Abstract: The invention relates to a positioning instrument (1) for inserting an extension shell (2) into a human or animal bone, especially a pelvic bone. Said instrument comprises a fixing device (18) for fixing the extension shell (2) to the positioning instrument (1), and a displacement device (55) for displacing a disc element (15) of the positioning instrument (1) at least essentially axially in relation to the extension shell (2) fixed to the fixing device (18). Said disc element (15) co-operates with beveled surfaces (25a to 25e) of the extension shell (2) during the displacement, in order to tighten the extension shell (2). Furthermore, the disc element (15)-viewed in the direction of insertion (13)-does not project beyond the radially furthest projecting elements (32a, 32b) of the tightened extension shell (2).

Abstract: The invention relates to an expandable socket (1) for a hip joint endoprosthesis able to be cementlessly anchored in place which is at least approximately hemispherical and which is provided with a plurality of slots (3) extending in a meridional direction, thus forming intervening tongues (4), on which are formed projections (5) that form a plurality of rows (6; 6a, 6b) extending from an equator (2) of the expandable socket (1). The projections (5) are arranged on the tongues (4) in such a manner that a row (6a) of projections (5) arranged in the center of the tongue (4) extends on a meridian (14) of the hemispherical socket (1) while at least one adjoining row (6b) of projections (5) extends in a line that extends at all points in parallel to the meridian (14) of the row (6a) of projections (5) arranged in the center and not through a pole (10) of the hemispherical expandable socket (1).

Abstract: The invention relates to an expandable socket (1) for a hip joint endoprosthesis able to be cementlessly anchored in place which is at least approximately hemispherical and which is provided with a plurality of slots (3) extending in a meridional direction, thus forming intervening tongues (4), on which are formed projections (5) that form a plurality of rows (6; 6a, 6b) extending from an equator (2) of the expandable socket (1). The projections (5) are arranged on the tongues (4) in such a manner that a row (6a) of projections (5) arranged in the centre of the tongue (4) extends on a meridian (14) of the hemispherical socket (1) while at least one adjoining row (6b) of projections (5) extends in a line that extends at all points in parallel to the meridian (14) of the row (6a) of projections (5) arranged in the centre and not through a pole (10) of the hemispherical expandable socket (1).

Abstract: The invention relates to a positioning instrument (1) for inserting an extension shell (2) into a human or animal bone, especially a pelvic bone. Said instrument comprises a fixing device (18) for fixing the extension shell (2) to the positioning instrument (1), and a displacement device (55) for displacing a disc element (15) of the positioning instrument (1) at least essentially axially in relation to the extension shell (2) fixed to the fixing device (18). Said disc element (15) co-operates with beveled surfaces (25a to 25e) of the extension shell (2) during the displacement, in order to tighten the extension shell (2). Furthermore, the disc element (15)-viewed in the direction of insertion (13)-does not project beyond the radially furthest projecting elements (32a, 32b) of the tightened extension shell (2).

Abstract: A femur component of a hip joint endoprosthesis which has a shaft (1) for anchoring in the medullary cavity of the femur. The shaft (1) has a distal section (9) and a proximal section (8), to which is connected a collar section (2) with a peg (3) for receiving an articular head, or with an articular head which is firmly attached to the collar section (2). The shaft (1) has a front surface (4), a rear surface (5), a lateral side (6), a mesial side (7) and a plane of symmetry (11), whereby longitudinal ribs (10) which stretch from proximal to distal are fitted on the front surface (4) and the rear surface (5) in the proximal section (8) of the shaft (1). The crests (12) of the longitudinal ribs (10) form an angle &dgr;/2 of at least 1° to the plane of symmetry (11), and the envelope of the crests (123) of the longitudinal ribs (10) forms a double wedge-like or ellipsoid body, which tapers both toward the lateral side (6) and the mesial side (7).

Abstract: A intramedullary nail of the type adapted to receive a conical drive connection is provided with a slot which extends from the tip to the head for improved elasticity. A locking section is provided at the head to avoid the nail spreading apart when a conical drive connection is used. The nail has a threaded conical socket to receive a drive connection and the thread is shaped to minimize radial forces resulting from driving bolt being screwed into the socket.