Mechanical Environment Differentiate New Bone Formation through Unidirectional Porous Hydroxyapatite Implanted in a Tibial Bone Defect of a Rabbit

INTRODUCTION: Porous hydroxyapatite (HAp) has been used as a bone substitute instead of autogenous bone grafts because of no donor site morbidity, fewer complications, as well as osteoconductivity. Previously, we reported a novel unidirectional porous hydroxyapatite (UDPHAp) with a porosity of 75% and a microstructure consisting of cross-sectional oval pores (diameter, 100–300 μm) that penetrate through the material [1]. UDPHAp exhibits good osteoconductivity and capillary formation implanted in the femoral intramedullary cavity in a rabbit [2, 3]. The objective of this study was to investigate the effect of mechanical loading condition on long-term bone remodeling in UDPHAp implanted into a tibial bone defect of a rabbit.