Efficacy:

To investigate changes of structural bone properties in vivo using 3DpQCT ("Xtreme" CT, Scanco) in monthly oral ibandronate therapy for women with postmenopausal osteoporosis.

Major structural bone parameters which determine bone strength and predict fracture risk earlier and more precisely are measurable in vivo by 3DpQCT.

Safety:

To assess the tolerability and safety of ibandronate therapy

Inclusion Criteria:

• Age between 60 and 75 years
• Menopause > 5 years
• Spine (L1 - L4) or hip BMD ≤ -2.0 and > -3.5 SD T-score measured by DXA
• Patients who, in the opinion of the investigator, are able and willing to comply with the protocol for its duration
• Written informed consent
• 3DpQCT measurable at both skeletal sites, distal tibia and radius

Exclusion Criteria:

• Spine or hip BMD ≤ -3,5 SD T-Score measured by DXA
• Vertebral fractures
• Multiple (>2) low trauma peripheral fractures
• Disease/disorder known to influence bone metabolism
• History of major upper gastro-intestinal (GI) disease
• Diagnosed malignant disease within the previous 10 years
• Previous treatment with a bisphoshonate at any time
• Treatment with fluoride for osteoporosis (dose greater than 10 mg/day) within the last 12 months, or for more than 2 years (total duration)
• Treatment with PTH and similar agents or strontium ranelate at any time
• Treatment with other drugs affecting bone metabolism within the last 6 months
• Chronic systemic corticosteroid treatment
• Estrogens, progestins, SERMs, anabolic steroids, active vitamin D analogues/metabolites, calcitonin
• Calcineurin inhibitors (e.g. cyclosporine, tacrolimus) or methotrexate
• Total serum calcium < 2.2 mmol/l or > 2.6 mmol/l
• Vitamin D deficiency (serum 25-hydroxy vitamin D < 12 ng/ ml)
• ALT above triple upper limit of normal range
• Renal impairment (serum creatinine > 210 µmol/l)
• Contra-indications for ibandronate, calcium or vitamin D
• Employees of the Centre for Muscle and Bone Research, or their relatives