Abstract: A tubular guide part which is insertable into the medullary space is connected to a source of pressure medium and to a blocking element having the form of a hollow body which can be inflated in the manner of a balloon. The hollow body is inflated via the supply of pressure medium from a basic position situated in the cross-sectional region of the guide part into an expanded position in which the hollow body seals off one portion of the medullary space, which is to be filled with bone cement and is to receive a prosthesis shaft, from a neighboring portion of the medullary space. After insertion of a part of the prosthesis shaft into the bone cement bed, the hollow body can be shrunk into its basic position by the removal of pressure medium and withdrawn from the medullary space together with the guide part. The cavity in the bone cement bed ensuing therefrom is filled up by bone cement expelled during insertion of the remaining portion of the prosthesis shaft.

Abstract: The invention relates to an artificial joint shell having an outer shell (2) which is implantable in a bone base and a retro-fittable inner shell (3), the inner and outer shells being fixable to one another via a friction-locked clamping force (5), preferably via a self-locking, conical connection. A tunnel (6) is formed in the partition surface (4) between the two shells (2, 3) and connects two points at the shell edge in an arc (37) that extends towards the shell base (7). A wire (8) is threaded through the tunnel (6), and by applying an extraction force to the wire the inner shell (3) is extracted. The extraction force is uniformly applied to the inner insert along the arc (37) prescribed by the tunnel and does not damage the inner shell.