"The intervertebral discs form the elastic part of the spine. It is composed of the annulus fibrosus, a tough outer layer of fibrocartilage, surrounding an elastic gelatinous core, the nucleus pulposus (NP). With age, the water content of the NP decreases, thus, the mechanical loads concentrate on the annulus. This leads to the NP wear, and cracking with a subsequent inflammation reaction and a pr ...