Femoral shaft prosthesis with a proximal centralizing device

Prosthesis femoral stem (1) cementable with a neck (2) of prosthesis with a stem (3) and a proximal centering device (4) which can be introduced with the shaft (3) in a cavity (5) of bone, wherein the stem (3) is a rod collarless because the centering device (4) can be engaged from medial onto the shaft in the cemented region and has at least medially one centering wedge ( 6) which widens towards proximal and which is connected by ribs (7) to a clamping device (8), the clamping device (8) being arranged in the area cementless neck (2) of the prostheses and can be removed when the ribs (7) are interrupted.