DE29609811U1 - Hip endoprosthesis system with special instruments for revision operations - Google Patents

Description

Abitz & Partners : : ·. ·: ::··. ······":

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European Patent Attorneys Dr. Dipi.-ciwm.

Patent Attorneys _&Mgr; . Gritschneder

Dipl.-Phys.

A. Frhr. von Wittgenstein

Dr. Dipl.-Chem.

J. Morf

Abitz & Partner, PO Box 86 01 09, D - 81628 Munich ^Dr - Dipi-chem.

Postal Address / Postal Address PO Box 86 01 09 D - 81628 Munich

3 June 1996 3 0215/Revision operations

KERAMED Medical Technology GmbH

At the Trillers Bushes 2

07646 Mörsdorf/Thuringia Federal Republic of Germany

Hip endoprosthesis system with special instruments for

Revision operations

The invention relates to the femoral part of a hip endoprosthesis, wherein the femoral part has a bore for a locking element in the distal area, including an instrument for aligning the bore to be made in the femur. 5

Hip endoprosthesis has been a standard operation for more than two decades, used to treat diseases or damage to the hip joint. In line with the state of medical and technical development, hip endoprostheses have a

&iacgr;&ogr; limited lifespan. Some prostheses, however, fail after 10 years or less. The main reason for this is a loosening of the connection between the natural living bone and the implant. This causes disruptions in the functionality of the artificial joint and requires revision of the artificial joint. Due to the large number of primary hip endoprosthesis operations, the number of these secondary operations, the revision operations, is also constantly increasing. Depending on the type of loosening of the prosthesis, the revision operation is more or less difficult. In some of these cases, the bone is in

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significantly damaged, so that anchoring the implant for revision presents particular difficulties.

Especially in cases of peri- and subprosthetic fractures as well as large bone defects resulting from tumors and osteo-atrophies, it is advisable to lock the prosthesis in the distal area with screws. For such indications an intramedullary nail is known, which in the distal area

Î is locked with screws. This nail is not suitable for revision surgery with a prosthetic hip joint, as the intramedullary space of the femur is occupied by the prosthesis. This locking places high demands on the surgeon in terms of surgical technique and it is essential to use an image converter for this locking. The image converter works with X-rays, so that the patient and the operating room staff are exposed to radiation.

The invention is based on the object of simplifying the locking of the shaft of a hip endoprosthesis in the femur.

According to the invention, this object is achieved by a drilling jig for the hole to be made in the femur for the locking element, wherein the drilling jig can be detachably connected to the femoral part and has a drilling sleeve which is aligned with the hole in the distal region of the femoral part when the drilling jig is connected to the femoral part.

Because the guide sleeve is aligned with the hole in the femoral part, the necessary hole can be drilled in the femur without displacement. The drill bit is prevented from slipping or sliding sideways.

Preferably, a dovetail guide is provided on the shaft of the femoral part for the detachable connection to the drilling jig

provided, whereby the dovetail guide runs conveniently at right angles to the axis of the prosthesis shaft.

Preferably, a threaded hole for a screw connection with the drilling jig is also provided in the shaft of the femoral part.

In general, two holes are provided in the distal area of the femoral component and the drill guide has two corresponding guide sleeves.

The shaft of the femoral component has a surface structure, either completely or partially, that promotes bony integration.

The drilling jig has a modular design and can therefore be adjusted to different shaft lengths.

An embodiment of the invention is described below with reference to the drawing.

Fig. 1 the femoral part and the associated drilling jig from the side and

Fig. 2 shows an oblique top view of the femoral part with the dovetail guide.

According to Fig. 1, the femoral part of the hip endoprosthesis system has a prosthesis shaft 10, which has two holes 12, 14 at the lower, distal end, and a conical receiving pin 16 for the joint ball, which protrudes obliquely at the front of the upper end of the prosthesis shaft 10.

A target device in the form of a drilling jig 20 is detachably attached to the upper end of the prosthesis shaft 10. The drilling jig 20 essentially consists of a cross rail 22 running transversely to the axis of the prosthesis shaft 10 and a cross rail 22 extending from the cross rail 22 at right angles to it and parallel to the axis of the prosthesis.

thesis shaft 10 extending arm 24. At the lower, free end of the arm 24, two guide holes 26 are provided, the axes of which are aligned with the holes 12, 14 at the distal end of the prosthesis shaft 10.

For secure but detachable fastening of the cross rail 22 to the prosthetic shaft 10, the latter is provided dorsally with a dovetail guide 30, onto which a foot 32 is pushed, which is provided with corresponding dovetail guide elements. A threaded hole 34 is also provided within the dovetail guide 30, into which a threaded bolt 36, which is rotatably mounted within the foot 32, can be screwed in in order to clamp the foot 32 against the upper end of the prosthetic shaft 10. The threaded bolt 36 is provided with a handle 38 for screwing in. The cross rail 22 is attached to the foot 32. The arm 24 can be moved along the rail 22 in suitable guide means and can be fixed by means of an adjusting screw 40. The length of the arm 24 is matched to the length of the prosthetic shaft 10.

Guide sleeves 42 are inserted into the guide holes 26 at the lower end of the arm 24, which prevent the drill from sliding sideways when drilling the holes in the femur.

Claims (5)

PROTECTION CLAIMS 1. Femoral component of a hip endoprosthesis, wherein the femoral component (10, 16) has a bore (12, 14) for a locking element in the distal region and an instrument is provided for aligning the bores to be made in the femur so that they are aligned with the bores (12, 14) present in the distal region of the femoral component (10, 16), characterized in that the alignment instrument is a drilling jig (20) for the bore to be made in the femur for the locking element, wherein the drilling jig (20) can be detachably connected to the femoral component (10, 16). 2. Femoral component according to claim 1, characterized in that the drilling jig (20) has a cross rail (22) which can be tensioned by a foot (32) at one end against the proximal end of the prosthetic shaft (10) of the femoral component and which carries an arm (24) which runs parallel to the prosthetic shaft (10) and at the free end of which a guide bore (26) is provided, the axis of which is aligned with the bore (12, 14) in the distal region of the femoral component. 3. Femoral component according to claim 1 or 2, characterized in that the drilling jig (20) can be connected to the prosthesis shaft (10) by means of a dovetail connection (3 0). 4. Femoral component according to one of the preceding claims, characterized in that the drilling jig (20) can be clamped against the prosthesis shaft by a threaded bolt (36) which can be screwed into a threaded bore (34). 5. Femoral part according to claim 2, characterized in that the dovetail guide (30) runs at right angles to the axis of the prosthesis shaft.