Bone Plate Mounting Assembly

Abstract

A bone plate mounting assembly having a plate holder (10) made of an elastic polymer, a bone plate (20), and a bone screw (41), wherein the plate holder (10) has a compressible face center retention protrusion (13) positioned within a plate receiving recess (14), and the bone plate (20) has a body center retention opening (21), whereby the bone plate (20) is temporarily retained in the plate holder (10) by inserting the face center retention protrusion (13) into the body center retention opening (21).

Description

[Technical field]

[0001] The present invention generally relates to the field of systems and assemblies for mounting bone plates of the type used to connect adjacent bone portions or to cover openings in bone, which include a handheld screw guide device configured to temporarily hold one or more screws or similar mechanical fasteners in a fixed position and orientation that coincides with a screw-receiving opening of a plate or similar member to be secured to the bone, and the screws are driven from the screw-retaining guide through the screw-receiving opening of the plate into the bone to securely attach the plate to the bone. The screw-retaining device is often referred to as a screw guide, caddy or magazine. More specifically, the present invention relates to such a system or assembly in which the screw-retaining guide further functions as a bone plate holder that temporarily holds the bone plate in the assembly unit, and more specifically, the body of the screw-retaining guide and holder is made of a flexible, compressible, resilient material. [Background technology]

[0002] In the medical field, it is often necessary to use mechanical fasteners, i.e. bone screws, to fasten a substantially rigid, malleable, or slightly flexible bone plate to a bone or separate bone portions, such as, for example, a sternum plate fastened to a longitudinally split sternum half or a skull plate positioned across an opening in the skull. The bone plate has a number of threaded or non-threaded screw-receiving openings through which the bone screws are driven into the underlying bone. To speed up the process of fastening the bone plate and ensure that the bone screws are driven into the bone at the proper angles, it is known to provide a handheld screw-holding guide device having holes that are positioned in accordance with the positions of the screw-receiving openings in the bone plate. The bone screws are temporarily positioned, i.e. pre-loaded, in the holes provided in the screw guide. The screw guide is then aligned with or temporarily attached to the bone plate, thereby properly positioning all of the bone screws in their respective screw-receiving openings. Once the bone plate is properly positioned on the bone, the screws are driven from the screw guide, through the bone plate, and into the underlying bone. In an improved design, the screw guide also serves as a temporary holder for the bone plate, allowing the surgeon to place the bone plate in the desired location on the bone by holding the combination screw guide and plate holder.

[0003] Temporary retention of the bone plate in the screw guide and plate holder combination can be achieved in a variety of ways, including clips, friction or compression fits, mechanical interlocks, or by providing the screw guide with a recess for receiving the bone plate. US Pat. No. 5,399,433 discloses an assembly in which a cylindrical guide / holder made of elastic material has a number of circumferentially spaced screw receiving holes that are aligned with the screw receiving openings of a disk-shaped bone plate. The bone plate is temporarily held by a ring of compressible elastic projections that are pressed into correspondingly spaced and sized mounting openings in the bone plate. US Pat. No. 5,399,433 describes another such assembly in which the bone plate is temporarily held in the elastic screw guide / holder by, for example, providing a recess on the mating side of the guide / holder that matches the shape of the bone plate but is slightly smaller, thereby forcing and holding the bone plate in the recess. A problem faced with these devices is that in many situations the surgeon needs to bend the bone plate before fixation to better fit the surface shape or geometry of the bone. Because the bone plate is held to the mating surface of the guide / holder by physical structures (protrusions, recess walls) near or at the edges of the bone plate, bending the bone plate often prevents the screw guide and plate holder combination from holding the bone plate.

[0004] To address this issue, more complex structural designs of screw guide and plate holder combinations have been proposed, such as those shown in U.S. Pat. Nos. 5,993,333, 5,103,222 and 5,292,633. The proposed solutions typically utilize clips or other mechanical connections to couple the bone plate to the screw guide and plate holder combination, resulting in cumbersome devices that require complex manufacturing. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 7,588,576 [Patent Document 2] U.S. Pat. No. 9,572,611 [Patent Document 3] U.S. Patent No. 10,226,290 [Patent Document 4] U.S. Pat. No. 11,033,284 [Patent Document 5] US Patent Application Publication No. 2021 / 0267650 Summary of the Invention [Means for solving the problem]

[0006] It is an object of the present invention to provide an improved flexible screw guide and bone plate holder fixation system or assembly over known systems by providing the screw guide and plate holder combination as one uniform body of flexible, resilient, compressible material without additional internal or external structural support members. The screw guide and plate holder combination is provided in combination with a bone plate that is temporarily coupled to or temporarily held by the screw guide and plate holder combination. The screw guide and plate holder combination includes a centrally located body central retaining protrusion that temporarily fits into a centrally located body attachment opening disposed on the bone plate. The centrally located body central position allows the bone plate to remain coupled to the screw guide and plate holder combination even if the peripheral edges or extension arms of the bone plate are bent as necessary to properly fit the bone surface. Such a screw guide and plate holder combination is easy to handle by the surgeon, reduces manufacturing costs, and does not require assembly of components.

[0007] The present invention is, in summary, a bone plate attachment system or assembly including a combination of a flexible screw guide and bone plate holder made uniformly of an elastic polymer or copolymer, a bone plate constructed and configured for fastening to a bone, and a bone screw, the flexible screw guide and bone plate holder having a hole for receiving and temporarily retaining a bone screw, the screw retaining hole passing completely through the body of the flexible screw guide and bone plate holder into a plate receiving recess located on a distal face, and a central face center retaining protrusion located within the plate receiving recess.

[0008] The bone plate is a thin, structurally rigid member with a screw receiving opening and a central body central retaining opening. The shape of the peripheral edge of the bone plate corresponds to the shape of the plate receiving recess, and preferably the overall lateral dimension of the bone plate around the peripheral edge is slightly larger than the overall lateral dimension of the plate receiving recess. Preferably, the shape of the central face retaining protrusion of the flexible screw guide and bone plate holder corresponds to the shape of the central body central retaining opening of the bone plate, and the lateral dimension of the central face retaining protrusion is slightly larger than the lateral dimension of the central body central retaining opening. However, the shape of the central face retaining protrusion may differ from the shape of the central body retaining opening, if there is a sufficient portion of it. In this form, the bone plate is temporarily attached or coupled to the flexible screw guide and bone plate holder by forcing the bone plate into the plate receiving recess, such that the central body retaining opening is held in compression by the central face retaining protrusion, and preferably the peripheral edge of the bone plate is held in compression by the elasticity of the wall of the recess.

[0009] The matching shapes of the plate-receiving recesses and the bone plate ensure proper alignment between the screw-retaining holes of the flexible screw guide and bone plate holder and the screw-receiving openings of the bone plate, so that with the bone plate properly positioned on the bone, bone screws can be driven through the screw-retaining holes and screw-receiving openings into the bone. With the bone plate secured to the bone, the flexible screw guide and bone plate holder are easily removed from the bone plate.

[0010] A significant advantage of the assembly of the present invention described over prior art devices is the provision of a central face central retaining protrusion and a central body central retaining opening as the primary means for temporarily retaining the bone plate to the flexible screw guide and bone plate holder. In many situations, the bone plate needs to be adjusted by the surgeon to better fit the bone surface, which is accomplished by removing the bone plate from the assembly and bending some or all of the outer or extended portions of the bone plate. In prior art systems, bending the bone plate renders the guide / holder unusable or less effective, since the bent portions of the bone plate are no longer able to connect or mate with the retaining means of the guide / holder. This problem is overcome by securing the bone plate to the flexible screw guide and bone plate holder primarily at or near the center, rather than at or near the periphery, since reshaping the outer portions of the bone plate does not adversely affect the center. [Brief description of the drawings]

[0011] [Figure 1] 1 shows an exploded perspective view of an embodiment of the present invention in which the bone plate is generally X-shaped. [Diagram 2] 13 is an exploded perspective view of another embodiment of the present invention in which the flexible screw guide and bone plate holder are configured in a shape similar to that of an X-shaped bone plate. FIG. [Diagram 3] FIG. 3 is a distal view of the embodiment of FIG. 2. [Figure 4]4 is a partial cross-sectional side view of the embodiment of FIG. 2 taken along line 4-4, showing the screw-retaining holes of the flexible screw guide and bone plate holder and the screw-receiving openings of the bone plate. [Diagram 5] 13 is an exploded perspective view of another alternative embodiment of the present invention in which the flexible screw guide and bone plate holder are configured in a shape similar to that of a generally oval bone plate; FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present invention will now be described in detail with reference to the drawings, which are intended to be representative and illustrative, not limiting in scope. The term "flexible" is used herein to encompass materials that are compressible and have elasticity to return to their original shape when compression is removed. For better readability, the term "plate holder" is used herein as an abbreviation for the expanded term "flexible screw guide and bone plate holder", so that the former and latter uses are equivalent. The term "distal" is used herein to refer to the direction toward the bone when the assembly is placed on the bone in use, such that the side that holds the bone plate when assembled is the distal surface of the plate holder. The term "lateral" is used herein to refer to a lateral direction generally perpendicular to the distal direction.

[0013] A basic embodiment of the assembly or system described herein is shown in Figure 1, and a more ergonomic shape of the plate holder 10 is shown in Figure 2. The invention is generally an assembly, system or combination of a plate holder 10, a bone plate 20 and a bone screw 41. The bone plate 20 is temporarily attached to or held by the plate holder 10 by compressible or biased elastomeric forces, such that the bone plate 20 is held to the plate holder 10 during movement and placement, but once the bone plate 20 is secured to the bone, the plate holder 10 is easily removed from the bone plate 20 by manual force.

[0014] Bone plates 20 are well known in the art. Such implants are used to join broken or separated bone portions, such as a severed sternum, in a relatively rigid, fixed relationship to allow healing and mechanical support, and to cover gaps or holes in bone, such as foramen in the skull. The bone plate 20 includes screw-receiving openings 22 through which bone screws 41 can pass into the bone to secure the bone plate 20 to the bone. The bone plate 20 is made of a biocompatible material with suitable strength characteristics, such as titanium, ceramic, or the like. The bone plate 20 is typically thin in thickness, with a peripheral edge 23 defining the configuration or shape of the bone plate 20. A typical bone plate 20 can be substantially or approximately rectangular, circular, oval (FIG. 5) or X-shaped (FIGS. 1-3), and such shape can define an extension portion 24 that can include an extended body portion or arm. The bone plate 20 may be malleable so that the extension portion 24, or the entire bone plate 20, may be bent before being secured to the bone to more closely approximate or conform to the surface shape of the bone.

[0015] The bone plate 20 of the present invention has a centrally located central retaining opening 21 that is significantly larger than the screw receiving openings 22. The shape of the central retaining opening 21 can vary, but a non-circular central retaining opening 21 is preferred to better ensure proper alignment and orientation of the bone plate 20 in the plate holder 10. For symmetrical bone plates 20 with an exact center, the center of the central retaining opening 21 is preferably coincident with the exact center. For other bone plate 20 shapes, the proper central location is determined such that bending or bone plate extensions 24 do not adversely affect retention of the bone plate 20 by the plate holder 10.

[0016] Plate holder 10 is a homogenous body of a resilient polymer or copolymer, such as silicone, that allows plate holder 10 to be flexible, compressible, and retain a neutral shape when the compressive or biasing force is removed. The polymer should be approved for use in patient contact and implantation, and preferably has a Shore A hardness of about 40-100, and a Shore D hardness of about 10-90. Most preferably, the Shore A hardness is about 70-90. No internal or external reinforcing or strengthening members or elements are required.

[0017] The overall configuration or shape of the plate holder 10 may vary. In a basic embodiment, the plate holder may be block-shaped (FIG. 1), but preferably the shape of the plate holder 10 more closely resembles the shape of the bone plate 20 (FIGS. 2, 3, 5) so that the position of the bone plate 20 is better visible to the surgeon during insertion and fixation into the bone. The matching shapes of the bone plate 20 and the plate holder 10 may also provide a more ergonomic or comfortable grip for the surgeon. The plate holder 10 may include orientation markings 16 or other indicia.

[0018] The plate holder 10 includes screw retaining holes 11 configured to temporarily retain bone screws 41. The number and location of the screw retaining holes 11 correspond to the number and location of the screw receiving openings 22 of the bone plate 20. The screw retaining holes 11 extend completely through the plate holder 10 and open into a plate receiving recess 14 located on the distal surface 12 of the plate holder 10. The screw retaining holes 11 may have a simple tubular structure, but preferably include a screw retaining structure 30, such as an annular or longitudinal rib, that retains and properly orients the bone screws 41 while allowing the bone screws 41 to be easily driven from the screw retaining holes 11 through the screw receiving openings 22 of the attached bone plate 20 and into the bone. A preferred configuration is shown in FIG. 4, where the screw retaining holes 11 include a wavy screw retaining structure 30, a narrowed alignment neck 31, and a flared distal opening 32. The screw retaining hole 11 on the right side is shown retaining a relatively short bone screw 41, while the screw retaining hole 11 on the left side retains a significantly longer bone screw 41. The flared distal opening 32, in combination with the inherent flexibility of the plate holder 10 when the extension portion 24 is bent to better conform to the bone surface, allows the bone screw 41 to be inserted into the bone plate 20 at an angle up to about 20 degrees from vertical.

[0019] The plate holder 10 includes a plate-receiving recess 14 disposed on a distal surface 12 of the plate holder 10. The plate-receiving recess 14 has recess walls 15 and is configured to correspond or match the shape of the bone plate 20. That is, the configuration or shape of the recess walls 15 of the plate-receiving recess 14 corresponds or matches the configuration or shape of the peripheral edge 23 of the bone plate 20. This ensures that the screw-retaining holes 11 of the plate holder 10 are properly aligned with the screw-receiving openings of the bone plate 20 when the bone plate 20 is mated to the plate holder 10. Most preferably, the lateral dimensions of the plate-receiving recess 14 are slightly less than the lateral dimensions of the peripheral edge 23 of the bone plate 20 such that insertion of the bone plate 20 into the plate-receiving recess 14 biases or compresses the recess walls 15 outwardly, thereby providing temporary retention of the bone plate 20 by the plate holder 10. To ensure proper initial contact between the bone plate 20 and the bone upon installation, the depth of the plate-receiving recess 14 is most preferably equal to or less than the thickness of the bone plate 20.

[0020] The plate holder 10 also includes a central compressible face center retaining protrusion 13 located within the plate receiving recess 14. The face center retaining protrusion 13 is arranged and configured to correspond to the location and configuration of the body center retaining opening 21 of the bone plate 20 when the bone plate 20 is attached to the plate holder 10. The lateral dimension of the face center retaining protrusion 13 is slightly larger than the lateral dimension of the body center retaining opening 21, such that insertion of the bone plate 20 into the plate receiving recess 14 of the plate holder 10 biases or compresses the face center retaining protrusion 13 inwardly, thereby providing temporary retention of the bone plate 20 by the plate holder 10. Preferably, the overall peripheral shape of the face center retaining protrusion 13 generally corresponds or matches the overall shape of the body center retaining opening 22 of the bone plate 20. However, the shape of the face center retaining protrusion 13 may differ from the shape of the face center retaining opening 22, provided that a sufficient portion of the face center retaining protrusion 13 is present in the plate holder 10 to be compressed to retain the bone plate 20. For example, the body center retention opening 22 of the bone plate 20 can be rectangular, while the face center retention protrusion 13 can be formed as a cross with slightly larger dimensions. The face center retention protrusion 13 and other portions of the plate holder 10 may include one or more internal holes or passages to reduce the amount of material and / or increase flexibility.

[0021] In use, bone screws 41 are inserted into the screw retaining holes 11 of the plate holder 10, the bone plate 20 is attached to the plate receiving recess 14 of the plate holder 10, and the central retaining openings 21 of the bone plate 20 compress or bias the resilient central retaining projections 13 located in the plate receiving recess 14, thereby temporarily retaining the bone plate 20 by the plate holder 10. This combination defines a bone plate mounting assembly. The surgeon then grasps the -+ plate holder 10 and places the bone plate 20 in the desired location on the bone. The bone screws 41 are then driven through the screw retaining holes 11 and through the screw receiving openings 22 of the bone plate 20 into the bone. Once the bone plate 20 is secured to the bone, the surgeon pulls the plate holder 10 away from the bone plate 20.

[0022] If the bone plate 20 needs to be bent or otherwise adjusted to better fit the bone surface shape, the bone plate 20 is removed from the plate holder 10 and the surgeon adjusts the bone plate 20 by bending, angling or reshaping the extensions 24 of the bone plate 20 such that one or all of the extensions 24 no longer match or fit within the plate receiving recesses 14. Due to the structure of the plate holder 10 and bone plate 20, specifically the presence of the face center retaining protrusions 13 and the body center retaining openings 22, the bone plate 20 can be reattached to the plate holder 10 solely by a compressed or biased fit between the face center retaining protrusions 13 and the body center retaining openings 22. The fixation procedure is then performed as described.

[0023] Depending on the flexibility, resilience and thickness of the plate holder 10, the shape of the bone plate 20 and the plate holder 10, the location of the screw receiving openings 22, the size and dimensions of the extensions 24, the length of the bone screws 41, and other variables, bending the bone plate extensions more than about 20 degrees out of plane will likely result in the angle between the axis of the screw retaining holes 11 and the axis of the screw receiving openings 22 of the bone plate 20 becoming too large to allow the screw retaining holes 11 in the outermost or most bent portion to be used to secure the bone plate 20 to the bone. In such a case, the adjusted bone plate 20 is reattached to the plate holder 10 utilizing the combination of the face center retention protrusions 13 and the body center retention openings 22. The bone plate 20 is then properly positioned and secured to the bone using bone screws 41 retained in at least one of the remaining functional screw retaining holes 11 in alignment with at least one screw receiving opening 22, i.e., in the innermost or most planar area relative to the bone plate 20. The plate holder 10 is then separated from the bone plate 10 and the bone screws 41 are inserted directly into the remaining screw receiving openings 22 and driven into the bone.

[0024] Alternatively, the screw receiving holes 11 may be used as drill guides to drill pilot holes in the bone for the bone screws 41. With the bone screws 41 removed from the plate holder 10 and the bone plate 20 attached to the plate holder 10 properly positioned relative to the bone, the surgeon inserts a drill bit into the empty screw receiving opening 11 and drills a pilot hole. The bone screws 41 are then inserted or reinserted into the screw receiving holes 11 and the fixation procedure is performed as described.

[0025] Equivalents and alternatives to the specific elements and structures described above are contemplated and may be apparent to those of ordinary skill in the art, therefore, the true scope and definition of the invention is as set forth in the following claims. [Explanation of symbols]

[0026] 10 Plate holder 11 Screw retaining hole 13 Center holding protrusion 14 Plate receiving recess 15 Recessed wall 16 Orientation Label 20 Bone Plate 21 Center holding opening 22 Screw receiving opening 23 Periphery 24 Extension 30 Screw retention structure 41 Bone Screw

Claims

1. 1. A bone plate mounting assembly comprising: a bone plate (20) having a central retaining opening (21), a screw receiving opening (22), a peripheral portion (23) and an extension portion (24); A bone screw (41); A plate holder (10) made of an elastic polymer or copolymer, the plate holder (10) having a compressible surface center retention protrusion (13), a screw retention hole (11), and a plate receiving recess (14) having a recess wall (15); Including, the bone screws (41) are temporarily held in the screw retaining holes (11), the screw retaining holes (11) are aligned with the screw receiving openings (22), and the bone plate (20) is temporarily placed in the plate receiving recesses (14); A bone plate mounting assembly, wherein the bone plate (20) is removably held by the plate holder (10) with the body central retaining opening (21) attached to the compressible face central retaining protrusion (13), and the combination of the compressible face central retaining protrusion (13) and the body central retaining opening (21) alone is sufficient to removably hold the bone plate (20) to the plate holder (10).

2. 2. The bone plate mounting assembly of claim 1, wherein when one or more of the extension portions (24) are bent away from the plate holder (20) and out of the plate receiving recess (14), the bone plate (20) is removably retained to the plate holder (10) by a combination of the face center retaining protrusion (13) and the body center retaining opening (21).

3. 2. The bone plate mounting assembly of claim 1, wherein the recess wall (15) is compressible such that the recess wall (15) is compressed by a peripheral edge (23) of the bone plate (20) when the bone plate (20) is removably attached to the plate holder (10).

4. 4. The bone plate mounting assembly of claim 3, wherein when one or more of the extension portions (24) are bent away from the plate holder (20) and out of the plate receiving recess (14), the bone plate (20) is removably retained to the plate holder (10) by a combination of the face center retaining protrusion (13) and the body center retaining opening (21).

5. The bone plate mounting assembly of claim 1 , wherein the plate holder (10) is made of a single elastic polymer or copolymer.

6. The bone plate mounting assembly of claim 5, wherein the elastic polymer or copolymer has a Shore A hardness of about 40-100 and / or a Shore D hardness of about 10-90.

7. The bone plate mounting assembly of claim 5, wherein said resilient polymer or copolymer has a Shore A hardness of about 70-90.

8. 2. The bone plate mounting assembly of claim 1, wherein the extension portion (24) of the bone plate (20) is an arm extending outwardly from the body central retaining opening (21).

9. 2. The bone plate mounting assembly of claim 1, wherein the extension portion (24) of the bone plate (20) is a body portion that extends outwardly from the body central retaining opening (21).

10. The bone plate mounting assembly of claim 1 , wherein the plate holder (10) has a shape corresponding to the peripheral edge (23) of the bone plate (20).

11. The bone plate mounting assembly of claim 1 , wherein the plate holder (10) is made of silicone.

12. 3. The bone plate mounting assembly of claim 2, wherein at least one of the screw retaining holes (11) of the plate holder (10) remains aligned with at least one of the screw receiving openings (22) of the bone plate (20).

13. 2. The bone plate mounting assembly of claim 1, wherein a lateral dimension of said face central retaining protrusion (13) is slightly larger than a lateral dimension of said body central retaining opening (21).

14. 4. The bone plate mounting assembly of claim 3, wherein a lateral dimension of said plate receiving recess (14) is slightly smaller than a lateral dimension of said peripheral edge (23).

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