Different types of arthritis affect people at various ages. For example, osteoarthritis is predominantly seen in older age groups. It typically starts around the age of 40 to 45 years. The risk of osteoarthritis could increase depending on prior joint injuries, family history of osteoarthritis, history of being overweight, and many other factors. On the other hand, rheumatoid arthritis can affect any age groups, including children. Your risk of rheumatoid arthritis depends on your family history and many other environmental risk factors.