title: Potential of polymethylmethacrylate cement-augmented helical proximal femoral nail antirotation blades to improve implant stability--a biomechanical investigation in human cadaveric femoral heads.
abstract: BACKGROUND
  Cement augmentation may improve fixation stability and reduce cut-out rate in the treatment of intertrochanteric hip fractures. The aim of this study was to compare the number of cycles to failure of polymethylmethacrylate (PMMA)-augmented helical blades with nonaugmented ones in human cadaveric femoral heads.
  
  
  METHODS
  Six pairs of cadaveric femoral heads were instrumented with a perforated proximal femoral nail antirotation blade. Within each pair, one blade was augmented using 3 mL of PMMA. All specimens underwent cyclic axial loading under physiologic conditions.Starting at 1,000 N, the load was monotonically increased by 0.1 N/cycle until construct failure occurred. To monitor the migration of the blade, anteroposterior radiographs were taken at 250 cycle increments. Nonparametric test statistics were done to calculate correlations and identify differences between study groups.
  
  
  RESULTS
  Inducing failure required a significantly higher number of cycles in the augmented group (p = 0.028). Bone mineral density was significantly related with the number of cycles to failure in nonaugmented specimens (p 0.001, R2 = 0.97), but not in the augmented group (p = 0.91, R2 = 0.34).
  
  
  CONCLUSIONS
  Implant augmentation with small amounts of PMMA enhances the cut-out resistance in proximal femoral fractures. Especially in osteoporotic bone, the procedure may improve patient care.
authors.affiliation: Biomedical Services, AO Research Institute, Davos, Switzerland. an.sermon@uzleuven.be
authors.forename: An
authors.initials: A
authors.lastname: Sermon
authors.forename: Vanessa
authors.initials: V
authors.lastname: Boner
authors.forename: Andreas
authors.initials: A
authors.lastname: Boger
authors.forename: Karsten
authors.initials: K
authors.lastname: Schwieger
authors.forename: Steven
authors.initials: S
authors.lastname: Boonen
authors.forename: Paul L
authors.initials: PL
authors.lastname: Broos
authors.forename: Robert G
authors.initials: RG
authors.lastname: Richards
authors.forename: Markus
authors.initials: M
authors.lastname: Windolf
mesh_terms: D000369:Aged, 80 and over; D001843:Bone Cements / Q000627:therapeutic use*; D015519:Bone Density; D001858:Bone Nails; D002102:Cadaver; D004867:Equipment Design; D005260:Female; D005270:Femur Head / Q000601:surgery*; D006620:Hip Fractures / Q000601:surgery*; D006801:Humans; D019904:Polymethyl Methacrylate / Q000627:therapeutic use*; D012307:Risk Factors; D018709:Statistics, Nonparametric
chemical_list: D001843:Bone Cements; D019904:Polymethyl Methacrylate