A shaft system for a leg prosthesis with the shaft system featuring a prosthesis shaft which has a wall made of fiber-reinforced plastic material and which features at its proximal end an entrance opening and at its distal end a fastening assembly for the connection of prosthesis components and the attachment of tensioning elements and functional parts of the prosthesis such as locks, draw-in and connecting elements. In order to enable on such a shaft system the feasibility and faster adaptability to the requirements of a user of this shaft system, it is proposed to provide the aforementioned passage opening with at least one reinforcement element. This allows easier fitting of a prosthesis because of the possibility of a faster and simpler repositioning if needed or the faster exchange of prosthesis components.
