title: New approaches for cement-based prophylactic augmentation of the osteoporotic proximal femur provide enhanced reinforcement as predicted by non-linear finite element simulations.
abstract: BACKGROUND
  High incidence and increased mortality related to secondary, contralateral proximal femoral fractures may justify invasive prophylactic augmentation that reinforces the osteoporotic proximal femur to reduce fracture risk. Bone cement-based approaches (femoroplasty) may deliver the required strengthening effect; however, the significant variation in the results of previous studies calls for a systematic analysis and optimization of this method. Our hypothesis was that efficient generalized augmentation strategies can be identified via computational optimization.
  
  
  METHODS
  This study investigated, by means of finite element analysis, the effect of cement location and volume on the biomechanical properties of fifteen proximal femora in sideways fall. Novel cement cloud locations were developed using the principles of bone remodeling and compared to the "single central" location that was previously reported to be optimal.
  
  
  RESULTS
  The new augmentation strategies provided significantly greater biomechanical benefits compared to the "single central" cement location. Augmenting with approximately 12ml of cement in the newly identified location achieved increases of 11% in stiffness, 64% in yield force, 156% in yield energy and 59% in maximum force, on average, compared to the non-augmented state. The weaker bones experienced a greater biomechanical benefit from augmentation than stronger bones. The effect of cement volume on the biomechanical properties was approximately linear. Results of the "single central" model showed good agreement with previous experimental studies.
  
  
  CONCLUSIONS
  These findings indicate enhanced potential of cement-based prophylactic augmentation using the newly developed cementing strategy. Future studies should determine the required level of strengthening and confirm these numerical results experimentally.
authors.affiliation: AO Research Institute Davos, Switzerland. Electronic address: peter.varga@aofoundation.org.
authors.forename: Peter
authors.initials: P
authors.lastname: Varga
authors.affiliation: AO Research Institute Davos, Switzerland.
authors.forename: Jason A
authors.initials: JA
authors.lastname: Inzana
authors.affiliation: Institute of Surgical Technology and Biomechanics, University of Bern, Switzerland.
authors.forename: Jakob
authors.initials: J
authors.lastname: Schwiedrzik
authors.affiliation: Institute of Surgical Technology and Biomechanics, University of Bern, Switzerland.
authors.forename: Philippe K
authors.initials: PK
authors.lastname: Zysset
authors.affiliation: AO Research Institute Davos, Switzerland.
authors.forename: Boyko
authors.initials: B
authors.lastname: Gueorguiev
authors.affiliation: Department for Trauma Surgery, Medical University Innsbruck, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Blauth
authors.affiliation: AO Research Institute Davos, Switzerland.
authors.forename: Markus
authors.initials: M
authors.lastname: Windolf
mesh_terms: D000058:Accidental Falls; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D001843:Bone Cements / Q000627:therapeutic use*; D002102:Cadaver; D005260:Female; D005264:Femoral Fractures / Q000517:prevention & control*; D005270:Femur Head / Q000000981:diagnostic imaging / Q000187:drug effects*; D020342:Finite Element Analysis; D006801:Humans; D008297:Male; D010024:Osteoporosis / Q000150:complications*; D014057:Tomography, X-Ray Computed
chemical_list: D001843:Bone Cements
keywords: Femoroplasty; Finite element analysis; Osteoporosis; Prophylactic augmentation; Proximal femur