DE9402828U1 - Metal-supported cup prosthesis as a joint surface replacement for the hip joint - Google Patents

Description

15 FEBRUARY '94 14:52 FEDERAL CHILDREN'S ASSOCIATION KL.PUETTLINGEN "'^:; , · p.2/7 ^;> . ^

Prof. Dr. med. K. Diehl Püttlingen, 15.02.1904

Prof./Hen.

Subject: Registration of a meiaHgeatUtztan shell prosthesis for the hip joint for Utility model protection

The application covers a joint surface replacement for artificial joint replacement in the case of destructive diseases of the hip joint. The artificial joint consists of 3 parts.

1. A spherical cap made of metal or ceramic (Figure 3), the opening of which extends just beyond the largest diameter.

The cap is used as a joint replacement for the femoral head. After the bony femoral head has been milled spherically to match the inner shape of the cap, it is placed over the femoral head and secured with bone cement.

2. From a two-part artificial pan (Figures 1 and 2).

The outer part of the artificial socket consists of a metal shell. The basic shape of this shell is initially cylindrical, then conical and spherical in the dome area. In the cylindrical section of the metal shell, a self-tapping thread runs around the entire circumference. The threads are interrupted. Rising edges mean that the thread in the bone has a self-tapping effect.

The articular surface of the artificial joint is provided by a plastic insert. This is inserted into the metal shell. The outer shape of the plastic insert corresponds to the inner shape of the metal shell. The conical part ensures secure and non-displaceable clamping and loading. The dome of the plastic insert is 2/10 mm away from the inside of the metal shell. This ensures clamping in the conical area of the metal shell.

The plastic insert is designed in the edge area so that when the hip joint is realigned, the artificial femoral head does not come into contact with the metal shell.

15 FEBRUARY '94 14:52 BUNDESKNAPPSCHplFT KL.PUETTLINGEN «-«««^pwi^ *"'P.'3/7

General justification for registration:

The replacement of joint surfaces with shell prostheses is not new in itself. The shell prostheses replaced so far consist of:

a) a cap made of metal or ceramic, which is applied to the appropriately prepared femoral head either by clamping it without cement or with bone cement.

b) made of a plastic shell, the inside of which corresponds to the shell of the femoral head. The plastic shell is attached to the shell prostheses that are still commonly used today with a screw into the natural socket of the pelvis.

However, the long-term results of this type of joint replacement are not good enough in the majority of cases. The high static and dynamic pressure that occurs when walking and standing and presses the femoral head into the artificial socket leads to walking movements, increases plastic wear and changes the plastic shell in the sense of cold deformation.

The loosening rate of this shell prosthesis is still so high that this type of joint replacement has been abandoned.

In the shell joint being applied for, the harmful cold deformation of the plastic shells is effectively prevented by supporting them with a metal casing.

The metal shell is provided with a self-tapping external thread. When implanting it, the natural bony hip socket must be milled out to match its shape. The threads cut firmly into the bony wall of the socket. This ensures an immediate and firm, movement-stable fit. This avoids the need for additional fastening of the metal shell with cement. It also avoids destruction of the bony socket bearing due to abrasion of the bone cement. The secure and shift-proof attachment between the metal shell and the inserted plastic insert is created by the corresponding conical surfaces on the inside of the metal shell and the outside of the plastic insert.

The plastic insert has a thicker wall in the area of the main load. In the other areas subject to less stress, the wall of the metal shell is considerably thinner. This makes it possible to keep the overall external dimensions of the artificial joint or the artificial socket so small that the joint can be implanted without excessive milling of the natural bony socket.

Depending on the different sizes of the natural hip joints, several sizes of the joint being registered will be produced.

,' 15, FEBR.'',' 94 14= 53: BUfSULbKNHPHbCHHt- I KL. PUL I IL-1

Fig. &Agr;.:

�Ogr;&Igr;&Egr; SHELL ENDOPROSTHESIS

in aO side view

In t>> View front butt

. Head scarf«

THE SLEEVE ENDOPROSTHESIS in cross section

1. fvt et «.II se haie

Jc*. Ki4ot»t5stoffoirii»««.-t3=

3. Femoral head echale

The movement of the joint occurs between 2 and 3

^; · ^;: 15'FEBR. '94' ^: 14:52 BUNDESKNt=IPPSCHAFT KL. PUETTLINGEN '"''.'■'■V',. P. 4/7 - ^&Lgr; 'V'■'

Fig. O:

SIDE VIEW OF TEH-E

1. the S- of the synthetic fabric seam 3. of the hip cap

-15 FEBRUARY ''94-14!53"'SDRDESKFiSpPSCHplFT KL.PUETTLINGEN

1 M«tal ^|schal# &bgr;. Kun.««-«· ¹ " 3.

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Claims (1)

Protection claims Metal-supported shell prosthesis as articular surface replacement for the hip joint, characterized by - a three-part structure of the artificial joint, namely a spherical cap made of metal or ceramic as a joint replacement for the femoral head, which is placed over the femoral head after spherical milling of the bony femoral head and secured with bone cement, and - a two-part artificial pan, consisting of an outer metal shell with a plastic insert inserted into it, - The shape of the metal shell is initially cylindrical, then conical and spherical in the dome area, self-tapping thread with interrupted threads and rising edges in the cylindrical section of the metal shell around its entire circumference, - Plastic insert represents the articular surface of the artificial joint, outer shape of the plastic insert corresponding to the inner shape of the metal shell, secure and non-slip clamping and loading due to the conical part, whereby the dome of the plastic insert has a distance of 2/10 mm to the inside of the metal shell.