Influence of health system and patient characteristics on expectations and outcome in total hip arthroplasty patients in the Dutch-German border region: protocol for a mixed-methods prospective observational comparative study (hip across)

IntroductionTotal hip arthroplasty (THA) is the treatment of choice for end-stage osteoarthritis of the hip. Management of THA differs between countries, and it is hypothesised that this can influence patients’ expectations and self-efficacy. Using Chen’s intervening mechanism evaluation approach, this study aims to explore how structure of care influences expectations and self-efficacy of patients undergoing THA, and how expectations and self-efficacy in turn influence outcome in terms of perceived physical function and satisfaction.Methods and analysisA mixed-methods study will be conducted in two German and two Dutch hospitals near the Dutch-German border. In the quantitative part, patients will complete questionnaires at three timepoints: preoperatively and at 3 and 6 months postoperatively. Data analysis will include multiple regression analysis and structural equation modelling. In the qualitative part, interviews will be held with patients (preoperatively and 3 months postoperatively) and healthcare providers. Analysis will be performed using structured qualitative content analysis.Ethics and disseminationThe study is approved by the Institutional Review Boards of both Carl von Ossietzky University Oldenburg (2021–167) and University Medical Center Groningen (METc 2021/562 and METc 2021/601). The results will be disseminated in the international scientific community via publications and conference presentations.Trial registration numberThe study is registered in the German Clinical Trials Registry (DRKS: DRKS00026744).