Abstract Cementless threaded cups are commonly used in total hip arthroplasty. A method to match the elasticity of the cup to that of natural bone is reducing the wall thickness of the implant. Despite good results with this philosophy of implantation, we recently observed 3 cases of implant fractures after the implantation of such thin-walled cups called “Bicon.” We performed a thorough analysis of 1 of these cases including a histological examination and a technical failure analysis (including scanning electron microscopy) to establish the chronology and cause of the failure. Multiple fractures of the thin-walled metal-back cup were determined to be caused by fatigue. We have concluded that due to the specific material and design parameters of this cup, under adverse circumstances such as the lack of primary or secondary osteointegration, there is a risk of failure due to fatigue.