Objective: To investigate bone changes in the metacarpophalangeal (MCP) joints of anti-citrullinated peptide antibody (ACPA)-positive patients with arthralgia, but not arthritis, compared to healthy controls.
Method: Using a cross-sectional study design, patients were recruited from hospitals and private care rheumatologists, and controls from a test subject website. All subjects underwent medical history interview, clinical examination, and biochemical screening including ACPA. Patients with positive ACPA, arthralgia, and no rheumatic disease were included. Controls without a history or signs of rheumatological disease or positive ACPA were included. A 2.7-cm-long region around the second and third MCP joints was evaluated using high-resolution peripheral quantitative computed tomography with a voxel size of 82 µm.
Results: Twenty-nine ACPA-positive patients and 29 healthy controls were evaluated. Trabecular volumetric bone mineral density and bone volume fraction did not differ between the groups. In addition, the cortical bone was not affected in patients, as we found no difference in average cortical thickness and cortical bone area between the groups. In contrast, the trabeculae were significantly (p < 0.05) thinner in both second and third MCP heads compared with controls, whereas trabecular number and trabecular separation did not differ between the groups. No erosions were demonstrated and the number of non-specific breaks did not differ between the groups.
Conclusion: Trabecular bone changes were observed in ACPA-positive patients with arthralgia compared with healthy controls. The results may reflect inflammatory up-regulated trabecular bone resorption leading to early bone loss before the onset of clinical arthritis.