The diarthrodial joint is the most common type of joint in the body. Such a joint consists of a synovium-lined cavity containing synovial fluid that separates articulating cartilage-covered bones. Often, such joints are functional for a lifetime, with the synovial fluid-bathed articular cartilage providing surfaces that are low-friction, wear-resistant, and load-bearing. In adults, damaged articular cartilage does not heal effectively after injury, and a common aging-associated malady is osteoarthritis with progressive cartilage deterioration. Successful therapies for large defects utilize grafts with mechanically mature and appropriately contoured articular cartilage and subchondral bone. However, the supply of such grafts is limited. Bioengineering methods offer the possibility of fabricating such biological tissues. The long-term objectives are to grow and maintain joint fragments and whole joints that can be used for bioarthroplasty surgery. We recently developed a variety of technologies that facilitate joint-scale bioengineering. These include the rapid assembly of cartilaginous tissue, the rapid attachment of soft and hard tissues, the shaping of immature tissue, and evaluation of large osteochondral grafts in animal models. Such fabricated living biomaterials facilitate the future arthroplasty treatment of a number of orthopedic maladies, and thereby represent a paradigm shift from the biomaterials used traditionally and the current generation of engineered tissues.
Joint Lubrication and Osteoarthritis
Bathed in synovial fluid, articular cartilage bears load and slides relative to an apposing tissue surface with remarkable low-friction and low-wear properties. However, in aging and osteoarthritis, the articular surface becomes roughened and eroded. Such deterioration may result from a biomechanical deficiency in synovial fluid after acute injury and during aging and osteoarthritis. This project seeks to contribute to the understanding of the biological and biochemical basis for this, as well as to develop therapeutic strategies. The results may ultimately facilitate diagnostic analysis and therapeutic manipulation of deficient fluid in susceptible joints.