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Updated: Jul 12, 2025
Establishment of a Segmental Femoral Critical-size Defect Model in Mice Stabilized by Plate Osteosynthesis
Published on: October 12, 2016
Plate fixation optimization for distal femoral fractures with segmental bone loss: Defining the preferred screw
Deniz U Erbulut1, Nicholas Green2, Caroline Grant3
1Herston Biofabrication Institute, Metro North Hospital and Health Service, Brisbane, QLD, 4029, Australia; Department of Orthopaedic Surgery, The Royal Brisbane and Women's Hospital, Brisbane, QLD, Australia; School of Mechanical and Mining engineering, University of Queensland, Saint Lucia, QLD, Australia.
Objectives:
Distal femur fractures can exhibit extensive comminution, and open fractures may result in bone loss. These injuries are under high mechanical demands when stabilized with a lateral locked plate (LLP), and are at risk of non-union or implant failure. This study investigates the optimal LLP screw configuration for distal femur fractures with a large metadiaphyseal gap of 5 cm.
Methods:
A finite element (FE) model, validated against experimentally measured strains and displacement, evaluated pull-out forces and stress concentration on typical implants under clinical conditions corresponding with the 10 % point during the stance phase of the gait cycle.
Results:
Maximum stress was up to 83 % less when the ratio (Cp) between the proximal screw-distribution-length and the distance of the first screw to the fracture was less than 0.2; maximum pull-out force was 99 % less when this ratio was higher than 0.4.
Conclusions:
Screw configuration based on either normal or osteopenic bone quality plays an important role in determining the risk of construct failure for a major (50 mm) distal femoral metadiaphyseal segmental defect. This study provides valuable information when planning definitive fixation for distal femur fractures with extensive comminution or segmental bone defects, to mitigate the risk of implant failure and subsequent nonunion.
