Chinese Journal of Tissue Engineering Research ›› 2021, Vol. 25 ›› Issue (28): 4441-4446.doi: 10.12307/2021.055

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Three-dimensional printed porous titanium alloy scaffolds with different apertures in repair of femoral defects in rabbits: 600 μm aperture is more conducive to osseointegration

Wang Qing1, Weng Yiping2, Liu Hongwei2, Zhang Wen3, Shi Qin3, Zhang Runze1, Jiang Junfeng4, Wang Caimei5   

  1. 1Graduate School, Dalian Medical University, Dalian 116044, Liaoning Province, China; 2Department of Orthopedics, Changzhou Second People’s Hospital Affiliated to Nanjing Medical University, Changzhou 213003, Jiangsu Province, China; 3Institute of Orthopedics, Soochow University, Suzhou 215006, Jiangsu Province, China; 4School of Internet of Things Engineering, Hehai University, Changzhou 213022, Jiangsu Province, China; 5Beijing Aikang Yicheng Co., Ltd., Beijing 102200, China
  • Received:2020-07-01 Revised:2020-07-04 Accepted:2020-08-15 Online:2021-10-08 Published:2021-05-15
  • Contact: Liu Hongwei, Chief physician, Department of Orthopedics, Changzhou Second People’s Hospital Affiliated to Nanjing Medical University, Changzhou 213003, Jiangsu Province, China E-mail:lhw_2689@qq.com
  • About author:Wang Qing, Master candidate, Physician, Graduate School, Dalian Medical University, Dalian 116044, Liaoning Province, China
  • Supported by:
    the National Natural Science Foundation of China, No. 61772172 (to JJF and LHW); the Major Project Funding Project of Changzhou Municipal Health Planning Commission, No. ZD201617 (to LHW)

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Abstract:

BACKGROUND: The microporous structure of a porous titanium alloy can not only provide sufficient space for the proliferation and migration of osteoblasts, but also promote the angiogenesis of mesenchymal stem cells, affect the expression of osteogenic genes and the differentiation of osteoblasts, which is an important factor for bone integration.

OBJECTIVE: To analyze the osseointegration ability of three-dimensional printed porous titanium alloy scaffolds with different apertures in repairing rabbit femoral condyle defect.
METHODS: Totally 40 hind legs of 20 New Zealand rabbits were randomly divided into group A, group B, group C, and group D. A 5 mm×5 mm bone defect model was established. Groups A, B, and C were implanted with porous titanium alloy scaffolds with a diameter of 200, 600, and 1 000 μm, while group D was not implanted. X-ray films were taken at 4 and 8 weeks after operation to observe whether there was displacement, prolapse and osteolysis, and osteonecrosis around the implants. At 8 weeks after operation, the trabecular thickness, trabecular number, trabecular volume, bone surface area density, and trabecular separation were detected by micro CT. The osseointegration was observed by histology. The experimental protocol was approved by the Animal Experiment Ethics Committee of Soochow University. 
RESULTS AND CONCLUSION: (1) X-ray films showed that the implants were in good position, without obvious displacement or falling off, and the bone around the materials was good, without osteolysis, osteonecrosis or other bad phenomena. (2) Micro-CT examination showed that bone tissue existed in the pores and around the implants in three groups. The number of trabeculae and bone surface area density in group B were significantly higher than those in the groups A and C (P < 0.05). The trabecular thickness of micropores in the group A was significantly higher than that in the groups B and C (P < 0.05). (3) Toluidine blue staining showed that the new bone tissue grew into almost all the surface micropores in group B, and some of the new bone extended into the deep pores of the experimental scaffold, closely combined with the porous structure, forming mechanical interlocking. Groups A and C had only a small amount of new bone tissues in surface micropores, and there was not new bone tissues in deep pores. The combination of new bone and implant was poor. (4) The results showed that the three-dimensional printed porous titanium alloy scaffold with 600 μm aperture was more conducive to new bone formation compared with 200 μm and 1 000 μm aperture.

Key words: bone, material, aperture, porosity, titanium alloy, new bone formation, 3D printing, electron beam melting, bone defect

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