From the bone edge field of the stem null femur for the cement less die

摘要

PROBLEM TO BE SOLVED: To make the concavities and convexes formed on the surface of a stem resistible to the shearing force acting on the interface in the axial and rotational directions for enhancing the stem's initial fixation strength and also improving easiness to draw out the stem in another operation.;SOLUTION: Projections 11 are formed over the surface of a stem 1 to prevent the stem from sinking down or lateral turning within a punched hole 4 of the artificial hip joint. On the diaphysis region 7's side of the projection, there is a pressing part 15 with a seating face 17 that pushes a spongy bone 3 existing at the inner wall of the punched hole toward the diaphysis region 7 for preventing the sink-down of the stem 1 toward the diaphysis region. When an inclined ridge line 23 connecting the pressing part end to the point on the base face 22 of projection 11 located closest to an epiphysis region 6 is formed to thrust the projection side face 24 including the ridge line as its side into the spongy bone 3, the projection side forms a resistant face 16 to control the rotational movements of the stem.;COPYRIGHT: (C)2010,JPO&INPIT