Importance

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Abstract

The invention relates to a ceramic hip joint prosthesis head for use with a trunnion, the trunnion having a frustoconical end comprising a first section having a diameter of about 12 mm which expands inward at a total angle of about 6 degrees to form a second section having a diameter of about 14 mm, wherein each head comprises: a) a substantially spherical outer diameter of about 22.22 mm, b) a centerpoint, and c) a recess which forms a taper wall extending inward from the outer diameter of the head, wherein the taper wall has a shape suitable for taper fitting upon the frustoconical end of the trunnion to produce contact between the taper wall and the first section of the frustoconical end of the trunnion, a perimeter being defined by the deepest contact between the taper wall and the first section of the frustoconical end of the trunnion, the perimeter having a centerpoint,and wherein each head, when taper fit upon the frustoconical end of the trunnion, has a rupture load of at least 46 kN and is characterized by a distance D between a) the centerpoint of the head and b) the centerpoint of the perimeter defined by the deepest contact between the taper wall and the first section of the frustoconical end of the trunnion first section of the frustoconical end of the trunnion, wherein D has an absolute value of less than 3 mm.

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First Claim