[Shoulder prostheses].

The design of shoulder prostheses has been developed through four generations which mirror adaptation to our increasing knowledge of the biomechanics of the shoulder joint. Modern shoulder prostheses are adapted to the size, inclination, posterior offset, and retrotorsion of the shoulder. The main reasons for implantation of a shoulder prosthesis are primary osteoarthritis, posttraumatic and rheumatoid arthritis, avascular necrosis, instability arthritis and cuff defect arthropathy. Typical implants are cup prostheses for surface replacement, anatomical stem prostheses, and reverse prostheses. Total prostheses are functionally better as soon as the arthritis involves the glenoid, whereas hemiprostheses should be preferred as long as the glenoid is intact. The stem is mostly cemented, whereas in younger patients with good bone quality a cementless stem may be used. Cemented glenoids may be considered as standard.