WO1999034755A1

WO1999034755A1 - Knee prosthesis

Info

Publication number: WO1999034755A1
Application number: PCT/FR1998/002924
Authority: WO
Inventors: Philippe Legay
Original assignee: Euro . Medic
Priority date: 1997-12-31
Filing date: 1998-12-31
Publication date: 1999-07-15
Also published as: CN1285953A; FR2773059A1; FR2773059B1; CN1143352C

Abstract

The invention concerns a modular knee prosthesis comprising a metal tibial seat (T1 to T8), a plastic tibial plateau (PM1, PF1, PM2, PF2), a plastic kneecap and a metal femoral prosthesis (F1 to F8). The tibial seat (T1 to T8) comprises a plate with a rear outline defining a first planar support surface for receiving the tibial plateau and a second raised support surface for forming first positioning means for the tibial plateau. Second positioning means for the tibial plateau are formed in the plate front central portion and means are arranged on the plate lower face for receiving a tibial insertion wedge. The tibial plateau (PM1, PF1, PM2, PF2) has a planar main lower face co-operating with the tibial seat first support surface, an indentation formed at the plateau rear lower part for defining a planar raised lower surface co-operating with the tibial seat second planar raised support surface, and a main upper surface comprising two cups. The femoral prosthesis (F1 to F8) comprises a trochlea with large radius of curvature in the medio-lateral direction and a regular radius of curvature in the antero-posterior coil.

Claims

17 CLAIMS

1. Knee prosthesis, comprising a metal tibial seat (100), a plastic tibial plate (210; 220), a plastic ball joint (400) and a metal femoral prosthesis (300), characterized in that the tibial seat (100) comprises a plate (1 10) having a posterior contour (112) essentially in the shape of a W and defining a first planar bearing surface (111) for receiving the tibial plateau (210; 220) and a second surface raised flat support (113) parallel to the first support surface (1 1 1) and formed on an extra thickness (120) in the vicinity of the posterior contour (112) of the plate (1 10) by providing a groove (125 ) in the anterior face of the extra thickness (120), to form first means for positioning the tibial plateau (210; 220), second means (121) for positioning the tibial plateau (210; 220) formed in the anterior central part of the plate (1 10) and means (127) arranged on the underside of the plate (110) to receive a keel (129) for tibial insertion, in that the tibial plate (210; 220) has an outline (208; 238) essentially in the form of a bean, a flat main lower face (219; 229) cooperating with the first bearing surface (1 1 1) of the tibial base (100), a notch (209; 239) formed at the lower rear part of the plate (210; 220) to define a raised planar lower surface (219a; 229a) cooperating with the second raised planar support surface (1 13) of the tibial base ( 100), and a main upper face comprising two bowls (212, 213; 222, 223) constituted by portions of spheres with large radius of curvature which form raised front parts (205, 206; 235, 236); in that the femoral prosthesis (300) has an anterior or trochlated face (310) with a wide radius of curvature in the medio-lateral direction and with a regular radius of curvature in the direction of the anteroposterior winding, of the first and second condyles (302, 303) consisting of portions of spheres congruent with the spherical cups (212, 213; 222, 223) of the tibial plateau (210; 220) and defining between them a wide intercondylar notch (350), and means (305 ) arranged on the upper face of the lo

central part of the femoral prosthesis (300) in front of the first and second condyles (302, 303) to receive a femoral keel (320; 520); and in that the patella (400) has a dome (401) with a radius of curvature identical to the wide radius of curvature of the trochlea (310) of the femoral prosthesis (300).

2. Prosthesis according to claim 1, characterized in that the second positioning means (121, 130) of the tibial plateau (210; 220) are formed peripherally in the anterior central part of the plate (1 10) and cooperate with an anterior notch (21 1; 221) of the tibial plateau (210; 220), the shape of which contributes to defining the fixed or mobile character of said tibial plateau (210; 220).

3. Prosthesis according to claim 1 or claim 2, characterized in that the tibial plate (210) is held in a fixed position on the tibial seat (100) on the one hand using the second positioning means (121 , 130) engaged in a narrow vertical notch (21 1) formed at the front part of the plate (210) and on the other hand using the notch (209) formed at the lower rear part of the plate (210) so as to abut against the extra thickness (120) formed in the tibial base (100) by engaging in said groove (125) formed in the front face of the extra thickness (120).

4. Prosthesis according to claim 1 or claim 2, characterized in that the tibial plateau (220) disposed on the tibial seat (100) comprises a wide vertical notch (221) with an arcuate profile formed at the front of the plate (220) and a notch (239) formed recessed at the lower rear part of the plate (220) so as to be able to present medio-lateral displacements (d _M ), an anteroposterior displacement (d _ap ) and rotational movements (α, and α ₂ ) relative to a central axis peφendicular to the flat underside of the tibial plateau, the movements being limited by the second positioning means (121, ι 30) and by the extra thickness (120) of the tibial base (100) provided with the groove (125) formed in the anterior face of the extra thickness (120).

5. Prosthesis according to any one of claims 1 to 4, characterized in that, in the absence of a femoral anchoring keel (320) or tibial (129), the knee prosthesis is symmetrical with respect to a plane (aa ';bib',; b ₂ b '₂;ce') peφendicular to the medio-lateral direction.

6. Prosthesis according to any one of claims 1 to 5, characterized in that the main upper face of the tibial plateau (210; 220) forms a central dome (214; 224) hollowed out at its rear part so as to have a slope rear (215; 225).

7. Prosthesis according to any one of claims 1 to 6, characterized in that the femoral prosthesis (300) comprises on its internal faces recessed parts (308, 309, 31 1, 312) and fixing means (306,307 ) arranged on at least two recessed parts (308, 309) formed on the first and second condyles (302, 303).

8. Prosthesis according to claim 7, characterized in that the femoral prosthesis (300) further comprises a third removable condyle (304) disposed between the first and second condyles (302, 303), on the internal side thereof, the third condyle (304) comprising projecting parts (341 to 344) and orifices (316, 317) cooperating respectively with the recessed parts (308, 309, 311, 312) and the fixing means (306,307) arranged on the faces internal of the femoral prosthesis (300).

9. Prosthesis according to any one of claims 1 to 8, characterized in that the keel (129) of tibial insertion has an asymmetrical shape with a first main face (131) parallel to an axis (aa ') peφendicular to the flat bearing surface (1 1 1) of the plate (1 10) of the tibial base (100) and a second main face (132) forming an angle of approximately 5 ° relative to said axis (aa '), the keel (129) being able to be positioned in the means (127) for receiving the keel formed on the underside of the plate (110) in such a way that during assembly of the prosthesis the front face of the keel (129) is constituted optionally by the first (131) or second (132) main face.

10. Prosthesis according to claim 9, characterized in that the means (127) for receiving the keel formed on the underside of the plate (110) of the tibial base (100) comprise a hemispherical part in which is formed a blind hole (128) for receiving a pin (128a) for positioning the keel (129).

1 1. Prosthesis according to any one of claims 1 to 10, characterized in that it comprises a removable femoral keel (320) 20

having an axis inclined about 7 ° relative to normal (d, d ') to a base surface provided with an anchoring cavity (315) cooperating with the fixing means (305) arranged on the upper face of the central part of the femoral prosthesis (300), so that the removable femoral keel (320) can be positioned during mounting on the femoral prosthesis (300) with a freely chosen inclination to the right or to the left.

12. Prosthesis according to any one of claims 1 to 11, characterized in that the trochlea (310) of the femoral prosthesis (300) has a radius of curvature in the medio-lateral direction of between approximately 80 and 100 mm.

13. Prosthesis according to claim 4, characterized in that the tibial plateau (220) is disposed relative to the tibial base (100) so as to have rotational displacements (α, and α) maximum share and another from an average position, of the order of 15 °.

14. Prosthesis according to any one of claims 1 to 13, characterized in that it comprises a tibial seat (100) chosen from a set of tibial seats of different sizes (T] to T ₈ ) in number N between 6 and 12, a tibial plate (210, 220) chosen from a set of fixed tibial plates of different sizes and thicknesses (PF, PF ₂ ) in number n, between 10 and 20 or from a set of mobile tibial plates of different sizes and thicknesses (PMi, PM ₂ ) in number n ₂ between 10 and 20, and a femoral prosthesis (300) chosen from a set of femoral prostheses of different sizes (F] to F ₈ ) in number M between 6 and 12.

15. Prosthesis according to claim 14, characterized in that the numbers N, ni, n ₂ and M are respectively equal to 8, 10, 10 and 8.

16. Prosthesis according to claim 14 or claim 15, characterized in that the set of tibial seats of different sizes (T, to T ₈ ) is obtained from a tibial seat of maximum size T ₈ whose dimension ( ML) in the medio-lateral direction is around 85 mm and the dimension (AP) in the antero-posterior direction is around 55 mm.

17. Prosthesis according to any one of claims 14 to 16, characterized in that in the set of tibial bases of different sizes (Ti to T ₈ ), certain tibial bases differ from other tibial bases of different sizes only by only one dimension chosen from dimension (ML) 21

in the medio-lateral direction and among the dimension (AP) in the anteroposterior direction.

18. Prosthesis according to any one of claims 14 to 17, characterized in that the set of femoral prostheses of different sizes (F] to F ₈ ) is obtained from one or two basic parts defining a circle whose radius (R,) is between approximately 45 and 60 mm.

19. Prosthesis according to claim 7, characterized in that it comprises a module (500) of the femoral keel comprising a coφs (510) defining a hemispherical cavity, the coφs (510) being extended upwards by a keel proper ( 520) and being provided laterally at its base with projecting parts (531, 532, 534, 535) and orifices (556, 557, 555) cooperating respectively with the recessed parts (308, 309, 31 1, 312) and the fixing means (306, 307, 305) formed on the internal faces of the femoral prosthesis (300), and a femoro-tibial module (600) comprising a spherical head (610) intended to engage in the hemispherical cavity of the coφs (510) of the femoral keel module (500), and a base plate (620) provided with positioning means (601, 602) cooperating with said second means (121) for positioning the tibial plateau (210) and thirds positioning means (122) formed in the front central part of the s thickness (120) of the tibial base (100).

20. Prosthesis according to claim 9, characterized in that the means (127) for receiving the keel formed on the underside of the plate (110) of the tibial base (100) comprise a portion of first hemispherical appearance ( 133) provided with grooves (134) extended downwards by a truncated cone-shaped element (135) whose large base is connected to the grooved part, which has a slope of approximately 5 °, and which is provided with 'A blind hole (128) for receiving a pin (128a) for positioning the keel (129).