A femoral component for a prosthetic knee joint has a medial and a lateral condylar portion each having a bearing surface and a bone contacting surface. The medial and lateral condylar portions defining an opening therebetween. The opening is at least partially open to a cavity surrounded by a wall extending proximally from the bone contacting surface of the medial and lateral condylar portions. The wall having an inner surface defining a perimeter of the cavity and medially, laterally and posteriorly facing outer surface portions. The medially laterally and posteriorly facing surface portions being arcuate in shape.
