For most people the cause of osteoarthritis is unknown, but metabolic, genetic, chemical, and mechanical factors play a role in its development. It is associated with the aging process and is the most common form of arthritis . It may first appear without symptoms between 30 and 40 years of age and is present in almost everyone by the age of 70.
Symptoms appear in middle age.
The cartilage of the affected joint is roughened and becomes worn down. As the disease progresses, the cartilage becomes completely worn down and the bone rubs on bone. Bony spurs usually develop around the joint. Systemic symptoms, sometimes associated with other arthritic conditions, are not associated with osteoarthritis. The joints of the hands and fingers, hips, knees, big toe, cervical and lumbar spine are commonly affected.