Joint space narrowing, cartilage and physical function: are we deceived by measurements and distributions?

摘要

Irreversible physical function loss-that part of physical function loss that remains in the absence of clinically perceptible disease activity-was elegantly conceptualised by Aletaha et at a few years ago. They introduced the idea of the irreversible health assessment questionnaire (HAQ) score, which is the residual HAQ score if a patient is in clinical remission. While one may argue the construct validity of an irreversible HAQ score (eg, the absence of clinical disease activity does not necessarily imply the absence of joint inflammation), the model is valuable because it allows the investigator to disentangle the contribution of signs and symptoms and that of structural damage on physical function.From many studies performed during the past 10 years we have learnt that structural joint damage independently of disease activity contributes to explaining physical function (eg, Welsing et al). Therefore, in the absence of disease activity, it is structural joint damage that explains irreversible physical function loss.