Title:
ARTIFICIAL HIP JOINT
United States Patent 3610235


Abstract:
An artificial hip joint is intended for use in arthroplasty and comprises an acetabulum prosthesis and an artificial caput femoris interconnected for relative movement with one another. The femoral neck is radially curved and tapered, and is disposed eccentrically in relation to a support plate for the prosthesis.



Inventors:
VAGACS HANNES
Application Number:
04/737910
Publication Date:
10/05/1971
Filing Date:
06/18/1968
Assignee:
SEMPERIT OSTERREICHISCH - AMERIKANISCHE GUMMIWERKE AG.
Primary Class:
Other Classes:
128/DIG.20
International Classes:
A61F5/058; (IPC1-7): A61F5/04
Field of Search:
128/92C,92CA,92BB,92F,92B,92BA,92,92R 3
View Patent Images:
US Patent References:
2785673Femoral prosthesis1957-03-19Anderson



Foreign References:
FR1506594A
SU124585A1
Other References:

Earl D. McBride, A Metallic Femoral Head Prosthesis for the Hip Joint, Journal of the International College of Surgeons, Vol. XV, No. 4, April 1951, pp. 498-503 Journal of Bone & Joint Surgery, p. 61, advertisement by DePuy Mfg. Co., Inc..
Primary Examiner:
Gaudet, Richard A.
Assistant Examiner:
Mitchell J. B.
Claims:
What is claimed is

1. An artificial hip joint for use in arthroplasty comprising a prosthesis of the acetabulum and a prosthesis of the caput femoris movably interconnected with each other; said prothesis of the caput femoris including an intraosseous rod, a curved neck constituting an extension of said intraosseous rod and diminishing in thickness in a direction away from said intraosseous rod, and a disc-shaped portion of increased thickness at the juncture of said intraosseous rod and said neck, said curved neck having a central axis which is eccentric with respect to the central axis of said intraosseous rod and an outer edge of said neck coincides with and edge of said disc-shaped portion, said disc-shaped portion having an opening in the side thereof opposite the point of coincidence of the outer edge of said neck and the edge of said disc-shaped portion and extending perpendicularly to the axis of said intraosseous rod, said opening being adapted to accommodate a further rod for securing the trochanter major in the course of operation.

2. An artificial hip joint as claimed in claim 1, comprising a washer and bush on said intraosseous rod below said disc-shaped portion, said washer having a larger diameter than the diameter of the disc-shaped portion.

Description:
The present invention relates generally to artificial joints used for intra-articular application and more specifically to an artificial hip joint utilized in arthroplasty.

Artificial hip joints of the prior art are now employed in arthroplastic operations, comprising metal prosthetic structures, i.e., the artificial acetabulum and the artificial caput femoris, both of said structures being articulately interconnected. The acetabulum prosthesis is essentially a cup-shaped hollow or socket on its outer surface carrying lobes with marginal incisures. The artificial caput femoris consists of a ball-shaped head, a neck and an intraosseous rod, said neck connecting said head with said rod at an angle corresponding to the collodiaphytic angle so that the femoral neck is laterally conjugated with the rod and makes up a conjugate angle with the latter approximating the right one.

Though the application of the aforedescribed artificial hip joints in the up-to-date surgical practice has yielded good results the same surgical practice has made evident some disadvantages inherent in said artificial hip joints which result from an imperfect shape of the prothesis. As a result, breakage of the prosthesis has occurred in some cases at the place of conjugation of the femoral neck with the rod.

An object of the present invention is to provide an artificial hip joint adapted for use in arthroplasty which will perform all functions inherent in a normal human hip joint and possess a sufficient strength and service life.

With this and other objects in view, in an artificial hip joint incorporating movably interconnected an acibulum prosthesis and an artificial caput femoris with a curved neck adapted to be conjugated with an intraosseous rod, according to the invention, said curved femoral neck is in effect an extension of said intraosseous rod which has a disk-shaped portion of increased diameter located at the place where said rod goes into said neck so that the base of the neck coincides with the butt end of said disc-shaped portion, whereas a tangential line to axis of the neck makes up a small acute angle with the axis of said rod.

It would be better that the base of the femoral neck be disposed eccentrically with respect to the intraosseous rod so as to be offset towards the curvature of the neck and that the edge of the neck base located on its curved-in side be in coincidence with the edge of the disc-shaped portion of the rod.

It is likewise advantageous that a bushed washer be fitted onto said rod below the disc-shaped portion thereof, the diameter of said washer being greater than that of said disc-shaped portion.

The aforementioned design features of the artificial hip joint of the invention make it possible to reliably and securely interconnect both the acibulum prosthesis and the artificial caput femoris with the coxofemoral bones of the patient, whereby the prosthetized joint is free to quickly restitute its normal supporting function and the term of treatment of patients is substantially reduced.

In what follows is the nature of the present invention as explained in the disclosure of its exemplary embodiment given by way of illustration to be taken in conjunction with the accompanying drawing.

FIG. 1, representing a diagrammatic view of an artificial hip joint taken in a fragmentary longitudinal section with a number of cutaways.

FIG. 2, a section taken along lines II--II in FIG. 1; and

FIG. 3, a view taken along arrow B in FIG. 1.

Now referring to the drawing, the artificial hip joint comprises articulately interconnected an acibulum prosthesis 1 and an artificial head 2 of the femur with a curved femoral neck 3 which is conjugated with an intraosseous rod 4.

The curved femoral neck 3 is essentially an extension of the intraosseous rod 4 so that a tangential line to the axis of the neck makes up a small acute angle with the axis of the rod. The rod 4 has a disc-shaped portion 5 of increased diameter located at the place where it goes into the neck 3. A base 6 of the neck 3 is disposed eccentrically with respect to the intraosseous rod 4 so as to be offset towards the curvature of the neck in FIG. 2. Moreover, the edge of the base 6 of the neck is in coincidence with the edge of the disc-shaped portion 5 of the rod 4.

The disc-shaped portion 5 on its outer circumferential surface has an opening for a rod 7 to fix the trochanter major. The intraosseous rod 4 is cone shaped to suit the shape of the medullary canal of the femur.

A washer 8 with a bush 9 is fitted onto the intraosseous rod 4 below the disc-shaped portion 5, the diameter of the washer 8 exceeding that of said portion 5 so as to reliably fix the top end of the intraosseous rod 4.

Provision is made in the lower third of the intraosseous rod 4 for two apertures arranged in the frontal plane thereof as shown in FIG. 3. The final securing of the intraosseous rod 4 is assumed to occur by virtue of ingrowing of the bony tissue into said apertures.

The exterior surface of the acetabulum prosthesis 1 is mushroom shaped with four partially spherical projections 10 arranged one above the other.

The interior articular surface of the acetabulum prosthesis 1 has a through-profiled depression to accommodate a split bush or insert 11 which envelops more than half the artificial head 2 of the femur.

The application technique of the aforedescribed artificial hip joint is as follows:

First the upper end of the femur is exposed by making a straight lateral incision. Then the trochanter major is cut off by a chisel and displaced upwards together with the muscles attached thereto. Thereupon the femur is cut transversely by a chisel at the level of the lower edge of the trochanter minor.

Next the caput femoris together with the collum femoris is ablated by a grooved chisel, whereupon the femoral medullary canal is treated with a tapered burr shaped so as to suit the shape of the intraosseous rod 4 of the prosthesis being applied. Then the acetabular fossa of the patient is treated with a mushroom-shaped burr whose diametral size is 3 mm. less than that of the spherical projections 10 of the acetabulum prosthesis 1. Further the intraosseous rod 4 of the prosthesis is inserted into the bulk of the femur by using a brace and a mallet. Thereupon the acetabulum prosthesis 1 is introduced into the pretreated acetabular fossa perpendicular to the plane of entrance thereof; while introducing the prosthesis, it is turned by means of a special turning handle and, by tapping with a mallet, the prosthesis is caused to assume such a position that its surface facing the femoral neck 3 be in the same plane with the entrance into the acetabular fossa. Thus, due to the different diameters of the acetabulum prosthesis 1 and the acetabular fossa of the patient, the edges of the spherical projections 10 are free to force their way into the spongy osseous tissue of the walls of the acetabular fossa, whereby a strong and reliable fastening of the prosthesis to the acetabular bones is attained. Then the previously cutout trochanter major is made fast to the exterior surface of the upper end of the femur by means of the rod 7, whereupon the wound is stitched layer-upon-layer until getting tightly sutured.