Fig. 4　Rates of posterolateral lumbar fusion volume increases. Rates of fusion volume increases were calculated at 2-week intervals for 8 weeks post-surgery. Data are presented as mean ± SD (n = 6 rats per group) . Statistical analysis was performed using repeated measures ANOVA followed by Tukey’s post-hoc test. Main effect of treatment: F (3, 20) = 1118.68, p < 0.001; Main effect of time: F (3, 60) = 788.95, p < 0.001; Interaction: F (9, 60) = 231.81, p < 0.001. *p < 0.05 vs. control group at each time point.