Background/Purpose: Rheumatoid arthritis (RA) patients are at higher risk of having generalized osteoporosis of the axial and appendicular skeleton assessed by dual-energy x-ray absorptiometry (DXA) but are also known to have local periarticular bone loss on hand radiographs as a typical manifestation of disease. DXA is the most common method to assess general bone mineral density (BMD) and is recommended for osteoporosis screening in RA patients, while hand radiographs are routinely obtained for RA diagnosis and monitoring. It is unknown if radius cortical bone thickness (CBT) by radiograph correlates with bone mineral density at the radius by DXA in RA patients. The aim of this study is to assess the correlation of distal radius cortical bone thickness (CBT) measurements by routine hand radiographs with DXA BMD and T-score results for osteoporosis screening in RA patients.

Methods: For this Institutional Review board approved retrospective study, RA patients who underwent a distal radius DXA scan and had a hand radiograph taken within a 5-year period were included. Distal radius CBT was ascertained by measuring the outside diameter and the inside diameter of the cortical shell at the metaphyseal/diaphyseal junction and their ratio was calculated (Figure 1). Correlation between CBT of the distal radius and the DXA bone mineral density (BMD) values and T-scores of the distal radius, spine, and femurs were analyzed using Pearson correlation coefficient. Subgroup analyses of the correlation of distal radius CBT with the overall distal radius, ultra-distal radius (UD), mid-distal radius (MD), and one-third distal radius (OT) BMD and T-scores were also performed.

Results: 27 total patients were included for this study (mean age 63.9 years, 81% women). There was moderate positive correlation (p ≤ 0.05) between the distal radius CBT and the MD (r = 0.44), OT (r = 0.38), and overall distal radius BMD (r=0.41). Weak correlation was seen between the distal radius cortical thickness and the overall, UD, MD, and OT T-scores and the ultra-distal BMD without statistical significance. No significant correlation was seen between the distal radius CBT and the T-scores and BMD of the femurs or lumbar spine.

Conclusion: Opportunistic use of routine hand radiographs to measure the distal radius CBT can provide modest correlation to the BMD at the MD, OT, and overall distal radius in RA patients. Larger study population and prospective study could provide confirmation of this correlation.

Distal Radius Cortical Bone Thickness Measurement

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/correlation-between-bone-mineral-density-by-dual-energy-x-ray-absorptiometry-at-the-radius-and-radius-cortical-bone-thickness-using-routine-hand-radiographs-in-rheumatoid-arthritis-patients/