Pivot fastener for bone / cranioplasty implants and prosthesis

Abstract

To provide implanted medical devices to interconnect bone portions to one another.SOLUTION: An assembly comprises a cranioplasty prosthesis component having a connection hole. A pivot fastener may have a body being threaded and adapted to be screwed to cranium bone. A shoulder is between the body and a head of the pivot fastener, and has a circular section. A diametrical dimension of the circular section is less than a diametrical dimension of the connection hole, such that the shoulder forms a rotational joint with the cranioplasty component when the shoulder is in the connection hole.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] (Cross - reference to related applications) This application claims priority to U.S. Patent Application No. 63 / 613981, filed on December 22, 2023, and U.S. Patent Application No. 63 / 635847, filed on April 18, 2024. The entire contents of both are incorporated herein by reference.

[0002] This application relates to implants, attachment devices, fixation plates, plating systems, and / or prostheses used in surgical procedures such as craniotomy, craniectomy, and / or craniofacial surgery, orthopedics, etc. Among them, for example, it relates to fasteners used with such devices and implants.

[0003] Various types of implantable medical devices for interconnecting bone parts have been developed, and among such implantable medical devices, some allow movement between bone parts. For example, a craniotomy is a procedure in which a bone flap is temporarily removed to access a part of the brain, blood vessels, or similar soft tissue within the skull. In a craniotomy, the bone flap is re - implanted at the end of the procedure, before closing the skin. A craniectomy is a procedure in which the bone flap is permanently removed from the remaining part of the skull.

[0004] Dynamic systems have been developed that move a bone flap to expand the intracranial volume, thereby enabling "decompressive craniotomy." Such dynamic systems may typically include a telescoping or spring-based expansion portion. However, such systems may be bulky and may exhibit unnecessary resistance to the movement of the bone flap or prosthesis, thereby providing insufficient decompression. Additionally, inherently bulky dynamic systems may be unesthetic in that they may create bumps on a person's head. Similarly, dynamic systems used in other procedures such as distraction surgery may also be bulky. SUMMARY OF THE INVENTION

[0005] In a first aspect, an assembly is provided that includes a prosthesis element having at least one connection hole and a pivot fastener having a body portion adapted to be received within bone, a head, and a shoulder between the body portion and the head, the shoulder having a circular section, wherein the radial dimension of the circular section is smaller than the radial dimension of the connection hole, and the shoulder forms a rotational joint with the prosthesis element when the shoulder is within the connection hole.

[0006] Further, according to the first aspect, for example, the shoulder has a pivot segment adjacent to the head and an abutment portion adjacent to the body portion.

[0007] Additionally, according to the first aspect, for example, the pivot segment has a cylindrical shape.

[0008] Additionally, according to the first aspect, for example, the abutment portion is an abutment segment.

[0009] Furthermore, according to the first aspect, for example, the abutment segment has a tapered shape that tapers towards the main body portion.

[0010] Furthermore, according to the first aspect, for example, the diameter of the base of the tapered shape is equal to the diameter of the pivot segment at the joint between the base and the pivot segment.

[0011] Furthermore, according to the first aspect, for example, the tapered shape is a frustum of a cone shape.

[0012] Furthermore, according to the first aspect, for example, the abutment segment has a taper angle of up to 45 degrees in total and greater than 0 degrees.

[0013] Furthermore, according to the first aspect, for example, the tapered shape is a truncated spherical shape.

[0014] Furthermore, according to the first aspect, for example, the head has a diameter larger than the maximum diameter of the shoulder, and the head is received within the counterbored hole of the connection hole of the prosthesis element.

[0015] Furthermore, according to the first aspect, for example, the lower surface of the head has a tapered shape that tapers towards the shoulder.

[0016] Furthermore, according to the first aspect, for example, the main body portion has a frustum-shaped shank portion that supports at least one thread.

[0017] Furthermore, according to the first aspect, for example, the shoulder has a diameter that is 1.00 mm ± 0.25 mm larger than the maximum diameter of the shank.

[0018] Furthermore, according to the first aspect, for example, the main body portion has a conical tip portion.

[0019] Furthermore, according to the first aspect, for example, the main body portion has a thread, and the head portion has a drive portion.

[0020] Furthermore, according to the first aspect, for example, the prosthesis element is an attachment device having a main body portion defined from a sheet material, and a first connection end, wherein the first connection end has at least one of the connection holes, and at least one of the connection holes is configured to cooperate with one of the pivot fasteners to fix the attachment device to a bone flap or prosthesis covering at least a part of the opening in the skull; a second connection end, wherein the second connection end has at least one of the other connection holes, and at least one of the other connection holes is configured to cooperate with one of the other pivot fasteners to fix the attachment device adjacent to the opening in the skull; a frame portion extending from the first connection end; and a coil portion between the frame portion and the second connection end, the coil portion having struts configured to deform by bending and webs between the struts configured to deform by torsion. The frame portion is disposed on the periphery of the opening in the skull and is configured to prevent inward movement, and the coil portion enables out-of-plane deformation of the attachment device with respect to the first connection end such that the coil portion moves outward of the neutral plane together with the second connection end.

[0021] Furthermore, according to the first aspect, for example, the main body portion extends in the longitudinal direction from the first connection end to the second connection end, and at least some of the struts extend at least partially in the longitudinal direction.

[0022] In addition, according to the first aspect, for example, the prosthesis element is an attachment device having a body portion defined from a sheet material, and has a first connection end having at least one hole configured to receive a fastener to fix the attachment device to a first bone portion, and a second connection end having at least one connection hole configured to cooperate with one of the pivot fasteners to fix the attachment device to a second bone portion, a frame portion extending from the first connection end, and a coil portion between the frame portion and the second connection end, the coil portion having struts configured to deform by bending and webs between the struts configured to deform by torsion, the frame portion being configured to be disposed on a separation line or a bone end line between the first bone portion and the second bone portion, and the coil portion enabling deformation of the attachment device about the first connection end such that it expands in a plane.

[0023] In addition, according to the first aspect, for example, the frame portion is a straight segment.

[0024] In addition, according to the first aspect, for example, the at least one hole in the first connection end is at least one of the connection holes configured to cooperate with one of the pivot fasteners.

[0025] Reference is now made to the accompanying drawings.

Brief Description of the Drawings

[0026]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11A

Figure 11B

Figure 11C

Figure 12

Figure 13

DETAILED DESCRIPTION OF THE INVENTION

[0027] Referring to the drawings, and more particularly to FIG. 1, a cranioplasty prosthesis 10 that can use the pivot fastener F according to the present disclosure is shown at 10, which is shown as one possible use of the pivot fastener F. The cranioplasty prosthesis 10, attachment device 20, and prosthesis blade 30 described herein may be those described in International Publication No. WO 2023 / 070200 filed on Oct. 25, 2022, the content of which is incorporated herein by reference. The cranioplasty prosthesis 10 is shown as spanning an opening S1 in the skull S. The opening S1 can occur, for example, by craniectomy. For simplicity, a single cranioplasty prosthesis 10 is shown, and thus the opening S1 in the skull S is only partially covered, but a plurality of cranioplasty prostheses 10 can be used in a side-by-side arrangement.

[0028] The above-mentioned cranioplasty prosthesis 10 is of the type that temporarily or permanently covers the opening S1, for example, related to a craniotomy or cranioplasty procedure. The expression "cranioplasty" is used as a designation for the prosthesis 10 in that the prosthesis 10 serves to cover the opening S1 in the skull S. The use of the cranioplasty prosthesis 10 is described in the context of a craniotomy, craniectomy, or cranioplasty procedure, but it can also be used under other conditions.

[0029] According to one modification of the present disclosure, the skullplasty prosthesis 10 is shown such that a pair of attachment devices 20 are fabricated at the ends of the prosthesis blade 30 on opposite sides of each other. This attachment device 20 can be deformed to enable adjustment of the prosthesis blade 30 with respect to the skull S. On the other hand, the prosthesis blade 30 defines a structural component of the skullplasty prosthesis 10 that serves as a temporary or permanent skull shell portion covering the opening S1. Further, the prosthesis blade 30 can be shaped, for example, from a formable material such as a metal plate, so that the prosthesis blade 30 has a predetermined curvature that provides appropriate impact resistance for protecting the brain while being continuous with the surface of the surrounding skull. In the embodiments shown in FIGS. 1-2, the attachment device 20 and the prosthesis blade 30 are of a monoblock structure. For example, the attachment device 20 and the prosthesis blade 30 may be made from a single sheet material that can be cut by any suitable method such as laser cutting, CNC machining, casting, etc. It is also possible to mechanically attach the attachment device 20 to the prosthesis blade 30 so as to have three separate components. For example, the attachment device 20 can be fixed to the prosthesis blade 30 by, for example, screws, welding, adhesion, etc. Further, the attachment device 20 can also be used as a fixture for the bone flap, that is, together with the prosthesis blade 30.

[0030] According to one modification of the present disclosure, the skullplasty prosthesis 10 may have only one attachment device 20, that is, it may have it only at one end of the prosthesis blade 30, and at the other end, the prosthesis blade 30 may be directly fixed to the skull. According to another modification, the prosthesis blade 30 can also be used together with other fixing means, such as screws, provided to fix the prosthesis blade 30 to the skull S without the attachment device 20. Such a prosthesis blade 30 may not be able to enable dynamic adjustment of the shape covering the opening S1, and may not be able to address, for example, the problem of intracranial pressure, but still, it can form a prosthesis valve that provides appropriate structural integrity. Furthermore, while the prosthesis blades 30 can be shaped to have a predetermined geometric shape that conforms to the outer surface of the surrounding skull, since they are thinner compared to bone flaps, they can also reduce the pressure to some extent.

[0031] An enlarged view showing that the attachment device 20 can be fixed to the bone of the skull by the pivot fastener F according to a variant of the present disclosure is provided in FIG. 2. The planar body portion of the cranioplasty prosthesis 10 can be made of a biocompatible material or a combination of materials such as metal or polymer. For example, titanium, for example titanium in sheet form, is well suited for use in defining the cranioplasty prosthesis 10. This material is a rigid material, but since its thickness is limited, it can also exhibit some flexibility. Thus, the cranioplasty prosthesis 10 can have portions that can deviate from the plane and deform (for example, when the cranioplasty prosthesis 10 is made from a sheet). This deformation may be within the elastic deformation range or may reach plastic deformation, for example, to conform to the shape of the surrounding outer surface of the skull. By using a rigid material and having a width and length that are significantly larger than the thickness, in-plane deformation, i.e., the cranioplasty prosthesis 10 deforming while remaining planar, may be impossible. However, as will be described later, the pivot fastener F cooperates with other parts of the cranioplasty device 10 to allow some in-plane deformation. The cranioplasty prosthesis 10 may, by its configuration, resist buckling.

[0032] The out-of-plane deformation of the prosthesis blade 30 can enable the user to manually define the shape of the prosthesis blade 30, for example, to mimic the geometric shape of the removed bone flap. In one variant, the shape can be obtained by applying the prosthesis blade 30 to the target point on the skull S prior to craniotomy. Optionally, an instrument may be used to shape the blade 30. For example, a measuring instrument capable of mimicking the shape of the skull may be used, and a physical shape representation may be obtained. Blades 30 of different lengths may be placed side by side, and the shape of the flap composed of a plurality of blades 30 may be adjusted. The elongated nature of the blade 30 can facilitate insertion into the small incision associated with, for example, endoscopic surgery, regardless of whether it is part of the skull formation prosthesis 10. When multiple blades are used, a single incision sized based on the width of a single blade 30 can be used for the insertion of all blades 30. Further, although optional, the rounded ends of the blade 30 have no corners, so when used in minimally invasive surgery, for example, when the blade 30 is slid into place by pushing the rear end of the blade 30 or the skull formation prosthesis 10, the risk of catching the surrounding soft tissue is reduced. For the blade 30, not only the geometric shape of the end portion that is semicircular as shown, but also other tapered shapes are conceivable.

[0033] Referring to FIG. 3, an exemplary embodiment of the attachment device 20 is provided. The attachment device 20 can be used with the pivot fastener F of the present disclosure. As described above, the attachment device 20 may or may not be part of the cranioplasty prosthesis 10. For example, the attachment device 20 may be used alone to attach the skull to a bone flap, a prosthesis shell, or a prosthesis different from the prosthesis blade 30. The attachment device 20 is designed to allow a constrained relative movement between a bone flap, a prosthesis shell, or a prosthesis covering the opening S and the skull surface around the opening S. This movement can be described as a mostly out-of-plane, bidirectional residual movement of length L, to which the pivot fastener F described below can contribute.

[0034] The attachment device 20 of FIG. 3 is shown to have a planar body portion and can be made in a monoblock structure from a sheet material. For example, the attachment device 20 of FIG. 5 may be made from a single sheet material that can be cut by any suitable method such as laser cutting, CNC machining, casting, etc. For reference, in the neutral position, the attachment device 20 can lie in a plane defined by the length L and the width W. This neutral position can be the natural state of the attachment device 20. The plane defined by the length L and the width W may be a flat plane, but may have, for example, a curved shape, i.e., a curved surface.

[0035] The attachment device 20 has a first connection end 21 and a second connection end 22. The first connection end 21 is defined by a pair of holes 21A configured to receive the pivot fastener F of FIG. 5. There may be fewer or more holes 21A. Similarly, the second connection end 22 also has a pair of (or more or fewer) holes 22A for receiving the pivot fastener F of FIG. 5. In one embodiment, the holes 21A are arranged in sequence along the width W. Similarly, in one embodiment, the holes 22A are arranged in sequence along the width W. Other arrangements are also conceivable. In one variant, the holes 21A and / or the holes 22A have a circular shape as shown (e.g., a straight hole, a countersunk hole, a countersunk hole). Accordingly, the pivot fastener F is received within the holes 21A and / or 22A (if present and if a pivoting motion is required), defining a rotational joint as described below. Accordingly, the rotational joint can enable a rotational movement about the rotational axis H1, as shown by R in FIG. 4 and described below. The rotational axis H1 can be generally parallel to the height (perpendicular to the plane of FIG. 3).

[0036] The first connection end 21 and the second connection end 22 are interconnected by, for example, a coil portion 23 formed from a plurality of coils or by a frame portion 24. Also, the coil portion 23 can also be referred to as a switchback mechanism and has a plurality of switchback portions. In use, the attachment device 20 has the first connection end 22 fixed to the skull S adjacent to the opening S1 of the skull. The second connection end 21 can be connected to a bone flap or prosthesis covering the opening S1 of the skull, such as the prosthesis blade 30 or the like. The reverse arrangement is also possible, but not always appropriate. The first connection end 21 is shown as having holes for screwing to components, but the first connection end 21 may be integrally connected to the blade portion 30 as shown in FIG. 1.

[0037] The coil portion 23 is responsible for enabling out-of-plane movement of the second connection end 22 with respect to the first connection end 21 and with respect to the attachment device 20 in its neutral position (also referred to herein as the original state). The coil portion 23 is configured to restrict the movement of the first connection end 21 such that the first connection end 21 actually overlaps itself at height H. The rotational joint at the end 22 enabled by the pivot fastener F can contribute to this pseudo-overlap. In other words, the coil portion 23 is arranged to restrict the first connection end 21 to movement along height H. The first connection end 21 can also move along length L, but when projected onto the neutral plane (i.e., in the original state), the change in distance along length L is substantially smaller than the change in distance along height H. In other words, the connection end 21 is generally overlapped in height before and after deformation, but considering the radial expansion on the sphere, the connection end 21 needs to move (diagonally) along the length direction with respect to 22 before and after deformation. From the above, 21 may appear to be only in motion along its height. On the other hand, the frame portion 24 is between the first connection end 21 and the coil portion 23. The frame portion 24 is a rigid component that can optionally be placed on a kerf (i.e., no in-plane deformation), and can be placed on the kerf so as to enforce the unidirectional deformation characteristic of the attachment device 20, i.e., to enable upward movement from the neutral state, as will be explained below. Thus, the movement of the first connection end 21 in the width W direction is restricted or made negligible by the physical restraint imposed by the frame portion 24. As can be observed, the coil portion 23 is connected to the frame portion 24, and the frame portion 24 enables various types of deformation of the coil portion 23. In one deformation example, the frame portion 24 can deform by bending only. This movement, although described as that of the first connection end 21, similar behavior may also apply to the second connection end 22 with respect to the first connection end 21. In one embodiment, during use, it is the second connection end 22 that leads when being slid into the incision.Although not required, the flare shape from the leading end towards the trailing hole 22A and the rear position of the hole 22A relative to the tip of the coil portion 23 in the direction L limit the movement in the H direction and further contribute to maintaining the attachment device 20 in a planar shape and to moving along the surface of the skull. The above-described flare shape from the leading end towards the trailing hole 22A may be expressed as being arcuate if it exists, or may have other shapes.

[0038] The coil portion 23 and the frame portion 24 have various components that restrict the relative movement of the ends 21 and 22. The coil portion 23 has struts 23A that at least partially extend in the length L direction. The struts 23A can be interconnected by webs 23B. The webs 23B may be shorter than the struts 23A and may be disposed at the ends of the struts 23A. For example, the webs 23B may be in a direction transverse to the struts 23A and at least partially extend in the width W direction. Thus, when one of the ends 21 and 22 receives a force, the web 23B deforms due to the lever effect of the strut 23A as shown in FIG. 6, allowing out-of-plane movement of the strut 23A. The web 23B acts as a rotational joint (along W) due to the deformation. Although the struts 23A and the webs 23B are described as having different features, the coil portion 23 may have curved sections that act as the struts 23A and the webs 23B, and the web 23B is at the junction with other struts 23A to which the curved section is connected. In this case too, the struts 23A and the webs 23B can all be formed from a single sheet material. In one variation, the web 23B can be said to exhibit torsion when out-of-plane movement occurs for the strut 23A. Parallel to the torsion of the web 23B, the strut 23A can exhibit bending of the out-of-plane movement. In one variation, such torsion can be elastic deformation (although it can also be plastic deformation in some cases). When undergoing deformation, the attachment device 20 can be defined as a compliant mechanism, i.e., a flexible body that elastically deforms. Further, due to its configuration, the attachment device 20 can be said to be unidirectional in its displacement from its original state in that it can move only in one direction, i.e., towards the deformed state, from its original state (neutral plane). In its original state, the attachment device 20 cannot move in other directions through normal forces and pressures during use. In other words, the attachment device 20 cannot deform in the negative H direction from the neutral plane / original state.This is because the frame portion 24 of the attachment device 20 is essentially in a direction crossing and above the kerf between the skull and the valve, and the attachment device 20 prevents the inward movement of the valve, i.e., the dent of the bone valve. The frame portion 24 is shown as having a strut 24A to which a coil portion 23 is connected at its first end. The coil portion 23 can be said to be divided into two sets of coils from the strut 24A of the frame portion 24. In one variant, the strut 24A extends along a length L. Other arrangements are possible, such as having multiple pairs of the strut 24A for example. The frame portion 24 may further include a frame member 24B, and a connection hole 21A of the first connection end 21 may be arranged at its end. Therefore, since there is no coil portion, the deformation of the frame portion 24 is restricted in contrast to the coil portion 23. This can be observed in FIG. 4.

[0039] In fact, as observed from FIG. 4, the rotation of the first coil portion in the direction R when the attachment device 20 moves outside the neutral plane, i.e., the rotation about the axis H1 (see FIG. 6), is enabled by the rotational joint at the end 22 using the pivot fastener F (see FIG. 5). This can be made possible by the fact that the connection holes 22A are each connected to the respective coils of the coil portion 23 that were described as a set above. This rotation causes the expansion of the attachment device 20 along the direction L (as can be observed from the figures arranged side by side on the left and right of FIG. 4), which contributes to the footprint of the attachment device 20 in the deformed state approaching the footprint in the neutral state. It can also be observed that the coil portion 23 has a segment in the opposite direction of the connection end 21 with respect to the line passing through the centers of both of the connection holes 22A. This can result in a larger span of the movement of the first connection end 21 with respect to the second connection end 22.

[0040] In one variation, the second connection end 22, i.e., the second connection end 22 that characterizes the rotary joint, is on the skull, while the first connection end is connected to the valve or is connected to the blade 30. The first connection end 21 has a single member that interconnects with the hole 21A, and there may be no substantial rotation in the hole 21A.

[0041] By combining various movements with deformations occurring within the range of elastic deformation, i.e., by combining rotation, torsion, and bending, the line plotted with displacement against force can exhibit non-linear behavior (in contrast to a spring-like system that follows Hooke's law), and thus, the ratio of displacement to force can be greater. This can be useful when reducing intracranial pressure.

[0042] The configuration of the attachment device 20 is not limited to that shown in FIGS. 3 - 4, and other configurations, such as those shown in FIGS. 11A - 11C and 12, are also conceivable.

[0043] For example, by the pivot movement being enabled, for example, by the pivot fastener F of the present disclosure, the attachment device 20 is well-suited for fixing a prosthesis or a bone flap to the skull and enables dynamic unidirectional movement, i.e., it enables movement essentially limited to the displacement of the connection end 21 or 22 in the height H direction from the neutral plane, and in some cases, in the direction back towards the neutral plane. Thus, the attachment device 20 enables the displacement of the bone flap or prosthesis as a reaction to intracranial pressure. As a result, the damage caused by increased intracranial pressure can be suppressed due to the increase in the intracranial volume. In its neutral position, the attachment device 20 provides its maximum shear stress, thereby preventing the inward movement of the bone flap or prosthesis. Also, the flare shape from the front end towards the hole 22A can contribute to preventing the inward movement. The attachment device 20 may be made from any suitable material such as metal and plastic, which is semi-flexible, biocompatible, and / or biodegradable.

[0044] The attachment device 20 can be used in a hybrid manner, for example, by being used as part of the cranioplasty prosthesis 10 or for connecting a bone flap to other parts of the skull. For example, in the latter scenario, when dealing with intracranial pressure problems, although the cranioplasty prosthesis 10 is not as optimal as (since the prosthesis blade 30 is substantially thinner than the bone flap), the presence of the attachment device 20 can enable the formation of some decompression.

[0045] The attachment device 20 can be used to treat some lesions caused by trauma, subdural hematoma, subarachnoid hemorrhage, intracerebral hemorrhage, cerebral venous thrombosis, meningitis, empyema, osteomyelitis, hydrocephalus, tumors, or similar intracranial diseases. Using the cranioplasty prosthesis 10, attachment device 20, and / or prosthesis blade 30 of the present disclosure, it is possible to treat increased intracranial pressure in a single surgery. By doing so, the risk of complications can be greatly reduced, and the patient's recovery time can also be shortened. Furthermore, postoperative complications can be avoided with a single intervention. The cranioplasty prosthesis 10 is a universal and dynamic bone flap prosthesis that can be transplanted during craniotomy or craniectomy. The cranioplasty prosthesis 10 not only forms an efficient protection against impact but can also bring about a decrease in intracranial pressure, and the surgical cost related to the use of the cranioplasty prosthesis 10 can be reduced. Conveniently, the attachment device 20 can provide sufficient displacement even using autologous bone flaps or synthetic bone flaps.

[0046] Referring to the drawings, and more particularly to FIGS. 5 and 6, one of the pivot fasteners F is shown in more detail. The pivot fastener F has a body portion 100, a head portion 110, and a shoulder portion 115 between the body portion 100 and the head portion 110. The body portion 100 is part of the pivot fastener F that enters the bone, for example, by a thread. The head portion 110 remains outside the bone and has a drive portion that is interfaced with tools such as a screwdriver, a robot, a drill, etc. for the rotation applied to the pivot fastener F for screwing the body portion 100 into the bone or unscrewing it from the bone. The shoulder portion 115 is configured to define a pivot portion of a rotary joint together with, for example, a cranioplasty prosthesis or its components as described above. In this specification, it is generally referred to as a cranioplasty prosthesis element A. Therefore, the shoulder portion 115 can be defined as a pivot portion, a pivot part, a part of a rotary joint, a member, or a component. The rotary joint is a one-degree-of-freedom (DOF) rotary joint. In FIGS. 5 and 6, there may be some negligible play between the shoulder portion 115 and complementary connection components, as shown as the cranioplasty prosthesis element A among others. The cranioplasty prosthesis element A may be any cranioplasty prosthesis such as 10 or a part thereof. For example, it may be part of an attachment device 20, a skull fixation plate (also known as a fixation plate). Also, the shoulder portion 115 is also used as an abutment portion for controlling the penetration depth of the body portion 100 in the bone (for example, by an abutment segment described later). Further, the shoulder portion 115 cooperates with the cranioplasty prosthesis element A to ensure that the cranioplasty prosthesis element A can rotate in most situations. The shoulder portion 115 can prevent the pivot fastener F from interfering with the rotation of the cranioplasty prosthesis element A even when torque is applied by a tool when moving the pivot fastener F into the bone. The cranioplasty prosthesis element A is shown to have a hole A1 (FIG. 6), and the hole A1 can be, for example, any one of the connection holes 21A, 22A in FIG. 3.Furthermore, the skullplasty prosthesis element A may have a countersunk hole A2 for the hole A1. The usage of the countersunk hole A2 will be described later. As observed in FIG. 6, the countersunk hole A2 does not have a perfect cylindrical shape, and the countersunk hole A2 defined herein is a flat-bottomed hole having a generally circular cross-section that enlarges other coaxial holes A1.

[0047] Referring to FIGS. 5, 6, 9, and 10, the body portion 100 can be of the self-tapping screw type, but this is optional. For example, other screw types or rivet configurations may be used. The body portion 100 can have a shank 101 having a threaded portion and a tip 103 defined by one or more threads 102. As observed in FIG. 5, the shank 101 may optionally have a frustoconical shape having one or more frustoconical segments, but a cylindrical shank 101 is also conceivable. The tip 103 may have a conical shape. For example, the conical angle may be smaller than that of the frustoconical segment of the shank 101. Other configurations are possible. For example, a configuration having a shank 101 such as an overall conical shape or a straight shank is also possible. The threads 102 may be of different types. For example, they may be asymmetric (FIG. 9) or symmetric (FIG. 10). The dimensions and angles shown in FIGS. 9-10 are provided merely as examples. In one variant, the maximum diameter of the shank 101 is 1.50 mm ± 0.30 mm. However, this is merely given as an example. The maximum diameter of the shank 101 may be smaller, but it must be ensured that the threads 102 have appropriate strength for such purposes despite the small size. The maximum diameter of the shank 101 may be even larger. However, from the following description, it can be seen that it is preferable for the cross-section of the shank 101 to be smaller than that of the shoulder 115 in order for the shoulder 115 to prevent further entry. However, this is optional because there are other approaches to limit the depth of insertion of the body portion 100 into the bone. In one variant, both the shank 101 and the shoulder 115 have a circular cross-section, and the shoulder 115 has a diameter that is 1.00 mm ± 0.25 mm larger than the maximum diameter of the shank 101.

[0048] Referring to FIGS. 5-8, the head 110 is shown to have a relatively low profile, and the top surface 110A of the head 110 is, for example, frusto-spherical. However, other geometric shapes including a flat top surface 110A are also conceivable. The lower surface 110B of the head 110 may be flat, but is shown to have a tapered shape by being, among others, either frustoconical or frusto-spherical. By having the illustrated shape, the lower surface 110B tapers towards the shoulder 115. Such a taper towards the shoulder 115, as will be described later, may limit the contact surface between the lower surface 110B and the surface of the cranioplasty prosthesis element A. For example, as shown in FIG. 6, the head 110 may optionally be received within the countersunk hole A2 of the cranioplasty prosthesis element A (the cranioplasty prosthesis element A may have only the hole A1), and in such a case, the lower surface 110B may contact the surface of the countersunk hole A2. The presence of the taper for the lower surface 110B prevents complete surface contact between the head 110 and the cranioplasty prosthesis element A. This surface contact may increase friction and prevent rotation between the head 110 and the cranioplasty prosthesis element A. This contact between the head 110 and the prosthesis element A may be advantageous (edge) over surface contact.

[0049] The drive part 111 is shown as a cross slot. However, other shapes including a six - lobe shape, a slot shape, etc. are also possible. In one variant, in order to keep a low profile for the head 110, it may be more appropriate to have a recess - type drive part. As observed in FIG. 7, the corners of the slot may be rounded as a result of manufacturing, but this is optional. In one variant, the abutment surface 111A between the four tips of the cross may be given a specific shape or dimension so as to limit play using a screwdriver tool received within the drive part 111, for example, to define a frictional capture engagement part of the screwdriver tool within the drive part 111. For example, the abutment surface 111A may simultaneously be part of a virtual cylinder protruding upward from the circular bottom 111B of the recess of the drive part 111. The screwdriver tool may also be sized to have a complementary shape that fits tightly so as to limit or avoid slippage between the tool and the drive part 111. Further, such a complementary shape may contribute to maintaining the pivot fastener F at the end of the tool in a hands - free mode. Also in this case, since other drive part shapes including a six - lobe shape, a slot shape, etc. are possible, such features are optional.

[0050] Referring to FIGS. 5, 6, and 8, the shoulder 115 is shown to be more particularly between the body portion 100 and the head portion 110. Although the term "shoulder 115" is used, other names such as pivot, hub, abutment, shank, etc. may be used for the shoulder 115 for the following reasons observed based on the function of the shoulder 115. The fillet 115A may be the junction between the lower surface 110B of the head portion 110 and the shoulder 115, but the fillet 115A is optional. In one variation, the shoulder 115 can be divided into two segments, namely a pivot segment 116 and an abutment segment 117. In one variation, the pivot segment 116 has a substantially cylindrical shape. This cylindrical shape is optional because the pivot segment 116 can have other shapes such as, for example, a frustum of a cone. The shoulder 115 may also have a single segment, for example, the pivot segment 116, where the end face of the pivot segment 116 is flat, the body portion 100 projects from such a flat surface, and such a flat surface is the abutment end, and there may be a case where only the pivot segment 116 is present. The abutment segment 117, if it exists, has a frustum shape, and among them, it may have a frustum shape with a tapered shape (it may also be flat). Further, although the abutment segment 117 has a base with the same diameter as the pivot segment 116, other configurations are possible.

[0051] As observed in FIG. 6, the diameter of the pivot segment 116 is sized to be received with play within the hole A1 of the cranioplasty prosthesis element A. In other words, an annular gap may exist, defined between the circumferential surface of the hole A1 and the circumferential surface of the pivot segment 116. The circumferential surface of the pivot segment 116 may also be referred to as a bearing surface. Both the hole A1 and the pivot segment 116 are circular, and the cranioplasty prosthesis element A can rotate relative to the pivot fastener F about the axis H1. Accordingly, the radial dimensions of the hole A1 and the pivot segment 116 are selected to allow rotation. This may include providing the shoulder 115 with a height (i.e., a height along the axis H1) greater than the thickness of the element A at the connection hole A1. As another possibility, the distance or height (along H1) between the surface portion of the head 110B that contacts the surface of the implant A2 and the surface of the bone is greater than the thickness of the prosthesis element A, allowing rotation with limited friction.

[0052] Similarly, when there is a countersunk hole A2 and the head 110 has a circular shape as shown, an annular gap may exist, defined between the circumferential surface of the countersunk hole A2 and the circumferential edge of the head 110. In such an embodiment, since both the countersunk hole A2 and the head 110 are circular, these complementary features do not prevent the rotation of the cranioplasty prosthesis element A relative to the pivot fastener F about the axis H1. Accordingly, the radial dimensions of the countersunk hole A2 and the head 110 of the pivot segment are selected to allow rotation. When the expression "gap" is used to describe the relationship between the pivot segment 116 and the hole A1 and between the countersunk hole A2 and the head 110 of the pivot segment, it is to describe a sufficient clearance to allow rotation between the pivot fastener F and the prosthesis element A.

[0053] Further, it can be observed that the abutment segment 117 acts as an abutment portion that contacts the bone and resists the force for further entry of the pivot fastener F into the bone. Any frustoconical shape of the abutment segment 117 can counteract as a gradually strengthening (gradual) obstruction to the entry of the pivot fastener F into the bone. Any frustoconical shape of the abutment segment 117 can help to orient / align the insertion of the main body portion 100 while respecting the concentricity of the hole A and the surface 116. The abutment segment 117 in contact with the tapered surface A2 can help to ensure concentricity, but this is optional. In one variant, as observed in FIG. 8, the angle θ of the abutment segment is up to 45 degrees in total and greater than 0 degrees. However, there may be cases where the angle θ does not exist, i.e., the case where θ is equal to 0 degrees. The angle θ of the abutment segment can be described as a taper angle and can be defined as the angle between the plane orthogonal to the vector of the axis H1 (i.e., the central axis of the shoulder 115) and the tapered surface of the abutment segment 117.

[0054] The head 110 must have a larger cross-sectional feature than the shoulder 115 so that the head 110 prevents the axial displacement of the skull osteotomy prosthesis element A disengaged from the engagement with the shoulder 115. In one variant, both the head 110 and the shoulder 115 are circular, and the shoulder 115 has a diameter 0.90 mm ± 0.25 mm smaller than that of the head 110. Other configurations are also possible.

[0055] The overall length of the pivot fastener F may be varied. For example, its overall length can be at least 3.00 mm. Other lengths may be used, and there may be cases where the user selects the length as a function of the bone depth. When the pivot fastener F is used for other types of prostheses, its length may be substantially longer than 3.00 mm.

[0056] Referring to FIGS. 11A - 11C, an exemplary embodiment of the attachment device 120 is provided. The attachment device 120 may or may not be used with the pivot fastener F described herein. The attachment device 120 may or may not be part of the cranioplasty prosthesis 10. For example, the attachment device 120 may be used alone to attach the skull to the bone flap, to the prosthesis shell, or to a prosthesis different from the prosthesis blade 30. The attachment device 120 is designed to allow a constrained relative movement between the bone flap, the prosthesis shell, or the prosthesis covering the opening S and the skull surface around the opening S. The movement can be shown as being mostly out - of - plane, with a bidirectional residual movement of length L, and while the pivot fastener F may contribute to it herein, other types of fasteners may be used.

[0057] The attachment device 120 of FIGS. 11A - 11C is shown as having a planar body portion and can be made in a monoblock structure from a sheet material. For example, the attachment device 120 can be made from a single sheet material that can be cut by suitable methods such as laser cutting, CNC machining, casting, etc. For reference, the attachment device 120 can be present in a plane defined by the length L and the width W in the neutral position. The neutral position can be the natural state of the attachment device 120. The plane defined by the length L and the width W may be a flat surface, but may also have a curved state, i.e., a curved surface.

[0058] Similar to the attachment device 20 described above in connection with FIG. 3, the attachment device 120 may each have a first connection end 21 and a second connection end 22. For purposes of comparative explanation, similar reference numerals are shared between the attachment device 20 and the attachment device 120. The first connection end 21 is defined by a hole 21A configured to receive a pivot fastener, such as the pivot fastener F of FIG. 5, by way of example. In the attachment device 120, depending on the usage, there may or may not be rotation in the pivot fastener F. There may be more or fewer than the three holes 21A shown in FIGS. 11A - 11C. Also, the second connection end 22 optionally has a pair of (or more or fewer) holes 22A for receiving a pivot fastener that is the pivot fastener F of FIG. 5. In one embodiment, the holes 22A are aligned with each other along the width W. Other configurations are contemplated. In one variation, the holes 21A and / or the holes 22A have a circular shape as shown (e.g., a straight hole, a countersunk hole, a counterbored hole). Thus, the pivot fastener can be received within the hole 21A and / or 22A (whichever exists and whichever requires a pivoting motion), and the above-described rotational joint can be defined. Thus, the rotational joint enables a rotational motion indicated by R about a rotational axis that can be generally parallel to the height (perpendicular to the plane of FIGS. 11A - 11C). However, the rotational motion is optional and in some configurations there is no rotation.

[0059] The first connection end 21 and the second connection end 22 are interconnected by, for example, a coil portion 23 formed from a plurality of coils and by a frame portion 24. Further, the coil portion 23, which may also be referred to as a flyback mechanism, has a plurality of flyback portions. In use, the attachment device 120 each has the connection end 22 fixed to the skull S adjacent to the skull opening S1. The connection end 21 may be connected to a bone flap or prosthesis covering the skull opening S1, for example, to a prosthesis blade 30. Although a reverse arrangement is possible, it is not always appropriate. Although the connection end 21 is shown as having a hole for screwing into a component, the connection end 21 may be integrally connected to the blade portion 30 in a manner similar to that shown in FIG. 1.

[0060] The coil portion 23 is responsible for enabling out-of-plane movement of the second connection end 22 with respect to the first connection end 21 and with respect to the attachment device 120 in its neutral position (also referred to herein as the original state). The coil portion 23 is configured to restrict the movement of the first connection end 21 such that the first connection end 21 actually overlaps itself at height H. The rotational joint at the end 22 enabled by the pivot fastener can contribute to this pseudo-overlap. In other words, the coil portion 23 is arranged to limit the movement of the first connection end 21 along height H. While the first connection end 21 can also move along length L, when projected onto the neutral plane (i.e., in the original state), the change in distance along length L is substantially smaller than the change in distance along height H. On the other hand, the frame portion 24 is between the first connection end 21 and the coil portion 23. The frame portion 24 can optionally be a rigid component arranged on the curve (i.e., no in-plane deformation) and can be arranged on the curve so as to enforce the unidirectional deformation characteristic of the attachment device 20, i.e., to enable upward movement from the neutral state, as will be explained below. Thus, the movement of the first connection end 21 in the width W direction is restricted or negligible due to the physical restraint imposed by the frame portion 24. As can be observed, the coil portion 23 is connected to the frame portion 24, and the frame portion 24 enables various types of deformation of the coil portion 23. On the other hand, in one deformation example, the frame portion 24 can deform only by bending. Although this movement is described as that of the first connection end 21, a similar behavior may also apply to the second connection end 22 with respect to the first connection end 21. In one embodiment, during use, it is the second connection end 22 that leads when being slid into the incision. Although not essential, the flare shape leading towards the rear hole 22A from the front end and the rear position of the hole 22A with respect to the tip of the coil portion 23 in the direction L limit the movement in the H direction and further contribute to maintaining the attachment device 20 in a planar shape and to moving along the surface of the skull.The above flare shape from the front end towards the rear hole 22A, if it exists, may be expressed as an arc shape in some cases, or may have other shapes in other cases.

[0061] The coil portion 23 and the frame portion 24 have various components that restrict the relative movement of the end portions 21 and 22. The coil portion 23 has struts 23A that at least partially extend in the length L direction. The struts 23A can be interconnected by webs 23B. The webs 23B may be shorter than the struts 23A and may be disposed at the ends of the struts 23A. For example, the webs 23B may be in a direction transverse to the struts 23A and at least partially extend in the width W direction. Thus, when one of the end portions 21 and 22 receives a force, the web 23B deforms due to the lever effect of the strut 23A and allows out-of-plane movement of the strut 23A. The web 23B acts as a rotational joint (along W) due to the deformation. Although the struts 23A and the webs 23B are described as having different characteristics, the coil portion 23 may have curved sections that act as the struts 23A and the webs 23B, and the web 23B is at the junction with other struts 23A to which the curved section is connected. In this case as well, the struts 23A and the webs 23B can all be formed from a single sheet material. In one variant, the web 23B can be said to exhibit torsion when out-of-plane movement occurs for the strut 23A. Parallel to the torsion of the web 23B, the strut 23A can exhibit bending of the out-of-plane movement. In one variant, such torsion can be elastic deformation (although it can also be plastic deformation in some cases). When undergoing deformation, the attachment device 120 can be defined as a compliant mechanism, i.e., a flexible body that elastically deforms. Further, due to its configuration, the attachment device 120 can be said to be unidirectional in its displacement from its original state in that it can move only in one direction, i.e., towards the deformed state, from its original state (neutral plane). In its original state, the attachment device 120 cannot move in other directions through the normal forces and pressures during use. In other words, the attachment device 120 cannot deform in the negative H direction from the neutral plane / original state.This is because the frame portion 24 of the attachment device 120 is essentially in a direction crossing and above the kerf between the skull and the valve, and the attachment device 120 prevents the inward movement of the valve, i.e., the dent in the bone valve.

[0062] In contrast to the frame portion 24 of the attachment device 20 in FIG. 3, the frame portion 24 of the attachment device 120 in FIGS. 11A - 11C is shown to have a planar body portion 124A to which the coil portion 23 is connected at its end. The coil portion 23 can be said to be divided into two sets from the frame portion 24. The planar body portion 124A does not have a coil portion, and in contrast to the coil portion 23, the deformation of the frame portion 24 is restricted. The connection hole 124B can be at the junction between the two sets of the coil portion 23, and the connection hole 124B optionally receives a pivot fastener. It can be observed that there is an optional slot 124B' at the periphery of the connection hole 124B, and the connection hole 124B can have a break at its periphery. This slot 124B' or other dividing part enables the attachment device 120 to deform and conform to the shape of the bone at the connection hole 124B and / or at the junction between the coil portions 23. Also, from FIGS. 11B and 11C, it can be observed that additional slots 124B' can exist for the connection hole 124B. Additionally, the slot 124B' can form an additional switchback mechanism and thus can be said to be functionally hybridized. Similarly, the slot 124C can exist adjacent to the hole 21A, and again, this is for the purpose of enabling the attachment device 120 to conform to the geometric shape (i.e., 3D shape) of a bone, valve, etc., to which the connection end 21 is applied (when applicable). These slots 124B' and / or 124C can reduce the radiation - opaque footprint of the attachment device 120, thereby contributing to improved imaging. Further, the slots 124B' and / or 124C can reduce the weight of the metal material of the attachment device 120, which can have a positive impact on temperature control when imaging modalities such as MRI are used. The slot 124B' can exist without the slot 124C being present, and vice versa.If fasteners other than the pivot fastener F are used in some of the connection holes, the prosthesis may not be dynamic, and the coil portion may be prevented from deforming, thereby giving the plate the possibility of acting as a rigid plate.

[0063] Referring to FIGS. 11B and 11C, a cutout 124D may be present in the planar body portion 124A, which can be seen through imaging and which can be observed to provide a user guidance portion. For example, the cutout 124D is in the form of an arrow in FIGS. 11B and 11C and can indicate, for example, the direction of insertion of the attachment device 120. For different reasons, other forms of markings (e.g., letters, numbers) may be defined by the cutout 124D. For example, the cutout 124D can indicate size, orientation (e.g., indicating that the surface of the planar body portion 124A should face away from the skull), etc. The cutout 124D may be present with the slots 124B' and / or 124C or may be present without them.

[0064] Another type of cutout 124E can be used to suggest the location of a kerf or other anatomical mark. For example, FIG. 11A shows a target-shaped geometry where a plurality of cutouts 124E end at a virtual line W1, while FIG. 11B shows a series of points along such a line W1. Other geometries and shapes are possible. The cutout 124E may or may not be present with the slots 124B' and / or 124C and / or the cutout 124D.

[0065] In FIGS. 12 and 13, another embodiment of the attachment device is shown as 130. The attachment device 130 is of a type that can be used in other types of orthopedic procedures such as bone lengthening in distraction osteogenesis, for example. The attachment device 130 may or may not be used with the pivot fastener F described herein. The attachment device 130 is designed, for example, to allow constrained relative movement between two bone segments. The movement can be shown as being along a length L, and while the pivot fastener F described herein may contribute to it, other types of fasteners may also be used.

[0066] The attachment device 130 is shown as having a planar body portion and can be made from a sheet material in a monoblock structure. For example, the attachment device 130 can be made from a single sheet material that can be cut by suitable methods such as laser cutting, CNC machining, casting, etc. For reference, the attachment device 130 can be present in a plane defined by a length L and a width W in the neutral position. The neutral position can be the natural state of the attachment device 130. The plane defined by the length L and the width W may be a flat surface, but may also have a curved state, i.e., a curved surface. As observed in FIG. 12, it can be formed to conform to the shape of the bone, herein for example the shape of the femur.

[0067] Similar to the attachment device 20 described above in connection with FIG. 3, the attachment device 130 may have a first connection end 21 and a second connection end 22. For purposes of comparative explanation, similar reference numerals are shared between the attachment device 20 and the attachment device 120. The first connection end 21 is defined by a hole 21A configured to receive a pivot fastener, such as the pivot fastener F of FIG. 5, for example. There may be more or fewer than two holes 21A shown in FIGS. 12 - 13. Also, the second connection end 22 optionally has a pair of (or more or fewer) holes 22A for receiving a pivot fastener, which is the pivot fastener F of FIG. 5, thereby forming a rotational joint (i.e., a one - rotational DOF joint). In one embodiment, the holes 22A are aligned with each other along the width W. Other configurations are conceivable. In one variant, the holes 21A and / or the holes 22A have a circular shape (e.g., a straight hole, a countersunk hole, a counterbored hole) as shown. Thus, the pivot fastener can be received within the hole 21A and / or 22A (whichever exists and whichever requires pivoting motion), and can define the rotational joint described above. Thus, the rotational joint can enable a rotational movement indicated by R about a rotational axis that can be generally parallel to the height (perpendicular to the plane of FIGS. 12 - 13).

[0068] The first connection end 21 and the second connection end 22 are interconnected by a coil portion 23 formed, for example, from a plurality of coils and by a frame portion 24. Also, the coil portion 23, which may also be referred to as a switchback mechanism, has a plurality of switchback portions. This switchback mechanism enables the rotational movement described later, and due to this rotational movement, longitudinal expansion of the attachment device 130 described later becomes possible. In contrast to other embodiments, with fewer coils in the attachment device 130, only expansion can be caused, and out - of - plane movement cannot be caused.

[0069] The coil portion 23 is responsible for enabling in-plane expansion and / or contraction movement of the second connection end 22 with respect to the first connection end 21, and in-plane expansion and / or contraction movement with respect to the attachment device 130 in its neutral position (also referred to herein as the original state). The coil portion 23 is configured to constrain the movement of the first connection end 21 such that the first connection end 21 can move along the length L. The rotational joint enabled by the pivot fastener at the end 22 can contribute to this lengthwise expansion. The frame portion 24 is between the first connection end 21 and the coil portion 23. The frame portion 24 is a rigid component (i.e., no in-plane deformation), and optionally, is disposed on a dividing line (e.g., a kerf) between two bone segments, interconnecting the bone segments while enabling expansion or contraction movement between them and preventing or restricting other movements, and can be a rigid component. In other uses, the frame portion 24 and its lack of in-plane deformation can optionally be disposed on the bone end line for the orthopedic purpose of controlling or restricting unwanted growth (not only for fractured bones). Thus, the movement of the first connection end 21 in the width W direction is restricted or negligible due to the physical constraints imposed by the frame portion 24. As can be observed, the coil portion 23 is connected to the frame portion 24, and the frame portion 24 enables various types of deformation of the coil portion 23. On the other hand, in one variant, the frame portion 24 can only deform by bending. Although its movement is described as that of the first connection end 21, similar behavior may be applicable to the second connection end 21 from the perspective of the first connection end 21.

[0070] The coil portion 23 and the frame portion 24 constrain the relative movement of the end portions 21 and 22 by having various components. Another function enabled by the coil portion 23, in a particular configuration (e.g., as shown in FIG. 13), is that the overall in-plane displacement can be restricted by the interaction of two or more webs / struts that effectively (and predictably) collide and can prevent additional movement in the form of a stopper. The coil portion 23 has struts 23A that at least partially extend in the length L direction. The struts 23A can be interconnected by webs 23B. The webs 23B may be shorter than the struts 23A and may be disposed at the ends of the struts 23A. For example, the webs 23B may be in a direction transverse to the struts 23A and at least partially extend in the width W direction. Thus, when one of the end portions 21 and 22 receives a force, the web 23B deforms due to the lever effect of the strut 23A and allows out-of-plane movement of the strut 23A. The web 23B acts as a rotational joint (along W) due to the deformation. Although the struts 23A and the webs 23B are described as having different characteristics, the coil portion 23 may have curved sections that act as struts 23A and webs 23B, and the web 23B is at the junction with other struts 23A to which the curved section is connected. In this case too, the struts 23A and the webs 23B can all be formed from a single sheet material. In one variant, the web 23B may be said to exhibit torsion when out-of-plane movement occurs for the strut 23A. Parallel to the torsion of the web 23B, the strut 23A may exhibit bending of the out-of-plane movement. In one variant, such torsion can be elastic deformation (although it may also be plastic deformation). When undergoing deformation, the attachment device 130 can be defined as a compliant mechanism, i.e., a flexible body portion that elastically deforms.Furthermore, due to its configuration, the attachment device 130 can be said to be unidirectional in its displacement from its original state in that it can move from its original state (neutral plane) in only one direction, i.e., towards the deformed state. In its original state, the attachment device 130 cannot move in other directions through normal forces and pressures during use. In other words, the attachment device 130 cannot deform in the negative H direction from the neutral plane / original state. This is because the frame portion 24 of the attachment device 130 is essentially in a direction transverse to and above the dividing line between the bone segments, and the attachment device 130 prevents the inward movement of the bone segments.

[0071] In contrast to the frame portion 24 of the attachment device 20 in FIG. 3, the frame portion 24 is shown as a straight and elongated portion. The coil portion 23 can be said to be divided from the frame portion 24 into two sets of coils. The frame portion 24 does not have a coil portion, and in contrast to the coil portion 23, the deformation of the frame portion 24 is limited. The frame portion 24 has a straight and elongated shape, although other shapes are conceivable. The illustrated elongated shape of the frame portion 24 is particularly well-suited for application to long bones, for example, along the diaphysis of long bones.

[0072] Accordingly, the foregoing describes an assembly, the assembly comprising a skullplasty prosthesis element having at least one connection hole, and a pivot fastener having a threaded body portion adapted to be screwed into the skull, a head having a driving member, and a shoulder between the body portion and the head, the shoulder having a circular section, the radial dimension of the circular section being smaller than the radial dimension of the connection hole, and the shoulder forming a rotary joint with the skullplasty element when the shoulder is within the connection hole. Further, this application describes the use of pivot fastener F with a skullplasty prosthesis, but pivot fastener F may also be used with other types of implants, in particular with implants that need to be fixed to bone and may require rotational movement. Implants and prostheses used in orthopedic surgery may be used with one or more pivot fasteners F.

[0073] Accordingly, the present disclosure may relate to an assembly comprising a prosthesis element having at least one connection hole, and a pivot fastener having a body portion adapted to be received within the skull, a head, and a shoulder between the body portion and the head, the shoulder having a circular section, the radial dimension of the circular section being smaller than the radial dimension of the connection hole, and the shoulder forming a rotary joint with the prosthesis element when the shoulder is within the connection hole.

[0074] The above description is merely illustrative, and those skilled in the art will understand that modifications can be made to the described embodiments without departing from the scope of the disclosed invention. The cone portion (e.g., frustum portion) described in this specification is for a right circular cone. Further modifications that fall within the scope of the present invention will be apparent to those skilled in the art in light of the present disclosure. Moreover, such modifications are intended to be within the scope of the appended claims.

Claims

**Claim 1** An assembly, the assembly comprising: a prosthesis element having at least one connection hole; and a pivot fastener, the pivot fastener comprising: a body portion adapted to be received within bone, a head, and a shoulder between the body portion and the head, the shoulder having a circular section, wherein a radial dimension of the circular section is smaller than a radial dimension of the connection hole, and the shoulder forms a rotational joint with the prosthesis element when the shoulder is within the connection hole. **Claim 2** The assembly according to claim 1, wherein the shoulder has a pivot segment adjacent to the head and an abutment portion adjacent to the body portion. **Claim 3** The assembly according to claim 2, wherein the pivot segment has a cylindrical shape. **Claim 4** The assembly according to claim 2 or 3, wherein the abutment portion is an abutment segment. **Claim 5** The assembly according to claim 4, wherein the abutment segment has a tapered shape that tapers towards the body portion. **Claim 6** The assembly according to claim 5, wherein a diameter of a base of the tapered shape is equal to a diameter of the pivot segment at a junction between the base and the pivot segment. **Claim 7** The assembly according to claim 4 or 5, wherein the tapered shape is a frustum of a cone. **Claim 8** The assembly according to claim 7, wherein the abutment segment has a taper angle of up to 45 degrees in total and greater than 0 degrees. **Claim 9** The assembly according to claim 4 or 5, wherein the tapered shape is a truncated sphere. **Claim 10** The assembly according to any one of claims 1 to 9, wherein the head has a diameter greater than a maximum diameter of the shoulder, and the head is received within a countersunk hole of the connection hole of the prosthesis element. **Claim 11** The assembly according to claim 10, wherein a lower surface of the head has a tapered shape that tapers towards the shoulder. **Claim 12** The assembly according to any one of claims 1 to 11, wherein the body portion has a frustum-shaped shank portion that supports at least one thread. **Claim 13** The assembly according to claim 12, wherein the shoulder has a diameter that is 1.00 mm ± 0.25 mm larger than the maximum diameter of the shank.

14. The assembly according to claim 13, wherein the body portion has a conical tip.

15. The assembly according to any one of claims 1 to 14, wherein the body portion has a thread and the head has a drive portion.

16. The prosthesis element is an attachment device having a body portion defined from a sheet material, and a first connection end, the first connection end having at least one of the connection holes, the at least one of the connection holes being configured to cooperate with one of the pivot fasteners to fix the attachment device to a bone flap or prosthesis covering at least a part of an opening in the skull; a first connection end; a second connection end, the second connection end having at least one other of the connection holes, the at least one other of the connection holes being configured to cooperate with another one of the pivot fasteners to fix the attachment device adjacent to the opening in the skull; a second connection end; a frame portion extending from the first connection end; a coil portion between the frame portion and the second connection end, the coil portion having struts configured to deform by bending and webs between the struts configured to deform by torsion; a coil portion; the frame portion is disposed on the periphery of the opening in the skull and is configured to prevent inward movement, and the coil portion enables out-of-plane deformation of the attachment device with respect to the first connection end such that the coil portion moves outward of the neutral plane together with the second connection end. The assembly according to any one of claims 1 to 15.

17. The assembly according to claim 16, wherein the body portion extends in the longitudinal direction from the first connection end to the second connection end, and at least some of the struts extend at least partially in the longitudinal direction.

18. The prosthesis element is an attachment device having a body portion defined from a sheet material, and A first connection end having at least one hole configured to receive a fastener to secure the attachment device to a first bone portion, A second connection end having at least one of the connection holes configured to cooperate with one of the pivot fasteners to secure the attachment device to a second bone portion, A frame portion extending from the first connection end, A coil portion between the frame portion and the second connection end, the coil portion having struts configured to deform by bending and webs between the struts configured to deform by torsion, The frame portion is configured to be disposed on a separation line or bone end line between the first bone portion and the second bone portion, and The coil portion enables deformation of the attachment device about the first connection end such that the coil portion expands in a plane. The assembly according to any one of claims 1 to 15. **Claim 19** The assembly according to claim 18, wherein the frame portion is a straight segment. **Claim 20** The assembly according to claim 18 or 19, wherein the at least one hole in the first connection end is at least one of the connection holes configured to cooperate with one of the pivot fasteners.

Images