Femoral prosthesis and knee prosthesis

Abstract

The disclosure provides a femoral prosthesis and a knee joint prosthesis, and belongs to the technical field of medical devices. The femoral prosthesis comprises a femoral condyle joint surface; the femoral condyle joint surface has a first joint surface part for abutting against a tibial joint surface in a first knee flexion angle range, and a second joint surface part for abutting against the tibial joint surface in a second knee flexion angle range; the first knee flexion angle range is from a first knee flexion angle to a second knee flexion angle; the second knee flexion angle range is from the second knee flexion angle to a third knee flexion angle; wherein the first knee flexion angle is selected from -20 to 0°, the second knee flexion angle is selected from 45 to 75°; the third knee flexion angle is selected from 50 to 90°, and the third knee flexion angle is greater than the second knee flexion angle; the sagittal plane of the first joint surface part has a single first radius of curvature, and the radius of curvature of the sagittal plane of the second joint surface part decreases from the front end to the rear end. The femoral prosthesis can improve the stability of joint movement and reduce the wear of the knee joint prosthesis in the gait state.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of medical devices, and in particular to a femoral prosthesis and a knee prosthesis. BACKGROUND

[0002] The knee joint is the most complex joint in the human body, and it is also the joint that is most likely to be damaged. Aging and various joint diseases or injuries will cause partial or total damage to the movement function of the knee joint, resulting in joint pain and difficulty in movement for the patient. A knee prosthesis is used to replace a diseased or damaged human knee joint, and with the help of knee ligaments and soft tissues, the patient can restore the movement function of the knee joint and reduce pain. The knee prosthesis is usually designed to have the approximate shape of the human knee joint and to mimic the natural movement of the human knee joint.

[0003] The knee prosthesis can include a femoral component for connecting with the femur, a tibial component for connecting with the tibia, and a tibial insert located above the tibial component and articulating with the femoral component. When the knee prosthesis is flexed and extended, the condyle surface of the femoral component and the support surface of the tibial insert move relatively in the anterior-posterior direction and rotate in the medial-lateral direction. It is a main goal in the design of the knee prosthesis to ensure the stability of the knee movement as much as possible and to reduce the wear of the knee prosthesis during movement.

[0004] The above information disclosed in the background section is only for the purpose of enhancing the understanding of the background of the present disclosure, and therefore it can include information that does not constitute the prior art known to those of ordinary skill in the art. SUMMARY

[0005] The purpose of the present disclosure is to provide a femoral prosthesis and a knee prosthesis that improve the stability of joint movement and reduce the wear of the knee prosthesis in the gait state.

[0006] To achieve the above-mentioned purpose of the application, the present disclosure adopts the following technical solutions:

[0007] According to a first aspect of the present disclosure, a femoral prosthesis is provided, the femoral prosthesis comprising a medial condyle portion and a lateral condyle portion, the medial condyle portion and the lateral condyle portion each having a femoral condyle articulating surface for abutting a tibial articulating surface, the tibial articulating surface comprising a natural meniscus, a tibial implant, or an insert implant for abutting a femoral prosthesis articulating surface;

[0008] The femoral condyle articulating surface has a first articulating surface portion for abutting the tibial articulating surface in a first range of flexion angles, and a second articulating surface portion for abutting the tibial articulating surface in a second range of flexion angles;

[0009] The first knee flexion angle range is from a first knee flexion angle to a second knee flexion angle; the second knee flexion angle range is from the second knee flexion angle to a third knee flexion angle; wherein the first knee flexion angle is any knee flexion angle in the range of -20-0°, the second knee flexion angle is any knee flexion angle in the range of 45-75°, and the third knee flexion angle is any knee flexion angle in the range of 50-90°, and the third knee flexion angle is greater than the second knee flexion angle.

[0010] The sagittal plane of the first articular surface portion has a single first radius of curvature, and the radius of curvature of the sagittal plane of the second articular surface portion decreases from the anterior end to the posterior end.

[0011] In an exemplary embodiment of the present disclosure, the difference between the third knee flexion angle and the second knee flexion angle is 10-30°.

[0012] In an exemplary embodiment of the present disclosure, the second knee flexion angle is any knee flexion angle in the range of 50-60°, and the third knee flexion angle is any knee flexion angle in the range of 60-90°.

[0013] In an exemplary embodiment of the present disclosure, the first knee flexion angle is 0°, the second knee flexion angle is 60°, and the third knee flexion angle is 75°.

[0014] In an exemplary embodiment of the present disclosure, the second articular surface portion comprises a plurality of curved surfaces whose radii of curvature in the sagittal plane decrease successively from the anterior end to the posterior end.

[0015] In an exemplary embodiment of the present disclosure, the difference between the radii of curvature in the sagittal plane of any two adjacent curved surfaces is not greater than 1 mm.

[0016] In an exemplary embodiment of the present disclosure, the radius of curvature of the curved surface at the posterior end of the second articular surface portion is a second radius of curvature, and the ratio of the first radius of curvature to the second radius of curvature is 1.3-2.1.

[0017] In an exemplary embodiment of the present disclosure, the ratio of the first radius of curvature to the second radius of curvature is 1.5-1.9.

[0018] In an exemplary embodiment of the present disclosure, the ratio of the first radius of curvature to the second radius of curvature is 1.5-1.7.

[0019] According to a second aspect of the present disclosure, there is provided a knee joint prosthesis comprising the femoral prosthesis described above.

[0020] The femoral prosthesis and knee prosthesis provided by the present disclosure, the first joint surface part is the contact surface of the femoral prosthesis with the tibial joint surface during gait movement of the human body, which has a single radius of curvature in the sagittal plane, avoiding abnormal relative movement of the joint surface caused by the change of the curved surface, ensuring the stability of the joint movement. The second joint surface part is the femoral condyle joint surface which contacts the tibial joint surface in the high flexion state of the knee joint, and the gradually decreasing radius of curvature in the sagittal plane can maintain the stability of the knee joint in the high flexion state, while the difference between the radius of curvature of the first joint surface part and the radius of curvature of the rear end of the second joint surface part can be relatively large, so that the radius of curvature of the femoral condyle joint surface (i.e. the first joint surface part) contacting the tibial joint surface during gait movement is larger, the contact area between the femoral condyle joint surface and the tibial joint surface is maximized, and the contact stress between the femoral condyle joint surface and the tibial joint surface is reduced, thereby effectively reducing the joint wear. Gait movement is the most frequent movement state of the knee joint (prosthesis), and reducing the wear of the knee joint prosthesis under gait can effectively increase the service life of the prosthesis. BRIEF DESCRIPTION OF DRAWINGS

[0021] The above and other features and advantages of the present disclosure will become more apparent by describing in detail example embodiments thereof with reference to the attached drawings.

[0022] Figure 1 It is a schematic diagram of the cross-sectional structure of the femoral prosthesis of the present disclosure in the sagittal plane.

[0023] Figure 2 It is a schematic diagram of the cross-sectional structure of the knee prosthesis of the present disclosure in the sagittal plane.

[0024] The main element reference signs in the drawings are explained as follows:

[0025] 100, femoral prosthesis; 110, femoral condyle joint surface; 101, first joint surface part; 102, second joint surface part; 111, curved surface; 120, bone cutting surface; 130, fixing column; 200, tibial spacer; 300, tibial base; A, first contact point; B, second contact point; C, third contact point; D, fourth contact point; E, fifth contact point; z, coronal plane. DETAILED DESCRIPTION

[0026] Example embodiments now will be described more fully hereinafter with reference to the accompanying drawings. Example embodiments, however, can be implemented in many different forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of example embodiments to those skilled in the art. The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the present disclosure.

[0027] The terms "first" and "second" are used only as labels, and are not intended to denote a quantity or a limitation.

[0028] A femoral prosthesis is provided in embodiments of the present disclosure, such as Figure 1 and Figure 2 As shown in FIG. 1, the femoral prosthesis 100 includes a medial condyle portion and a lateral condyle portion, each having a femoral condyle articulating surface 110 for abutting a tibial articulating surface including a natural meniscus, a tibial implant, or a liner implant for abutting the articulating surface of the femoral prosthesis 100; wherein,

[0029] The femoral condyle articulating surface 110 has a first articulating surface portion 101 for abutting the tibial articulating surface in a first range of flexion angles, and a second articulating surface portion 102 for abutting the tibial articulating surface in a second range of flexion angles; the first range of flexion angles is from a first flexion angle to a second flexion angle; the second range of flexion angles is from the second flexion angle to a third flexion angle; wherein the first flexion angle is any flexion angle in the range of -20-0°, the second flexion angle is any flexion angle in the range of 45-75°, and the third flexion angle is any flexion angle in the range of 50-90°, and the third flexion angle is greater than the second flexion angle; the sagittal plane of the first articulating surface portion 101 has a single radius of curvature, and the radius of curvature of the sagittal plane of the second articulating surface portion 102 decreases from an anterior end to a posterior end.

[0030] In the femoral prosthesis 100 provided by the present disclosure, the first articulating surface portion 101 is the contact surface of the femoral prosthesis 100 with the tibial articulating surface during gait motion, which has a single radius of curvature in the sagittal plane, avoiding abnormal relative movement of the articulating surface caused by changes in the curvature, and ensuring the stability of the joint movement. The second articulating surface portion 102 is the femoral condyle articulating surface 110 that comes into contact with the tibial articulating surface in a high flexion state of the knee joint (for example, in a squatting state), and the gradual decrease of the radius of curvature in the sagittal plane can maintain the stability of the knee joint in a high flexion state, while the difference between the radius of curvature of the first articulating surface portion 101 and the radius of curvature of the posterior end of the second articulating surface portion 102 can be relatively large, so that the radius of curvature of the sagittal plane of the femoral condyle articulating surface 110 (i.e., the first articulating surface portion 101) in contact with the tibial articulating surface during gait motion can be larger, the contact area between the femoral condyle articulating surface 110 and the tibial articulating surface is maximized, and the contact stress between the femoral condyle articulating surface 110 and the tibial articulating surface is reduced, thereby effectively reducing joint wear. Gait motion is the most frequent motion state of the knee joint (prosthesis), and reducing the wear of the knee joint prosthesis during gait can effectively increase the service life of the prosthesis.

[0031] The components of the femoral prosthesis 100 provided in this disclosure embodiment will now be described in detail with reference to the accompanying drawings:

[0032] To better explain and illustrate the technical solutions of this disclosure, the directions, cross-sections, etc. involved in this disclosure will be explained and illustrated in conjunction with the conventional descriptive methods in this field.

[0033] In the fields of anatomy and medical devices, directions and planes such as internal, external, anterior, posterior, distal, proximal, sagittal, coronal, and cross-section have specific meanings and are well known to those skilled in the art. Unless otherwise specified, these terms refer to the meanings generally accepted by those skilled in the art.

[0034] Typically, when describing the human body, joints, or prostheses, three types of cross-sections are involved: the sagittal plane, the coronal plane (z), and the cross-section. The sagittal plane is a longitudinal section that divides the human body or joint into left and right parts along the anterior-posterior direction. The median sagittal plane, passing through the center of the human body, divides the body into two equal parts. The coronal plane (z) is a longitudinal section that divides the human body or joint into anterior and posterior parts along the lateral direction. The coronal plane (z) is perpendicular to the sagittal plane. The cross-section is a plane parallel to the ground that divides the human body or joint into upper and lower parts. The cross-section is perpendicular to both the coronal plane (z) and the sagittal plane.

[0035] Understandably, when describing a knee joint or knee prosthesis, the sagittal plane, coronal plane (z), and cross-section refer to the sections when a person is standing upright normally, at which point the knee flexion angle is 0°. When the knee joint or knee prosthesis flexes or extends, or when the body's posture is adjusted, the sagittal plane, coronal plane (z), and cross-section can change accordingly.

[0036] Typically, when describing the human body, joints, or prostheses, three different directions are involved: distal, medial, and anteroposterior. The distal end refers to the end of the body or joint relatively far from the torso. The proximal end refers to the end of the body or joint relatively close to the torso. The medial side refers to the side relatively close to the midsagittal plane of the body. The lateral side refers to the side relatively far from the midsagittal plane of the body. The anterior side refers to the side relatively close to the abdomen in the sagittal plane. The posterior side refers to the side relatively close to the back in the sagittal plane.

[0037] like Figure 2 As shown, at a specific knee flexion angle, the femoral condyle joint surface 110 abuts against the tibial joint surface. The contact surface in the sagittal plane appears as one or more consecutive contact points on the femoral condyle joint surface 110; for simplicity, these are simply described as "contact points." It is understood that there is a one-to-one correspondence between the contact points and the knee flexion angle, and those skilled in the art can determine the center of the corresponding contact point or multiple consecutive contact points on the femoral condyle joint surface 110 in the sagittal plane at a specific knee flexion angle.

[0038] It can be understood that any contact point refers to a point of the femoral condyle articular surface 110 in the sagittal plane for cooperating with the tibial articular surface, which does not mean that the femoral condyle articular surface 110 and the tibial articular surface have necessarily been in contact at the contact point. In a single sagittal plane, the contact point can be a point; in the entire femoral condyle articular surface 110, the respective corresponding contact points can be connected into a line. In other words, the femoral condyle articular surface 110 can be in line contact with the tibial articular surface, and the position of the line contact appears as the contact point in the sagittal plane.

[0039] In the femoral prosthesis 100 provided in the present disclosure, as shown in Figure 1 Any femoral condyle articular surface 110 can appear as a smooth curve in the sagittal plane, and the smooth curve includes at least a first contact point A, a second contact point B and a third contact point C. Among them, the first articular surface portion 101 appears as a curve between the first contact point A and the second contact point B in the sagittal plane; the second articular surface portion 102 appears as a curve between the second contact point B and the third contact point C in the sagittal plane.

[0040] Among them, the flexion angle corresponding to the first contact point is a first flexion angle, and the first flexion angle is any flexion angle in -20-0°. The flexion angle corresponding to the second contact point is a second flexion angle, and the second flexion angle is any flexion angle in 45-75°. The flexion angle corresponding to the third contact point is a third flexion angle, and the third flexion angle is any flexion angle in 50-90°. And the third contact point C is located on the posterior side of the second contact point B, so that the third flexion angle is greater than the second flexion angle. The sagittal plane of the first articular surface portion 101 has a single first radius of curvature, and the radius of curvature of the sagittal plane of the second articular surface portion 102 decreases from the front end to the rear end.

[0041] Optionally, the second flexion angle is any flexion angle in 50-60°, and the third flexion angle is any flexion angle in 60°-90°, so as to ensure the stability of the knee prosthesis under gait motion and increase the sagittal plane curvature radius of the contact surface under gait motion to reduce the wear caused by frequent gait motion.

[0042] Optionally, the difference between the third flexion angle and the second flexion angle is 5°-45°, so that the femoral condyle articular surface 110 between the second contact point B and the third contact point C can realize curvature transition, avoiding abnormal movement of the articular surface caused by sudden change of curvature.

[0043] Further, the difference between the third knee flexion angle and the second knee flexion angle is 10°-30°, so as to increase the degree of curvature change of the second articular surface portion 102, further ensure the stability of the knee joint in the high extension-flexion state, so that the first articular surface portion 101 can be provided with a larger radius of curvature, and further reduce the contact stress between the femoral condyle articular surface 110 and the tibial articular surface in the gait motion.

[0044] For example, in an embodiment of the present disclosure, the first contact point A corresponds to a knee flexion angle of 0°; the second contact point B corresponds to a knee flexion angle of 60°; and the third contact point C corresponds to a knee flexion angle of 75°. In the gait motion, the movement angle of the knee joint is generally within the range of 0-60°, and the pressure of the knee joint is generally the largest at this time. Therefore, the gait motion is the most important and the most frequent movement function of the knee joint, and the example embodiment can preferentially ensure that the femoral prosthesis 100 has the optimal performance in the gait.

[0045] For example, in another embodiment of the present disclosure, the first contact point A corresponds to a knee flexion angle of 0°; the second contact point B corresponds to a knee flexion angle of 60°; and the third contact point C corresponds to a knee flexion angle of 90°. In this way, the difference between the two end values of the second knee flexion angle range is 30°, which is conducive to the femoral condyle articular surface 110 to be provided with more curved surfaces with gradually changing curvature between the second contact point B and the third contact point C, and further conducive to more gently realizing the curvature transition; also conducive to increasing the first radius of curvature R1, and further improving the contact area between the femoral prosthesis 100 and the tibial articular surface in the gait motion, reducing the contact stress, and improving the service life of the femoral prosthesis 100.

[0046] For example, in another embodiment of the present disclosure, the knee flexion angle θ1 of the first contact point A is 0°; the knee flexion angle θ2 of the second contact point B is 50°; and the knee flexion angle θ3 of the third contact point C is 60°.

[0047] The second articular surface portion 102 includes a plurality of curved surfaces 111 with radii of curvature gradually decreasing from the front end to the rear end in the sagittal plane. Correspondingly, in the sagittal plane, the second articular surface portion 102 can present a plurality of curves with radii of curvature gradually decreasing from the front end to the rear end.

[0048] For example, as shown in FIG. 2, the second articular surface portion 102 includes a plurality of curved surfaces 111 with radii of curvature gradually decreasing from the front end to the rear end in the sagittal plane. Figure 1As shown, in the sagittal plane, the femoral condylar articular surface 110 also has a fourth contact point D and a fifth contact point E between the second contact point B and the third contact point C, wherein the curved surface 111 between the second contact point B and the fourth contact point D has a third radius of curvature R3, the curved surface 111 between the fourth contact point D and the fifth contact point E has a fourth radius of curvature R4, and the curved surface 111 between the fifth contact point E and the third contact point C has a second radius of curvature R2. The first radius of curvature R1, the third radius of curvature R3, the fourth radius of curvature R4, and the second radius of curvature R2 decrease in turn.

[0049] Optionally, the radius of curvature of the curved surface 111 at the last end of the second articular surface portion 102 is the second radius of curvature, and the difference between the radii of curvature of two adjacent curved surfaces 111 can be determined according to the difference between the first radius of curvature R1 and the second radius of curvature R2; the greater the difference between the first radius of curvature R1 and the second radius of curvature R2, the greater the difference between the radii of curvature of two adjacent curved surfaces 111; conversely, the smaller the difference between the first radius of curvature R1 and the second radius of curvature R2, the smaller the difference between the radii of curvature of two adjacent curved surfaces 111. Of course, the difference between the radii of curvature of two adjacent curved surfaces 111 can also be determined according to the number of curved surfaces 111 of the femoral condylar articular surface 110 between the second contact point B and the third contact point C; the greater the number of curved surfaces 111 of the femoral condylar articular surface 110 between the second contact point B and the third contact point C, the smaller the difference between the radii of curvature of two adjacent curved surfaces 111; conversely, the smaller the number of curved surfaces 111 of the femoral condylar articular surface 110 between the second contact point B and the third contact point C, the greater the difference between the radii of curvature of two adjacent curved surfaces 111.

[0050] In an embodiment of the present disclosure, in the sagittal plane, the difference between the radii of curvature of two adjacent curved surfaces 111 is not greater than 1 mm, so as to avoid abnormal movement of the articular surface caused by too large difference between the radii of curvature of two adjacent curved surfaces 111.

[0051] It can be understood that the angles of each curved surface 111 in the sagittal plane in the second articular surface portion 102 can be the same or different, as long as the difference between the radii of curvature of two adjacent curved surfaces 111 is kept within a reasonable range to avoid joint instability.

[0052] In an embodiment of the present disclosure, the ratio of the first radius of curvature to the second radius of curvature can be 1.3-2.1. The smaller the ratio of the first radius of curvature to the second radius of curvature, the smaller the change in the radius of curvature, which is beneficial to avoid abnormal movement of the articular surface caused by too large change in the curvature of the second articular surface portion 102; the larger the ratio of the first radius of curvature to the second radius of curvature, the larger the first radius of curvature, which is beneficial to increase the contact area of the articular surface under gait movement and reduce the wear of the joint prosthesis caused by frequent gait movement.

[0053] Further, the ratio of the first radius of curvature to the second radius of curvature is 1.5-1.9.

[0054] Further, the ratio of the first radius of curvature to the second radius of curvature is 1.5-1.9.

[0055] Most preferably, the ratio of the first radius of curvature to the second radius of curvature is 1.55-1.65.

[0056] Optionally, in the sagittal plane, the femoral condyle articular surface 110 has 2-6 curved surfaces 111 between the second contact point B and the third contact point C. In this way, different curved surfaces 111 are provided with different radii of curvature, which can achieve a smooth transition of the femoral condyle articular surface 110 from the first radius of curvature R1 to the second radius of curvature R2, and inhibit abnormal movement of the articular surface caused by sudden change in curvature.

[0057] Optionally, the femoral prosthesis 100 of the present disclosure can further include a resection surface 120 for connecting with the femur, and one or more fixation posts 130 can be arranged on the resection surface 120 to achieve fastening connection and positioning of the femoral prosthesis 100 with the femur.

[0058] The embodiment of the present disclosure also provides a knee joint prosthesis, which includes any one of the femoral prostheses 100 described in the above-described femoral prosthesis embodiments. The knee joint prosthesis can be a posterior cruciate ligament-preserving knee joint prosthesis and a posterior stabilized knee joint prosthesis or other types of knee joint prostheses. Since the knee joint prosthesis has any one of the femoral prostheses 100 described in the above-described femoral prosthesis embodiments, it has the same beneficial effects, which will not be described herein again.

[0059] Optionally, as shown in Figure 2 the knee joint prosthesis of the present disclosure further includes a tibial base 300 connected with the tibia, and a tibial spacer 200 located between the femoral prosthesis 100 and the tibial base 300, the upper surface of the tibial spacer 200 is articulately connected with the femoral condyle articular surface 110 of the femoral prosthesis 100, and the lower surface of the tibial spacer 200 can be rotatably connected with the tibial base 300 or fixedly connected with the tibial base 300.

[0060] It should be appreciated that the present disclosure is not limited to the details of construction and arrangement of parts set forth in the specification. The present disclosure is capable of other embodiments and of being practiced or being carried out in various ways. Variations and modifications of the foregoing are within the scope of the present disclosure. It should be understood that the present disclosure fully encompasses all combinations of two or more individual features set forth herein and / or in the appended claims. All these different combinations are considered to be within the scope of the present disclosure. The embodiments of the present disclosure as described are to be used as illustrative examples only and are not intended to limit the scope of the present disclosure in any way.

Claims

1. A femoral prosthesis, characterized in that, The femoral prosthesis includes a medial condyle and a lateral condyle, the medial condyle and the lateral condyle respectively having a femoral condyle articular surface for abutting against the tibial articular surface, the tibial articular surface including a natural meniscus, a tibial implant or a padding implant for abutting against the femoral prosthesis; The femoral condyle joint surface has a first articular surface portion for abutting against the tibial joint surface within a first knee flexion angle range, and a second articular surface portion for abutting against the tibial joint surface within a second knee flexion angle range; The first knee flexion angle ranges from the first knee flexion angle to the second knee flexion angle; the second knee flexion angle ranges from the second knee flexion angle to the third knee flexion angle; wherein, the first knee flexion angle is any knee flexion angle between -20° and 0°, the second knee flexion angle is any knee flexion angle between 50° and 60°, and the third knee flexion angle is any knee flexion angle between 60° and 90°, and the third knee flexion angle is greater than the second knee flexion angle; The sagittal plane of the first joint surface portion has a single first radius of curvature, and the radius of curvature of the sagittal plane of the second joint surface portion decreases from the front end to the rear end. The difference between the third knee flexion angle and the second knee flexion angle is 10°~30°; The second joint surface portion includes a plurality of curved surfaces with successively decreasing radii of curvature in the sagittal plane from the front end to the rear end; the radius of curvature of the curved surface located at the rear end of the second joint surface portion is the second radius of curvature, and the ratio of the first radius of curvature to the second radius of curvature is 1.3 to 2.

1.

2. The femoral prosthesis according to claim 1, characterized in that, The first knee flexion angle is 0°; the second knee flexion angle is 60°; and the third knee flexion angle is 75°.

3. The femoral prosthesis according to claim 1, characterized in that, The difference in the radius of curvature of any two adjacent curved surfaces in the sagittal plane is no greater than 1 mm.

4. The femoral prosthesis according to claim 1, characterized in that, The ratio of the first radius of curvature to the second radius of curvature is 1.5-1.

9.

5. The femoral prosthesis according to claim 4, characterized in that, The ratio of the first radius of curvature to the second radius of curvature is 1.5-1.

7.

6. A knee joint prosthesis, characterized in that, Includes the femoral prosthesis as described in any one of claims 1 to 5.

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