Osseointegration of additive manufacturing Ti-6Al-4V and Co-Cr-Mo alloys, with and without surface functionalization with hydroxyapatite and type I collagen

Silvia Brogini, Maria Sartori, Gianluca Giavaresi, Patrizio Cremascoli, Fabio Alemani, Davide Bellini, Lucia Martini, Melania Maglio, Stefania Pagani, Milena Fini

Research output: Contribution to journalArticlepeer-review


The introduction of additive manufacturing (AM) technologies has profoundly revolutionized the implant manufacturing industry, with a particularly significant impact on the field of orthopedics. Electron Beam Melting (EBM) and Direct Metal Laser Sintering (DMLS) represents AM fabrication techniques with a pivotal role in the realization of complex and innovative structure starting from virtual 3D model data. In this study, Ti-6Al-4V and Co-Cr-Mo materials, developed by EBM (Ti-POR) and DMLS (Co-POR) techniques, respectively, with hydroxyapatite (Ti-POR + HA; Co-POR + HA) and type I collagen (Ti-POR-COLL; Co-POR-COLL) coatings, were implanted into lateral femoral condyles of rabbits. Osseointegration process was investigated by histological, histomorphometrical and microhardness evaluations at 4 and 12 weeks after implantation. Both Ti-6Al-4V and Co-Cr-Mo implants, with or without HA and COLL coatings, demonstrated good biocompatibility. As expected, HA coating hastened bone-to-implant contact (BIC) process, while collagen did not significantly improved the osseointegration process in comparison to controls. Regarding newly trabecular bone formation (B.Ar/T.Ar), Co-POR presented the highest values, significantly different from those of Co-POR-COLL. Over time, an increase of BIC parameter and a decrease of B.Ar/T.Ar were detected. Higher mineral apposition rate was observed for Ti-POR and Co-POR in comparison to Ti-POR-COLL and Co-POR-COLL, respectively, at 12 weeks. The same behavior was found for bone formation rate between Co-POR and Co-POR-COLL at 12 weeks. In conclusion, the AM materials guarantee a good osseointegration and provide a suitable environment for bone regeneration with the peculiarity of allowing personalized and patient-specific needs customization to further improve the long-term clinical outcomes.

Original languageEnglish
Pages (from-to)104262
JournalJournal of the Mechanical Behavior of Biomedical Materials
Publication statusE-pub ahead of print - Dec 10 2020


  • Additive manufacturing
  • Coating
  • Hydroxyapatite
  • In vivo study
  • Metal medical device
  • Osseointegration
  • Type I collagen

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