FR2955482A1 - Prosthetic femoral component assembly for knee prosthesis, has condyles cooperating with tibial plate of knee prosthesis, where each condyle include exterior convex section defined by toric surfaces with radius of curvature - Google Patents

Abstract

The assembly has lateral condyles (3, 4) cooperating with a tibial plate of a knee prosthesis, where each condyle comprises an exterior convex section defined by toric surfaces with a circle arc generator, where radius of curvature (R2) of each toric surface is identical. An intercondylar passage (6) is defined laterally by a plane surface inclined with respect to each other along 10 degree environment. A central face is extended perpendicular to a mechanic femoral axis of a femur.

Description

The present invention relates to a range of femoral prosthetic components for knee prosthesis, and more particularly for total knee prosthesis. A total knee prosthesis comprises, in known manner, a tibial base intended to be fixed to the upper end of a tibia after partial resection thereof, a tibial plateau of plastic material, such as polyethylene, intended to take support on the tibial base, and a prosthetic femoral component intended to rest on the tibial plateau and to be attached to the lower end of a femur, after resection thereof.

The femoral prosthetic components are developed in different sizes to cover the maximum of needs according to the morphologies of the patients. Surgeons have prosthetic femoral components with cement fixation or cementless fixation.

In addition, the prosthetic femoral components also exist in so-called anatomical version which imposes a range comprising left femoral prosthetic components, that is to say, intended to be fixed on a left femur, and right femoral prosthetic components, it is that is, intended to be fixed on a right femur.

There are also prosthetic femoral components with asymmetrical condyles, that is to say having non-parallel internal and external condyles, prosthetic femoral components with condyles formed by portions of the toric surface, or prosthetic femoral components with condyles. little or very congruent in the anteroposterior plane.

In order to ensure optimal operation of a total hip prosthesis, it is necessary to provide, for each type and size of femoral component, a suitable tibial plateau. This results in a large number of elements to be made available to the surgeon, which increases the storage and makes the surgical procedure more complex. The present invention aims to remedy these disadvantages. The technical problem underlying the invention therefore consists in providing a range of prosthetic femoral components which makes it possible to reduce the number of parts to be made available to surgeons. To this end, the invention relates to a range of femoral prosthetic components of different sizes for knee prosthesis of the type comprising two lateral condyles arranged to cooperate with a tibial plateau of a knee prosthesis, and a trochlear part, characterized in that that each condyle of each prosthetic femoral component has a convex outer profile delimited by at least one ring-shaped generatrix with an axis of arc and an axis extending substantially parallel to the mediolateral direction, and in that the toric surfaces delimiting the condyles of all the femoral components have arcuate generatrices having substantially identical radii of curvature. These arrangements allow the realization of a range of tibial trays and a range of femoral components in which each femoral component is adapted to be used with each tibial plateau. As a result, the number of parts to be made available to surgeons is greatly reduced, which facilitates the surgical procedure.

In addition, these arrangements allow the surgeon to independently choose the femoral component having the size resulting in the minimum bone cutting, thus the minimum bone loss, and the tibial plateau ensuring maximum coverage of the proximal tibial cut to ensure satisfactory stability of the tibial plateau.

Advantageously, for all the femoral components, the centers of the arcuate generatrices of the toric surfaces delimiting the lateral condyles have substantially identical spacings. Advantageously, the centers of the arcuate generatrices of the toric surfaces delimiting the lateral condyles of all the femoral components have a spacing of approximately 45 mm. Preferably, for each femoral component, the centers of the arcuate generatrices of the toric surfaces delimiting the lateral condyles are arranged symmetrically with respect to the anteroposterior plane. Preferably, the toric surfaces delimiting the lateral condyles of a femoral component have substantially identical radii of revolution. Advantageously, the arcuate generatrices of the toric surfaces delimiting the lateral condyles of all the femoral components have a radius of curvature of between 60 and 80 mm, and preferably of approximately 70 mm.

Preferably, the radius of revolution of a toric surface of a condyle varies homothetically between two successive sizes of femoral components. The ratio of the rays of revolution between two successive sizes of prosthetic femoral components is advantageously between 1.03 and 1.07, and preferably equal to 1.05. According to one embodiment of the invention, the toric surfaces delimiting the condyles of all the femoral components extend angularly over an angle greater than 100 °, and preferably about 120 °. Advantageously, when a femoral component is positioned on a femur and the knee is in the extended position, each toric surface extends angularly at a first angle α in the anterior direction relative to the contact zone of the femoral component on the plateau. tibial, and on a second angle 3 in a posterior direction relative to this contact zone, and in that the first and second angles a, 3 of all the femoral components are respectively substantially identical. Preferably, the angles α of all the femoral components are substantially equal to 25 °, and the angles 3 of all the femoral components are substantially equal to 95 °. Preferably, the outer surface of the trochlear portion of each femoral component has a trochlear groove defining a trochlear path, the trochlear groove of each femoral component being formed by a toric surface portion. Preferably, the trochlear groove of each femoral component is inclined relative to the bearing plane of the femoral component on the tibial plateau, in the position of extension of the knee, of an inclination angle, the angles of inclination of the trochlean grooves of all the femoral components being substantially identical. Advantageously, the trochlear groove of each femoral component is inclined relative to the bearing plane of the femoral component on the tibial plateau, in the extended position of the knee, with an inclination angle of about 84 °. Advantageously, each prosthetic femoral component has an intercondylar passage formed between the lateral condyles, the intercondylar passages of all the femoral components having substantially identical dimensions in the mediolateral direction.

Advantageously, the intercondylar passage of each femoral component is delimited laterally by two plane surfaces inclined with respect to each other so that the width of the intercondylar passage is greater posteriorly than before. These arrangements allow rotation of the femoral component on the tibial plateau during flexion movements of the knee. Preferably, the intercondylar passage of each femoral component is delimited laterally by two plane surfaces inclined relative to each other by an angle of about 10 °. Preferably, each femoral component comprises a concave inner portion having a general U shape and intended to be fixed to the lower end of a femur, after resection thereof, the concave inner portion being delimited by a surface formed by at least three support faces intended to cooperate with the femur, namely a central face delimiting the base of the U and two posterior and posterior faces delimiting the branches of the U. According to one embodiment of the invention, the length of the an anterior face and / or a posterior face varies homothetically between two successive sizes of femoral components. The ratio of the lengths of the anterior and / or posterior faces between two successive sizes of prosthetic femoral components is advantageously between 1.03 and 1.07, and preferably equal to 1.05.

Preferably, the anterior and posterior faces of each femoral component extend along two inclined planes relative to each other by an angle of approximately 10 °. According to one characteristic of the invention, the central face of each femoral component comprises two internal and external anchoring studs of substantially parallel axes and extending substantially perpendicularly to the central face, the anchoring studs of each femoral component being arranged symmetrically with respect to the antero-posterior plane. Preferably, the inner and outer anchoring studs of all the femoral components have substantially identical spacings, and preferably identical to the center-to-center distances of the arcuate generatrices of the toric surfaces delimiting the lateral condyles. Advantageously, each anchor pad is frustoconical. Preferably, the external anchor pad has a height greater than that of the internal anchor pad.

The anteroposterior crowding preferably varies homothetically between two successive sizes of femoral components. The ratio of anteroposterior crowding between two successive sizes of prosthetic femoral components is advantageously between 1.03 and 1.07, and preferably equal to 1.05. According to one embodiment of the invention, each femoral component comprises a postero-stabilization bar connecting the lateral condyles substantially at their free end. Preferably, each postero-stabilization bar extends in a mediolateral direction. Advantageously, the axis of each postero-stabilization bar extends substantially in the same plane as the ends of the toric surfaces of the lateral condyles opposite to the trochlear part. In any case the invention will be better understood with the aid of the description which follows with reference to the attached schematic drawing showing, by way of non-limiting example, an embodiment of this range of femoral components.

Figure 1 is an anterior view of a femoral component belonging to the range according to the invention. Figure 2 is a sectional view along the line II-II of Figure 1. Figure 3 is a perspective view of the femoral component of figurel.

Figure 4 is a top view of the femoral component of Figure 1. Figure 5 is a rear view of the femoral component of Figure 1. Figure 6 is a top view of six femoral prosthetic components superimposed belonging to the range of the invention. Figure 7 is a side view of the femoral components of Figure 1.

The range of prosthetic femoral components according to the invention may comprise for example eight femoral components of different sizes. As shown more particularly in FIG. 3, each femoral component 2 comprises an internal condyle 3 and an external condyle 4 intended to slide on a tibial plateau of a knee prosthesis, a trochlear portion 5 extending from the inner and outer condyles, and an intercondylar passage 6 formed between the inner and outer condyles. Each femoral component 2 advantageously comprises a convex and smooth outer surface. As shown more particularly in Figure 2, each femoral component 2 has a concave inner portion 7 having a general shape of U and intended to be fixed to the lower end of a femur, after resection thereof. The concave inner portion 7 is delimited by a surface formed by five bearing faces intended to cooperate with the femur, namely a central face 8 delimiting the base of the U, two posterior 9 and front 11 surfaces delimiting the branches of the U, and two posterior intermediate faces 12 and anterior 13 respectively connecting the central face 8 and the two posterior 9 and front faces 11. The central face 8 extends substantially perpendicular to the femoral femoral axis A of the femur and the posterior face 9 extends substantially parallel to the mechanical femoral axis A, when the femoral component 2 is positioned on the femur. Preferably, the anterior face 11 and posterior 9 of each femoral component extend in two inclined planes relative to each other by an angle of about 10 °. According to one characteristic of the invention, the lengths of the anterior and posterior surfaces 9 and 9 vary homothetically between two successive sizes of femoral components. The ratio of the lengths of the anterior and posterior faces between two successive sizes of prosthetic femoral components is advantageously between 1.03 and 1.07, and preferably equal to 1.05.

As shown in FIG. 4, the central face 8 of each femoral component 2 comprises two internal and 14 external frustoconical anchoring studs 15 of parallel axes and extending perpendicularly to the central face. The two studs 14, 15 are intended to be received in two bores in the femur perpendicular to the distal femoral cut.

The anchoring studs 14, 15 of each femoral component 2 are arranged symmetrically with respect to the anteroposterior plane P. Preferably, the internal and external anchoring studs of all the femoral components have an identical spacing E 1, about 45 mm. Advantageously, the internal anchoring stud 14 has a height less than that of the external anchor pad 15. Each anchor pad 14, 15 further has a taper of between about 3 ° and 6 ° to allow compression bone during the penetration of the pads in the corresponding bores, and preferably about 5 °. In addition, each anchor pad 14, 15 has a smooth outer surface to prevent a biological fixation of the femur that would complicate a possible extraction of the femoral component.

Two sectional planes are shown in FIG. 4, namely a sagittal section plane P1 passing through the medial part of the inner condyle 3 and a sagittal section plane P2, parallel to the sagittal section plane P1, passing through the middle portion of the external condyle 4. It should be noted that the profile of the internal condyle 3 in the plane P1 is identical to the profile of the internal condyle 4 in the plane P2. Each condyle 3, 4 has a convex exterior profile delimited by a first toric surface 16 having an arcuate generatrix and an axis extending parallel to the mediolateral direction, and second toroidal surface 17 tangent to the first portion and radius of revolution lower. The first toric surfaces 16 of the inner and outer condyles are advantageously arranged symmetrically with respect to the anteroposterior plane P. The first toric surfaces 16 of the inner and outer condyles of a femoral component have identical rays of revolution R1, and extend angularly over an angle greater than 100 °, and preferably about 120 °. As shown in FIG. 2, when a femoral component is positioned on a femur and the knee is in an extended position (i.e. with 0 ° of flexion), each toric surface 16 extends angularly over an angle α of about 25 ° in the anterior direction relative to the contact area C of the femoral component 2 on the tibial plateau, and at an angle of about 95 ° in a posterior direction with respect to this contact zone. According to a characteristic of the invention, the angles a and 13 of all the femoral components belonging to the range are respectively identical. According to another characteristic of the invention, the O-surfaces 16 delimiting the condyles 3, 4 of all the femoral components belonging to the range have arcuate generatrices having identical radii of curvature R2. Advantageously, the arcuate generatrices of all the femoral components have a radius of curvature R2 between 60 and 80 mm, and preferably about 70 mm. According to yet another feature of the invention, the radius of revolution R1 of a toric surface 16 of a condyle varies homothetically between two successive sizes of femoral components. The ratio of the rays of revolution R1 of the toric surfaces 16 between two successive sizes of prosthetic femoral components is advantageously between 1.03 and 1.07, and preferably equal to 1.05. Advantageously, for all the femoral components, the centers Oi and Oe of the arcuate generatrices of the toric surfaces delimiting the inner and outer condyles have an identical spacing E2, preferably of approximately 45 mm. Preferably, for each femoral component, the centers O 1 and O e of the arcuate generatrices of the toric surfaces delimiting the lateral condyles are arranged symmetrically with respect to the anteroposterior plane. Advantageously, the trochlear portion 5 has an outer profile substantially arcuate in the planes P1 and P2. As shown more particularly in FIGS. 4 and 5, the outer surface of the trochlear portion 5 of each femoral component 2 comprises a trochlear groove 21 defining a trochlear path. The trochlear groove 21 of each femoral component is formed by an outwardly directed concave toroidal surface portion extending substantially in an anteroposterior direction. In a mediolateral direction, the trochlear groove 21 of each femoral component has a single radius of curvature of between 18 and 22 mm, and preferably about 20 mm. Preferably, the trochlear groove 21 of each femoral component 2 is inclined with respect to the bearing plane Pa of the femoral component on the tibial plateau, in the position of extension of the knee, with an angle of inclination of about 84. °. According to one characteristic of the invention, the anteroposterior bulk preferably varies homothetically between two successive sizes of femoral components. The ratio of anteroposterior congestion between two successive sizes of prosthetic femoral components is advantageously between 1.03 and 1.07, and preferably equal to 1.05. Each femoral component comprises a post-stabilization bar 22 connecting the inner and outer condyles substantially at their free end. Preferably, each posterior stabilization bar 22 extends in a mediolateral direction. It goes without saying that the invention is not limited to the sole embodiment of this range of femoral components, described above. above as an example, it encompasses all the variants.

Claims (14)

REVENDICATIONS1. A range of prosthetic femoral components (2) of different sizes for knee prosthesis of the type comprising two lateral condyles (3, 4) arranged to cooperate with a tibial plateau of a knee prosthesis, and a trochlear portion (5), characterized in that that each condyle (3, 4) of each prosthetic femoral component (2) has a convex outer profile delimited by at least one toric surface (16) with a generatrix in an arc of a circle and an axis extending substantially parallel to the direction mediolateral, and in that the O-surfaces (16) defining the condyles (3, 4) of all the femoral components (2) have arcuate generatrices having substantially identical radii of curvature (R2). 2. Range according to claim 1, characterized in that, for all the femoral components, the centers (Oi, 0e) generatrices arcuate ring surfaces (16) delimiting the lateral condyles (3, 4) have spacings (E2) substantially identical. 3. Range according to claim 1 or 2, characterized in that, for each femoral component, the centers (Oi, 0e) of the arcuate generatrices of the toric surfaces (16) delimiting the lateral condyles (3, 4) are arranged symmetrically with respect to the anteroposterior plane (P). 4. Range according to one of claims 1 to 3, characterized in that the radius of revolution (R1) of a toric surface (16) of a condyle (3, 4) varies homothetically between two successive sizes of femoral components. 5. Range according to one of claims 1 to 4, characterized in that the O-surfaces (16) defining the condyles (3, 4) of all the femoral components extend angularly over an angle greater than 100 °, and preferably about 120 °. 35 6. Range according to one of claims 1 to 5, characterized in that, when a femoral component is positioned on a femur and the knee is in the extended position, each toric surface (16) extends angularly on a first angle (a) in the anterior direction with respect to the contact zone of the femoral component on the tibial plateau, and on a second angle (R) in a posterior direction with respect to this contact zone, and in that the first and second angles (a, 3) of all the femoral components are substantially identical, respectively. 7. Range according to one of claims 1 to 6, characterized in that the outer surface of the trochléenne part (5) of each femoral component (2) comprises a trochléenne groove (21) defining a trochlear path, the trochléen groove (21) each femoral component being formed by a toric surface portion. 8. Range according to claim 7, characterized in that the trochlear groove (21) of each femoral component (2) is inclined relative to the bearing plane (Pa) of the femoral component on the tibial plateau, in extended position knee, an inclination angle (y), the inclination angles of the trochlear grooves (21) of all the femoral components being substantially identical. 9. Range according to one of claims 1 to 8, characterized in that each prosthetic femoral component (2) has an intercondylar passage (6) formed between the lateral condyles (3, 4), the intercondylar passages (6) of all the femoral components having substantially identical dimensions in the mediolateral direction. 10. Range according to claim 9, characterized in that the intercondylar passage (6) of each femoral component is delimited laterally by two flat surfaces inclined relative to each other by an angle of about 10 °. 11. Range according to one of claims 1 to 10, characterized in that each femoral component comprises a concave inner portion (7) having a general shape of U and intended to be fixed to the lower end of a femur, after resection thereof, the concave inner portion being delimited by a surface formed by at least three faces of appuidestinées to cooperate with the femur, namely a central face (8) defining the base of the U and two posterior faces (9) and anterior (11) delimiting the branches of the U. 12. Range according to claim 11, characterized in that the length of a front face (11) and / or a rear face (9) varies homothetically between two successive sizes of femoral components. 13. Range according to one of claims 10 to 12, characterized in that the central face (8) of each femoral component (2) comprises two internal anchoring studs (14) and outer (15) of substantially parallel axes and extending substantially perpendicular to the central face, the anchoring studs (14, 15) of each femoral component (2) being symmetrically disposed with respect to the anteroposterior plane (P). 14. Range according to claim 13, characterized in that the internal and external anchoring studs of all the femoral components have substantially identical spacings (E1), and preferably identical to the center distances (E2) of the generatrices in an arc. circle of the toric surfaces delimiting the lateral condyles.