Biomechanical evaluation of the rabbit tibia after implantation of porous hydroxyapatite/collagen in a rabbit model.

Abstract

Porous hydroxyapatite/collagen composite (HAp/Col) is an artificial bone substitute with excellent osteoconduction and sponge-like elasticity. However, the porosity of porous HAp/Col is as high as 95% and its mechanical strength is very poor. The aim of this study was to biomechanically analyze sites implanted with porous HAp/Col. Rectangular cortical bone defects (3 × 8 mm) were made in the tibia of rabbits and filled with porous HAp/Col or porous β-tricalcium phosphate or left vacant. The tibia was harvested at 4 or 12 weeks after surgery. The harvested specimens were analyzed using a micro-CT system, and the mechanical strength of the specimens was examined by torsion testing. Quantitative micro-CT analysis of the regenerated bone revealed that both bone substitutes equally facilitated bone regeneration. Biomechanical testing demonstrated that the torsional strength of HAp/Col-implanted sites was higher than that of the control (vs control: p = 0.030 and vs β-TCP: p = 0.056). The results indicate that porous HAp/Col implantation is an effective strategy for recovery of the mechanical strength of bone defects.