The term megaprosthesis is typically used to describe prostheses that replace substantial portions of a long bone (i.e., proximal, total, and distal femoral replacements (PFR, TFR, and DFR), and proximal tibial replacements (PTR). In non-oncologic cases, these components are reserved for the indication of massive bone loss which may occur due to fracture, infection, or extensive revision. These operations are therefore deemed “limb salvage” procedures, and they portend a higher risk of complications than most primary or revision arthroplasty surgeries. In this chapter, we will discuss the indications for use of megaprostheses, risks of the procedure, surgical techniques and management principles, and expected outcomes. In addition, we will discuss two cases performed by the senior author that highlight the author’s preferred techniques.