Osteoarthritis is the most common degenerative joint disease, causing pain and immobilization and creating a huge economic burden. Traditionally osteoarthritis has been thought to be a disease of articular cartilage, but it is currently accepted to be a disease of the whole joint. Various osteoarthritis-related modifications have been identified in both subchondral bone and calcified cartilage. Furthermore, the subchondral bone is an attractive target for pharmacological treatments due to its high metabolic activity and remodeling. However, the osteoarthritis-derived alterations in subchondral bone and calcified cartilage (especially those concomitant with articular cartilage) and specifically the role of these changes in initiation and progression of osteoarthritis remain elusive. Understanding the concomitant and independent alterations in articular cartilage, calcified cartilage, and subchondral bone, together with the crosstalk between these tissues in osteoarthritis, may be the key towards novel inhibitive or progress preventative treatments of osteoarthritis.

In this special issue, the fundamental modifications of subchondral bone in osteoarthritis will be discussed through original research articles and comprehensive review articles.

Submissions that further the understanding of changes that occur during osteoarthritis, such as morphological, compositional, vascular, and mechanical (micro- and nanoscale) changes, including computational modeling techniques, are welcomed. A demonstration of conceptual understanding of the crosstalk between subchondral bone and the articular cartilage, supported by a combination of analysis techniques, is especially welcomed. Furthermore, in vivo and in vitro studies on subchondral bone-targeted drug treatments as well as mechanisms and crosstalk between subchondral bone and articular cartilage are encouraged.

Potential topics include but are not limited to the following:

• Osteoarthritis-related alterations in subchondral bone
• Concomitant and independent modifications in subchondral bone, calcified cartilage, and articular cartilage during osteoarthritis
• Crosstalk between tissues in osteochondral junction during osteoarthritis
• Animal models of osteoarthritis and preclinical studies on osteoarthritis treatment
• Development of tools for analysis of osteoarthritic alterations in subchondral bone, calcified cartilage, and articular cartilage