MedlinePlus cites normal wear and tear on bone joints, viral or bacterial infections, injuries and autoimmune diseases as common causes of arthritis. Osteoarthritis is the most common type, and it is caused by joint wear and tear and advanced age.
The rubbery cartilage found where bones meet diminishes as people age. When it deteriorates to the point where the bones rub together, it is called osteoarthritis. Joint pain and swelling, limited range of motion and stiffness are symptoms of this condition. It can be triggered by hemophilia, blood supply disorders, gout and other types of arthritis such as rheumatoid arthritis. According to Mayo Clinic, rheumatoid arthritis occurs when the body’s immune system attacks the membrane that covers the joints. Risk factors for this type of arthritis include a family history of the disease, being female, obesity, advanced age and prior joint injuries.
The American Academy of Orthopaedic Surgeons estimates that as many as 15 percent of people diagnosed with osteoarthritis actually have post-traumatic arthritis, which can develop after a joint injury. According to the Department of Orthopaedics and Sports Medicine at the University of Washington, most infectious arthritis is caused by bacteria, such as the bacterium gonococcus that causes gonorrhea, but it can also be caused by fungi or viruses. Infectious arthritis is typically not a lifelong illness and is often successfully treated.