Bipolar hip prosthesis with locking head

An articulating prosthesis comprising:

• a shell having a spherical outer articulation surface for articulating with an acetabulum and an inner surface, a longitudinal axis, an inferior aperture and a superior apex;
• a liner matable with the inner surface of the shell in proximity to the superior apex of the shell and having a spherical inner articulation surface for articulating with a prosthetic femoral head;
• and
• a locking liner element disposed within the shell and matable with the inner surface of the shell in proximity to the inferior aperture, the locking liner element including at least one resilient locking element integral therewith and extending from a region proximate to the inferior aperture of the shell inward toward the longitudinal axis of the shell and at least partially in a superior direction toward the apex of the shell, the resilient locking element is deformable, in response to an insertion force directed from the inferior aperture, from a first position, defining a first nominal diameter, outward away from the longitudinal axis of the shell to define a second, larger diameter and returns to its first position upon removal of the insertion force, the locking liner element further comprising a groove formed in the locking liner element, adjacent to a superior surface of the at least one resilient locking element the groove providing clearance for the resilient locking element to deform in response to an insertion force directed from the inferior aperture;
• and
• a stem member having a spherical head adapted to fit within and to articulate with the spherical inner surface of the liner;
• wherein the locking liner element has a superior surface that abuts an inferior surface of the liner and the locking liner element includes an inferior facing surface that abuts a superior facing surface formed in the inner surface of the shell to hold the locking liner element against inferior movement with respect to the shell;
• and
• wherein the spherical head is sized so as to deform the locking element from its first position to its second position in response to an insertion force applied to the spherical head from an inferior direction, allowing the spherical head to pass through the second, larger diameter of the locking element and to articulatably engage the spherical inner surface of the liner, the spherical head further being sized so as to allow the resilient locking element to return to its first, nominal diameter after the spherical head has engaged the inner surface of the liner.