Bone strength is significantly reduced among men and women with anti-citrullinated protein antibody (ACPA)-positive rheumatoid arthritis (RA) and is associated with the development of osteoporotic fractures, according to the results of a microfinite element analysis published in the Annals of the Rheumatic Diseases.
Investigators from the University of Erlangen-Nuremberg in Germany measured failure load and bone stiffness based on computed tomography data in patients with ACPA-positive RA, patients with ACPA-negative RA, and healthy control participants. Total, trabecular, and cortical bone densities, along with microstructural parameters of bone, were also analyzed.
A total of 276 participants were evaluated. Failure load and stiffness of bone were both significantly decreased in patients with ACPA-positive RA (P <.001), but not in those with ACPA-negative RA, compared with healthy control participants. Lower bone strength affected both men and women with ACPA-positive RA and was linked to longer disease duration and was significantly associated with the occurrence of osteoporotic fractures (stiffness of bone, P =.020; failure load, P =.012).
Impaired bone strength was linked to altered bone density and microstructural parameters, both of which were decreased in patients with ACPA-positive RA. According to multivariate models, ACPA status and sex were both independently associated with reduced biomechanical properties of bone in patients with RA (P =.007 and P <.001, respectively).
The investigators concluded that in patients with ACPA-positive RA, bone strength is significantly decreased, which is associated with the risk for fracture. The researchers note that reduced bone strength in patients with ACPA-positive RA is caused by profound changes in bone volumetric density and microarchitecture that resemble the structural features of bone seen in healthy individuals who are 20 years older.
Stemmler F, Simon D, Liphardt AM, et al. Biomechanical properties of bone are impaired in patients with ACPA-positive rheumatoid arthritis and associated with the occurrence of fractures [published online February 23, 2018]. Ann Rheum Dis. doi:10.1136/annrheumdis-2017-212404