ABSTRACT
<p><b>OBJECTIVE</b>To investigate the effect of tissue-engineering bone on repair of segmental bone defects.</p><p><b>METHODS</b>Segmental bone defect of 21mm was created at sheep left metatarsus, which was then implanted with tissue-engineering bone (the experimental group) and pure porous beta-TCP (the control group) respectively. The bone defect in the blank group was left without treatment. After the sheep were sacrificed at the 1st, 3rd, or 6th month postoperatively, the samples were taken and examined by radiological, histological and biomechanical methods as well as scanning electron microscopy. The sheep in the blank group were sacrificed at the 6th month postoperatively.</p><p><b>RESULTS</b>The osteoid tissue, woven bone and lamellar bone in the defect of the experimental group occurred earlier than in the control group. The new bone formed directly without through a cartilaginous intermediate in the experimental group, while the defect was repaired in a "creep substitution" way in the control group. At the 6th month, radiological and biomechanical tests revealed nearly complete repair of the bone defect of the experimental group, partial repair in the control group and non-healing in the blank group.</p><p><b>CONCLUSIONS</b>Tissue-engineering bone can repair bone defect, accelerating healing and without "creep substitution", which is a good option in repair of critical segmental bone defects. This study set up a basis for clinical applications in the future.</p>