title: Periprosthetic femoral fracture fixation: a biomechanical comparison between proximal locking screws and cables.
abstract: BACKGROUND
  The incidence of periprosthetic femoral fractures (PFF) around a stable stem is increasing. The aim of this biomechanical study was to examine how three different methods of fixation, for Vancouver type B1 PFF, alter the stiffness and strain of a construct under various configurations, in order to gain a better insight into the optimal fixation method.
  
  
  METHODS
  Three different combinations of proximal screws and Dall-Miles cables were used: (A) proximal unicortical locking screws alone; (B) proximal cables and unicortical locking screws; (C) proximal cable alone, each in combination with distal bicortical locking screws, to fix a stainless steel locking compression plate to five synthetic femora with simulated Vancouver type B1 PFFs. In one synthetic femora, there was a 10-mm fracture gap, in order to simulate a comminuted injury. The other four femora had no fracture gap, to simulate a stable injury. An axial load was applied to the constructs at varying degrees of adduction, and the overall construct stiffness and surface strain were measured.
  
  
  RESULTS
  With regards to stiffness, in both the gap and no gap models, method of fixation A was the stiffest form of fixation. The inclusion of the fracture gap reduced the stiffness of the construct quite considerably for all methods of fixation. The strain across both the femur and the plate was considerably less for method of fixation C, compared to A and B, at the locations considered in this study.
  
  
  CONCLUSIONS
  This study highlights that the inclusion of cables appears to damage the screw fixations and does not aid in construct stability. Furthermore, the degree of fracture reduction affects the whole construct stability and the bending behaviour of the fixation.
authors.affiliation: Institute of Medical and Biological Engineering, University of Leeds, Leeds, LS2 9JT, UK. simonmatthewgraham@doctors.org.uk.
authors.forename: Simon M
authors.initials: SM
authors.lastname: Graham
authors.affiliation: Institute of Medical and Biological Engineering, University of Leeds, Leeds, LS2 9JT, UK.
authors.forename: Jonathan H
authors.initials: JH
authors.lastname: Mak
authors.affiliation: School of Engineering, University of Hull, Hull, HU6 7RX, UK.
authors.forename: Mehran
authors.initials: M
authors.lastname: Moazen
authors.affiliation: Institute of Medical and Biological Engineering, University of Leeds, Leeds, LS2 9JT, UK.
authors.forename: Andreas
authors.initials: A
authors.lastname: Leonidou
authors.affiliation: Institute of Medical and Biological Engineering, University of Leeds, Leeds, LS2 9JT, UK.
authors.forename: Alison C
authors.initials: AC
authors.lastname: Jones
authors.affiliation: Institute of Medical and Biological Engineering, University of Leeds, Leeds, LS2 9JT, UK.
authors.forename: Ruth K
authors.initials: RK
authors.lastname: Wilcox
authors.affiliation: Institute of Medical and Biological Engineering, University of Leeds, Leeds, LS2 9JT, UK.|Division of Surgery, Department of Surgery and Cancer, Imperial College London, W12 0HS, London, UK.|Academic Orthopaedics and Trauma Unit, "PapaGeorgiou" General Hospital, Aristotle University Medical School, University Campus 54 124, Thessaloniki, Greece.
authors.forename: Eleftherios
authors.initials: E
authors.lastname: Tsiridis
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D001696:Biomechanical Phenomena; D001860:Bone Plates; D001863:Bone Screws; D001864:Bone Wires; D004867:Equipment Design; D005264:Femoral Fractures / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D005593:Fracture Fixation, Internal / Q000379:methods; D017102:Fracture Healing; D018460:Fractures, Comminuted / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D057068:Periprosthetic Fractures / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D011859:Radiography