Background Periarticular bone loss is an early sign of bone involvement in rheumatoid arthritis (RA) and a predictor of subsequent radiographic erosion. High-resolution peripheral quantitative computed tomography (HR-pQCT) is a non-invasive 3D imaging technique capable of independent evaluation of cortical and trabecular components and their respective microstructural features.
Objectives To investigate loss of cortical and trabecular volumetric bone mineral density (vBMD) and changes in microstructure at the second metacarpal bone in RA patients in comparison with healthy controls
Methods For this cross-sectional study, images of the second metacarpal bone were obtained using HR-pQCT in a group of 56 middle-aged RA females (age: 48.5±8.1yrs, disease duration: 10.4±7.8yrs) and a group of 56 matched healthy females (age: 49.5±8.1yrs). HR-pQCT data acquisition yielded a series of 110CT slices proximal to the distal articular surface of the metacarpal head, providing measures of vBMD as well as cortical and trabecular microstructure.
Results There were no significant differences between RA patients and controls in age, body height, body weight, menstrual status, and smoking and drinking habit. Cortical area was decreased significantly in RA patients (-21%, p=0.022) with preserved trabecular area (2.6%, p=0.242). RA patients had significantly decreased cortical (-9%, p=0.001) and trabecular vBMD (-11%, p<0.0001), thinner cortices (-23%, p=0.011), decreased trabecular bone volume fraction (-11%, p<0.0001), and thinner trabeculae (-10%, p=0.002). Trabecular number (-1%, p=0.848) and separation (4%, p=0.347) were comparable between the two groups. Decreases in trabecular vBMD and bone volume fraction in RA patients significantly correlated with increased disease activity, as reflected by higher C-reaction protein levels and Disease Activity Score in 28 Joints scores. On the other hand, increased functional disability, as reflected by higher Health Assessment Questionnaire score, significantly correlated with a decrease in cortical area, cortical vBMD and cortical thickness.
Conclusions Periarticular bone loss in RA is both cortical and trabecular in origin and correlates with increased disease activity and severity. Particularly prominent in RA patients was a decrease in both cortical area and cortical thinning reflecting how periarticular cortical bone loss in RA patients occurs at both the periosteal and endocortical bone sites.
References Fouque-Aubert A, Boutroy S, Marotte H, Vilayphiou N, Bacchetta J, Miossec P, Delmas PD, Chapurlat RD. Assessment of hand bone loss in rheumatoid arthritis by high-resolution peripheral quantitative CT. Ann Rheum Dis 2010;69(9):1671-6.
Disclosure of Interest None Declared