title: [Increasing bone screw anchoring in the femur head by cement administration via the implant--a biomechanical study].
abstract: OBJECTIVE
  Osteoporosis reveals a higher risk of fractures. Due to the lack of possibilities to anchor fixation elements, fracture treatment often turns out to be complicated. An experimental study served to investigate the extent to which the application of bone cement through a modified gliding screw (Dynamic Hip Screw DHS) would improve the screw anchoring in osteoporotic femoral heads.
  
  
  METHODS
  Quasi-static compressive and torsional load tests were used to assess the desired improvement of the screw anchoring. Cadaver femur pairs served to compare the cement augmentation to the uncemented contralateral control.
  
  
  RESULTS
  The improvement of the holding strength of the screw under static compressive and torsional load depended on the cement flow into the adjacent bone tissue. The filling with additional cement was only successful after having created a small hollow space at the screw tip with a special instrument. Consequently, under compression as well as torsion, the cement application yielded improvements from 17% up to several times as much.
  
  
  CONCLUSIONS
  In the application of gliding screws in osteoporotic femoral heads, the locally limited cement application through the implant has been shown to be a biomechanical possibility to improve screw fixation.
authors.affiliation: Universitätsklinik für Orthopädische Chirurgie, Bern, Schweiz.
authors.forename: A
authors.initials: A
authors.lastname: Kramer
authors.forename: M
authors.initials: M
authors.lastname: Angst
authors.forename: B
authors.initials: B
authors.lastname: Gasser
authors.forename: R
authors.initials: R
authors.lastname: Ganz
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001843:Bone Cements; D001863:Bone Screws; D004867:Equipment Design; D005260:Female; D005270:Femur Head / Q000473:pathology / Q000601:surgery; D005500:Follow-Up Studies; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D017102:Fracture Healing / Q000502:physiology; D006620:Hip Fractures / Q000473:pathology / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000473:pathology / Q000601:surgery*; D019904:Polymethyl Methacrylate / Q000008:administration & dosage*
chemical_list: D001843:Bone Cements; D019904:Polymethyl Methacrylate