Abstract: A medical procedure includes providing a prosthesis which includes (i) a body portion having a rear surface and a bearing surface, and (ii) an anchor peg including a shaft extending from the rear surface of the body portion, wherein the anchor peg includes a plurality of outwardly extending fins secured to the shaft, and further wherein the plurality of outwardly extending fins each possesses a first diameter. The medical procedure further includes creating an anchor hole in a natural bone, the anchor hole possessing a second diameter which is less than the first diameter. In addition, the method procedure includes positioning the anchor peg within the anchor hole so that each of the plurality of outwardly extending fins deforms so as to possess (i) a concave side which faces an open end of the anchor hole, and (ii) a convex side that faces a closed end of the anchor hole.