1 in 3-4 women over 50 years of age will get osteoarthrtitis (OA) at the base of their thumb. The incidence is less for men, however the symtoms & cause are the same.
OA is a degenerative joint condition which commonly results is pain, sometimes swelling and decreased movement at a joint. It can result from previous trauma to the joint, or due to chemical changes in the joint, which change the joint surface and surrounding tissues over time. Painful OA is particularly common at the base of the thumb.
The joint at the base of the thumb (at the thumb side of the wrist) is called the first carpometacarpal joint (CMCJ). This joint is affected by OA as the joint allows for a complex and wide degree of movements. It is the joint responsible for opposition, where by our thumb pulp (fleshy surface) can face and pinch the finger tip pulps. Because it allows for a great degree of movment, the joint relies on the soft tissues around it to give it stability. However when OA is present, the stability of these structures is often compromised.
Throughout our lives the first CMCJ certainly gets a work out! The joint positions the thumb so we can use it in almost all activities involving our hands. And it also absorbes and transfers pressure associated with the forces involved in pinch. These shearing and loading forces are generally well tolerated. This is because the soft tissues (ligaments, tendons, muscles) aroud the joint stabilise it- that is until they are damaged.
OA effects change on the bone as well as soft tissues around the involved joint. With loosening and deterioration of the capsule and ligaments around the joint- the bones can shift out of alignment. And this is the process of the development of joint deformities in thumb osteoarthritis. There are different patterns of joint deformity which result from imbalances in muscle and ligament strength and the way the bones line up during different activities.
How we can help you, is be assessing the pattern of deformity, seeing which structures are loose and which are tight, and how the bone is shifting during use and sitting at rest. Hand Therapy can help to reposition the joint, and bring balance to the structures which destabilise the thumb. Please call us today so we can help you get the most out of your thumb 08 8339 HAND (8339 4263).
Author Jo Marsh
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