## 3 Results
### Bone Formation and Scaffold Degradation
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Data by Time Point:** & \multicolumn{2}{c}{**8-Week Groups (\(n=10\))**} & \multicolumn{2}{c}{**13-Week Groups (\(n=10\))**} \\ \hline Average TNC/mL & \multicolumn{2}{c}{\(3.23\times 10^{7}\) \(\leq 5.44\times 10^{6}\)} & \multicolumn{2}{c}{\(3.18\times 10^{7}\) \(\leq 3.41\times 10^{6}\)} \\ Average CFU-F/mL & \multicolumn{2}{c}{\(2486\pm 933\)} & \multicolumn{2}{c}{\(2935\pm 488\)} \\ \hline  & Porous & Non-porous & \(p\)-value & Porous & Non-porous & \(p\)-value \\ Residual Scaffold Vol. (mm\({}^{3}\)) & 22.62 & 54.11 & \textless{}0.001 & 14.59 & 42.50 & \textless{}0.001 \\ Bone Vol. (BV) (mm\({}^{3}\)) & 22.25 & 15.87 & 0.009 & 29.63 & 16.16 & \textless{}0.001 \\ Bone Vol./Total Vol. & 0.23 & 0.16 & 0.009 & 0.31 & 0.17 & \textless{}0.001 \\ Connectivity Density (1/mm\({}^{3}\)) & 28.45 & 8.73 & \textless{}0.001 & 40.40 & 12.84 & \textless{}0.001 \\ Trabecular Thickness (mm) & 0.18 & 0.15 & 0.004 & 0.19 & 0.15 & \textless{}0.001 \\ Bone Surface Area (mm\({}^{2}\)) & 446.02 & 410.81 & 0.384 & 576.81 & 442.76 & 0.003 \\ Mean Bone Density (mgH\({}^{1}\)/cm\({}^{3}\)) & 730.84 & 615.17 & \textless{}0.001 & 771.76 & 644.94 & \textless{}0.001 \\ \hline
**Data by Scaffold Type:** & \multicolumn{2}{c}{**Porous HA (\(n=10\))**} & \multicolumn{2}{c}{**Non-porous HA (\(n=10\))**} \\ \hline  & 8 weeks & 13 weeks & \(p\)-value & 8 weeks & 13 weeks & \(p\)-value \\ Residual Scaffold Vol. (mm\({}^{3}\)) & 22.62 & 14.59 & 0.014 & 54.11 & 42.50 & 0.049 \\ Bone Vol. (BV) (mm\({}^{3}\)) & 22.25 & 29.63 & 0.003 & 15.87 & 16.16 & 0.901 \\ Bone Vol./Total Vol. & 0.23 & 0.31 & 0.003 & 0.16 & 0.17 & 0.899 \\ Connectivity Density (1/mm\({}^{3}\)) & 28.45 & 40.40 & 0.010 & 8.73 & 12.84 & 0.078 \\ Trabecular Thickness (mm) & 0.18 & 0.19 & 0.207 & 0.15 & 0.15 & 0.884 \\ Bone Surface Area (mm\({}^{2}\)) & 446.02 & 576.81 & 0.003 & 410.81 & 442.76 & 0.447 \\ Mean Bone Density (mgH\({}^{1}\)/cm\({}^{3}\)) & 730.84 & 771.76 & 0.016 & 615.17 & 644.94 & 0.027 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Average total nucleated cell (TNC) and colony-forming unit-fibroblast (CFU-F) concentrations, and scaffold and bone characterization by MicroCT for porous and non-porous hydroxyapatite implants at 8- and 13-week harvest time points (\(n=10\) per material per time point). Figure 4: **(A)** Average bone regeneration versus time for porous (black) and non-porous (gray) hydroxyapatite (HA) granules through 13 weeks in vivo, with significant differences at both time points (\(p<0.01\)) and improvement with porous HA between 8 and 13 weeks (\(p>0.005\)); (**B**) new bone and remaining scaffold volume at 8 and 13 weeks for each material with significant decreases in residual scaffold for all scaffolds (\(p<0.05\)). New bone volume regenerated by porous and non-porous HA and corresponding colony forming units-fibroblast (CFU-F or MSC) concentration by rabbits at 8 (**C**) and 13 weeks (**D**) indicates improved function of non-porous scaffolds with increasing CFU-F/mL. Figure 3: Representative MicroCT images at 8 weeks post-implantation of autologous bone marrow aspirate with non-porous (**A**) or porous (**B**) HA microparticles. Similar images taken at 13 weeks post-implantation for non-porous (**C**) and porous (**D**) HA microparticles. New bone formation (purple) and residual scaffold material (white, light gray) were calculated as a total volume and percentage of the original defect volume.