DE10237016A1 - Modular wrist implant, comprising convex elliptical part joined with cylindrical shaft to concave elliptical socket - Google Patents

Abstract

The basic implant is assembled of a convex part designed in the shape of half an ellipsoid and a matching concave socket transversally joined to the bones (4, 5) of the lower arm in order to facilitate a natural movement of the hand. The socket can be additionally provided with a concave area for the accommodation of the curved bone part. All parts are attached by inserting a cylindrical shaft (1, 2, 8) into the appropriate bone area (4, 5). More modules can be added if required.

Description

The invention relates to a modular unguided Wrist prosthesis, which is the most extensive restoration of the Function of a wrist destroyed by various clinical pictures or an accident allows the besides by destruction conditioned permanent pain in destroyed Wrists eliminated.

The natural wrist can only be moved in two directions. The hand can be against the forearm be angled, which means a movement back and back of the hand and it can be angled sideways against the forearm. So the hand moves from top to bottom and back both sides while the Palm rotation over a There is movement between the ulna and the spoke. Should be the full function of the wrist are natural Movements meant.

So the wrist must be shaped like this be that natural movement possibilities hand if possible Completely to be restored, additional not natural movement possibilities but subdued become.

There are several in prosthetics Wrist prostheses known, mostly from known more or less biocompatible Metals are made.

The US 5,782,928 shows a prosthetic wrist that is placed between the scalp and the spoke. The distal part of the wrist prosthesis is implanted with two screws in the scalp to prevent torsion of the prosthesis in the scalp, and the proximal part of the wrist prosthesis is implanted with very long pins in the spoke. Since the joint of this wrist prosthesis lies as a ball joint in a socket that is flattened to the ulna, and the joint between the spoke and ulna has to be resected, this rotational movement of the hand against the forearm cannot be dampened.

If the cubit is due to illness must be resected, it remains without a connecting joint to the spoke free in the forearm, so that after a short time to the cause Significant pain in the forearm

In the EP 1 031 322 A wrist prosthesis is described which has a carpus element to be implanted in the metacarpal bone, a radial element to be fixed to the forearm bone and an intervening transverse axis joint, the proximal part of the transverse axis joint being connected to the radial element. The distal part of the wrist prosthesis has three shafts that are implanted in the metacarpus. This wrist prosthesis realizes a hand movement in the two natural directions.

In the US 5,766,258 a wrist prosthesis is described. This wrist prosthesis has a proximal joint for the biaxial movement of the hand and a distal pivot axis that is connected to the proximal joint and two shafts that are anchored in the metacarpus. This wrist prosthesis is supposed to realize the two natural directions of movement of the hand.

Another wrist prosthesis is in the DE 198 20 015 described. The proximal section of the wrist prosthesis is anchored in the ulna with the spoke and in a further development with a long screw. The distal section is connected to at least one, especially two metacarpal bones.

The key disadvantages of the latter wrist prostheses are extremely complicated Structure, their size and in the fact that they have an implantation of the stems up deep into the spoke or through the scalp into the metacarpals desire. There are often several in the proposed solutions distal stems provided that are implanted into the metacarpals and rigidly connect the carpal bones to the metacarpals. This means that predetermined breaking points are preprogrammed in this area. In practice it happens frequently to breaks in the area of these rigid articular bridges. On the other hand, the shafts or screws loosened over time, especially regularly in the metacarpals. As a result, such a wrist prosthesis needs to be explanted, whereby large bone deficits remain according to their size. Limit these bone deficits to a considerable extent the revision options and reduce additionally the audit results.

It is the task of the present Invention to propose a wrist prosthesis that is simple Has structure that is natural Movement of the hand largely restores one as possible has small size and only one if possible requires minimal bone resection. The wrist prosthesis supposed about it can also be easily implanted.

The object is solved by the features of the appended claims. The modular non-guided wrist prosthesis consists of two joint parts, a first distal joint head, which consists of a convex semi-elipsoid with shaft and is press-fitted into the scalp, a second proximal socket, which consists of a concave semi-elipsoid with a shaft, and which is implanted with a press fit in the spoke. The radii of the two joint parts are so on each other which are coordinated that a functional joint is present between the joint head and the socket. The two joint parts preferably consist of a zircon ceramic body.

The joint socket can in one embodiment have a concave depression on the side facing the ulna, in which the joint ball of the elbow head is stored, if this joint is also inoperable.

It can also be a third proximal Joint part made of zirconium ceramic can be provided, which consists of a cylindrical brains with a shaft arranged perpendicular to it and into the Elle is implanted, with the cylindrical head laterally in functional Replica of the natural Joint between spoke and ulna in the concave depression of the Joint socket is stored.

It can be in another embodiment there is also another fourth proximal joint part, which is implanted in the side of the spoke and the one is concave Deepening for the Elleköpfchen or the cylindrical head of the third proximal joint part. This fourth proximal Joint part can also be used independently are implanted in the spoke if e.g. only the joint head of the Elle damaged is.

In another embodiment the joint head can have a second shaft, that in the hook leg is implanted. Likewise, a second can on the socket Shank can be provided, the one shaft on the socket eccentrically is shifted in the direction opposite to the cubit and the second Shaft is arranged on the cell side and also implanted in the spoke becomes.

• 1. Ersatz des Handgelenkes zwischen Speiche und Handwurzel zur Wiederherstellung der Abwickelung gegen den Unterarm und der Bewegung handrücken- und hohlhand-wärts und Ersatz des Teilgelenkes zwischen Elle und Speiche zur Wiederherstellung der Drehbewegung um die Längsachse, wenn eine Zerstörung beider Gelenk-Bereiche durch Trauma, Arthrose, Rheuma u.a. vorliegt.
• 2. Handgelenkersatz zwischen Speiche und Handwurzel zur Wiederherstellung der Abwinkelung gegen den Unterarm und der Bewegung handrücken- und hohl-handwärts, wenn eine Zerstörung des Gelenkes durch Trauma, Arthrose, Rheuma u.a. vorliegt.
• 3. Handgelenkteilersatz zwischen Elle und Speiche zur Wiederherstellung der Drehbewegung der Hand um die Längsachse, wenn eine Zerstörung des Köpfchens und der Pfanne z.B. durch Arthrose, Trauma u. a vorliegt.
• 4. Handgelenkteilersatz zwischen Elle und Speiche zur Wiederherstellung der Drehbe-wegung der Hand um die Längsachse, wenn eine Zerstörung des Köpfchens z.B. durch Trauma u. a vorliegt.

The following basic combinations (modules) are possible when using the non-guided hip joint prosthesis

• 1.Replacement of the wrist between the spoke and wrist to restore the development against the forearm and the movement of the back of the hand and the palm of the hand, and replacement of the partial joint between the ulna and spoke to restore the rotary movement around the longitudinal axis if both joint areas are destroyed by trauma , Arthrosis, rheumatism etc. is present.
• 2. Wrist replacement between the spoke and the wrist to restore angulation to the forearm and the movement of the back of the hand and the hollow hand if the joint is destroyed by trauma, arthrosis, rheumatism, etc.
• 3. Wrist part replacement between the ulna and the spoke to restore the rotary movement of the hand around the longitudinal axis if the head and the pan are destroyed, for example by osteoarthritis, trauma and the like. a is present.
• 4. Replacement of the wrist part between the ulna and the spoke to restore the rotation of the hand around the longitudinal axis if the head is destroyed, for example by trauma and the like. a is present.

The implantation of the wrist prosthesis begins with the implantation of the distal part of the wrist prosthesis in the head leg, or in the head leg and the hook leg, if the Rod end two shafts has. Depending on the degree of destruction of the wrist, the spoke is then resected in the wrist area. Subsequently becomes the proximal joint part, the socket of the wrist prosthesis implanted in the spoke. Is the joint between the spoke and Elle still functional, this part of the wrist did not have to be resected, will leave it as it is. Then the distal and promimal Joint part, the joint head and the socket, to a joint merged.

Is also the joint between the spoke and destroyed Elle, or the wrist is deformed due to illness, the Elle to over the ulnar joint can also be resected. It becomes an implant consisting of a cylindrical head with a vertical one arranged sheep, implanted in the cubit and the cylindrical Brains on the side in a functional replica of the natural joint between the spoke and ulna in the concave recess of the second proximal joint part stored.

But it is also possible that e.g. due to osteoarthritis or after an accident only the head of the ulna, as well as the counter bearing in the spoke is destroyed, and so only the rotary movement hand significantly affected becomes. A restoration of the function of the natural Wrist can be achieved in this case by that here as the third joint part, the third joint part called the ulnar head is implanted in the ulna and a small socket as a counter bearing is implanted in the spoke if this side of the ulnar joint is also destroyed.

The inventive wrist prosthesis met significantly increased Measure the Requirements for optimal wrist restoration. The functions of the wrist are restored to a high degree. Movements of the back of the hand, the hand and sideways bending as well as the rotation of the palm around the longitudinal axis are possible again and the one with the destruction permanent pain associated with a wrist is eliminated.

The innovative modular non-guided wrist prosthesis is a modular system, which means that the prosthesis only so little bone for the implantation as absolutely necessary, and adapted only the affected joints or Joint parts replaced.

The surgical technique is simple and the expenditure on instruments is extremely low, which means Cost savings and short operating times. The prosthesis consists of zirconium ceramic with a sintering of bioverite at the contact points with the bone and it is a whole body. First, it follows that there is no friction at the contact points of different materials, and second, there are no abrasion particles that can lead to body reactions. The pairing is also abrasion-free and the Bioverit sintering guarantees very good bone integration into the prosthesis, ie no strain on the immune system, no giant cells and a long-term stable bond between the bone and the prosthesis

The invention is intended to: some embodiments explained become. The same reference numbers denote in the individual representations same or similar Parts.

1A and 1B shows a distal joint head according to the present invention with a shaft in a view from the side and from the shaft;

2A and 2 B shows a distal joint head according to the present invention with two shafts in a view from the side and from the shaft;

3A and 3B shows a proximal socket according to the present invention with a shaft in a view from the side and from the shaft;

4A and 4B shows a proximal socket according to the present invention with two shafts in a view from the side and from the shaft;

5A and FIG. 5B shows an acetabular cup with a shaft which is off-center in the direction opposite to the ulna, viewed from the side and from the shaft; 6A and 6B shows an acetabular cup, which has two shafts, in a view from the side and from the shaft;

7A and 7B shows a third proximal joint part which is attached to a second proximal joint part in a view from the side and from the shaft;

8th shows a first embodiment of a prosthetic wrist; and 9 shows a second embodiment of a prosthetic wrist.

In 1A and 1B is a distal rod end according to the present invention with a shaft 1 in a side view and a view from the shaft 1 shown here. The shaft 1 has an oval cross-section. The shaft inserted in a round hole 1 gets a good press fit. The curvature is in the side view 3 recognizable in the longitudinal axis of the semi-ellipsoid. This semi-elliptical shape of the curvature 3 guarantees that only movements around the two ellipse axes can be carried out. The non-guided wrist is implanted so that the long axis of the semi-ellipsoid is parallel to the line connecting Elle 7 and spoke 6 lies so that the hand can be angled against the forearm, i.e. a movement of the back of the hand and hollow-handward, and the short axis of the half-ellipsoid is naturally perpendicular to it, so that the hand is angled sideways against the forearm. The shaft 1 gets into the scalp 4 implanted.

2A and 2 B shows a distal rod end according to the present invention with two shafts 1 . 2 in a side view and a second view of the shafts 1 . 2 ago. In this embodiment, the second shaft 2 Different from the distal condyle shown in Figure 1A, the second shaft 2 Implanted in the hook leg. In this embodiment, additional protection against rotation is provided.

3A and 3B shows a proximal socket according to the present invention with a shaft 1 in a side view and a shaft view 1 ago. The joint socket is adapted in the semi-elliptical shape to the distal joint head, so that the distal and proximal joint part slide into one another. The implantation of the socket in the spoke 6 also takes place with the longitudinal axis of the semi-ellipsoid towards the ulna 7 and with the transverse axis of the semi-ellipsoid naturally perpendicular to it. As a result, the movement about the longitudinal axis of the half-ellipsoid is a movement of the back of the hand and a hollow hand, and the movement about the transverse axis of the half-ellipsoid is a lateral movement of the hand.

4A and 4B shows a proximal socket with two shafts according to the present invention 1 . 2 in a side view and a view of the shafts 1 . 2 ago. The implantation is carried out in the same orientation as in the socket 2 , The second shaft 2 is in the yard 7 implanted. It serves as an additional safeguard against twisting.

The 5A and 5B shows a proximal socket with a shaft 1 for implantation into the spoke 6 in a side view and a shaft view 1 ago. The shaft 1 is extravagant in the direction opposite the cubit 7 shifted when the proximal socket in the spoke 6 is implanted.

6A and 6B shows an embodiment with two shafts, 2, for implantation in the spoke 6 , the implantation is done so that the stem 1 the greatest distance to the yard 7 has.

7A and 7B shows a third proximal joint part which is attached to a second proximal joint part in a view from the side and a view from the shafts 2, 8. It is a second proximal socket in accordance with the invention, which is in the spoke 6 is implanted. The second proximal joint part has a lateral hemispherical depression 9 in which a corresponding joint ball 10 the third proxima len joint part is inserted. It represents the replacement of the joint between the spoke 6 and Elle 7 represents.

8th shows a first embodiment of a non-guided prosthetic wrist, which consists of two joint parts, a first distal joint head, which consists of a convex semi-elipsoid with two shafts 1 . 2 consists of a press fit in the scalp 4 and hook leg 5 are implanted, a second proximal socket that consists of a concave semi-elipsoid with a central shaft 1 consists of a press fit in the spoke 6 is implanted. The radii of the two joint parts on the longitudinal axis of the half-ellipsoid and on the transverse axis of the half-ellipsoid are matched to one another in such a way that a functional joint is formed between the joint head and the socket. The socket has on the Elle 7 facing side a concave recess 9 in which the joint ball 10 of the third proximal joint part is mounted, so that the two proximal joint parts form a functional joint between the spoke 6 and Elle 7 form..

9 shows a second embodiment of a prosthetic wrist. In this exemplary embodiment, the first joint part has a shaft 1 that in the scalp 4 is implanted and the second proximal joint part has two shafts 1 . 2 that in the spoke 6 are implanted. The concave depression 9 on the second joint part there is an additional implant 11 that on the side of the yard 7 in the spoke 6 is implanted. This embodiment is indicated when the joint part of the spoke 6 only needs to be resected to a small extent, but also the joint between the spoke and the ulna.

Only a few exemplary embodiments are shown and explained. But there are other combinations of the individual prosthetic joint parts possible, all of which are intended to fall within the scope of the patent. the goal is it is always as complete as possible with little effort of the wrist. That also means that so little Bone mass is resected as required for this purpose.

Claims (7)

Modular non-guided wrist prosthesis consisting of two joint parts, a first distal joint head, which consists of a convex semi-elipsoid with shaft ( 1 ) and is press-fitted into the scalp, a second proximal socket that consists of a concave semi-elipsoid with a shaft ( 1 ) and with a press fit in the spoke ( 6 ) is implanted, the radii of the two joint parts being matched to one another in such a way that a functional joint is present between the joint head and the socket, and that the two joint parts consist of a zirconium ceramic body. Modular non-guided wrist prosthesis according to claim 1, in which the socket on the ulna ( 7 ) facing a concave recess ( 9 ) in which the joint ball ( 10 ) of the head of the elbow. Modular non-guided wrist prosthesis according to claim 1 or 2, in which a third proximal joint part made of zirconium ceramic is provided, which consists of a cylindrical head with a shaft arranged perpendicular to it ( 11 ) exists and in the cubit ( 7 ) is implanted, the cylindrical head ( 12 ) laterally in a functional replica of the natural joint between the spoke ( 6 ) and Elle ( 7 ) in the concave depression ( 9 ) the socket is supported. Modular non-guided wrist prosthesis according to claim 3, in which a fourth proximal joint part is present, which lies on the ulcer side in the spoke ( 6 ) is implanted and that is a concave recess ( 9 ) for the Elle head or the cylindrical head ( 12 ) of the third proximal joint part. Modular non-guided wrist prosthesis according to one of Claims 1 to 4, in which the joint head has a second shaft ( 2 ) who has in the hook leg ( 5 ) is implanted. Modular non-guided wrist prosthesis according to one of Claims 1 to 5, in which the shaft ( 1 ) off-center on the joint socket towards the ulna ( 7 ) is shifted and into the spoke ( 6 ) is implanted. Modular non-guided wrist prosthesis according to one of claims 1 to 6, in which a second shaft ( 2 ) is provided, which is also in the spoke ( 6 ) is implanted.