Abstract: A modular knee finishing block comprising a rigid molded finishing block having an upper and a lower surface and a posterior surface extending between the upper and lower surface, and a tapered surface extending between the upper and lower surface between opposed edges of the posterior surface, and having a knee bracket casting receiving cavity formed in the finishing block and opening into the lower surface and the posterior surface. The receiving cavity has a receiving surface with a plurality of attachment members opening into the receiving surface and each including a passage between the receiving surface and the upper surface. A pair of posterior flexion clearance grooves extend from the receiving surface to the posterior surface. A finishing plug is shaped to conform to the receiving cavity and have a lip sealingly engaging the bottom surface adjacent the receiving cavity, and to conform to the shape of the grooves.