System with anterior cervical plate and uniform screw locking concept

Abstract

The invention relates to a system comprising an anterior cervical plate with receiving openings for bone screws and a locking mechanism for inserted bone screws that are screwed to a vertebral body and press the cervical plate against the vertebral body, wherein the locking mechanism has a plate-type locking body (16) which is movably held on the cervical plate and which can be moved from a position that leaves a receiving opening as freely accessible as possible into a locking position in which the screw head lying in the receiving opening is covered by the locking body and thus the migration of the screw out of the cervical plate is prevented. In order to design the system in such a way that it is easy to operate while maintaining a high degree of security against a loosening of the bone screws and it offers maximum flexibility in the design of the cervical plate for a wide range of treatment options, the locking body is formed uniformly for cervical plates for hybrid and dynamic treatment options, by a thin disc (16) which is fixed to the anterior cervical plate so as to be rotatable about an axis of rotation substantially perpendicular to the cervical plate (10), and which has, angularly distributed over the circumference, at least one locking arm (18) and a support portion (20), which is a component of a catch mechanism.

Description

[0001] System with anterior cervical plate and uniform screw locking concept

[0002] Description

[0003] Technical field

[0004] The present disclosure relates to a system with an anterior cervical plate and at least one locking element for a bone screw inserted therein. Such systems are used for mono- and multi-segmental stabilization of the cervical spine. More precisely, the disclosure relates to a system with an anterior cervical plate and a uniform locking concept for bone screws inserted therein.

[0005] Several cervical plate systems are available on the market, differing, among other things, in their locking mechanisms for the bone screws used. Such plate systems are already marketed by the applicant under the name Quintex and, for example, by companies such as Bricon (under the name Shark CP Pro), Zimmer (Trinica), Medtronic (Zevo), Stryker (Ozark), Biomet (Maxan), DePuy Synthes (Skyline), GlobusMedical (Assure), Nuvasive (C360), and Biomed (Quantum).

[0006] The cervical plate system according to US 8,906,077 B2 or EP 2 217 163 B1 uses a locking element in conjunction with a separate fixing element.

[0007] In the system according to US 7909,859 B2, the screws are secured against loosening by means of clamps. AE2096P-WQ-0001

[0008] 2 / 27

[0009] The system according to US 8,500,737 B2 uses either a snap ring that slides in a longitudinal guide or a sliding plate to secure the inserted bone screw.

[0010] The cervical plate known from document US 10,492,836 B2 is equipped with a locking mechanism in the form of a wing nut, which is secured to the cervical plate by means of a clamping nut inserted from the rear of the cervical plate. A similar locking element is used in the system according to US 8,480,717 B2.

[0011] A screw locking system according to DE 202 21 560 U1 uses a washer with an elongated hole that can be moved on the underside of the screw head in question.

[0012] The locking system according to US 8,778,001 B2 provides locking plates that are held in place by spring-loaded spreader legs in an undercut groove of the cervical plate.

[0013] The plate system according to US 8,747,441 B2 uses spring-loaded C-rings or slotted rings as locking elements, which are received in a corresponding groove in the cervical plate.

[0014] The locking mechanism according to US 8,702,766 B2 uses a plate body per screw that can be rotated about an axis and has a radially and circumferentially projecting spring arm, at the distal end of which a claw body is located. When the plate body is rotated, the spring arm bends and is forced into an undercut guide groove in the plate perpendicular to the plane of the plate body. Upon reaching the locking position, the claw body snaps into a recess in the plate. To ensure sufficient axial compliance of the spring arm, plate material must be removed on both axial sides of the spring arm. This design therefore requires a greater plate thickness. AE2096P-WG-0001

[0015] 3 / 27

[0016] The cervical plate system according to US11,166,755 B2 secures two adjacent bone screws by means of spring rings that snap over the respective screw head and can be expanded with an adjusting screw located laterally between adjacent screw holes.

[0017] In the generic cervical plate system known from document EP 1 737 365 B1, the locking element for the screws is formed by a spring plate which is received in a longitudinal guide.

[0018] The application is based on the task of creating a generic system with an anterior cervical plate and locking mechanism for inserted bone screws that is easy to use and offers flexibility in the design of the cervical plate for a wide range of treatment options.

[0019] This problem is solved by the system according to claim 1.

[0020] According to the innovation, the locking element for cervical plates used in hybrid and dynamic prosthetic options is formed by a thin disc rotatably fixed to the anterior cervical plate about an axis of rotation that is substantially perpendicular to the cervical plate. This disc has at least one locking arm angularly distributed around its circumference and a support section, preferably lying in the plane of the disc, which forms part of a latching mechanism. This locking mechanism is extremely space-saving, as the thin disc can be manufactured with a thickness in the range of a fraction of a millimeter. Furthermore, the thickness of the plate, particularly when the support section lies in the plane of the disc, remains unaffected by this design of the locking element.On the other hand, the locking position of multiple locking arms can be synchronously achieved by simply rotating the disc, thus ensuring user-friendly operation. This enables sequential locking per level, with the particular advantage that the locking status of the disc is visually and tactilely perceptible to the operator. It has been shown that, by appropriately dimensioning the length of the respective locking arm, mounting holes in the form of AE2096P-WG-0001 can also be accommodated.

[0021] 4 / 27

[0022] The elongated holes with limited rotation angles of the disc can be covered at least to the extent necessary to reliably prevent screw migration out of the cervical plate. This locking mechanism is therefore uniformly applicable to cervical plates designed for both hybrid and dynamic fixation options. The innovative locking mechanism thus allows the anterior cervical plate to be equipped with receiving openings for the bone screws in the form of drilled holes and elongated slots, making the cervical plate system suitable for all common treatment options.

[0023] More precisely, the system is equally well-suited for both hybrid plates for so-called "constrained" restorations and dynamic plates for dynamic restorations. The term "constrained" refers to limited stability / stiffness of the connection between the plate and screw; "dynamic" refers to mobility (rotational and / or translational) between the screw and plate. Thanks to the locking mechanism, the locking status is easily identifiable not only visually, through the position of at least one locking arm, but also haptically, through the click, which further enhances user safety. Finally, the innovative, standardized locking concept makes it easy to identify where a locking arm might collide with a screw head, allowing for adjustment of the affected bone screw without the need for complicated maneuvers.

[0024] Advantageously, the locking element, in its design as a rotatably mounted disc in the cervical plate, has a support section that snaps into a detent position by rotating the disc through a predetermined angle. This detent can then be released by rotating the disc in the opposite direction. Opening the locking arms is simple, requiring only a rotation opposite to that used for closing, to facilitate easy maintenance.

[0025] The unique feature of the new system is that an anterior cervical plate with rotatable locking elements is equipped with an integrated detent mechanism for the bone screws. This arrangement ensures that locking or driving the thin disc does not impair the function of the cervical plate system.

[0026] Particular advantages arise when the support section interacts with a locking pin mounted on the cervical plate. As the disc is rotated, this pin deforms the support section before it reaches the locking position. This deformation can be purely elastic or elastic / plastic. Repeated opening and closing is thus possible without a significant or noticeable decrease in the locking torque. Furthermore, the thin plate forming the locking mechanism offers the additional advantage of not significantly increasing the overall thickness of the cervical plate system while minimizing the weakening of the cervical plate. This helps to better prevent irritation in the cervical spine region.

[0027] The resistance of the locking mechanism can be controlled particularly well when the support section is formed by a disc ring cutout or segment that is essentially arc-shaped. This segment is deformable radially when the disc is rotated by the locking pin, forming a detent for the locking pin. The deflection or deformation of the locking mechanism thus occurs in the radial direction. In this way, the spring component can be made relatively long while requiring little space. This is particularly useful for compensating for tolerances in the plate and the locking arm without negatively impacting the locking torque.

[0028] The innovative cervical plate system can be used with particular flexibility when the receiving holes for the bone screws consist of a spherical surface combined with a conical surface in the area of ​​their support surfaces. It is especially advantageous if the receiving holes are designed to accommodate and support both so-called "constrained" screws with a conical screw head and so-called variable screws with a spherical screw head. If the locking element is positioned and / or mounted essentially centrally between at least two receiving holes for the bone screws, the cervical plate is weakened as little as possible by the support of the disc carrying the locking arms, allowing the cervical plate to be manufactured with an even thinner profile. The thickness is preferably in the range of 1 to 3 mm.

[0029] It has been shown that the thin disc forming the locking body, preferably with a thickness in the fraction of a millimeter (mm), can be equipped with up to four locking arms with suitable material selection, without mechanically overloading the functional sections of the locking body, i.e., the locking arms and the detent mechanism. For secure locking of the inserted bone screws, it may suffice to only partially cover the screw heads. This offers the additional advantage that the screw drive remains accessible even when the locking mechanism is closed, allowing for retightening.

[0030] The range of applications for the cervical plate system can be further expanded by designing the screw heads of the bone screws and / or adapting them to the design of the support surfaces in the cervical plate so that, when screwed in, they protrude only minimally beyond the top and / or bottom of the cervical plate, even at large angles of inclination to the cervical plate.

[0031] Advantageously, the locking pin has a radial distance from the disc's axis of rotation that is only a fraction of the locking arm's length. In other words, the locking mechanism is positioned as close as possible to the locking element's axis of rotation to prevent it from being pried open by the screws. For example, with a locking arm extending radially from 3 to 4 mm, the locking pin has a radial distance of only 1.5 to 2 mm.

[0032] The rotation angle of the disc from the position that allows as much free access as possible to the locking position can be varied within wide limits. Tests have shown that rotation angles in the range between AE2096P-WG-0001

[0033] 7 / 27

[0034] At 10° and 180°, the locking and detent function is permanently ensured. At larger rotation angles, the support section, in the form of a disc ring cutout or segment that is essentially arc-shaped, becomes particularly long, which allows for even better control of the detent mechanism's compliance.

[0035] Tests have shown that the locking and latching functions described above can be reliably ensured multiple times even with a disc thickness between 0.25 and 0.75 mm. This results in a very flat system overall, which further helps to prevent potential tissue irritation or swallowing difficulties.

[0036] With the design described above, the disc can be moved into and out of the locking position manually, preferably using an operating tool such as a screwdriver. This is advantageous for surgical techniques where screwdrivers are already used to actuate bone screws. It has been shown that small drive profiles in the disc are suitable for reliably transmitting the required torque; for example, wrench sizes of less than 2 mm, such as 1.5 mm.

[0037] Particular manufacturing and operational advantages arise when the disc forms a rotary bearing via a hollow cylindrical bearing journal, preferably integrally molded and received in a bore of the cervical plate with a clearance fit. The wall thickness of this journal tapers progressively towards its end section facing the rear of the cervical plate, where it is preferably riveted to the cervical plate via a chamfer on the bore. Riveting between the cervical plate and the locking element is particularly cost-effective, as the deformation or plastic deformation of the locking element during riveting can be well-defined and limited by the chamfer on the underside of the cervical plate. Furthermore, this method automatically cannulates the locking elements to allow a temporary fixation pin to secure the cervical plate to a vertebral body.Simultaneously, the hollow cylindrical section of the locking body can be equipped with a drive profile, preferably with a polygonal recess for the engagement of an operating tool. This polygonal recess can extend over a length that essentially corresponds to the thickness of the cervical plate, so that its wrench size can be kept very small without having to fear excessive wear.

[0038] If the multi-sided recess has a width smaller than the width of a clamping cone on the screwdriver for the bone screw or of a clamping area (inner cone) of the corresponding bone screws, the particular advantage arises that both the bone screws and the locking mechanisms can be operated with the same screwdriver. The screwdriver can thus function as a multi-functional instrument with one working end performing three functions: holding the bone screw via a conical clamp, screwing in the screw via a star profile, and locking the locking mechanism with a smaller drive profile, such as a hexagon.

[0039] When the disc is received in a shallow recess on the upper surface of the cervical plate, it protrudes a correspondingly smaller amount from the surface, further benefiting the flat design of the cervical plate system. This protrusion can be reduced even further if the axis of rotation of the locking element is not perpendicular to the surface of the cervical plate, but rather inclined at an angle of a few degrees, preferably between 3 and 7°, to the surface normal.

[0040] It is sufficient if the locking pin only has a height in the range between 0.25 and 0.75 mm.

[0041] A particularly material-saving design of the locking element is achieved when it is manufactured using MIM (Metal Injection Molding), preferably from a Ti6Al4V (according to DIN EN ISO 5832-3) or CoCr alloy. With this material selection, sufficient strength and a suitable locking mechanism can be achieved even with a very thin locking element disc.

[0042] Several embodiments of the new system with an anterior cervical plate and a locking mechanism for inserted bone screws, which are screwed into a vertebral body and press the cervical plate against the vertebral body, are described in more detail below using schematic drawings. The drawings show:

[0043] Brief description of the characters

[0044] Fig. 1 shows a bottom view of a first embodiment of an anterior cervical plate with mounted locking bodies for inserted bone screws, wherein the cervical plate is designed as a hybrid 2-segment plate;

[0045] Fig. 2 shows the side view of the cervical plate shown in Figure 1;

[0046] Fig. 3 shows the top view of the cervical plate with the locking elements mounted;

[0047] Fig. 4 shows the sectional view according to IV-IV in Figure 3;

[0048] Fig. 5 shows a top view of a system with a locking mechanism according to Figs. 1 to 4, but with modified locking bodies and a cervical plate designed as a dynamic 2-segment plate;

[0049] Fig. 6 shows the view of the system according to Fig. 5 from below;

[0050] Fig. 7 shows the side view of the system according to Fig. 5 from below;

[0051] Fig. 8 shows a perspective view of the system according to Figs. 5 to 7 with the screw tool in use; AE2096P-WQ-0001

[0052] 10 / 27

[0053] Fig. 9 shows a top view of a modified embodiment of a dynamic cervical plate with modified locking bodies and a representation of a screw in different angular orientations;

[0054] Fig. 10 shows the side view of the cervical plate according to Fig. 9;

[0055] Fig. 11 shows a top view of another embodiment of the system with a modified cervical plate and a modified locking body;

[0056] Figs. 12 to 14 show in enlarged detail the top view (Fig. 12), section XIII-XIII (Fig. 13) and the bottom view (Fig. 14) of a cranial receiving orifice of a so-called hybrid cervical plate;

[0057] Figs. 15 to 17 show in enlarged detail the top view (Fig. 15), section XVI-XVI (Fig. 16) and the bottom view (Fig. 17) of a central receiving orifice of a hybrid cervical plate;

[0058] Figs. 18 to 21 show in enlarged detail the top view (Fig. 18), two sectional views XIX-XIX and XXI-XXI (Fig. 19 and Fig. 21) and the bottom view (Fig. 20) of a cranial receiving orifice of a so-called dynamic cervical plate;

[0059] Figs. 22 to 25 show in enlarged detail the top view (Fig. 22), two sectional views XXII l-XXII I and XXV-XXV (Figs. 23 and 25) and the bottom view (Fig. 24) of a central receiving orifice of the dynamic cervical plate;

[0060] Fig. 26 shows a top view of another embodiment with a modified cervical plate;

[0061] Fig. 27 is an enlarged sectional view according to XXVII-XXVII in Fig. 26;

[0062] Fig. 28 shows an enlarged view of detail XXVIII in Fig. 27; Fig. 29 shows a perspective view of the cranial receiving orifices with the associated different bone screws;

[0063] Fig. 30 in enlarged view a perspective view of a cervical plate system with modified locking body;

[0064] Fig. 31 shows the top view of the locking body according to Figure 30;

[0065] Fig. 32 shows the side view of the locking body according to Fig. 30; and

[0066] Fig. 33 shows the view of the locking body according to Figure 30 from below.

[0067] Description of the exemplary implementations

[0068] The following are examples of embodiments of the present disclosure based on the accompanying figures.

[0069] First embodiment

[0070] Figures 1 to 4 show a first embodiment of a system with an anterior cervical plate 10 having six approximately circular receiving openings 12 for bone screws (not shown) and a locking mechanism for inserted bone screws that are screwed into a vertebral body and press the cervical plate against the vertebral body. In addition to the approximately circular receiving openings 12, the cervical plate 10 also has two windows 14.

[0071] The illustration shows that the central receiving holes are designed differently with respect to their bearing surfaces for the bone screws compared to the cranial and dorsal receiving holes 12K and 12D, respectively. Details of this design are described below with reference to Figures 12 to 17.

[0072] The contact surfaces for the heads of the bone screws are not specified in detail; they are described in more detail below with reference to Figures 12 to 17, and they are AE2096P-WQ-0001

[0073] 12 / 27 is designed such that—as can be seen from Figures 12 to 17—it consists of a spherical surface in combination with a conical surface, which allows the use of both angularly constrained and angularly variable screws. The cervical plate 10 shown thus represents a so-called 2-segment hybrid plate, in which translational screw slippage is prevented. Alternatively, the contact surfaces can also consist of only a spherical surface or only a conical surface.

[0074] In a manner known per se, the cervical plate 10 is pre-bent longitudinally and slightly curved transversely in order to conform as closely as possible to the shape of the cervical spine.

[0075] The cervical plate 10 is equipped with a locking mechanism for the bone screws inserted and screwed into the cervical vertebrae, which will be described in more detail below. This locking mechanism prevents the bone screws from migrating out of the plate.

[0076] The locking mechanism must be designed such that a locking body 16 can be moved from a position that leaves a receiving opening 12 as freely accessible as possible into a locking position in which the screw head lying in the receiving opening 12 is at least partially covered by the locking body 16 and thus the migration of the screw out of the cervical plate 10 is prevented.

[0077] In the illustrated embodiment, three locking elements 16 are provided, each assigned to two adjacent receiving openings 12 and each arranged substantially centrally between two adjacent receiving openings 12. Each locking element 16 is formed by a thin disk 16 rotatably fixed to the anterior cervical plate 10 about a rotation axis A16 located substantially perpendicular to the cervical plate 10. The disk 16 has at least one locking arm 18-1 and 18-2 distributed angularly around its circumference and a support section 20 lying in the plane of the disk and extending by a central angle. By rotating the disk 16 by a predetermined rotation angle WD, which is indicated in Figure 3 between the two dashed lines and corresponds substantially to the central angle of the support section 20, the support section 20 snaps from the open position shown in Figure 3 into a detent position that locks the bone screws.

[0078] The rotatability of the disk 16 is provided by a bearing journal 22, preferably formed integrally with the disk 16, which is received with clearance in a bore 24 of the cervical plate 10. The bearing journal 22, with a diameter and length that essentially correspond to the thickness D10 (see Fig. 4) of the cervical plate 10, is formed in a hollow cylindrical shape such that its wall thickness tapers progressively towards its end section facing the rear of the cervical plate, i.e., away from the disk 16, via a widening internal cone 26, and is riveted to the cervical plate 10 there via a chamfer 28 of the bore 24. The locking body in the form of a disc 16 with a hollow bearing pin 22 is cannulated in this way, which can be used to pull the bearing pin 22 as a guide for a temporary fixation pin to fix the cervical plate 10 to the spine.

[0079] The dimensions of the disc 16 are selected such that they only minimally increase the overall thickness of the cervical plate system. For example, the thickness D16 (see Fig. 4) of the disc 16, if the thickness D10 of the cervical plate 10 is between 1 and 3 mm, preferably between 1.5 and 2.5 mm, is in the range of 0.25 and 0.75 mm. The diameter D22 of the bearing journal 22, in this case, is in the range of 1.2 and 3.5 mm.

[0080] The overall thickness of the cervical plate system can be reduced somewhat further by accommodating the disc 16 in a shallow depression on the upper side of the cervical plate 10.

[0081] To provide a locking mechanism integrated into the cervical plate system for the locking body 16 in question, the support section 20 interacts with a locking pin 30 mounted on the cervical plate 10, as in the AE2096P-WQ-0001

[0082] 14 / 27

[0083] Rotating the disc 16 deforms the support section 20 before reaching the detent position, before the disc 16 snaps into the detent position.

[0084] The locking pin 30 can have a wide variety of shapes, which will not be discussed in detail here. Its radial extent, for example, is between 0.5 and 1.5 mm, and its height essentially corresponds to the thickness D16 of the disk 16.

[0085] The support section 20 is formed – as shown in Figure 3 – by a substantially arc-shaped disc ring cutout, which, when the disc 16 is rotated from the position shown in Figure 3, is deformed radially by the locking pin 30 and, upon reaching the locking position (not shown), preferably snaps flatly onto the locking pin 30 with a locking recess 32. In other words, the locking pin 30 is caught in an arc-shaped recess 34 in which it can initially move with some play when the disc 16 is rotated, before running up against a projecting lug 36 before reaching the locking recess 32, thereby bending the disc ring cutout outwards. For this purpose, the disc ring cutout has a small radial extent ER (see Figure 11), i.e., a small wall thickness, which can be in the range of a fraction of a millimeter.

[0086] As soon as the disc 16 continues to rotate and passes the lug 36, the disc ring cutout SRA snaps onto the locking pin 30 and engages with it via the locking recess 32. In this position, the disc 16 has reached the locking position that secures the bone screws, in which the locking arms 18-1 and 18-2 are pivoted over the receiving openings 12 and partially cover them. The locking recess 32 is adapted to the cross-section of the locking pin in terms of its shape and position, so that opening requires a specific torque and can be done manually.

[0087] To enable the locking element described above, in the form of the disc 16 with bearing pin 22, to be manufactured with minimal production effort, it is advantageous to produce it using the MIM (Metal Injection Molding) process, preferably from a Ti6Al4V (according to DIN EN ISO 5832-3) or CoCr alloy. AE2096P-WQ-0001

[0088] 15 / 27

[0089] Details of the design of the locking pin 30 are not shown in the figures. Preferably, a cross-section is chosen that facilitates sliding within the cam 34 and is geometrically adapted to the locking recess 32 such that the disc 16 can be moved smoothly into and out of the snap position, while at the same time ensuring that the operator can feel the engagement of the locking position. The locking state is thus clearly recognizable both haptically and visually.

[0090] This makes it clear that the entire rotation angle WD can be used to provide the deformation. A spring element is thus provided, which allows tolerances on the cervical plate 10 and on the locking body, i.e., the disc 16, to be compensated for without negatively affecting the torques required for locking and unlocking.

[0091] This design of the locking mechanism improves the ease of use of the locking body. The disc 16 can be easily moved into and out of the locking position by hand, preferably using an operating tool such as a screwdriver, and the drive used to rotate the disc 16 is dimensioned such that locking does not impair its function, because the deflection or deformation of the locking mechanism operates in a radial direction.

[0092] A tool is used to rotate the disc 16, which interacts with a polygonal recess 42 in the bearing journal 22. Due to the relatively small rotational forces required, the polygonal recess 42 only needs to have a depth T42 (see Fig. 4) in the millimeter range. Furthermore, the polygonal recess 42 can be designed with a small width, also in the millimeter range, and thus smaller than the width of any clamping cone for the bone screws that may be formed on the screw tool. AE2096P-WG-0001

[0093] 16 / 27

[0094] The rotation angle WD in the illustrated embodiment is approximately 50 to 60°. However, it has been shown that this rotation angle WD can vary within wide limits and can lie in the range between 10° and 180°.

[0095] Another special feature of the new locking mechanism is its very small footprint. As best seen in Figure 3, the locking pin 30 has a radial distance from the axis of rotation A16 of the disk 16 that is only a fraction of the length L18 (see Figure 4) of the locking arm 18-1 or 18-2. This arrangement allows the receiving openings 12 and the windows 14 in the cervical plate 10 to be made as large as possible, with the additional advantage of preventing them from being pried open by the bone screws.

[0096] In the embodiment described above, the locking concept is implemented in a so-called hybrid cervical plate 10 with disc-like locking bodies 16, which have two locking arms 18-1 and 18-2.

[0097] However, the innovative locking concept is uniformly applicable to hybrid and so-called dynamic plates, which is described in more detail below with reference to Figures 5 to 8, 9 and 10 and Figure 11.

[0098] Second embodiment

[0099] Figures 5 to 8 show a second embodiment of a cervical plate system. For the sake of simplicity, components corresponding to the parts and sections of the first embodiment are identified by reference numerals preceded by a "1".

[0100] The cervical plate 110 of this embodiment is designed as a so-called dynamic two-segment plate, in which the six receiving openings 112 are formed by elongated holes designed to receive so-called variable screws 150 with spherical screw heads. In this embodiment as well, the central receiving openings 112Z are designed differently with respect to their bearing surfaces for the bone screws 150 compared to the cranial and dorsal receiving openings 112K and 112D, respectively. Details of this design are described below with reference to Figures 18 to 25.

[0101] It can be seen from the illustration according to Figures 7 and 8 that the bone screws 150 can be inserted at very large angles of inclination WN (see Figure 7) to the cervical plate 110 and screwed to the vertebral body in question by means of a screw tool 90 and a star profile 152 in the screw head, without the screw head protruding significantly from a top surface of the cervical plate 110.

[0102] In this embodiment, the cervical plate 110 is combined with modified locking bodies, which are again designed as a disk 116, but with only one locking arm 118.

[0103] Third example

[0104] Figures 9 and 10 show another embodiment of a cervical plate system. To simplify the description, components corresponding to the parts and sections of the first embodiment are again identified by reference numerals preceded by a "2".

[0105] The cervical plate 210 corresponds essentially in shape to the cervical plate 110 of the second embodiment. However, the locking elements 216, which are designed as discs, are configured with differently shaped locking arms 218, 218-1, and 218-2. In Fig. 10, reference numerals 250 and 250* indicate the angle at which the screws can be inserted into the through-holes 212. Each through-hole accommodates only a single screw. The two screws in one through-hole in AE2096P-WG-0001

[0106] Figures 9 and 10 show the permissible angular range in which the screws can be inserted.

[0107] Fourth embodiment

[0108] Figure 11 shows another embodiment of a cervical plate system. To simplify the description, components corresponding to the parts and sections of the first embodiment are again identified by reference numerals preceded by a "3".

[0109] Here, a hybrid single-segment plate 310, i.e., a cervical plate with only four receiving openings 312, is used, to which a single, disc-shaped locking element 316 is assigned. In this case, the cervical plate 210 does not have central receiving openings, but rather two cranial and two dorsal receiving openings 312K and 312D, respectively.

[0110] The locking element 316 is designed as a disc with four locking arms 318-1 to 318-4, which are largely identical in shape. In the locking position shown, the receiving openings 312 are partially covered by the single locking element 316. This partial coverage is sufficient to hold the inserted bone screws, one of which, bone screw 350, is shown in Figure 11, in their position and to prevent them from migrating out of the cervical plate 310. At the same time, Figure 11 shows that the partial coverage of the receiving openings 312 means that the drive mechanism of the bone screws 350, in the form of a suitable screw drive profile, such as a star profile 352, remains accessible, thus allowing the screws to be tightened even in the locked position of the locking arms 318.

[0111] In contrast to the embodiments described above, the cervical plate 310 carries two locking pins 330 which interact with two support sections 320 positioned symmetrically to each other. AE2096P-WG-0001

[0112] 19 / 27

[0113] The locking pins 330 are also essentially identical in their position relative to the axis of rotation A316 to those of the first embodiment, so that a more detailed description is unnecessary. When the locking body 316 pivots, the locking pin 330 deforms the support section 320 with thickness ER before reaching its locking end position.

[0114] Design of the receiving openings and the bone screws

[0115] Figures 12 to 17 show the designs of the receiving openings for the hybrid cervical plates, with figures 12 to 14 showing the cranial and figures 15 to 17 showing the central receiving openings.

[0116] To maximize flexibility in the use of the described cervical plate systems, the receiving openings in the hybrid plates are designed as follows:

[0117] The sectional views in Figures 13 and 16 show that, in both the cranial and central receiving openings, the bearing surfaces for the bone screws form a conical surface 62 with a cone angle WK62 following a circular cylindrical opening 60, to which a spherical surface 64 adjoins. Thus, both rigid screws with a conical screw head and variable screws with a spherical head can be used in the hybrid plate, as will be explained in more detail below with reference to Figures 26 to 29.

[0118] This design of the bearing surfaces also applies to the receiving openings in the dynamic plates, which are prepared to accommodate the variable screws.

[0119] This design is shown in Figures 18 to 21 for the cranial and in Figures 22 to 25 for the central receiving openings.

[0120] Figures 27 and 28 illustrate how variable and constrained screws are supported on the bearing surfaces of the mounting holes in a hybrid plate. This is demonstrated using an AE2096P-WG-0001 as an example.

[0121] 20 / 27

[0122] Cross-sectional view through the cranial imaging openings of a hybrid 5-segment plate 410 shown.

[0123] The variable screw 50V has a screw head with a spherical support section 70V, which is supported on the spherical surface 64.

[0124] The constrained screw, designated 50R, i.e., an angularly restricted screw with a conical support section 70R, is supported by the conical surface 62. To facilitate manual insertion of the bone screw at the intended angles in clinical applications, the screw head of the constrained screw and the spherical support section, i.e., the spherical surface 64 within the plate, are designed and adapted to each other such that there is a small clearance S between a round surface 65 of the screw head located below the conical surface 62 and the spherical surface 64 in the plate.

[0125] Figure 29 shows a perspective view of the cervical plate 10 according to Figures 1 to 4, illustrating how a variable screw 50V and a rigid screw 50R are supported in the cranial receiving openings 12K. The conical support section 70R makes contact with the hatched area FR, while the spherical support section 70V is supported by the lower hatched area FV.

[0126] Other variants:

[0127] In principle, the support section with which the locking pin interacts can be located at various points on the disk. For example, it can be formed by a disk section that rests on a locking pin mounted on the cervical plate and located beneath the disk section. When the disk is rotated, i.e., when the disk section moves over the locking pin, the support section deforms perpendicular to the disk plane before snapping into the locking position.

[0128] The foregoing describes locking elements in the form of discs having an axis of rotation perpendicular to the cervical plate. AE2096P-WQ-0001

[0129] 21 / 27

[0130] However, the axis of rotation A16 can also be pivoted by just a few degrees, for example by 5°, in order to reduce the projection of the locking arms of the disc-shaped locking body, which are rotated into the locking position, over the cervical plate.

[0131] The locking mechanism can also be varied. One variation is shown in Figures 30 to 33. To simplify the description, components corresponding to the parts and sections of the first embodiment are again identified by reference numerals preceded by a "4".

[0132] The locking element is again designed as a disk 416, movably mounted about a pivot axis A416 in a cervical plate, with bearing pins 422 and two locking arms 418-1 and 418-2. However, the support section 420, designed as a disk ring cutout and intended for functional engagement with the locking pin 430, extends over a larger central angle WZ420 (see Figure 33) of almost 180° compared to the embodiments described above, resulting in an even greater length of the deformable support section 420. In this case, the locking pin 430 is not trapped in a cam. Instead, when the disk 416 is pivoted into the locking position shown in Figure 30, the locking pin 430 moves, preferably with minimal play, along the outer side of the deformable support section 420 relative to the disk 416.The deformable support section forms a radially outwardly directed, rounded nose 436 (see Figures 31 and 33), whereby the support section 420 is deformed radially inwards before reaching the locking position and springs back when rotating further into the locking position, in which the locking pin - as shown in Figure 30 - rests in a locking recess 472.

[0133] When the disc 416 is rotated into the open position, the nose 436 initially moves under the locking pin 430, briefly deforming the support section 420. The disc can then be pivoted almost effortlessly over the centering angle WZ420 until the locking pin 430 reaches a stop 474 or a stop recess. In this position, the two locking arms 418-1 and 418-2 are pivoted far enough that they no longer overlap the receiving openings. AE2096P-WQ-0001

[0134] 22 / 27

[0135] Of course, variations of the described embodiments are possible without abandoning the basic idea of ​​the innovation.

[0136] The locking pin of the locking mechanism can also have a symmetrical (e.g. circular) or asymmetrical (composed of circular segments and straight lines, e.g. teardrop-shaped) cross-section.

[0137] The innovation thus creates a system with an anterior cervical plate with receiving openings for bone screws and a locking mechanism for inserted bone screws that are screwed into a vertebral body and press the cervical plate against the vertebral body, wherein the locking mechanism has a plate-like locking body that is movably held on the cervical plate and can be moved from a position that allows as much free access as possible to a locking position in which the screw head lying in the receiving opening is covered by the locking body and thus prevents the screw from migrating out of the cervical plate.In order to design the system to be easy to use while maintaining a high level of security against loosening of the bone screws and to offer maximum flexibility in the design of the cervical plate for a wide range of treatment options, the locking body is uniformly formed for cervical plates for hybrid and dynamic treatment options by a thin disc rotatably fixed to the anterior cervical plate about an axis of rotation (A16) that is substantially perpendicular to the cervical plate, which has at least one locking arm and a support section angularly distributed around its circumference, which is part of a ratchet mechanism.

[0138] Reference symbol list

[0139] 10 cervical plate

[0140] 12, 12K, 12Z recording breakthroughs

[0141] 14 windows

[0142] 16, 16* Locking body (disc) A16 Pivot axis

[0143] D16 Thickness of 16

[0144] 18, 18-1, 18-2 locking arms

[0145] L18 Length of 18

[0146] 20 Support section

[0147] 22 bearing journals

[0148] 24 bore

[0149] 26 Inner cone

[0150] 28 Chamfer

[0151] 30 locking pins

[0152] 32 Resting recess

[0153] 34 Scenery

[0154] 36 Nose

[0155] 42 Multi-sided recess

[0156] T42 Depth of 42

[0157] 50 bone screws

[0158] 50R rigid screw

[0159] 50V variable screw

[0160] 52 Star Profile

[0161] 60 opening

[0162] 62 cone surface

[0163] 64 Spherical surface

[0164] 65 round area

[0165] WK62 cone angle of 62

[0166] 64 Spherical surface

[0167] 70V spherical support section

[0168] 70R conical support section

[0169] 90 screwdrivers

[0170] ES disk plane

[0171] FR support surface of a rigid screw

[0172] FV support surface of a variable screw

[0173] WN tilt angle

Claims

AE2096P-WG-0001 24 / 27 Game Claims 1. System with an anterior cervical plate (10) with receiving openings (12) for bone screws (50, 50V, 50R) and a locking mechanism for inserted bone screws (50, 50V, 50R) screwed into a vertebral body and pressing the cervical plate against the vertebral body, wherein the locking mechanism has a plate-like locking body movably held on the cervical plate, which can be moved from a position allowing as much free access as possible to a receiving opening (12) into a locking position in which the screw head located in the receiving opening (12) is covered by the locking body and thus prevents the screw from migrating out of the cervical plate, characterized in thatthat the locking body is uniformly formed for cervical plates (10) for hybrid and dynamic supply options by a thin disc (16) rotatably fixed to the anterior cervical plate about a rotation axis (A16) perpendicular to the cervical plate (12), which has at least one locking arm (18, 18-1, 18-2) and a support section (20) distributed angularly around its circumference, which is part of a locking mechanism.

2. System according to claim 1, wherein the locking mechanism is designed such that the disk (16) can be brought into its locking position by rotating it by a predetermined angle of rotation (WD), which represents a locking position that can be released by counter-rotating the disk (16).

3. System according to claim 1 or 2, characterized in that the support section (20) is equipped with a component mounted on the cervical plate (10). The locking pin (30) interacts, which, when the disc (16) is rotated, deforms the support section (20) before reaching the locking position.

4. System according to one of claims 1 to 3, characterized in that the support section (20) is formed by a substantially arc-shaped disc ring cutout which, when the disc (16) is rotated, is deformable in a radial direction by the locking pin (30) and forms a locking recess (32) for the locking pin (30).

5. System according to one of claims 1 to 4, characterized in that the receiving openings (12) for the bone screws (50, 50V) in the area of ​​their support surfaces for the bone screws consist of a spherical surface (64) in combination with a conical surface (62).

6. System according to one of claims 1 to 5, characterized in that the receiving openings (12) are designed to receive and support so-called constrained screws (50R) with a conical screw head (70R) as well as so-called variable screws (50V) with a spherical screw head (70V).

7. System according to one of claims 1 to 6, characterized in that the locking body is arranged substantially centrally between at least two receiving openings (12) for the bone screws (50).

8. System according to one of claims 1 to 7, characterized in that the disc (16) has up to four locking arms (18) with which the heads of the inserted bone screws (50) can be partially covered.

9. System according to one of claims 5 to 8, characterized in that the screw heads (70V, 70R) of the bone screws (50V, 50R) are designed and / or adapted to the design of the support surfaces (62, 64) in the cervical plate (10) such that, in the screwed-in state, they protrude only minimally beyond the top and / or bottom of the cervical plate (10), even at large angles of inclination (WN) to the cervical plate (10).

10. System according to one of claims 1 to 9, characterized in that the disk (16) has a thickness (D16) in the range between 0.25 and 0.75 mm.

11. System according to one of claims 1 to 10, characterized in that the anterior cervical plate (10) has bores and / or elongated holes as receiving openings (12) for the bone screws (50).

12. System according to one of claims 1 to 11, characterized in that the locking element (disc 16) is manufactured using the MIM (Metal Injection Molding) process, preferably from a Ti6Al4V or CoCr alloy.

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