title: Bisphosphonate-related complete atypical subtrochanteric femoral fractures: diagnostic utility of radiography.
abstract: OBJECTIVE
  The objective of our study was to evaluate the diagnostic utility of conventional radiography for diagnosing bisphosphonate-related atypical subtrochanteric femoral fractures.
  
  
  METHODS
  Retrospective interpretation of 38 radiographs of complete subtrochanteric and diaphyseal femoral fractures in two patient groups-one group being treated with bisphosphonates (19 fractures in 17 patients) and a second group not being treated with bisphosphonates (19 fractures in 19 patients)-was performed by three radiologists. The readers assessed four imaging criteria: focal lateral cortical thickening, transverse fracture, medial femoral spike, and fracture comminution. The odds ratios and the sensitivity, specificity, and accuracy of each imaging criterion as a predictor of bisphosphonate-related fractures were calculated. Similarly, the interobserver agreement and the sensitivity, specificity, and accuracy of diagnosing bisphosphonate-related fractures (i.e., atypical femoral fractures) were determined for the three readers.
  
  
  RESULTS
  Among the candidate predictors of bisphosphonate-related fractures, focal lateral cortical thickening and transverse fracture had the highest odds ratios (76.4 and 10.1, respectively). Medial spike and comminution had odd ratios of 3.8 and 0.63, respectively. Focal lateral cortical thickening and transverse fracture were also the most accurate factors for detecting bisphosphonate-related fractures for all readers. The sensitivity, specificity, and overall accuracy for diagnosing bisphosphonate-related fractures were 94.7%, 100%, and 97.4% for reader 1; 94.7%, 68.4%, and 81.6% for reader 2; and 89.5%, 89.5%, and 89.5% for reader 3, respectively. The interobserver agreement was substantial (κ > 0.61).
  
  
  CONCLUSIONS
  Radiographs are reliable for distinguishing between complete femoral fractures related to bisphosphonate use and those not related to bisphosphonate use. Focal lateral cortical thickening and transverse fracture are the most dependable signs, showing high odds ratios and the highest accuracy for diagnosing these fractures.
authors.affiliation: Department of Radiology, New York University Hospital for Joint Diseases, 301 E 17th St, 6th Fl, New York, NY 10003-3899, USA.
authors.forename: Zehava Sadka
authors.initials: ZS
authors.lastname: Rosenberg
authors.forename: Renata
authors.initials: R
authors.lastname: La Rocca Vieira
authors.forename: Sarah S
authors.initials: SS
authors.lastname: Chan
authors.forename: James
authors.initials: J
authors.lastname: Babb
authors.forename: Yakup
authors.initials: Y
authors.lastname: Akyol
authors.forename: Leon D
authors.initials: LD
authors.lastname: Rybak
authors.forename: Sandra
authors.initials: S
authors.lastname: Moore
authors.forename: Jenny T
authors.initials: JT
authors.lastname: Bencardino
authors.forename: Valerie
authors.initials: V
authors.lastname: Peck
authors.forename: Nirmal C
authors.initials: NC
authors.lastname: Tejwani
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Egol
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D050071:Bone Density Conservation Agents / Q000009:adverse effects*; D004164:Diphosphonates / Q000009:adverse effects*; D005260:Female; D006620:Hip Fractures / Q000139:chemically induced* / Q000000981:diagnostic imaging*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011859:Radiography; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D050071:Bone Density Conservation Agents; D004164:Diphosphonates