First carpometacarpal and interphalangeal osteoarthritis of the hand in patients with advanced hip or knee OA. Are there differences in the aetiology?

Differences in the aetiology of osteoarthritis (OA) of the first carpometacarpal joints (CMC-1) and the interphalangeal joints (IP) have been reported. It was the purpose of this investigation to evaluate whether isolated OA of the first carpometacarpal joints and the interphalangeal joints differs in its aetiology, considering potential risk factors such as age, gender, body mass index, occupational history, OA in the hip or knee joints, hypertension and diabetes in patients with advanced hip or knee OA. Included in this investigation were 639 patients scheduled for either hip or knee replacement because of advanced OA. As well as a standardised interview and clinical examination, bilateral radiographs of both hands were obtained. According to the presence or absence of radiographic OA, participants were categorised as having CMC-1 OA (= 1 joint) or IP OA (= 2 joints), either isolated or in combination. Odds ratios (OR) and their 95% confidence intervals (CI) for potential determinants of OA were estimated using multivariable logistic regression. Of the total number of patients, 184 had CMC-1 OA and 424 IP OA. Patients with CMC-1 OA were more likely to be female (77.2%), and to have knee OA (62.5%) and hypertension (63.0%), than patients without CMC-1 OA. No differences between CMC-1 OA and IP OA were observed for the role of age, body mass index and diabetes. Age was associated with both CMC and IP OA. Female gender was independently associated with CMC-1 OA (OR=1.79; 95% CI: 1.16-2.74) but not with IP OA. Our data suggest a possible impact of age and female gender on the aetiology of CMC-1 OA and of age on IP-OA, at least in patients with advanced hip or knee OA.