“…In the ACL dog model of OA, Brandt et al [6] reported that, at a later stage of the disease, 54 months after OA induction, there was a marked increase in the volume of subchondral bone with active bone formation. Studies in OA of the knee and the hand reported that the scintigraphic abnormalities correlated with the osteocalcin concentration in the synovial fluid, which is a marker of bone formation, and serum osteopontin, a bone matrix protein, were also elevated [21][22][23]. Gevers and Dequeker also showed elevated serum osteocalcin levels in women with hand OA, and elevated osteocalcin in cortical bone explants [24].…”