title: Do Transcortical Screws in a Locking Plate Construct Improve the Stiffness in the Fixation of Vancouver B1 Periprosthetic Femur Fractures? A Biomechanical Analysis of 2 Different Plating Constructs.
abstract: OBJECTIVE
  This biomechanical study compared Vancouver B1 periprosthetic femur fractures fixed with either a locking plate and anterior allograft strut construct or an equivalent locking plate with locking attachment plates construct in paired cadaveric specimens.
  
  
  METHODS
  After 9 pairs of cadaveric femora were implanted with a cemented primary total hip arthroplasty, an oblique osteotomy was created distal to the cement mantle. Femora underwent fixation with either: (1) a locking plate with anterior strut allograft (locking compression plating (LCP)-Allograft) or (2) a locking plate with 2 locking attachment plates (LAPs) (LCP-LAP). Construct stiffness was compared in nondestructive mechanical testing for 2 modes of compression (20 degrees abduction and 20 degrees flexion), 2 four-point bending directions (anterior-posterior and medial-lateral), and torsion. A final load to failure test evaluated the axial compression required to achieve fracture gap closure or construct yield. Fixation was compared through paired t tests (α = 0.05).
  
  
  RESULTS
  The LCP-Allograft construct demonstrated higher stiffness values in compressive abduction (207 ± 57 vs.151 ± 40 N/mm), torsion (1666 ± 445 vs. 1125 ± 160 N mm/degree) and medial-lateral four-point bending (413 ± 135 vs. 167 ± 68 N/mm) compared with the LCP-LAP construct (P < 0.05). No differences were identified between the 2 constructs in compressive flexion, anterior-posterior bending, or the load to failure test (P > 0.05).
  
  
  CONCLUSIONS
  Use of the anterior allograft strut created a stiffer construct compared with the LCP-LAP for the treatment of a Vancouver B1 periprosthetic femur fracture only in loading modes with increased medial-lateral bending. Although these static load results are indicative of the early postoperative environment, further fatigue testing is required to better understand the importance of the reduced medial-lateral stiffness over a longer period.
authors.affiliation: *Division of Orthopaedic Surgery, Sunnybrook Health Sciences Centre, University of Toronto, ON, Canada; and†Orthopaedic Biomechanics Laboratory, Sunnybrook Research Institute, Toronto, ON, Canada.
authors.forename: Jasjit
authors.initials: J
authors.lastname: Lochab
authors.forename: Andrew
authors.initials: A
authors.lastname: Carrothers
authors.forename: Edwin
authors.initials: E
authors.lastname: Wong
authors.forename: Stewart
authors.initials: S
authors.lastname: McLachlin
authors.forename: Wassim
authors.initials: W
authors.lastname: Aldebeyan
authors.forename: Richard
authors.initials: R
authors.lastname: Jenkinson
authors.forename: Cari
authors.initials: C
authors.lastname: Whyne
authors.forename: Markku T
authors.initials: MT
authors.lastname: Nousiainen
mesh_terms: D000368:Aged; D001860:Bone Plates; D001863:Bone Screws; D002102:Cadaver; D019245:Compressive Strength; D003198:Computer Simulation; D055119:Elastic Modulus; D005260:Female; D005264:Femoral Fractures / Q000503:physiopathology* / Q000601:surgery*; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000379:methods; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D057068:Periprosthetic Fractures / Q000503:physiopathology* / Q000601:surgery*; D012086:Reoperation / Q000295:instrumentation / Q000379:methods; D013314:Stress, Mechanical; D013718:Tensile Strength; D016896:Treatment Outcome