Sulzer Brothers Limited

Sulzer Orthopaedie Ag

Feldmuhle Anlagen- Und Produktionsgesellschaft MIT Beschrankter Haftung

Zimmer Gmbh

Manfred Semlitsch

Otto Frey

Heinz Weber

Hans-Georg Willert

Erhard Doerre

Erhard Dorre

Artificial joint, particularly an artificial hip joint

A metal grid is embedded in the contact surface of a plastic implant in order to increase the wear resistance of the plastic implant. The ridge dimensions of the metal grid are chosen so that the elasticity of the plastic implant is not unduly reduced. An additional anchoring surface formed of layers of porous metal may be secured to the embedded grid to provide a surface into which bone tissue may grow in a cementless anchorage.

Plastic bone implant having a reinforced contact surface

The porous metal overlay for an implant surface is comprised of a plurality of layers of stacked metal grids. Each layer is provided with pores which are of a size which decrease in the direction of the implant surface steadily, that is, without enlargement in an intermediate layer. The progressively decreasing porous sizes provide for a steady ingrowth and nourishment of the ingrowing tissue.

Porous metal overlay for an implant surface

The femoral head prosthesis has a straight fixing stem for implantation in a femur which is provided with a longitudinal bore which extends along the axis of the stem. The stem can be slid along a centering rod previously positioned within a surgically prepared bone cavity of the femur to guide the stem into a bone cement bed. The centering rod is initially put in place with a cavity barrier followed by placement of the bone cement bed. After initial curing of the bone cement, the rod can be disengaged from the cavity barrier and removed from the stem.

Prosthesis for a femoral head

The metal bone implant is constructed with thin sheets of superplastic material which are deformed into irregular contours. The sheets are welded to the solid base element of the implant and thereafter deformed outwardly under fluid presure to an irregular shape.

Method of making a metal bone implant

The metal bone implant is constructed with thin sheets of superplastic material which are deformed into irregular contours. The sheets are welded to the solid base element of the implant and thereafter deformed outwardly under fluid pressure to an irregular shape.

Metal bone implant

The prosthesis consists of a sheet metal shell which is formed of two shell parts or half shells to form a closed hollow body. The thickness of the hollow body is in the range of from 1 to 3 millimeters. In addition, the hollow body may be provided with internal supporting elements to rigidify the shell and/or with a filling of an elastic or plastic material.

The metal male joint part has a taper which is less than that of the cavity of the oxide ceramic female joint part. In addition, the surface of the male part has a resistance to deformation which is less than that of the core of the male part. The cone angle .beta. of the female cavity and the cone angle .alpha. of the male joint part are in the relation:

Joint endoprosthesis

An artificial head assembly for a human femur consists of the head portion roper and a metal pin. The head portion is a sintered ceramic ball having a polished contact face of convex, spherical curvature and a blind bore tapering conically inward toward the contact face. The pin is shaped for insertion of one end into the hollow stump of the femur, the other end tapering conically at the same apex angle as the bore in the ball. A knurling of the conical face of the pin reduces the compressive strength of the pin surface to less than the tensile strength of the ball so that the assembled head and pin can be sterilized without cracking the ceramic head portion because of differences in coefficients of thermal expansion between the metal and the ceramic material.

Growing community of inventors

Winterthur, Switzerland

Manfred Semlitsch