title: Is Disuse Osteopenia a Favorable Prognostic Sign After Femoral Neck Fracture?
abstract: OBJECTIVE
  Avascular necrosis (AVN) of the femoral head is a devastating complication following fixation of femoral neck fractures in younger adults. In this study, we investigate the prognostic utility of disuse osteopenia.
  
  
  METHODS
  Retrospective study.
  
  
  METHODS
  Three academic Level 1 trauma centers.
  
  
  METHODS
  One hundred twenty patients younger than 60 years treated for a femoral neck fracture.
  
  
  METHODS
  N/A.
  
  
  METHODS
  The presence of sclerosis or osteopenia, compared to the contralateral femoral head, was measured 6 weeks from injury both subjectively and using a novel radiographic measure, the relative density ratio (RDR). The outcome measure was radiographic development of AVN.
  
  
  RESULTS
  The presence of relative sclerosis was associated with AVN and overall treatment failure. Patients with subjective relative sclerosis had a 12.6 (95% confidence interval, 2.9-61.3; P < 0.001) times higher odds of developing AVN. Multiple logistic regression showed that for every 0.10 increase in the RDR, there was a 5.2 increase in the odds (95% confidence interval, 2.1-26.9; P = 0.009) of developing AVN. Patients with an RDR of ≥1.2 have an 80% probability of AVN, whereas those with an RDR ≤0.8 have a <1% probability of developing AVN.
  
  
  CONCLUSIONS
  Disuse osteopenia detected on 6-week radiographs is a favorable prognostic sign following fixation of femoral neck fractures. Patients who have relative sclerosis of the femoral head at 6-week follow-up are at a higher risk of developing AVN.
  
  
  METHODS
  Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.
authors.affiliation: *Department of Orthopedic Surgery, Harvard Medical School Orthopedic Trauma Initiative, Brigham and Women's Hospital, Boston, MA; †Department of Orthopaedic Surgery, Harvard Medical School Orthopedic Trauma Initiative, Massachusetts General Hospital, Boston, MA; and ‡Department of Orthopedics, Harvard Medical School Orthopedic Trauma Initiative, Beth Israel Deaconess Medical Center, Boston, MA.
authors.forename: Beverlie L
authors.initials: BL
authors.lastname: Ting
authors.forename: Marilyn
authors.initials: M
authors.lastname: Heng
authors.forename: Mark S
authors.initials: MS
authors.lastname: Vrahas
authors.forename: Edward K
authors.initials: EK
authors.lastname: Rodriguez
authors.forename: Mitchel B
authors.initials: MB
authors.lastname: Harris
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Weaver
mesh_terms: D000293:Adolescent; D000328:Adult; D001851:Bone Diseases, Metabolic / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D001900:Boston / Q000453:epidemiology; D015984:Causality; D015897:Comorbidity; D005260:Female; D005265:Femoral Neck Fractures / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000601:surgery*; D005271:Femur Head Necrosis / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000517:prevention & control; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods*; D011379:Prognosis; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012307:Risk Factors; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D055815:Young Adult