Abstract
Hand osteoarthritis is a common condition which may lead to severe pain and disability. However, the pain intensity does not always correlate with the degree of structural changes. The aim of this thesis was therefore to investigate other factors that may contribute to pain and disability in people with hand OA. We explored whether body mass index (BMI) was associated with pain and pain sensitization, and whether pain sensitization was associated with hand and lower extremity function and number of tender and painful joints in the hands and in the rest of the body.
BMI was assessed in almost 300 participants with hand osteoarthritis in the hospital-based Nor-Hand study. Pain and physical function were examined by self-reported questionnaires and clinical examination, and pain sensitization was investigated by clinical tests (pressure pain algometry and temporal summation).
The results showed that people with a higher BMI reported more pain not only in their knees, but also in their hands. This could not be explained by increased mechanical loading since we do not walk on our hands, but it could possibly be explained by the systemic effects of overweight and obesity. The hormone leptin, which is produced by adipose tissue, was partly mediating the effect of a higher BMI on hand pain. Overweight was also associated with greater pain sensitization, and greater pain sensitization was associated with symptoms like worse physical function and more tender and painful joints in the hands and painful joints in the rest of the body.
These results may contribute with important information to future research on management strategies for hand OA pain. Future clinical trials should explore whether prevention and treatment of overweight are possible management strategies. Pain sensitization can possibly explain why some people with hand OA experience pain and functional limitations, despite minimal structural changes.