• Dietmar Dammerer, Philipp Blum, David Putzer, Andreas Tscholl, Michael C Liebensteiner, and Martin Thaler.
• Department of Orthopaedics and Traumatology, Medical University of Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria.
• Arch Orthop Trauma Surg. 2021 Feb 1; 141 (2): 327-332.

IntroductionThe most common cause of failure in total hip arthroplasty (THA) is aseptic loosening. Uncemented cup migration analysis by means of Einzel-Bild-Roentgen-Analyse (EBRA) has shown to be a good predictive indicator for early implant failure if the cup migrates more than 2 mm within 4 years after surgery. In this study, we performed a migration analysis of an uncemented peripheral self-locking (PSL) press-fit cup after 4 years follow-up.Materials And MethodsWe retrospectively reviewed all patients who received a trident PSL press-fit cup at our department between 2004 and 2017. A total of 636 patients were identified. As inclusion criteria for radiological analysis, a minimum follow-up of 2 years was defined. We reviewed medical histories and performed radiological analysis using EBRA software. EBRA measurements and statistical investigations were performed by two independent investigators.ResultsA total of 149 cups in 146 patients (female 82; male 64) met our inclusion criteria. Mean age at surgery was 65 years (33-89). We found a significant improvement in the WOMAC score pre- to postoperative (p < 0.0001). EBRA migration analysis showed a mean total migration of 0.6 mm (0.0-8.2) over our follow-up period of 4 years. Of the investigated cups, 69.8% showed a migration rate smaller than 2 mm in the investigated follow-up.ConclusionThe acetabular cup used in our study provides low migration at final follow-up. Therefore, a good long-term outcome can be expected for the PSL cup.Trial RegistrationTrial registration number is 20181024-1875 and date of registration is 2018-10-24.

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