A new prosthetic design for proximal humeral fractures: reconstructing the glenohumeral unit.

A new shoulder prosthesis design for proximal humeral fractures has been developed. The rim of the articular component of this prosthesis has several holes to which the bone-tendon junction of the rotator cuff is fixed, to allow an anatomic reconstruction of the glenohumeral unit. The strength of the tuberosity fixation to this prosthesis is investigated in a cadaveric study. Artificial 4-part fractures were created in 18 human, fresh-frozen, paired shoulder joints with intact rotator cuffs. Two methods of tuberosity fixation were used in a matched-pair fashion. In group I the tuberosities were sutured to the rim of the prosthetic head, and in group II the tuberosities were circumferentially tension band-wired. Strength testing was performed on a material-testing machine, and displacement was recorded with an opto-electronic device. Both fixation methods proved to be equally reliable in the forces exerted during activities of daily living without significant displacement of the fracture fragments.