Identical subchondral bone microarchitecture pattern with increased bone resorption in rheumatoid arthritis as compared to osteoarthritis

Abstract

To analyze the differences in microarchitecture and bone remodeling of subchondral bone in femoral heads from patients with rheumatoid arthritis (RA) and osteoarthritis (OA). Peri-articular bone samples, including subchondral trabecular bone (STB) and deeper trabecular bone (DTB) were extracted from the load-bearing region of femoral heads from 20 patients with RA and 40 patients with OA during hip replacement surgery. Micro-CT, histomorphometry and backscatter scanning electron microscopy (BSEM) were performed to assess microarchitecture and bone histology parameters. In both RA and OA, STB showed more sclerotic microarchitecture and more active bone remodeling, compared to DTB. RA and OA showed similar microarchitecture characteristics in both STB and DTB, despite STB in RA exhibiting higher bone resorption. In addition, there was no difference in the frequency of bone cysts in STB between RA and OA. In STB, the trabecular bone surrounding subchondral bone cysts (Cys-Tb) was more sclerotic than the trabecular bone found distant to cysts (Peri-Tb), with a higher level of bone remodeling. Both Cys-Tb region and Peri-Tb region were detected to have similar microarchitectural and bone remodeling characteristics in RA and OA. Apart from higher bone resorption in the general subchondral bone of RA samples, the peri-articular bone exhibited similar microarchitectural and bone remodeling characteristics in RA and OA.