Elastically suspending the screw holes of a locked osteosynthesis plate can dampen impact loads

J Appl Biomech. 2015 Jun;31(3):164-9. doi: 10.1123/jab.2014-0193. Epub 2015 Feb 2.

Abstract

Impact damping by elastic fixation is a principal engineering strategy to increase the durability of load-bearing structures exposed to prolonged dynamic loading. This biomechanical study evaluated axial impact damping provided by a novel dynamic locking plate. In this design, locking screw holes are elastically suspended within a silicone envelope inside the locking plate. Axial impact damping was assessed for 3 distinct fixation constructs applied to bridge a 10-mm fracture gap of a femoral diaphysis surrogate: a standard locking plate, a dynamic locking plate, and an Ilizarov ring fixator. First, the 3 fixation constructs were characterized by determining their axial stiffness. Subsequently, constructs were subjected to a range of axial impact loads to quantify damping of force transmission. Compared with standard locked plating constructs, dynamic plating constructs were 58% less stiff (P < .01) and Ilizarov constructs were 88% less stiff (P < .01). Impact damping correlated inversely with construct stiffness. Compared with standard plating, dynamic plating constructs and Ilizarov constructs dampened the transmission of impact loads by up to 48% (P < .01) and 74% (P < .01), respectively. In conclusion, lower construct stiffness correlated with superior damping of axial impact loads. Dynamic locking plates provide significantly greater impact damping compared with standard locking plates.

MeSH terms

  • Acceleration
  • Bone Plates*
  • Bone Screws*
  • Compressive Strength
  • Elastic Modulus
  • Equipment Failure Analysis
  • Fracture Fixation, Internal / instrumentation*
  • Prosthesis Design
  • Stress, Mechanical
  • Viscosity