A knee replacement prosthesis includes a distal femoral implant, including a femoral head portion, including an outer arcuate surface, and interior posterior surface, an interior distal surface disposed at a first angle with respect to the interior posterior surface, and a first interior intermediate surface joining the interior posterior surface and the interior distal surface and being disposed at a second angle with respect to the interior posterior surface and at a third angle with respect to the interior distal surface. The distal femoral implant includes stackable femoral spacers secured to at least one of the interior posterior surface and the interior distal surface, thereby adjusting an aggregate spacing between the interior posterior surface and/or the interior distal surface and a resected surface of a distal femur of the patient. A tibial implant is also provided. Related methods of use of either implant or both are also provided.