Table I.
Regression parameters (slope and intercept), correlation coefficients (R2), and p-values of linear regressions between experimentally measured pull-out strength and bone volume fraction around the screws, as well as with the predicted pull-out stiffness from the region of interest and full vertebra models.
| Screw | BV/TV | µFE ROI pull-out stiffness | µFE FV pull-out stiffness | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Slope | Intercept | R2 | p-value* | Slope | Intercept | R2 | p-value* | Slope | Intercept | R2 | p-value* | |
| L | 7,964.6 | -1,699.6 | 0.8941 | 0.054 | 5.4589 | -762.37 | 0.9165 | 0.020 | 1.0566 | -335.55 | 0.9556 | 0.0124 |
| R | 4,781 | -622.65 | 0.7485 | 0.135 | 5.4678 | -778.6 | 0.9769 | 0.042 | 0.8892 | -144.8 | 0.9177 | 0.040 |
| L + R | 6,133.8 | -1,064.8 | 0.7884 | 0.003 | 5.4697 | -772.75 | 0.94 | 9.03E-05 | 0.9845 | -251.64 | 0.9344 | 6.4E-05 |
*
Linear regression correlation.
BV/TV, bone volume fraction; µFE, micro-finite element; FV, full vertebra; L, Ennovate screw; R, S4 screw; ROI, region of interest.