Protek Ag

Sulzer Brothers Limited

Gebruder Sulzer Aktiengesellschaft

Gebruder Selzer Ag

Maurice E Muller

Otto Frey

Roland Willi

Peter G Niederer

The plastic cup-comprising member and the hemispherical shell of the two-part acetabular cup prosthesis are secured relative to one another in snap-fitted manner. The plastic member is centered and guided during pressing-in via a centering pin and concentric annular web on the plastic member. The annular web is also locally deformable so as to deform against a screw head during pressing-in without the annular web losing its centering guiding action.

Acetabular cup prosthesis

The hip joint endoprosthesis has a plastic socket body with a hemispherical outer surface and a wire mesh metal grid partially embedded in the socket body surface. The metal grid has a plurality of rib-like projections extending outwardly along meridian lines of the socket body in order to define regions therebetween for receiving a minimum thickness of bone cement for anchoring of the endoprosthesis in a bone.

Endoprosthesis for a hip joint socket

The socket is made with a bowl having a spherical cap in the polar region and a part-spherical section which extends from the spherical cap on a larger diameter. The two sections join together at a distance from the top of the bowl socket which is 1/3 the diameter of the spherical cap while the diameter of the part-spherical section is from 1.02 to 1.10 times the diameter of the spherical cap. The diameters of the spherical cap and the part-spherical section intersect the axis of symmetry of the socket body, one on the equatorial plane and the other below the equatorial plane.

Artificial hip joint

A ruff or collar is positioned on the hip joint prosthesis shank prior to insertion of a prosthesis into a bone. The ruff can be slipped onto the straight shank in the direction of the longitudinal axis from the distal. The ruff is fixed to the transition region between the shank and the prosthesis neck by means of conical clamping surfaces. A set of ruffs may be provided each of which has a different thickness and/or different angle between the underside bearing surface and the top surface to accommodate inaccuracies in a resection cut.

Hip joint prosthesis

The injector is provided with an injection nozzle in the bottom of the cylinder tube for low pressure operation wherein large quantities of bone cement are to be injected. The injector also has a nozzle element which can be releaseably attached to the cylinder tube for high pressure injection. This nozzle element has a nozzle tube of reduced cross-sectional area through which a ram passes in the form of a piston in order to provide for high pressure injection.

Injector for bone cement

The prosthesis shank is composed of a blade which carries a joint head and a wedge-shaped end piece. The end piece is driven in along a guide in the lateral narrow side of the blade while the blade remains in a fixed position. The wedge-shaped form of the end piece permits fixation of the blade at a predetermined height such that the joint head can be at the level of the trochanter tip.

Shank for a prosthesis

To obtain an increase of the lateral distance between the longitudinal median axis of the straight prosthesis shank and the center of the joint head, the straight shank has a tapered medial side which changes over to an arcuate side on an arc of a circle which connects the transition point with the point of the smooth passage of the medial side into the prosthesis neck and with the center of the joint head. The angle between the longitudinal median axis and the prosthesis neck axis remains unchanged. This results in a lateral distance enlargement without having to shift the relative height position of the point at which the curved shank side meets the neck in the body, i.e., relative to the muscle origins.

Growing community of inventors

Bern, Switzerland

Maurice E Muller