cmc oa of the thumb. however, in about 65% of people older than 55 years, radiologic evidence of oa was present without any symptoms. armstrong et al. reported a prevalence of 33% in postmenopausal women, of which one third was symptomatic, compared to 11% in men older than 55 years. this shows cmc oa of the thumb is significantly more prevalent in women, especially in postmenopausal women, compared to men.