Osteoarthrosis is the loss of articular cartilage associated with a proliferative response in and around the joint. At the cellular level, the process is characterized by both anabolic and catabolic responses. Osteoarthrosis is most prevalent in North America and Europe where, not counting proximal interphalangeal involvement, which can be caused by many factors other than osteoarthrosis, the hip is the most affected joint, followed by the knee. Slowly applied loads cause the deformation of viscoelastic materials, such as subchondral bone and articular cartilage. Squeezed in this fashion, articular cartilage and cancellous bone compress, the cartilage more than the bone. Joints made incongruous by hereditary, developmental, traumatic, or infectious causes can go on to osteoarthrosis. The deleterious effects of repetitive impulsive loading may explain idiopathic osteoarthrosis as well, which we believe occurs in otherwise normal joints devoid of preexisting incongruity or other damage, in individuals who are unable to protect themselves against repetitive impulsive loading.