FR2839642A1

FR2839642A1 - Femoral section of knee prosthesis has screw fixed to hole in anterio-posterior wall to control flexion

Info

Publication number: FR2839642A1
Application number: FR0206008A
Authority: FR
Inventors: Philippe Mathias
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-05-16
Filing date: 2002-05-16
Publication date: 2003-11-21

Abstract

The femoral section for a knee prosthesis has a screw (8) or pin fixed to the femoral section behind the femoral condyle. The screw is placed along the transverse axis (7) spaced from the joint in a hole (4) or a threadable insert in the section of the prosthesis forming an anterio-posterior wall (3).

Description

presente par la prothese.presented by the prosthesis.

- 1 La presente invention concerne un nouveau type de prothese de genou appartenant a la categoric des protheses cites "unicompartimentale". C'est un implant chirurgical - 1 The present invention relates to a new type of knee prosthesis belonging to the category of prostheses cited "unicompartimentale". It is a surgical implant

demontable.demountable.

Les protheses actuelles de ce type ne reconstituent que partiellement les surface de glissement des condyles femoraux limitant la flexion en charge des genoux operes a Current prostheses of this type only partially reconstruct the sliding surface of the femoral condyles limiting the bending in load of the knees operated on.

en moyenne contre 175 en physiologic humaine. on average against 175 in human physiology.

Le present dispositif concerne uniquement la piece femorale, la piece tibiale etant The present device relates only to the femoral part, the tibial part being

supposee proche de l'existant, voire identique. assumes close to existing, even identical.

Les modes d/implantation actuels ne permettent pas une flexion totale du genou en The current implantation methods do not allow total knee flexion in

charge sans risque de descellement d'arrachement ou de casse de la prothese. load without risk of loosening of tearing or breakage of the prosthesis.

Le dispositif selon ['invention permet de fixer la prothese dans l'os d'une fac,on compatible avec les contraintes exercees sur le montage lors d'une flexion totale du The device according to the invention makes it possible to fix the prosthesis in the bone in a way that is compatible with the stresses exerted on the assembly during a total bending of the

genou en charge tout en permettant une eventuelle extraction ulterieure. knee in load while allowing a possible subsequent extraction.

Les materisux et techniques de fabrication vent les memes que ceux actuellement utilises par les fabricants pour ce type de prothese. Comme pour tous les modeles existants, celui-ci necessitera des outils de prise de gabarit, d'alignement et de preparation de l'os specifiques. Cette prothese sera posee, a ['exception de la mise en place de la vis (8), selon des protocoles comparables aux protocoles actuels Les dessins annexes illustrent ['invention: La figure 1 represente ['invention vue de The materials and manufacturing techniques are the same as those currently used by manufacturers for this type of prosthesis. As with all existing models, this will require tools for template taking, alignment and specific bone preparation. This prosthesis will be placed, with the exception of the installation of the screw (8), according to protocols comparable to current protocols. The annexed drawings illustrate the invention: FIG. 1 represents the invention seen from

3/4 avant et la figure 2 represente ['invention de profil. 3/4 front and Figure 2 represents the invention of the profile.

La prothese comprend, comme l'existant, une surface de glissement (1) biconvexe, homothetique au condyle femoral humain concerne (interne ou externe), a ['exception de la surface correspondante aux derniers degree de flexion (2) qui presente un rayon de courbure legerement inferieur aux courbures physiologiques et qui se prolonge The prosthesis comprises, like the existing one, a sliding surface (1) biconvex, homothetic to the human femoral condyle concerned (internal or external), with the exception of the surface corresponding to the last degrees of flexion (2) which presents a radius curvature slightly lower than the physiological curvatures and which extends

jusqu'a 180 de la reference horizontale (plateau (9)). up to 180 from the horizontal reference (plate (9)).

Les figures 1 et 2 representent la piece femorale pour un condyle externe. La courbe de la surface de glissement (1) et (2) pour un condyle interne serait legerement differente, dans le sens antero-posterieur (homothetique au condyle interne humain), Figures 1 and 2 show the femoral part for an external condyle. The curve of the sliding surface (1) and (2) for an internal condyle would be slightly different, in the antero-posterior direction (homothetic to the human internal condyle),

mais les constituents et les caracteristiques de la prothese resteraient les memes. but the constituents and characteristics of the prosthesis would remain the same.

Le plateau de contact avec l'os (9) donne la reference horizontale. Le contact avec l'os se prolonge par le plateau intermediaire (10) et le plateau posterieur (11) Le plateau horizontal (9) est porteur, comme existent, d'un plot d'insertion (5) qui peut etre soit vertical, soit incline vers ['avant, comme represente sur les figures 1 et 2, d'un angle pouvant atteindre jusqu'a 50 par rapport a la,verticale. Cet angle est presehte sur les figures 1 et 2.a 40 - 2 Le plateau (11) peut etre vertical, incline en arriere ou incline en avant. Dans tous les cas l'axe du plot d'insertion (5) et l'inclinaison du plateau (11) doivent former un angle divergent vers le haut ou vers le haut et ['avant, d'au moins 10 , ceci afin de faciliter I'eventuelle extraction ulterieure de la prothese. Les plateaux (11), (10) et (9) vent porteurs en leur centre d'un mur antero-posterieur The bone contact plate (9) gives the horizontal reference. The contact with the bone is extended by the intermediate plate (10) and the posterior plate (11) The horizontal plate (9) carries, as exist, an insertion pad (5) which can be either vertical, or tilt forward, as shown in Figures 1 and 2, at an angle of up to 50 relative to the vertical. This angle is shown in Figures 1 and 2.a 40 - 2 The plate (11) can be vertical, tilting back or tilting forward. In all cases the axis of the insertion pad (5) and the inclination of the plate (11) must form a divergent angle upwards or upwards and upwards, of at least 10, in order to facilitate any subsequent extraction of the prosthesis. The plates (11), (10) and (9) carry carriers in their center of an anteroposterior wall

(3) qui renforce la prothese dans les angles que ces plateaux forment entre eux. (3) which reinforces the prosthesis in the angles that these plates form between them.

Ce mur (3) prend naissance a la partie superieure du plateau (11). Ii est porteur d' u n trou (4) o u d' u ne pastille (en lieu et place du trou) faite d'u n materisu biocom patible, moins dur que la prothese et susceptible d'etre perce eUou taraude d'un seui geste et a travers l'os, une fois la prothese mise en place. Dans le cas d'une pastille, celle-ci est This wall (3) originates at the upper part of the plate (11). It has a hole (4) or a pellet (in place of the hole) made of a patent biocom material, less hard than the prosthesis and likely to be drilled or tapped with a single gesture and through the bone, once the prosthesis is in place. In the case of a tablet, this is

d'un diametre superieur au diametre de la vis (8) ou de la cheville qu'elle accueillera. of a diameter greater than the diameter of the screw (8) or of the plug which it will receive.

Ce trou (4) ou cette pastille est situee pres du bord antero-superieur du mur (3). Le mur avance depuis le plateau (11) vers ie teas et vers ['avant, jusquta ce que l'axe transversal (7) du trou (4) se situe en avant de ['insertion posterieure de la capsule articulaire, une fois la prothese mise en place. Le bord anterieur du mur (6) forme avec l'axe du plot d'insertion (5) un angle legerement divergent vers le haut ou vers le haut et ['avant afin de faciliter lteventuelle extraction ulterieure de la prothese. Le mur se prolonge avec une faible hauteur jusque sur le plateau (9), se confondant a son This hole (4) or this patch is located near the antero-superior edge of the wall (3). The wall advances from the plate (11) towards the teas and towards the front, until the transverse axis (7) of the hole (4) is located in front of the posterior insertion of the articular capsule, once the prosthesis in place. The front edge of the wall (6) forms with the axis of the insertion stud (5) a slightly divergent angle upwards or upwards and [before] in order to facilitate the possible subsequent extraction of the prosthesis. The wall extends with a small height up to the plate (9), merging with its

extremite anterieure avec le plot d'insertion (5). anterior end with the insertion stud (5).

L'etendue du mur (3) lui confere une fonction anti-rotation rendant inutile la The extent of the wall (3) gives it an anti-rotation function making the

presence d'un second plot comme existent. presence of a second pad as exist.

Le trou (4) ou la pastille est destine a recevoir une vis (8) ou une cheville traversant selon un axe transversal (7) le condyle femoral en avant de ['insertion posterieure la The hole (4) or the pellet is intended to receive a screw (8) or a dowel crossing along a transverse axis (7) the femoral condyle in front of the posterior insertion.

capsule articulaire.joint capsule.

La vis (8) ou la cheville est destine a recevoir et a transmettre a l'os les contraintes The screw (8) or the dowel is intended to receive and transmit stresses to the bone

exercees sur la prothese lors d'une flexion du genou en charge superieure a 120 . exerted on the prosthesis during a knee flexion under load greater than 120.

Selon une variante non illustree, le mur (3) peut se limiter a une paste ne stinserant que sur les plateaux intermediaires (10) et posterieur (11), voire uniquement sur le plateau posterieur (11), a condition toutefois que son bord anterieur (6) respecte la divergence d'avec l'axe du plot d'insertion (5) evoquee plus haut. Dans ce cas la fonction de renfort des angles formes par les plateaux entre eux peut etre assuree par deux petite murs lateraux distants de l'axe median, comme existent, ou ne pas etre assuree. Dans cette variante, si l'etendue du mur n'est pas suffsante pour assurer une According to a variant not illustrated, the wall (3) can be limited to a paste only stinserant on the intermediate plates (10) and rear (11), or even only on the rear plate (11), provided however that its front edge (6) respects the divergence from the axis of the insertion pad (5) mentioned above. In this case the reinforcement function of the angles formed by the plates between them can be provided by two small side walls distant from the median axis, as they exist, or not be provided. In this variant, if the extent of the wall is not sufficient to ensure a

fonction anti-rotation, la prothese peut porter 2 plots, corpme existent, au lieu d'un seul. anti-rotation function, the prosthesis can carry 2 studs, body available, instead of just one.

- 3- 3

Claims

1) Femoral piece of unicompartmental knee prosthesis intended to allow a total flexion of the knee under load, characterized in that it comprises a screw (8) or an ankle intended to secure said femoral piece behind the femoral condyle, said YiS (8 ) OR ankle being placed along the extra-articular transverse axis (7) of a hole (4) or of a threaded disc provided in a

part of the prosthesis consists of an anteroposterior wall (3).

2) femoral piece of unicompartmental prosthesis according to claim 1 characterized in that it comprises a sliding surface (1) whose part (2) useful in the last degree of flexion has a radius of curvature

- slightly lower than the physiological curvature.

3) femoral piece of unicompartmental prosthesis according to claim 1 characterized in that the pellet made of a biocompatible and tapping material has a larger diameter than that of the screw (8) or the dowel