Why do total shoulder replacements fail?

A well-functioning total shoulder replacement (TSR) relieves pain and utilizes the native soft tissues to recreate the kinematics of the shoulder. A failed TSR can be painful and functionally limiting, and it reduces the patient's quality of life and their ability to perform normal activities of daily living. Total shoulder replacements fail due to a range of factors, including aspects related to the implant, the surgical technique, and patient factors. There has been a rapid rise in the number of implanted TSRs over the last three decades. This is expected to continue to increase, outpacing projections based on population and surgeon density. At 10 years, the survival of TSRs has been reported to be 90%, but estimates beyond 10 years are limited. In the small number of reported cases, there is the suggestion that there may be a significant failure rate in the second decade following implantation. The design of TSRs has evolved rapidly; however, failure of the glenoid component has consistently remained the biggest challenge to improving the survival and functional outcome. The reliance on an adequately functioning rotator cuff signals the importance of understanding each implant's design tolerance and the constraints of the patient's native anatomy. This chapter will outline the current estimations and future projections of TSR failure. This will be followed by a focused discussion on the known individual elements that influence the failure rate, including the implant-, surgery-, and patient-related aspects.