title: A two-level subject-specific biomechanical model for improving prediction of hip fracture risk.
abstract: BACKGROUND
  Sideways fall-induced hip fracture is a major worldwide health problem among the elderly population. However, all existing biomechanical models for predicting hip fracture mainly consider the femur related parameters. Their accuracy is limited as hip fracture is significantly affected by loading conditions as well. The objective of this study was to develop a biomechanical model for improving assessment of hip fracture risk by subject-specific prediction of fall-induced loading conditions.
  
  
  METHODS
  All information required to construct the models was extracted from the subject's whole-body and hip medical image in order to make the models subject-specific. Fall-induced hip fracture risk for eighty clinical cases was calculated under two sets of loading conditions: subject-specific determined by the proposed model, and non-subject-specific obtained from empirical functions. The predicted hip fracture risk indices were then compared with clinical observations.
  
  
  RESULTS
  It was found that the subject-specific prediction of fall-induced loading conditions significantly improves the hip fracture risk assessment. Consistent to the clinical observations, the fracture risk predicted by the proposed model suggested that obesity is a protective factor for hip fracture and underweight subjects are more likely to experience a hip fracture.
  
  
  CONCLUSIONS
  This study shows that hip fracture risk is affected by a number of factors, including body weight, body height, impact force, body mass index, hip soft tissue thickness, and bone quality. The proposed model provides a comprehensive, fast, accurate, and non-expensive method for prediction of hip fracture risk which should lead to more effective prevention of hip fractures.
authors.affiliation: Department of Mechanical Engineering, Faculty of Engineering, University of Manitoba, 75A Chancellors Circle, Winnipeg, Manitoba R3T 2N2, Canada.
authors.forename: Masoud Nasiri
authors.initials: MN
authors.lastname: Sarvi
authors.affiliation: Department of Mechanical Engineering, Faculty of Engineering, University of Manitoba, 75A Chancellors Circle, Winnipeg, Manitoba R3T 2N2, Canada. Electronic address: Yunhua.Luo@umnitoba.ca.
authors.forename: Yunhua
authors.initials: Y
authors.lastname: Luo
mesh_terms: D000058:Accidental Falls / Q000517:prevention & control*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000886:Anthropometry; D001696:Biomechanical Phenomena; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D005260:Female; D005269:Femur / Q000502:physiology*; D020342:Finite Element Analysis; D006620:Hip Fractures / Q000175:diagnosis* / Q000517:prevention & control*; D006801:Humans; D008875:Middle Aged; D008962:Models, Theoretical; D009765:Obesity / Q000150:complications; D010384:Pelvic Bones; D018570:Risk Assessment / Q000379:methods*; D055815:Young Adult
keywords: Fracture risk index; Hip fracture; Impact force; Sideways fall; Subject-specific; Two-level