Osteosyntheseplatte

Abstract

1. Osteosynthesis plate (OP; OP'; OP''; OP'''), which is intended for fixing bone fragments (K1, K2) for the reconstruction of a bone (K), in particular a mandible, comprising a plate body (P; P') with a top (OS) and a bottom, on which the plate body (P; P') is to be placed on the bone fragments (K1, K2), wherein the plate body (P; P') has several attachment sections (BA1, BA2; BA1', BA2', BA3'), on which attachments of the osteosynthesis plate (OP; OP'; OP''; OP''') are to be made on the underside by the bone fragments (K1, K2) and to which at least one attachment point (BP1, BP2; BP1', BP2', BP3') is assigned, wherein the at least one attachment point (BP2; BP2', BP3') is located at at least one of the attachment sections (BA1, BA2; BA1', BA2', BA3') is designed on an island section (IA) which is connected to the associated fastening section (BA2; BA2', BA3') of the plate body (P;P') is connected exclusively via spring segments (FS1, FS2) which allow a relative displacement of the respective mounting section (BA2; BA2', BA3') and the respective island section (IA) to each other in an elastically resilient manner, wherein the spring segments (FS1, FS2) surround their assigned mounting point (BP2, BP2', BP3') asymmetrically.;

Description

The invention relates to an osteosynthesis plate designed for fixing bone fragments to reconstruct a bone, in particular a mandible. The plate body comprises a plate body with a top and a bottom surface on which the plate body is to be placed against the bone fragments. The plate body has at least one bridge section for bridging a gap between the bone fragments, and the plate body is equipped with fastening sections located on both sides of the at least one bridge section. The osteosynthesis plate is to be attached to the bone fragments on its underside by means of the fastening sections. For this purpose, each fastening section is assigned at least one fastening point, wherein the at least one fastening point is configured on an island section in at least one of the fastening sections.The island section is connected to its respective mounting section exclusively via spring segments, which allow a relative displacement of the respective mounting section and the respective island section to each other in an elastically springy manner. Osteosynthesis involves surgically joining two or more bone fragments to promote fusion and thus restore the bone. The goal of osteosynthesis is to stabilize the bone fragments relative to each other, ensuring they are in the correct position and, if necessary, correcting any malalignment. In addition to fixation with wires or screws, osteosynthesis plates are also used, depending on the application. The plate is placed on the bone within the gap between the fragments and attached to the bone fragments being joined. In addition to stabilizing bone fragments after a bone fracture, osteosynthesis plates are sometimes used when a bone segment resected from another location needs to be inserted into an existing defect in the bone and stabilized to restore bone function. Such a defect may have arisen, for example, due to the necessary removal of a portion of the bone following a tumor. Regarding the healing process of the respective bone, it has proven advantageous if the bone fragments of the bone to be reconstructed are not rigidly connected to each other via the respective osteosynthesis plate, but rather if micro-movements between the bone fragments are allowed. To enable these micro-movements, the attachment points on at least one of the bone fragments to be connected are linked via spring segments. WO 2011 / 163387 A2 describes a bone fracture fixation plate with an outer surface and a surface facing the bone. The bone plate has slots extending through the plate from the outer surface to the surface facing the bone. The slots at least partially circumscribe the circumference of one or more receiving holes and do not extend through a longitudinal edge of the bone plate. The slots form a spring element that at least partially surrounds the receiving hole and allows axial displacement of the bone plate relative to the one or more receiving holes within a plane parallel to an upper or lower surface of the bone plate, but prevents movement of the bone plate relative to the one or more receiving holes in a direction perpendicular to the upper surface of the bone plate. Starting from the prior art described above, the object of the present invention is to create an osteosynthesis plate in which a variable arrangement of attachment points that can be moved relatively via spring segments can be achieved. This problem is solved starting from the preamble of claim 1 in conjunction with its characterizing features. The subsequent dependent claims each describe advantageous embodiments of the invention. Further advantageous embodiments will become apparent from the description and the figures. According to the invention, an osteosynthesis plate, designed for fixing bone fragments to reconstruct a bone, comprises a plate body with a top and a bottom surface on which the plate body is placed against the bone fragments. The plate body has several attachment sections to which the osteosynthesis plate is attached on the underside by the bone fragments, and each section is assigned at least one attachment point. The at least one attachment point is configured on an island section in at least one of the attachment sections. This island section is connected to the corresponding attachment section of the plate body exclusively via spring segments, which allow elastic displacement between the respective attachment section and the respective island section. The osteosynthesis plate according to the invention is designed for fixing bone fragments to reconstruct a bone. This bone reconstruction can, within the scope of the invention, be achieved in two ways: firstly, by fixing bone fragments that have formed as a result of a bone fracture to one another using the osteosynthesis plate. In this case, the bone fragments belonging to the bone to be reconstructed are fixed and stabilized relative to each other by the osteosynthesis plate. Secondly, the invention also considers bone reconstruction to include closing a defect in a bone with a bone segment resected from another bone for this purpose. Accordingly, in this case, the respective bone is reconstructed from its own bone fragments and a bone fragment belonging to another bone.In this case, the osteosynthesis plate according to the invention serves to fix the resected bone segment closing the defect to at least one of the bone segments located on either side. The osteosynthesis plate is particularly preferred for use in the region of the mandible, where it can then be used either for the reconstruction of a bone fracture or for closing a bone defect. The osteosynthesis plate is equipped with a plate body, which is preferably elongated, i.e., extends at least predominantly in a longitudinal direction. The plate body can extend along a longitudinal axis running in this direction or be designed to run along a guide curve oriented in this longitudinal direction. The plate body has a top and a bottom surface, which are oriented away from each other. When using the osteosynthesis plate according to the invention, the plate body is placed on the bone fragments on its underside, bridging at least one gap between the bone fragments to be fixed. Furthermore, the underside of the plate body provides a means of securing the bone fragments to be fixed. For this purpose, the plate body is equipped with several fastening sections. Each fastening section has at least one fastening point, preferably formed by a through-hole through which a bone screw can be inserted.The bone screw is used to attach the device to the respective bone fragment. In at least one of the mounting sections of the plate body, the at least one provided mounting point is configured on an island section, which is connected to the associated mounting section exclusively via spring segments that couple the respective island section to the associated mounting section. These spring segments allow an elastic displacement of the island section relative to the associated mounting section, whereby, in the sense of the invention, it is understood in particular that the spring segment deforms elastically during a relative displacement that the island section and the associated mounting section undergo relative to each other under load and deforms back to its initial position when the load is removed. Preferably, the spring segment is configured as a spring leg that extends at least largely linearly. Preferably, the spring segments allow relative displacement between the island section and the attachment section only largely parallel to the upper and lower surfaces and / or in the longitudinal direction. This is because, due to the shape of the plate body, the bridging of the respective gap between the bone fragments also occurs in this direction. Relative displacements oriented in this direction result in changes to the gap width, which has proven advantageous with regard to the healing process of the bone being reconstructed. The respective island section is preferentially positioned on the underside of the plate body relative to the corresponding attachment section. This ensures that when the osteosynthesis plate is attached to the respective bone fragment, it rests against the island section while simultaneously allowing the bone fragment free movement relative to the attachment section. This prevents frictional interference with the relative movement between the island section and the attachment section, as the attachment section also rests on the bone fragment, which is likewise movable relative to the attachment section. The osteosynthesis plate is preferably manufactured using an additive manufacturing process, preferably a 3D printing process. The osteosynthesis plate is preferably made of titanium, a titanium alloy, stainless steel, or a suitable polymer such as polyetheretherketone (PEEK). The invention now comprises the technical teaching that the spring segments surround their assigned attachment point asymmetrically. This design of an osteosynthesis plate has the advantage that the asymmetrical shapes of the spring segments allow for a compact design of the island section on the associated attachment section. For example, if an island section is located at one end of the plate body, the spring segment on that end can be designed differently from the opposite spring segment, enabling the island section to be positioned as close as possible to the end of the plate body. If the attachment section has several attachment points formed on island sections, the asymmetrical shapes of the individual spring segments allow for a denser arrangement of these island sections. Thus, the design according to the invention allows for greater variability in the arrangement of the attachment points, so that the arrangement can be optimally adapted to the anatomy. According to one possible embodiment of the invention, the island section is connected to the respective mounting section via exactly two spring segments. In this case, exactly two spring segments couple the respective island section to the associated mounting section. However, the invention could also provide for more than two spring segments to connect the respective island section to the associated mounting section. According to a further embodiment of the invention, the island section and the associated spring segments are formed by openings provided in the respective attachment section. Advantageously, this allows for a one-piece design of the plate body, as the island section and the spring segments are defined by creating the openings in the plate body at the respective attachment section. If the plate body of the osteosynthesis plate is manufactured using an additive manufacturing process, the openings can also be formed during this additive manufacturing process. Alternatively, the openings can also be defined by abrasives or machining. The openings can be U-shaped, with the openings facing each other and nested within one another. This allows for a particularly space-saving design of the respective island section and the associated spring segments, further improving the flexibility of the attachment point arrangement. In another possible embodiment of the invention, a first of the spring segments is oriented orthogonally to a longitudinal direction of the mounting section. This orientation of the spring segment allows the associated island section to be positioned close to one end of the associated mounting section or adjacent to another island section of the associated mounting section. According to a further embodiment of the invention, several fastening points are assigned to each fastening section, with each fastening point being designed on an island section with spring segments arranged asymmetrically around the respective fastening point. This allows the multiple fastening points to be arranged compactly relative to each other in this fastening section, thus further improving the variability of the fastening point arrangement. Preferably, a second of the spring segments is oriented at an acute angle to a direction that is orthogonal to a longitudinal direction of the attachment section. This allows a relative displacement of the island section to be brought about by means of this acutely oriented spring segment when the attachment section is subjected to a transverse load or when a transverse load is introduced at the attachment point, thus causing a change in the gap between the bone fragments. When combining the two variants described above, the multiple attachment points formed on island sections can be arranged consecutively along the longitudinal direction of the respective attachment section, with adjacent island sections being identical to each other and arranged as point mirrors, such that the adjacent island sections face each other with their acute-angled spring segments. Advantageously, this allows the successive island sections to be arranged extremely compactly next to each other. In a further embodiment of the invention, the fastening sections are arranged in pairs on both sides of an intermediate bridge section, which is designed to bridge a gap running between the bone fragments. In a further development of this embodiment, at least one of the asymmetrically arranged spring segments can be oriented such that, when the bone is loaded in a main load direction, a relative displacement occurs between the respective island section and the respective fastening section, increasing the distance between the respective island section and the bridge section. This has the advantage that, when the bone is loaded in the main load direction, the gap spanned by the bridge section between the bone segments also increases due to the increased distance between the island section and the bridge section.This prevents the gap between the bone segments from becoming zero and the bone segments from touching each other, which would otherwise hinder the healing process of the bone being reconstructed. When inserting a resected bone segment into a defect in the bone being reconstructed, this also prevents a gap between the bone segments from being too small or nonexistent, provided the resected bone segment is designed with a transition fit to the defect. For the purposes of the invention, the "load in the main load direction" of the bone is understood to mean, in particular, a force acting on the bone during its usual stress. Preferably, this load is applied in such a way that a resulting shear force is generated at the corresponding attachment point of the island segment. In the case of the preferred embodiment of the osteosynthesis plate for fixing bone fragments to reconstruct a mandible, the load in the main load direction is a biting force that must be supported via the mandible. According to a further embodiment of the invention, in one of the fastening sections, at least one fastening point is designed to be stationary. In this fastening section, therefore, the one fastening point or the multiple fastening points are designed to be stationary, so that rigid connections to the respective bone segment can be established. Alternatively or additionally, the fastening points for multiple fastening sections are designed on island sections. If none of the fastening sections has a fixed fastening point, then the fastening points for all fastening sections are designed on island sections. Advantageous embodiments of the invention, which are explained below, are illustrated in the drawings. Figures 1A and 1B show schematic representations of a bone with an osteosynthesis plate attached thereto, according to one embodiment of the invention, shown in different states; and Figures 2, 3 to 4 show perspective views of an osteosynthesis plate according to a further embodiment of the invention. Figures 1A and 1B show schematic representations of a bone K with an osteosynthesis plate OP attached to it, where bone K is preferably a mandible. The osteosynthesis plate OP is attached to bone fragments K1 and K2 to stabilize them relative to each other and thereby enable them to fuse together to restore bone K. In this case, bone fragments K1 and K2 may have formed as a result of a fracture of bone K. The osteosynthesis plate is then intended to heal this fracture by stabilizing bone fragments K1 and K2 relative to each other. Alternatively, one of the bone fragments K1 or K2 may have been used to close a defect in bone K, for example, because part of bone K had to be removed at that location due to a tumor. In this case, one of the bone fragments, K1 or K2, is a bone fragment resected from another bone, such as the fibula. The osteosynthesis plate OP has an elongated plate body P, which is preferably made of titanium or a titanium alloy and is manufactured in particular using an additive manufacturing process, preferably 3D printing. The plate body P has a top surface OS, visible in Figs. 1A and 1B, and an opposing, non-visible bottom surface on which the plate body P rests against the bone fragments K1 and K2. The plate body P consists of two attachment sections BA1 and BA2, and a bridge section BU located between them. The plate body P is attached to the bone fragment K1 at attachment points BP1 on the underside of the plate body P. These attachment points are designed as through-holes DO1, extending between the upper surface OS and the underside, and each BP1 accommodates a bone screw (not shown in the figures). The through-holes DO1 are integrated into the attachment section BA1 and are fixed to it. Following the attachment section BA1, the plate body P has a bridge section BU for bridging a gap S. The gap S is located between bone fragments K1 and K2. Attachment section BA2 is formed following the bridge section BU, to which the plate body P is attached from the bone fragment K2. Attachment points BP2 are assigned to attachment section BA2 for this purpose. The attachment points BP2 are also designed as through-holes DO2, which run between the upper surface OS and the lower surface and are intended for the insertion of a bone screw (not shown in the figures) each. Unlike fastening section BA1, the through-openings DO2 in fastening section BA2 are located on island sections IA, which are separated from fastening section BA2. Each individual island section IA is connected to fastening section BA2 exclusively via spring segments FS1 and FS2. The associated spring segments FS1 and FS2 allow elastic relative displacements of the respective island section IA, and thus also of the associated fastening point BP2, relative to fastening section BA2. The spring segments FS1 and FS2, as well as their respective island sections IA, are defined in the OP osteosynthesis plate by openings D1 and D2 in the plate body P. These openings are U-shaped and run from the upper surface OS to the lower surface. Openings D1 and D2 are nested within each other with their U-shaped openings facing each other. This design defines not only the division of the respective island section IA from the fixation section BA2, but also the spring segments FS1 and FS2. The U-shapes of openings D1 and D2 differ in that both have a first leg S11, S12 running transversely to a respective base GS1, GS2 of the U-shape. However, in the U-shape of opening D1, a second leg S21 is angled outwards relative to the base GS1, whereas in the U-shape of opening D2, a second leg S22 is angled inwards.This results in linear and asymmetrical paths for the spring segments FS1 and FS2 relative to the respective mounting point BP2. Due to these asymmetrical paths, the island sections IA provided at the mounting section BA2 can follow each other closely in the same direction. Figure 1A shows an unloaded state of bone K, with the spring segments FS1 and FS2 of the respective island section IA in a basic position, resulting in a gap dimension SM1 with respect to the gap S between bone fragments K1 and K2. In contrast, Figure 1B shows bone K under a load B, which is indicated by an arrow in Figure 1B and represents a typical stress on bone K. In the preferred embodiment of bone K as a mandible, this load B could represent a biting force that needs to be supported. The spring segment FS2 of the respective island section IA runs at an acute angle to a respective force vector KV, which represents a shear force resulting from the load B at the respective attachment point BP2 and is indicated by an arrow in Fig. 1B for one of the attachment points BP2. In addition to this acute angle to the force vector KV (indicated by a dashed line in Fig. 1B), the spring segment FS2 of the island section IA also diverges from the bridge section BU. This results in a force redirection at the spring segment FS2 when the load B is applied to the bone fragment K2. This redirection moves the island sections IA away from the bridge section BU, thereby increasing the distance between the island sections IA and the bridge section BU. This leads to a separation of the bone fragments K1 and K2 and thus an increase in the gap S to a gap dimension SM2.Once the load B ceases, the gap S then reduces again to the gap dimension SM1, as the spring segments FS1 and FS2 of the respective island section IA cause a corresponding displacement through elastic deformation. In general, the relative movement of the bone fragments K1 and K2 to each other promotes the healing process of bone K. The gap dimensions SM1, SM2 in Fig. 1A and Fig. 1B, as well as the deflection of the island segments IA in Fig. 1B, are greatly exaggerated for illustrative purposes. In actual application of the osteosynthesis plate OP, OP', smaller gap dimensions are used, and a typical load B on the bone K would result in a smaller deflection of the island segments IA than shown in Fig. 1B. Figure 2 shows a perspective view of an osteosynthesis plate OP' according to a further embodiment of the invention. In contrast to the variant shown in Figures 1A and 1B, the plate body P' of this osteosynthesis plate OP' has two bridge sections BU1 and BU2 for each bridging a gap (not shown in Figure 2). Thus, three bone fragments of a bone can be stabilized relative to each other via the osteosynthesis plate OP' for the purpose of bone reconstruction. The bridge sections BU1 and BU2 are positioned between the attachment sections BA1', BA2', and BA3', each of which serves to attach one of the bone fragments to the plate. While fastening points BP1' are fixed to the fastening section BA1', fastening points BP2' and BP3' are defined on island sections IA in fastening sections BA2' and BA3', respectively, and are designed analogously to the variant shown in Figures 1A and 1B. In fastening section BA3', the island sections IA, arranged in the same direction, are oriented such that the spring segment FS1 of the island section IA located at one end E of the plate body P' faces this end E. This allows this island element IA, the last one in the chain, to be positioned close to end E. Otherwise, the configuration shown in Figure 2 corresponds to the variant shown in Figures 1A and 1B, and reference is made to the descriptions provided therein. Fig. 3 shows a perspective view of an osteosynthesis plate OP'' according to a further embodiment of the invention. This largely corresponds to the preceding embodiment according to Fig. 2, except that, in contrast to the osteosynthesis plate OP' from Fig. 2, the island sections IA are now arranged in opposite directions in both the attachment section BA2' and the attachment section BA3', by virtue of the spring segments FS2 facing each other in the oppositely directed island sections IA. This allows for an even more compact design of the adjacent island sections IA in the respective attachment sections BA2' and BA3' compared to the embodiment according to Fig. 2. Otherwise, the embodiment according to Fig. 3 corresponds to the embodiment according to Fig. 2, so reference is made to the description therein. Furthermore, Fig. 4 shows a perspective view of an osteosynthesis plate OP''', which is designed according to a further embodiment of the invention and essentially corresponds to the preceding variant according to Fig. 3. The difference is that the plate body P of this osteosynthesis plate OP"''' now only has a bridge section BU and two attachment sections BA1 and BA2 located on either side of it. While the attachment points BP1 of the attachment section BA1 are fixed in position, the attachment points BP2 associated with the attachment section BA2 are formed on island sections IA. In accordance with the preceding variant according to Fig. 3, these island sections IA are oriented in opposite directions, such that the spring segments FS2 of these island sections IA face each other. Otherwise, the embodiment according to Fig. 4 also corresponds to the variant according to Fig. 3.3 , so that reference is made to what is described here. Using the embodiments according to the invention, an osteosynthesis plate can be created in which a compact arrangement of attachment points that can be moved relatively via spring segments is realized. Reference symbol list K Bone OP, OP', OP'', OP''' Osteosynthesis plate K1, K2 Bone fragments P, P' Plate body OS Top side BA1, BA2, BA1', BA2', BA3' Fixation sections BU, BU1, BU2 Bridge section BP1, BP2, BP1', BP2', BP3' Fixation points DO1, DO2 Through openings S Gap IA Island sections FS1, FS2 Spring segments D1, D2 Through openings GS1, GS2 Base sides S11, S12, S21, S22 Legs SM1, SM2 Gap dimensions B Load KV Force vector E End QUOTES INCLUDED IN THE DESCRIPTION This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature WO 2011 / 163387 A2

[0005]

Claims

Osteosynthesis plate (OP; OP'; OP''; OP'''), which is intended for fixing bone fragments (K1, K2) for the reconstruction of a bone (K), in particular a mandible, comprising a plate body (P; P') with a top (OS) and a bottom, on which the plate body (P; P') is to be placed on the bone fragments (K1, K2), wherein the plate body (P; P') has several attachment sections (BA1, BA2; BA1', BA2', BA3'), on which attachments of the osteosynthesis plate (OP; OP'; OP''; OP"') are to be made on the underside by the bone fragments (K1, K2) and to which at least one attachment point (BP1, BP2; BP1', BP2', BP3') is assigned, wherein the at least one attachment point (BP2; BP2', BP3') is located on at least one of the attachment sections (BA1, BA2; BA1', BA2', BA3') is designed on an island section (IA) which is connected to the associated fastening section (BA2; BA2', BA3') of the plate body (P;P') is connected exclusively via spring segments (FS1, FS2) which allow a relative displacement of the respective mounting section (BA2; BA2', BA3') and the respective island section (IA) to each other in an elastically resilient manner, characterized in that the spring segments (FS1, FS2) surround their assigned mounting point (BP2, BP2', BP3') asymmetrically. Osteosynthesis plate (OP; OP'; OP''; OP''') according to claim 1 , characterized in that the island section (IA) is connected to the respective fastening section (BA2; BA2', BA3') via exactly two spring segments (FS1, FS2). Osteosynthesis plate (OP; OP'; OP''; OP''') according to claim 1 or 2, characterized in that the island section (IA) and the associated spring segments (FS1, FS2) are formed by openings (D1, D2) formed on the respective fastening section (BA2; BA2', BA3'). Osteosynthesis plate (OP; OP'; OP''; OP''') according to claim 3, characterized in that the openings (D1, D2) are U-shaped, wherein the U-shaped openings (D1, D2) are designed with their openings facing each other and nested within each other. Osteosynthesis plate (OP; OP'; OP''; OP''') according to at least one of the preceding claims, characterized in that a first of the spring segments (FS1, FS2) is oriented orthogonally to a longitudinal direction of the fastening section (BA2; BA2', BA3'). Osteosynthesis plate (OP; OP'; OP''; OP''') according to at least one of the preceding claims, characterized in that several attachment points (BP2; BP2', BP3') are assigned to the respective attachment section (BA2; BA2', BA3'), wherein each of the attachment points (BP2; BP2', BP3') is designed on each island section (IA) with spring segments (FS1, FS2) arranged asymmetrically around the respective attachment point (BP2; BP2', BP3'). Osteosynthesis plate (OP; OP'; OP''; OP''') according to at least one of the preceding claims, characterized in that a second of the spring segments (FS1, FS2) is oriented at an acute angle to a direction which is oriented orthogonally to a longitudinal direction of the fastening section (BA2; BA2', BA3'). Osteosynthesis plate (OP''; OP'''') according to claims 6 and 7, characterized in that the several attachment points (BP2; BP2', BP3') formed on island sections (IA) are formed successively in the longitudinal direction of the respective attachment section (BA2; BA2', BA3'), wherein adjacent island sections (IA) are formed identically to each other and are arranged in a point-mirror manner, in that the adjacent island sections (IA) are oriented towards each other with the acute-angled spring segments (FS2). Osteosynthesis plate (OP; OP'; OP''; OP''') according to at least one of the preceding claims, characterized in that the fastening sections (BA1, BA2; BA1', BA2', BA3') are arranged in pairs on both sides of an intermediate bridge section (BU; BU1, BU2) which is provided to bridge a gap (S) running between the bone fragments (K1, K2). Osteosynthesis plate (OP; OP') according to claim 9, characterized in that at least one of the asymmetrically arranged spring segments (FS1, FS2) is aligned such that, when subjected to a load (B) in a main load direction of the bone (K), a relative displacement takes place between the respective island section (IA) and the respective attachment section (BA2; BA2'), in which the distance of the respective island section (IA) to the bridge section (BU; BU1) increases. Osteosynthesis plate (OP; OP'; OP''; OP''') according to at least one of the preceding claims, characterized in that in one of the fastening sections (BA1, BA2; BA1', BA2', BA3') the at least one fastening point (BP1; BP1') is designed to be fixed in position. Osteosynthesis plate (OP'; OP'') according to at least one of the preceding claims, characterized in that the attachment points (BP2', BP3') are designed on island sections (IA) in several or all attachment sections (BA2', BA3').

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