Method: Scaffolds were made of HA:β-TCP(15:85). The 3D Robocast printer was used to print a truss-design scaffold by printing each layer of a truss pattern in the X- and Y-plane, and building those layers in the Z-dimension. Twenty-four scaffolds were printed. Half were filled with CaS. Scaffold compression strength was determined by compression testing with a universal testing machine (Instron 5566) at a 1 mm/min loading rate. All scaffolds were loaded under wet conditions. For filled and unfilled scaffolds, 6 samples were loaded in the Z-dimension (perpendicular to the truss orientation) and 6 samples were tested in the Y-dimension (parallel to truss pattern).
Result: A two-way ANOVA was conducted using SigmaPlot. Mean compression strengths for unfilled scaffolds were 259.09N in the Z-axis and 35.57N in the Y-axis. For CaS filled scaffolds they were 789.65N in the Z-axis and 224.93N in the Y-axis. There are significant statistical differences between the CaS unfilled and filled scaffolds (F = 93.522, p < 0.001), and between scaffolds loaded in the Z-axis and Y-axis; F = 112.114; p< 0.001.
Conclusion: Scaffold orientation during surgical placement significantly affects compression strength. For maximum compression strength, scaffold layers should be stacked in columns. Compression strength is also significantly improved (3.4 times) by filling scaffolds with CaS. These findings can aid in the design of bone repair scaffolds for clinical applications.