J. Mater. Sci. Technol. ›› 2017, Vol. 33 ›› Issue (2): 179-186.DOI: 10.1016/j.jmst.2016.05.013.

• Orginal Article • Previous Articles     Next Articles

Hierarchical Micropore/Nanorod Apatite Hybrids In-Situ Grown from 3-D Printed Macroporous Ti6Al4V Implants with Improved Bioactivity and Osseointegration

Xiu Peng1,2,Jia Zhaojun3,Lv Jia1,2,Yin Chuan1,2,Cai Hong1,2,Song Chunli1,2,Leng Huijie1,2,Zheng Yufeng3,4,Liu1 Zhongjun2,*,Cheng Yan3,*   

  1. 1 Department of Orthopedics, Peking University Third Hospital, Beijing 100191, China
    2 Beijing Key Laboratory of Spinal Diseases, Beijing 100191, China
    3 Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
    4 Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China
  • Received:2016-04-05 Accepted:2016-05-06 Online:2017-02-20 Published:2017-05-23
  • Contact: Liu1 Zhongjun,Cheng Yan

Abstract:

The advent of three-dimensional (3-D) printed technique provides great possibility in the fabrication of customized porous titanium (Ti) implant. However, the bioinert property of the printed Ti poses an outstanding problem. Hybrid micro-arc oxidation and hydrothermal (MAO-HT) treatment on porous metals is able to produce multi-scaled hierarchical orthopedic implant, showing great potential for surface modification of 3-D printed implant. In this study, cylindrical porous Ti6Al4V (Ti64) scaffolds with pore size of 640?µm, porosity of 73% were 3-D printed by electron beam melting process, and their surfaces were left untreated or treated by a combined MAO-HT procedure. In vitro bioactivity was tested by immersion in simulated body fluid for different time points. Then, 12 scaffolds in each group were implanted into the femoral condyles of New Zealand rabbit for 8 weeks. Osseointegration was evaluated by qualitative and quantitative histological analysis, and the bone ingrowth features were probed by sequential fluorescent labeling at 3 and 6 weeks post-surgery. Following the MAO-HT treatment, the porous Ti64 scaffold was endowed with multi-scaled micro/nano-topographies and high amounts of CaP on its surface. The treated scaffold exhibited drastically enhanced apatite forming ability compared with the untreated one. In vivo test revealed significantly that a higher amount of bone ingrowth and bone implant contact at the treated scaffold. The 2 types of scaffolds had different patterns of bone ingrowth: the treated scaffold exhibited a pattern of contact osteogenesis, by which bone formed directly on the treated implant surface, whereas bone formed distal to the implant surface of the untreated scaffold. MAO-HT treatment can significantly enhance the in vitro apatite-inducing ability and in vivo osseointegration capacity of 3-D porous Ti64 scaffold and may provide as a viable approach for the fabrication of bioactive 3-D printed porous implant for orthopedic applications.

Key words: 3-D printing, Porous Ti6Al4V, Micro-arc oxidation, Hydrothermal treatment, Osseointegration