title: Atypical incomplete femoral fractures in asymptomatic patients on long term bisphosphonate therapy.
abstract: OBJECTIVE
  Progression of an incomplete atypical femoral fracture (IF) to a complete fracture in patients on long term bisphosphonate (BP) therapy can be catastrophic. We aimed to determine the frequency and imaging features of IF in asymptomatic patients on long-term BP therapy and to identify distinguishing clinical and laboratory markers in the subset of patients who develop these fractures.
  
  
  METHODS
  From August 2009 to March 2011, 220 femoral radiographs in 110 asymptomatic patients (101 women, 9 men, age 47-94) were reviewed by 2 radiologists. All patients were on BP therapy for at least 3 years and had no history of hip/thigh pain or recent trauma. MRI was performed when a fracture was suspected on radiographs. Bone mineral density, serum calcium, 25-hydroxy vitamin D, intact parathyroid hormone, serum c-telopeptide and urine n-telopeptide were obtained in all patients.
  
  
  RESULTS
  Two of 110 patients (1.82%, confidence interval of 0.6% to 6.3%) had 3 IFs. Both patients, age 50 and 57, were Caucasian, active and on BP for 8 years. MRI confirmed radiographic findings in both patients. Both women had T-scores in the osteopenic range at 2 sites and osteoporotic range at 1 site.
  
  
  CONCLUSIONS
  The 1.82% frequency of IF in asymptomatic patients on long term BP therapy is higher than that suggested in the literature. Statistical differences between fracture and non-fracture groups were not presented as the patient population was too small to draw any significant conclusions.
authors.affiliation: NYU Langone Medical Center, USA.
authors.forename: M B
authors.initials: MB
authors.lastname: Allison
authors.forename: L
authors.initials: L
authors.lastname: Markman
authors.forename: Z
authors.initials: Z
authors.lastname: Rosenberg
authors.forename: R L
authors.initials: RL
authors.lastname: Vieira
authors.forename: J
authors.initials: J
authors.lastname: Babb
authors.forename: N
authors.initials: N
authors.lastname: Tejwani
authors.forename: V
authors.initials: V
authors.lastname: Peck
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016001:Confidence Intervals; D004164:Diphosphonates / Q000009:adverse effects*; D005260:Female; D005264:Femoral Fractures / Q000139:chemically induced* / Q000000981:diagnostic imaging / Q000473:pathology; D005269:Femur / Q000000981:diagnostic imaging / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011859:Radiography
chemical_list: D004164:Diphosphonates