DE20021917U1 - Endoprosthesis adapter - Google Patents

Description

Merete Management GmbH

Fasanenstrasse 51

10719 Berlin Berlin20.12.00

ana-agGbm700

Adapter for endoprostheses

The innovation concerns an adapter for endoprostheses, in particular a plug adapter not only for hip joint revisions, but also for the exchange of a ceramic plug head from the metal cone of an implanted shaft and subsequent reconstruction and a continuous correction setting of the CCD angle and the neck length compensation, whereby an adapter with an eccentric inner cone has a recess at its point with the greatest wall thickness opposite the eccentric inner cone to increase the total deflection angle (ROM) relative to the socket.

The use of adapters for endoprostheses, as a link between the shaft of an implanted hip endoprosthesis and the plug-in ball, is widely known.

In order to allow the greatest possible deflection of the hip relative to the hip socket, known as ROM - Range of Motion -, adapters are already known that are constricted or narrower at the points of contact with the stationary socket.

Another solution to increase the range of motion (ROM) is to narrow or reduce the diameter directly below the shaft of hip endoprostheses.

For example, the German utility model G 299 08 391 discloses a joint prosthesis system in which an elongated adapter with an inner and outer cone can be placed on a conical shaft of an implanted hip endoprosthesis, whereby a joint ball with a corresponding inner cone can be placed on the outer cone. The adapter has a constriction in the area outside the plug-in ball that reduces the outer diameter in order to achieve a greater deflection (ROM) of the hip. However, this is a straight adapter whose inner cone has no eccentricity to the outer cone.

Even for adapters with eccentricity between the inner cone and the outer cone, especially if the center axes of the inner cone and the outer cone are not parallel, the angle of deflection (ROM) is limited. This angle is generally between 126° and 134°.

The innovation therefore has the task of reducing the deflection angle of adapters with eccentricity between the inner cone and the outer cone.

without compromising the stability and strength of an adapter's wall thickness.

To solve this problem, it is proposed to provide the adapter with a recess, not over the entire circumference, at the point opposite the eccentric inner cone with the greatest wall thickness and outside the overlap area of the plug-in ball. This recess runs outwards again to the outer diameter of the adapter after almost three quarters of the circumference.

Further advantages are evident from the following description and are explained in more detail using drawings. It shows:

Fig. 1 A ball joint with the angle of maximum deflection, Fig. 2 an adapter with a recess on the circumference.

Fig. 1, for example, shows only the basic components of a hip endoprosthesis, with socket 1, joint ball 2 and a shaft 3 of an endoprosthesis, although this can also be part of an adapter. The greatest possible deflection to the left is shown, with shaft 3 and socket 1 touching at point 4. The greatest possible deflection to the right is shown by line 5, resulting in a largest deflection angle ROM. The shaft 3 has already been greatly reduced in diameter compared to ball 2.

If it is necessary to use an adapter with eccentricity between the inner cone and the outer cone, for free adjustment of the CCD angle and simultaneous neck length compensation, an adapter 10 as shown in Fig. 2 is used. This adapter 10 has an outer cone 11 and an inner cone 12, with its central axis 13 inclined to the central axis 14 of the adapter. If the inner cone is later seated on the shaft of an implanted endoprosthesis, the surgeon can freely adjust the joint ball 20 to all positions between valgus-varus and retrotorsion and antetorsion.

The adapter 10 now has a recess 15 on its outer circumference, preferably at the point of greatest wall thickness to the inner cone 12, which is designed as a type of groove as shown. This recess 15 tapers back to the remaining outer diameter after almost three quarters of the circumference. This recess 15 can also be designed in such a way that it runs evenly and parallel to almost half the circumference and only then rounds back to the outer diameter. With an adapter 10 designed in this way, the deflection angle (ROM) can be increased by several degrees.

Claims (6)

1. Adapter for connecting a joint ball to a pin and circumferential constriction in the area of the outer diameter, characterized in that the adapter ( 10 ) has an eccentricity between the outer cone (119) and the inner cone ( 12 ) and has a recess ( 15 ) which does not extend over the entire circumference. 2. Adapter according to claim 1, characterized in that the recess ( 15 ) is arranged outside the area covered by the joint ball ( 20 ). 3. Adapter according to claim 1, characterized in that the recess ( 15 ) is located at the point of greatest wall thickness to the inner cone ( 12 ). 4. Adapter according to claim 1, characterized in that the recess ( 15 ) is located at the point of greatest wall thickness to the inner cone ( 12 ) and from there takes up three quarters of the outer circumference of the adapter ( 10 ). 5. Adapter according to claim 1, characterized in that the recess ( 15 ) tapers centrally to three-quarters of the outer circumference to the outer diameter. 6. Adapter according to claim 1, characterized in that the recess ( 15 ) runs parallel at the same depth up to three quarters of the outer circumference of the adapter ( 10 ).