In a system for transmitting specifications for a customized prosthesis, particularly a surgical implant such as a femur prosthesis, an order is first transmitted comprising clinical data for a patient from a client (12) to a server (10). Diagnostic information for the patient is then transmitted from a diagnosis unit (13) to the server (10). The information is further transmitted to a processing unit (15), which generates inetr alia a prosthesis design draft. The draft is transmitted to the server (10) and on to the client (12). A specification based on the draft is transmitted from the client (12) to the server, and manufacturing parameters based on the specification are transmitted to a manufacturing unit (14) for manufacture of the prosthesis. The invention relates to methods and devices that form part of such a system on the server and client sides. The invention brings increased efficiency, reliability and interactivity to the process of specification and manufacture of customized prostheses.