The diagnosis of thumb base arthritis is made primarily with an X-ray, however the history you give and the clinical findings will give a very good indication of the problem.
Sometimes the clinical findings are not clearly supported by the x-rays if this is the case then further investigation such as ultrasound scan, CT scan or even arthroscopy of the joint may be required.
Once the diagnosis has been made then the treatment options available will depend on the degree of arthritis and the amount of problems that it is causing you.
Activity modification and analgesia. When symptoms are mild or someone is not keen on any treatment simple measures may be sufficient to control the pain and allow better function.
Splints. These may either be custom made thermoplastic splints or a more generic off the shelf splint. A splint reduces the amount of movement at the joint and therefore reduces the irritation and pain from the arthritis. Splints can be very useful as a temporary measure or used just for activities that cause increased pain.
Steroid Injection. A steroid works as a very strong anti-inflammatory, a steroid can be very useful particularly when there is rest pain. If the pain is more mechanical and only comes on when using the hand then a steroid injection is much less likely to give a good benefit.
Surgery. There are several surgical options for thumb base arthritis and the choice will depend on many factors. These include debridement, joint replacement or trapeziectomy.