The pathogenesis of bone erosions in gouty arthritis

The characteristic radiographic hallmarks of chronic gouty arthritis are the presence of macroscopic tophi and erosions with overhanging edges and relative preservation of the joint space. In recent years there has been more insight into the processes underlying the development of bone erosions in gouty arthritis. This review discusses the mechanical, pathological, cellular and immunological factors that may have a role in the pathogenesis of bone erosions in gouty arthritis. It highlights the evidence suggesting that monosodium urate crystal deposition is associated with the presence of underlying osteoarthritis and the important role of osteoclasts and the receptor for activation of nuclear factor κ B (RANK) and RANK ligand (RANK-RANKL) pathway in the pathogenesis of gouty erosions. Gouty arthritis is primarily driven by interleukin 1β (IL-1β). IL-1β has been implicated in bone destruction and erosions in other inflammatory arthridities. Thus, future IL-1 inhibitors may prevent and treat erosion formation due to tophaceous gouty arthritis. This review discusses imaging modalities and highlights ultrasongraphic evidence suggesting a significant relationship between the presence of the gouty tophus and bone erosions as well as the frequent presence of persistent low-grade inflammation in asymptomatic chronic tophaceous gouty arthritis on high-resolution ultrasonography. It is the tophus eroding the underlying bone that is pivotal for the development of bone erosions in gouty arthritis.