Abstract: A prosthesis comprising a proximal portion (1) which is shaped to fit within the medullary canal of the metaphysis of the bone and a distal portion (2) shaped to fit within the medullary canal of the diaphysis of the bone. The proximal and distal portions (1,2) are separately formed and fit together by means of a shaft (8) on the distal portion (2) which slides within a hole (7) in the proximal portion (1). The two portions (1,2) may thus be independently selected to provide the desired fit within the bone. Movement of the proximal portion (1) on the stem (8) of the distal portion (2) prevents the latter being forced into a wedge fit with the diaphysis when load is applied to the proximal portion (1). Load transfer between the proximal portion (1) and the metaphysis is thus maintained so avoiding bone resorption.