title: [Internal fixation of proximal humerus fractures].
abstract: BACKGROUND
  Intramedullary nails and angle-fixed plates have recently been used in proximal humerus fractures. Rigid implants might be associated with an increased risk of failure in osteoporotic conditions.
  
  
  METHODS
  Unstable fractures of the surgical neck were created in 24 pairs of human humeri. The biomechanical properties of four implants were analysed. These were a nail with conventional interlocking (PHN-K), a nail with spiral blade interlocking (PHN-S), the T-plate, and an internal fixator with elastic screw properties (reference). The specimens were subjected to axial loading and torque. Stiffness, plastic deformity, and load to failure were assessed.
  
  
  RESULTS
  The PHN-S was stiffer than the internal fixator. The PHN-K and T-plate were stiffer only during torque. Less subsidence was observed for the PHN-S. This implant failed at higher loads than the other implants.
  
  
  CONCLUSIONS
  The PHN-S offers biomechanical advantages in unstable fractures of the surgical neck of the humerus. Elastic implant properties, however, are disadvantageous.
authors.affiliation: Klinik und Poliklinik für Unfallchirurgie, Johannes-Gutenberg-Universität. Hessmann@unfall.klinik.uni-mainz.de
authors.forename: M H
authors.initials: MH
authors.lastname: Hessmann
authors.forename: W
authors.initials: W
authors.lastname: Sternstein
authors.forename: F
authors.initials: F
authors.lastname: Krummenauer
authors.forename: A
authors.initials: A
authors.lastname: Hofmann
authors.forename: P M
authors.initials: PM
authors.lastname: Rommens
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena; D001858:Bone Nails; D001860:Bone Plates; D003627:Data Interpretation, Statistical; D005260:Female; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000379:methods; D005594:Fracture Fixation, Intramedullary / Q000295:instrumentation / Q000379:methods; D017102:Fracture Healing; D006801:Humans; D006810:Humeral Fractures / Q000000981:diagnostic imaging / Q000601:surgery*; D016268:Internal Fixators; D011859:Radiography; D019415:Torque
vernacular_title: Osteosynthese von Oberarmkopffrakturen Einfluss des Implantatdesigns auf die biomechanische Stabilität.