Cyclic loading of fractured cadaveric femurs after elastomer femoroplasty: an in vitro biomechanical study

Clin Biomech (Bristol). 2012 Oct;27(8):819-23. doi: 10.1016/j.clinbiomech.2012.05.007. Epub 2012 Jun 7.

Abstract

Background: Elastomer femoroplasty is a novel and experimental approach in the prevention of hip fracture surgery. Previously, we published the results of an in vitro cadaveric experiment in which we showed a significant reduction of fracture displacement in treated femurs. The aim of the present study was to establish the failure loads and inter-fragmentary movement of fractured, elastomer femoroplasty treated femurs during cyclic loading.

Methods: 16 cadaveric femurs were treated with elastomer femoroplasty and fractured in a simulated fall configuration. Each specimen underwent 10 cycles with a preload of 50 N, starting with a peak load of 250 N followed by 10 cycles of 500 N and continued with 500 N increments. The crosshead speed was 2 mm/s. The failure load, the number of completed cycles, and crosshead extensions were recorded.

Findings: The mean failure load was 2709 N (SD 1094). The number of completed cycles until failure was 60 (SD 22). The mean translation during maximum loading was 5.25 mm (SD 0.9). At 1500 N (two times the bodyweight of a 75 kg individual) the extension was 3.16 mm.

Interpretation: Preventive elastomer femoroplasty leads to the stabilization of the proximal femur after fracture. In a single leg stance configuration, cyclic loading with mean failure loads that well exceed the peak loads during normal gait is feasible.

MeSH terms

  • Aged
  • Biomechanical Phenomena
  • Bone Density
  • Bone Screws
  • Cadaver
  • Compressive Strength
  • Dimethylpolysiloxanes / chemistry
  • Elastomers
  • Female
  • Femoral Fractures / physiopathology*
  • Femoral Fractures / surgery
  • Femur / surgery
  • Gait
  • Hip Fractures / physiopathology*
  • Hip Fractures / surgery
  • Humans
  • In Vitro Techniques
  • Male
  • Materials Testing
  • Stress, Mechanical
  • Tensile Strength

Substances

  • Dimethylpolysiloxanes
  • Elastomers
  • baysilon