*3.2. Retrieval Sample*

The studied retrieval was constituted by a fully Delta ceramic-on-ceramic (CoC) bearing couple. The total hip replacement (THR) components were a DePuy Pinnacle cup 60 mm and a Summit stem size 3 high offset. The 28 mm Delta ceramic head taper had a +8.5 mm neck length offset.

The patient was informed that the data concerning the case would be submitted for publication, and she provided consent.

The patient underwent complex total hip arthroplasty in 2004 (diagnosis: secondary osteoarthritis following developmental dysplasia of the hip). After twelve years of painfree normal function, the patient presented with periprosthetic joint infection (caused by Klebsiella pneumoniae). After failure of debridement/irrigation and two dislocation events (managed with closed reduction), the patient underwent two-stage revision surgery in late 2016. The retrieved Delta 28 mm CoC bearing appeared intact, with titanium metal stripes in the femoral head caused by recurrent dislocation events. Areas with metal transfer were investigated before and after a cleaning procedure to remove the metal, which consisted in a 10 h bath at 60 ◦C with 30% aqueous H2SO4 solution.

The patient was 50 years old at the time of index surgery; The body weight of the patient was 78 kg, and the patient's body mass index (BMI) was 31. The patient was a housewife with a part-time administration job, and she performed no sports activities.
