Rheumatoid arthritis (RA) is a chronic autoimmune disease marked by synovial inflammation and joint destruction, resulting in disability and reduced quality of life1. Beyond its articular manifestations, RA is a major cause of secondary osteoporosis2. Patients with RA face a higher risk of osteoporosis and fragility fractures due to factors such as chronic inflammation, reduced mobility, and the use of glucocorticoids3.

Bone erosion, a hallmark of RA, is associated with severe disease activity and progression4. While conventional radiography remains the standard for assessing bone erosion, it lacks sensitivity for early changes and detailed bone microarchitecture5. Dual-energy X-ray absorptiometry (DXA), commonly used to measure bone mineral density (BMD) and diagnose osteoporosis, fails to fully assess bone quality6.

Advances in DXA technology have introduced novel software for three-dimensional (3D) analysis, allowing separate evaluation of trabecular and cortical bone compartments7. This tool elucidates secondary osteoporosis, particularly in patients with RA with predominant cortical bone involvement due to bone erosion8.

Quantitative computed tomography (QCT) has been traditionally used for 3D bone quality assessment but involves higher radiation exposure and limited accessibility compared to DXA9. The 3D-Shaper software, compatible with DXA images, offers a promising alternative for evaluating bone microarchitecture without added radiation or specialized equipment10.

The 3D-Shaper tool offers comprehensive analysis of trabecular and cortical bone compartments, similar to QCT but with lower radiation and greater accessibility11. It measures volumetric BMD, cortical thickness (CTh), and trabecular bone score (TBS), providing a more detailed bone quality assessment than standard DXA10. Moreover, it shows a strong correlation with QCT measurements across populations, including postmenopausal women7.

In RA, where systemic bone loss and localized erosions coexist, the ability to separately assess trabecular and cortical bone is particularly valuable12. The 3D-Shaper tool provides insights into the RA’s differential effects on these bone compartments, potentially revealing bone loss patterns undetectable by conventional DXA or even QCT.

Given the importance of bone quality assessment in patients with RA and the potential advantages of the 3D-Shaper tool over QCT, we conducted a retrospective study to compare 3D bone structure in postmenopausal female patients with RA and without bone erosion. We hypothesized that patients with bone erosion would cause distinct changes in their trabecular and cortical bone compartments compared to those without erosion, providing insights into the pathophysiology of secondary osteoporosis in RA and highlighting the utility of this novel DXA-based 3D analysis.