Osteoporosis in inflammatory joint diseases

Rheumatoid arthritis (RA) and ankylosing spondylitis (AS) are two inflammatory joint diseases characterized by bone complications including osteoporosis. In RA, periarticular bone loss, bone erosions, and systemic osteoporosis are observed, with an increased risk of fractures. Determinants of fractures are underlying conditions (as RA has a female preponderance and an increased prevalence with age), severity of the disease, and use of glucocorticoids. However, bone loss can occur even in glucocorticoid-naive patients. Prospective data show that the optimal control of inflammation in RA is associated with decrease in structural damage and bone loss. RA illustrates the role of inflammation on bone resorption. In AS, osteoporosis is an early event and vertebral fracture risk is increased. Bone loss is related mainly to inflammation, as the disease can occur in young male adult populations, and glucocorticoids are not used in this disease. However, AS is characterized by progressive stiffness and ankylosis of the spine and illustrates also the potential role of inflammation on local bone formation.