BACKGROUND:With the wide application of bone repair scaffold in the field of medicine, nano-hydroxyapatite (nHA) and silk fibroin (SF) both of which have good biological properties have become research hotspots in recent years.OBJECTIVE:To study the feasibility of nHA/SF composite materials loaded with recombinant human bone morphogenetic protein 2 (rhBMP-2) to restore the initial stability of the spinal segment in rabbits.METHODS: Thirty-six male health New Zealand rabbits were randomly divided into three groups, followed by preparation of spinal instability models. Autogenous iliac bone, nHA/SF composite, and rhBMP-2/nHA/SF composite were implanted into the L4/5 spinal segment in autologous bone group, nHA/SF group and rhBMP-2/nHA/SF group, respectively. X-ray exmaination was performed at 12 weeks postoperatively, and then the animals were killed for gross observation. The stability of the fusion segments was tested through a tensile machine. Histologically, bone graft fusion at the surgical site was observed.RESULTS AND CONCLUSION:(1) Findings from the gross specimen observation showed that the specimens at the fusion site presented with a hard texture. Obvious signs of fusion were visible in the autologous bone group, followed by the rhBMP-2/nHA/SF group, while no signs of fusion were detected in the nHA/SF group. (2) At 12 weeks postoperatively, a large number of trabecular bones grew into the boundary between the vertebral body and the iliac crest graft block in the autologous bone group. A little trabecular bone was found in the boundary in the nHA/SF group, while a lot of trabecular bone tissues were found in the boundary in the rhBMP-2/nHA/SF group. In accordance with the standard of fusion, there were 10, 3, and 9 rats in the autologous bone, nHA/SF and rhBMP-2/nHA/SF groups, respectively. (3) The range of motion of the spine in the rhBMP-2/nHA/SF showed no statistical difference from that in the autologous bone group, but was significantly higher than that in the nHA/SF group (P < 0.05). (4) Osseous connection was found around the bone graft in the autologous bone and nHA/SF groups, but no mature bone tissue was visible in the latter group. In the rhBMP-2/nHA/SF group, a large number of new capillaries was found and permeated into the spinal tissues. In summary, nHA/SF composite materials loaded with rhBMP-2 possess good biocompatibility, mechanical properties and bone induction ability, which can rebuild the initial stability of the spine in a short time.