- Two Part Articular Segment Displacement:
    - fracture plane is through the anatomic (not surgical neck);
    - anatomic neck represents the old eiphyseal plate;
    - surgical neck represents the weakened area below the tuberosities and head approximately 2 cm distal to the anatomic neck;
    - significant chondral defects and minimally separated fragments may go unappreciated on plain films;
    - through no soft tissue remains attached to the humeral head, the undisturbed blood supply transmitted through the tuberosities may prevent osteonecrosis of the articular segment;

- Treament:
    - ORIF vs. prosthetic arthroplasty;
    - in young active pts, consider screws from the shaft into head may be inserted thru an anterior approach;
    - it may prove difficult to obtain adequate screw purchase in the head fragment without violating the articular surface;
    - prosthetic hemiarthroplasty may be indicated in older pts;
         - deltopectoral approach with release of the subscapularis tendon from lesser tuberosity affords excellent exposure;
         - following removal of the head fragment and reaining of the shaft, the humeral component is implanted in 30 to 40 deg of retroversion relative the epicondyles of the elbow