Device comprising a composite material

Abstract

A device (500), the device comprising a compressed body portion (502) comprising one or more layers of a fiber reinforced composite material; wherein the body portion (502) is substantially planar, having opposing first and second face surfaces (505, 507) and a peripheral edge profile (510) defined between the first and second face surfaces. The body portion (502) includes a plurality of apertures (504) passing between the face surfaces. The peripheral edge (510) is non-linear between adjacent holes (504) and is formed by cutting or machining. A related manufacturing method of the device (500) is also disclosed.

Description

[0001] The present invention relates to a device comprising a compression moulded body portion comprising a layer of fibre reinforced composite material and a method of manufacturing such a device. Background Art

[0002] Composite materials comprising polymers and reinforcing fibers are known. Examples of such composite materials include carbon fibers and polyaryletherketone (PAEK). For example, a composite material includes carbon fibers and polyetheretherketone (PEEK).

[0003] Such composite materials can be used in a variety of applications, including, for example, in the manufacture of medical devices. For example, such composite materials can be used to manufacture implantable devices, such as orthopedic implants; in particular, implantable devices in the form of fracture fixation plates or deformity correction plates, collectively referred to herein as bone plates.

[0004] Bone plates can be used in surgical procedures to fix bone fragments together and realign bones and their fragments. Bone plates typically include preformed holes therethrough for receiving fixation screws that attach the plate to the bone. An example of a known bone plate is shown in FIG. 1 . Bone plate 100 includes a generally longitudinal body 102 having a plurality of holes 104 formed therethrough from an upper surface 105 to a lower surface (not shown). Holes 104 may be circular or in the form of slots 104'. Holes 104, 104' may be chamfered at upper surface 105 to better receive associated screws for a flush fit.

[0005] Such bone plates are typically formed from surgical grade stainless steel or titanium. More recently, fiber reinforced composite materials such as carbon reinforced polyetheretherketone (PEEK) have been used to form bone plates. One way to form such composite plates is by laying down layers (or plies) of composite tape having carbon fibers with different orientations in the XY directions into a mold in the Z direction. An illustration of such a ply is shown in FIG. Fig.10 See Fig.10 , which is a schematic diagram of an exemplary layup arrangement of layers of tapes formed from a composite material. Starting from the bottom of the layup as shown, the first layer is formed of tapes aligned unidirectionally along an axis (0°). The second layer is formed of tapes aligned unidirectionally at 45° to the axis of the first layer. The third layer is formed of tapes aligned unidirectionally at -45° to the axis of the first layer. The fourth layer is formed of tapes aligned unidirectionally at 90° to the axis of the first layer. The pattern is repeated so that the overall structure has the following alignment angles: 0°, 45°, -45°, 90°, -45°, 45°, and 0. The resulting laminate can be compression molded under heat and pressure to form a semi-finished part - a blank. Additional features, such as holes for receiving screws, k-wires, or sutures, can then be machined into the blank to form a finished plate. The axis of the screw hole is typically parallel to the Z direction but no greater than ±45 degrees relative to the Z direction. This type of composite plate typically has straight parallel sides, such as Fig. 9 shown.

[0006] It is known that providing a metal bone plate with a shaped edge between adjacent holes in the plate by removing material is called scalloping. This provides both aesthetic and clinical benefits. For example, by removing material from the edge between adjacent holes, the plate can be made lighter, narrower and more streamlined than a straight edged article. Scalloping between the holes can also provide space in which screws or other fixings (suture buttons) adjacent to the plate in the groove are received. An example is shown in FIG. 14 , in which a bone plate 200 is fixed to the fibula and tibia by screws 250 and suture buttons 252, one of which is received in a grooved area adjacent to the bone plate 200. Additionally, scalloping between the holes enables bending of the metal plate during surgery without affecting the geometry of the screw holes, so the surgeon can contour the metal plate to better fit the bone.

[0007] exist Fig. 9 No grooves are formed in the straight sides of composite panels of the type shown in , as it is believed that to do so would compromise the strength of the component due to the need to machine the grooves into the blank, thereby necessarily shearing the reinforcing fibers therein.

[0008] Another way to form a composite plate is by using a composite flow forming technique which allows for the formation of non-linear edges and can provide similar benefits to the groove process outlined above. An example of such a plate is a "serpentine plate" 300, such as Fig.12 and FIG. 13. Composite flow forming of such a plate involves randomly placing relatively small chopped portions of pre-impregnated fiber reinforced composite materials (such as carbon reinforced polyetheretherketone (PEEK)) into a mold (not shown) having the shape of the desired finished plate. The chopped portions are typically square or rectangular blocks of about 1 cm to 2 cm. In the case where holes 304 are provided in the finished plate 300, the mold will include corresponding columns, and the chopped portions will be laid around these columns. The mold is therefore filled with random chopped pieces, the mold is closed, and then heated so that the PEEK matrix melts. The mold is then further compacted to expel any remaining air and consolidate the material in the mold. In the process, the material flows around the contour of the mold, and the fibers 308 in the material therefore flow around the columns to form holes 304 and align with the external shape of the plate 300. This can be seen in the detailed view of FIG. 13. Summary of the invention

[0009] According to a first aspect of the invention, there is provided an apparatus comprising a compression molded body portion comprising one or more layers of a fiber reinforced composite material; wherein the body portion is substantially planar, having opposing first and second face surfaces and a peripheral edge profile defined between the first and second face surfaces, and the body portion comprises a plurality of holes passing between the face surfaces; wherein the peripheral edge is nonlinear between adjacent holes; and wherein the peripheral edge is formed by cutting or machining. The faces may be upper and lower surfaces.

[0010] Forming the peripheral edge by cutting or machining allows providing a groove edge for the fiber reinforced composite device without using compression flow forming technology and chopping prepreg blocks, so that the integrity of most of the fibers in the entire finished device can be maintained over its full length. In addition, because the device is compression molded, the configuration of the constituent plies can be precisely controlled compared to composite flow forming technology, in which the orientation of relatively small reinforcing fibers is difficult to control throughout the molding process and is therefore inconsistent in the resulting device. Surprisingly, it has been found that cutting or machining to form the peripheral edge does not substantially affect the strength of the finished part.

[0011] The body may be elongated with a longitudinal axis extending between opposite first and second ends of the body and opposite first and second sides extending in the longitudinal direction and forming at least a portion of the peripheral edge. The first and second sides may be substantially parallel to each other. At least one of the holes may be disposed on the longitudinal axis. The body portion may be substantially symmetrical about the longitudinal axis.

[0012] In an embodiment where the body has a longitudinal axis and opposing first and second sides extending in the longitudinal direction and forming at least a portion of the peripheral edge, the peripheral edge may have a maximum lateral width between the opposing first and second sides in line with each of the holes and a minimum lateral width between the opposing first and second sides in a region between adjacent holes. The minimum lateral width may be midway between adjacent holes. The ratio of the maximum lateral width to the minimum lateral width may be in the range of 1.1 to 1.4, preferably in the range of 1.15 to 1.3.

[0013] The peripheral edge may be concave between adjacent apertures.The peripheral edge may have a complex curvature adjacent each aperture, wherein a convex curvature concentric with each said aperture transitions to a concave curvature between the apertures.

[0014] According to some embodiments, the minimum amount of material between each hole and the associated peripheral edge is less than 3 mm, such as 2 mm, or less than 1 mm, or less than 0.5 mm.

[0015] The compression molded body portion may include layers of composite material, which may include reinforcing fibers formed into continuous filaments. The continuous filaments in one layer may be positioned at an angle to the continuous filaments in an adjacent layer.

[0016] The composite material may include a polyaryletherketone, which may be polyetheretherketone (PEEK), and the reinforcing fibers may be carbon fibers.

[0017] According to certain embodiments, the device is an implantable medical device, which may be a bone plate.

[0018] According to a second aspect of the present invention, a method for manufacturing a device is provided. The method comprises: laying one or more layers of a fiber reinforced composite material into a compression mold; pressing the one or more layers of the composite material together to form a substantially planar main body portion of the device, the main body portion having opposite upper and lower surfaces and a peripheral edge profile defined between the upper and lower surfaces; machining the main body portion to form a plurality of holes passing therethrough between the upper and lower surfaces; and machining the peripheral edge profile between adjacent holes into a nonlinear profile. Thus, this construction method comprises: first forming a blank having substantially straight sides by laying plies of fiber reinforced composite material substantially the size of the mold and pressing them together in the mold, and then performing a machining process on the blank to form through-holes and groove edge profiles. Due to the simple shape of the mold and the fact that the plies also have a correspondingly simple shape and are easy to lay in the mold, the initial compression molding of the blank is simple. The machining process of the hole and groove portions is also simple. Thus, a strong, beautiful and practical device can be manufactured quickly and efficiently.

[0019] According to a third aspect of the present invention, another method for manufacturing a device is provided. The method includes: laying one or more layers of a fiber reinforced composite material into a compression mold, wherein each layer has at least one nonlinear side edge; pressing the one or more layers of the composite material together to form a substantially planar body portion of the device, the body portion having a first face and a second face (e.g., an upper surface and a lower surface) opposite each other and a nonlinear peripheral edge profile defined between the first face and the second face and defined by at least one nonlinear side edge; and machining the body portion to form a plurality of holes passing therethrough between the upper surface and the lower surface, so that at least a portion of the peripheral edge profile between adjacent holes is nonlinear. Therefore, this alternative construction method includes: first forming a ply by cutting or punching a layer of a fiber reinforced composite material into a shape corresponding to the shape of the mold and defining the necessary nonlinear peripheral edge profile, laying plies of a fiber reinforced composite material substantially the size of the mold and pressing them together in the mold into a blank having a groove edge, and then performing a machining process on the blank to form a through hole. Due to the simple shape of the mould and the fact that the plies also have a correspondingly simple shape and are easy to lay in the mould, the initial compression moulding of the blank is simple, although there is a preliminary step of cutting the edges of the grooves into the plies. The machining process of the holes is likewise simple. Thus, a strong, aesthetic and functional device can be manufactured quickly and efficiently.

[0020] Advantageously, manufacturing a panel using this compression molding technique according to the second or third aspect described herein allows precise control of the orientation of the fibers within the finished product, thereby ensuring that the fiber direction is consistent and reliable. This means that the desired mechanical properties can be achieved by appropriately selecting and orienting the constituent plies within the mold.

[0021] The method as defined in the second aspect or the third aspect of the invention may be a method of manufacturing the device according to the first aspect of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Embodiments of the present invention are further described below with reference to the accompanying drawings, in which:

[0023] FIG. 1 is a top plan view of a bone plate known from the prior art;

[0024] Figure 2 is a bottom perspective view of a grooved bone plate according to one embodiment;

[0025] Figure 3 yes Figure 2 A top plan view of the bone plate;

[0026] Figure 4 is a schematic top plan view of a bone plate according to an embodiment prior to a groove machining operation;

[0027] Figure 5 Yes Figure 4 a detailed view of one end of the depicted bone plate;

[0028] Figure 6 and Figure 5 A corresponding but machined groove portion;

[0029] Figure 7 is a top plan view of a bone plate having a relatively deep recessed portion according to one embodiment;

[0030] Figure 8 is a top plan view of a bone plate having a relatively shallow recessed portion according to another embodiment;

[0031] Fig. 9 is with Figure 7 or Figure 8 A top plan view of a reference bone plate corresponding to the base reference bone plate but without the groove portion;

[0032] Fig.10 is a schematic diagram of a ply arrangement that may be used to manufacture the device by compression molding;

[0033] Figures 11a to 11d depicts bone plates of various sizes and configurations according to various embodiments;

[0034] Fig.12 Depicts the known alternative "snake plate" type of bone plate;

[0035] FIG. 13 depicts a composite flow forming process. Fig.12 the arrangement of fibers within the composite material of the panel; and

[0036] FIG. 14 depicts a known bone plate for fixation of an ankle joint. DETAILED DESCRIPTION

[0037] See this article Figures 2 to 8 , Fig.1011 and 12 describe a device 500 (particularly a bone plate) in the form of an implantable medical device and an associated method of manufacturing the same according to an embodiment. The bone plate 500 includes a body portion 502 that is substantially planar, has a first surface 505 and a second surface 507, and a peripheral edge profile 510 defined between the first surface and the second surface. In this example, the bone plate 500 is elongated and has a longitudinal axis extending between its opposite first end 501 and second end 503. Opposite first sides 512 and second sides 514 extend in the longitudinal direction and form at least a portion of the peripheral edge 510, continuously connected to the portions at the first end 501 and the second end 503. A plurality of holes 504 in the form of circular holes 504 or slot holes 504' pass between the upper surface 505 and the lower surface 507. The peripheral edge 510 is concave, i.e., non-linear, between adjacent holes 504, 504'.

[0038] exist Figures 2 to 4 , Figure 7 and Figure 8 In the specific example of FIG. 5 , the bone plate includes two circular holes 504 at the first end 501 and three circular holes 504 at the second end 503. The slotted hole 504' is located between the two sets of circular holes 504, toward the first end 501. The central portion 516 is disposed between the slotted hole 504' and the set of three circular holes 504 at the second end 503. However, other configurations of holes are contemplated. For example, Figures 11a to 11d As depicted, shorter plates may generally have fewer holes; conversely, longer plates may include more holes. In all illustrated examples, the holes are arranged on the longitudinal axis of the plate, and the plate is substantially symmetrical about the longitudinal axis, but this is not necessarily the case. It should be understood that any suitable hole configuration may be used, keeping in mind that more holes provide the surgeon with more fixation points to use, but a larger number of holes may also affect structural integrity if they are arranged too closely.

[0039] Each circular hole 504 has a first radius 530. The slotted hole 504' has a lateral width 532 perpendicular to the longitudinal axis, which can be the same size as the first radius 530, as illustrated, or can take a different size. For purposes described below, each hole can have a chamfer 540 around its opening at the upper surface 505 and optionally at the lower surface 507.

[0040] The peripheral edge 510 includes a first portion 510a corresponding to the first side 512 and a second portion 510b corresponding to the second side 514. In the illustrated embodiment, those first and second portions 510a, 510b of the peripheral edge are symmetrical, so the description of the first portion 510a also covers the fourth portion 510d. The central region of the first portion 510a adjacent to the central body portion 516 and between the innermost holes 504, 504' is concave, defined by a concave curve 531 of radius R. Proceeding toward the second end 503, the next region of the first portion 510a is also concave, defined by a composite curve including a convex curve 534 surrounding and concentric with each hole 504, which smoothly transitions to a concave curve 536 of radius r centered between the respective adjacent holes 504. Likewise, proceeding toward the first end 501, the next zone of the first portion 510a is concave, defined by a compound curve comprising a convex curve 534 around and concentric with each aperture 504', 504', which smoothly transitions to a concave curve 536 centered between respective adjacent apertures 504, 504', with the only difference being that the convex curve 534 around the slot aperture 504' is concentric with the circle defining one end of the slot. At the first end 501 and the second end 503, the convex curve 534 around the respective outermost aperture 504 continues around each of said apertures, thereby forming respective third and fourth portions 510c, 510d of the peripheral edge to continuously connect the first and second portions 510a, 510b thereof at each end. It will be appreciated that this is not required and is merely a convenient and aesthetically pleasing way of forming the peripheral edge profile at the respective ends of the device; a different curve or straight edge may be used instead.

[0041] The lateral width of the plate 500 is defined as perpendicular to the longitudinal direction. The maximum lateral width W is defined by the diameter of the convex curve 534 and is in line with each associated hole 504. The minimum lateral width w is defined in the area between the corresponding adjacent holes, usually at the midpoint. Usually, the width at the midpoint of the center portion 516 will be equal to the minimum width w defined between adjacent holes. Because the distance between the innermost holes 504, 504' is greater than the distance between the adjacent holes in the group at each end 501, 503, the associated radius R is greater than the radius r.

[0042] The depth of the groove treatment of the peripheral edge 510 can vary according to design intent. Figure 7 An embodiment with relatively deep groove processing is illustrated in FIG. D and Figure 3 Therefore, common parts use common reference numerals; different parts are followed by suffixes. D To represent this deep groove embodiment. Figure 7 A side view of the plate is also included to show its depth D and depict its length L from the first end 501 to the second end. Figure 8 Another embodiment is shown, this time a plate 500 having a relatively shallow groove treatment. S Here again, we use the combination Figure 3 The reference numerals used are followed by the suffix S To illustrate the different aspects of this shallow groove embodiment. As shown in the figure, and for ease of comparison, the plate 500 D , 500 S Use the same overall dimensions, i.e. the same depth D, length L and maximum lateral width W D and W S It should be understood that in certain embodiments, the dimensions may be different.

[0043] Fig. 9 Depicted reference plate 500 R , the reference board has a 500 D , 500 S Same overall dimensions, ie same depth D, length L and maximum lateral width W.

[0044] exist Figure 7 In the implementation scheme, the minimum width w D (in mm) is the radius r of the concave curve 536 centered between respective adjacent holes 504 (and between the slotted hole 504' and the adjacent circular hole 504 towards the first end 501). D The radius R of the concave curve 531 between the innermost holes 504, 504' at the central body portion 516 is approximately twice. D Yes D Approximately four times (in mm) of

[0045] exist Figure 8 In order to achieve this profile, the radius r of the concave curve 536 located between the corresponding adjacent holes 504 (and between the narrow slot hole 504' and the adjacent circular hole 504 toward the first end 501) is S The radius R of the concave curve 531 between the innermost holes 504, 504' at the central body portion 516 is approximately S One sixth of .

[0046] Thus, the ratio of the maximum lateral width W to the minimum lateral width w is in the range of about 1.1 to 1.4, preferably in the range of 1.15 to 1.3. To ensure structural integrity, a minimum amount of material is provided between each hole 504, 504' and the associated peripheral edge 510. This minimum dimension will depend on factors including the material used to make the plate and the depth D of the plate. In the illustrated example, this minimum dimension is about 2.00 mm.

[0047] The bone plate 500 according to the present invention is compression molded and includes layers of a fiber reinforced composite material. Typically, the composite material comprises carbon fibers and polyaryletherketone (PAEK), more specifically polyetheretherketone (PEEK). As described in the introduction and with reference to Fig. 9 As mentioned above, it is known to produce straight side bone plates using this manufacturing method.

[0048] To manufacture the bone plate 500 having a grooved edge profile, the first step is to produce a straight-sided blank in a known manner, as shown in FIG. Fig.10 As described above, composite tape layers (or plies) with carbon fibers having different orientations in the XY directions are laid in the Z direction into a mold. Composite prepreg tapes formed of PEEK polymer and continuous carbon fibers are laminated into a blank. The plies can be laid in alternating layers, wherein the reinforcing fibers extend alternately in the longitudinal direction and transverse to the longitudinal direction. Through holes 504, 504' are then machined into the blank. This is Figure 4 1000, where continuous filaments of reinforcing fibers 1008 are shown extending along the length of the blank 1000. Intermediate layers at other orientations, such as 45 degrees, are also possible.

[0049] Next, the groove portion is formed by machining. A schematic detail of the machining step is shown in FIG. Figure 5 As shown in FIG. 1 , a groove portion is formed between adjacent circular holes 504 to form a groove having a radius r. D The concave curve 536 of radius W / 2 and the corresponding, continuous convex curve 534 of radius W / 2. Figure 6 Further similar machining between other adjacent holes 504, 504' completes the formation of the groove peripheral edge 510. The groove portion may alternatively be machined before or simultaneously with the machining of the holes.

[0050] In particular, if Figure 6As schematically seen in FIG, machining of the grooved portion results in discontinuities in the reinforcing fibers 1008 in the machined area. Specifically, at least some of the continuous filaments 1008 near the outer sides 512, 514 extending in the longitudinal direction are cut. While, in theory, it may be expected that discontinuities in the reinforcing fibers 1008 would be detrimental to the material properties of the finished panel 500, since the contribution of those fibers may be relatively limited, surprisingly, it has been found that the material properties are only slightly affected by the groove process. In practice, Figure 7 , Figure 8 and Fig. 9 Bending strength tests performed on an exemplary panel of Fig. 9 Straight side reference plate 500 R compared to, Figure 7 Deep groove plate 500 D The bending strength is reduced by 11%. Fig. 9 Reference board 500 R test Figure 8 The plate 500 having a shallow groove portion S It performed 11% better.

[0051] In an alternative manufacturing method, rather than laying up a straight-sided mold with straight-sided plies of similar shape, forming a blank and then machining the groove profile, the initial plies can be pre-cut to include groove edges corresponding to the desired final shape, and these groove edges can be laid into a mold with the groove shape. After compression molding, the resulting blank will already have the desired groove profile, so post-molding machining of the edges will not be required. Some minor machining may still be required to trim the resulting board after molding, but to a much lesser extent than would be required to machine all of the groove portions.

[0052] In use, fixings such as screws or suture buttons and other plate parts, for example, can be inserted into the groove area adjacent to the plate 500, thereby providing more available positions for the surgeon. In addition, the groove shape is more aesthetically pleasing and more easily accepted by surgeons and patients, just like the well-known metal plates.

[0053] Chamfers 540 around the holes 504, 504' allow the fastener to fit flush with the upper surface 505 when inserted through the corresponding hole.

[0054] The composite material may be provided in the form of a tape. A layer (also referred to as a "ply") may be formed from joined portions of the tape. The composite material may take the form of a web or other precursor that may be used to form a compression molded body portion of a desired shape and / or configuration.

[0055] The device may be a medical device, such as an implantable device. Examples of implantable devices include orthopedic implants, such as fracture plates, trauma plates, spinal implants, and other load-bearing implantable devices.

[0056] The composite material may additionally include additives in the matrix. Examples of additives include bioactive agents (such as hydroxyapatite) or image contrast agents (such as barium sulfate). In some examples, the composite material may include an image contrast agent. The image contrast agent may be present in all layers of the composite material or in selected layers. The contrast agent may be a material that can be detected by X-rays. For example, the contrast agent may be barium sulfate.

[0057] Polyaryletherketone

[0058] Any suitable PAEK may be used in the composite materials of the present invention.

[0059] Suitable PAEKs may have repeating units of the following formula (I):

[0060]

[0061] Wherein t1 and w1 independently represent 0 or 1, and v1 represents 0, 1 or 2.

[0062] The polyaryletherketone suitably comprises at least 90 mol %, 95 mol % or 99 mol % of repeating units of formula I.

[0063] The polyaryletherketone may comprise or consist essentially of a repeating unit of formula I. Preferred polymeric materials comprise (or consist essentially of) such repeating units, wherein t1=1, v1=0 and w1=0; t1=0, v1=0 and w1=0; t1=0, w1=1, v1=2; or t1=0, v1=1 and w1=0. More preferably, the polyaryletherketone comprises (e.g. consists essentially of) a repeating unit I, wherein t1=1, v1=0 and w1=0; or t1=0, v1=0 and w1=0. The most preferred polyaryletherketone comprises (especially consists essentially of) such repeating units, wherein t1=1, v1=0 and w1=0.

[0064] In a preferred embodiment, the polyaryletherketone is selected from the group consisting of polyetheretherketone, polyetherketone, polyetherketoneetherketoneketone and polyetherketoneketone.

[0065] In a more preferred embodiment, the polyaryletherketone is polyetheretherketone or PEEK.

[0066] In some examples, polyaryletherketone (eg, PEEK) may have a thermal conductivity of at least 4KJmT. -2 , preferably at least 5KJmT -2 , more preferably at least 6KJmT-2 The Izod notched impact strength (sample 80 mm×10 mm×4 mm (type A) with a 0.25 mm notch, tested at 23° C. according to ISO 180). The Izod notched impact strength measured as described above may be less than 10 KJmT -2 , suitably less than 8KJmT -2 The Izod notched impact strength measured as described above may be at least 3 kJmT -2 , suitably at least 4 kJmT -2 , preferably at least 5 kJmT -2 The cantilever beam notched impact strength can be less than 50KJmT -2 , suitably less than 30KJmT -2 .

[0067] Polyaryletherketone (eg PEEK) suitably has a strength of at least 0.06 kNsm -2 The melt viscosity (MV) is preferably at least 0.09 kNsm -2 , more preferably at least 0.12 kNsm -2 MV. Polyaryletherketone (eg, PEEK) may have an MV of less than 1.00 kNsm -2 , preferably less than 0.5 kNsm -2 MV.

[0068] Polyaryletherketone (e.g., PEEK) can be amorphous or semi-crystalline. Polyaryletherketone is preferably crystallizable. Polyaryletherketone is preferably semi-crystalline. For example, as described by Blundell and Osborn (Polymer 24,953,1983), the level and degree of crystallinity in the polymer is preferably measured by wide-angle X-ray diffraction (also referred to as wide-angle X-ray scattering or WAXS). Alternatively, the crystallinity can be evaluated by differential scanning calorimetry (DSC).

[0069] The composite material may include any suitable amount of polyaryletherketone (e.g., PEEK). For example, the composite material may include at least 20% by volume, preferably at least 25% by volume, more preferably at least 30% by volume, still more preferably at least 35% by volume, even more preferably at least 37% by volume, and most preferably at least 39% by volume of polyaryletherketone (e.g., PEEK). The composite material includes up to 48% by volume of polyaryletherketone (e.g., PEEK). In some embodiments, the composite material may include up to 45% by volume, up to 43% by volume of polyaryletherketone (e.g., PEEK).

[0070] In some embodiments, the composite material may include 20% to 48% by volume, preferably 30% to 48% by volume, more preferably 35% to 48% by volume, and still more preferably 37% to 48% by volume or 38% to 48% by volume of polyaryletherketone (e.g., PEEK). More preferably, the composite material may include 39% to 48% by volume, even more preferably 39% to 45% by volume of polyaryletherketone (e.g., PEEK). In some embodiments, the composite material may include 39% to 43% by volume of polyaryletherketone (e.g., PEEK).

[0071] The volume ratio of the reinforcing fiber to the polyaryletherketone (eg, PEEK) is 1.1:1 to 1.5:1, such as 1.2:1 to 1:4:1.

[0072] Reinforcement Fiber

[0073] Any suitable reinforcing fiber can be used. The fiber used can be selected from an inorganic fiber material or an organic fiber material. The fiber may have a melting temperature or decomposition temperature greater than 200°C, for example greater than 250°C or greater than 300°C. In some embodiments, the fiber may have a melting temperature greater than 350°C or 500°C. Examples of suitable fibers include aramid fibers, carbon fibers, glass fibers, carbon fibers, silica fibers, zirconium oxide fibers, silicon nitride fibers, boron fibers, and potassium titanate fibers. The most preferred fiber is carbon fiber.

[0074] The reinforcing fibers (eg carbon fibers) may have a tensile strength greater than 4200 MPa, preferably greater than 4500 MPa, more preferably greater than 4800 MPa.

[0075] The reinforcing fibers (eg, carbon fibers) may have a tensile modulus greater than 200 GPa, preferably greater than 230 GPa, more preferably greater than 240 GPa.

[0076] Reinforcing fiber (e.g., carbon fiber) may have a failure strain greater than 1.1%, preferably greater than 1.2%, 1.4% or 1.6%. Reinforcing fiber (e.g., carbon fiber) may have a failure strain less than 2.2%, such as less than 2.0% or 1.9%. In some embodiments, reinforcing fiber (e.g., carbon fiber) may have a failure strain of 1.2% to 2.2%, such as 1.4% to 2.0% or 1.6% to 1.9%. In one embodiment, reinforcing fiber (e.g., carbon fiber) may have a failure strain of 1.7% to 1.9%.

[0077] The mass per unit length of reinforcing fibers (eg, carbon fibers) may be 0.1 g / m to 1.0 g / m, such as 0.2 g / m to 0.8 g / m. In some embodiments, the mass per unit length is 0.2 g / m to 0.5 g / m.

[0078] Reinforcement fibers (e.g., carbon fibers) may have a g / cm 3 , preferably greater than 1.70 g / cm 3 The reinforcing fibers (e.g., carbon fibers) may have a density of less than 1.85 g / cm 3 , preferably less than 1.80 g / cm 3 In some embodiments, the reinforcing fibers (eg, carbon fibers) may have a density of 1.70 g / 3 Up to 1.85g / 3 , for example 1.75g / 3 Up to 1.80g / 3 , or 1.78g / 3 Up to 1.79g / 3 density.

[0079] Reinforcement fibers (e.g., carbon fibers) can be provided in the form of continuous tows. Any suitable tow size can be used. The tow size indicates the number of filaments in the tow. In some embodiments, the tow size can be 1000 to 24,000. In one embodiment, a tow size of 6000 to 12,000 can be used.

[0080] Examples of suitable reinforcing fibers include, for example, Trademark Supply of carbon fiber.

[0081] Reinforcing fibers (e.g., carbon fibers) can be present in an amount of 30% to 68% by volume, preferably 40% to 65% by volume. Preferably, based on the total volume of the composite material, reinforcing fibers can be present in an amount of 50% to 62% by volume, such as 52% to 58% by volume.

[0082] The reinforcing fibers (e.g., carbon fibers) may be formed into filaments. Any suitable method may be used. For example, the reinforcing fibers may be twisted or braided to form filaments. In the case where the composite material forms a belt, the filaments may be substantially aligned along the longitudinal axis of the belt.

[0083] The amount of reinforcing fibers (eg, carbon fibers) in a composite material can be controlled within a narrow range so that the composite material provides an optimized balance of mechanical properties.

[0084] In some embodiments, the composite material further comprises a contrast agent, such as barium sulfate. For example, barium sulfate may be present in the composite material in an amount of 2% to 20% by weight, such as 3% to 10% by weight, based on the total weight of the composite material. In a preferred embodiment, the amount of barium sulfate may be 4% to 8% by weight, more preferably 4% to 6% by weight. In a most preferred embodiment, the amount of barium sulfate may be 5% by weight.

[0085] By using a controlled amount of reinforcing fibers (e.g., carbon fibers) in combination with a contrast agent (e.g., barium sulfate), it is also possible to alter the properties of the composite material in terms of imageability, such as under X-rays. For example, while barium sulfate can provide sufficient radiopacity for an implantable device to be detected, such as under X-rays, the amount of reinforcing fibers (e.g., carbon fibers) is controlled within a narrow range to provide or maintain sufficient radiopacity to allow detection of fractures in the underlying bone under imaging techniques such as X-rays.

[0086] Furthermore, by using controlled amounts of reinforcing fibers (eg, carbon fibers) in combination with barium sulfate, the radiolucency of the composite material can be optimized to reduce interference so that dose accuracy during radiation therapy can be maintained.

[0087] Contrast agents

[0088] Any suitable contrast agent can be used. Preferably, the contrast agent is detectable by X-rays. In some embodiments, the contrast agent comprises barium. For example, the contrast agent can be barium sulfate.

[0089] Barium sulfate is a contrast medium that allows the composite material to be detected under imaging techniques (e.g., X-rays). Thus, when the composite material is used to make an implantable device, the device can be detected, for example, under X-rays.

[0090] Barium sulfate may have a D in the range of 0.1 micron to 1.0 micron. 10 Particle size; D 50 The particle size is in the range of 0.5 micron to 2.0 micron, and D 90 The particle size ranges from 1.0 micron to 5 microns. 10 The particle size may be in the range of 0.1 micron to 0.6 micron, preferably in the range of 0.2 micron to 5 micron. 50 The particle size may be in the range of 0.7 microns to 1.5 microns, preferably in the range of 0.8 microns to 1.3 microns. 90 The particle size may be in the range of 1.5 microns to 3 microns, preferably in the range of 2.0 microns to 2.5 microns.

[0091] Suitable X-ray grade barium sulfate is available from Merck Millipore

[0092] Any suitable amount of contrast agent, such as barium sulfate, can be used. For example, the contrast agent (e.g., barium sulfate) can be present in the composite material in an amount of 2% to 20% by weight, preferably 3% to 15% by weight, such as 3% to 10% by weight. In a preferred embodiment, the amount of the contrast agent (e.g., barium sulfate) can be 3% to 8% by weight, more preferably 3% to 5% by weight or 4% to 6% by weight. In a most preferred embodiment, the amount of the contrast agent (e.g., barium sulfate) can be 5% by weight.

[0093] The amount of contrast agent (eg, barium sulfate) can be controlled so that the radiolucency of the composite material is optimized to reduce interference. This can allow dose accuracy to be maintained during radiation therapy.

[0094] In addition, by controlling the relative amount of reinforcing fibers (e.g., carbon fibers) to barium sulfate, it is also possible to change the properties of the composite material in terms of imageability, such as under X-rays. For example, the relative amount of reinforcing fibers (e.g., carbon fibers) to barium sulfate can be controlled to allow detection of implanted devices, such as under X-rays, while maintaining sufficient permeability to allow detection of fractures in the underlying bone.

[0095] In addition, the relative amounts of reinforcing fibers (eg, carbon fibers) to barium sulfate can be controlled so that the radiolucency of the composite is optimized to reduce interference. This can allow for maintaining dose accuracy during radiation therapy.

[0096] Composite Materials

[0097] Composite materials can be formed into bands. For example, reinforcing fibers (e.g., carbon fibers) can be combined with polyaryletherketones (e.g., PEEK) and form bands. Multiple bands can be coupled to form a layer, and the layer can be compression molded to form the compression molded main body of the device. In one embodiment, polyaryletherketones (e.g., PEEK) can be heated to a temperature higher than its softening temperature or melting temperature to melt or soften the polymer around the fibers to form a composite material. Then, the melted or softened polymer is compressed around the fibers.

[0098] When heating, suitable temperatures include 320°C and higher temperatures, preferably 330°C and higher temperatures, more preferably 340°C and higher temperatures. In some embodiments, compression molding can be carried out at a temperature of 320°C to 450°C, preferably 330°C to 400°C, more preferably 340°C to 380°C, and still more preferably 350°C to 370°C. Suitably, a pressure of at least 1.5MPa or at least 2MPa may be applied. An example of a suitable pressure range is 1.5MPa to 10MPa, such as 2MPa to 8MPa.

[0099] The tape or layer formed using the composite material of the present invention may have a thickness of 10 micrometers to 1 mm, preferably 100 micrometers to 300 micrometers, more preferably 140 micrometers to 200 micrometers.

[0100] Although the specific embodiments of the bone plates described herein are generally elongated and have opposing sides extending in a longitudinal direction, it should be understood that the concepts of the present invention also extend to plates having other shapes, such as V-shaped, Y-shaped, triangular or trilobal, as examples only.

[0101] The invention is described herein in the context of bone plates and the like for surgical reconstruction, but it will be appreciated that it has broader applicability to other fields of application, such as plates for securing components in aerospace assemblies.

[0102] Throughout the description and claims of this specification, the words "comprise" and "contain" and their variations mean "including but not limited to", and they are not intended to (and do not) exclude other parts, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural, unless the context requires otherwise. In particular, where the indefinite article is used, the specification should be understood to contemplate the plural as well as the singular, unless the context requires otherwise.

[0103] Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All features disclosed in this specification (including any accompanying claims, abstract and drawings) and / or all steps of any method or process so disclosed may be combined in any combination, except for at least some mutually exclusive combinations of such features and / or steps. The invention is not limited to the details of any foregoing embodiments. The invention extends to any novel feature or any novel combination of features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel step or any novel combination of steps of any method or process so disclosed.

[0104] The reader's attention is directed to all papers and documents which are filed concurrently with or prior to this specification in conjunction with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

Claims

1. A device comprising a compression molded body portion, the compression molded body portion comprising one or more layers of a fiber reinforced composite material; wherein the body portion is substantially planar, having opposing first and second face surfaces and a peripheral edge profile defined between the first and second face surfaces, and the body portion includes a plurality of holes extending between the face surfaces; wherein The peripheral edge is non-linear between adjacent holes, and wherein the peripheral edge is formed by cutting or machining.

2. The device of claim 1 , wherein the body is elongated having a longitudinal axis extending between opposite first and second ends of the body and opposite first and second sides extending in the longitudinal direction and forming at least a portion of the peripheral edge.

3. The device of claim 2, wherein the first side and the second side are substantially parallel to each other.

4. A device according to claim 2 or claim 3, wherein at least one of the holes is arranged on the longitudinal axis.

5. The device of claim 4, wherein the body portion is substantially symmetrical about the longitudinal axis.

6. A device according to any one of claims 2 to 5, wherein the peripheral edge has a maximum lateral width between the first side and the second side opposite to each of the holes in a straight line, and has a minimum lateral width between the first side and the second side opposite to each of the holes in the area between the adjacent holes.

7. The device according to claim 6, wherein the ratio of the maximum lateral width to the minimum lateral width is in the range of 1.1 to 1.4, preferably in the range of 1.15 to 1.

3.

8. A device according to any preceding claim, wherein the peripheral edge is concave between adjacent apertures.

9. The device of claim 8, wherein the peripheral edge has a complex curvature adjacent each aperture, wherein a convex curvature concentric with each of the apertures transitions to a concave curvature between the apertures.

10. Apparatus according to any preceding claim, wherein the minimum amount of material between each aperture and the associated peripheral edge is 2.00 mm.

11. A device according to any preceding claim, wherein the compression moulded body portion comprises a layer of the composite material comprising PEEK and carbon fibre.

12. A device according to any preceding claim which is an implantable medical device.

13. The device of claim 12 which is a bone plate.

14. A method of manufacturing a device, the method comprising: laying one or more layers of fiber-reinforced composite material into a compression mold; laminating the one or more layers of the composite material together to form a substantially planar body portion of the device, the body portion having opposing upper and lower surfaces and a peripheral edge contour defined between the upper and lower surfaces; machining the body portion to form a plurality of holes therethrough between the upper surface and the lower surface; and The peripheral edge profile between adjacent holes is machined into a non-linear profile.

15. A method of manufacturing a device, the method comprising: laying one or more plies of a fiber reinforced composite material into a compression mold, wherein each ply has at least one nonlinear side edge formed by cutting; laminating said one or more layers of said composite material together to form a substantially planar body portion of said device, said body portion having opposing upper and lower surfaces and a nonlinear peripheral edge profile defined between said upper and lower surfaces and defined by said at least one nonlinear side edge; and The body portion is machined to form a plurality of holes therethrough between the upper and lower surfaces such that at least a portion of the peripheral edge profile between adjacent holes is non-linear.

16. A method according to claim 14 or claim 15, which is a method of manufacturing a device according to any one of claims 1 to 13.

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