Personalizing β-TCP porous scaffolds to promote osteogenesis: a study of segmental femoral defects in beagle models

The increasing clinical occurrence of segmental bone defects is demanding constant improvements in bone transplantation to overcome issues of limited resources, immune rejection and poor structural complement. This study aimed to develop a personalized bone defect repair modality using 3D-printed tricalcium phosphate (<i>β</i>-TCP) grafts and to assess its osteogenic impacts in a femoral segmental defect model in beagles, as a basis for clinical studies and application. A<i>β</i>-TCP scaffold was designed and manufactured using computer-aided design. A 3 cm segmental bone defect model was established in 27 one-year-old male beagles, and were randomly divided into three groups. The control group utilizing only intramedullary fixation, the autograft group with an added autologous bone graft and<i>β</i>-TCP group using a<i>β</i>-TCP scaffold. The study animals were monitored for 24 weeks postoperative and assessed for vital signs, imaging, and histological indicators periodically. All of the Beagles underwent successful modeling and experimentation, and were fully ambulatory at four weeks. Postoperative x-rays showed no evidence of loosening or displacement of the intramedullary nails. Micro-CT and histological staining indicated Osteogenesis starting from the fourth week, with the most significant growth seen using autografts (<i>P</i>< 0.05). New bone (NB) formation is seen adhering to the surface and proximal femur after osteotomy. The<i>β</i>-TCP group had significantly more evidence of Osteogenesis when compared to the control group (<i>P</i>< 0.05), characterized by NB visible throughout the porous structure and distal residual femur. The control group showed bone formation impeded by fibrosis, showing poor bone growth mainly around the distal end after osteotomy, with poor overall repair outcomes.<i>Conclusion.</i>Growth factor-deficient<i>β</i>-TCP porous scaffolds demonstrated promising Osteoinductive properties in repairing large segment bone defects in Beagles' femurs. It effectively promoted bone growth and is structurally advantageous for weight bearing long bones.