Radiographic thumb osteoarthritis: frequency, patterns and associations with pain and clinical assessment findings in a community-dwelling population

OBJECTIVES The aim of this study was to investigate: (i) the frequency and patterns of radiographic OA (ROA) in the thumb joints; and (ii) associations between thumb ROA and the clinical characteristics of thumb OA in older adults with hand pain or problems. METHODS Participants were 592 community-dwelling older adults with hand pain or hand problems who attended a research clinic. Hand X-rays were taken and 32 joints were scored for the presence of ROA. The occurrence and pattern of ROA in the hand were examined. Univariable and multivariable associations of thumb pain and clinical assessments (nodes, deformity, enlargement, thenar muscle wasting, grind test, Kapandji index, Finkelstein's test and thumb extension) with ROA were investigated. RESULTS The first CMC and thumb IP joints were the hand joints most frequently affected with ROA. The thumb (thumb IP, first MCP, first CMC, trapezioscaphoid) was the most commonly affected joint group (n = 412). Isolated thumb ROA occurred more frequently than in any other isolated joint group. Multivariable analyses showed that older age, thumb pain, thenar muscle wasting and presence of nodes, deformity or enlargement best determined the presence of thumb ROA. CONCLUSION The first CMC and thumb IP joints were frequently affected with ROA. Prevalence estimates of ROA would be underestimated if these were not scored. One-third of the individuals with thumb ROA did not have involvement of the first CMC joint. The presence of thumb ROA was strongly associated with a combination of older age, thumb pain and clinical features of OA.