Causes
Osteoarthritis occurs when the cartilage that cushions the ends of bones in your joints gradually deteriorates. Cartilage is a firm, slippery tissue that permits nearly frictionless joint motion.
In osteoarthritis, the slick surface of the cartilage becomes rough. Eventually, if the cartilage wears down completely, you may be left with bone rubbing on bone.
Risk Factors
Factors that may increase your risk of osteoarthritis include:
Older age. The risk of osteoarthritis increases with age.
Sex. Women are more likely to develop osteoarthritis, though it isn't clear why.
Obesity. Carrying extra body weight contributes to osteoarthritis in several ways, and the more you weigh, the greater your risk. Increased weight puts added stress on weight-bearing joints, such as your hips and knees. In addition, fat tissue produces proteins that may cause harmful inflammation in and around your joints.
Joint injuries. Injuries, such as those that occur when playing sports or from an accident, may increase the risk of osteoarthritis. Even injuries that occurred many years ago and seemingly healed can increase your risk of osteoarthritis.
Certain occupations. If your job includes tasks that place repetitive stress on a particular joint, that joint may eventually develop osteoarthritis.
Genetics. Some people inherit a tendency to develop osteoarthritis.
Bone deformities. Some people are born with malformed joints or defective cartilage, which can increase the risk of osteoarthritis.
Complications
Osteoarthritis is a degenerative disease that worsens over time. Joint pain and stiffness may become severe enough to make daily tasks difficult.
Some people are no longer able to work. When joint pain is this severe, doctors may suggest joint replacement surgery.