title: Are women with thicker cortices in the femoral shaft at higher risk of subtrochanteric/diaphyseal fractures? The study of osteoporotic fractures.
abstract: BACKGROUND
  Femoral shaft cortical thickening has been mentioned in reports of atypical subtrochanteric and diaphyseal (S/D) femur fractures, but it is unclear whether thickening precedes fracture or results from a preceding stress fracture and what role bisphosphonates might play in cortical thickening.
  
  
  OBJECTIVE
  Our objective was to examine the relationship of cortical thickness to S/D fracture risk as well as establish normal reference values for femoral cortical thickness in a large population-based cohort of older women.
  
  
  METHODS
  Using pelvic radiographs obtained in 1986-1988, we measured femoral shaft cortical thickness 3 cm below the lesser trochanter in women in the Study of Osteoporotic Fractures. We measured this in a random sample and in those with S/D fractures and femoral neck and intertrochanteric fractures. Low-energy S/D fractures were identified from review of radiographic reports obtained between 1986 and 2010. Radiographs to evaluate atypia were not available. Analysis used case-cohort, proportional hazards models.
  
  
  RESULTS
  Cortical thickness as a risk factor for low-energy S/D femur fractures as well as femoral neck and intertrochanteric fractures in the Study of Osteoporotic Fractures, adjusting for age and bone mineral density in proportional hazards models.
  
  
  RESULTS
  After age adjustment, women with thinner medial cortices were at a higher risk of S/D femur fracture, with a relative hazard of 3.94 (95% confidence interval = 1.23-12.6) in the lowest vs. highest quartile. Similar hazard ratios were seen for femoral neck and intertrochanteric fractures. Medial or total cortical thickness was more strongly related to fracture risk than lateral cortical thickness.
  
  
  CONCLUSIONS
  In primarily bisphosphonate-naive women, we found no evidence that thick femoral cortices placed women at higher risk for low-energy S/D femur fractures; in fact, the opposite was true. Women with thin cortices were also at a higher risk for femoral neck and intertrochanteric fractures. Whether cortical thickness among bisphosphonate users plays a role in atypical S/D fractures remains to be determined.
authors.affiliation: Universita` Campus Bio-Medico di Roma, Roma, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Napoli
authors.forename: Jenny
authors.initials: J
authors.lastname: Jin
authors.forename: Katherine
authors.initials: K
authors.lastname: Peters
authors.forename: Rosanna
authors.initials: R
authors.lastname: Wustrack
authors.forename: Shane
authors.initials: S
authors.lastname: Burch
authors.forename: Aldric
authors.initials: A
authors.lastname: Chau
authors.forename: Jane
authors.initials: J
authors.lastname: Cauley
authors.forename: Kristine
authors.initials: K
authors.lastname: Ensrud
authors.forename: Michael
authors.initials: M
authors.lastname: Kelly
authors.forename: Dennis M
authors.initials: DM
authors.lastname: Black
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D015519:Bone Density / Q000502:physiology; D015331:Cohort Studies; D018483:Diaphyses / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000293:injuries* / Q000473:pathology; D005260:Female; D005264:Femoral Fractures / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology*; D005269:Femur / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000473:pathology; D005272:Femur Neck / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000473:pathology; D006620:Hip Fractures / Q000453:epidemiology / Q000209:etiology* / Q000473:pathology; D006801:Humans; D015663:Osteoporosis, Postmenopausal / Q000150:complications / Q000000981:diagnostic imaging / Q000453:epidemiology; D058866:Osteoporotic Fractures / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology*; D011859:Radiography; D012189:Retrospective Studies; D012307:Risk Factors