Decreased quantity and quality of the periarticular and nonperiarticular bone in patients with rheumatoid arthritis: a cross-sectional HR-pQCT study

Rheumatoid arthritis (RA) is a highly bone destructive disease. Although it is well established that RA leads to bone loss and increased fracture risk, current knowledge on the microstructural changes of bone in RA is still limited. The purpose of this study was to assess the microstructure of periarticular and nonperiarticular bone in female and male RA patients and compare it with respective healthy controls. We performed two high-resolution peripheral quantitative computed tomography (HR-pQCT; Xtreme-CT) scans, one of the distal radius and one of the ultradistal radius in 90 patients with RA (60 females, 30 males) and 70 healthy controls (40 females, 30 males) matched for sex, age, and body mass index. Volumetric bone mineral density (vBMD), bone geometry, and bone microstructure including trabecular bone volume fraction (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), cortical thickness (Ct.Th) and cortical porosity (Ct.Po) were assessed. At the distal and ultradistal radius, trabecular (p=0.005 and p<0.001) and cortical BMD (p<0.001 and p<0.001) were significantly decreased in male and female patients with RA, respectively. BV/TV was also decreased at both sites, based on lower Tb.N in female RA (p<0.001 for both sites) and lower Tb.Th (p=0.034 and p=0.005) in male RA patients compared with respective healthy controls. Cortical thinning (p=0.018 and p=0.002) but not Ct.Po (p=0.070 and p=0.275) was pronounced in male and female RA patients at the distal radius. Cortical perimeter was increased in male and female RA patients at both sites. Multiple regression models showed that bone geometry (cortical perimeter) is predominantly influenced by age of the RA patient, cortical thickness by both age and disease duration, and trabecular microstructure predominantly by the disease duration. In summary, these data show profound deterioration of bone microstructure in the appendicular skeleton of RA patients at both periarticular and nonperiarticular sites.