title: The predictive value of trabecular bone score (TBS) on whole lumbar vertebrae mechanics: an ex vivo study.
abstract: We investigated the association of trabecular bone score (TBS) with microarchitecture and mechanical behavior of human lumbar vertebrae. We found that TBS reflects vertebral trabecular microarchitecture and is an independent predictor of vertebral mechanics. However, the addition of TBS to areal BMD (aBMD) did not significantly improve prediction of vertebral strength.
  
  
  BACKGROUND
  The trabecular bone score (TBS) is a gray-level measure of texture using a modified experimental variogram which can be extracted from dual-energy X-ray absorptiometry (DXA) images. The current study aimed to confirm whether TBS is associated with trabecular microarchitecture and mechanics of human lumbar vertebrae, and if its combination with BMD improves prediction of fracture risk.
  
  
  METHODS
  Lumbar vertebrae (L3) were harvested fresh from 16 donors. The anteroposterior and lateral bone mineral content (BMC) and areal BMD (aBMD) of the vertebral body were measured using DXA; then, the TBS was extracted using TBS iNsight software (Medimaps SA, France). The trabecular bone volume (Tb.BV/tissue volume, TV), trabecular thickness (Tb.Th), degree of anisotropy, and structure model index (SMI) were measured using microcomputed tomography. Quasi-static uniaxial compressive testing was performed on L3 vertebral bodies to assess failure load and stiffness.
  
  
  RESULTS
  The TBS was significantly correlated to Tb.BV/TV and SMI (r = 0.58 and -0.62; p = 0.02, 0.01), but not related to BMC and BMD. TBS was significantly correlated with stiffness (r = 0.64; p = 0.007), independently of bone mass. Using stepwise multiple regression models, we failed to demonstrate that the combination of BMD and TBS was better at explaining mechanical behavior than either variable alone. However, the combination TBS, Tb.Th, and BMC did perform better than each parameter alone, explaining 79% of the variability in stiffness.
  
  
  CONCLUSIONS
  In our study, TBS was associated with microarchitecture parameters and with vertebral mechanical behavior, but TBS did not improve prediction of vertebral biomechanical properties in addition to aBMD.
authors.affiliation: INSERM, UMR 1033, Université de Lyon, Lyon, France. jean-paul.roux@univ-lyon1.fr
authors.forename: J P
authors.initials: JP
authors.lastname: Roux
authors.forename: J
authors.initials: J
authors.lastname: Wegrzyn
authors.forename: S
authors.initials: S
authors.lastname: Boutroy
authors.forename: M L
authors.initials: ML
authors.lastname: Bouxsein
authors.forename: D
authors.initials: D
authors.lastname: Hans
authors.forename: R
authors.initials: R
authors.lastname: Chapurlat
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density / Q000502:physiology; D019245:Compressive Strength; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000502:physiology; D008297:Male; D008875:Middle Aged; D058866:Osteoporotic Fractures / Q000209:etiology; D011237:Predictive Value of Tests; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D018570:Risk Assessment / Q000379:methods; D016103:Spinal Fractures / Q000209:etiology; D013314:Stress, Mechanical; D055114:X-Ray Microtomography / Q000379:methods