Original Article

Osteoporosis International

, Volume 21, Issue 7, pp 1277-1285

First online:

Effect of once-yearly zoledronic acid on the spine and hip as measured by quantitative computed tomography: results of the HORIZON Pivotal Fracture Trial

  • R. EastellAffiliated withAcademic Unit of Bone Metabolism, University of SheffieldMetabolic Bone Centre, Sorby Wing, Northern General Hospital Email author 
  • , T. LangAffiliated withDepartment of Radiology, University of California
  • , S. BoonenAffiliated withLeuven University Centre for Metabolic Bone Diseases and Division of Geriatric Medicine, Katholieke Universiteit Leuven
  • , S. CummingsAffiliated withCPMC Research Institute, University of California
  • , P. D. DelmasAffiliated withINSERM Research Unit 831 and University of Lyon
  • , J. A. CauleyAffiliated withDepartment of Epidemiology, University of Pittsburgh
  • , Z. HorowitzAffiliated withSavient Pharmaceuticals
  • , E. KerzbergAffiliated withArgentine Reference Center in Osteoporosis, Hospital Ramos Mejía
  • , G. BianchiAffiliated withDivision of Rheumatology, La Colletta Hospital
    • , D. KendlerAffiliated withOsteoporosis Research Centre
    • , P. LeungAffiliated withFaculty of Medicine, Chinese University of Hong Kong, Prince of Wales Hospital
    • , Z. ManAffiliated withCentro TIEMPO, Universidad Favaloro
    • , P. MesenbrinkAffiliated withNovartis Pharmaceuticals Corporation
    • , E. F. EriksenAffiliated withDepartment of Endocrinology, Aker University Hospital
    • , D. M. BlackAffiliated withDepartment of Epidemiology and Biostatistics, University of California
    • , for the HORIZON Pivotal Fracture Trial

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Changes in bone mineral density and bone strength following treatment with zoledronic acid (ZOL) were measured by quantitative computed analysis (QCT) or dual-energy X-ray absorptiometry (DXA). ZOL treatment increased spine and hip BMD vs placebo, assessed by QCT and DXA. Changes in trabecular bone resulted in increased bone strength.


To investigate bone mineral density (BMD) changes in trabecular and cortical bone, estimated by quantitative computed analysis (QCT) or dual-energy X-ray absorptiometry (DXA), and whether zoledronic acid 5 mg (ZOL) affects bone strength.


In 233 women from a randomized, controlled trial of once-yearly ZOL, lumbar spine, total hip, femoral neck, and trochanter were assessed by DXA and QCT (baseline, Month 36). Mean percentage changes from baseline and between-treatment differences (ZOL vs placebo, t-test) were evaluated.


Mean between-treatment differences for lumbar spine BMD were significant by DXA (7.0%, p < 0.01) and QCT (5.7%, p < 0.0001). Between-treatment differences were significant for trabecular spine (p = 0.0017) [non-parametric test], trabecular trochanter (10.7%, p < 0.0001), total hip (10.8%, p < 0.0001), and compressive strength indices at femoral neck (8.6%, p = 0.0001), and trochanter (14.1%, p < 0.0001).


Once-yearly ZOL increased hip and spine BMD vs placebo, assessed by QCT vs DXA. Changes in trabecular bone resulted in increased indices of compressive strength.


Bisphosphonates Bone densitometry Bone QCT Clinical trials Osteoporosis