The invention relates to a prosthesis assembly, comprising an outer stem (10) provided with a proximal opening (11), and at the distal end (12) thereof is provided with a connecting means (13) for fastening an additional component, and which is formed of a material that is rigid in the longitudinal extension thereof, in which at least one slit (14) extending at least partially in a longitudinal direction is inserted in order to allow deformation in a radial direction. The prosthesis assembly further comprises an inner stem (20) made of a flexible material and provided with a proximal opening (21), at least one tensioning device (30) that is affixed to the outer stem (10) and can be accessed by way of a diameter change of the outer stem (10). At least one electrode (40) is displaceably fastened to a side of the outer stem (10) that is facing the inner stem (20).
