Implant Retrieval

Abstract

Retrieval analysis is an important aspect of medical device development. Examination of retrieved devices allows device developers to close the design loop, understand the performance of devices, and validate assumptions made and methods used during preclinical testing. In this chapter, we provide an overview of the implant retrieval analysis performed at the Implant Research Center at Drexel University on reverse total shoulder systems retrieved after short- to medium-term implantation. Our evaluations include assessment of the polyethylene bearing surface, glenosphere bearing surface damage, and tribocorrosion at the modular junctions. We have observed that polyethylene bearing surface wear (mode I) is limited in the short to medium term and that wear and damage of revised devices are dominated by unintentional contact and impingement of the inferior rim of the bushing (mode II damage). Scratching and damage of the glenosphere was a common observation, particularly in patients with a history of instability. Damage at the modular junctions was limited and dominated by fretting rather than corrosive damage. These observations provide an increased understanding of device performance and potential failure modes. Further studies will be necessary to characterize the long-term performance of reverse total shoulder systems.