High hand joint mobility is associated with radiological CMC1 osteoarthritis: the AGES-Reykjavik study

Previous studies have indicated that joint hypermobility may affect the development of clinical and radiological hand osteoarthritis (OA), but this question has not been addressed in epidemiological studies. Our objective was to investigate this relationship in a population-based study.

The study group consisted of 384 unselected older participants in the Age, Gene/Environment Susceptibility-Reykjavik Study (161 males, median age 76, range 69-90, and 223 females median age 75, range 69-92). The criterion used for joint mobility was the single maximal degree of hyperextension of digits 2 and 5 on both hands (HYP degrees).

HYP degrees was more prevalent in females and on the left hand in both men and women. Both genders had a positive association between the degree of mobility measured by HYP degrees and radiological scores for the first carpometacarpal joint (CMC1) OA. Thus, those with HYP degrees >or=70 had an odds ratio of 3.05 (1.69-5.5, P<0.001) of having a Kellgren-Lawrence score of >or=3 in a CMC1 joint. There was also a trend towards a negative association between HYP degrees and proximal interphalangeal joint scores.

Hand joint mobility, defined as hyperextension in the metacarpophalangeal joints (HYP degrees ) is more prevalent in females and on the left side. It was associated with more severe radiographic OA in the CMC1 joints in this population. The reasons for this relationship are not known, but likely explanations involve ligament laxity and CMC1 joint stability. These findings may relate to the left-sided predominance of radiographic OA in the CMC1 joints observed in many prevalence studies.