Where Two Common Conditions of Aging Meet: Osteoarthritis and Sarcopenia.

Osteoarthritis and sarcopenia are the most frequently described musculoskeletal disorders in older persons but the intertwining of these conditions and of their functional and cellular causes is complex. This narrative review aims to identify the links between osteoarthritis and sarcopenia described 1-in clinical studies, 2-in in vitro studies, and 3-the available treatment strategies for both conditions. Electronic databases were used for the literature search of all studies investigating the relationship between sarcopenia and the presence of concomitant osteoarthritis. This review identified a limited number of clinical and morphometric studies on the complex relationship between osteoarthritis and sarcopenia. Studies present a number of methodological limitations due to definition and assessment of both entities. Low lean mass is one of the main actors of this cross-talk between muscle and bone, and adipose tissue plays a major role that had been underestimated. Bone Morphogenetic Proteins and myostatin pathways are key mediators and play an important role in both muscle and bone homeostasis. Common therapeutic recommendations are still missing. There is a need for good quality prospective studies on concomitant sarcopenia and osteoarthritis, more translational research, and pharmacological and non-pharmacological therapies in order to identify common denominators for the management of sarcopenia, osteoarthritis, and their comorbidities.