The control of surface properties to reduce wear and corrosion and improve biocompatibility is of particular interest today as device companies—and surgeons, payors and patients—seek to extend the life of knee and hip implants. In this session, device companies shared research on their joint replacement coatings and materials, covering pros, cons and the future of their technology.

2. Supporting healthcare
professionals for over 150 years
Supporting healthcare
professionals for over 150 years
Gordon Hunter, Ph.D.
OMTEC: June 12, 2019
Articular Surface
Enhancement for Joints
(featuring OXINIUM™ Technology)
◊Trademark of Smith & Nephew

3. Polyethylene Wear in the Knee
• Loosening and wear can limit long-term survivorship1
1Sharkey PF, Lichstein PM, Shen C, Tokarski AT, Parvizi J. Why Are Total Knee Arthroplasties Failing Today – Has Anything Changed After 10 Years? J
Arthroplasty. 2014;29;1774-1778.

4. Sliding Wear Mechanisms
• Adhesive (friction)
• Abrasive (roughness)

5. CoCr Wear Issues
• Abrasive and oxidative
wear roughen CoCr
–Bone cement
–Bone
–Fretting debris
–Shed in-growth particles
• Clinically observed
scratches can increase
wear1
Peak
Condyle
Surface
Valley
Knee3Hip2
1Fisher J, Firkins P, Reeves EA, Hailey JL, Isaac GH. The influence of scratches to metallic counterfaces on the wear of ultra-high molecular weight polyethylene.
Proc Inst Mech Eng H. 1995;209(4):263-264.
2Barrack RL, Castro FP, Szuszczewicz ES, Schmalzried TP. Analysis of Retrieved Uncemented Porous-Coated Acetabular Components in Patients With and
Without Pelvic Osteolysis. Orthopedics. 2002;25(12):1373-1378.
3Levesque M, Livingston BJ, Jones WM, Spector M. Scratches on condyles in normal functioning total knee arthroplasty. Paper presented at 44th Annual Meeting
of the ORS, New Orleans, LA, 1998.

6. Ceramic as an Alternative to Metal
• Hard surface resists roughening1-4
–Low articular abrasion
–Low articular friction
• Brittle material has limitations
–Risk for chipping or breaking1
–Part geometry restrictions2
Zirconia Toughened Alumina3
Zirconia Toughened Alumina4
1Tateiwa T, Clarke IC, Williams PA, et al. Ceramic Total Hip Arthoplasty in the United
States: Safety and Risk Issues Revisited. AM J Orthop. 2008;37(2):E26-E31.
2Skinner HB. Ceramic Bearing Surfaces. Clin Orthop Relat Res. 1999;369:83-91.
3Heiner AD, Mahoney CR. Fracture of a BIOLOX Delta Ceramic Femoral Head
Articulating Against a Polyethylene Liner. JBJS Case Connect. 2014;4:e97.
4Krueger AP, Singh G, Beil FT, et al. Ceramic Femoral Component Fracture in Total
Knee Arthroplasty: An Analysis Using Fractography, Fourier-Transform Infrared
Microscopy, Contact Radiography and Histology. J Arthroplasty. 2014;29:1001-1004.

7. Ceramic Coatings to Enhance Metals
• Surface is hard, but may not be effective
–Limited durability with adhesion and/or cohesion1
–Wear may not be less than with metal (CoCr)2
Metal Substrate
Original Surface
Ceramic
Deposition
Ceramic Coating
New Surface
TiNbN Coating
Worn Off
1Hunter G, Pawar V, Salehi A, Long M. Abrasive wear of modified CoCr and Ti-6AL-4V surfaces
against bone cement. Medical Device Materials. S. Shrivastava (ed.), ASM International, Materials
Park, OH. 2004;97-97.
2Haider H, Weisenburger JN, Croson RE, Namavar F, Garvin KL. Concern with adhesion and wear of
a Titanium Niobium Nitride coating on Total Knee Replacements for metal sensitive patients. Poster
presented at 54th Annual Meeting of the ORS, 1998, Poster No. 2007.

8. Oxidation of Zirconium Alloy
• Wrought zirconium alloy metal device is heated in air
• Surface transforms to stable ceramic (~5 µm); not coated1
• Oxide is durable and low-friction with toughness of metal1
Metal Substrate
Oxygen Enriched Metal
Original Surface
Air
500oCOxygen
Diffusion
Ceramic Oxide
Oxygen Enriched Metal
Zr-2.5%Nb Alloy
1Hunter G, Dickinson J, Herb B, Graham R. Creation of Oxidized Zirconium Orthopaedic Implants. J ASTM Intl. 2005;2(7):1-14.

9. High Integrity and Stable Oxide Surface
• Improved durability over passive oxide
–Over 400X thicker than CoCr passive oxide
–“Brick-like” structure perpendicular to surface
–No pores or segregation internally or at interface
–No line-of-sight limitation
Ceramic
Oxide
Metal
Alloy
Rectangular
Monoclinic
Crystals of
Zirconia
TEM Image1
1Hobbs LW, Rosen VB, Mangin SP, Treska M. Oxidation Microstructures and Interfaces in the Oxidized Zirconium Knee, Intl J Appl Ceram Technol. 2005;2(3):221-
246.

10. Less Polyethylene Wear in
Laboratory Simulators
• Reduces wear rate under typical and severe conditions
–Hip Simulator Example1 -Knee Simulator
Example2
1Parikh A, Morrison M, Jani S. Wear testing of crosslinked and conventional UHMWPE against smooth and roughened femoral components. Abstract presented at
53rd Annual Meeting of the ORS, San Diego, CA, 2013. Paper No. 0021.
2Ezzet KA, Hermida JC, Patil S, et al. Wear of polyethylene against metal-ceramic composite femoral component: effect of aggressive kinematic conditions. Poster
presented at 51st Annual Meeting of the ORS, 2006. Poster No. 1239.

11. Extensive Clinical Experience
• Over 20 years of clinical use
–First total knee in Dec. 1997; over 1,200,000 sold
–First total hip in Oct. 2002; over 700,000 sold

12. 1
Review of Long-term Survival (2017)
1Civinni R, Matassi F, Carulli C, et al. Clinical Results of Oxidized Zirconium Femoral Component in TKA. A Review of Long-Term Survival. HSS Journal.
2017;13:32-34.

13. Fewer Clinical Knee Wear Features
• Produced lower wear scores for both surfaces in 1-3 year retrieval
study1,2
–Retrieved component pairs matched for time and patient factors
–Femurs 92% fewer features; inserts 31% fewer features
–Roughness measured by non-contact profilometry; all parameters were
less
CoC
r
OxZ
r
1Heyse TJ, Elpers ME, Nawabi DH, Wright TM, Haas SB. Oxidized Zirconium versus Cobalt-Chromium in TKA: Profilometry of Retrieved Femoral Components. Clin
Orthop Relat Res. 2014;472:277-283.
2Heyse TJ, Chen DX, Kelly N, et al. Matched-pair total knee arthroplasty retrieval analysis:Oxidized zirconium vs. CoCrMo. The Knee. 2011;18:448-452.

14. Unsurpassed Survivorship in Hips
• OXINIUM/XLPE hips achieved 96.5% survivorship at 10 years1
“… the Registry urges
caution in the
interpretation of this result.
This bearing is a single
company product, used
with a small number of
femoral stem and
acetabular component
combinations. This may
have a confounding effect
on the outcome, making it
unclear if the lower rate of
revision is an effect of the
bearing surface or reflects
the limited combination of
femoral and acetabular
prostheses.”
1Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). Hip, Knee & Shoulder Arthroplasty: 2018 Annual Report. Adelaide: AOA,
2018. Figure has been reproduced in exact and complete form. For a full copy of the AOA National Joint Replacement Registry report, see
aoanjrr.sahmri.com/annual-reports-2018.

15. Summary
• Oxidized zirconium addresses the limitations of ceramic coatings
• Nearly 2 million joints sold in the past 20 years
• Excellent clinical outcomes and low revision rates out to 12 years
–No known major complications
–No known unexpected failure mechanisms
• Lower roughness than CoCr on retrieved components
–Confirms lab studies
–Indicates promise for longer term results