Table 1.
Endplate | Trabecular Bone | Cortical Shell | |
---|---|---|---|
Maximum Principal Strain | |||
90th Percentile (μstrain) | 836 ± 237 a,b | 600 ± 139 b | 437 ± 111 |
Risk of Initial Failurec | 0.25 ± 0.07 | 0.18 ± 0.04 | 0.13 ± 0.03 |
Minimum Principal Strain | |||
90th Percentile (μstrain) | −525 ± 126 a,b | −1085 ± 232 b | −861 ± 162 |
Risk of Initial Failurec | 0.08 ± 0.02 | 0.16 ± 0.03 | 0.12 ± 0.02 |
Data given as mean ± SD (n=22 vertebral bodies).
p < 0.0001 vs. trabecular bone
p < 0.0001 vs. cortical shell
The maximum and minimum principal strain limits (90th percentiles) were normalized by the respective yield strains (tension = 0.34%; compression = −0.69% (Bevill et al., 2009)) to determine the relative risk of initial failure. Compared to a lower number, a higher number indicates a greater relative risk of initial failure. Pairwise comparisons between each of the risks of initial failure were significantly different (p < 0.0001) except for the comparison between the risk of initial failure in the cortical shell in tension and in compression.