Femoral element for knee spacer device

Abstract

The invention relates to a femoral element (1) for a spacer device (2) of a knee joint.

Description

Technical Field

[0001] The present invention relates to a femoral component of a spacer device for a knee joint and also to a spacer device for temporarily replacing a knee joint prosthesis which has to be removed, for example after an infection has occurred. Background Art

[0002] In the field of joint prosthesis implantology, it is well known that joint prostheses may be easily removed for various reasons, especially in the case of local infection of the joint after implantation of the prosthesis.

[0003] In this case, it is not possible to replace the infected prosthesis with a new one immediately, as the joint area must be treated with appropriate antibiotic medication. During the period of time required for antibiotic treatment, it is important to maintain the joint space necessary for the implantation of the new prosthesis, thereby preventing tissue shortening, joint atrophy and loss of muscle tone. This technique is known as the "two-step implantation" of joint prostheses.

[0004] Temporary joint spacer devices for the knee are known, which are manually made by the surgeon during the spacer implantation operation. Such spacer devices are made of bone cement and are manually shaped appropriately just before implantation into the joint site.

[0005] There are spacer devices on the market for joints that are pre-shaped and do not require manual shaping during surgery before being implanted in the joint.

[0006] However, this device has the disadvantage that it is composed of a femoral part and a tibial part having standard sizes and being pre-coupled to one another, and therefore is not always easy to adapt to the anthropomorphic dimensions of each patient.

[0007] One consequence of the incorrect adaptation of known spacer devices to the anthropomorphic dimensions of the patient is that a good mobility of the joint and a good resistance of the spacer device itself to the stresses, in particular lateral stresses, to which it is usually exposed during use are not ensured. As a result, the patient has a poorer quality of life while waiting for a new joint prosthesis, and there is a need for a human joint spacer device that overcomes the above-mentioned disadvantages.

[0008] International application published as WO2018015878A1 teaches a modular spacer device for a knee joint, comprising a tibial element attachable to the tibial bone, and a femoral element attachable to the femoral axis and articulatingly engaged with the tibial element.

[0009] Furthermore, the femoral component has an articulating (articulating) surface to the tibial component that is convex and laterally has an "ammonite" type curved profile with a radius of curvature that gradually increases from the posterior section to the anterior section.

[0010] While such spacer devices ensure good performance on the one hand, they are not easy to remove from the corresponding molds, taking into account the specific configuration.

[0011] US2016206434A1 and US2016128840A1 teach other solutions according to the state of the art. Summary of the invention

[0012] It is therefore a primary object of the present invention to improve the prior art of spacer devices for the human knee joint.

[0013] Another object of the present invention is to provide a new femoral component for a spacer device which is effective and can be molded in a simple and fast manner.

[0014] Another principal object of the present invention is to provide a femoral component as described above which can be molded and adapted to the anthropomorphic measurements of each patient.

[0015] According to one aspect of the present invention, a femoral component for a knee joint according to claim 1 is provided.

[0016] According to another aspect of the present invention, a spacer device for a knee joint according to claim 17 is provided.

[0017] The dependent claims relate to preferred and advantageous embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Further features and advantages of the invention will become more apparent from the detailed, non-exclusive description of preferred embodiments of the femoral component and knee spacer device according to the invention, given by way of non-limiting examples in the accompanying table of drawings, in which:

[0019] - Figure 1 is a front view of a femoral component of a spacer device according to the present invention;

[0020] - Figure 2 yes Figure 1 Posterior view of the femoral element;

[0021] - Figure 3 yes Figure 1 A top view of the femoral component;

[0022] - Figure 4 yes Figure 1 A perspective view of the femoral element of , viewed slightly from above;

[0023] - Figures 5 to 7 yes Figure 1 lateral view of the femoral element, each with corresponding indications;

[0024] - Figure 8 yes Figure 5 A zoomed-in detail view of the

[0025] - Fig. 9 and Fig.10 is a slightly top perspective view of a spacer device according to the invention in two respective operating positions; and

[0026] - Fig.11 yes Fig. 9 and Fig.10 An exploded perspective view of a spacer device; DETAILED DESCRIPTION

[0027] To better explain the structure of the present invention, for the description of the femoral components and spacer devices, reference will be made to the planes of symmetry and axes of the body in which they are implanted, as well as a function of how (at what location and in what relative arrangement) they are implanted, such as one or more of the following:

[0028] - a front plane, which is a vertical plane, in which the direction from one side to the other of a person, considering the person in an upright position, lies and with which, for example, half the thickness of the person's body intersects;

[0029] - the sagittal plane, which is the vertical plane in which, considering a person in an upright position, the direction from the front to the back of the person lies and with which, for example, half the width of the person's body intersects;

[0030] - the transverse plane, i.e. the horizontal plane, considering a person in an upright position, for example intercepting the person's body at waist height;

[0031] - the craniocaudal axis, i.e. the vertical axis, considering a person in an upright position, intercepting the body of this person, for example, with half the thickness of the body and half the width;

[0032] - the sagittal axis, which is the horizontal axis and runs from the front to the back of the person, which, considering the person in an upright position, would intercept the person's body, for example, at half the width of the person's body;

[0033] - A side-to-side axis, which is a horizontal axis and is in the direction from one side of a person to the other side, which, considering a person in an upright position, would intercept the person's body, for example, at half the thickness of the person's body.

[0034] In addition, indications such as "posterior", "anterior", etc. should be expressly interpreted as relating to the positioning of the femoral component or spacer device in an upright position in the human body, for example, the posterior component or section is placed at the back of the knee or closer to the back or posterior portion of the knee during use.

[0035] Referring to the drawings, there is shown a femoral component 1 of a spacer device 2 for a knee joint designed to be constrained to the femoral head and having a generally "C" shaped planar configuration wherein each free end of the "C" defines a condyle or posterior leaflet 4 of the femoral component.

[0036] The device according to the invention is envisaged for implantation in the bone or joint region of the human knee, for example for:

[0037] Replace infected implants.

[0038] A spacer device is "temporary" because once it has served its function of healing and maintaining space between bones or joint parts, it is removed from the knee and replaced with a permanent prosthesis.

[0039] In this regard, the spacer device performs the function of maintaining the joint space and treating the bone infection by releasing a certain amount of antibiotics or drugs or medical substances in the infected area. In this regard, the spacer can cure the ongoing infection by releasing pharmacological substances such as antibiotics in a targeted manner and in a micro-amount, while the same result cannot be obtained even with high doses of antibiotics but using methods without providing a spacer, such as washing the infected area with a high dose of antibiotic solution.

[0040] In addition, the femoral element 1 has a first surface 5 for articulation or engagement, for example by rotation and / or translation, and a second surface 6 opposite to the first surface 5, wherein in use, the first surface faces the tibial element 3 and is used to articulate the femoral element 1 on the tibial element 3 or on its surface or to articulate with the tibial element 3 or on its surface, and the second surface 6 is used to attach to the femoral bone with the aid of a suitable fluid or compound.

[0041] It is then noted that the first surface 5 has at the rear or at each posterior leaflet or condyle 4 an end section or posterior end section 5a which opens or extends to a free or end edge 4a of the posterior leaflet or condyle 4, which end section 5a is substantially straight and extends so as to be substantially parallel to the craniocaudal axis or slightly inclined relative to the craniocaudal axis, for example between 0° and 10° or between 0° and 5° or between 0° and 3° relative to the craniocaudal axis in use.

[0042] Of course, this expression means that the terminal segment 5a is essentially parallel or located in the front plane, or in any case forms an angle between 0° and 10° or 0° and 5° or 0° and 3° with the front plane, and the distance between the terminal segment and the front part of the femoral element 1 at the free edge 4a is greater than the distance between it and the base shared by the adjacent subsequent segment of the first surface 5.

[0043] Alternatively, the end section 5a is slightly curved, but the radius of curvature is very large, significantly larger than the radius of curvature of an adjacent subsequent section of the first surface 5, such as the rear section 5d which will be better discussed later, ie at least 3 / 2 or twice or three times.

[0044] Thus, for example, the radius of curvature of the end segment 5a can even be greater than 20, 30, 40, 50 or 60 mm, while the corresponding center of curvature can be between the end segment 5a and the front of the femoral element 1, or even beyond the front of the femoral element 1, and have a suitable position along the craniocaudal axis, for example essentially at the same level as the center of curvature of other segments of the first surface 5, or also at a different level.

[0045] Advantageously, the terminal section 5 a extends from the free or terminal edge 4 a of each condyle 4 over an amount equal to at least 60%, 70%, 80% or 90% of the condyle 4 .

[0046] Basically, the end section 5a has two lengths 5a1, 5a2, one for each posterior leaflet or condyle 4.

[0047] If desired, the end section 5a extends from the free edge or end edge 4a of the condyle 4 by about 15 to 20 millimeters, for example about 18 to 19 millimeters.

[0048] Preferably, the condyle 4 has a free or terminal edge 4a having a surface 4al which is at the upper part in use and is substantially straight, with a main extension aligned with or parallel to the side-to-side axis and which, if desired, may extend in or parallel to the transverse plane.

[0049] More preferably, the upper surface 4a1 is straight and extends to at least 60%, 70%, 80% or 90% of the width or maximum dimension of the condyle 4 in the lateral to lateral axis direction.

[0050] In this regard, the width or dimension of the condyle 4 in the side-to-side axis direction is substantially constant, or increases by less than 30%, 20% or 10% in a direction away from the upper surface 4a1.

[0051] Advantageously, each free or end edge 4a is provided with a main upper surface 4al and then with two front connecting portions 4a2 and rear connecting portions 4a3, which can have a circular profile if necessary, one for connecting or continuing with the main end section 5a and the other for connecting or continuing with the rear section of the second surface 6.

[0052] Lateral portions 4a4, 4a5 may then be provided, even providing the same circular profile if necessary, for connecting each free or terminal edge 4a with the flank or side of the condyle 4.

[0053] Advantageously, the first surface 5 of the femoral element 1 is convex for all or part of its extension, naturally having a convex shape facing the corresponding femoral bone in use, and having a substantially nail-shaped curved profile in the sagittal plane or parallel to the sagittal plane, with an anterior section 5b having a first radius of curvature R1, at least one central section 5c having a second radius of curvature R2 less than or greater than the first radius of curvature R1, and then at least one posterior section 5d having a third radius of curvature R3 less than or equal to the first radius of curvature R1 and / or the second radius of curvature R2. Of course, sections 5b, 5c and 5d are continuations of another section.

[0054] Obviously, the convex shape may concern the sections 5b, 5c, 5d and, if desired, but not necessarily, also the end section 5a.

[0055] The radii of curvature R1, R2 and R3 are shown in the drawings in a simplified manner with reference to the corresponding circumferences, but it should be understood that they are also the radii of the corresponding circumferences.

[0056] Of course, the configuration of the first surface 5 preferably remains substantially constant or varies in proportion as it moves along the side-to-side axis in a plane parallel to the sagittal plane, but preferably does not vary in overall configuration, clearly taking into account the posterior C-shaped configuration and, as will be described hereinafter, the fact that it can define a central channel 14 in the center.

[0057] In this example, the terminal section 5 a may extend from the rear end 5 d 1 of the rear section 5 d of the first surface 5 .

[0058] Furthermore, a curved or straight front end section 5e of the first surface may be arranged at the front of the femoral element 1, which constitutes the front continuation of the front section 5b.

[0059] If desired, a distance H1 from a center of rotation CR2 of the second radius of curvature R2 to a center of rotation CR1 of the first radius of curvature R1 along or parallel to the sagittal axis is equal to about 1 to 3 millimeters, such as about 1.5 millimeters.

[0060] A distance H2 from the center of rotation CR2 of the second radius of curvature R2 to the center of rotation CR1 of the first radius of curvature R1 along or parallel to the craniocaudal axis is equal to about 2 to 6 millimeters, for example about 3.7 millimeters.

[0061] According to one non-limiting example, a distance H3 from a rotation center CR3 of the third radius of curvature R3 to a rotation center CR1 of the first radius of curvature R1 along or parallel to the sagittal axis is equal to about 15 to 20 millimeters, for example about 18.5 millimeters.

[0062] If desired, a distance H4 from the center of rotation CR3 of the third radius of curvature R3 to the center of rotation CR1 of the first radius of curvature R1 along or parallel to the craniocaudal axis is equal to about 20 to 26 millimeters, such as about 23.4 millimeters.

[0063] Regarding the size of any radius of curvature:

[0064] - the first radius of curvature R1 may be, for example, between about 35 and about 45 mm;

[0065] - the second radius of curvature R2 may be, for example, between about 40 and about 50 mm; and / or

[0066] The third radius of curvature R3 may be, for example, between about 10 and about 15 mm.

[0067] As a non-limiting example:

[0068] the extension of the front section 5 b is between 10% and 60%, for example between 20% and 40%, of the extension of the first surface 5 excluding the end section 5 a ; and / or

[0069] the extension of the central section 5 c is between 10% and 60%, for example between 20% and 40%, of the extension of the first surface 5 without taking into account the end sections 5 a ; and / or

[0070] The extension of the rear section 5 d is between 5% and 30%, for example between 5% and 20%, of the extension of the first surface 5 excluding the end section 5 a .

[0071] According to a non-limiting variant, at least one recessed area 7-12 is defined on the second surface 6, which is designed to promote adhesion of the femoral element 1 to the corresponding femoral bone end during the surgical procedure for implanting the spacer device 3, with the help of a filling or constraining material or fluid, in particular bone cement and / or any other suitable material.

[0072] If desired, the recessed areas 7-12 open to the respective side (medial or lateral) of the femoral component 1 to facilitate the escape of fluids such as bone cement that should be excessively applied to constrain the femoral bone.

[0073] At least one of the recessed areas 7-12 may have an extension in the plane which is substantially greater than the corresponding depth.

[0074] In this regard, at least two posterior recessed areas 7, 8 may be provided in an L-shaped configuration, and each area has a first branch 7a, 8a opening toward the respective side (medial or lateral) of the femoral element 1 and a second branch 7b, 8b opening toward the top of the femoral element 2 and defined in the respective condyle 4 of the femoral element 3. In the present example, the first branch 7a, 8a may have an extension between about 1 / 4 and 1 / 2 of the width (side-to-side axis) of the femoral element.

[0075] As an alternative or in addition to what is now indicated, at least two medial recessed areas 9 , 10 can be provided, each of which opens onto a respective side (medial side or lateral side) of the femoral component 1 .

[0076] As an alternative or in addition to what is now indicated, at least two anterior recessed areas 11, 12 may be provided in an L-shaped configuration and have a first branch 11a, 12a opening towards the respective side (medial or lateral) of the femoral element 1 and a second branch 11b, 12b opening towards the top of the femoral element 1 and defined in the front of the femoral element 1. In the present case, the first branch 11a, 12a may have an extension between about 1 / 4 and 1 / 2 of the width of the femoral element 1 (side-to-side axis).

[0077] If desired, the second surface 6 of the femoral element 1 is concave and has a "U"-shaped curved profile in the sagittal plane or in a plane parallel to the sagittal plane, which profile includes at least a curved or straight thickness front section 6a, 6b that is inclined or curved relative to the craniocaudal axis, followed by a middle or base section 6c that is substantially parallel to the sagittal axis, and then a rear section 6d that is parallel to the craniocaudal axis or slightly inclined relative to the craniocaudal axis. The rear section 6d has two parallel sections or portions, each of which defines the interior of the corresponding posterior leaf or condyle 4.

[0078] In particular with regard to the front section 6a, 6b, according to a non-limiting embodiment shown in the figures, it is possible to have two sections 6a, 6b, one 6a being inclined relative to the other 6b.

[0079] Thus, for example, the first segment 6a of the front section can define an angle of approximately 90° to 110° relative to the middle or base segment 6c, and if desired, can define an angle of approximately 100°; the second segment 6b of the front section can define an angle of approximately 130° to 140° relative to the middle or base segment 6c, and if desired, can define an angle of approximately 135°; and the rear segment 6d can define an angle of approximately 90° to 110° relative to the middle or base segment 6c, and if desired, can define an angle of approximately 100°.

[0080] With this configuration, each posterior leaflet 4 of the femoral component 1 is bounded or defined between at least one posterior section 6 d of the second surface 6 and the distal section 5 a of the first surface 5 .

[0081] The thickness of the femoral component 1 may be constant or even variable in the proximal-distal direction or in the cranio-caudal axis.

[0082] By way of non-limiting example, the femoral element 1 according to the invention may have:

[0083] an outer length H5, ie the dimension in the sagittal plane from the front free edge to the rear free edge of the first surface 5, equal to about 60 to 80 mm, for example about 70 mm; and / or

[0084] The inner length H6, ie the dimension in the sagittal plane from the front free edge to the rear free edge of the second surface 6, is equal to about 45 to 55 mm, for example about 53 to 54 mm.

[0085] As regards the height H7 of the posterior leaflet or condyle 4, by way of non-limiting example, the free edge defining this height may be approximately 15 to 25 millimeters, for example approximately 17 to 19 millimeters, from the middle or base section 6c.

[0086] As for the height H8 of the anterior portion of the femoral element, by way of non-limiting example, the free edge defining this height may be approximately 25 to 25 millimeters, for example approximately 30 millimeters, from the middle or base section 6c.

[0087] Finally, as regards the length H9 (the distance in a transverse plane between the anterior end and the posterior end) and the width H10 (the distance in a transverse plane between the sides or flanks) of the femoral element 1, by way of non-limiting example, they can be respectively between 50 and 90 mm (length), and if necessary, between 60 and 80 mm; and between 60 and 100 mm (width), and if necessary, between 70 and 90 mm.

[0088] With reference to a view or section taken along the front plane, the first surface of the femoral element 1 or better may have (see Figure 1 and Figure 2 ) A substantially curved lower profile 13 according to a fourth curvature R4, more particularly convex, for example between about 130 and 160 mm, if necessary between about 145 and 155 mm.

[0089] The first surface 5 of the femoral element 1 may also define a central channel 14 extending according to (but not parallel to) the sagittal axis of the femoral element 1, i.e., starting from the front section 5b towards the central section 5c and the rear section 5d. The central channel 14 may be defined by a rounded edge of the femoral element.

[0090] As a non-limiting example, the width H11 of the central channel 14 may be between about 5 mm and about 30 mm, and if desired, may be between about 10 mm and about 20 mm.

[0091] On the front side, the femoral element 1 has an edge or upper contour 15 which, in use, is substantially curved downwards according to a substantially concave extension.

[0092] Obviously, the contour or the upper edge can also be configured in a different manner, for example inclined to the left or to the right.

[0093] According to a variant not shown, the femoral element 1 according to the invention may have a raised element or central rib with an anteroposterior extension, rising centrally from the second surface. This central rib will be substantially aligned with the central channel 14 in the sagittal plane.

[0094] The subject matter of the present invention also includes a spacer device, which includes a femoral element 2 and a tibial element 3 suitable for constraining to the tibial bone at the end of the tibial bone facing the knee joint, the tibial element 3 including a first surface 16 facing the femoral element during use and a second surface 17 opposite to the first surface, the first surface 16 being designed to be articulated or engaged with the first surface 5 of the femoral element, for example by rotation and / or translation, and the second surface 17 being used to constrain to the bone.

[0095] As regards the tibial element 3 of the spacer device according to the invention, it has a substantially inverted "U" shaped planar configuration, wherein the base portion of the "U" corresponds in use to the anterior section 18 of the tibial element 3 and is substantially straight.

[0096] According to one aspect of the invention, the first surface 16 of the tibial element 3 is concave and has a laterally curved profile, more specifically a concave shape that is substantially complementary to the extension of the central section 5 c of the corresponding femoral element 1 .

[0097] In one version of the invention, the first surface 16 also has a generally concave profile 19 corresponding to the lower profile 13 of the femoral component 1, with reference to a view or section taken along the frontal plane.

[0098] In another version of the invention, the first surface 16 may have a substantially flat or concave profile 19 in the front, but with a very large radius of curvature (e.g., much larger than the lower profile 13) to make it substantially flat. Even in this version, the first surface 16 acts as a bearing and articulates with the lower profile 13 of the femoral element 1.

[0099] However, in another version of the invention, the first surface 16 may have a profile 19 of asymmetrical type, since the profile 19 may have a concave shape in its medial portion and a flat profile in its lateral portion, or vice versa, depending on the specific anatomical requirements of the patient. According to this version, the tibial element 3 has a "left" or "right" profile, depending on the position of the concave portion. In all cases, the profile 19 ensures support and articulation with the lower profile 13 of the femoral element 1.

[0100] In addition, the first surface 16 of the tibial component 3 can have a raised portion or a central rib 20 having a rounded profile (as described above with reference to the central passage 14 of the femoral component). The raised portion or central rib 20 extends along the sagittal axis in the tibial component 3 and has a size or a relaxed configuration that is substantially insertable into the corresponding central passage 14 defined in the femoral component 1.

[0101] As will be readily appreciated, the central rib 20 acts as a stabilizing device because it prevents lateral displacement between the femoral component 1 and the tibial component 3 when they are coupled together as described above. In any case, the central rib 20 and the central channel 14 are sized to have a certain clearance therebetween so that the femoral component 1 can move relative to the tibial component 3 along the sagittal axis and / or the side-to-side axis.

[0102] With this configuration of the central rib 20 of the tibial element 3 and the central channel 14 of the femoral element 1, a person skilled in the art will readily understand how the femoral element of the spacer device 2 according to the invention is articulated on the corresponding tibial element 3. In fact, the femoral element 1, and more specifically its first convex surface 5, can roll and partially translate relative to the first concave surface 16 of the tibial element 3 during use, while maintaining a high lateral stability due to the specific dimensions of the central rib 20 and the corresponding central channel 14.

[0103] This rotation-translation movement is a result of the configuration of the femoral element 1 and the corresponding configuration of the tibial element 3 .

[0104] Returning to the tibial element 3 of the spacer device according to the invention, it may have a substantially flat second surface 17 and be connected (in any suitable manner) to an engagement device in a central region corresponding to a central rib 20 of the first surface 16. The engagement device is used to couple the tibial element 3 to the end of the patient's bone.

[0105] The femoral 1 and / or tibial 3 elements may also include an integral stem 21, or may be connected (removably or non-removably) to another part of these elements 1 and 3 (eg, the parts shown in the figures).

[0106] Advantageously, the femoral element 1 and / or the tibial element 3 can have different extensions in the plane according to various predetermined formats or sizes, but they always maintain a constant (i.e. independent of the format or size) construction, i.e. the size and shape of the respective central channel 14 and / or central rib 20, and / or the size and shape of the radius of curvature.

[0107] In this way, the tibial element 3 and the femoral element 1 of the spacer device according to the invention can always be coupled to one another at the respective first surfaces 16 and 5, regardless of their respective formats or sizes.

[0108] Furthermore, the central rib 20 of the tibial component 3 and the central channel 14 of the femoral component 1 are configured in such a way that if the device is pushed laterally during knee movement, the central rib 20 holds the femoral component 1 in place, ensuring correct movement and good joint stability.

[0109] The lateral stability of at least one version of the spacer device according to the invention is also due to the specific convex profile of the first surface 5 of the femoral element 1 and the corresponding concave or “sunken” profile of the corresponding first surface 16 of the tibial element 3 .

[0110] Advantageously, the different formats or sizes of the tibial element 3 and the femoral element 1 are interchangeable in order to accommodate the anthropomorphic measurements of the femoral and tibial ends of each patient, which measurements may differ from one another.

[0111] The configuration of the radii of curvature of the first surfaces 5 and 16 of the femoral 1 and tibial 3 elements allows a general mutual rolling movement as well as a mutual translational or sliding movement to be obtained between the femoral 1 and tibial 3 elements.

[0112] As a function, the patient can perform joint flexion and extension movements similar to the normal physiological movements of the knee joint.

[0113] In particular, the femoral component 1 is shaped to couple with any size of tibial component 3 so that the size of the spacer device matches the size of the bone end to which it must be connected.

[0114] In this configuration, the above-described spacer device allows for high mobility of the knee joint and natural joint-like motion between different joint portions of a patient, even in the presence of different anatomical measurements.

[0115] According to another aspect of the invention, the tibial element 3, the femoral element 1 and, if provided, the stem are pre-formed in different forms or sizes and are made of a biocompatible material that may be porous.

[0116] According to another preferred aspect of the invention, at least one plane bas-relief or extended recessed area is provided in the second surface 17 of the tibial element 3, the bas-relief or extended recessed area being much larger than the corresponding depth.

[0117] These low-relief areas are provided in exactly the same way as the femoral element 1 to promote adhesion of the tibial element 3 to the corresponding tibial bone end during surgery for implanting the spacer device by using filling material, in particular bone cement and / or any other suitable material.

[0118] Their arrangement as well as their extension may vary according to specific needs, for example according to the format or size of the tibial element 3 .

[0119] Any low relief areas in the femoral and tibial components 1, 3 form sites for receiving the aforementioned filling material, which according to one aspect of the invention may be of a hardening or curable type.

[0120] In one version of the invention, the filler material may be prepared by the surgeon during surgery and / or may be free of drugs or medical substances and / or may be added based on the surgeon's choice and the patient's needs.

[0121] In case the filling material also comprises at least one drug or medical substance, the bas-relief areas 7-12 (if provided) in practice act as reservoirs for storing such drugs or medical substances to be released in the human body, more specifically in the bone or joint region where the spacer device 2 is implanted.

[0122] Naturally, the drug or medical substance inserted into the filling material is soluble, for example at least one antibiotic is soluble, so that it is released into the adjacent bone tissue or in contact with the filling material to cure or at least prevent infection thereof.

[0123] In one version of the invention, the filler material is non-absorbable or degradable within the body, at least for the time that the spacer device remains within the body. Thus, the filler material is permanent.

[0124] In one version of the invention, the surgeon applies the filler material prior to implanting the spacer device itself.

[0125] In another version of the invention, the above-mentioned filling material may therefore comprise at least one drug or medical substance already prepared in the material, which constitutes the filling material itself, and possibly another substance may be added during the preparation step.

[0126] According to one aspect of the invention, the filler material may be porous due to the preparation and curing steps it undergoes.

[0127] The pores of the filling material (and / or the material from which the femoral element 1 or tibial element 3 of the spacer device is made) are in any case sized to prevent bone regeneration inside them and inside the spacer device 2 according to the invention, which, as mentioned above, is temporary.

[0128] Such a configuration of holes thus facilitates subsequent removal of the spacer device itself from the treated bone or joint site once the therapeutic function has been completed.

[0129] For example, in one version, the average size of the pores may be less than 100 microns.

[0130] The spacer device 2 is configured such that when implanted in a human body in use, the filling material in the low-relief areas 7-12 is in contact with the bone tissue to be treated.

[0131] According to one version, the filling material is flush with the respective second surface 6 and / or 17 of the respective femoral element 1 or tibial element 3 .

[0132] According to another version, the filling material comes out of the respective low-relief area 7 - 12 , so that it protrudes relative to the second surface 6 and / or 17 of the respective femoral element 1 or tibial element 3 .

[0133] As mentioned above, the plane extension of each low-relief area 7-12 is much greater than the respective depth. Like this, be particularly convenient for the surgeon to apply the above-mentioned filling material in these areas.

[0134] According to another aspect of the invention, the tibial element 3, the femoral element 1 and, if provided, the stem are pre-formed in different forms or sizes and are made of a biocompatible material that may be porous.

[0135] Such biocompatible materials may be selected from potentially thermoformable plastics such as polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), polystyrene (PS), polyethylene (PE), ultra-high molecular weight polyethylene (UHMWPE), high-density or low-density polyethylene, etc., or non-polymer materials, ceramics, metals, metal alloys, organometallic compounds and / or combinations thereof.

[0136] In one version of the invention, the biocompatible material is a polymethylmethacrylate (PMMA) based bone cement.

[0137] In another form of the invention, the biocompatible material initially contains no drug or medicinal substance.

[0138] In another second version, the biocompatible material includes at least one drug or medical substance.

[0139] According to another version of the invention, the biocompatible material may be a ceramic cement, such as calcium sulfate known as gypsum or CaSO4, which, in addition to curing in a short time, is also capable of releasing calcium ions.

[0140] However, for the realization of the elements of the spacer device 1 according to the invention, additional biocompatible materials may be used with respect to the above without departing from the scope of the invention.

[0141] The above-described invention achieves many advantages.

[0142] Firstly, since the femoral element 1 and the tibial element 3 are pre-shaped in different sizes, they simplify the implantation step in the joint area because they do not require further shaping operations or modification of their size so that they can be adapted to the size of the bone ends, thereby reducing the time required to perform the operation.

[0143] Furthermore, due to the presence of a posterior leaflet or condyle with a substantially straight end section or in any case with a large radius of curvature, the femoral component can be easily removed from a corresponding mold.

[0144] This is clearly not possible according to the prior art, such as the spacer device taught in WO2018015878A1, which has a rear projection which is configured not to allow easy removal from the corresponding production mold.

[0145] The possibility of pre-dosing or adding to the spacer device with pharmacological and / or therapeutic products then allows treating local infections at the joint site and achieving optimal conditions for implanting a new joint prosthesis.

[0146] Modifications and variations of the invention are possible within the scope defined by the claims.

Claims

1. A femoral component of a spacer device for a knee joint, the femoral component being designed to be constrained to the femoral bone and having a substantially "C"-shaped planar configuration, wherein: Each free end of "C" defines a condyle or posterior leaflet (4) of the femoral element, the femoral element having a first articulation surface (5) facing the tibial element in use, and a second surface (6) opposite the first articulation surface for attachment to the femoral bone, Wherein, the first surface (5) has an end section (5a) at the rear or at each of the posterior leaves or condyles (4), and the end section is open or extends to the free edge or end edge (4a) of the posterior leaves or condyles (4), and the end section (5a) is basically straight and extends to be basically parallel to the head-tail axis or slightly inclined relative to the head-tail axis during use, or the end section (5a) is slightly curved, but the radius of curvature is larger, at least 3 / 2 or twice or three times that of the adjacent subsequent section of the first surface (5).

2. The femoral component according to claim 1, characterized in that The end section (5a) is substantially parallel to the front plane or lies in the front plane or in any case defines an angle of between 0° and 10° or between 0° and 5° or between 0° and 3° with the front plane.

3. The femoral component according to claim 1 or 2, characterized in that: The terminal section (5a) extends from the free edge or terminal edge (4a) of each condyle (4) to an extent equal to at least 60% of the latter.

4. The femoral component according to claim 1, 2 or 3, characterized in that: The terminal section (5a) extends from the free edge or terminal edge (4a) of each condyle (4) over an extension equal to about 15 to 20 millimeters.

5. The femoral component according to claim 1, 2, 3 or 4, characterized in that: The condyle (4) has a free or terminal edge (4a) having a substantially straight surface (4a1) which is superior in use and has a main extension aligned with or parallel to the side-to-side axis.

6. A femoral component according to any one of the preceding claims, characterized in that The first surface (5) is convex and has a basically snail-shaped curved profile in the sagittal plane or in a plane parallel to the sagittal plane, the curved profile having a front segment (5b), at least one central segment (5c) and at least one rear segment (5d), the front segment having a first radius of curvature (Rl), the at least one central segment having a second radius of curvature (R2) greater than the first radius of curvature, and then the at least one rear segment (5d) having a third radius of curvature (R3) smaller than the first radius of curvature (R1) and the second radius of curvature (R2).

7. The femoral component according to claim 6, characterized in that A distance (H1) from a center of rotation (CR2) of the second radius of curvature (R2) to a center of rotation (CR1) of the first radius of curvature (R1) along or parallel to the sagittal axis is approximately 1 to 3 mm.

8. The femoral component according to claim 6 or 7, characterized in that A distance (H2) from a center of rotation (CR2) of the second radius of curvature (R2) to a center of rotation (CR1) of the first radius of curvature (R1) along or parallel to the craniocaudal axis is approximately 2 to 6 mm.

9. The femoral component according to claim 6, 7 or 8, characterized in that: A distance (H3) from the center of rotation (CR3) of the third radius of curvature (R3) to the center of rotation (CR1) of the first radius of curvature (R1) along or parallel to the sagittal axis is approximately 15 to 20 mm.

10. The femoral component according to any one of claims 6 to 9, characterized in that A distance (H4) from a center of rotation (CR3) of the third radius of curvature (R3) to a center of rotation (CR1) of the first radius of curvature (R1) along or parallel to the craniocaudal axis is approximately 20 to 26 mm.

11. The femoral component according to any one of claims 6 to 10, characterized in that The first radius of curvature (Rl) is equal to about 35 to 45 mm.

12. The femoral component according to any one of claims 6 to 11, characterized in that The second radius of curvature (R2) is equal to about 40 to 50 mm.

13. The femoral component according to any one of claims 6 to 12, characterized in that The third radius of curvature (Rl) is equal to about 10 to 15 mm.

14. A femoral component according to any one of the preceding claims, characterised in that The second surface (6) defines at least one recessed area (7-12) designed to promote adhesion of the femoral component to the corresponding femoral bone end by means of a filling or constraining material or fluid.

15. The femoral component according to claim 14, characterized in that The at least one recessed area (7-12) opens to the corresponding side, medial side or lateral side, of the femoral component to promote the escape of fluid such as bone cement that should be applied in excess for constraining the femoral bone.

16. A femoral component according to any one of the preceding claims, characterised in that The second surface (6) of the femoral element is concave and has a "U"-shaped curved profile in the sagittal plane or in a plane parallel to the sagittal plane, and the "U"-shaped curved profile includes at least a curved or straight thickness anterior section (6a, 6b) that is inclined or curved relative to the cranio-caudal axis, followed by a middle or base section (6c) basically parallel to the sagittal axis, and then a posterior section (6d) parallel to the cranio-caudal axis or slightly inclined relative to the cranio-caudal axis.

17. A spacer device, comprising a femoral element according to any one of the preceding claims and a tibial element suitable for being constrained to the tibial bone at one end of the tibial bone facing the knee joint, the tibial element comprising a first surface (16) facing the femoral element during use and a second surface (17) opposite to the first surface, the first surface (16) being designed to be articulated or engaged with the first surface (5) of the femoral element, and the second surface (17) being used to be constrained to the bone.

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