Biomechanical evaluation of mini-fragment hardware for supination external rotation fractures of the distal fibula

Foot Ankle Spec. 2013 Apr;6(2):88-93. doi: 10.1177/1938640013477130. Epub 2013 Feb 25.

Abstract

Background: Supination external rotation distal fibula fractures are common, requiring fixation when associated with talar displacement. Subcutaneous distal fibula hardware may become painful, necessitating operative removal. We hypothesize that mini-fragment and small-fragment constructs will demonstrate similar biomechanical stability.

Methods: A biomechanical comparison was performed in synthetic osteoporotic sawbones. The first arm compared two 2.4-mm lag screws with one 3.5-mm lag screw for fixation of a simulated supination external rotation distal fibula fracture. The second arm compared a 2.4-mm plate-screw construct with a 3.5-mm lag screw and one-third tubular neutralization plate. During torsional testing, torque and displacement were recorded, and stiffness and peak torque were determined.

Results: Differences in mean stiffness and mean load at failure were not statistically significant with lag screw-only fixation. The 3.5-mm plate-screw construct outperformed the 2.4-mm plate-screw construct, but neither mean stiffness nor mean load at failure were statistically significantly different. Dynamic testing also demonstrated similar results.

Conclusion: Our data suggest that isolated 2.4-mm screws function similarly to one 3.5-mm screw. Although the 3.5-mm plate-screw construct was stiffer, mean load at failure was equivalent for the 2 constructs. These data provide biomechanical evidence to support further investigation in the use of mini-fragment hardware for distal fibula fracture fixation.

Levels of evidence: Therapeutic, Level V.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biomechanical Phenomena
  • Bone Plates*
  • Bone Screws*
  • Equipment Design
  • Fibula / injuries*
  • Fracture Fixation, Internal / instrumentation*
  • Humans
  • Models, Biological*
  • Osteoporotic Fractures / physiopathology*
  • Osteoporotic Fractures / surgery
  • Supination / physiology*