Differences in bone volume and bone volume accumulation rate by in vivo microCT at weeks 4, 8, and 12 were determined by two-way analysis of variance (ANOVA) with Tukey’s post hoc test. Defect bridging was determined by χ2 test for trend in each group; comparisons between groups were assessed with individual χ2 tests and Bonferroni correction for multiple comparisons. Ex vivo microCT bone volume, bone volume fraction, and 3D morphometry were assessed by one- or two-way ANOVA with interaction and Tukey’s post hoc test. Biomechanical properties were analyzed by two-way ANOVA with interaction and Tukey’s post hoc test. Mechanical property regressions were performed using an exhaustive best subset algorithm to determine the best predictors of maximum torque and torsional stiffness from a subset of morphologic parameters measured, including minimum or mean pMOI (Jmin or Jmean), bone volume fraction, binary bridging score (yes or no), trabecular thickness, trabecular separation, trabecular number, degree of anisotropy, and connectivity density based on AIC (51). The lowest AIC selects the best model while giving preference to models with less parameters. Last, the overall best model for each predicted mechanical property was compared to its measured value using type II general linear regression. All data are shown as means ± SD, some with individual data points or as box plots showing median as horizontal line, mean as “+,” and 25th and 75th percentiles as boxes with whiskers at minimum and maximum values, respectively. Fold changes in mRNA expression and ratios of phosphorylated SMADs/total SMADs were analyzed by one-way ANOVA with Tukey’s multiple comparison post hoc test. The significance level was set at P < 0.05 or lower. Groups with shared letters have no significant differences. GraphPad Prism software v6.0 (GraphPad Software, La Jolla, CA) was used for all analyses.