Fig. 4

Quantitative analyses using micro-CT. a Total percent bone volume to total volume (total BV/TV) (%). b Outer percent bone volume to total volume (outer BV/TV) (%). c Inner percent bone volume to total volume (inner BV/TV) (%). d Total percent bone surface to total volume (total BS/TV) (1/mm). e Outer percent bone surface to total volume (outer BS/TV) (1/mm). f Inner percent bone surface to total volume (inner BS/TV) (1/mm). The groups were as follows: commercialized PEEK cage group (Anterior Cervical Interbody Fusion Cage®, BAUI biotech, New Taipei City, Taiwan) and composite Ti alloy/PEEK cage groups including nonporous Comp_NonP composites with 40%-, 60%-, and 80%-porosity endplates (Comp_40%P, Comp_60%P, and Comp_80%P, respectively) [* p < 0.05 between PEEK and other groups; # p < 0.05 between Comp_NonP group and other porous groups; % p < 0.05 between Comp_40%P and porous groups (Comp_60%P and Comp_80%P); and p < 0.05 between Comp_60%P and Comp_80%P groups]