DE3119130A1 - Acetabulum for hip endoprostheses - Google Patents

Abstract

An acetabulum for hip endoprostheses for isoelastic, self-adhering, cementless implantation in a recess in the pelvic bone, which comprises a hemispherical or cap-shaped acetabular body (1) with approximately radially directed passage openings (9), is to be improved in terms of its long-term strength and permanent vibration resistance. For this purpose, the passage openings (9) are designed as outwardly widening funnels and are arranged in large numbers close to one another and offset in gaps such that the funnel edges of adjacent passage openings touch one another where possible. This perforated design of the acetabulum creates numerous attachment cavities into which the bone can grow in the course of time, the funnel-shaped design of these attachment cavities permitting the growing-in bone material to develop the usual physiological bone structure, i.e. in the wide areas of the attachment cavities a multiply braced framework composed of small trabeculae, whereas it develops the usual compact tissue surface inwardly towards the boundary layer. <IMAGE>

Description

Patent and utility model registration

Joint socket for hip joint endoprostheses The invention relates to a Self-adhesive, cementless implantable joint socket for hip joint prostheses for implantation in a pelvic bone recess, which consists of a hemispherical, or dome-shaped pan body with approximately radially directed through holes consists.

In a known such joint socket (DE-OS 29 11 754) are a few, narrow through-holes are provided, which have the task of providing tissue water to derive or to increase the degree of wetting. The well-known socket is in the the rest of the thick-walled solid and on the outer surface with concentric, ring-shaped nailing edges that provide immediate mechanical rest Ensure the implanted socket, so that the prosthesis immediately after the operation functioning and is fully resilient. In the known prosthesis there are between the nailing edges Prison rooms, in which the bone can later sprout, which fixes one in the long run continued mechanical rest is vital. The well-known prosthesis has proven itself to be excellent, but is in terms of long-term strength and the fatigue strength, i.e.

The elasticity of the prosthesis can still be improved, which is the task of the present invention.

Starting from a joint socket of the type mentioned, the This object is achieved according to the invention in that the through holes designed as an outwardly widening funnel and in large numbers Gap offset, are arranged close together and that the funnel edges are adjacent Through holes touch each other. This perforated design of the joint socket Numerous cells are created into which the bones sprout over time can. As a result of the funnel-shaped design of these detention rooms, the ingrown Bone material corresponds to the usual physiological structure of bones train, i.e. in the large areas of the detention rooms as a multi-braced framework the end small trabeculae, while it moves inward to the boundary layer develops as the usual compact bone surface. The prosthesis met the function of the trabeculae growing on them, corresponding to each other organize the tension and pressure conditions changing from mm2 to mm differently, with their funnel-shaped openings and collect the resulting bone structures to connect with each other and thus to simulate the process that occurs naturally in the bone compact. By taking into account the natural structural conditions In the case of bones, the socket is embedded in a quasi-elastic manner in the bone material achieved, reducing the risk of shrinkage of the bone under pressure is largely prevented. In the invention, the entire pan wall is one thick boundary layer, within which the prosthesis and bone material are mutually exclusive penetrate, with the proportion of prosthesis material over the wall thickness of the socket decreases evenly in favor of the bone material. As a bone boundary layer The more the prosthesis works in terms of fatigue strength, the more it works the overall elasticity of the socket material and socket embedding match those of the baby tissue. The bone tissue is in this relationship however, it is not a homogeneous fabric, so that it is not possible from the outset to find a material isoelastic prosthesis to manufacture. It can therefore only be the total elasticity (from the socket and socket embedding) in agreement with that of the bone tissue be brought, with the special type of force introduction in the present case serves as a regulator. This means that the elasticity of the pan material is more than that of the Contrasted bone tissue of the socket, the more that will be in the Reinforce the trabeculae that are injected into the prosthesis in whole or in sections or weaken.

The sieve-like loosening of the wall of the prosthesis finally makes it this permeable to metabolic processes in both directions, so that in particular the tissue fluid is not in a connective tissue as in the closed prosthesis Granulation seam around the prosthesis has to find a way. So this one falls Layer of tissue gone, which is not stable and which is the cause of many prosthesis loosening must be viewed.

The joint socket can either be made of a single material or consist of several chemically or physically connected components. The material is to be considered suitable if it has the following properties: biocompatibility, Strength, sliding friction properties and modulus of elasticity according to the latest standard.

According to a preferred embodiment of the invention, provision can be made be that between three touching with their edges through holes each a funnel-shaped blind hole is provided, which with its edge also the Touches the edges of the three through holes. This creates even more cells created for injecting bone material and on the other hand a sharp-edged, rough surface of the acetabulum reached what is in terms of an immediate mechanical Rest in the denture store is an advantage.

A favorable ratio of detention space for injected bone to Prosthetic material is achieved when the diameter of the external openings the through holes is approximately equal to the length of the through holes.

According to further features of the invention it can be provided that the through holes within an inner wearing layer of the socket body are designed as narrow cylindrical channels. This ensures that even with a certain amount of abrasion, the bearing surface formed by the prosthesis material Pan maintains its size.

Finally, according to the invention, it can also be provided that the pan body is onion-shaped and has a tip at its zenith having.

Here, the pan body is expediently interrupted outer anti-twist ribs, which radiate around the point of impact are distributed. As a rule, these measures result in a cement-free implantation because an immediate mechanical rest is guaranteed.

The joint socket according to the invention is described below with reference to the drawing explained in more detail. In the drawing, FIG. 1 shows an acetabular cup in side view in a simplified representation, FIG. 2 is a plan view of the joint socket according to FIG. 1, FIG. 3 a detailed plan view of a modified embodiment of a joint socket and 4 shows a partial section through the pan wall.

The joint socket consists of a shell-shaped socket body 1, whose inner surface 2 is hemispherical and whose outer surface 3 is onion-shaped. in the At its zenith, the socket body has an attachment point 4 and several, radial-shaped As a rule, single-row, interrupted anti-rotation ribs distributed around the tip 4 5, 6, 7, 8 and / or a circumferential ring of nailing knobs 13, which as sharp-edged cutting edges are formed.

In between the nailing tip 4 and the nailing blades lying fields is the pan body 1 with a large number of outward through holes 9 widening in the shape of a funnel, which in FIG. 2 only is fully excellent for a field. The holes 9, which are predominantly in the drawing are only indicated by dots, are strung along concentric rings so closely together that that their funnel edges touch.

The through holes are staggered from ring to ring, whereby the funnel edges of through holes of adjacent rings also touch.

As can be seen from Fig. 3, in the small, between three adjacent through holes 9 lying island surfaces still further smaller funnel-shaped Blind holes 10 may be provided.

Fig. 4 shows a partial section through the wall of the socket body 1. The through holes 9 are inside half of an inner wearing layer 11 designed as narrow cylindrical channels 12. The diameter rt D of the outer, large openings of the funnel-shaped through holes 9 is approximately equal to the wall thickness of the socket body 1.

In Fig. 4 are dashed lines according to the alternative embodiment According to FIG. 3, blind-hole-like funnel openings 10 that can still be provided are shown.

The socket body can be made in one piece and homogeneously. Likewise is it possible to # the pan body in multiple layers of the same or different shells Material to build up, the shells by chemical or mechanical means are attached to each other.

Claims (9)

Patent claims joint socket for hip joint prostheses for cementless, self-adhesive implantation in a pelvic bone recess, consisting of a hemispherical or dome-shaped socket body with approximately radially directed through holes, characterized in that the through holes (9) as expanding outwards Funnels are formed and arranged in large numbers close to one another. 2. joint socket according to claim 1, characterized in that the funnel-shaped Through holes (9) are arranged offset next to one another with a gap. 3. joint socket according to claim 2, characterized in that each touch the funnel edges of three adjacent through holes (9). 4. joint socket according to claim 3, characterized in that between three through holes (9) touching one another with their edges, each a funnel-shaped Blind hole (10) is provided, which with its edge the edges of the three through holes touched. 5. Joint socket according to one or more of the claims. 1 to 4, characterized in that the diameter (D) of the outer Openings of the through holes (9) approximately equal to the length of the through holes is. 6. joint socket according to claims 1 to 5, characterized in that that the through holes (9) within an inner wearing layer (11) of the socket body are designed as narrow cylindrical channels (12). 7. joint socket according to one or more of the preceding claims, characterized in that the pan body (1) is onion-shaped and has a point of impact (4) in its zenith. 8. joint socket according to claim 7, characterized in that the socket body (1) provided with external, interrupted anti-twist ribs (5, 6, 7, 8) is, which are distributed radially around the impact tip (4). 9. joint socket according to claim 7 or 8, characterized in that the socket body (1) with a surrounding ring of sharp-edged nailing knobs (13) or nailing tips.