Decision making in contemporary shoulder arthroplasty.

Clinical experience with humeral implants has evolved over the past decade, along with a better understanding of shoulder anatomy and function. There is no question that surgeons are getting better at restoring normal anatomic relationships than in preceding decades. Whether or not this impacts implant longevity will only be known with time and further follow-up. Even over the short term, it is difficult to ascertain whether new prosthetic designs have improved patient function as well as has been implied by the related biomechanical studies. Most surgeons with experience using old and new systems realize a greater sense of predictability in achieving their surgical goals when using more modern implants. Concerns over the durability of prosthetic systems with multiple moving parts and hand-tightened locking mechanisms have almost been forgotten in shoulder arthroplasty, but time will also reveal their importance. New glenoid designs have been less exciting, the major problem being one of developing appropriate materials. Polyethylene does not behave like normal cartilage, and its wear is constant and unforgiving. Surgeons now better understand how to reconstruct the normal glenoid position and achieve more secure early fixation than in the past, but this does not promise long-term durability and freedom from complications.