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Coatings: The Power of Bone Integration to Aid Recovery - OMTEC 2018


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Dr. Michael Gentile, DPM, fellow of the American College of Foot and Ankle Surgeons, lends his perspective on future coating technologies and ways to engage coating’s important role in a device. Special focus is given to titanium-integrated PEEK surfaces.

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Coatings: The Power of Bone Integration to Aid Recovery - OMTEC 2018

  1. 1. Healing Efficiently: Improved Bone Cell Responses on Titanium Integrated PEEK Surfaces Michael A. Gentile, DPM, FACFAS Portland, OR
  2. 2. • Private Practice: Northwest Extremity Specialists, LLC • Fellowship Director: Portland Reconstructive Foot and Ankle Fellowship • Attending Faculty: Legacy/Kaiser Portland Podiatric Surgical Residency • Member: Highlands Foot and Ankle Institute
  3. 3. Disclosures Company Intellectual Property Surgeon Advisory Board Consultant Flower Orthopedics X X X Tyber Orthopedics X X Depuy Synthes X
  4. 4. The Grand Conundrum Goals of the Surgeon/Patient vs. Reality. Correction of deformity and retention of results. Implant compatibility and respect for anatomy. Boney healing and return to function. EFFICIENT HEALING
  5. 5. The Status Quo: A Block of Bone Autograft Retains bioactivity. Moot points: Disease transmission and immune response. Donor site morbidity. Allograft Essentially dead bone. Disease transmission and immune response are real concerns. Donor won’t miss it.
  6. 6. Challenging the Paradigm Block of Bone: Requires osseo- integration by creeping substitution. Requires fixation to avoid loss of correction. Allograft requires augmentation. PRP BMAC
  7. 7. Other Than Bone? Titanium Should retain correction. Allows osseointegration. BUT…. Different elastic modulus Stress shielding. Possible subsidence. Chemically active 0 20 40 60 80 100 120 Ti-Alloy Cortical Bone PEEK / TiPEEK Cancellous Bone ElasticModulus(GPa) 17 4 2.3 110
  8. 8. The Elastic Modulus Elastic modulus and stress shielding are ~ directly proportional. Elastic modulus > Bone MAY RESULT in aseptic loosening of implant overtime. Possibly despite efforts to make a more porous titanium. 1. Engh CA et al: JBJS Br 1987: 69(1),45-55. 2. Bobyn et al: Clin Orthop Rel Res 1992: 274, 79-96. 3. Nagels J et al: J Shoulder Elb. Surg. 2003: 12(1), 35-39
  9. 9. The Ideal Alternative Provides predictable and efficient healing. Material is inert and similar to bone. May not require supplemental fixation. Deformity correction is maintained. Potentially quicker return to function. Cost effective.
  10. 10. Why PEEK? Mechanical EPEEK similar to native bone Allows strain transfer to adjacent bone=bone remodeling Visual Radiolucent (PEEK) vs. Radiopaque (Ti) Chemical Bioactive (Ti) vs. Bioinert (PEEK) Topographical Surface features direct cell-substrate interactions Macro, micro, and nano 1. Davies, J. E. Biomaterials 28, 5058–5067 (2007). 2. Kurtz, S. M. & Devine, J. N. Biomaterials 28, 4845–69 (2007). 3. Rho, J. Y., Ashman, R. B. & Turner, C. H. J. Biomech. 26, 111–119 (1993).
  11. 11. Osseointegration: It’s all about the osteoblasts. Adhesion to the implant surface Osteoblast proliferation Bioactivity of the osteoblasts
  12. 12. PEEK Ti-6Al-4V Ti-PEEK Samples characterized for: • Surface topography • Osteoblast response • Adhesion • Proliferation • Calcium deposition This in vitro study examined the response of human osteoblasts to PEEK, titanium, and Ti-PEEK surfaces Cross-sectional SEM of the Ti-PEEK interface
  13. 13. Increased Surface Roughness PEEK Ti Ti-PEEK From atomic force microscopy analysis, the Ti-PEEK surface provides ~30% more surface area per sq. micron of projected area The Ti-PEEK surface exhibits roughness at the macro, micro, and nano levels. Macro: friction fit Micro: cell growth surface area Nano: cell-substrate interactions
  14. 14. Osteoblast Adhesion and Proliferation 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 4 hrs 4 days 7 days 14 days 21 days OsteoblastViability(OD490) PEEK Ti Ti-PEEK * ** * ** * ** * * PEEK Ti Ti-PEEK Osteoblast viability measured via an MTS cell viability assay Data is avg. +/- stdev., N = 3, *p<0.001 compared to PEEK, **p<0.001 compared to Ti • Ti promotes clear improvement compared to PEEK. • Rough Ti-PEEK surface provides more area for proliferation. • Ti-PEEK micro- and nano-features enhance osteoblast differentiation.
  15. 15. Enhanced Osseointegration Surface calcification: TiPeek is superior Up to 305% compared to Titanium Up to 470% compared to PEEK Does this equal less chance of aseptic loosening? Load sharing May be as high 38% irrespective of PEEK porosity or bone ingrowth. Can this allow earlier WB and less aseptic loosening? Economy of time: This can happen as early as 4 weeks.
  16. 16. The Great Race Adequate osseointegration Early mobilization and WB -Less dysfunction -Less aseptic loosening -More predictable results Titanium never catches up to PEEK in terms of load sharing. Titanium has <50% bone ingrowth in short term analysis.1 In fact, bone resorption may actually occur over time.2-5 1. Jensen, W.K., et al.: 2005Spine 30 (22), 2497–2502. 2. Sumner et al: 1995 J Arthroplasy 10(2), 67-67 3. Hanzlik J 2016 Ortop. Proc 98-B (Supp 2). 4. Hanzlik J 2013 J Arthroplasty 28(60, 922-927 5. Hanzlik J 2015 J. Arthroplasty 30(6), 1073-1078
  17. 17. Deformity Correction Cotton wedge used to re-align 1st ray in sagittal plane.
  18. 18. Deformity Correction Evans and Cotton wedges in pediatric flatfoot.
  19. 19. Length Deficits: Current School
  20. 20. Length Deficits: New School
  21. 21. CT Scan
  22. 22. Length Deficits: New School CT scans taken 6 months post surgery • Direct bone apposition on endplates • Bone growth through implant lumen
  26. 26. Bringing It Home Current clinical practice is to utilize blocks of bone. Thought Leaders: Titanium or Titanium coated PEEK (Ti-PEEK). Ti-PEEK makes the most sense: Elastic modulus similar to bone. Titanium coating with unique surface properties: Increase co-efficient of friction. Enhanced osteoblast adhesion and bioactivity. Increased calcium deposition…Osteointegration.