Strains of two posterior spinal rods sites.

<p>Histogram shows means and standard deviations of strains at two posterior spinal rods for four constructs (SRR, BFFR, FRR, and ICR). No significant differences were demonstrated. The positive values implied tensile strains. The strains under FRR were significantly higher than that under all other conditions. BFFR produced a little better symmetry than ICR.