Clinical insights into the role of smoking, diabetes, and rheumatoid arthritis in osteoporotic fractures.

Background: Osteoporotic fractures pose a significant public health challenge, with various risk factors contributing to their incidence. Smoking, diabetes mellitus (DM), and rheumatoid arthritis (RA) are known to disrupt bone metabolism and increase fracture susceptibility. Moreover, smoking is a well-known risk factor of DM and RA, and thereby imposes a greater impact on osteoporotic fractures. This review explores the impact of these conditions on osteoporotic fractures, emphasizing the underlying mechanisms and clinical implications.

Methods: A comprehensive literature review was conducted to examine the biochemical and physiological effects of smoking, DM, and RA on bone metabolism. The review focused on key regulatory pathways, including the role of parathyroid hormone (PTH), vitamin D, receptor activator of nuclear factor kappa-B ligand (RANKL), osteoprotegerin (OPG), and inflammatory cytokines.

Results: Smoking contributes to osteoporotic fractures by altering bone metabolism through multiple mechanisms, including dysregulation of PTH, vitamin D, and the RANKL/OPG balance. RA disrupts bone homeostasis by increasing osteoclast activity, reducing osteoblast function, and elevating pro-inflammatory cytokines such as IL-1, IL-6, and TNF-α. Additionally, RA treatment with glucocorticoids further impairs calcium balance and bone integrity. DM accelerates bone resorption by upregulating osteoclastogenic factors (e.g., TNF-α, VEGF, RANKL) and suppressing osteoblastogenic pathways (e.g., Runx2). It also reduces essential bone-forming substances, including PTH and osteocalcin, while promoting the accumulation of advanced glycation end-products and adiposity, both of which negatively impact bone health.

Conclusions: Smoking, DM, and RA significantly contribute to osteoporotic fractures by disrupting bone metabolism through direct biochemical alterations and treatment-related effects. Furthermore, smoking exacerbates both DM and RA, compounding the risk of fractures. Effective clinical management of these risk factors is essential to reducing the burden of osteoporotic fractures and improving patient outcomes.