DE4428407A1 - Artificial joint, especially to replace the human hip joint - Google Patents

Abstract

An artificial joint, in particular for replacing the human hip joint, consists of a joint head (1) with a convex circular contour, of a joint socket (2) with a concave circular contour and of a pressure distributing body (3) slidingly arranged between both functional surfaces. The sliding surfaces of the pressure distributing body (3) that lie on the functional surfaces have a curvature adapted to the functional surfaces. The pressure distributing body (3) has a thickness (d) along the line that interconnects the rotation centres of both circular contours of the head (1) and socket (2). The swivelling range of the joint head (1) in the front plane Z-Z perpendicular to the main functional direction Y-Y is smaller than 180 DEG and preferably equals about 120 DEG .

Description

The present invention relates to an artificial joint, especially to replace the human hip joint, consisting of a joint head with a convex, circular Cutting contour with the center M₁ and the radius R₁ and a socket with a concave, circular sectional cone tur and the center M₂ and the radius R₂ and one sliding between these two on their functional surfaces arranged pressure distribution body, the adjacent Sliding surfaces according to the functional surfaces have a matching curvature, and the pressure distribution body a thickness d on the line connecting the centers of rotation M₁ and M₂ of the two circular sectional contours of Joint head and the socket.

Such an artificial joint is from the German Patent application P 39 08 958.4-35 known. This is about it is an artificial joint, its joint parts are dimensioned such that it is a pressure stable Joint with five degrees of freedom. With this joint the individual joint axes form a dimeric joint chain, where the radius of the articulated axis path R is as follows calculated:

R = R₂ - R₁ - d.

The radii R₂ and R₁ are dimensioned such that R₂ < R₁ + d is. With this joint there is a risk that the Luxate the pressure distribution body from the socket, d. H. can move out if the condyle is extreme Performs swivel movements.

The present invention has for its object that artificial joint described in the beginning to be so verbes that a dislocation of the pressure distribution body from the Joint socket is not possible. At the same time, however easy assembly of the artificial joint, in particular when inserted into the human body accomplishes.

According to the invention this is achieved in that the Ge Steering pan has such a peripheral edge that the artificial joint in its main functional direction vertical frontal plane a swivel range of the joint Head has less than 180 °, preferably about 120 ° is. According to the invention, this limitation of Swivel range causes the pan edge deviating from the equatorial circumference of the joint pan at least one preferably in the frontal plane wave-shaped elevation, especially two diametrically opposite elevations above the circumference owns. Through these wave-shaped elevations above the equatorial circumference is prevented from Pressure distribution body from the socket can luxate. According to the freedom of movement of the disc in the The main function direction is therefore larger than that in the lower one right level, d. H. in the frontal plane. Between  two wave-shaped, diametrically opposite Elevations of the joint socket according to the invention become a Slit formed, which allows for operations the pressure distribution body through this into the Insert the socket. This insertion through the slot through with one movement and in one position Discus that this no longer after attaching the Conduct or take joint head.

It is also advantageous according to the invention if the joint pan has such a circumferential edge that the Joint in its main function direction a swivel rich or greater than or equal to 180 °. The extension of the The pivoting range is advantageously achieved by that the socket is different from its equatorial Perimeter line based on a semicircular cut contour has such a pan edge course that in Area between the two surveys in the main radio direction at least one particular wave valley-shaped indentation is provided. Are preferred two diametrically opposed indentations are formed. These indentations also allow the insertion of the Pressure distribution body in the socket, if the Discus, which is advantageous with its outer radius corresponds to the inner radius of the socket and thus up to about the equatorial circumference of the socket is pulled up.

Further advantageous embodiments of the invention are in the Subclaims included.

Using that shown in the accompanying drawings The embodiment is explained in more detail.  

Show it:

Fig. 1 is a perspective view of a fiction, modern artificial joint in nichtmontiertem state,

Fig. 2 is a perspective view of a modern fiction, joint socket,

Figure 3 is a perspective view of a body lung Druckvertei.,

FIG. 4 shows a section through an acetabular cup according to FIG. 2 with an inserted pressure distribution body and

Fig. 5 shows a section through an inventive joint in its functional position.

In Fig. 1 it is shown that an inventive artificial joint of a socket 2 and a joint head 1 and a pressure distribution body 3 is formed. The joint head 1 has a convex, circular cutting contour, so that a joint head ball is formed, which is flattened in the region of its shaft attachment 1 a. The joint socket 2 also has a circular sectional contour, so that a shell-shaped, semi-circular cross-sectional shell body is formed. This shell body has an equatorial circumferential line X. The pressure distribution body 3 is designed such that its sliding surfaces 6 , 7 on the functional surfaces 4 , 5 , ie the functional surface 4 of the socket 2 and the functional surface 5 of the joint head 1 , so that its sliding surfaces 6 , 7 have a correspondingly adapted curvature to the respective functional surfaces 5 . With regard to the design of the artificial joint, reference is made to the German patent application P 39 08 958.4-35, in particular FIG. 3 with the associated description. The joint head 1 has, see Fig. 5, the center of rotation M₁ and the radius R₁ and the socket 2 has the center of rotation M₂ and the radius R₂. The pressure distribution body 3 has a thickness d on the connecting line of M₁ and M₂. The joint parts designed in this way form a dimeric joint chain with two joint axes by M₁ and M₂ in the inserted state, the radius R of the joint axis path being obtained from the relationship

R = R₂ - R₁ - d, where R₂ <R₁ + d.

This configuration of the artificial joint requires a pressure-stable joint behavior in every bending or pivoting position of the joint head 1 .

According to the invention, it is now provided that the socket 2 has a peripheral edge 8 such that the joint according to the invention in its frontal plane ZZ perpendicular to the main functional direction YY has a swivel range which is less than 180 °, preferably approximately 120 °. This is achieved in that the pan edge 8, deviating from the equatorial circumferential line X in the frontal plane ZZ, has at least one in particular wave-shaped elevation 9 , preferably two diametrically opposite, wave-shaped elevations 9 . Furthermore, it is expedient if the joint according to the invention has a pivoting range greater than 180 ° in its main functional direction YY. This expanded swivel range is caused by the fact that the joint socket 2 forms at least one, in particular, wave-shaped indentation 10 in the region of the main functional direction. Preferably, two diametrically opposed, trough-shaped indentations 10 are formed. As can be seen in particular in FIG. 5, the pressure distribution body 3 advantageously has an outer radius which, apart from an existing lubrication clearance, corresponds to the radius R 2, ie the inner radius of the socket 2 . In Fig. 4 it is shown how the Druckver distribution body 3 can be inserted through the slot formed between the wave-shaped elevations 9 in the region of the wave-shaped indentations 10 in the socket 2 . However, the disc or pressure distribution body 3 due to the inventive limitation of the swivel range in the frontal plane ZZ and the associated expansion of the socket 2 over the equato rial circumferential line X also not with a possible luxation of the joint head 1 from the socket 2 ren. Furthermore the joint parts according to the invention are dimensioned such that the diameter of the joint head 1 is smaller than the distance between the opposing wave-shaped elevations 9 , so that the joint head 1 can be used in any case from the open side of the joint socket 2 .

Furthermore, it may be advantageous if the joint head 1 to the equator toward XX from the disc, that is, from Druckver partition body 3 is covered, where the pressure distribution is circumferentially pulled body 3 by a portion 11 to the equator. In addition, in a further implementation of the pressure distribution body 3 in the area from section 11 to the joint head 1 can be expanded cylindrically. This additionally complicates luxation of the joint head 1 with respect to the pressure distribution body 3 .

The present invention is not limited to the embodiment shown. So it may be possible within the scope of the invention if the restriction of the swivel range of the joint head 1 in the frontal plane is partially realized by a union which can be screwed onto the socket 2 .

Claims (8)

1. Artificial joint, in particular to replace the human hip joint, consisting of an articulated head ( 1 ) with a convex, circular cutting contour and an acetabular cup ( 2 ) with a concave, circular cutting contour and a pressure distribution body ( 3 ) slidably arranged between the two functional surfaces. , the sliding surfaces of which lie on the functional surfaces have a curvature which is matched to the functional surfaces and the pressure distribution body ( 3 ) has a thickness d on the line connecting the centers of rotation of the two circular cutting contours of the joint head ( 1 ) and the joint socket ( 2 ), characterized in that in the front valley plane ZZ perpendicular to the main functional direction YY, the swivel range of the joint head ( 1 ) is less than 180 °, preferably approximately 120 °. 2. Artificial joint according to claim 1, characterized in that the joint socket ( 2 ) has a semicircular sectional contour with an equatorial circumferential line X, deviating from the equatorial circumferential line X in the frontal plane ZZ at least one preferably wave-shaped mountain-shaped elevation ( 9 ) above the circumferential line is trained. 3. Artificial joint according to claim 2, characterized in that two diametrically opposite elevations ( 9 ) are present. 4. Artificial joint according to one of claims 1 to 3, characterized in that the joint socket ( 2 ) has such a circumferential edge ( 8 ) that the joint in its main functional direction plane YY has a swivel range greater than / equal to 180 °. 5. Artificial joint according to claim 4, characterized in that the socket edge ( 8 ) in the area of the main functional direction YY plane at least one in particular wave-shaped indentation ( 10 ), preferably two diametrically opposite indentations ( 10 ), below the equatorial circumferential line X owns. 6. Joint according to one of claims 1 to 5, characterized in that the pressure distribution body ( 3 ) with its outer radius in the basic position up to the equatorial circumferential line X of the socket ( 2 ) is raised. 7. Joint according to one of claims 1 to 6, characterized in that the joint head ( 1 ) up to its equator from the Druckver distribution body ( 3 ) is covered in the basic position. 8. Joint according to claim 6, characterized in that the pressure distribution body ( 3 ) up to the equator XX of the socket ( 2 ) is pulled up by an extension section ( 11 ), in this extension section from ( 11 ) the functional surface to the joint head ( 1 ) is cylindrical in shape.