Bone anchor device

Abstract

A bone anchor device is provided for bonding a rod to bone. [Solution] The bone anchor element (1) comprises a shank and a head (3) for fixing to a bone; a receiving component (5) having first and second ends, a channel for receiving a rod (100), a passage extending from the first end to the second end defining a central axis, a receiving space for accommodating the head of the bone anchor element, and at least one through hole (58) traversing the central axis; at least one restricting element (7) configured to be inserted into the through hole of the receiving component; and a monolithic pressure element that applies pressure to the head so that the head is rotatable relative to the receiving component and can be fixed at a certain angle relative to the receiving component, wherein when the restricting element is in the through hole, it interacts with the pressure element or the head to prevent rotational movement of the head within the receiving component or to restrict the rotational movement of the head to a single plane.

Description

Technical Field

[0001] The present invention relates to a bone anchor device comprising a bone anchor element and a receiving component for coupling a rod to the bone anchor element. In particular, the bone anchor device is a modular bone anchor device that can be selectively adapted to various clinical requirements.

Background Art

[0002] Bone anchor devices including a bone anchor element and a receiving component are used in orthopedic surgery, particularly spinal surgery, to couple a rod to a bone anchor element fixed to bone or vertebrae and to connect several bone anchor devices by that rod. In a multi-axis bone anchor device, since the head of the bone anchor element is rotatably received in the receiving component, the receiving component can take various angular positions in a plurality of planes with respect to the bone anchor element. Thus, the bone anchor element can be properly oriented with respect to the rod.

[0003] For example, a multi-axis bone anchor device is known from U.S. Patent No. 9,345,516. The multi-axis bone anchor device includes an anchor element having a shaft and a head, and a receiving component having a first end and a second end, a bore extending from the first end to the second end, a seat for receiving the head, and at least one threaded through-hole crossing the bore. The bone anchor device further includes a pressure element for applying pressure to the head such that the head is rotatable and can be fixed at an angle with respect to the receiving component. The pressure element has at least one hole at least partially aligned with the through-hole. At least one set screw is screwed into the through-hole and engages with the pressure element in the hole, so that a force is applied to the head by the pressure element and the head is maintained at an adjustable angular position with respect to the receiving component by friction.

[0004] Depending on the use and clinical application, it is desirable to provide a bone anchor device configured to restrict the rotation of the bone anchor element relative to the receiving component to a single plane, i.e., a monoplane bone anchor device, or a monoaxial bone anchor device in which the shank has a fixed angle, preferably zero angle, relative to the receiving component.

[0005] Various designs of single-plane bone anchor devices are known in which the shank of the bone anchor element can rotate on the receiving component only within a single plane. For example, U.S. Patent No. 7,749,258 describes a single-plane bone anchor device comprising a receiving component for receiving a rod, a pressure element, and a bone anchor element movable relative to the receiving component within a limited angular range about the longitudinal axis of the receiving component, where the angle is within a single plane. The movement of the bone anchor element relative to the receiving component is limited by a shape-fitting connection including a guide surface that cooperates between the head of the bone anchor element and the pressure element.

[0006] U.S. Patent Application Publication No. 2004 / 0204711 describes a bone screw having a head and a shank. The shank has a ball on it, and the head has a socket for receiving the ball. The bone screw includes two set screws that engage with the ball to secure the head in place relative to the shank.

[0007] A modular bone screw assembly, including a screw, housing, snap ring, saddle, set screw, and rod, is known from U.S. Patent Application Publication No. 2017 / 0049482. The bone screw assembly allows for multi-axis or uniplane movement of the screw relative to the housing. [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] There is still a need to provide a bone anchor device having a simple structure with only a few parts that can facilitate the implementation of at least multi-axis and / or uniplane and / or single-plane bone anchor devices. Therefore, the fundamental objective of the present invention is to provide a bone anchor device that can be used in a modular manner, enabling selectable functionality with respect to multi-axis, uniplane, or uniplane designs. [Means for solving the problem]

[0009] This objective is solved by the bone anchor device described in claim 1. Further developments are described in the dependent claims.

[0010] According to one embodiment of the present invention, a bone anchor device for connecting a rod to a bone is provided, the bone anchor device comprising an anchor element including a shank and a head for fixation to a bone, and a receiving component having a first end and a second end, the receiving component having a channel for receiving a rod, a passage extending from the first end to the second end and defining a central axis, a receiving space for accommodating the head of the bone anchor element, and at least one through hole traversing the central axis and including a female thread. The bone anchor device further comprises at least one restricting element including a male thread and a pressure element configured to be inserted into the through hole of the receiving component, the pressure element being positioned in the passage when the head and pressure element are in the receiving component such that the head is rotatable relative to the receiving component and can be fixed at a certain angle relative to the receiving component, and is configured to apply pressure to the head. When the restricting element is in the through hole, it is configured to interact with the pressure element or the head to prevent rotational movement of the head in the receiving component or to restrict the rotational movement of the head to a single plane.

[0011] "Lateral direction with respect to the through hole" means that the axis of the transverse hole intersects with the central axis, and preferably, the axis of the transverse hole is substantially perpendicular to the central axis.

[0012] The bone anchoring device allows for selective use as either a multi-axis or uniaxial bone anchoring device. A uniaxial bone anchoring device can be implemented by applying a limiting element to prevent any rotational movement of the bone anchor element head relative to the receiving component. This can be done at any time before surgery. Therefore, fewer components are needed, reducing the inventory required for surgery.

[0013] Furthermore, bone anchor devices originally designed as multiaxial bone anchor devices can be used for various uniaxial applications such as trauma applications, growth rod applications, posterior scoliosis correction, anterior scoliosis surgery, or anterior scoliosis tethering.

[0014] In further developmental forms, the limiting element includes a fractured portion, so that after forming the uniaxial bone anchor device, the fractured portion can be removed to reduce the external dimensions of the bone anchor device.

[0015] In a further embodiment, the receiving component of the bone anchor device is a first receiving component. A second receiving component can be connected to the first receiving component via a through-hole using a connecting element. This allows two rods to be connected parallel to a single bone anchor element.

[0016] In further embodiments, the head of the bone anchor element includes a recess that can be engaged by a limiting element to prevent any rotation of the bone anchor element relative to the receiving component, or to restrict the rotational movement of the head within the receiving component to a single plane. The recesses are separate from each other and preferably located on both sides of the head with respect to the shank axis. Thus, by selecting appropriate limiting elements, a uniaxial or uniplane bone anchor device can be provided. If the limiting elements are omitted, the bone anchor device functions as a multiaxial bone anchor device. Modular design greatly expands the range of applications.

[0017] According to a further embodiment, a bone anchor device for connecting a rod to a bone includes an anchor element including a shank and a head for fixing to the bone; a first receiving part having a first end and a second end, a channel for receiving a first rod, a passage extending from the first end to the second end defining a central axis, a receiving space for accommodating the head of the bone anchor element, and at least one through hole traversing the central axis; and a pressure element having a head that is rotatable relative to the receiving part and fixed at a certain angle relative to the receiving part. The device comprises: a pressure element positioned in a passage when the head and pressure element are in the receiving part and configured to apply pressure to the head; a second receiving part having a first end and a second end, a channel for receiving a second rod, a passage extending a distance from the first end to the second end defining a central axis, and at least one through hole traversing the central axis; and a connecting element inserted into the through hole of the second receiving part and the through hole of the first receiving part and configured to connect the second receiving part to the first receiving part.

[0018] In this embodiment, a bone anchor device originally designed as a multi-axis bone anchor device for a single rod can be easily transformed into a multi-axis bone anchor device having two receiving components for receiving two rods. Furthermore, by applying limiting elements, the bone anchor device can be transformed into a uniaxial or uniplane bone anchor device.

[0019] Since support components are more expensive and / or more difficult to manufacture compared to bone anchor elements, manufacturing costs and / or stock retention costs can be reduced if the same support component can be used for two or more clinical applications.

[0020] Further features and advantages will become apparent from the description of the embodiments and with reference to the attached drawings. In the drawings, [Brief explanation of the drawing]

[0021] [Figure 1]It is an exploded perspective view of a bone anchor device according to the first embodiment. [Figure 2] It is a perspective view of the bone anchor device of FIG. 1 in an assembled state. [Figure 3] It is a cross-sectional view of the bone anchor device shown in FIGS. 1 and 2, cut along a plane perpendicular to the rod axis of the inserted rod through the central axis. [Figure 4] It is a perspective view of the receiving part of the bone anchor device of FIGS. 1 to 3 as viewed from above. [Figure 5] It is a perspective view of the receiving part of FIG. 4 as viewed from the bottom. [Figure 6] It is a top view of the receiving part of FIGS. 4 and 5. [Figure 7] It is a cross-sectional view of the receiving part shown in FIGS. 4 to 6 in the cross-section along line A-A of FIG. 6. [Figure 8] It is a perspective view of the pressure element of the bone anchor device of FIGS. 1 to 3 as viewed from above. [Figure 9] It is a perspective view of the pressure element of FIG. 8 as viewed from the bottom. [Figure 10] It is a top view of the pressure element of FIGS. 8 and 9. [Figure 11] It is a cross-sectional view of the pressure element shown in FIGS. 8 to 10 in the cross-section along line B-B of FIG. 10. [Figure 12] It is a perspective view of the limiting element of the bone anchor device of FIGS. 1 to 3 as viewed from above. [Figure 13] It is a perspective view of the limiting element of FIG. 12 as viewed from the bottom. [Figure 14] It is a top view of the limiting element of FIGS. 12 and 13. [Figure 15] It is a cross-sectional view of the limiting element shown in FIGS. 12 to 14 in the cross-section along line D-D of FIG. 14. [Figure 16] It is a cross-sectional view of the bone anchor device of FIGS. 1 to 3 without a limiting element and with the head rotatable within the receiving part. [Figure 17] It is a cross-sectional view of the bone anchor device of FIG. 16 with an instrument inserted into the receiving part and the head to hold the bone anchor element at a zero angle position relative to the receiving part. [Figure 18]These are cross-sectional views of the bone anchor device shown in Figures 16 and 17, before the limiting elements are fully inserted. [Figure 19] Figures 17 and 18 show cross-sectional views of the bone anchor device with the limiting element in the end position. [Figure 20] Figure 19 is a cross-sectional view of a bone anchor device, where the limiting element is at its end position and the fractured portion of the limiting element is broken. [Figure 21] Figure 20 is a cross-sectional view of the bone anchor device with the instrument removed. [Figure 22] This is an exploded perspective view of a second embodiment of the bone anchor device. [Figure 23] Figure 22 is a cross-sectional view of the assembled bone anchor device, cut by a plane extending through the central axis and perpendicular to the longitudinal axis of the rod channel. [Figure 24] Figures 22 and 23 show a perspective view of the second receiving component of the bone anchor device, seen from the bottom. [Figure 25] Figure 24 is a perspective view of the second receiving component, seen from the bottom. [Figure 26] Figures 24 and 25 are top views of the second receiving component. [Figure 27] This is a cross-sectional view of the second receiving component shown in Figures 24-26, along the line FF in Figure 26. [Figure 28] Figures 22 and 23 are top-down perspective views of the connection elements of the bone anchor device. [Figure 29] Figure 28 is a perspective view of the connecting element from the bottom. [Figure 30] Figures 28 and 29 show cross-sectional views of the connecting elements, taken by a plane extending through the threaded axis of the connecting element. [Figure 31] This is a cross-sectional view of a third embodiment of the bone anchor device, taken by cutting through a plane extending through the central axis and perpendicular to the longitudinal channel of the rod channel. [Figure 32] This is a magnified view of a detail of Figure 31. [Figure 33] Figures 31 and 32 are perspective views of the bone anchor devices with limiting elements inserted. [Figure 34] Figure 33 is a perspective view of the bone anchor device, showing the fractured portion of the limiting element. [Figure 35] Figures 31-34 are top-down perspective views of the receiving components of the bone anchor device. [Figure 36] Figure 35 is a perspective view of the receiving component as seen from the bottom. [Figure 37] Figures 35 and 36 are cross-sectional views of the receiving component, taken by cutting through a plane that extends through the central axis and is perpendicular to the longitudinal axis of the rod channel. [Figure 38] Figures 31-34 are top-down perspective views of the pressure elements of the bone anchoring device. [Figure 39] Figure 38 is a perspective view of the pressure element from the bottom. [Figure 40] Figures 38 and 39 are top views of the pressure elements. [Figure 41] Figure 40 shows a cross-sectional view of the pressure element shown in Figures 38-40, along line GG. [Figure 42] Figures 31-34 or 46-49 are perspective views of some of the bone anchor elements of the bone anchoring device. [Figure 43] Figure 42 is a cross-sectional view of a bone anchor element. [Figure 44] Figures 31-34 are top-down perspective views of the limiting elements of the bone anchor device. [Figure 45] This is a side view of the limiting element in Figure 44. [Figure 46] This is a cross-sectional view of a fourth embodiment of the bone anchor device, taken by cutting through a plane extending through the central axis and perpendicular to the longitudinal axis of the rod channel. [Figure 47] This is a magnified view of a detail of Figure 46. [Figure 48] Figures 46 and 47 are perspective views of the bone anchor device with the limiting element inserted. [Figure 49] Figures 46 and 47 are perspective views of the bone anchor device, showing the fractured portion of the limiting element. [Figure 50]Figures 46-49 are top-down perspective views of the limiting elements of the bone anchor device. [Figure 51] This is a side view of the limiting element in Figure 50. [Modes for carrying out the invention]

[0022] Referring to Figures 1-21, a first embodiment of a bone anchor device is described. In particular, as shown in Figures 1-3, the bone anchor device includes a bone anchor element 1 having a shank 2 for fixation to a bone or vertebra, and a head 3. The shank 2 has a bone engagement function, such as a screw thread. The head 3 is formed as a segment of a sphere and therefore has a spherical outer surface portion. The spherical outer surface portion is preferably smooth, i.e., without screw threads or wavy lines. Furthermore, the head 3 has an engagement portion 4 at its free end for engaging with a tool such as a screwdriver. Furthermore, the bone anchor device includes a receiving component 5 for receiving a rod 100 configured to receive the head 3 of the bone anchor element 1 and connect several bone anchor devices. The receiving component 5 is provided with a pressure element 6 for applying pressure to the head 3 of the bone anchor element 1 and supporting the rod 100. A pair of limiting elements 7 are configured to cooperate with the pressure element 6 to apply a force to the head 3 inserted by the pressure element 6 such that the head 3 does not rotate relative to the receiving component 5. A locking element 8 in the form of an internal screw or set screw is provided to lock the head 3 and rod 100 within the receiving part 5.

[0023] The receiving component will be described in more detail, as shown in Figures 4 to 7. The receiving component 5 has a first end, i.e., an upper end 5a, and a second end, i.e., a lower end 5b, opposite the upper end 5a. Generally, the receiving component 5 may have a substantially cylindrical shape with a central longitudinal axis C extending through the upper end 5a and the lower end 5b. Coaxial with the central axis C, a passage 51 is provided, extending from the upper end 5a to the lower end 5b and forming an opening 52 at the lower end 5b. The passage 51 extends away from the upper end 5a into a housing space 53 configured to receive the head 3 and at least a portion of the internal pressure element 6. The housing space 53 narrows toward an opening 52 of a constricted portion 53a adjacent to the opening 52 at the lower end 5b, which may be, for example, tapered, and more specifically, a conical surface capable of cooperating with the corresponding surface of the pressure element 6. The width of the opening 52 may be greater than the maximum width of the head 3, and the head 3 may be inserted into the housing space 53 from the lower end 5b. In order to allow insertion of the head 3 from the lower end 5b, the width of the housing space 53 is such that the pressure element 6 expands inside, allowing insertion of the head 3.

[0024] The receiving part 5 further has a substantially U-shaped recess 54 that starts from the upper end 5a and extends toward the lower end 5b. The U-shaped recess 54 forms a free leg portion 55 and defines a channel that opens toward the first end 5a to receive the rod 100.

[0025] In exemplary embodiments, an internal thread 56 is formed on the inner surface of the leg portion 55, which is either a square thread or another flat thread. A first circumferential groove 57a may be provided on the inner wall of the leg portion 55 at a distance from the bottom 54a of the U-shaped recess 54. The first internal groove 57a may be provided with a stopper to restrict upward movement toward the first end 5a of the pressure element 6 when the pressure element 6 is assembled with the receiving component 5 or in the insertion position. Between the first circumferential groove 57a and the housing space 53, there may be a second circumferential groove 57b for engaging with a portion of the pressure element 6 to secure the pre-locked position of the pressure element 6.

[0026] The receiving component 5 further includes two threaded through-holes 58 extending from the outer surface of the receiving component 5 into the passage 51. The threaded through-holes 58 may be offset 180 degrees from each other and positioned at 90 degrees to the channel formed by the U-shaped recess 54. The axis a of the threaded through-holes 58 preferably extends substantially perpendicularly, more preferably perpendicular to the central axis C, and intersects the central axis C. The axial position of the axis a of the threaded through-holes 58, i.e., the distance from the lower end 5b, is such that when the pressure element 6 and the head 3 are inserted, the limiting element 7 extending through the threaded through-holes 58 can engage with the pressure element 6. More specifically, the position of the threaded through-holes 58 is such that force is applied to the inserted head 3 by the limiting element 7 via the pressure element 6, preventing the head 3 from rotating within the receiving component 5. In the embodiment, the axis a of the threaded through-holes 58 is located substantially axially on the upper surface of the inserted head 3.

[0027] Furthermore, preferably, lateral holes 59, smaller in diameter than the threaded through holes 58, may extend through each leg 55 at circumferential positions approximately at the center of each leg 55, which is axially above the threaded through holes 58 in a direction perpendicular to the central axis C and toward the upper end 5a. The through holes 59 may serve to accommodate pins 9, as shown in Figures 1-3. The pins 9 are configured to engage with the pressure element 6 to form a fixing device for fixing the pressure element 6 so as not to rotate. Furthermore, the pins 9 can restrict the upward movement of the pressure element 6.

[0028] A circumferential groove 500a may be provided on the outer surface of each leg 55, at a certain distance from the lower end 5b and above the bottom 54a of the U-shaped recess 54. A circumferential groove 500b may be provided at a corresponding position on the inner surface of the leg 55, and the leg 55 can be weakened at the location of the outer groove 500a. As a result, the upper part 55a of each leg 55 can be fractured down to the upper end 5a. Thus, the upper part 501 of each leg 55 functions as an extension tab that allows an instrument or fixing screw 8 to be guided downward at the intended location. This is particularly useful in minimally invasive surgery (MIS), in which only small incisions are made in the patient's skin.

[0029] The outer surface of the leg portion 55 may be provided with, for example, a longitudinal recess 502 and / or a mounting projection 503 for engaging with a tool or instrument. The mounting projection 53 may be positioned below the groove 500a, but toward the upper end portion 5a, and above the threaded through hole 58 and the transverse hole 59. More specifically, the mounting projection 503 may have a substantially triangular shape when viewed from above, with its tip portion 503a facing the upper end portion 5a. The circumferential width of the base portion 503b of the mounting projection 503 on the side opposite to the tip portion 503a may be the same as or greater than the width of the threaded through hole 58.

[0030] The pressure element 6 is described with further reference to Figures 8 to 11. Preferably, the pressure element 6 is a monolithic component located within the passage 51 and configured to surround the head 3 laterally and from the free end of the head in order to apply pressure to the head when the head 3 and the pressure element 6 are located within the receiving component 5, wherein the head is rotatable relative to the receiving component and can be locked at a certain angle relative to the receiving component.

[0031] More specifically, the pressure element 6 may be substantially cylindrical in shape, having a first end, i.e., an upper end 6a, and a second end, i.e., a lower end 6b, and having an outer diameter that allows the pressure element 6 to move within the passage 51 of the receiving component 5. A rod receiving recess 61 is formed in the rod support surface 61a at the upper end 6a. The rod support surface 61a may have a substantially V-shaped cross-section with a longitudinal axis L extending substantially perpendicular to the cylindrical axis of the pressure element 6, which coincides with the central axis C of the receiving component 5 when the pressure element 6 is inside the receiving component 5. The depth of the rod receiving recess 61 may be less than the diameter of the rod 100. Thus, when the rod 100 is placed on the rod support surface 61a, the rod protrudes beyond the upper end 6a of the pressure element, as shown, for example, in Figure 3. The V-shape of the rod support surface 61a makes it easier to use rods of different diameters.

[0032] Furthermore, the rod receiving recess 61 is formed such that grooves 63 create two free legs 62 on each side that can be separated from the rod support surface 61a. This gives the legs 62 slight flexibility in the direction transverse to the longitudinal axis of the rod support surface 61. The free ends of the legs 62 may have radially projecting rims 62a, the upper surface of which forms the upper end 6a of the pressure element 6. The rims 62a are configured to engage with grooves 57a and 57b provided on the inner surface of the legs 55 of the receiving component 5 to fix the insertion position or pre-locked position of the pressure element 6 within the receiving component 5.

[0033] Adjacent to the lower end 6b of the pressure element 6, the outer surface portion 64 may be tapered, preferably conical, and the outer surface portion 64 is configured to cooperate with the constricted portion 53a of the receiving component 5. Furthermore, the pressure element 6 has a hollow head receiving portion 65 having an opening at the lower end 6b for inserting the head 3. The head receiving portion 65 may have a substantially spherical lower section 65a and upper section 65b that are molded to interlock with the spherical head 3. The intermediate section 65c has a larger inner diameter to facilitate the insertion of the head 3. Furthermore, a plurality of recesses 66 are formed that extend through the entire pressure element 6 into the enlarged section 65c and open to the second end through a substantially axially extending slit 66a. The recesses 66 may have an inverted teardrop shape, with the wider portion located closer to the lower end 6b. The recesses 66 and slit 66a are configured to expand when the head 3 is inserted. Generally, the number, shape, and dimensions of the recesses 66 are selected to obtain the desired flexibility, which allows the head 3 to be inserted through the lower end until it is received by the head receiving portion 65. The dimensions of the head receiving portion 65 may also be such that the head 3 can be held in it by friction before it is finally fixed in place.

[0034] Each of the leg portions 62 has an elongated through-hole 67 extending axially at its circumferential center, which serves to receive the pin 9 and the limiting element 7, as shown in Figures 1-3. To receive a portion of the limiting element 7, the bottom of the elongated through-hole 67 has a broad, substantially conical portion that forms a first cooperating surface 67a, configured to cooperate with a second cooperating surface of the limiting element 7, as will be described in more detail below. The first cooperating surface 67a extends laterally with respect to the central axis C at an axial position slightly above the upper spherical portion 65b of the head receiving portion 65 below the groove 63, as can be seen particularly in Figure 11. This allows the limiting element 7 to directly apply force to the top of the inserted head 3 via the cooperating surfaces of the pressure element 6 and the limiting element 7. Finally, a coaxial bore 69 is formed in the pressure element 6 to allow access to the engagement recess 4 of the head 3 by a driver.

[0035] Referring here to Figures 12-15, the limiting element 7 is described. The limiting element 7 comprises a threaded portion 70 configured to cooperate with the threaded through-hole 58 of the receiving component 5. The front portion 71 is formed as a cone that protrudes from the threaded portion 70 and may have a flat end. The outer diameter of the base of the front portion 71 adjacent to the threaded portion 70 is smaller than the outer diameter of the threaded portion 70. More specifically, the front portion 71 is shaped to fit into the lower conical portion of the elongated hole 67 of the pressure element 6. Thus, the outer surface of the conical front portion 71 forms a second cooperating surface configured to cooperate with the first cooperating surface 67a of the pressure element 6. The rear portion 72, on the other side of the threaded portion 70 and opposite to the front portion 71, forms the head of the limiting element 7. The rear portion 72 is substantially cylindrical and has a larger outer diameter than the threaded portion 70. The free end face of the rear portion is provided with an engagement recess 73 for engaging with a tool such as a screwdriver. The engaging recess 73 may have a Torx® shape, as shown in Figures 12 and 14. The overall dimensions of the rear portion 72 are such that it can be easily gripped so that the limiting element 7 can be screwed into the threaded hole 58 of the receiving part 5. Between the threaded portion 70 and the rear portion 72, there is a predetermined fracture region 74, or weakened section, which has an outer diameter slightly smaller than that of the threaded portion 70. When a torque exceeding a predetermined torque is applied to the rear portion 72, the rear portion 72 is configured to detach from the predetermined fracture region 74.

[0036] The components and parts of the bone anchor device may be made of any material, preferably titanium or stainless steel, or any biocompatible metal or metal alloy or plastic material. As a biocompatible alloy, NiTi alloy, such as Nitinol, may be used. Other usable materials include, for example, magnesium or magnesium alloys. Biocompatible plastic materials that may be used include, for example, polyether ether ketone (PEEK) or poly-L-lactide acid (PLLA). The components can be made from the same or different materials.

[0037] When in use, the bone anchor device can be applied as either a multi-axis bone anchor device or a uniaxial bone anchor device.

[0038] As shown in Figure 16, the pressure element 6 is pre-assembled with the receiving component 5 such that the upper rim 62a of the pressure element 6 extends into the second groove 57b and the rod support surface 61a aligns with the channel formed by the U-shaped recess 54. The pin 9 extends through the through hole 59 into the elongated recess 67. This fixes the pressure element 6 in place so that it does not rotate. The head 3 of the bone anchor element 1 is inserted into the head receiving portion 65 of the pressure element from its lower end 5b. With the outer rim 62a held in the second groove 57b, the pressure element 6 is in a pre-locked position where the narrow outer portion 64 of the lower end of the pressure element 6 engages with the narrow inner portion 53a of the receiving component 5, and therefore the head 3 cannot be removed through the lower opening 52. In this position, as shown in Figure 16, the head 3 is still rotatable within the receiving component 5. When the bone anchor device is used as a multi-axis bone anchor device, the rod 100 is inserted into the U-shaped recess until it rests on the rod support surface 61a of the pressure element 6. To lock the bone anchor device, i.e., the head 3 and the rod 100, into the receiving part 5, the locking element 8 is screwed between the legs 55 until it presses against the rod, and so the pressure element moves further downward until the head 3 is locked in a specific angular position relative to the receiving part 5.

[0039] The limiting element 7 is used when the bone anchor device is used as a uniaxial bone anchor device, that is, when the axis of the shank 2 is permanently coaxial with the central axis C of the receiving component 5. First, as shown in Figure 17, the instrument 1000, which has an elongated bar with an anterior portion 1001, is inserted into the receiving component 5 from the upper end 5a until the anterior portion 1001 engages with the tool engagement recess 4 of the head 3. This causes the bone anchor element 1 to take a zero-angle position relative to the receiving component 5, i.e., the shank axis of the shank 2 is coaxial with the central axis C.

[0040] Next, the restricting element 7 is screwed into the threaded hole 58 as shown in Figure 18 until the conical front portion 71 having a second cooperative surface engages with the first cooperative surface 67a at the bottom of the elongated hole 67 of the pressure element 6, as shown in Figure 19. This applies increasing pressure to the head 3 via the pressure element 6 until the bone anchor element 1 is locked in the zero-angle position. The position of the longitudinal axis a of the threaded through hole 58 is selected so that the force generated by the restricting element 7 completely or nearly completely locks the head 3 in the receiving component 5. In addition, the bone anchor element 1 is prevented from rotating when the restricting element 7 is fully tightened.

[0041] When the reaction force exerted by the first cooperating surface 67a on the second cooperating surface 71 of the limiting element 7 exceeds a predetermined value, the rear portion 72 is separated from the threaded portion 70 at a predetermined fracture region 74, as shown in Figure 20. Since the head 3 of the bone anchor element 1 is locked in the zero-angle position, the device 1000 can then be removed, as shown in Figure 21. Thus, Figure 21 shows a uniaxial bone anchor device that can be used in the same way as any other uniaxial bone anchor device. The uniaxial bone anchor device can be inserted into a bone portion or vertebra by engaging the tool recess 4 of the head with a driver extending through the bore 69 of the pressure element.

[0042] Note that after the bone anchor device is finally locked with the locking element 8, the fractured portion 55a of the leg 55 can be separated.

[0043] Referring to Figures 22-30, a second embodiment of the bone anchor device is described. Parts identical or similar to those of the first embodiment are given the same reference numerals and their description is omitted. As shown in Figures 22 and 23, the bone anchor device according to the second embodiment includes the bone anchor device according to the first embodiment, i.e., a receiving component 5 having a pressure element 6 and a bone anchor element 1. In the second embodiment, the receiving component 5 forms a first receiving component. Furthermore, the bone anchor device includes a second receiving component 150 and a connecting element 170. The connecting element 170 is configured to connect the second receiving component 150 to the first receiving component 5 using one of the threaded through holes 58 of the first receiving component 5. This makes it possible to connect two rods to a single bone anchor element 1. Such applications can be used, for example, in growth rod applications where one rod is fixed and the other rod is slidable. This may be particularly useful in the treatment of scoliosis.

[0044] The second receiving part 150 differs from the first receiving part 5 in various ways, but mainly in that its lower part lacks a head receiving portion and instead has features for connecting the second receiving part 150 to the first receiving part 5. The second receiving part 150 is substantially cylindrical and has a passage 151 that terminates at a certain distance from the lower end 5b. The lower end 5b has a substantially flat surface. A transverse bore 152 is formed above the lower end 5b and in an axial position below the triangular mounting projection 503. The inner diameter of the transverse bore is larger than the outer diameter of the rear portion 172 of the connecting element 170 (see Figure 23), so that the connecting element 170 can be introduced and guided into the transverse bore 152. The transverse bore 152 opens on the side where the triangular projection 503 is located. A portion of the support component 150 around the lateral bore 152 is cut off so that its outer surface is rounded from the lower end 5b toward the triangular projection 503. On the opposite side, the lateral bore 152 has a section 153 having a smaller diameter, so that a shoulder 152a is formed between the lateral bore 152 and the section 153. The shoulder 152a forms a contact portion for a portion of the connecting element 170. The rod support recess 154 extends from the upper end to a certain distance from the lower end. The rod support recess 154 has a V-shaped bottom region 154a capable of supporting rods of different diameters. The recess 154 forms two free legs 155, including the upper part 154a above the outer groove 500a and the inner groove 500b, as in the first embodiment. The upper part 155a may be detached. On the leg portion 155 opposite to the leg portion 155 having the triangular projection 503, a triangular recess 504 is formed, having a shape corresponding to the shape of the triangular projection 503 and located in a position complementary to the position of the triangular projection 503 of the first receiving component 5. The triangular projection 503 of the first receiving component 5 can be received by the triangular recess 504 of the second receiving component 150. Furthermore, a shallow groove 505 is formed on the outer surface of the leg portion 155 having the triangular recess 504, extending parallel to the central axis C from the upper end 5a to approximately the lower end 5b. The shallow groove 505 is formed in a substantially cylindrical shape so as to fit into the outer surface of the leg portion 55 of the first receiving component 5.

[0045] Referring particularly to Figures 28 to 30, the connecting element 170 has a threaded portion 171 configured to be screwed into a threaded through hole 58 of the first receiving component 5. The front end of the connecting element 170 in the threaded portion may have a flat end face 171a. The rear portion 172 may have a shape similar to the limiting element 7 of the first embodiment, i.e., the rear portion 172 may have a cylindrical shape with an outer diameter larger than the outer diameter of the threaded portion 171 and a tool engagement recess 173. A predetermined fracture region 174 is formed adjacent to the rear portion 172, and a ring-shaped contact portion 175 is provided between the predetermined fracture region 174 and the threaded portion 171. The contact portion 175 has a flat contact surface 175a facing the front end 171a and configured to contact the shoulder portion 152a of the second receiving component 150. The outer edge of the contact portion 175 facing the rear portion 172 may be rounded.

[0046] During use, the second receiving part 150 can be attached to the first receiving part 5, as is most commonly seen in Figures 22 and 23, so that the bone anchor device is a bone anchor device for two rods. First, the first receiving part 5 and the second receiving part 150 are aligned so that the channels of the two rods are parallel. Next, the projection 503 of the first receiving part 5 is inserted into the complementary groove 504 of the second receiving part 150. Subsequently, the connecting element 170 is inserted into the lateral bore 152 until the threaded portion 171 extends through the section 153 of the lateral bore 152 into the threaded through hole 58 of the first receiving part 5. Next, the connecting element 170 is tightened until the contact surface 175a contacts the shoulder portion 152a. If a predetermined torque is exceeded, the rear portion 172 of the connecting element 170 breaks at a predetermined break region and becomes removable. This permanently connects the first receiving component 5 and the second receiving component 150. Finally, the bone anchor element 1 can be inserted into the bone or vertebra, and the rod 100 can be inserted into the first receiving component 5 and the second receiving component 150. Depending on the clinical application, both rods may be fixed with the locking member 8, or only one of the rods may be fixed with the locking member 8, while the other rod remains slidable within its respective receiving component. It should be noted that the first receiving component 5 and the second receiving component 150 can each accommodate rods of different diameters due to the V-shape of the rod support surface 61a of the pressure element 6 and the bottom 154a of the rod receiving recess 154.

[0047] In the embodiment shown in Figure 23, the bone anchor device is still multi-axis, i.e., the head 3 is rotatable within the first receiving component 5. However, a single-axis bone anchor device may be provided by using a limiting element 7, as shown in the first embodiment, which is inserted into the lateral through-hole 58 opposite to the lateral through-hole 58 into which the connecting element 170 is inserted.

[0048] Referring here to Figures 31-51, third and fourth embodiments of the bone anchoring device are described. The components form a modular system and can be combined in various ways to provide a multi-axis bone anchoring device, a uniaxial bone anchoring device, or a single-plane bone anchoring device.

[0049] First, the uniaxial bone anchor device will be described with reference to Figures 31-45. The uniaxial bone anchor device differs from the first embodiment shown in Figures 1-30 in the design of the receiving component, the head of the bone anchor element, and the limiting element. Referring specifically to Figures 31-37, the receiving component 5' differs from the receiving component 5 in the position and shape of the threaded through-hole 58' that opens below the housing space 53. All other parts are identical or highly similar to the receiving component 5 of the first embodiment and will therefore not be described. The lateral threaded through-hole 58' is positioned axially away from the lower end 5b of the receiving component 5', corresponding to the position where the inserted head 3' has its maximum outer diameter. As can be seen from Figures 31 and 32, the inserted limiting element 7' engages with the head 3' of the bone anchor element 1 substantially in the region where the head 3' has its maximum outer diameter. Furthermore, a countersunk hole 508 is formed on the outer surface around the threaded through-hole 58', providing a contact surface 508a for the limiting element of the fourth embodiment.

[0050] As shown in Figures 38-41, the pressure element 6' differs from the pressure element 6 of the first embodiment in that it lacks the wide lower part of the elongated hole 67. Instead, the pressure element 6' has two through holes 600 positioned below the elongated hole 67, offset 180 degrees from each other in the circumferential direction. The through holes 600 are not threaded and function to allow a portion of the limiting element 7' to pass through. When the pressure element 6' is in the receiving component 5' and the upper ring 62a is in the pre-locked position within the lower groove 57b, the through holes 600 align with the threaded through holes 58' of the receiving component 5'.

[0051] Referring here to Figures 42 and 43, the bone anchor element 1' is described. The bone anchor element 1' differs from the bone anchor element 1 of the first embodiment in the design of its head. The head 3' of the bone anchor element 1' has two circumferential recesses 31 offset by 180 degrees from each other at axial positions corresponding to the maximum diameter of the head 3'. The recesses 31 are conical in shape, corresponding to the anterior portion of the limiting element 7', and have a substantially flat bottom surface that forms a first cooperating surface 31a for cooperating with a second cooperating surface provided on the limiting element 7'. The dimensions of the conical shape of the recesses 31 are such that, when the bone anchor device is assembled, the anterior portion of the limiting element 7' can be received therein with some play in a direction parallel to the central axis C.

[0052] Optionally, bone anchor element 1' and bone anchor element 1 may have a coaxial channel 32 for introducing a substance such as bone cement into the bone.

[0053] Referring to Figures 44 and 45, the limiting element 7' is described. The limiting element 7' differs from the limiting element 7 of the first embodiment mainly in the design of its front portion. The limiting element 7' comprises a threaded portion 70, similar to the first embodiment, and an elongated front portion 71' which may have a cylindrical portion 71a' adjacent to the threaded portion 70, having an outer diameter smaller than the outer diameter of the threaded portion 70 and slightly smaller than the diameter of the hole 600 of the pressure element 6'. Adjacent to the cylindrical portion 71a' is a conical portion 71b' that narrows toward a flat end face 71c' configured to cooperate with the bottom 31a of the recess 31 of the head 3'. Thus, the flat end face 71c' forms a second cooperating surface. The rear portion 72 may be the same as the rear portion of the limiting element 7 of the first embodiment. A predetermined fracture region 74' between the rear portion 72 and the threaded portion 70 may widen conically between the threaded portion 70 and the rear portion 72. However, any other shape for a given fracture region may be considered.

[0054] When the receiving component 5', which has a pre-assembled pressure element 6' and anchor element 1', is used without the limiting element 7', the bone anchor device functions as a multi-axis bone anchor device. If the clinical application requires a uniaxial bone anchor device, the limiting element 7' is screwed into the threaded transverse hole 58' until its flat end face 71c' presses against the flat bottom surface 31a of the recess in the head 3' of the bone anchor element 1'. This gives the shank 2 a fixed orientation relative to the receiving component 5' so that a uniaxial bone anchor device is formed. Because the front portion 71' has axial play in the hole 600 of the pressure element, the locking force of the fixing element 8 is transmitted to the head 3 via the pressure element 6' when the bone anchor device is finally locked using the locking element 8.

[0055] When the torque applied to the rear portion 72 exceeds a predetermined torque, the rear portion 72 is separated at a predetermined fracture region 74', as shown in Figure 34.

[0056] Referring to Figures 46-51, a fourth embodiment of the bone anchor device is described. The bone anchor device of the fourth embodiment is identical to the bone anchor device of the third embodiment, except for the design of the limiting element. Thus, the receiving component 5', pressure element 6', and bone anchor element 1' are identical. The limiting element 7'' shown in Figures 50 and 51 differs from the limiting element 7' shown in Figures 44 and 45 only in that it further includes an annular projection 75'' formed adjacent to the threaded portion 70 in the direction of the rear portion 72. The annular projection 75'' has an outer diameter larger than the outer diameter of the threaded portion 70 and smaller than the outer diameter of the rear portion 72. On the side facing the free end face 71c', the annular projection 75'' has a flat contact surface 75a'' configured to cooperate with the flat contact surface 508a at the bottom of the countersunk hole 508 around the threaded through hole 58' of the receiving component 5' shown in Figures 35-37. Thus, the flat contact surface 75a'' forms a second cooperating surface. Since the flat contact surface 75a'' is axially positioned relative to the flat end surface 71c'', the conical front portion 71b'' does not press against the bottom 31a of the conical recess 31 of the head 3'' when the first cooperating surface 508a and the second cooperating surface 75a'' are pressed against each other as shown in Figures 46 and 47. As a result, the bone anchor element 1'' is rotatable around a pivot axis provided by the threaded axis of the limiting element 7''. Consequently, the rotation of the bone anchor element 1'' is restricted to a single plane. In the embodiments shown in Figures 46-49, the single plane is defined by a plane that spans the longitudinal axis of the channel of the rod and the central axis C of the receiving component 5''.

[0057] When a predetermined torque is exceeded, the rear portion 72 is detached, forming a single-plane bone anchor device as shown in Figure 49, which can be inserted into the bone. In this embodiment, axial play allows the pressure element 6' to move slightly downward when the bone anchor device is finally locked by tightening the locking element 8. Depending on the precise position of the contact surface 75a" or the length of the front portion 71', a limiting element 7" may be provided, configured to preload the head 3' when the front surface 71c' is in slight contact with the bottom 31a of the recess 31, and it should be noted that a specific angular position in a single plane can be temporarily maintained by friction. This position may be changed by overcoming the frictional force.

[0058] Furthermore, it should be noted that the holes 600 of the pressure element 6' can be positioned in other locations, for example, by aligning the holes with the channels of the rod so that the pivot surface of the bone anchor element 1' is perpendicular to the longitudinal axis of the channels of the rod. To provide more than one pivot surface, it is also conceivable to have more than two opposing holes 600. For example, four holes could be provided, two of which are circumferentially located at the leg positions of the pressure element 6' and two additional holes aligned with the channels of the rod. The receiving component 5' may have threaded through holes 58' at corresponding positions. The head 3' may also have more than two recesses 31.

[0059] In a further modification, the head 3 may have one or more indicator features (not shown) on its free end face that indicate the circumferential position of the recess 31. This facilitates alignment between the recess 31 and the threaded hole 58' of the receiving part 5' when the head 3' is inside the receiving part 5'.

[0060] The bone anchor devices according to the third and fourth embodiments provide a modular system that allows for the assembly of various bone anchor devices from a small number of parts.

[0061] Modifications of the above embodiments are possible. In particular, the shape of the parts is not limited to the detailed shape shown in the figures. Deviations are possible and may be included in this disclosure. In the embodiments, two threaded through holes are shown, but one threaded through hole and one limiting element may suffice.

[0062] Instead of the locking member 8 being a set screw, all other types of locking assemblies known in the art may be used. For the bone anchoring element, all types of bone anchoring elements suitable for fixation to bone or vertebrae may be used, such as bone screws and bone nails. As used herein and in the appended claims, the term “rod” shall be understood to include any elongated member, regardless of the cross-sectional shape of the elongated member. Specifically, the spinal stabilization rods used herein may have substantially circular, elliptical, or angled cross-sections. Such cross-sections may further vary along the length of the rod. The rod may be rigid or flexible.

[0063] Furthermore, the receiving component and the housing space for the pressure element may be designed to allow the bone anchor element to rotate to a larger angle of rotation relative to one side compared to the other sides.

Claims

1. A bone anchor device for connecting a rod to bone, A bone anchor element (1, 1') having a shank (2) and a head (3, 3') for fixation to bone, A receiving component (5, 5') having a first end (5a) and a second end (5b), a channel (54) for receiving a rod (100), a passage (51) extending from the first end to the second end, defining a central axis (C), a receiving space (53) for accommodating the head (3, 3') of the bone anchor element (1, 1'), and at least one through hole (58, 58') traversing the central axis (C), the lateral through hole (58, 58') including a female thread, A limiting element (7, 7', 7") including a male screw, is configured to be inserted into the through hole (58, 58') of the receiving component (5, 5'), A pressure element (6, 6') is provided, wherein the head (3, 3') is rotatable relative to the receiving component (5, 5') and is positioned within the passage (51) when the head (3, 3') and the pressure element (6, 6') are in the receiving component (5, 5') such that the head (3, 3') is rotatable relative to the receiving component (5, 5') and can be fixed at a certain angle relative to the receiving component (5, 5'), and is configured to apply pressure to the head (3, 3'), A bone anchor device, wherein the limiting element (7, 7', 7") is configured to interact with the pressure element (6, 6') or the head (3, 3') when it is located within the through hole (58, 58') to prevent rotational movement of the head (3, 3') within the receiving component (5, 5') or to restrict the rotational movement of the head (3, 3') to a single plane.

2. The bone anchor device according to claim 1, wherein the pressure element (6, 6') is configured to surround the head (3, 3') laterally and from the free end of the head (3, 3'), and preferably the pressure element is a monolithic component.

3. The bone anchor device according to claim 1 or 2, wherein the longitudinal axis (a) of the through holes (58, 58') extends perpendicular to the central axis (C).

4. The bone anchor device according to any one of claims 1 to 3, wherein the limiting element (7, 7', 7") comprises a portion (72) configured to break in a fracture region (74, 74', 74') when the limiting element (7, 7', 7") engages with the pressure element (6, 6') or the head (3, 3') to prevent or restrict the rotational movement of the head.

5. The bone anchor device according to any one of claims 1 to 4, wherein two transverse through holes (58, 58') are preferably located circumferentially perpendicular to the longitudinal axis of the channel for the rod, on the opposite side from the central axis (C).

6. The bone anchor device according to any one of claims 1 to 5, wherein the pressure element (6) has a first cooperating surface (67a) that cooperates with the second cooperating surface (71) of the limiting element (7) so that a force is applied to the head (3) that locks the head in the receiving part (5) so that the head (3) does not rotate.

7. The bone anchor device according to claim 6, wherein the first cooperating surface (67a) and the second cooperating surface (71) are inclined with respect to the central axis (C).

8. The bone anchor device according to any one of claims 1 to 7, wherein the receiving component is a first receiving component (5) configured to receive a first rod, and the bone anchor device further comprises a second receiving component (150) for receiving a second rod, and the second receiving component (150) is connected to the first receiving component (5) by a connecting element (170) that engages with the second receiving component (150) and the lateral through hole (58) of the first receiving component (5).

9. The bone anchor device according to claim 8, wherein the second receiving component (150) has a through hole (153) through which the connecting element (170) extends into the lateral through hole (58) of the first receiving component (5), and preferably the connecting element (170) has a contact surface (175a) that abuts against the shoulder portion (152a) at the outer edge of the through hole (153) of the second receiving component (150).

10. The bone anchor device according to claim 8 or 9, wherein the channel (154) in the second receiving component (150) for receiving the second rod is parallel to the channel (54) in the first receiving component (5) for receiving the first rod.

11. The bone anchor device according to any one of claims 1 to 10, wherein the head (3') comprises at least one recess (31), preferably two opposing recesses, extending across the shank axis for engagement with the limiting element (7', 7"), the bone anchor device according to any one of claims 1 to 10.

12. The bone anchor device according to claim 11, wherein the recess (31) is substantially, preferably precisely, positioned axially at the location where the head (3') has its maximum outer diameter.

13. The bone anchor device according to claim 11 or 12, wherein the limiting element (7') cooperates with the head (3') to prevent rotational movement of the head.

14. The bone anchor device according to any one of claims 11 to 13, wherein the head (3') comprises a first cooperating surface (31a), the limiting element (7') comprises a second cooperating surface (71c'), the first cooperating surface and the second cooperating surface extend substantially parallel to the central axis (C), preferably the first cooperating surface (31a) is the bottom of the recess (31) of the head (3'), and the second cooperating surface (71c') is the end face of the limiting element (7').

15. The bone anchor device according to claim 11 or 12, wherein the limiting element (7") cooperates with the head (3') so that the head (3') can rotate in a single plane, preferably having a first cooperating surface (508a) formed on the edge of the transverse hole of the receiving component (5) and a second cooperating surface (75") formed on the limiting element (7"), so that the front portion (71') of the limiting element (7") is received in the recess (31) of the head (3') with play that allows the head (3') to rotate in a single plane.

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