title: The effect of physical loading on calcaneus quantitative ultrasound measurement: a cross-section study.
abstract: BACKGROUND
  Physical loading leads to a deformation of bone microstructure and may influence quantitative ultrasound (QUS) parameters. This study aims at evaluating the effect of physical loading on bone QUS measurement, and further, on the potential of diagnosing osteoporosis using QUS method under physical loading condition.
  
  
  METHODS
  16 healthy young females (control group) and 45 postmenopausal women (divided into 3 groups according to the years since menopause (YSM)) were studied. QUS parameters were measured at calcaneus under self-weight loading (standing) and no loading (sitting) conditions. Weight-normalized QUS parameter (QUS parameter measured under loading condition divided by the weight of the subject) was proposed to evaluate the influence of loading. T-test, One-Way analysis of variance (one way ANOVA) and receiver operating characteristic (ROC) analysis were applied for analysis.
  
  
  RESULTS
  In QUS parameters, mainly normalized broadband ultrasound attenuation (nBUA), measured with loading significantly differed from those measured without loading (p < 0.05). The relative changes of weight-normalized QUS parameters on postmenopausal women with respect to premenopausal women under loading condition were larger than those on traditional QUS parameters measured without loading. In ROC analysis, weight-normalized QUS parameters showed their stronger discriminatory ability for menopause.
  
  
  CONCLUSIONS
  Physical loading substantially influenced bone QUS measurement (mainly nBUA). Weight-normalized QUS parameters can discriminate menopause more effectively. By considering the high relationship between menopause and osteoporosis, an inference was drawn that adding physical loading during measurement may be a probable way to improve the QUS based osteoporosis diagnosis.
authors.affiliation: Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, People's Republic of China.
authors.forename: Cheng-Rui
authors.initials: CR
authors.lastname: Liu
authors.forename: Hai-Jun
authors.initials: HJ
authors.lastname: Niu
authors.forename: Fang
authors.initials: F
authors.lastname: Pu
authors.forename: Ling
authors.initials: L
authors.lastname: Wang
authors.forename: Lian-Wen
authors.initials: LW
authors.lastname: Sun
authors.forename: Yu-Bo
authors.initials: YB
authors.lastname: Fan
authors.forename: De-Yu
authors.initials: DY
authors.lastname: Li
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D002111:Calcaneus / Q000000981:diagnostic imaging* / Q000473:pathology / Q000502:physiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000000981:diagnostic imaging* / Q000473:pathology; D017698:Postmenopause; D011237:Predictive Value of Tests; D012372:ROC Curve; D013314:Stress, Mechanical; D014463:Ultrasonography / Q000379:methods*; D016474:Weight-Bearing / Q000502:physiology*; D055815:Young Adult