Study protocol: Effectiveness of dual-mobility cups compared with uni-polar cups for preventing dislocation after primary total hip arthroplasty in elderly patients — design of a randomized controlled trial nested in the Dutch Arthroplasty Registry. - Van Beers, Loes W A H; Van Der Wal, Bart C H; Van Loon, Tess Glastra; Moojen, Dirk Jan F; Van Wier, Marieke F; Klaassen, Amanda D; Willigenburg, Nienke W; Poolman, Rudolf W (Acta Orthopaedica, 2020)