Effect of Risedronate on Bone Morbidity in Fibrous Dysplasia of Bone

Inclusion Criteria: * Study I: patients with FD, with bone pain intensity above 3 on visual analogical scale from 0 to 10 * Study II: patients with FD with at least one osteolytic lesion and no current bone pain Exclusion Criteria: * patients \< 8 years old * other diseases affecting bone metabolism * patients with malignant diseases or other conditions likely to reduce their life expectancy to less than 3 years * patients with history of significant upper gastrointestinal disorders * renal failure (creatinine clearance \< 25 ml/mn) * severe liver disease * history of iritis or uveitis * rickets or osteomalacia * allergy to bisphosphonates * pregnancy or lactation * prior treatment with a bisphosphonate * laboratory abnormalities that may be considered as clinically significant by trial physicians