title: Association of atypical femoral fractures with bisphosphonate use by patients with varus hip geometry.
abstract: BACKGROUND
  There is increasing evidence associating "atypical" femoral fractures with prolonged exposure to bisphosphonate therapy. The cause of these fractures is unknown and likely multifactorial. This study evaluated the hypothesis that patients with primary osteoporosis who sustain atypical femoral fracture(s) while on chronic bisphosphonate therapy have a more varus proximal femoral geometry than patients who use bisphosphonates for primary osteoporosis but do not sustain a femoral fracture.
  
  
  METHODS
  The femoral neck-shaft angle was measured on the radiographs of 111 patients with atypical femoral shaft fracture(s) and thirty-three asymptomatic patients; both groups were on chronic bisphosphonate therapy. Patients with characteristic lateral cortical thickening, stress lines, and thigh pain were included in the fracture group.
  
  
  RESULTS
  The mean neck-shaft angle of the patients who sustained atypical femoral fracture(s) while taking bisphosphonates (case group) differed significantly from that of the patients on bisphosphonate therapy without a fracture (129.5° versus 133.8°; p < 0.001). Fifty-three (48%) of the patients in the case group had a neck-shaft angle that was lower than the lowest angle in the control group (128°). Side-to-side comparison in patients with a unilateral pathologic involvement and an asymptomatic contralateral lower limb did not demonstrate any significant difference between the neck-shaft angles in the two limbs.
  
  
  CONCLUSIONS
  Patients on chronic bisphosphonate therapy who presented with atypical femoral fracture(s) had more varus proximal femoral geometry than those who took bisphosphonates without sustaining a fracture. Although no causative effect can be determined, a finding of varus geometry may help to better identify patients at risk for fracture after long-term bisphosphonate use.
authors.affiliation: University of Maryland, 22 South Greene Street, Baltimore, MD 21202. E-mail address: Jeh29@case.edu.
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Hagen
authors.affiliation: Wake Forest Baptist Health, 131 Miller Street, Winston-Salem, NC 27103.
authors.forename: Anna N
authors.initials: AN
authors.lastname: Miller
authors.affiliation: University of Washington, 4245 Roosevelt Way N.E., Box 35470, Seattle, WA 98105.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Ott
authors.affiliation: Washington University, 4921 Parkview Place, St. Louis, MO 63110.
authors.forename: Michael
authors.initials: M
authors.lastname: Gardner
authors.affiliation: University of California San Francisco, 2550 23rd Street, San Francisco, CA 94110.
authors.forename: Saam
authors.initials: S
authors.lastname: Morshed
authors.affiliation: Steadman Hawkins Clinic, 200 Patewood Drive, Suite C100, Greenville, SC 29615.
authors.forename: Kyle
authors.initials: K
authors.lastname: Jeray
authors.affiliation: University of Washington, 1959 N.E. Pacific Street, #356500, Seattle, WA 98195.
authors.forename: Timothy B
authors.initials: TB
authors.lastname: Alton
authors.affiliation: Tulane School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112.
authors.forename: Dennis
authors.initials: D
authors.lastname: Ren
authors.affiliation: Wake Forest School of Medicine, Medical Center Boulevard, Winston Salem, NC 27157.
authors.forename: W Parker
authors.initials: WP
authors.lastname: Abblitt
authors.affiliation: The Rothman Institute, Jefferson University, 925 Chestnut Street, Philadelphia, PA 19107.
authors.forename: James C
authors.initials: JC
authors.lastname: Krieg
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D050071:Bone Density Conservation Agents / Q000009:adverse effects* / Q000627:therapeutic use; D016022:Case-Control Studies; D004164:Diphosphonates / Q000009:adverse effects* / Q000627:therapeutic use; D005260:Female; D005264:Femoral Fractures / Q000139:chemically induced* / Q000209:etiology; D006621:Hip Joint / Q000033:anatomy & histology*; D006801:Humans; D008875:Middle Aged; D010024:Osteoporosis / Q000150:complications / Q000188:drug therapy*; D012189:Retrospective Studies; D012307:Risk Factors
chemical_list: D050071:Bone Density Conservation Agents; D004164:Diphosphonates