is shown which has a rotatable partial threaded portion (18). This threaded portion (18) is located in a designated opening (129). Here, too, the threaded portion (18) is connected in a rotationally fixed manner to a tool engagement point (182) via a rotatable sleeve element (127), but joined rather than in one piece. The ball head (181) is formed by the bone anchoring element (12) itself. It is arranged in a stationary manner compared to the rotatable sleeve element (127).

[0036] Fig. 13 shows a form of a bone anchoring element (10) in which the curves of the outer wing edges 1506 and 1516 are more prominently displayed. Convexly curved outer edge surfaces have the advantage that they do not cut into the bone and distribute loads more evenly. It can be advantageous for the width of the convexly curved outer wing edges to be greater than the width of the lateral wing surfaces (1502, 1504, 1512, and 1514).

[0037] Fig. 14 shows an advantageous embodiment of the bone anchoring element (10) according to the invention, in which the wings (150 and 151) are not parallel, but rather taper in cross-section toward the core (140). This results in bending stresses being distributed more evenly radially outward. Furthermore, it can also be seen here that the lateral surfaces of the wings (1502, 1504, 1512, and 1514) can be spaced closer than the convex outer edges (1506 and 1516).

Claims

1. A bone anchoring device (1) for anchoring and fixing vertebrae (60), in particular for insertion into a pedicle canal (63), with a fork head (90) having a U-shaped cutout (92) in a side view for a correction element, in particular a connecting rod (70) with two legs (921, 922) which terminate proximally (41) and form a threaded section (925) which engages with an adjusting means (80, 81), wherein the legs (921, 922) have a radially outer circumferential area in which at least one retaining groove or other instrument attachment point (926) is formed for gripping the fork head (90) by means of a handling instrument, and a bone anchoring element (10), with a proximal end facing away therefrom in the axial direction (412), such that a distal direction (40) and a proximal direction (41) are also defined, wherein the bone anchoring element (10) has a spherical head (100) at the proximal end area and the bone anchoring element (10) can be pivoted polyaxially with respect to the fork head (90), and the bone anchoring element (10) is mounted with the fork head (90) coming from the distal end, characterized in that the bone anchoring element (10) has a mainly cylindrical core (140), and the mainly cylindrical core (140) at the proximal area (110, 120) enlarges at least in sections (111) from distal (40) to proximal (41) and in that two wings (150, 151) extend laterally and the wings (150, 151) have a distal wing orientation (440) and a proximal wing orientation (441) different therefrom, and in that the wings (150, 151) form helically between these wing orientations (440, 441), and in that the bone anchoring element (10) is not formed for screwing in, but for hammering into the bone (61, 63) and in that, the bone anchoring element (10) is configured in such a way that after implantation into a vertebra, the outer surfaces (1506, 1516) of the wings at the proximal area point in the direction of the cranial and caudal areas of the pedicle canal (63) and distally (40), the projected area (190) that is formed by the core (140, 130) and the lateral wing surfaces (1502, 1504, 1512, 1514), is aligned in the cranial (42) / caudal (43) direction in the cancellous bone of the vertebra (62).

2. The bone anchoring device according to the preceding claim, characterized in that the two wings (150, 151) taper in width at the proximal area (1510) towards the spherical head (100) and open onto the outer contour of the core (140).

3. The bone anchoring device according to any one of the preceding claims, characterized in that the bone anchoring element (10) has a pedicle area (120) which has at least one resilient tongue (121) which results from a U-shaped slot (123), and in that the resilient mobility of this at least one resilient tongue (121) is inhibited by an insertable sleeve element (124, 125).

4. The bone anchoring device according to the preceding claim, characterized in that the resilient tongue (121) has one or more teeth (122), and in that these teeth communicate with the pedicle canal (63) in the pedicle area (120) and, after insertion of the sleeve element (124), lock into place with the bone.

5. The bone anchoring device according to any one of the preceding claims, characterized in that the bone anchoring element (10) with the two wings (150, 151) defines a height H between the outer edges of the wings (1506 and 1516), and an outer diameter D of the teeth (122), wherein the form factor, from the ratio H / D, is between 1.3 to 2.5, preferably 1.4 to 2.2, preferably 1.6 to 2.0.

6. The bone anchoring device according to any one of the preceding claims, characterized in that the bone anchoring element (10) has at least one circumferential groove (149) on the core (140), and in that the circumferential groove forms a hook- like profile which hooks with the bone in the pull-out direction.

7. The bone anchoring device according to any one of the preceding claims, characterized in that the outer surfaces (1506, 1516) in the section of the wings (150 and 151) have convex curvatures in order to reduce the contact stresses with respect to the cranial and caudal pedicle areas.

8. The bone anchoring device according to any one of the preceding claims, characterized in that the outer surfaces (1506, 1516) of the wings (150 and 151), in section transverse to the axis (412), are wider than the minimum distance between the wing surfaces (1502, 1504 and / or 1512, 1514).

9. The bone anchoring device according to any one of the preceding claims, characterized in that the lateral wing surfaces (1502, 1504, 1512, 1514) thicken towards the core (140) in section transverse to the axis (412).

10. The bone anchoring device according to any one of the preceding claims, characterized in that the wings (150 and 151) have several openings (1509, 1519) which have a pore size between 0.4 and 2.0 mm, preferably 0.5-1.0 mm, and in that these openings are hexagonal and are used as a whole for the growth of bones.

11. The bone anchoring device according to any one of the preceding claims, characterized in that the bone anchoring element (10) was manufactured with the aid of an additive manufacturing method, such as, for example, a 3D printing process, such as laser beam or electron beam melting, and in that the bone anchoring element (10) is in one piece.

12. The bone anchoring device according to any one of the preceding claims, characterized in that the distal region (130) of the bone anchoring element (10) has a cannulation (14) and fenestration openings (141) for bone cement augmentation, which are oriented cranially and caudally when the bone anchoring element (10) is placed in the vertebra (60).

13. The bone anchoring device according to any one of the preceding claims, characterized in that the pitch of the wings (150, 151) between the two wing orientations (440 and 441) is between 100 mm to 300 mm, in particular 150 mm to 250 mm, in particular 160 mm to 200 mm.

14. The bone anchoring device according to any one of the preceding claims, characterized in that, that the bone anchoring element (10) is configured in such a way that before the insertion of the bone anchoring element (10), the distal wing orientation (440) corresponds to the main orientation of the pedicle in the cranial- caudal direction (46), and, in the final position, the proximal wing orientation (441) now corresponds to the main pedicle orientation (46), and in that the distal wing orientation (440) is substantially perpendicular to the main pedicle orientation (46).

15. The bone anchoring device according to any one of the preceding claims, characterized in that the fork head has a pressure piece (91), wherein the pressure piece (91) partially surrounds the bone anchoring element (10) on the ball head (100), and the pressure piece (91) forms at the distal area at least one slot (912), in that the pressure piece (91) has a resilient area (911) such that the pressure piece (91) can enclose the ball head (100) in a resilient manner, and in that the pressure piece (91) proximally forms a seat for the connecting rod (913).

16. The bone anchoring device according to any one of the claims 3, 4 or 7, characterized in that the pedicle area (120) of the bone anchoring element (10, 11, 12) has a partial threaded bone section (18), in that this partial threaded bone section (18) is joined with or connected to a tool attachment point (182), and in that the threaded bone section (18) is rotatably but fixedly mounted with respect to the bone anchoring element (10, 11, 12).

17. The bone anchoring device according to any one of the preceding claims, characterized in that the bone anchoring element (10) has an indicator (185) which allows inferring the distal wing alignment (440) and / or proximal wing alignment (441).