title: Biomechanical investigation of an alternative concept to angular stable plating using conventional fixation hardware.
abstract: BACKGROUND
  Angle-stable locking plates have improved the surgical management of fractures. However, locking implants are costly and removal can be difficult. The aim of this in vitro study was to evaluate the biomechanical performance of a newly proposed crossed-screw concept ("Fence") utilizing conventional (non-locked) implants in comparison to conventional LC-DCP (limited contact dynamic compression plate) and LCP (locking compression plate) stabilization, in a human cadaveric diaphyseal gap model.
  
  
  METHODS
  In eight pairs of human cadaveric femora, one femur per pair was randomly assigned to receive a Fence construct with either elevated or non-elevated plate, while the contralateral femur received either an LCP or LC-DCP instrumentation. Fracture gap motion and fatigue performance under cyclic loading was evaluated successively in axial compression and in torsion. Results were statistically compared in a pairwise setting.
  
  
  RESULTS
  The elevated Fence constructs allowed significantly higher gap motion compared to the LCP instrumentations (axial compression: p <or= 0.011, torsion p <or= 0.015) but revealed similar performance under cyclic loading (p = 0.43). The Fence instrumentation with established bone-plate contact revealed larger fracture gap motion under axial compression compared to the conventional LC-DCP osteosynthesis (p <or= 0.017). However, all contact Fence specimens survived the cyclic test, whereas all LC-DCP constructs failed early during torsion testing (p < 0.001). All failures occurred due to breakage of the screw heads.
  
  
  CONCLUSIONS
  Even though accentuated fracture gap motion became obvious, the "Fence" technique is considered an alternative to cost-intensive locking-head devices. The concept can be of interest in cases were angle-stable implants are unavailable and can lead to new strategies in implant design.
authors.affiliation: AO Research Institute Davos, AO Foundation, Clavadelerstrasse 8, Davos, Switzerland. markus.windolf@aofoundation.org
authors.forename: Markus
authors.initials: M
authors.lastname: Windolf
authors.forename: Kajetan
authors.initials: K
authors.lastname: Klos
authors.forename: Dirk
authors.initials: D
authors.lastname: Wähnert
authors.forename: Bas
authors.initials: B
authors.lastname: van der Pol
authors.forename: Roman
authors.initials: R
authors.lastname: Radtke
authors.forename: Karsten
authors.initials: K
authors.lastname: Schwieger
authors.forename: Roland P
authors.initials: RP
authors.lastname: Jakob
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D001860:Bone Plates / Q000592:standards / Q000639:trends*; D001863:Bone Screws / Q000592:standards / Q000639:trends*; D002102:Cadaver; D019245:Compressive Strength / Q000502:physiology; D018483:Diaphyses / Q000033:anatomy & histology / Q000502:physiology / Q000601:surgery; D004867:Equipment Design / Q000379:methods*; D004868:Equipment Failure; D019544:Equipment Failure Analysis / Q000379:methods; D005260:Female; D005269:Femur / Q000033:anatomy & histology / Q000502:physiology / Q000601:surgery; D005592:Fracture Fixation / Q000295:instrumentation* / Q000379:methods; D050723:Fractures, Bone / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013314:Stress, Mechanical; D016474:Weight-Bearing / Q000502:physiology