Bone plate implantation assembly

Abstract

A bone plate implant assembly having a plate holder (10) comprising an elastomeric polymer, a bone plate (20) and a bone screw (41), the plate holder (10) having a compressible mid-plane retaining protrusion (13) located within a plate receiving recess (14), and the bone plate (20) having a mid-body retaining hole (21), whereby the bone plate (20) is temporarily retained on the plate holder (10) by inserting the mid-plane retaining protrusion (13) into the mid-body retaining hole (21).

Description

Background Art

[0001] The present invention generally relates to the field of systems and assemblies for implanting bone plates of the type used to connect adjacent bone segments or cover an opening in a bone, the systems and assemblies comprising a hand-held screw guide device configured to temporarily retain one or more screws or similar mechanical fasteners in a fixed position and orientation aligned with screw receiving holes in a plate or similar member to be attached to the bone, wherein the screws are driven from the screw retaining guide through the screw receiving holes of the plate and into the bone to secure and attach the plate to the bone. The screw retaining device is commonly referred to as a screw guide, screw box or screw box. More specifically, the present invention relates to such a system or assembly wherein the screw retaining guide also serves as a bone plate bracket that temporarily retains the bone plate in an assembled unit, and further more specifically wherein the body of the screw retaining guide and bracket comprises a flexible, compressible, elastic material.

[0002] In the medical field, it is often necessary to attach a substantially rigid, ductile or even slightly flexible bone plate to a bone or a separate bone segment using mechanical fasteners, i.e., bone screws, such as a sternal plate attached to longitudinally separated sternal halves or a skull plate positioned across a skull opening. The bone plate has a plurality of screw receiving holes, threaded or unthreaded, through which the bone screws are driven into the underlying bone. In order to speed up the process of attaching the bone plate and ensure that the bone screws are driven into the bone at the appropriate angle, it is known to provide a hand-held screw holding guide device having a bore positioned to match the position of the screw receiving holes in the bone plate. The bone screws are temporarily placed in the bore holes provided in the screw guide, i.e., preloaded. The screw guide is then aligned with the bone plate or temporarily mounted to the bone plate, thereby properly positioning all the bone screws with their respective screw receiving holes, wherein, 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, thereby enabling the surgeon to position the bone plate at a desired location on the bone by grasping the screw guide and plate holder assembly.

[0003] The temporary retention of the bone plate on the screw guide and plate holder assembly can be achieved in various ways, such as by a clip, a friction or compression fit, a mechanical interlock, or by providing a recess in the screw guide to receive the bone plate. U.S. Patent No. 7,588,576 discloses an assembly in which a cylindrical guide / holder comprising an elastic material is provided with circumferentially spaced screw receiving bores that align with the screw receiving holes in the disc-shaped bone plate. The bone plate is temporarily retained by a circle of compressible elastic protrusions that are forced into correspondingly spaced and sized mounting holes present on the bone plate. U.S. Patent No. 9,572,611 shows another such assembly in which the bone plate is temporarily retained on the elastic screw guide / holder, for example by providing a recess on the adjacent side of the guide / holder that matches the configuration of the bone plate but is slightly smaller so that the bone plate is retained by pressing the bone plate into the recess. A problem encountered in these devices is that in many cases, the surgeon needs to bend the bone plate before attachment in order to better conform to the surface configuration or geometry of the bone. Since the plate is held to the abutment surface of the guide / cage by physical structures (protrusions, recessed walls) near or at the edge of the plate, bending of the plate often results in the screw guide and plate cage assembly being unable to hold the plate.

[0004] To address this problem, more complex structural designs of screw guide and plate holder assemblies have been proposed, such as shown in U.S. Patent Nos. 10,226,290 and 11,033,284 and U.S. Patent Publication No. 2021 / 0267650. The proposed solutions generally utilize clips or other mechanical connectors to couple the bone plate to the screw guide and plate holder assembly, which results in a bulky device and requires complex manufacturing.

[0005] The object of the present invention is to provide a flexible screw guide and bone plate holder attachment system or assembly which improves upon known systems by providing a screw guide and plate holder assembly comprising a uniform body of flexible and resilient compressible material without additional internal or external structural support members, the screw guide and plate holder assembly being provided in combination with a bone plate which is temporarily connected to or retained by the screw guide and plate holder assembly, wherein the screw guide and plate holder assembly is provided with a centrally located mid-body retaining projection which temporarily engages a centrally located mid-body mounting hole provided on the bone plate. The centrally located mid-body position allows the bone plate to remain in engagement with the screw guide and plate holder assembly even if the perimeter or extension arms of the bone plate have been bent as desired for fitting onto a bone surface. Such a screw guide and plate holder assembly is easy for the surgeon to operate, reduces manufacturing costs and does not require assembly of components. Summary of the invention

[0006] In general, the present invention is a bone plate implant system or assembly that includes a combination of a flexible screw guide and a bone plate holder, the flexible screw guide and the bone plate holder uniformly comprising an elastic polymer or copolymer, a bone plate constructed and configured for attachment to a bone, and a bone screw. The flexible screw guide and the bone plate holder are provided with a bore that receives and temporarily retains a bone screw, the screw retaining bore extending completely through the body of the bone plate holder and the flexible screw guide into a plate receiving recess disposed on a distal surface. A central mid-surface retaining projection is located within the plate receiving recess.

[0007] The bone plate is a thin, structurally rigid component that includes a screw receiving hole and a centered mid-body retaining hole. The configuration of the peripheral edge of the bone plate corresponds to the configuration of the plate receiving recess, and the overall lateral size of the bone plate around the peripheral edge is preferably slightly larger than the overall lateral size of the plate receiving recess. Preferably, the configuration of the centered mid-face retaining projection of the flexible bone plate support and screw guide and the centered mid-body retaining hole of the bone plate corresponds, and the lateral size of the centered mid-face retaining projection is slightly larger than the lateral size of the centered mid-body retaining hole. However, as long as there are enough parts, the configuration of the mid-face retaining projection can also be different from the configuration of the mid-body retaining hole. In this way, the bone plate is temporarily installed or combined with the flexible screw guide and the bone plate support by pressing the bone plate into the plate receiving recess, so that the mid-body centered retaining hole is compressed and maintained by the mid-face centered retaining projection, and preferably, the peripheral edge of the bone plate is compressed and maintained by the elastic properties of the recess wall.

[0008] The matching configuration of the plate receiving recess and the bone plate ensures proper alignment between the screw retaining bores of the flexible screw guide and the bone plate holder and the screw receiving holes of the bone plate, so that when the bone plate is properly positioned on the bone, the bone screws can be driven through the screw retaining bores and the screw receiving holes and then into the bone. When the bone plate is fixed to the bone, the flexible screw guide and the bone plate holder are easily removed from the bone plate.

[0009] The key advantage of the above assembly over the prior art devices is that a centered mid-face retention projection and a centered mid-body retention hole are provided as the primary means of temporarily retaining the bone plate on the flexible screw guide and bone plate support. In many cases, it will be necessary for the surgeon to adjust the bone plate to better conform to the bone surface, which can be accomplished by removing the bone plate from the assembly and bending the extension or some or all of the outer portions of the bone plate. In prior art systems, the bending of the bone plate renders the guide / support inoperable or less effective because the bent portion of the bone plate can no longer be connected or aligned with the retaining means of the guide / support. This problem can be overcome by securing the bone plate to the flexible screw guide and bone plate support primarily at or near the center or mid-body rather than at or near the peripheral edges because the central area will not be adversely affected by the reshaping of the outer portions of the bone plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 An exploded perspective view of an embodiment of the present invention is shown, wherein the bone plate is configured in a generally X-shape.

[0011] Figure 2 An exploded perspective view of an alternative embodiment of the present invention is shown wherein the flexible screw guide and plate holder are configured to mimic the configuration of an X-shaped plate.

[0012] Figure 3 Shows Figure 2 A distal view of an embodiment of the present invention.

[0013] Figure 4 Shown along Figure 2 A partially exposed side view taken along line 4-4 of an embodiment of the present invention illustrates the screw retaining bores of the bone plate bracket and the flexible screw guide and the screw receiving holes of the bone plate.

[0014] Figure 5 An exploded perspective view of another alternative embodiment of the present invention is shown wherein the flexible screw guide and bone plate holder are configured to mimic the configuration of a generally oval bone plate. DETAILED DESCRIPTION

[0015] The invention will now be described in detail with reference to the accompanying drawings, which are intended to be representative and illustrative rather than limiting in scope. The term "flexible" is used herein to cover a material having elastic properties, specifically, it is compressible but will return to its original configuration once the compressive bias is removed. To improve readability, the term "plate holder" is used herein as a shorthand substitute for the expanded term "flexible screw guide and bone plate holder", so that the use of the former is equivalent to the use of the latter. The term "distal" is used herein to indicate the direction toward the bone when the assembly is positioned on the bone in use, so that the distal side of the plate holder is the side that holds the bone plate when assembled. The term "lateral" is used herein to indicate a lateral direction that is generally perpendicular to the distal direction.

[0016] Figure 1 shows a basic embodiment of the components or systems described herein, and Figure 2 A more ergonomic configuration of the plate holder 10 is shown. The present invention is generally an assembly, system or combination of the plate holder 10, the bone plate 20 and the bone screw 41. The bone plate 20 is temporarily mounted on or held by the plate holder 10 by the elastic properties of compression or biasing, so that the bone plate 20 is retained on the plate holder 10 during movement and positioning, and once the bone plate 20 is attached to the bone, the plate holder 10 is easily removed from the bone plate 20 by hand force.

[0017] Bone plates 20 are well known in the art. Such implants are used to combine broken or separated bone segments, such as a severed sternum, in a relatively rigid and fixed relationship to allow healing and mechanical support, and also to cover gaps or openings in the bone, such as a burr hole in the skull. The bone plate 20 is provided with screw receiving holes 22 so that bone screws 41 can be inserted through the screw receiving holes 22 and into the bone to secure the bone plate 20 to the bone. The bone plate 20 comprises a biocompatible material having suitable strength properties, such as titanium, ceramic, or the like. The bone plate 20 is generally thin in thickness, and its peripheral edge 23 defines the configuration or shape of the bone plate 20. A typical bone plate 20 may be substantially or approximately rectangular, circular, oval ( Figure 5 ) or X-shaped ( Figure 1 -3), such that these structures can define an extension 24, which can include an extended body portion or arm. The bone plate 20 can be malleable, such that the extension 24 or the entire bone plate 20 can be bent before being attached to the bone to better approximate or match the surface structure of the bone.

[0018] The bone plate 20 of the present invention is provided with a centered mid-body retention opening 21 that is significantly larger than the screw receiving holes 22. The shape of the mid-body retention opening 21 can vary, but a non-circular mid-body retention opening 21 is preferred to better ensure proper alignment and orientation of the bone plate 20 on the plate holder 10. For symmetrical bone plates 20 having a true center, the center of the mid-body retention opening 21 is preferably aligned with the true center. For other bone plate 20 configurations, a suitable mid-body position is determined so that the bend or any bone plate extension 24 does not negatively affect the retention of the bone plate 20 by the plate holder 10.

[0019] The plate holder 10 is a uniform body comprising an elastic polymer or copolymer, such as silicone, so that the plate holder 10 is flexible, compressible, and maintains a neutral shape when any compressive or biasing force is removed. The polymer should be approved for patient contact or implantability and preferably have a Shore A hardness range of about 40-100 and / or a Shore D hardness range of about 10-90. Most preferably, the Shore A hardness range is about 70-90. No internal or external support members or components or reinforcement members or components are required.

[0020] The overall configuration or shape of the board support 10 can vary. In a basic embodiment, the board support can be block-shaped ( Figure 1 ), but preferably, the shape of the plate holder 10 better approximates the structure of the bone plate 20 ( Figure 2 , Figure 3 , Figure 5), because this provides the surgeon with a better visual effect of the position of the bone plate 20 during insertion and fixation to the bone. The matching configuration of the bone plate 20 and the plate holder 10 can also provide the surgeon with a more ergonomic or more comfortable grip. The plate holder 10 can be provided with an alignment indicator 16 or other markings.

[0021] The plate holder 10 is provided with screw retaining bores 11 configured to temporarily retain bone screws 41. The number and location of the screw retaining bores 11 correspond to the number and location of the screw receiving holes 22 in the bone plate 20. The screw retaining bores 11 extend completely through the plate holder 10, opening into a plate receiving recess 14 located in the distal surface 12 of the plate holder 10. The screw retaining bores 11 may have a simple tubular structure, but are preferably provided with screw retaining structures 30, such as annular or longitudinal ribs, which retain and properly orient the bone screws 41 while allowing the bone screws 41 to be easily driven from the screw retaining bores 11 through the screw receiving holes 22 of the attached bone plate 20 and into the bone. Figure 4 One suitable configuration is shown in which the screw retaining bore 11 includes a ridged screw retaining structure 30, a narrowed alignment neck 31, and a flared distal opening 32. The screw retaining bore 11 on the right is shown retaining a relatively short bone screw 41, while the screw retaining bore 11 on the left retains a much longer bone screw 41. The flared distal opening 32 combined with the inherent flexibility of the plate holder 10 allows the bone screw 41 to be inserted into the bone plate 20 at an angle of up to about 20 degrees from vertical when the extension 24 has been bent to better conform to the bone surface.

[0022] The plate holder 10 is provided with a plate receiving recess 14 disposed on the distal surface 12 of the plate holder 10. The plate receiving recess 14 has a recess wall 15 and is configured to correspond or match the configuration of the bone plate 20, i.e., the configuration or shape of the recess wall 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 when the bone plate 20 is mated with the plate holder 10, the screw retaining bore 11 of the plate holder 10 is properly aligned with the screw receiving hole of the bone plate 20. Most preferably, the lateral dimension of the plate receiving recess 14 is slightly smaller than the lateral dimension of the peripheral edge 23 of the bone plate 20, so that the insertion of the bone plate 20 into the plate receiving recess 14 biases or compresses the recess wall 15 outwardly, thereby providing temporary retention of the bone plate 20 by the plate holder 10. In order to ensure proper initial contact between the bone plate 20 and the bone when implanted, the depth of the plate receiving recess 14 is most preferably equal to or less than the depth of the bone plate 20.

[0023] The plate holder 10 is also provided with a central, compressible midface retention projection 13 located within the plate receiving recess 14. When the bone plate 20 is mounted to the plate holder 10, the midface retention projection 13 is positioned and configured to correspond to the location and configuration of the midbody retention hole 21 of the bone plate 20. The lateral dimension of the midface retention projection 13 is slightly larger than the lateral dimension of the midbody retention hole 21, so that the insertion of the bone plate 20 into the plate receiving recess 14 of the plate holder 10 biases or compresses the midface retention projection 13 inwardly, thereby providing temporary retention of the bone plate 20 by the plate holder 10. Preferably, the overall peripheral configuration of the midface retention projection 13 generally corresponds to or matches the overall configuration of the midbody retention hole 22 of the bone plate 20. However, the configuration of the midface retention projection 13 may be different from the configuration of the midbody retention hole 22 of the bone plate 20, as long as a sufficient portion of the midface retention projection 13 is compressed to retain the bone plate 20 on the plate holder 10. For example, the mid-body retention hole 22 of the bone plate 20 can be rectangular, while the mid-face retention projection 13 can be formed as a slightly larger cross. The mid-face retention projection 13 and other parts of the plate holder 10 can be provided with one or more internal bores or channels to reduce the amount of material and / or increase flexibility.

[0024] For use, the bone screw 41 is inserted into the screw retaining bore 11 of the plate holder 10, and the bone plate 20 is mounted in the plate receiving recess 14 of the plate holder 10, and the mid-body retaining hole 21 of the bone plate 20 compresses or biases the elastic mid-surface retaining protrusion 13 located in the plate receiving recess 14, so that the bone plate 20 is temporarily retained by the plate holder 10. This combination defines a bone plate implant assembly. The surgeon then grasps the plate holder 10 and positions the bone plate 20 at the desired position on the bone. The bone screw 41 is then driven through and out of the screw retaining bore 11, through the screw receiving hole 22 of the bone plate 20 and into the bone. Once the bone plate 20 is attached to the bone, the surgeon pulls the plate holder 10 away from the bone plate 20.

[0025] In the event that the bone plate 20 needs to be bent or otherwise adjusted to better conform to the bone surface configuration, the bone plate 20 is pulled out of the plate holder 10 and the surgeon adjusts the bone plate 20 by bending, tilting or otherwise shaping the extensions 24 of the bone plate 20, which may result in one or all of the extensions 24 no longer cooperating with or fitting into the plate receiving recess 14. The structure of the plate holder 10 and the bone plate 20, particularly the presence of the midface retention projections 13 and the midbody retention holes 22, allows the bone plate 20 to be reattached to the plate holder 10 simply by a compression or biased fit between the midface retention projections 13 and the midbody retention holes 22. The attachment procedure is then performed as described.

[0026] Depending on the flexibility, elasticity and thickness of the plate holder 10, the configuration of the bone plate 20 and plate holder 10, the location of the screw receiving holes 22, the size and extent of the extensions 24, the length of the bone screws 41 and other variables, it is possible that bending the bone plate extensions more than about 20 degrees out of plane may prevent the bone plate 20 from being secured to the bone using the screw retaining bores 11 in the outermost or highly curved portion because the angle between the axis of the screw retaining bores 11 relative to the axis of the screw receiving holes 22 in the bone plate 20 will become too large. In this case, the adjusted bone plate 20 is reinstalled onto the plate holder 10 using the combination of the midface retaining projections 13 and the midbody retaining holes 22. The bone plate 20 is then properly positioned and affixed to the bone using the bone screws 41 retained in at least one of the remaining functional screw retaining bores 11, i.e., in the innermost or flattest area relative to the bone plate 20, which maintains alignment with at least one of the screw receiving holes 22. The plate holder 10 is then separated from the bone plate 10 and the bone screws 41 are inserted and driven directly through the remaining screw receiving holes 22 into the bone.

[0027] Alternatively, the screw receiving bore 11 can be used as a drill guide to drill a pilot hole in the bone for the bone screw 41. After the bone screw 41 is removed from the plate holder 10 and the bone plate 20 mounted on the plate holder 10 is properly positioned against the bone, the surgeon inserts the drill bit into the empty screw receiving bore 11 and drills the pilot hole. The bone screw 41 is then inserted or reinserted into the screw receiving bore 11 and the attachment procedure is performed as described.

[0028] It is to be understood that equivalents and alternatives to some of the above-described elements and structures may be apparent to those skilled in the art, and thus, the true scope and definition of the invention should be indicated by the following claims.

Claims

1. Bone plate implant assembly, including: A bone plate (20) comprising a mid-body retaining hole (21), a screw receiving hole (22), a peripheral edge (23) and an extension (24); a bone screw (41); and A plate holder (10) comprising an elastic polymer or copolymer, a compressible mid-surface retaining projection (13), a screw retaining bore (11) and a plate receiving recess (14) having a recess wall (15); wherein the bone screw (41) is temporarily retained in the screw retaining bore (11), the screw retaining bore (11) is aligned with the screw receiving hole (22), and the bone plate (20) is temporarily positioned in the plate receiving recess (14); and wherein the bone plate (20) is removably retained by the plate holder (10) by mounting the mid-body retaining hole (21) onto the compressible mid-surface retaining protrusion (13), and wherein the combination of the compressible mid-surface retaining protrusion (13) and the mid-body retaining hole (21) is sufficient in itself to removably retain the bone plate (20) on the plate holder (10).

2. The bone plate implant assembly according to claim 1, characterized in that: The bone plate (20) is removably retained on the plate holder (10) by the combination of the mid-surface retaining projection (13) and the mid-body retaining hole (21) by bending one or more of the extensions (24) away from the plate holder (10) and out of the plate receiving recess (14).

3. The bone plate implant assembly according to claim 1, characterized in that: The recess wall (15) is compressible so that when the bone plate (20) is removably mounted on the plate holder (10), the recess wall (15) is compressed by the peripheral edge (23) of the bone plate (20).

4. The bone plate implant assembly according to claim 3, characterized in that: By bending one or more of the extensions (24) away from the plate holder (10) and away from the plate receiving recess (14), the bone plate (20) is detachably retained on the plate holder (10) by the combination of the mid-surface retaining projections (13) and the mid-body retaining holes (21).

5. The bone plate implant assembly according to claim 1, characterized in that: The plate support (10) comprises a single elastic polymer or copolymer.

6. The bone plate implant assembly according to claim 5, characterized in that: The elastomeric polymer or copolymer has a Shore A hardness range of about 40-100 and / or a Shore D hardness range of about 10-90.

7. The bone plate implant assembly according to claim 5, characterized in that: The elastomeric polymer or copolymer has a Shore A hardness range of about 70-90.

8. The bone plate implant assembly according to claim 1, characterized in that: The extension (24) of the bone plate (20) is an arm extending outward from the mid-body retaining hole (21).

9. The bone plate implant assembly according to claim 1, characterized in that: The extension portion (24) of the bone plate (20) is a main body portion extending outward from the mid-body retaining hole (21).

10. The bone plate implant assembly according to claim 1, characterized in that: The plate holder (10) has a shape corresponding to the outer peripheral edge (23) of the bone plate (20).

11. The bone plate implant assembly according to claim 1, characterized in that: The plate holder (10) comprises silicone.

12. The bone plate implant assembly according to claim 2, characterized in that: At least one of the screw-retaining bores (11) of the plate holder (10) is always aligned with at least one of the screw-receiving holes (22) of the bone plate (20).

13. The bone plate implant assembly according to claim 1, characterized in that: The lateral dimension of the middle surface retaining protrusion (13) is slightly larger than the lateral dimension of the middle body retaining hole (21).

14. The bone plate implant assembly according to claim 3, characterized in that: The lateral dimension of the plate receiving recess (14) is slightly smaller than the lateral dimension of the peripheral edge (23).

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