Osteoarthritis is essentially joint failure because all structures of the joint undergo pathologic changes. Traditionally, OA was considered to be a disease of articular cartilage, with loss of cartilage considered to be the essential pathologic process for OA. In recent years, however, it has been realized that OA affects the entire joint structure, including the synovial lining, ligaments, supporting subchondral bone, along with the articular cartilage. Each structure in the joint plays a unique and important in the daily function of the joint. Articular cartilage, with its compressive stiffness and smooth surface; synovial fluid, which provides a smooth and frictionless surface for movement; the joint capsule and ligaments, which protect the joint from excessive excursions; the periarticular muscles, which minimize focal stresses across the joint by appropriate muscle contractions; the sensory fibers, which provide feedback for muscles and tendons; and the bone supporting the cartilage (subchondral bone), with its mechanical strength and shock-absorbing function all interact in an intricate manner to provide optimal function for the joint. Destruction of any of these structures or a disruption in the balance between them leads to the process of arthritis.
A discussion of each risk factor is beyond the scope of this Blog but they may be divided into systemic categories (advancing age, gender, genetics) and local categories (anatomy, trauma, body mass, repetitive use injury, bone density). In considering the clinical features, there is no correlation between the X-ray and the degree of pain. The most likely sources of pain in OA are synovial inflammation, joint effusion, and bone marrow edema. All is dependent on and mediated by a loss of balance in the cartilage cell (chondrocyte) mediated balance between growth factors, cytokines and enzymes that breakdown the cartilage. OA becomes an inflammatory process initiated and propagated by inflammatory mediators that lead to the demise of the articular cartilage first and damage to other structures over time.
How might stem cells change the natural history of Osteoarthritis progression? The stem cells are chondrogenic when introduced into the proper environment. Even if they do not give rise to chondrocytes that are responsible for manufacturing collagen type 2 and aggracan; The Bone Marrow Aspirate derived Stem Cells when concentrated and introduced into the arthitic joint produce the cytokines and growth factors to control the breakdown of extracellular matrix by Interleukin 1-B and tumor necrosis factor-a. Difficult to understand? Call, make an appointment, I will explain and then you decide about a stem cell intervention rather than a Total Joint Replacement.