Bone Fixation Device

Abstract

A bone fixation device (1) is presented comprising a wire (7) and a load distributor (9), the load distributor comprising a contact side (2) having a contact area (11) that presses against the bone to be fixed upon tightening of the wire (7) and two opposing lateral sides (4) that do not contact the bone upon tightening of the wire (7). At least one of the lateral sides (4) is provided with a number of recesses (5) that do not extend into the contact side (2). The contact side (2) of the load distributor (9) has a continuous smooth surface that is configured to slide across the bone without damaging the bone when the load distributor (9) is pulled longitudinally across the bone during application.

Description

[Technical field]

[0001] FIELD OF THEINVENTION The present invention relates generally to surgical devices, and more specifically to bone fixation devices and load distributors for bone fixation devices. [Background technology]

[0002] Fragmented or severed bones often require the application of bone fixation devices, which involve flexible straps or wires that are looped around the bone segments and tightened like a cable tie.

[0003] During cardiac surgery, the sternum must often be cut longitudinally to gain access to the heart. Once the operation is complete, the two sternum bones are rejoined. This is usually done using a simple wire or a more advanced sternum closure device with a wire and load distributor as disclosed in EP 3378424 A1. During application, the known instrument is passed under the bone and looped around it. Finally, the free end of the wire is twisted to tighten the device, exerting an external force pressing the bone segments together.

[0004] The sternum closure device disclosed in EP 3378424 A1 has a load distributor molded around the wires to avoid cutting the bone when tightening the wires around the bone. However, the load distributor is composed of multiple segments separated from each other by recesses. Because the individual segments are spaced apart and the segments have edges on the bone-contacting side, the load distributor can injure the periosteum when the load distributor is pulled longitudinally across the bone surface during application.

[0005] US 2020 / 297402 A1 discloses a bone fixation device (2) comprising a wire (12) and a load distributor surrounding the wire, the device having a channel extending longitudinally therethrough, one contact side having a contact area configured to be pressed against the bone to be fixed when the wire is tightened, and two opposing lateral sides not in contact with the bone when the wire is tightened, the lateral sides having a plurality of recesses. US 2021 / 307799 A1 teaches a bone fixation device consisting of a load distributor surrounding the wire and having a smooth contact surface. Other bone fixation devices with load distributors are disclosed in US 2011 / 054545 A21 and US 5 993 452 A. Summary of the Invention

[0006] The object of the present invention is to provide a bone anchoring device which, when applied, is less damaging to the bone, and in particular to the periosteum.

[0007] According to one aspect of the present invention, a bone fixation device is provided, which comprises a load distributor and a wire and a load distributor. The load distributor comprises one or two contact sides having a contact area that is pressed against the bone to be fixed when the wire is tightened. The bone fixation device further comprises two opposing lateral sides that are not in contact with the bone when the wire is tightened.

[0008] According to one embodiment of the invention, one or both contact regions have a smooth contact surface configured to slide across the bone without damaging the bone when the load distributor is pulled longitudinally across the bone during application. In some embodiments, as a result of injection molding of the load distributor, there may be one or more injection points at the contact surface. However, these injection points do not extend across the entire width of the load distributor and have soft contours so as not to cause trauma to the periosteum.

[0009] When viewed from above or below, the load distributor is preferably formed as a strip with parallel straight side edges. In an embodiment, the load distributor has a constant width at least in its central portion, particularly in the contact area.

[0010] When used as a sternum closure, the contact area, i.e., the portion of the load distributor that rests on the bone after the device is applied to the bone, can have a length of 50mm to 70mm, but can be shorter or longer depending on the size of the bone being fixed. The overall length of the load distributor can be, for example, 60mm to 80mm.

[0011] One of the lateral sides of the load distributor may be provided with one or more recesses that weaken the material of the load distributor to increase flexibility and allow for easy separation of excess material of the load distributor. Thus, the surgeon may shorten the length of the load distributor as needed by simply cutting or twisting off the protruding end. In a preferred embodiment, the recess(es) are located exclusively on one or both sides of the load distributor without contacting or extending to the contact side, respectively.

[0012] If the load distributor material is sufficiently soft and flexible, embodiments without lateral recesses are possible.

[0013] In the context of this disclosure, the term "wire" refers to any elongated element such as: B. thread, strap, ribbon, etc., and should not be understood as being limited to metal wire.

[0014] In some embodiments, the load distributor comprises a fastening for securely fastening the wire, in particular by friction, so that the wire cannot be removed under normal operating conditions. According to one embodiment of the invention, the wire has one or more bends in the area of ​​the load distributor that create sufficient friction to securely fasten the wire in the load distributor. The bends can be provided by pushing or bending the wire. The preformed wire is overmolded by the load distributor.

[0015] According to a special embodiment, the wire has an undulating course in the load distributor. In this context, the term "undulating course" relates to a wave-like or zigzag course. If the wire creates sufficient friction in the load distributor, no additional gluing is necessary. In other embodiments, the wire may be glued to the load distributor.

[0016] In a preferred embodiment of the load distributor, the contact side does not have any recesses or depressions in its contact area that may injure the periosteum during application of the device.

[0017] In some embodiments, the continuous smooth surface of the contact side extends essentially along the entire length of the load distributor from the front end to the rear end of the load distributor.

[0018] In some embodiments, the load distributor has a slit running its entire length that allows the wire to be assembled after the load distributor is manufactured. In embodiments, also called "top loader", the slit is located on the top side of the load distributor, i.e., opposite the contact side. In embodiments, also called "side loader", the slit is located on one of the sides of the load distributor. The width of the slit is designed to be slightly smaller than the diameter of the wire, so that the wire must be pushed through the slit into the internal channel. Once inserted, the wire is held in the channel and cannot easily be pulled out due to the small gap width.

[0019] The recess provided in at least one of the lateral sides of the load distributor can be configured as a through hole, a blind hole, or generally as a hole or aperture.

[0020] The recess may be located outside the contact area in the region of the free end of the load distributor, or one or more recesses may be located within the contact area to increase the flexibility of the load distributor.

[0021] In a special embodiment of the load distributor, at least one of the lateral sides is provided with a number of recesses, some of which may be located inside the contact area and other recesses may be located outside the contact area.

[0022] With regard to manufacturing the bone fixation device, the load distributor can be molded around the wire in a molding process such as injection molding. Alternatively, the load distributor can be manufactured by 3D printing or other known techniques. The load distributor may be made from a moldable material, such as a polymeric material.

[0023] In some embodiments, the load distributor may be integrally formed. In other embodiments, the load distributor may comprise multiple pieces that are joined together after the wires are inserted into the channels. The various pieces of the load distributor may be joined by, for example, ultrasonic welding or adhesive bonding or other known techniques.

[0024] In some embodiments, the load distributor is configured axisymmetrically about the central longitudinal axis.

[0025] The load distributor may include two contact sides located on two opposite sides thereof. The contact sides may be essentially identical. This makes it easier for the surgeon to use the device since the bone fixation device can be used in both orientations (normal or top-down) and does not need to pay attention to the orientation of the device.

[0026] The tapered free end of the load distributor facilitates annular fixation of the load distributor to the bone and reduces trauma to the bone.

[0027] In embodiments, the tapered end may have one or more edges that act as blades to facilitate insertion of the device. The end may extend substantially in a longitudinal direction. It may be curved and / or angled relative to the longitudinal direction.

[0028] According to one embodiment of the invention, one or both of the contact sides may have a convex shape. [Brief description of the drawings]

[0029] Further details, advantages and aspects of the present invention will become apparent from the following embodiments taken in conjunction with the drawings. [Figure 1a] FIG. 2 is a perspective top view of a load distributor of the bone fixation device according to the first embodiment. [Figure 1b] 1b shows a cross-sectional view of the load distributor of FIG. 1a taken along a central horizontal plane. [Figure 1c] 1 shows a cross section along a central vertical plane of the load distributor of FIG. 1a. [Figure 1d] FIG. 1b is a cross-sectional view of the load distributor of FIG. 1c along line AA. [Figure 1e] FIG. 1 is a perspective view of a bone anchoring device according to a first embodiment. [Figure 2a] FIG. 13 is a perspective top view of a load distributor of a bone fixation device according to a second embodiment. [Figure 2b] 1 shows a longitudinal view of a load distributor according to a second embodiment. [Figure 2c] FIG. 11 is a cross-sectional view of a load distributor according to a second embodiment. [Figure 3a] FIG. 13 is a top perspective view of a load distributor according to a third embodiment of the present invention, also referred to as a "side loader." [Figure 3b] 1 shows a load distributor according to a third embodiment in a longitudinal view. [Figure 3c] FIG. 11 is a cross-sectional view of a load distributor according to a third embodiment. [Figure 3d] FIG. 11 is a cross-sectional view of a load distributor according to a third embodiment. [Figure 4a] FIG. 13 shows a top perspective view of a load distributor according to a fourth embodiment of the invention comprising two halves. [Figure 4b] FIG. 11 is a diagram showing the load distributor according to the fourth embodiment as viewed in the longitudinal direction. [Figure 4c] FIG. 10 is a cross-sectional view of a load distributor according to a fourth embodiment. [Diagram 5] FIG. 13 is a top view of a load distributor according to a fifth embodiment, showing the two halves of the load distributor prior to wire assembly. [Figure 6a] FIG. 13 is a side view of the wires and hooks used in the load distributor. [Figure 6b] FIG. 6b is a top view of the wire and hook assembly of FIG. 6a. [Figure 7a] 1A-1D show various views of an embodiment of a bone fixation device having a cutting tool at its end. [Figure 7b] 1A-1D show various views of an embodiment of a bone fixation device having a cutting tool at its end. [Figure 7c] 1A-1D show various views of an embodiment of a bone fixation device having a cutting tool at its end. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] In the following, the same reference numbers are used to denote the same or similar structural features.

[0031] Figures 1a to 1e show different views of a bone anchoring device 1 according to a first embodiment, which can be used as a sternum obturator, for example in cardiac surgery, but the device 1 can also be used in other applications where parts of a bone have to be fixed by an external force.

[0032] The bone fixation device 1 shown in Fig. 1a-e is essentially used to fix a portion of a bone by means of an external force. Fig. 1a-e essentially consists of a wire 7 and a load distributor 9 arranged around the wire 7. During application, the wire 7 is threaded under the bone by means of a curved needle 8. The surgeon then pulls the wire 7 until the load distributor 9 is in the correct position, bringing the free end of the wire 7 together proximally of the bone. Finally, the bone fixation device 1 is tightened by simply twisting the free end, which exerts an external force on the bone segment, pressing it tightly. The load distributor 9 prevents the wire 7 from cutting into the bone, since the force exerted by the wire 7 is distributed over a larger area.

[0033] In the embodiment of Fig. 1a-e, the wire 7 is a metal wire and the load distributor 9 is made of plastic. The load distributor 9 comprises a channel 10 extending therein in a longitudinal direction L. The load distributor 9 further comprises two contact surfaces 2, one at its top and one at its bottom, one of which is pressed against the bone surface upon tightening of the wire 7. The area of ​​the contact surface 2 which is in contact with the bone after tightening of the device 1 is called the "contact area" 11 (see Fig. 1a). As can be easily understood, the length of the contact area 11 depends on the size of the bone. To shorten the length of the load distributor 9 if necessary, the excess material of the load distributor 9 protruding beyond the contact area 11 can simply be cut or threaded off. For this purpose, each of the lateral sides 4 of the load distributor 9 comprises a number of recesses 5 in the form of holes or bores which weaken the material and facilitate cutting off or twisting the ends of the load distributor 9.

[0034] As shown in Figure 1a, the contact sides 2 each have a continuous smooth surface that prevents damage to the bone, specifically the periosteum, when the load distributor 9 is pulled longitudinally across the bone during application. Figure 1a also shows that the contact sides 2 have no recesses or depressions within the contact area 11 (apart from possible injection points resulting from injection molding). Additionally, the load distributor 9 has a tapered end 3 that further contributes to a bone-friendly application.

[0035] The load distributor 9 of the first embodiment is configured axially symmetrically with respect to the central longitudinal access A.

[0036] FIG. 1b shows the internal structure of the load distributor 9, a cross-sectional view taken along a horizontal central plane. As can be seen, the load distributor 9 is provided with a fastening 6 for securely fastening the wire 7. For this purpose, the wire 7 has one or more curved portions which create sufficient friction to securely fasten the wire inside the load distributor 9. The undulating portions of the wire 7 may, for example, be wavy or zigzag, as shown.

[0037] In the embodiment of Figures 1a-1e, the load distributor is integrally moulded around the wire 7 in an injection moulding process.

[0038] Figures 2 to 2c show different views of a load distributor 9 according to a second embodiment, also called "top loader". In this embodiment, the load distributor 9 is manufactured in a first step, for example by injection molding, after which the wire 7 is assembled through the top surface of the load distributor 9. For this, the load distributor 9 is provided with a slit 12 which extends along its entire length and communicates with an internal channel 10. The width of the slit 12 is smaller than the diameter of the wire 7, so that the wire 7 has to be pushed into the channel 10 from the outside. Due to the small width of the slit 12, the wire 7 is kept in the channel 10 after assembly.

[0039] Figure 2b shows a load distributor 9 according to the second embodiment as seen in the longitudinal direction L, and Figure 2c shows a cross-sectional view of the load distributor 9. As can be seen from Figure 2c, the recesses 5 are provided in both lateral sides 4 of the load distributor 9 in the form of blind holes.

[0040] Figures 3a-c show various views of a load distributor 9 according to a third embodiment, also called a "side loader". The load distributor 9 comprises a slit 12 which extends over the entire length of the load distributor 9 and is provided on one lateral side 4 of the load distributor 9. The other lateral side 4 is provided with a number of recesses 5.

[0041] FIG. 3b is a view of the load distributor 9 according to the third embodiment as viewed in the longitudinal direction L, and FIG.

[0042] Figures 4a-c show various views of a load distributor 9 according to a fourth embodiment. In this embodiment, each lateral side 4 is provided with a number of through holes communicating with the internal channel 10. The through holes are arranged side by side, thereby leaving ribs 14 between them. The ribs 14 arranged on one side 4 of the channel 10 are offset from the ribs 14 arranged on the other side of the channel 10. This creates a kind of stitch pattern as shown in Figure 4a.

[0043] In the fourth embodiment of Fig. 4a-c, the load distributor 9 is made of two halves 9a, 9b that are manufactured separately and connected to each other after the wire 7 is inserted into the channel 10. As shown, the channel 10 has curved or undulating parts to ensure that the wire 7 is fixed to the load distributor 9 by friction. Fig. 4b shows the load distributor 9 when viewed in the longitudinal direction L with the two halves 9a, 9b assembled. Fig. 4c is a cross-sectional view of the load distributor 9 according to the fourth embodiment.

[0044] The load distributor 9 shown in Figure 5 is an assembly of two halves 9a, 9b which are connected to each other by ultrasonic welding after the wire 7 is inserted into the channel 10. The load distributor 9 has contact surfaces 2 on its upper and lower sides. The side surface 4 is provided with a number of recesses 5. The end 3 of the load distributor 9 is tapered.

[0045] Figure 6a shows the assembly of wire 7 and needle 8 in a side view. Figure 6b shows a top view of the assembly of Figure 6a. As can be seen in Figure 6b, the wire 7 has an undulating portion 13 created by bending and pushing the wire 7 in this area. The undulating portion of the wire 7 engages the fixed portion 6 of the load distributor 9, thereby preventing the wire 7 from becoming dislodged.

[0046] 7a-7c show an embodiment of a bone fixation device 1 having a cutting tool at its end 3 to facilitate insertion and ejection of the device. In this embodiment, the cutting tool consists of an edge 16 or blade formed on the tapered end 3 of the load distributor, respectively. The edge 16 is slightly curved but extends substantially along the length of the device 1.

[0047] The load distributor 9 as shown in Figure 7a shows some injection points 15 on the contact surface 2 as a result of injection moulding. However, these injection points 15 are only for technical reasons: they do not damage the bone when the device 1 is pulled under the bone.

Claims

1. A bone anchoring device (1), comprising: A wire (7) and a load distributor (9) surrounding the wire (7), - a channel (10) extending therethrough in a longitudinal direction (L) adapted to receive said wire (7) therein; a contact surface (2) having a contact area (11) adapted to be pressed against the bone to be fixed when the wire (7) is tightened; - two opposing lateral sides (4) that are not in contact with the bone when the wire (7) is tightened, at least one of the lateral sides (4) comprising one or more recesses (5) that do not extend to the contact side (2); A load distributor (9) comprising: Bone fixation devices.

2. 2. The bone fixation device (1) according to claim 1, wherein at least one of the contact sides (2) has a smooth surface, at least in its contact area (11), configured to slide across the bone without damaging the bone when the load distributor (9) is pulled longitudinally across the bone during application.

3. The bone anchoring device (1) according to claim 1, wherein the contact side (2) has no recesses or depressions, at least in the contact area (11).

4. 2. The bone anchoring device (1) according to claim 1, wherein the contact side (2) has an essentially continuous smooth surface over the entire length of the load distributor (9).

5. The bone anchoring device (1) according to claim 1, wherein the wire (7) has one or more bends which serve to fix the wire (7) in the load distributor (9) by friction.

6. 2. The bone fixation device (1) according to claim 1, wherein the load distributor (9) has a slit (12) extending along its entire length configured to allow assembly of the wire (7) after manufacture of the load distributor (9).

7. 2. The bone anchoring device (1) according to claim 1, wherein the recess (5) in at least one of the lateral sides (4) is configured as a through hole or a blind hole.

8. The bone anchoring device (1) according to claim 1, wherein the recess (5) is located outside the contact area (11).

9. 2. The bone anchoring device (1) according to claim 1, wherein both lateral sides (4) are provided with a number of recesses (5).

10. The bone anchoring device (1) according to claim 1, wherein the load distributor (9) is molded around the wire (7) or manufactured by 3D printing.

11. The bone anchoring device (1) according to claim 1, wherein the load distributor (9) comprises a number of parts (9a, 9b) which are connected to each other after the wire (7) is inserted into the channel (10).

12. 2. The bone anchoring device (1) according to claim 1, wherein the load distributor (9) is configured axially symmetrically with respect to a central longitudinal axis (A).

13. The bone anchoring device (1) according to claim 1, wherein the load distributor (9) has one or two tapered ends (3).

14. A load distributor (9) for a bone anchoring device (1), comprising: - a longitudinally extending channel (10) adapted to receive a wire (7) therein; a contact surface (2) having a contact area (11) that is pressed against the bone to which it is fixed when the wire (7) is tightened; - two opposing lateral sides (4) that are not in contact with the bone when the wire (7) is tightened, at least one of the lateral sides (4) being provided with a number of recesses (5) that do not extend to the contact side (2); A bone fixation device comprising:

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