Study of the Effect of Once a Week Risedronate on the Microstructure of Tibia and Radius Using a New Scanning Method

Inclusion Criteria: * cessation of menstruation (surgical or natural) between 6 and 36 months prior to study enrollment; * osteopenic * must have at least 1 evaluable radius and tibia, without history of fracture (traumatic or atraumatic) * BMI (body mass index) between 18 and 28 kg/m2 inclusive; Exclusion Criteria: * history of any generalized bone disease, including hyperparathyroidism, Paget's disease of bone, renal osteodystrophy, or any other acquired or congenital bone disease; or any known condition that would interfere with the assessment of DXA (dual-energy X-ray absorptiometry) at either the lumbar spine (3 non-evaluable lumbar vertebrae at lumbar spine L1 - L4) or the femoral neck. * clinical or radiological evidence of osteoporosis, such as atraumatic vertebral compression fracture (\* 20% reduction in anterior-to-posterior or middle-to-posterior height ratio; or 20% reduction of the anterior, middle, and/or posterior height as compared with the adjacent vertebrae) documented by spinal X ray or a history of osteoporosis-related atraumatic fracture of the hip or of the wrist; * glucocorticoid-induced osteopenia; * previous bisphosphonate therapy;