Alterations in Small Non-coding MicroRNAs (miRNAs) and the Potential Role in the Development of Aseptic Loosening After Total Hip Replacement: Study Protocol for an Observational, Cross-Sectional Study

Introduction: Total hip arthroplasty (THA) is one of the most successful and effective surgeries for the treatment of hip osteoarthritis, with good rates in terms of survival, pain relief, and patient functional recovery. Aseptic loosening (AL) accompanied by periprosthetic osteolysis (PPOL) is the most frequent late complication, accounting for almost 50% of all revision surgeries. The primary purpose of this observational, cross-sectional study is to identify alterations in small, non-coding RNAs, miRNAs, that could be involved in the pathogenesis of AL and PPOL following THA. Methods/design: Sixty-three patients will be included in this study and will be divided into three groups (21 in each group): Group A (control group), including patients undergoing primary THA due to degenerative hip osteoarthritis, Group B including patients without clinical and radiological evidence of PPOL/AL following primary THA, and Group C including patients with clinical and radiological evidence of PPOL and AL undergoing revision surgery following primary THA. Blood samples will be collected from all patients. Peripheral blood samples from Group A and C patients will be collected prior to surgery while synovial membrane samples will also be collected intraoperatively. Synovial membrane samples will not be collected from Group B patients since they are not candidates for any surgical intervention. The relative expression of miRNAs let-7i-5p, let-7e-5p, miR-15a-5p, miR-30a-3p, and miR-130a-3p, will be measured using real-time quantitative PCR (qRT-PCR) at baseline from all patients. Conclusion: The primary goal is to identify the expression of inflammation-related miRNAs that could play a role in the pathophysiology of AL and highlight the differences among patients with confirmed AL, patients with degenerative hip disease, and patients with no signs of AL following THA. The secondary goal is to use these miRNAs as biomarkers to estimate the possibility for a patient to develop AL after total hip replacement, and also as possible treatment targets. Our study has been registered with an International Standard Randomized Controlled Trial Number ID: ISRCTN25839413.