The Osteochondral Unit

To accomplish joint preservation, the osteochondral unit, which comprises articular cartilage and underlying subchondral bone, should be understood and treated accordingly. Articular cartilage plays a role in both smooth joint movement and weight-bearing capabilities, while subchondral bone supports the articular cartilage to maintain its homeostasis. Cartilage and subchondral bone interact (through crosstalk) within the osteochondral unit and cooperate to perform joint function. Therefore, it is appropriate to target articular cartilage and subchondral bone in the task of restoring joint function. The strategies for joint preservation aim to prevent the development of osteoarthritis (OA) and to treat joints which have already developed OA, by preserving or restoring joint function. Surgical procedures should be chosen based on which specific area of the osteochondral unit needs to treatment, such as the cartilage layer, subchondral bone, or both. The important thing to keep in mind is the concept of repairing the whole osteochondral unit, the purpose of which is to restore the function of the osteochondral unit for joint preservation.