title: Healing of Atypical Subtrochanteric Femur Fractures After Cephalomedullary Nailing: Which Factors Predict Union?
abstract: OBJECTIVE
  The purpose of this study was to determine the healing rate and time to union of atypical subtrochanteric fractures treated with cephalomedullary nailing.
  
  
  METHODS
  Retrospective review, descriptive, and analytic study.
  
  
  METHODS
  Six level 1 trauma centers.
  
  
  METHODS
  The study included 42 patients with 48 displaced, atypical, bisphosphonate-associated subtrochanteric femur fractures who underwent surgical intervention.
  
  
  METHODS
  Cephalomedullary femur nailing.
  
  
  METHODS
  The main outcome measures were radiologic healing and time to union.
  
  
  RESULTS
  The primary healing rate after cephalomedullary nailing of bisphosphonate-associated subtrochanteric femur fractures was 68.7% (33/48 patients). Mean time to union was 10.7 months. Malalignment was determined using the differences in neck-shaft angle (the difference between the normal side and the surgically repaired side) and sagittal angulation. These all proved to be significantly correlated with failure and delayed healing time. The cutoff points for neck-shaft angle, difference in neck-shaft angle, and sagittal angulation were 125.6, 4.4, and 5.5 degrees, respectively (receiver operating characteristic curve analysis).
  
  
  CONCLUSIONS
  The healing rate of atypical subtrochanteric femur fractures treated with cephalomedullary nailing is lower than that previously reported for atypical femur fractures. The quality of fracture reduction proved to be the most important factor in bony union and time to union.
  
  
  METHODS
  Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
authors.affiliation: *Department of Orthopaedic Surgery, Guro Hospital, Korea University Medical Center, Seoul, Korea; †Department of Orthopaedic Surgery, Kyungpook National University Hospital, Daegu, Korea; ‡Department of Orthopaedic Surgery, Queen Mary Hospital, Hong Kong, China; §Department of Orthopaedic Surgery, Hanyang University Guri Hospital, Guri-si, Korea; ‖Department of Orthopaedic Surgery, Singapore General Hospital, Singapore; and ¶Department of Orthopaedic Surgery, Tan Tock Seng Hospital, Singapore.
authors.forename: Jae-Woo
authors.initials: JW
authors.lastname: Cho
authors.forename: Chang-Wug
authors.initials: CW
authors.lastname: Oh
authors.forename: Frankie
authors.initials: F
authors.lastname: Leung
authors.forename: Ki-Chul
authors.initials: KC
authors.lastname: Park
authors.forename: Merng Koon
authors.initials: MK
authors.lastname: Wong
authors.forename: Ernest
authors.initials: E
authors.lastname: Kwek
authors.forename: Han-Ju
authors.initials: HJ
authors.lastname: Kim
authors.forename: Jong-Keon
authors.initials: JK
authors.lastname: Oh
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001208:Asia / Q000453:epidemiology; D001858:Bone Nails / Q000706:statistics & numerical data; D005260:Female; D005594:Fracture Fixation, Intramedullary / Q000295:instrumentation* / Q000379:methods / Q000706:statistics & numerical data*; D017102:Fracture Healing; D017759:Fractures, Malunited / Q000453:epidemiology* / Q000517:prevention & control; D006620:Hip Fractures / Q000453:epidemiology* / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome