Osteoarthritis is the most common type of arthritis. It occurs because of thinning of the cartilage cushion of the joint. As a result the bone underneath responds in an attempt to repair the joint. This is why extra bone forms, and why people grow ‘bumps’ for example on their fingers.
The reasons why people get arthritis range from genetics to other diseases to excess body weight. Abnormal mechanical stresses on the joint(s) – for example after an injury to a joint in younger life – can also lead on to osteoarthritis. This is why rapid evaluation and management of sports injuries is very important.
Some people are born with slightly abnormal joint shape that can also predispose them to osteoarthritis.
Osteoarthritis is diagnosed by careful clinical evaluation. X-rays in the early stages are usually normal. MRI scans and newer imaging technologies allow greater insights into changes within joints and can be very useful in early arthritis.