Paget's disease of bone (PDB) affects up to 1% of people of European origin aged 55 years and above. It is characterized by focal abnormalities of bone remodelling which disrupt normal bone architecture, leading to expansion and reduced mechanical strength of affected bones. This can lead to various complications including deformity, fracture, nerve compression syndromes, and osteoarthritis, although many patients are asymptomatic. Genetic factors play a key role in the pathogenesis of PDB. This seems to be mediated by a combination of rare genetic variants which cause familial forms of the disease and common variants which increase susceptibility to environmental triggers. Environmental factors which have been suggested to predispose to PDB include viral infections, calcium and vitamin D deficiency, and excessive mechanical loading of affected bones. The diagnosis can be made by the characteristic changes seen on radiographs, but isotope bone scans are helpful in defining disease extent. Serum alkaline phosphatase levels can be used as a measure of disease activity. Inhibitors of bone resorption are the mainstay of medical management for PDB and bisphosphonates are regarded as the treatment of choice. Bisphosphonates are highly effective at reducing bone turnover in PDB and have been found to heal osteolytic lesions, and normalize bone histology. Although bisphosphonates can improving bone pain caused by elevated bone turnover, most patients require additional therapy to deal with symptoms associated with disease complications. It is currently unclear whether bisphosphonate therapy is effective at preventing complications of PDB.
Long-term biochemical response after bisphosphonate therapy in Paget's disease of bone. Proposed intervals for monitoring treatment
