FR3095587A1 - Cup of an acetabular prosthetic system with variable thickness - Google Patents

Abstract

Cup of an acetabular prosthetic system of variable thickness Cup of an acetabular prosthetic system of substantially hemispherical shape having a lateral wall (1) extending between a free edge (2) and a vertex or pole (3) defining within it a cavity suitable for receiving an insert of a wear material having formed an auxiliary cavity for receiving a head of a neck of a femoral part in a hip prosthesis, the outer surface (7, 8, 9) of the side wall of the cup being coated with a layer (10) of porous material promoting osteosynthesis, and, following a longitudinal section, the radial thickness of the layer of porous material being variable along the surface between the edge free and the pole, characterized in that, following a longitudinal section, the radial thickness of the cup, excluding the coating layer of porous material, is variable between the free edge and the pole. Figure for the abstract: Fig. 1

Description

Cup of an acetabular prosthetic system with variable thickness

The present invention relates to a cup of an acetabular prosthetic system intended to be received at the bottom of the natural acetabular cavity of a patient, as well as to an acetabular prosthetic system of this type.

Conventionally, these acetabular prosthetic systems consist of a cup, often metallic, of substantially hemispherical shape, inside which is received an insert made of wear material, often polyethylene, in which is formed a cavity intended to receive a head from a neck of a femoral part of the total hip prosthesis to allow the pivot of the femoral part relative to the acetabular part.

It is known in the prior art, in particular from FR-B1-2997839 in the name of the applicant, to cover the cup with a coating made of a porous osteosynthesis material intended to receive within it bone material which develops over time to thus promote stable and durable fixation of the acetabular prosthetic system in the acetabulum. In addition, provision is made therein to deposit this coating in the form of a thickness gradient, the thickness of the coating decreasing from the free edge of the cup towards the top.

It turns out that this coating thickness gradient is difficult to achieve precisely. The present invention aims to overcome the drawbacks of the prior art by proposing a cup of an acetabular prosthetic system intended to be inserted at the bottom of the natural acetabular cavity of a patient which is as stable as those of the prior art, in particular which, although providing a thickness gradient, is simpler to manufacture.

According to the invention, a cup of an acetabular prosthetic system of substantially hemispherical shape having a side wall extending between a free edge and a vertex or pole defining within it a cavity which can receive an insert made of a wear material in which is formed an auxiliary cavity intended to receive a head of a neck of a femoral part in a hip prosthesis, the outer surface of the side wall of the cup being coated with a layer of porous material promoting osteosynthesis, and, along a longitudinal section, the radial thickness of the layer of porous material being variable along the surface between the free edge and the pole, in particular by decreasing at least over a first angular sector or interval of longitudes in the direction of the pole of the cup, in particular from the free edge, is characterized in that, according to a longitudinal section, the radial thickness of the cup, excluding the coating layer of porous material, is variable between the free edge and the top, in particular decreasing from the free edge towards the top, in particular decreasing from the free edge.

High precision is thus obtained in the development of the gradient of the total thickness of the cup, which makes it possible to obtain excellent control of the impaction for the surgeon, by making it possible to ensure a "press-fit" effect. " or "tight fit or force" perfectly adequate, implying great stability of the cup once inserted.

Preferably, the radial thickness of the layer of porous material is constant over a first range of coating longitudes, for example between about 0° and about 25°, then decreases, in particular linearly towards the pole, in particular down to the pole.

Preferably, the radial thickness of the cup, excluding the coating layer, is substantially constant over a first interval of cup longitudes, for example from 0° to 25°, then decreases over a transient interval of cup longitudes, by example from 25° to 40°, then is substantially constant over a second interval of cup longitudes, for example from 40° to 90°.

In particular, the first interval of cup longitudes and the first interval of coating longitudes are identical.

According to a preferred embodiment of the invention, in longitudinal section, that is to say in a plane passing through the axis extending between the pole and the center of the cup, that is to say in particular the center of the circle delimiting the free edge, the outer surface of the side wall of the cup comprises a first section in the form of an arc of circle extending over a first sector of angle, in particular between 0° and 25°, and a second circular arc section extending over a second corner sector, in particular up to the apex, in particular between 40° and 90°, each section having a respective radius R1 and R2, the first radius R1 being greater than the second radius R2 .

Preferably, the coating is rough, in particular has a roughness R _t > 100 μm, more preferably ≥ 150 μm.

According to a preferred embodiment of the invention, the total radial thickness of the cup, that is to say including the coating layer therein, is maximum at the level of the free edge of the cup and is minimum at the top. of the cup and decreases in a substantially linear manner from the edge to the top.

According to a favorable embodiment of the invention, the radial thickness of the coating is maximum at the level of the free edge of the cup and minimum at the top of the cup, in particular by decreasing in a substantially linear manner from the edge towards the top.

According to an advantageous embodiment, the thickness of the coating is constant over a first angular segment, in particular between 0° and 25°, then decreases over a second segment contiguous to the first segment, in particular linearly, for example between 25° and 90 °.

Preferably, there is provided along the outer surface of the wall of the cup a transition zone between the first section in an arc of a circle and the second section in an arc of a circle, in particular extending between 25° and 40°.

The present invention also relates to an acetabular prosthetic system consisting of a cup according to the invention and an insert made of wear material received in the cup, in which is made a cavity intended to receive the head of a neck of a femoral stem.

The present invention also relates to a total hip prosthesis comprising a femoral stem and an acetabular prosthetic system according to the invention.

By way of example, a preferred embodiment of the invention will now be described with reference to the drawings, in which:

Figure 1 is an overall view of a cup according to one embodiment of the invention; And

Figure 2 is a longitudinal sectional view of a cup according to the invention substantially identical to that of Figure 1.

In Figure 1, there is shown a cup according to the invention. This cup comprises a substantially hemispherical wall 1 extending between a free edge 2 and a vertex or pole 3. The cup also comprises means allowing its gripping for its insertion into the acetabular cavity which can take several forms, in particular, as shown in Figure 1, a tip 5 projecting from the free edge 2 of the hemispherical wall 1 and defining a peripheral groove 6 allowing the cup to be gripped and placed at the bottom of the acetabular cavity using a suitable ancillary, as described for example in French patent application 2 905 541. However, the present invention is not limited to these gripping means by the edge and instead, one could find another fixing means, in particular by passing through a hole formed at the top of the cup, as is also known in the prior art. In addition, the wall 1 may, as an option, comprise one or more windows such as the window 4 to allow the passage of bone fixation screws inside the cup.

Wall 1 is substantially hemispherical extending over an interval of longitudes from 0° (equatorial plane and plane of the free edge) to 90° (pole). In the case where a gripping tip is provided, the hemispherical wall 1 extends over the interval of longitudes between 0° and 90°, excluding the tip 5.

The hemispherical wall 1 has an outer surface which is covered with a coating 10. In FIG. left of the figure, the coating actually extending over the entire outer surface of the wall 1 or substantially the entire surface, with the exception of the hole or holes 4 and, in the case where it is provided for the opening 3 gripping at the pole.

In Figure 2, there is shown a sectional view of a cup substantially identical to that of Figure 1, in which the coating is not shown.

In longitudinal section, as shown in Figure 2, the wall 1 has an outer surface which is defined by a first section 7 in an arc of a circle, a transition section 8 and a second section 9 in an arc of a circle.

The first section in the form of an arc of a circle has a first radius R1 and extends over an angular sector or interval of longitudes comprised between about 0° and about 25°.

The transition section 8 extends over an angular sector or interval of longitudes comprised between about 25° and about 40°.

The second arcuate section 9 has a second radius R2 which is less than the first radius R1 and extends over an angular sector or interval of longitudes comprised between about 40° and about 90°.

The first radius R1 is for example equal to 26.6 mm and can be comprised for example between 23 mm and 33 mm, and the difference between the first radius and the second radius is equal to 0.4 mm, and can be comprised by example between 1.5 mm and 10 mm.

The two circular arcs of radii R1 and R2 respectively have the same center, in particular the center 11 of the equatorial circle.

The radii refer to the outer surface of wall 1.

The thickness of the wall 1 can be for example 3 mm and for example between 1.5 mm and 10 mm at the level of the second section (R2) and can be for example 3 mm and for example between 1.5 mm and 10 mm at the level of the first section (R1).

The coating 10 has a thickness which is substantially constant in the zone of the first section, that is to say from 0° to 25°, then from 25° to the pole, decreases, in particular in a linear manner.

No screws or similar means of fixation are provided for fixing the cup in the acetabular cavity, the presence of the thickness gradient ensuring sufficient fixation. However, if desired, provision may be made in addition to such fastening means, in particular by providing, in such a case, the corresponding windows 4.

Conventionally, the cup is made of metal, for example titanium or titanium alloy. It can also be made of stainless steel, cobalt, chromium, or the like, while the coating material can be, for example, titanium or tantalum.

Claims (9)

Cup of an acetabular prosthetic system of substantially hemispherical shape having a lateral wall (1) extending between a free edge (2) and a vertex or pole (3) defining within it a cavity which can receive an insert made of a material of wear in which an auxiliary cavity is formed intended to receive a head of a neck of a femoral part in a hip prosthesis, the outer surface (7, 8, 9) of the side wall of the cup being coated with a layer (10) of porous material promoting osteosynthesis, and, in a longitudinal section, the radial thickness of the layer of porous material being variable along the surface between the free edge and the pole, characterized in that, along a longitudinal section, the radial thickness of the cup, excluding the coating layer of porous material, is variable between the free edge and the pole. Cup according to Claim 1, characterized in that the radial thickness of the layer of porous material is constant over a first range of coating longitudes, for example between approximately 0° and approximately 25°, then decreases, in particular linearly towards the pole, especially up to the pole. Cup according to Claim 1 or 2, characterized in that the radial thickness of the cup, excluding the coating layer, is substantially constant over a first interval of cup longitudes, for example from 0° to 25°, then decreases over a transient range of cup longitudes, for example from 25° to 40°, then is substantially constant over a second range of cup longitudes, for example from 40° to 90°. Cup according to claim 2 and 3, characterized in that the first range of cup lengths and the first range of coating lengths are identical. Cup according to Claims 2 and 3, characterized in that in longitudinal section, that is to say in a plane passing through the axis extending between the pole and the center of the cup, that is to say i.e. in particular the center of the circle delimiting the free edge, the outer surface of the side wall of the cup comprises a first segment in the form of an arc of a circle extending over the first interval of longitudes, in particular between 0° and 25°, and a second section in an arc of a circle extending over the second interval of longitudes, in particular up to the summit, in particular between 40° and 90°, each section having a respective radius R1 and R2, the first radius R1 being greater than the second radius R2 . Cup according to one of Claims 1 to 5, characterized in that the total radial thickness of the cup, that is to say including the coating layer therein, is greatest at the level of the free edge of the cup and is minimal at the top of the cup and decreases in a substantially linear manner from the edge to the top. Cup according to one of Claims 1 to 6, characterized in that the radial thickness of the coating is maximum at the level of the free edge of the cup and minimum at the top of the cup, in particular by decreasing in a substantially linear manner from the edge towards the top. . Acetabular prosthetic system consisting of a cup according to one of the preceding claims and an insert made of wear material received in the cup, in which a cavity is formed intended to receive the head of a neck of a femoral stem . Total hip prosthesis comprising a femoral stem and an acetabular prosthetic system according to claim 8.