title: Proximal humeral fracture fixation: locking plate construct ± intramedullary fibular allograft.
abstract: BACKGROUND
  Locking plate constructs for proximal humeral fractures can fail due to varus collapse, especially in osteoporotic bone with medial cortex comminution. Augmentation, using a fibular allograft as an intramedullary bone peg, may strengthen fixation preventing varus collapse. This study investigated the ability of the augmented locking plate construct to withstand repetitive varus stresses relative to the nonaugmented construct.
  
  
  METHODS
  Proximal humeral fractures with medial comminution were simulated by performing wedge-shaped osteotomies at the surgical neck in cadaveric specimens. For each cadaver (n = 8), 1 humeral fracture was fixated with the locking plate construct alone and the other with the locking plate construct plus ipsilateral fibular autograft augmentation. The humeral head was immobilized and a repetitive, medially directed load was applied to the humeral shaft until construct collapse or until 25000 cycles were completed.
  
  
  RESULTS
  No augmented construct collapsed. In comparison, 6 of 8 nonaugmented constructs collapsed (P < .05). Collapse in the 6 nonaugmented constructs occurred after an average ±SD of 6604 ± 1984 cycles. Screw penetration of the articular surface was found in only 1 of the nonaugmented constructs.
  
  
  CONCLUSIONS
  Fibular allograft augmentation increased the ability of the locking plate to withstand repetitive varus loading. Clinically, this may assist proximal humeral fracture fixation in osteoporotic bone with medial cortex comminution.
authors.affiliation: Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Roxanne M
authors.initials: RM
authors.lastname: Chow
authors.forename: Farhana
authors.initials: F
authors.lastname: Begum
authors.forename: Lauren A
authors.initials: LA
authors.lastname: Beaupre
authors.forename: Jason P
authors.initials: JP
authors.lastname: Carey
authors.forename: Samer
authors.initials: S
authors.lastname: Adeeb
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Bouliane
mesh_terms: D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D001860:Bone Plates; D002102:Cadaver; D019245:Compressive Strength; D019544:Equipment Failure Analysis; D005260:Female; D005360:Fibula / Q000601:surgery / Q000637:transplantation*; D005593:Fracture Fixation, Internal / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D008297:Male; D012680:Sensitivity and Specificity; D012784:Shoulder Fractures / Q000601:surgery*; D012785:Shoulder Joint / Q000601:surgery; D013314:Stress, Mechanical; D014184:Transplantation, Homologous