“…To describe the 3D, dynamic motion of a joint, 3D motion trajectories of adjacent bones are required and can be obtained by best-matching the bone geometry to the corresponding successive two-dimensional (2D) images provided by the imaging systems. To this purpose, a number of 3D/2D image registration algorithms were proposed (Flood and Banks, 2018;Haque et al, 2012;Akbari-Shandiz et al, 2018;Markelj et al, 2012;Postolka et al, 2020;Lin et al, 2020;Lin et al, 2013), in which the subject-specific bone geometry were obtained either using computed tomography (CT) (You et al, 2001;Tsai et al, 2010;Postolka et al, 2020;Pitcairn et al, 2018), magnetic resonance (MR) imaging (Moro-Oka et al, 2007; Van de Velde and Bingham, 2008;Moewis et al, 2012) or statistical shape models (Tsai et al, 2015).…”