A prosthesis suited for orthopedic implantation comprising a modular intramedullary rod that provides intramedullary guidance and that supports an artificial joint surface that can articulate with another artificial joint surface in various ways. Intramedullary guidance systems and methods introduce some and/or all surgical tools and ankle prostheses components through the tibia, using minimal invasive exposure. The systems and methods align the talus and tibia for the installation of one or more ankle prostheses components, and also maintain that alignment during the installation using intramedullary guidance.