To compare levels of grip strength in individuals with hand osteoarthritis (OA) with normative values, and to examine how hand OA severity and other biopsychosocial factors are associated with grip strength.
Levels of grip strength across age groups were compared with normative values from the general population in sex-stratified analyses using 2-sample t-tests. Associations between radiographic hand OA severity (Kellgren/Lawrence sum score) in different joint groups and grip strength of the same hand were examined in 300 individuals from the Nor-Hand study using linear regression. Analyses were repeated using markers of pain, demographic factors, comorbidities, and psychological and social factors as independent variables. We adjusted for age, sex, and body mass index.
Individuals with hand OA had lower grip strength than the general population, especially in individuals age <60 years. In thumb base joints, increasing radiographic severity (range 0-8) and the presence of pain were associated with lower grip strength (β = -0.83 [95% confidence interval (95% CI) -1.12, -0.53] and β = -2.15 [95% CI -3.15, -1.16], respectively). Negative associations with grip strength were also found for women, low education, higher comorbidity index, and higher resting heart rate.
Individuals with hand OA have lower grip strength than the general population. Our results support the idea that studies on thumb base OA should include grip strength as an outcome measure. However, other biopsychosocial factors should also be considered when the grip strength is being interpreted, because other factors such as sex, socioeconomic factors, physical fitness, and comorbidities are negatively associated with grip strength.