The book elucidates the nature of the most common form of arthritis in humans. If osteoarthritis is certain, it is extremely important to facilitate its diagnosis, prevention, indications and options for treatment. Development in comprehending this disease has taken place with recognition that it is not simply a degenerative joint disease. Causative factors, like ligamentous abnormalities, malalignment, overuse, and biomechanical and metabolic factors have been identified as responsible for intervention. The diagnosis of this disease is based on recognition of overdevelopment of bone at joint margins. This contrasts with overdevelopment of bone at vertebral margins, which is not a symptomatic phenomenon and has been renamed spondylosis deformans. Osteoarthritis is described as an abnormality of joints, but the severity does not certainly produce pain. Therefore, the sections include overview of osteoporosis, imaging, biomechanics and genetics.