Layer Manufacturing of Porous Titanium for Biomedical Applications

Transcription

1 TiDA ITPPCM Conference Layer Manufacturing of Porous Titanium for Biomedical Applications UOW, Hamilton Seung Eon Kim, Jae Keun Hong, Yong Taek Hyun, Korea Institute of Materials Science

2 Overview 1 Porous Background metals in medical devices Scaffolds for biomedical use 2 Need of layer manufacturing (LM) technologies 3 HA/PCL Fabrication scaffolds of 3D for porous bone regeneration Ti by LM in KIMS Titanium scaffolds for bone replacement 4 Characterization of biocompatibilites 5 Summary

3 Porous metals in medical devices Bead coated stem Mesh coated stem Dental Implant Acetabular cup Femoral component Artificial disc Fusion cage

4 Typical pore structures Sintered bead Fiber mesh Anodized Trabecular/Cellular

5 Limits of bone ingrowth depth Proximal part of hip stem after removal (in-vivo) Surface bone tissues Cross section bone tissues surface surface Trabecular Metal TM and bone ingowth (in-vivo) center Trabecular Metal TM - Zimmer

6 Bone healing process Hematoma Vascularization Bony Callus Remodeling Critical sized defect - Mouse : 5 mm - Rat : 8 mm - Rabbit : 15 mm - Dog : 20 mm - Cat : 25 mm Critical sized defect is defined as a defect that heals by less than 10% bony regeneration during the lifetime of the individual. 0W 16W 0W 4W 16W

7 Need Advantages of 3D porous of 3D porous implants implants Good tissue ingrowth Pore design variety On-demand forming Process reliability

8 Layer manufacturing (LM) Rapid prototyping (RP) Solid freeform fabrication (SFF) Layer manufacturing (LM) 3D printing (3DP) Additive manufacturing (AM) the 3D printing that has the potential to revolutionize the way we make almost everything.. President Obama in the State of the Union Address, Feb. 12, 2013 ASTM F a designates definitions, descriptions, nomenclature, acronyms, and categories associated with AM technologies.

9 LM technologies for medical devices Partial dentures and crowns : SLS by EOS Acetabular cups and prostheses: EBM by Arcam Hip joint replacement : DMT by Insstek Titanium jaw prosthesis: SLS by LayerWise

10 LM process in KIMS Metal Paste Deposition (MPD) z x Syringe y Nozzle Metal paste KIMS-LM machine

11 Fabrication of 3D porous Ti by LM Processing route Ti powders + PCL Sol. HDH, 45 mm, 0.33wt%O LM Process MPD Solvent extraction Ethanol, 30 min. 3 times Type I Type II Type III Sintering 300 o C, 2hr, 10-4 torr 1200 o C, 2hr, 10-5 torr 3D Porous Ti f8x1.5 mm,, f5x8 mm * Strand diameter : 0.35 mm, Road gap variation: 0.65~1.0 mm

12 Porosity(%) Pore structure analysis Porosity Pore size distribution - Archimedes method - Scanning electron microscopy (vol. %) - Mercury porosimetry Type Road gap (mm) Type I Type II ~500 mm : coarse pore 50~100 mm : intermediate pore 5~10 mm : fine pore Type III Intermediate & fine pores in strands Road gap(mm) TYPE1 TYPE2 TYPE3

13 Mechanical properties Mechanical properties of 3D porous Ti* compared with human bone Material Max. strength (MPa) Elastic modulus (GPa) Porosity (%) Cortical bone-l 131~224 17~20 - Cortical bone-t 106~133 6~13 - Trabecular bone 10~ ~96 PLA PLA/10HA LM-Type I LM-Type II LM-Type III * compression test, f5 x8 mml, road gap 1.0 mm

14 O.D Cytotoxicity assessment Cytotoxicity test (ISO 10993) - Extraction for 72 hours - Fibroblast (L929) culture for 72 hours - L-glutamin(300mg/L) - 25mM HEPES, 25mM NaHCO3, 10% FBS - MTT assay Type I Type II Type III Control Type I Type II Type III Cell culture (37, 72h) MTT assay Type I Type II Type III Control Extraction (37, 72h) day

15 Live and dead cell assay Type I Type II Type III Control Live cell Dead cell Combined

16 In vivo study Implantation of 3D porous titanium using rat s calvarial defect model (Coperative study with College of Veterinary Medicine, Chonnam National University) - Critical size defect: 8mm Type I Type II Type III Type I Type II Type III

17 Tissue restoration after 4 weeks Type I Type II Tissue X-ray

18 Bone ingrowth with Type I implants A Critical defect (control) Boundary between defect and host bone B Type I implant osteoid host bone C Type I + Growth factor * HA/PCL Type I porous implants, 4 weeks, H&E staining

19 Tissue ingrowth with Type II implants Trabecular /cellular structure center surface 3D porous Structure (Type II) center surface * HA/PCL, Subcutaneous implantation, 4 weeks, H&E staining

20 0 P P Surface treatmant of 3D porous Ti Enhancement of bioactivity by anodizing C o u n t s 6000 Ti O Ti Ca Ca Ca Ca Ti E n e r g y ( k e V ) SBF soaking, 7 days OD 0.1M CA 0.02M bgp 0.15M CA 0.02M bgp Contol DMEM-HG Anodized ANO 0.2M CA Sintered 0.02M Non-Ano bgp L929 culture, 3 days, MTT assay

21 HA conjugated 3D porous Ti Osteoblast-like MG63 cell culture - DMEM, 10% FBS, 1% P/S, 37 o C, 5% CO 2 3D Porous Ti+HA composite HA Ti 20min. MG63 MG63 30min. ECM 60min. 30mm * ECM : Extra Cellular Matrix

22 Potential applications Spinal cages (Co-work with Ulsan University Hospital) Zimmer Trabecular Metal TM - Max. strength : 50~80 MPa - Elas. Modulus : 3 GPa - Porosity : 70~80 % KIMS 3D porous Ti - Max. strength : 24~91 MPa - Elas. Modulus : 1.3~2.8 GPa - Porosity : 65~68 % Calvarial plugs

23 Challenges Shear/distrotion resistance Oxygen pick up Heat affected microstucture Low fatigue strength Standardizations Approvals (FDA, CE, etc.) Mass production

24 Acknowledgements ^ ^ Thank you!