title: Low bone mineral density is not related to failure in femoral neck fracture patients treated with internal fixation.
abstract: OBJECTIVE
  Internal fixation (IF) in femoral neck fractures has high reoperation rates and some predictors of failure are known, such as age, quality of reduction, and implant positioning. Finding new predictors of failure is an ongoing process, and in this study we evaluated the importance of low bone mineral density (BMD).
  
  
  METHODS
  140 consecutive patients (105 females, median age 80) treated with IF had a dual-energy X-ray absorptiometry (DXA) scan of the hip performed median 80 days after treatment. The patients' radiographs were evaluated for fracture displacement, implant positioning, and quality of reduction. From a questionnaire completed during admission, 2 variables for comorbidity and walking disability were chosen. Primary outcome was low hip BMD (amount of mineral matter per square centimeter of hip bone) compared to hip failure (resection, arthroplasty, or new hip fracture). A stratified Cox regression model on fracture displacement was applied and adjusted for age, sex, quality of reduction, implant positioning, comorbidity, and walking disability.
  
  
  RESULTS
  49 patients had a T-score below -2.5 (standard deviation from the young normal reference mean) and 70 patients had a failure. The failure rate after 2 years was 22% (95% CI: 12-39) for the undisplaced fractures and 66% (CI: 56-76) for the displaced fractures. Cox regression showed no association between low hip BMD and failure. For the covariates, only implant positioning showed an association with failure.
  
  
  CONCLUSIONS
  We found no statistically significant association between low hip BMD and fixation failure in femoral neck fracture patients treated with IF.
authors.affiliation: Department of Orthopaedic Surgery and Traumatology.
authors.forename: Bjarke
authors.initials: B
authors.lastname: Viberg
authors.forename: Jesper
authors.initials: J
authors.lastname: Ryg
authors.forename: Søren
authors.initials: S
authors.lastname: Overgaard
authors.forename: Jens
authors.initials: J
authors.lastname: Lauritsen
authors.forename: Ole
authors.initials: O
authors.lastname: Ovesen
mesh_terms: D015502:Absorptiometry, Photon; D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density / Q000502:physiology; D005260:Female; D005265:Femoral Neck Fractures / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D005593:Fracture Fixation, Internal / Q000009:adverse effects*; D017102:Fracture Healing / Q000502:physiology; D006621:Hip Joint / Q000000981:diagnostic imaging; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D010024:Osteoporosis / Q000150:complications* / Q000503:physiopathology; D058866:Osteoporotic Fractures / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D012086:Reoperation; D012189:Retrospective Studies; D012307:Risk Factors; D017211:Treatment Failure