Is the exposure to bisphosphonates or osteoporosis the predictor of spinal radiographic progression in ankylosing spondylitis? - Giovanni Orsolini; Giovanni Adami; Maurizio Rossini; Angelo Fassio; Alessandro Giollo; Cristian Caimmi; Luca Idolazzi; Davide Gatti; Ombretta Viapiana (Arthritis Research & Therapy, 2018)