title: Spine Trabecular Bone Score as an Indicator of Bone Microarchitecture at the Peripheral Skeleton in Kidney Transplant Recipients.
abstract: OBJECTIVE
  Studies using high-resolution peripheral quantitative computed tomography showed progressive abnormalities in cortical and trabecular microarchitecture and biomechanical competence over the first year after kidney transplantation. However, high-resolution peripheral computed tomography is a research tool lacking wide availability. In contrast, the trabecular bone score is a novel and widely available tool that uses gray-scale variograms of the spine image from dual-energy x-ray absorptiometry to assess trabecular quality. There are no studies assessing whether trabecular bone score characterizes bone quality in kidney transplant recipients.
  
  
  METHODS
  Between 2009 and 2010, we conducted a study to assess changes in peripheral skeletal microarchitecture, measured by high-resolution peripheral computed tomography, during the first year after transplantation in 47 patients managed with early corticosteroid-withdrawal immunosuppression. All adult first-time transplant candidates were eligible. Patients underwent imaging with high-resolution peripheral computed tomography and dual-energy x-ray absorptiometry pretransplantation and 3, 6, and 12 months post-transplantation. We now test if, during the first year after transplantation, trabecular bone score assesses the evolution of bone microarchitecture and biomechanical competence as determined by high-resolution peripheral computed tomography.
  
  
  RESULTS
  At baseline and follow-up, among the 72% and 78%, respectively, of patients having normal bone mineral density by dual-energy x-ray absorptiometry, 53% and 50%, respectively, were classified by trabecular bone score as having high fracture risk. At baseline, trabecular bone score correlated with spine, hip, and ultradistal radius bone mineral density by dual-energy x-ray absorptiometry and cortical area, density, thickness, and porosity; trabecular density, thickness, separation, and heterogeneity; and stiffness and failure load by high-resolution peripheral computed tomography. Longitudinally, each percentage increase in trabecular bone score was associated with increases in trabecular number (0.35%±1.4%); decreases in trabecular thickness (-0.45%±0.15%), separation (-0.40%±0.15%), and network heterogeneity (-0.48%±0.20%); and increases in failure load (0.22%±0.09%) by high-resolution peripheral computed tomography (allP<0.05).
  
  
  CONCLUSIONS
  Trabecular bone score may be a useful method to assess and monitor bone quality and strength and classify fracture risk in kidney transplant recipients.
authors.affiliation: Institute of Human Nutrition and Departments of.
authors.forename: Matthew
authors.initials: M
authors.lastname: Luckman
authors.affiliation: Center of Bone Diseases, Bone and Joint Department, Medical University of Lausanne, Lausanne, Switzerland.
authors.forename: Didier
authors.initials: D
authors.lastname: Hans
authors.affiliation: Medicine and.
authors.forename: Natalia
authors.initials: N
authors.lastname: Cortez
authors.affiliation: Medicine and.
authors.forename: Kyle K
authors.initials: KK
authors.lastname: Nishiyama
authors.affiliation: Medicine and.
authors.forename: Sanchita
authors.initials: S
authors.lastname: Agarawal
authors.affiliation: Medicine and.
authors.forename: Chengchen
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Orthopaedics and Rehabilitation, University of Rochester, Rochester, New York.
authors.forename: Lucas
authors.initials: L
authors.lastname: Nikkel
authors.affiliation: Department of Medicine, Kaiser Oakland Medical Center, Oakland, California; and.
authors.forename: Sapna
authors.initials: S
authors.lastname: Iyer
authors.affiliation: Institute of Clinical Physiology, National Research Council, Pisa, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: Fusaro
authors.affiliation: Biomedical Engineering, Columbia University, New York, New York.
authors.forename: Edward X
authors.initials: EX
authors.lastname: Guo
authors.affiliation: Medicine and.
authors.forename: Donald J
authors.initials: DJ
authors.lastname: McMahon
authors.affiliation: Medicine and.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Shane
authors.affiliation: Medicine and.
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Nickolas
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D015519:Bone Density; D000071556:Cancellous Bone / Q000000981:diagnostic imaging*; D005260:Female; D005270:Femur Head / Q000000981:diagnostic imaging; D006801:Humans; D016030:Kidney Transplantation; D008297:Male; D008875:Middle Aged; D016062:Porosity; D011884:Radius / Q000000981:diagnostic imaging; D013131:Spine / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed / Q000379:methods; D055815:Young Adult
keywords: Absorptiometry, Photon; Adrenal Cortex Hormones; Adult; Bone Density; Bone and Bones; Follow-Up Studies; Fractures, Bone; Humans; Porosity; Radius; Spine; Tomography; kidney transplantation; mineral metabolism; renal osteodystrophy; renal transplantation