Extended articular surface resurfacing head

A modular humeral head resurfacing implant comprising:

• a head including:
• an exterior hemispherical articulating surface defining a terminating rim;
• an interior concave surface opposite to the exterior articulating surface;
• and
• a first coupling mechanism proximate to the terminating rim, the first coupling mechanism comprising an annular groove;
• an anchoring stem coupled to the interior concave surface and extending along a stem axis that extends through an axial center of the head;
• a ring lock;
• and
• a modular extended articulation flange axially protruding from only a portion of the terminating rim of the head when fastened thereto and operable to articulate with at least one element of a coracoacromial arch and including:
• a second coupling mechanism configured to cooperate with the first coupling mechanism, the second coupling mechanism comprising an annular ring integral with the articulation flange and an annular recess formed in the annular ring, the second coupling mechanism being attached with said ring lock to the first coupling mechanism, thereby fastening the articulation flange to the head;
• an outer articulating surface that is curved along substantially its entire length and is substantially flush and congruent with the exterior hemispherical articulating surface when the articulation flange is fastened to the head;
• and
• a curved inner surface that is substantially congruent with the interior concave surface of the head when the articulation flange is fastened to the head, wherein the extended articulation flange is located in a lateral region of the head and extends generally parallel to the stem axis;
• wherein the ring lock cooperates with both the annular groove and the annular recess when the articulation flange is fastened to the head.