When someone's knee hurts with every step it's a sign that the cartilage has been so badly damaged that the bones rub together when walking.
Medical scientists are developing a technique to produce cartilage tissue artificially so that patients with such knee problems can walk free of pain again. The aim is also to make tendons and blood vessels in the laboratory. The research scientists place cells on a porous scaffold material, for example a non-woven made of polymer fibers. The cells can then grow on this frame and form tissue. Whether the cells will grow properly into tissue, however, depends on many factors. For instance, the cells only form cartilage if they are subjected to loads comparable with those in the body. To form cartilage the tissue needs to experience the pressure applied by every step. By contrast, blood vessel tissue needs the pulsation of the blood. The scientists reproduce these loads in the cell culture. When the artificial cartilage is inserted in the patient's knee the supporting scaffold is gradually resorbed and only the cartilage tissue remains.