title: The factor-of-risk biomechanical approach predicts hip fracture in men and women: the Framingham Study.
abstract: CONCLUSIONS
  We examined the relation between a biomechanical measure, factor-of-risk, and hip fracture risk in 1,100 men and women from the Framingham Study and found that it predicted hip fracture (men, ORs of 1.8; women, 1.2-1.4).
  
  
  BACKGROUND
  Alternative methods of predicting hip fracture are needed since 50% of adults who fracture do not have osteoporosis by bone mineral density (BMD) measurements. One method, factor-of-risk (Φ), computes the ratio of force on the hip in a fall to femoral strength. We examined the relation between Φ and hip fracture in 1,100 subjects from the Framingham Study with measured hip BMD, along with weight, height, and age, collected in 1988-1989.
  
  
  METHODS
  We estimated both peak and attenuated force applied to the hip in a sideways fall from standing height, where attenuated force incorporated cushioning effects of trochanteric soft tissue. Femoral strength was estimated from femoral neck BMD, using cadaveric femoral strength data. Sex-specific, age-adjusted survival models were used to calculate hazard ratios (HR) and 95% confidence intervals for the relation between Φ (peak), Φ (attenuated), and their components with hip fracture.
  
  
  RESULTS
  In 425 men and 675 women (mean age, 76 years), 136 hip fractures occurred over median follow-up of 11.3 years. Factor-of-risk, Φ, was associated with increased age-adjusted risk for hip fracture. One standard deviation increase in Φ (peak) and Φ (attenuated) was associated with HR of 1.88 and 1.78 in men and 1.23 and 1.41 in women, respectively. Examining components of Φ, in women, we found fall force and soft tissue thickness were predictive of hip fracture independent of femoral strength (was estimated from BMD).
  
  
  CONCLUSIONS
  Thus, both Φ (peak) and Φ (attenuated) predict hip fracture in men and women. These findings suggest additional studies of Φ predicting hip fracture using direct measurements of trochanteric soft tissue.
authors.affiliation: Department of Biostatistics, Boston University School of Public Health, Boston, MA, USA. alyssadufour@hsl.harvard.edu
authors.forename: A B
authors.initials: AB
authors.lastname: Dufour
authors.forename: B
authors.initials: B
authors.lastname: Roberts
authors.forename: K E
authors.initials: KE
authors.lastname: Broe
authors.forename: D P
authors.initials: DP
authors.lastname: Kiel
authors.forename: M L
authors.initials: ML
authors.lastname: Bouxsein
authors.forename: M T
authors.initials: MT
authors.lastname: Hannan
mesh_terms: D000058:Accidental Falls; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D015992:Body Mass Index; D015519:Bone Density / Q000502:physiology; D003238:Connective Tissue / Q000033:anatomy & histology; D005260:Female; D005272:Femur Neck / Q000502:physiology; D006620:Hip Fractures / Q000453:epidemiology / Q000209:etiology* / Q000503:physiopathology; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008404:Massachusetts / Q000453:epidemiology; D018570:Risk Assessment / Q000379:methods*; D013314:Stress, Mechanical