P2000 - A high-nitrogen austenitic steel for application in bone surgery

PLoS One. 2019 Mar 26;14(3):e0214384. doi: 10.1371/journal.pone.0214384. eCollection 2019.

Abstract

Optimal treatment of bone fractures with minimal complications requires implant alloys that combine high strength with high ductility. Today, TiAl6V4 titanium and 316L steel are the most applied alloys in bone surgery, whereas both share advantages and disadvantages. The nickel-free, high-nitrogen austenitic steel X13CrMnMoN18-14-3 (1.4452, brand name: P2000) exhibits high strength in combination with superior ductility. In order to compare suitable alloys for bone implants, we investigated titanium, 316L steel, CoCrMo and P2000 for their biocompatibility and hemocompatibility (according to DIN ISO 10993-5 and 10993-4), cell metabolism, mineralization of osteoblasts, electrochemical and mechanical properties. P2000 exhibited good biocompatibility of fibroblasts and osteoblasts without impairment in vitality or changing of cell morphology. Furthermore, investigation of the osteoblasts function by ALP activity and protein levels of the key transcription factor RUNX2 revealed 2x increased ALP activity and more than 4x increased RUNX2 protein levels for P2000 compared to titanium or 316 steel, respectively. Additionally, analyses of osteoblast biomineralization by Alizarin Red S staining exhibited more than 6x increased significant mineralization of osteoblasts grown on P2000 as compared to titanium. Further, P2000 showed no hemolytic effect and no significant influence on hemocompatibility. Nanoindentation hardness tests of Titanium and 316L specimens exposed an indentation hardness (HIT) of about 4 GPa, whereas CoCrMo and P2000 revealed HIT of 7.5 and 5.6 GPa, respectively. Moreover, an improved corrosion resistance of P2000 compared to 316L steel was observed. In summary, we could demonstrate that the nickel-free high-nitrogen steel P2000 appears to be a promising alternative candidate for applications in bone surgery. As to nearly all aspects like biocompatibility and hemocompatibility, cell metabolism, mineralization of osteoblasts and mechanical properties, P2000 was similar to or revealed advantages against titanium, 316L or CoCrMo.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkaline Phosphatase / metabolism
  • Alloys / chemistry
  • Alloys / pharmacology
  • Animals
  • Bone Diseases / surgery
  • Bone Diseases / therapy
  • Bone Substitutes / chemistry*
  • Bone Substitutes / pharmacology
  • Bone Substitutes / therapeutic use
  • Cell Line
  • Cell Proliferation / drug effects
  • Core Binding Factor alpha Subunits / metabolism
  • Corrosion
  • Hardness
  • Mice
  • Nitrogen / chemistry*
  • Osteoblasts / cytology
  • Osteoblasts / drug effects
  • Osteoblasts / metabolism
  • Prostheses and Implants
  • Stainless Steel / chemistry*
  • Stainless Steel / pharmacology
  • Surface Properties

Substances

  • Alloys
  • Bone Substitutes
  • Core Binding Factor alpha Subunits
  • austenitic steel
  • Stainless Steel
  • Alkaline Phosphatase
  • Nitrogen

Grants and funding

This work was supported by a grant of the Mercator Research Center Ruhr [MERCUR Pr-2015-0047] to B.B, M.D.K and A.F. We acknowledge support by the DFG Open Access Publication Funds of the Ruhr-Universität Bochum. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.