FR2838330A1 - Knee joint prosthesis tibial assembly has base designed to receive fixed or moving plate - Google Patents

Abstract

The tibial assembly, made with a base (1) to receive a plate that interacts with the condyle sections of a femoral implant, has the base shaped to receive either a fixed or moving plate. It has an anterior stabilising recess (1a) to receive a matching boss on the underside of a fixed plate, a posterior hole (1b) for a fixed plate screw or a moving plate stabilising pin, and an edge (1c) shaped to guide a moving plate. The fixed plate has a cavity to receive the screw head, the screw hole being located inside a guide boss (1d) for either a fixed or moving plate.

Description

(3). . The invention relates to the technical sector of implants

  orthopedic and relates more particularly to a joint prosthesis

knee.

  There are many types of knee joint prostheses

  whose specific characteristics depend on the pathological case to be treated.

  Generally, a knee joint prosthesis includes a tibial implant and a femoral implant. The tibial implant consists of a tibial base, generally metallic, receiving an insert or tibial plate, generally made of polyethylene. The tibial plateau cooperates

  with the condylar pads of the femoral implant.

  There are, moreover, total knee prostheses in which the femoral and tibial implants are mechanically linked with capacity for articulation and sometimes rotation. We can also cite the so-called "slip" prostheses o the femoral and tibial implants, after

  impaction, are not related to each other.

  Whatever the type of prosthesis, the tibial plate can be mounted on the corresponding tibial base, in a fixed manner, or else in a mobile manner with multidirectional displacement capacity. The choice of a tibial implant, with a fixed plate or with a mobile plate, obviously depends on the pathological cases to be treated, and in particular, for example, on the conservation or not of the posterior crusader. Obviously, the choice of a fixed platform or a mobile platform can have a very important impact

on the outcome of the intervention.

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  At this day, there are either tibial implants with a fixed plate, or tibial implants with a movable plate, with, for each case, a specific installation material. In other words, the surgeon does not have the possibility, during the operation, to choose either a fixed plate or a mobile plate and to use the same instrument. However, it is hardly conceivable for the surgeon to have at his disposal either a knee prosthesis with a fixed plate, or a knee prosthesis with a movable plate, with the ancillary corresponding to each of the types of prosthesis. This would result in a costly and difficult operation with

  risks of significant errors, at the time of the intervention.

  The object of the invention is to remedy these drawbacks,

  simple, safe, efficient and rational way.

  The problem which the invention proposes to solve is to allow the surgeon, with the same tibial base and the same femoral implant, to carry out either a fixed mounting of the tibial plateau, or a mobile mounting of the latter, and this with the same ancillary. Such a possibility makes it possible to respond to almost all the indications encountered in first intention

and in case of simple recovery.

  To solve such a problem, it has been designed and developed a tibial assembly for the knee joint of the type of those comprising, in a known manner, a tibial base receiving a tibial plateau able to cooperate with the condylar pads of '' a femoral implant. According to the invention,

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  the tibial base has arrangements for mounting at will either

  a fixed platform, or a mobile platform.

  To solve the problem of equipping the tibial base, either with a fixed plate or with a movable plate, the arrangements of the tibial base consist of: - a stabilization groove formed on the anterior side and capable of cooperate with a complementary boss formed in overflow from the underside of the fixed plate; 0 - by a hole formed on the posterior side for the engagement of a screw in the case of the fixed plate and, possibly, of a stability pin in the

mobile tray case.

  Advantageously, the tibial base has a clipping rim cooperating with arrangements complementary to the fixed plate and capable of

  guiding the moving plate.

  To resolve the problem posed of ensuring the connection of the fixed plate with respect to the tibial base, the fixed plate has, in its thickness, a housing for positioning the screw head capable of being screwed into

  a stability keel added from the tibial base.

  According to another characteristic, the hole of the tibial base is formed from a guide boss cooperating with a complementary shape

  of the fixed platform or the mobile platform.

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  Advantageously, the hole and the groove are positioned along the axis

median of the tibial base.

  Advantageously, in the case of a movable plate, a screw can be engaged directly in the hole of the tibial base, for fixing a

stability keel.

  Note that the hole can be temporarily closed with a plug that will suffice to be removed when installing the fixed plate or

mobile platform.

  The invention is set out below in more detail with the aid of the figures of the appended drawings in which: - Figure 1 is a top view of the tibial base according to the invention; - Figure 2 is a sectional view taken along line 2-2 of Figure 1; - Figure 3 is a cross-sectional view taken along line 3-3 of Figure 2; - Figure 4 is a front view of the fixed tibial plateau; - Figure 5 is a cross-sectional view taken along line 5-5 of Figure 4; FIG. 6 shows the tibial base equipped with the fixed tibial plateau; there is shown in broken lines an example of a femoral implant cooperating with the tibial plateau; - Figure 7 is a cross-sectional view taken along line 7-7 of Figure 6;

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  - Figure 8 is a front view of the movable tibial plateau; - Figure 9 is a cross-sectional view taken along line 9-9 of Figure 8; - Figure 10 shows the tibial base equipped with the movable tibial plateau; the femoral element has been shown in broken lines; - Figure 11 is a cross-sectional view taken along the

line 11-11 of figure 10.

  In a perfectly known manner, a knee prosthesis 0 comprises a tibial implant (T) and a femoral implant (F). The tibial implant (T) has a tibial base (1), generally metallic, intended to receive a polyethylene tray or insert. The plate is profiled transversely and longitudinally to receive, with capacity of

  flexion and slip, the condylar pads of the femoral element (F).

  According to the invention, the same tibial base (1) has arrangements for mounting at will, either of a fixed plate (2), or of a movable plate (3). Whatever the plate used, that is to say either the fixed plate (2), or the mobile plate (3), the femoral implant (F) remains identical. In other words, according to the invention, the same femoral implant is used, both with a fixed tibial plateau (2) and a mobile tibial plateau (3). The femoral implant (F) can have different embodiments. According to the invention, the tibial base (1) has a groove of

  stabilization (la) formed along its median axis near the anterior edge.

  This groove (la) is formed in the thickness of the tibial base from

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  its top face receiving the fixed (2) or mobile (3) plate. This groove (la) is formed symmetrically with the median axis of the tibial base (1) and over a limited length. This groove (la) is intended to receive a boss (2a) of complementary shape formed in overflow from the underside of the movable plate (2), on the side of its front edge. This groove (la) stabilizes the fixed plate (2) which is made integral with the base (1), without any possibility of displacement, by means of a screw (4) engaged in the thickness of the mobile plate ( 2) and in a hole (lb) formed in the thickness of the tibial base (1). The hole (lb) is formed on the posterior side of the tibial base (1), along its median axis of symmetry. As shown in Figure 5, the tiblal plate (2) has, in its thickness, a housing (2b) for positioning the screw head (4a). The screw (4) is engaged in the hole (lb) and screwed into a stability keel (5)

  reported at the level of the underside and support of the tibial base (1).

  For example, the screw (4) is screwed into an internal thread (5a) formed in

  the bottom of the stability keel (5) (Figures 6 and 7).

  Note that the tibial base (1) may have a clip edge

  (lc) cooperating with complementary arrangements (2c) of the fixed plate.

  This twist (2c) also makes it possible to guide the movable plate (3).

  As shown in figure 6, the plate (2) is therefore perfectly maintained in the tibial base (1) by means of the screw (4), the boss (2a) engaged

  in the groove (la) and the clip edge (lc).

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  The movable plate (3) is simply placed on the flat top face of the tiblale base (1) being therefore free from any rotary movement. Note that the hole (lb) can receive, in this case, a stability pin (not shown) able to cooperate with a groove or a guide notch formed in particular at the posterior level of the plate (2). Note, as shown in the figures of the drawings, that the hole (lb) is formed from a boss (ld) cooperating with a complementary lo form of guide (2d) of the fixed implant (2) or (3d ) from the set

mobile (3).

  Similarly, in the case of a movable plate (3), a screw can be engaged directly in the hole (ld) for fixing a stability keel. Finally, the hole (ld) can be temporarily closed by a plug which it suffices to remove when installing the fixed plate (2) or

  of the movable plate (3), depending on the pathological case to be treated.

  The advantages are apparent from the description, in particular one

  underlines and recalls the possibility, for the surgeon, of using the same tibial base and the same femoral element, by equipping said base, namely

  of a fixed plate, or of a mobile plate, and that with the same ancillary.

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Claims (1)

CLAIMS -1- Tibial assembly for the knee joint comprising a tibial base (1) receiving a tibial plate capable of cooperating with the condylar pads of a femoral implant, characterized in that the tibial base (1) has arrangements for mounting at will either of a fixed plate (2), or a movable plate (3). -2- An assembly according to claim 1, characterized in that the arrangements of the tibial base (l) are constituted: - by a stabilization groove (la) formed on the anterior side and capable of cooperating with a complementary boss (2a) formed in the overhang of the underside of the fixed plate (2); - by a hole (lb) formed on the rear side for the engagement of a screw (4) in the case of the fixed plate (2) and, optionally, of a stability pin in the case of the movable plate (3) . -3- The assembly of claim 2, characterized in that the tibial base (1) has a clip twist (lc) cooperating with arrangements complementary to the fixed plate (2) and capable of guiding the movable plate (3 ). -4- The assembly of claim 2, characterized in that the fixed plate (2) has, in its thickness, a housing for the positioning of the screw head (4) adapted to be screwed into an added stability keel (5 ) of the tibial base (l). 9 2838330   -5- The assembly of claim 2, characterized in that the hole (lb) of the tibial base (1) is formed from a cooperating guide boss   with a complementary shape of the fixed plate or the mobile plate.   -6- The assembly of claim 2, characterized in that the hole (lb) and   the groove (la) are positioned along the median axis of the tibial base (1).   -7- The assembly of claim 2, characterized in that, in the case 0 of a movable plate (3), a screw can be engaged directly in the hole