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Objective To investigate the effect of hydroxyapatite/zirconia (HA/ZrO2) scaffold by three-dimensional printing compounded with vascular endothelial growth factor (VEGF) 165 calcium alginate microsphere slow-release system on repairing femoral shaft defects in dogs.Methods The HA/ZrO2 artificial prosthesis was prepared by three-dimensional printing,and the co-culture system of slow-release system of composite VEGF 165 calcium alginate microspheres was constructed.Sixteen beagle dogs were divided into four groups according to the extent of femoral shaft interception,with four dogs in each group.Group A:no biomaterials were implanted into the middle femur of dogs after 15 mm of femur interception as blank control group;Group B:HA/ZrO2 scaffolds composite with VEGF165 calcium alginate microspheres were implanted into the middle femur of dogs after 15 mm of femur interception;Group C:the same method as Group B was adopted after 25 mm of femur interception;Group D:the same method as Group B was adopted after 35 mm of femur interception.General examination and X-ray imaging observation were taken after operation.The ability of new HA/ZrO2 gradient biocomposites to repair bone defects was evaluated by micro CT scanning,biomechanical testing,ink staining and toluidine blue staining 12 weeks after operation.Results The drug loading capacity of calcium alginate microspheres reached (23.6 ± 2.9) ng/mg,and the entrapment efficiency reached (62.4 ± 3.6) ％,showing a slow rate of release.Gross examination showed surgical incision was healed in all four groups.Postoperative X-ray imaging of experimental animals showed that nonunion was formed in Group A over time;in Group B,the artificial prosthesis was gradually filled with new bone and the boundary was blurred;in Group C,the early reaction was slower than that in Group A,and the callus passed continuously 12 weeks after operation;in Group D,new bone formation was slow,only surrounding the broken end.At 12 weeks after operation,the neonatal bone mass was (238.6 ± 19.1)mm3 in Group B,(223.3 ± 13.4) mm3 in Group C,and (110.8 ± 6.5) mm3 in Group D.There were significant differences among the three groups (P ＜ 0.05),but no significant difference was found between Group B and Group C (P ＞ 0.05).The results limit compression test at 12 weeks after operation showed no significant differences among Groups B [(49.7 ± 2.3) MPa],C [(49.81 ± 2.4) MPa] and D [(46.9 ± 3.6) MPa](P ＞ 0.05).At 12 weeks after operation,the histological sections showed that the blood vessels in Groups B and C were thickened,with obvious branches,and the surrounding new bone increased.During the period,the blood vessels were filled with vascular network.There were no obvious differences in the number and shape of blood vessels between groups.However,Group B had more new bones and blood vessel networks.New bone and small vascular networks were seen in Group D.Conclusion The hydroxyapatite/zirconia scaffold by three-dimensional printing compounded with vascular endothelial growth factor 165 calcium alginate microsphere slow-release system can repair dogs' femoral bone defect within 35 mm.
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BACKGROUND:Porous gradient hydroxyapatite/zirconia composite, which can adhere to a variety of cel s, such as osteoblasts, bone marrow mesenchymal stem cel s and chondrocytes, can induce and promote fracture healing or replace bone defects. OBJECTIVE:To review the development and application of porous gradient hydroxyapatite/zirconia composite in bone tissue engineering. METHODS:Articles related to porous gradient hydroxyapatite/zirconia composite in bone tissue engineering were retrieved in CNKI and PubMed databases (1971-01/2014-12). The key words were“porous bioceramic, bone tissue engineering, bone morphogenetic protein-2, induced pluripotent stem cel s”in Chinese and English, respectively. A total of 54 articles based on inclusion criteria and exclusion criteria were obtained for the review. RESULTS AND CONCLUSION:Porous gradient hydroxyapatite/zirconia composite can provide a scaffold to induce natural y forming bone growing to fil the three-dimensional pores, thus realizing the perfect integration of tissue-engineered bone material and host-bone tissue. As zirconia functions as an enhancer of hydroxyapatite, high-quality artificial bone materials, which have elastic modulus, fracture toughness and structure similar to human bone, can be prepared by adjusting the proportion and porosity of materials. Additional y, the new hydroxyapatite/zirconia foamed ceramics as tissue-engineered bone carrying bone morphogenetic protein-2/chitosan gel sustained release system and bone marrow mesenchymal stem cel s derived from induced pluripotent stem cel s wil be expected to increase bone formation and bone fusion rates significantly in the future.
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Objective To evaluate and compare the clinical outcome of coracoclavicular screw and double Endobutton plate in treatment of acromioclavicular dislocation ( Rockwood Ⅲ-Ⅴ ). Methods Twenty-eight patients with Rockwood Ⅲ-Ⅴ acromioclavicular dislocation were subjected to surgical reconstruction from January 2008 to October 2009. The coracoclavicular screw was performed in 14 patients and the double Endobutton plate in the other 14 patients. Clinical evaluation was performed by using Constant score and subject should value (SSV) in both groups, and the preoperative and postoperative radiographs, curative effects and complications were compared. Results The patients in two groups were followed up for a range of 6-25 months (average 12.6 months) , which showed higher postoperative Constant score and SSV score than preoperation in both groups (P＜0.05). But the postoperative Constant sore and postoperative SSV score in the double Endobutton group were (89.8 ±8.3) points and (85.7 ±7. 3) points respectively, significantly better than (78. 0 ± 10. 3) points and (71. 8 ±9. 7) points respectively in the coracoclavicular screw group ( P ＜ 0.05). The radiologic measurement showed no significant difference in regard of the coracoclavicular distance three months after operation in two groups (P＞0.05). Conclusions The double Endobutton plate can attain significantly superior clinical outcomes for Rockwood Ⅲ-Ⅴ acromioclavicular dislocation compared with the coracoclavicular screw. The surgical technique of reconstructing the coracoclavicular ligament through anatomical approach will be the future trend in treatment of the acromioclavicular joint dislocation.