Surgical Implants

Abstract

The present invention relates to a surgical implant (100) comprising an implant body (101) comprising a polyaryletherketone polymer material and a radiopaque marker (107) mounted with an interference fit within a bore formed in the body. The surgical implant may be manufactured by forming a polyaryletherketone body including a bore, for example by drilling the body and inserting the marker into the bore.

Description

[Technical field]

[0001] SURGICAL IMPLANTS AND METHODS FOR MANUFACTURING THEM FIELD OF THE DISCLOSURE The present invention relates to surgical implants and further to methods for manufacturing surgical implants. Particular examples of the invention relate to knee implants, for example femoral implants. [Background technology]

[0002] Prosthetic implants can be used to partially or completely replace diseased and / or damaged joint tissue. Such implants can include articulating surfaces that replace the natural articulating surfaces of the bones. For example, an implant for a knee replacement can include a femoral implant and / or a tibial implant. The femoral implant can be implanted on the distal end of the femur and can replace the articulating surface of the femur. The tibial implant can be implanted on the proximal end of the tibia and can replace the articulating surface of the tibia. During movement, the articulating surface of the femoral implant articulates against the articulating surface of the tibial implant.

[0003] A variety of materials have been used for femoral and tibial implants. For example, implants may be made from metals, such as cobalt-chromium. Metal implants may have significantly higher stiffness and tensile strength than bone. As a result, metal implants may have an increased tendency to protect the underlying bone from the stresses normally applied to a joint during use. According to Wolff's law, bone remodels in response to applied loads. If bone is shielded from these loads, it is not exposed to the stimuli required to maintain bone mass. This can lead to a loss of bone mass, which may increase the likelihood of the implant loosening. In recent years, there has been increased interest in knee implants formed from polymeric compositions that can be formulated to have mechanical properties that are more compatible with those of bone.

[0004] Accurately determining the location of the implant is important both during implantation and during post-operative monitoring of the implant. Metallic surgical implants are clearly visible under standard imaging modalities such as x-rays. This is not the case for polymeric implants. Therefore, polymeric implants are often manufactured to include one or more radiopaque markers such as beads or wires. The markers appear as bright dots on x-rays, which allow localization measurements to be made to ensure accurate placement of the component relative to the patient's anatomy.

[0005] Roentgen Stereophotogrammetry, also known as Roentgen Stereophotogrammetric Analysis (RSA), is an established technique for the assessment of three-dimensional movement and micromotion of joint replacement prostheses relative to the bones to which they are attached. Implant movement, when measured weeks and months after implantation, has been found to predict long-term implant survival and is therefore particularly useful during clinical trials for new joint replacement surgical implants. RSA is performed by attaching radiopaque markers to the bone and implant to act as artificial landmarks. Synchronized x-ray foci are used to obtain a stereoscopic image of the bone and implant, allowing the coordinates of the bone and implant markers to be precisely measured and the three-dimensional positions of the markers to be reconstructed using software. The change in position (translation and rotation) of the implant marker relative to the bone marker can then be determined.

[0006] Tantalum (Ta) is a hard transition metal that is highly corrosion resistant. It is also highly bioinert and therefore suitable for use in orthopedic implants. It is a non-ferrous, non-magnetic metal, making it suitable for patients undergoing MRI procedures. Tantalum is suitable for use as a radiopaque marker and has been found to be very visible using radiographic imaging to position implants during surgery.

[0007] In the case of metallic surgical implants, there is a risk that the metal implant may obscure the location of the tantalum marker. In the example of a cobalt-chromium femoral knee implant, it is known to provide a turret that houses a tantalum marker. The turret comprises a protrusion away from the peripheral part of the implant (e.g. the tip of the condyle, post or anterior flange) and the tantalum marker is attached to the tip of the turret. Because the marker is located at the periphery of the implant, there is a greater chance that the marker is visible under RSA. However, because the marker is located away from the critical area of ​​interest (the bone / implant interface), less accurate information about micromotions at the bone / implant interface is obtained.

[0008] Because polymer implants are radiolucent, tantalum markers can be located anywhere in or on the implant and can be directly observed under RSA. Additionally, polymer implants are softer than metal implants and therefore more easily machined to attach markers. However, attaching the markers permanently and securely remains difficult. As an example, it is known to form implants from Ultra-High Molecular Weight Polyethylene (UHMWPE). However, because UHMWPE is relatively elastic, there is a risk that the marker may come loose and pop out.

[0009] It is an object of certain examples of the present invention to at least partially solve, mitigate, or eliminate at least one of the problems and / or disadvantages associated with the prior art. Particular examples are directed to providing at least one of the advantages set forth below. Summary of the Invention

[0010] According to a first aspect of the present invention, there is provided a surgical implant comprising an implant body comprising a polyaryletherketone polymer material and a radiopaque marker mounted with an interference fit within a bore formed in the body.

[0011] The polyaryletherketone may be polyetheretherketone (PEEK).The marker may be formed from a metal, preferably tantalum.

[0012] The marker may be mounted at the base of the bore.

[0013] The bore may have a first diameter and the marker may have a second diameter that is equal to or greater than the first diameter. The second diameter may be at least 5% greater than the first diameter, optionally at least 7.5% greater, optionally no greater than 11%, and optionally in the range of 7.6% to 10.7% greater. The first diameter may be between 0.1 mm and 2 mm, optionally no greater than 1 mm, optionally 0.3 mm to 0.6 mm, optionally about 0.46 mm, and the second diameter may be between 0.1 mm and 2 mm, optionally no greater than 1 mm, optionally 0.3 mm to 0.7 mm, optionally about 0.5 mm.

[0014] The bore may have a depth of 1 mm to 2 mm, optionally about 1.5 mm, the distance from any part of the bore to the outer surface of the implant body may be at least 1 mm, optionally at least 2 mm, the bore may have a countersunk opening or may be perpendicular to the surrounding surface of the implant body or may be inclined at an angle of 30° or less, optionally about 20°, to the surrounding surface of the implant body.

[0015] The implant body may have an interior or bone-facing surface and the bore is formed in the interior or bone-facing interface.

[0016] There may be at least two spaced apart bores formed in the implant body and a marker mounted within each bore, with at least one marker being elongated, or there may be at least three spaced apart bores formed in the implant body and a marker mounted within each bore.

[0017] Each bore may be located adjacent a periphery of the implant body.

[0018] The surgical implant may be a knee implant. The surgical implant may be a femoral knee implant. The first bore may be formed in a tip of a post that extends in use away from the articulating portion of the implant body towards the femur, the second bore may be formed proximal to a tip of a condyle of the implant body, and the third bore may be formed proximal to a tip of an anterior flange of the implant body. The implant body may have a pair of posts that extend in use from the articulating interface of the implant body towards the femur, with a bore formed in each tip, or the implant body may have two condyles, with a bore formed proximal to each tip.

[0019] According to a second aspect of the invention there may be provided a method of manufacturing a surgical implant comprising forming an implant body comprising a polyaryletherketone polymer material, preferably PEEK, the body including a bore, and inserting a radiopaque marker into the bore, the radiopaque marker being seated within the bore with an interference fit.

[0020] The polyaryletherketone may be polyetheretherketone (PEEK).

[0021] The claimed method may further include injection molding the implant body and drilling into the body to form a bore. The drilling may include drilling into the implant body with a drill bit having a diameter larger than the intended bore diameter. The method may further include pushing the marker into the bore using a tool having a rod portion.

[0022] An advantage of certain examples of the present invention is that a surgical implant, such as a femoral knee component for use in knee replacement, is provided that incorporates at least one radiopaque marker that allows RSA to be performed with a reduced risk of the marker loosening. In certain examples, at least two markers are provided, at least one of which is elongated, allowing the exact location and orientation of the surgical implant to be determined. Alternatively, three markers of any shape can determine the exact location and orientation of the surgical implant. The use of a polyaryletherketone implant body allows the radiopaque marker to be positioned at any desired location, including near the bone / implant interface. [Brief description of the drawings]

[0023] Embodiments of the invention are further described below with reference to the accompanying drawings. [Figure 1] FIG. 1 is a cross-sectional view of a femoral knee implant including a radiopaque marker according to one embodiment of the present invention. [Diagram 2] 2 is an underside view of the femoral knee implant of FIG. 1 showing the location of first and second radiopaque markers on the tips of the posts. [Diagram 3] FIG. 2 is a diagram of the femoral knee implant of FIG. 1 showing the location of the third and fourth radiopaque markers on the bone interface of each condyle. [Figure 4] FIG. 2 is a diagram of the femoral knee implant of FIG. 1 showing the location of a fifth radiopaque marker on the bone interface of the anterior flange. [Diagram 5]FIG. 13 is a cross-sectional view of a bore formed in an implant body for receiving a radiopaque marker. [Figure 6] 1 is a first flowchart illustrating a method according to an example of the present invention. [Figure 7] 4 is a second flowchart illustrating a method according to an example of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The following description relates specifically to femoral knee implants by way of example, however the invention is more generally applicable to any type of surgical implant, particularly, but not exclusively, to surgical implants used in joint replacement procedures.

[0025] A surgical implant according to an embodiment of the present invention comprises an implant body formed from a polymeric material, specifically polyaryletherketone, and a radiopaque marker mounted in a bore formed in the body with an interference fit. Polyetheretherketone (PEEK) is one example of a polyaryletherketone that may be suitable for use in certain embodiments of the present invention.

[0026] The polyaryletherketone may have repeat units of formula (I):

[0027] [ka] In the formula, t1 and w1 independently represent 0 or 1, and v1 represents 0, 1, or 2.

[0028] The polyaryletherketone preferably comprises at least 90, 95, or 99 mole % of repeat units of formula I. The polyaryletherketone preferably comprises at least 90, 95, or 99 weight % of repeat units of formula I.

[0029] The polyaryletherketone may comprise or essentially consist of repeat units of formula I. Preferred polymeric materials comprise (or essentially consist of) the repeat units described above, where 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. essentially consists of) repeat units I, where t1=1, v1=0, and w1=0. Or t1=0, v1=0, and w1=0. Most preferred polyaryletherketones comprise (particularly essentially consist of) the repeat units described above, where t1=1, v1=0, and w1=0.

[0030] The polyaryletherketone may be advantageously selected from the group comprising polyetheretherketone, polyetherketone, polyetherketoneetherketoneketone and polyetherketoneketone. According to an embodiment of the invention, the polymer is in particular polyetheretherketone (PEEK).

[0031] Polyaryletherketone has a resistance of at least 4KJm -2 , preferably at least 5KJm -2 , more preferably at least 6KJm -2 The notched Izod impact strength measured as described above is 10 KJm -2 Less than 8KJm -2 The notched Izod impact strength, measured as described above, may be at least 3 KJm -2 , preferably at least 4KJm -2 , preferably at least 5KJm -2 The impact strength can be up to 50KJm -2 Less than 30KJm -2 It may be less than.

[0032] The polyaryletherketone may have a tensile strength of at least 20 MPa, preferably at least 60 MPa, more preferably at least 80 MPa, measured according to IS0527 (specimen type 1b) tested at a speed of 50 mm / min at 23° C. The tensile strength is preferably in the range of 80-110 MPa, more preferably in the range of 80-100 MPa.

[0033] The polyaryletherketone may have a flexural strength, measured according to IS0178 (3-point bending test on 80 mm x 10 mm x 4 mm samples at 23 °C at a rate of 2 mm / min), of at least 50 mPa, preferably at least 100 mPa, more preferably at least 145 mPa. The flexural strength is preferably in the range of 145 to 180 MPa, more preferably in the range of 145 to 164 MPa. The polyaryletherketone may have a flexural modulus, measured according to IS0178 (3-point bending test on 80 mm x 10 mm x 4 mm samples at 23 °C at a rate of 2 mm / min), of at least 1 GPa, suitably at least 2 GPa, preferably at least 3 GPa, more preferably at least 3.5 GPa. The flexural modulus is preferably in the range of 3.5 to 4.5 GPa, more preferably in the range of 3.5 to 4.1 GPa.

[0034] The polyaryletherketone may be amorphous or semi-crystalline. The polyaryletherketone is preferably crystallizable. The polyaryletherketone may be semi-crystalline. The level and degree of crystallinity in a polymer can be measured by wide-angle X-ray diffraction (also called wide-angle X-ray scattering or WAXS), for example, as described by Blundell and Osborn (Polymer 24,953,1983). Alternatively, crystallinity can be evaluated by Differential Scanning Calorimetry (DSC).

[0035] The level of crystallinity of the polyaryletherketone may be at least 1%, suitably at least 3%, preferably at least 5%, more preferably at least 10%. In particularly preferred embodiments, the crystallinity may be greater than 25%. It may be less than 50% or less than 40%. The main peak of the melting endotherm (Tm) of the polyaryletherketone (if crystalline) may be at least 300°C.

[0036] The polyaryletherketones described above, including polyetheretherketone (PEEK), can be used to form surgical implants, particularly implant bodies. For example, polyaryletherketones, such as PEEK, can be molded to form implant bodies. Examples of suitable molding methods include injection molding and compression molding.

[0037] The joint replacement implant body has a bone-facing interface and an articulation interface. The articulation interface may be considered an exterior interface and the bone-facing interface may be considered an interior interface. The articulation interface may be smooth, i.e., have a low coefficient of friction. Reference is now made to FIG. 1, which is a cross-sectional view of a femoral knee implant 100 including a radiopaque marker according to one embodiment of the present invention. The femoral knee implant 100 comprises an implant body 101 formed from polyaryletherketone, for example, by injection molding.

[0038] FIG. 1 shows an articulating interface 102 and a bone-facing interface 103. When implanted, the bone-facing interface 103 seats over the resected distal portion of the femur. The articulating interface 102 may be an interface that articulates against the articulating (bearing) interface of the tibial implant during use. The femoral knee implant 100 includes at least one post 104, for example, two posts 104 as shown in FIG. 2. The post 104 extends from the bone-facing interface 103 away from the articulating interface 102 to be received within a bore in the resected end of the femur when implanted. FIG. 1 also shows the femoral knee implant 100 including a condylar portion 105 and an anterior flange 106.

[0039] FIG. 1 further shows three radiopaque markers 107. Each marker 107 is fixed to the implant body 101 by being inserted into a bore formed in the implant body. For example, the bore may be drilled in the implant body 101 during the manufacturing process. The markers 107 are held in the bore with an interference fit. As explained below, the interference fit is achieved by carefully selecting the respective diameters of the bore and marker 107, along with the materials used to form each part. Because polyaryletherketones, e.g., PEEK, are relatively hard polymers, an interference fit with metal markers such as tantalum can be achieved, which may not be the case with other polymers. Each marker 107 may preferably be spherical. Optionally, the marker may be elongated, which may give further information about its orientation when observed under RSA.

[0040] When two posts 104 are present, markers 107 may be provided at or near the tip of each post 104, as described in connection with FIG. 2. Similarly, the condylar portion 105 may comprise separate condyles with markers fixed near their respective tips, as described in connection with FIG. 3. In particular, the first and second condyles may correspond to the lateral and medial condyles of the femoral tissue of the original knee joint. FIG. 4 shows the location of the markers 107 on the anterior flange in more detail. FIG. 5 shows the shape of the bore for receiving the markers 107 with an interference fit.

[0041] Advantageously, by spacing the markers 107 around the femoral knee implant 100, the position and orientation of the femoral knee implant 100 can be precisely determined. According to examples of the present invention, bores may be formed, e.g., drilled, in any suitable location of the polyaryletherketone implant body to receive the markers 107. The process of inserting the markers into the bores and securing the markers with an interference fit is described below in conjunction with Figures 5-7. In some examples, the bores are formed in the bone-facing interface 103 such that the articulation interface 102 is uninterrupted. For example, in the example of Figure 1, the markers 107 are inserted into bores (not specifically shown in Figure 1) extending from the medial side of the femoral knee implant 100.

[0042] 1, the locations of the markers 107 are selected to be widely spaced so that they can be more easily identified under RSA. That is, the markers are placed in specific locations at or near the outer edge of the implant to ensure that they can be clearly identified. However, as shown, the markers 107 may be located near the bone-facing interface 103 so that the location of this critical portion of the implant 100 is precisely located.

[0043] The shape of the markers 107 may vary. In one example, the markers 107 may be spherical or approximately spherical such that observing a single marker 107 under RSA does not provide information regarding the orientation of the implant 100 (or indeed the location of the implant 100 if it includes multiple markers 107). By providing at least three markers 107, the location and orientation of the implant can be accurately determined, as long as the markers 107 are not distributed in a rotationally symmetric pattern. In some examples, four or more markers 107 may be provided within the implant 100 to provide redundancy in case one or more markers 107 are obscured (e.g., by a second marker 107, or another metal implant, instrument, or other feature of the radiograph). In the example presented in Figures 2-4, there are five markers 107 to provide redundancy. Additionally, a greater number of markers 107 may provide more accurate location and orientation information.

[0044] In a further example, one or more markers 107 may not be spherical, such that an image of the marker itself can provide some information regarding the orientation. For example, if the marker is elongated (such as a cylinder or rod), the marker indicates the orientation of the implant 100 except for rotation about the longitudinal axis of the marker 107. It will be understood that a cylinder or rod may be fixed in a bore in the same manner as a sphere. This use of non-spherical markers may allow for a reduction in the number of markers 107 required to accurately determine the position and orientation of the implant (although again, additional markers may provide redundancy). As an example, if the first marker 107 is elongated, then only the second marker 107 of any shape, including a sphere, is sufficient to determine the position and orientation of the implant 100, unless the first and second markers 107 are collectively rotationally symmetric.

[0045] Reference is now made to Figure 2, which shows a view of the femoral knee implant 100 of Figure 1 with the post 104 aligned with the viewing axis (as the implant 100 is viewed from the medial side, revealing the bone-facing interface 103). Portions of the articulation interface 102 are shown on the anterior flange 106 and condyle portions, here shown as first condyle 105a and second condyle 105b.

[0046] In this example, a pair of markers 107 are shown, each inserted into a bore formed in the top surface of each post 104. In other examples, only one post 104 may have a marker 107, or indeed there may be only one post, for example in a more central location. Each post 104 may have a diameter of about 3 mm, with the bore being centrally located and having a diameter of, for example, 0.46 mm, as described below.

[0047] FIG. 3 shows the femoral knee implant 100 of FIGS. 1 and 2 further rotated relative to the view of FIG. 2 to reveal the bone-facing interface 103 of the first and second condyles 105a, 105b. In this example, a marker 107 is attached to each condyle 105a, 105b, but in the alternative, only one condyle 105a, 105b may include a marker 107. The bone-facing interface 107 may be generally uniform. Alternatively, as shown, it may comprise a series of cement pockets 300 separated by ribs 301 for receiving bone cement during implantation. Each marker 107 may be suitably located within a bore formed in the cement pocket 300. In particular, each marker 107 may be located within the cement pocket 300 proximate to the tip of the condyle 105a, 105b. Each condyle 105a, 105b has a centerline 302. Each marker 107 may be aligned with the centerline 302 or may be offset laterally (e.g., outwardly) as shown at 303 relative to the first condyle 105a. Suitably, the offset may be in the range of 1 mm to 3 mm, e.g., 2 mm. Additionally, each marker 107 may be offset in the range of 1 mm to 3 mm, e.g., 1.5 mm to 2 mm, from the outermost rib 301, as shown at 304 relative to the first condyle 105a.

[0048] Figure 4 is a further rotation of the femoral knee implant of Figure 3 to reveal the bone-facing interface 103 of the anterior flange 106. Again, the bone-facing interface 103 may comprise a series of cement pockets 300, separated by ribs 301, for receiving bone cement during implantation. A single marker 107 may be suitably located within the outermost cement pocket 300 of the anterior flange 106. The marker 107 may be positioned laterally centered within the cement pocket, for example, approximately 5 mm from either side as shown at 400. The marker 107 may be positioned orthogonally centered within the cement pocket, for example, approximately 2.7 mm from either side as shown at 401.

[0049] It will be understood that the exact locations of the markers 107 shown in Figures 2-4 are by way of example only.

[0050] 5, a bore 500 for receiving a marker 107 (not shown in FIG. 5) will now be described. As an example, a bore 500 formed in a cement pocket 300 is shown. The bore 500 can be formed using any suitable drilling technique known to those skilled in the art. Preferably, the bore 500 may be drilled perpendicular to the bone-facing interface 103 as shown. However, it may also be drilled at an angle to the vertical, for example up to 30°, optionally 20° or less. This may be necessary when drilling a bore in the condyles 105a, 105b to allow the drill to pass through the post 104.

[0051] It will be appreciated that the dimensions of the bore are determined by the dimensions of the marker 107, among other criteria. The following ranges are given for a spherical marker 107 having a diameter of 0.5 mm. Suitably, the bore 500 may have a depth 501 in the range of 1 mm to 2 mm, for example 1.5 mm. The base of the bore may be square or circular, as shown. A locating cone or chamfer 502 may be provided to aid in inserting the marker 107 having a depth 503 of 0.5 mm or less, for example 0.3 mm. Chamfering the bore forms a guide for the pressing action to insert the marker and helps to distribute the force evenly around the hole. It may help to allow the compression to occur gradually.

[0052] As mentioned above, the marker 107 may be inserted into the bore 500 in an interference fit. An interference fit may also be referred to as a press fit or a friction fit. It is a form of fastening between two tightly fitting mating parts that are held together by friction after being pressed together. Depending on the amount of interference fit, hand tools or optionally a hydraulic ram may be used to join the mating parts. In the present situation, the interference fit may be formed by forcing an oversized marker into an undersized hole either by applied force or thermal expansion or contraction (or a combination of both), the former option being illustrated in the examples below. For example, the inventors have determined that for a PEEK implant body 101 and a tantalum marker bead with a diameter of 0.5 mm, a suitable interference fit may be formed if the bore has a diameter of 0.46 mm. The bore may be formed using an oversized drill bit. This is due to the elasticity of polyaryletherketone. As an example, PEEK has a flexural modulus of 4.1 Gpa. As the drill bit cuts into the implant body, the material flexes to make room for the drill bit. The material contracts when the drill bit is removed, resulting in a smaller diameter hole. The exact diameter of the oversized drill bit can be determined empirically. In some examples, the diameter of the bore 500 may vary, for example, up to 1.5 mm, depending on the required diameter of the marker 107.

[0053] The bore may be formed close to the periphery of the implant, but still retain enough material around the bore to preserve the structural integrity of the implant. For example, a minimum of 2 mm of material may be required on all sides of and below the bore. In the example of a femoral knee implant, the markers may be located on the post tip, condyle tip, and anterior flange. In either case, the selected location does not include the bearing surface of the implant. That is, the marker may be inserted into the bore on the inner surface of the implant. The inner surface may be the bone-facing surface or the cement surface.

[0054] Once the bore 500 is formed, the marker 107 may be press-fitted into the bore 500 using a tool such as a rod (not shown) having a diameter that allows it to be freely inserted into the bore 500. Preferably, the marker 107 may be inserted such that it is seated at the base of the bore 500. It will be appreciated that if air is trapped behind the marker 107, this may prevent the marker 107 from being seated at the base of the bore 500. However, in practice it has been found that this does not occur as the machined surface roughness of the bore 500 and the marker 107 allows the air to dissipate around the marker 107.

[0055] A specific example of a surgical implant in which a marker is inserted into a bore with an interference fit is now presented. The implant body is formed from PEEK, for example by injection molding, and a bore having a diameter of 0.46 mm is drilled into the implant body. To ensure the exact bore diameter, the required tolerance on the drill bit is +0.000 mm and -0.004 mm. That is, the bore need not be drilled wider than the specified 0.46 mm (to three decimal places), but may be slightly smaller, resulting in a tighter interference fit. Alternatively, a spherical tantalum marker bead may be formed with a diameter of 0.5 mm and a tolerance of ±0.005 mm. By taking the maximum and minimum diameter measurements of the bore and marker, the interference can be determined to be in the range of 0.035 mm to 0.049 mm. PEEK has a flexural modulus of 4.1 GPa. Tantalum has a flexural modulus of 187 GPa. Experience has shown that this provides a strong enough interference fit that there is negligible risk of the marker becoming dislodged during surgery. In certain instances, a bore is provided on the bone-facing interface so that even if the marker may become dislodged from the interference fit after surgery, the marker is retained by the bone cement or the bone interface itself.

[0056]

[0023] Referring now to Figure 6, a method of manufacturing a surgical implant includes, at step 600, forming an implant body including a polyaryletherketone, e.g., PEEK, polymeric material, the body including a bore. At step 601, the method includes a second step of inserting a radiopaque marker into the bore such that the radiopaque marker is seated in the bore with an interference fit. Figure 6 illustrates an alternative method including first, a step of molding the implant body, preferably from PEEK (701), second, a step of drilling into the implant body to form a bore (702), and third, a step of inserting the marker into the bore with an interference fit (703).

[0057] Throughout this specification, the terms "comprise" and "contain" and variations thereof mean "including but not limited to" and are not intended to (and do not) exclude other components, integers, or steps. Throughout this specification, the singular includes the plural, unless the context requires otherwise. In particular, when the indefinite article is used, the specification should be understood as considering the plural as well as the singular, unless the context requires otherwise. Throughout this specification, the term "about" is used to provide flexibility to the endpoints of a range by providing that a given value may be "a little above" or "a little below" the endpoint. The degree of flexibility of this term can be specified by the particular variable and can be determined based on experience and the relevant explanations in this specification.

[0058] It should be understood that features, integers, or characteristics described in connection with a particular aspect or embodiment of the invention are applicable to any other aspect or embodiment described herein, unless inconsistent. All of the features disclosed herein, and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations in which at least some of such features and / or steps are mutually exclusive. The invention is not limited to the details of any of the foregoing embodiments. The invention extends to any novel feature or combination of features disclosed herein. It will also be understood that throughout this specification, language of the general form "X for Y" (where Y is some operation, activity, or step, and X is some means for performing that operation, activity, or step) encompasses, but is not exclusive to, means X that are specifically adapted or arranged to perform Y.

[0059] Each feature disclosed in this specification, unless expressly stated otherwise, may be replaced by alternative features serving the same, equivalent or similar purpose. Thus, unless expressly stated otherwise, each feature disclosed is only an example of a generic series of equivalent or similar features.

[0060] The reader's attention is directed to all articles and documents related to this application that are filed contemporaneously or prior to this application and that are open to public inspection together with this application, and the contents of all such articles and documents are incorporated herein by reference.

Claims

1. An implant body including a polyaryl ether ketone polymer material, and a radiopaque marker press-fitted into a bore formed in the body. A surgical implant.

2. The surgical implant according to claim 1, wherein the polyaryl ether ketone is polyether ether ketone (PEEK).

3. The surgical implant according to claim 1 or 2, wherein the marker is formed of a metal, preferably tantalum.

4. The surgical implant according to claim 1 or 2, wherein the marker is installed at the base of the bore.

5. The surgical implant according to claim 1 or 2, wherein the bore has a first diameter and the marker has a second diameter that is greater than or equal to the first diameter.

6. The surgical implant according to claim 5, wherein the second diameter is at least 5% greater than the first diameter, optionally at least 7.5% greater, optionally 11% or less greater, and optionally in the range of 7.6% to 10.7% greater.

7. The first diameter is from 0.1 mm to 2 mm, optionally 1 mm or less, optionally from 0.3 mm to 0.6 mm, and optionally about 0.46 mm, and the second diameter is from 0.1 mm to 2 mm, optionally 1 mm or less, optionally from 0.3 mm to 0.7 mm, and optionally about 0.5 mm. The surgical implant according to claim 5.

8. The bore has a depth of 1 mm to 2 mm, optionally about 1.5 mm, and the distance from any part of the bore to the outer surface of the implant body is at least 1 mm, optionally at least 2 mm, and the bore has a countersunk opening, or The surgical implant according to claim 1 or 2, wherein the bore is perpendicular to the peripheral surface of the implant body or is inclined at 30° or less, optionally about 20°, with respect to the peripheral surface of the implant body.

9. The surgical implant according to claim 1 or 2, wherein the implant body has an inner surface or a bone-facing surface, and the bore is formed in the inner surface or the bone-facing interface.

10. There are at least two spaced bores formed in the implant body, markers are installed in each bore, and at least one marker is elongated or The surgical implant according to claim 1 or 2, wherein there are at least three spaced bores formed in the implant body, and markers are installed in each bore.

11. The surgical implant according to claim 10, wherein each bore is located close to the peripheral portion of the implant body.

12. The surgical implant according to claim 1 or 2, wherein the surgical implant is a knee implant.

13. The surgical implant is a femoral knee implant, a first bore is formed at the tip of a column extending away from the articulating portion of the implant body towards the femur during use, a second bore is formed proximal to the tip of the condyle of the implant body, a third bore is formed proximal to the tip of the front flange of the implant body, according to the surgical implant of claim 12.

14. The implant body has a pair of columns extending from the articulating interface of the implant body towards the femur during use, and bores are formed at the tips of each, or The surgical implant according to claim 13, wherein the implant body has two beads and bores are formed proximal to each tip. **Claim 15** A method of manufacturing a surgical implant, comprising: forming an implant body comprising a polyaryletherketone polymer material, preferably PEEK, the body comprising a bore; and inserting a radiopaque marker into the bore. The radiopaque marker is press-fitted into the bore. A method. **Claim 16** The method according to claim 15, further comprising injection molding the implant body and drilling into the body to form the bore, the drilling comprising drilling into the implant body using a drill bit having a diameter larger than the intended bore diameter.

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