The Relationship between Radial Bone Properties and Disease Activity and Physical Function in Individuals with Rheumatoid Arthritis

PURPOSE: People with rheumatoid arthritis (RA) are at increased risk for osteoporosis. This study explored the relationships between compartment-specific (cortical and trabecular) bone properties in the distal radius, a common site for osteoporotic fracture, and RA-related pain, upper-limb disease activity, and hand function in adults diagnosed within the previous 8 years. METHODS: Cortical and trabecular bone properties (mass, density, and apparent trabecular structure) were assessed at the 4% site of the radius in 21 adults with RA using peripheral quantitative computed tomography (pQCT). Clinical measures included upper-limb active joint count; self-reported pain (AIMS-2 Arthritis Pain scale) and physical function (AIMS-2 Hand and Finger Function scale); and grip strength (modified sphygmomanometer). Associations were characterized using correlations (Pearson correlation coefficients or Spearman's rho). RESULTS: Cortical and trabecular bone mass and trabecular bone density were negatively associated with the number of active joints (r=-0.47, -0.54, and -0.47, respectively). Cortical bone density and mass were associated with grip strength (r=0.61 and 0.51, respectively). Cortical and trabecular bone density and cortical bone mass were negatively associated with scores on the Hand and Finger Function scale (r=-0.49, -0.45 and -0.56, respectively). CONCLUSIONS: Although the patterns differed slightly for cortical and trabecular bone, better bone health in both compartments was associated with fewer active joints and lower self-reported hand disability in adults with RA.