PTH and osteoarthritis: The studies on PTH effect on osteoarthritic subchondral bone showed iPTH administration resulted in improvement of subchondral bone structure (Bellido et al., 2011; Yan et al., 2014; Dai et al., 2016; Orth et al., 2013) or contradict result of induction of osteoarthritis (Orth et al., 2014).