The significance of insufficiency fractures in rheumatic musculoskeletal diseases

Osteoporosis is a systemic skeletal disease characterized by low bone mineral density (BMD) and poor bone quality, leading to reduced bone strength and increased risk of fracture. In rheumatic and musculoskeletal diseases (RMD), including rheumatoid arthritis (RA) and spondyloarthritides (SpA), such as axial spondyloarthritis (axSpA) and psoriatic arthritis (PsA), generalized bone loss associated with traumatic and non-traumatic fractures, such as insufficiency fractures (IF), is known to occur with the RANK-RANKL-osteoprotegerin axis and the Wnt-β-catenin signalling pathway playing a pathogenetic role. RA has been included in the Fracture Risk Assessment Tool (FRAX) system to be able to more precisely calculate the 10-year fracture risk associated with the disease. Various definitions for IF have been proposed; a recent paper by the EMA has defined fragility fractures as fractures occurring with low trauma at the hip, spine, pelvis, distal femur, proximal tibia, humerus, forearm, and multiple ribs. However, IF of the feet are currently not considered osteoporotic fractures. So-called stress fractures, which are known to often occur in athletes, have a similar MRI appearance. However, these are rather due to repetitive strain than to minor trauma. Also, based on recent data, this manuscript concentrates on the significance of fragility fractures in RMD.