The invention relates to a prosthesis for at least partial replacement of a tubular bone and of an adjacent joint, comprising an elongate shaft (1) with a first end and a second end, and a joint mechanism (2) arranged at the second end of the shaft (1), wherein a length-adjusting mechanism (3) is provided which actuates the shaft (1) along the axis (10) thereof in the manner of a telescope. The shaft (1) and the joint mechanism (2) are coupled via a plug connection with matching cone connectors (18, 29), wherein the length- adjusting mechanism (3) is of a modular design and, at the proximal and distal ends thereof, is provided with the matching cone plug connectors (18, 19), and it is further provided with an anti-rotation means (35, 37) that acts with a form fit.
