DE19611249A1 - Joint prosthesis and removal tool - Google Patents

Abstract

The joint prosthesis (1) has a socket shaped mounting part (2) and a joint cup insert (3) made from a ceramic material. A removal tool (10) is provided for removing the insert from the socket and has grip pieces (16) which engage in the insert. The mounting socket has a cut out section (5) which opens onto the open side (4) of the prosthesis and the insert. - The grip pieces are introduced into the cut-out section and can rotate relative to the insert. The grips can engage behind the edge of the insert. The tool may have a shaft (12) on which an impulse weight (19) can slide to hit against a stop (18) to produce the necessary force for removal of the insert.

Description

The present invention relates to a joint prosthesis with a pan-shaped support part in which a kera mixer insert is fixed, and a associated extraction tool.

Joint prostheses are known, which have a metallic Trä gerteil and have an insert contained therein. The insert forms a wear-resistant sliding surface, against which the joint ball of the bone or another Ren prosthesis presses. The metallic support part, that carries an insert is anchored in the bone. At Wear of the insert must be replaced the. To minimize the burden on the patient, the insert is removed from the carrier part in situ, while it stays on the bone. According to the current i In accordance with the state of the art, the insert is destroyed. This operation is difficult to carry out and involves also dangers to the patient. This is how fragments arise  in the destruction of the insert and tissue injuries can by up to destroy the mission brought strength to be evoked.

DE-PS 44 29 026 C2 describes an instrument for Removal of plastic inserts their carrier part. The instrument instructs concentrically orderly cutting edges or tips that slide into the surface of the insert are pressed so that a positive connection between instrument and on sentence arises. So it becomes possible to use the to remove a train movement. The instrument is only suitable for use in which an instrument is used appropriate tips can penetrate.

The invention has for its object a Kombina tion from a joint prosthesis with ceramic insert and to create an extractor in which the Insert can be removed without deforming intervention can.

This object is achieved by the features of claim 1 solved.

In the invention, the connection between tools and insert not on the inside of the insert, son made on the outside. This will be there achieved by at least one in the carrier part Recess is attached to the opening side of the Joint prosthesis and is open for use. The out Take is designed so that a gripper in it can be introduced. The grippers are in the recess introduced until they reach the edge of the insert.  

Then they are ge in a swivel motion closed, so that a positive connection is provided. For gripping the gripper on the insert can have as many recesses on the support part be present as the extractor has gripper. It but it is also possible to have a single rotating Provide recess so that the tool in any rotational position in the prosthetic joint can be introduced.

In a further preferred embodiment of the invention the extraction tool has a shaft on which an im pulse weight is displaceable against a stop. There through, after using the gripper a force conclusive connection for use has been established is the necessary force to release the insert be generated. The pulse weight is first on the Shank in the direction of use in an initial position tion brought. From there the impulse weight falls driven by gravity to a stop that the end of the shaft removed from the pliers is. This creates an impulsive force that only attacks in the short term, so that the burdens for the Patients are reduced.

The grippers are advantageously articulated on one Base body attached and a clamping ring is on the Basic body screwed on. The tension ring can pass through Turn to a blocking position that closes the gripper to be brought. The grippers are angular trained, the at the end of the long leg Gripping surface is arranged and the short leg Connection to the joint is made. The clamping ring works in  Corner area of the legs of the gripper on this. This Corner area is further from the axis of rotation of the Removal tool removed as the hinge. So it will Swiveling movement of the grippers with the help of the clamping ring generated. At the same time, the clamping ring blocks the grippers in its closed state.

In a further advantageous embodiment of the invention the insert indicates at least one to the carrier part open recess that is accessible to the gripper lies in the area of the recesses of the carrier part. The The gripper side of the extraction tool is essentially designed complementary to the recess of the insert, so that it can fit into the recess.

The following are exemplary embodiments of the invention explained in more detail with reference to the drawings.

Show it:

Fig. 1 a longitudinal section of the joint prosthesis and the puller tool,

Fig. 2 is a detailed view of the recess of the Trä gerteile and the gripper, and

Fig. 3 shows a further detailed view of the recesses in the carrier part and in the insert and an associated gripper.

Fig. 1 shows a joint prosthesis 1 and a pull-out tool 10. The joint prosthesis 1 consists of a spherical socket-shaped support part 2 , the inner surface of which is covered with a ceramic insert 3 . The inner surface of the insert 3 is also designed as a ball socket. It represents the sliding surface of the joint prosthesis 1. The insert 3 is fastened in the carrier part 2 by means of a conical clamping in the region of the clamping surface 6 . The carrier part 2 and the insert 3 have no contact in the region of the apex of the joint prosthesis 1 . The carrier part 2 is fastened in the bone with an anchor, which is not shown here. The insert 3 receives the counterpart of the joint on the opening side 4 . Furthermore, three recesses 5 are present in the inner surface of the carrier part 2 , which are arranged around the insert 3 in one plane. The recesses 5 are opened both towards the opening side 4 and for the insert 3 .

When the insert 3 is replaced, the joint prosthesis 1 is first exposed. The insert 3 is then removed with the aid of the extraction tool 10 .

The extraction tool 10 has an essentially cylindrical base body 11 and a shaft 12 . The base body 11 is equipped with an external thread 13 , to which a clamping ring 14 is screwed. Wei terhin joints 15 are attached to the joint prosthesis 1 to the side of the base body 11 . The axes of the joints 15 run transversely to the axis of rotation 20 of the extraction tool 10 . Grippers 16 with respective gripping surfaces 17 are fastened to these joints 15 . The gripping surfaces 17 are adapted to the conical outer surface 6 of the insert 3 . The base body 11 merges into a shaft 12 at the end facing away from the joint prosthesis 1 . At the end of the shaft 12 there is a stop 18 . A pulse weight 19 is guided on the shaft 12 between this and the transition region of the shaft 12 to the base body 11 .

To remove the insert 3 , the grippers 16 are first clamped to the insert 3 with the aid of the clamping ring 14 . The patient is then positioned so that the axis of rotation 20 of the extraction tool 10 is aligned vertically. This alignment is necessary so that the pulse weight 19 can generate the force for releasing the insert 3 . This is done by moving the pulse weight 19 on the shaft 12 in the direction of the insert 3 into an initial position. From there it falls on the stop 18, accelerated by gravity, and thus generates the required tractive force, which is pulse-shaped. This has the advantage that the force only acts for a very short time, so that the stress on the patient is reduced. The circumferentially distributed grippers 17 distribute the extraction pulse evenly, so that tilting of the insert 3 is avoided.

Fig. 2 shows a detailed view of the joint prosthesis 1 and a rapier 16 as. In this embodiment, the gripping surface 17 is L-shaped, the shorter leg gripping the edge 7 of the clamping surface 6 of the insert 3 . The recess 5 of the carrier part 2 is so wide that the gripper 16 can be inserted in the open state and then pivoted inwards.

Fig. 3 shows a detailed view of the joint prosthesis 1 and the rapier 16 as. The insert 3 has a recess 8 , which lies in the region of the recess 5 of the carrier part 2 . The gripping surface 17 of the gripper 16 has a tip 20 which forms the counterpart to the recess 8 of the insert 3 and can be pivoted into the latter.

Claims (5)

1. Combination of

• - A joint prosthesis ( 1 ), which has a pan-shaped support member ( 2 ), and an insert forming a joint shell ( 3 ) made of ceramic, and
• - A pull-out tool ( 10 ) for removing the insert ( 3 ) from the carrier part ( 2 ), with grippers ( 16 ) for engaging the insert ( 3 ),

characterized in that the carrier part ( 2 ) has at least one recess ( 5 ) open towards the opening side ( 4 ) of the joint prosthesis ( 1 ) and towards the insert ( 3 ), and that the grippers ( 16 ) can be inserted into the recess ( 5 ) and are pivotable against the insert ( 3 ), the grippers ( 16 ) gripping the edge of the insert ( 3 ). 2. Combination according to claim 1, characterized in that the extraction tool ( 10 ) has a shaft ( 12 ) on which a pulse weight ( 19 ) against a stop ( 18 ) is displaceable. 3. Combination according to claim 1 or 2, characterized in that the grippers ( 16 ) are attached to a base body ( 11 ) by means of a joint ( 15 ), and that a clamping ring ( 14 ) is screwed onto the base body ( 11 ), which can be brought into a blocking position by turning the grippers ( 16 ). 4. Combination according to one of claims 1 to 3, characterized in that the insert ( 3 ) at least one to the carrier part ( 2 ) towards the Ausneh mung ( 8 ), and that in this Ausneh mung ( 8 ) matching survey ( 20 ) of the gripper ( 16 ) can be swiveled in.