Case Reports: Fractures of Threaded Cups: Rare Complications of a Well-established Implant

The use of cementless threaded cups in THA is a well-established treatment. Fractures of the cups are rare complications recorded in individual cases with material defects being discussed as the primary cause. We analyzed three cases of fractured cups. Although all three cups were well fixed to existing bone, we observed deficient osseous backing dorsocranially and abrasion particles. There were no signs of femoroacetabular impingement or infection. The cups showed corrosion debris. Scanning electron microscopic investigations showed characteristics of fretting and fretting-related corrosion. We concluded the fractures occurred because of fretting combined with inadequate bony support leading to fatigue of the material and subsequent fracture. Each author certifies that he or she has no commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article. Each author certifies that his or her institution has approved or waived approval for the reporting of these cases and that all investigations were conducted in conformity with ethical principles of research.