Abstract: An implantable prosthesis has a plurality of grooves formed on a surface to promote biological fixation to the surrounding tissue. The grooves are preferably substantially equal in width, depth and spacing. The width of the grooves ranges from 350-535 microns, and the depth ranges from 380-635 microns. The spacing between adjacent grooves is substantially equal to the width and/or depth of the grooves. A preferred embodiment of the prosthesis of the present invention is a femoral stem for a hip joint which has a plurality of grooves, extending generally transversely to a longitudinal axis of the stem, formed on proximal portions of selected surfaces of the stem. Distal portions of the stem surfaces are relatively smooth. The grooves are oriented approximately perpendicularly to a line of force transmitted from the head to the shank of the stem. The grovoes preferably lie in planes which intersect the longitudinal axis of the shank at an angle of approximately 60.degree.-80.degree..