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OXINIUM™
Oxidized Zirconium and counterface
review
™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
Outline
• Bearings choices for hard on soft articulation
• OXINIUM™
Oxidized Zirconium
• OXINIUM knee –
laboratory studies
• OXINIUM knee –
clinical studies
• OXINIUM hip –
laboratory studies
• OXINIUM hip –
clinical studies
™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
Desired attributes of hard bearings in hard on soft articulationBulk material attributes
•
Biocompatible
•
Corrosion resistant
•
Suitability for metal sensitive patients
•
Chemically and mechanically stable over extended period of time
Bearing surface attributes to reduce PE wear
•
Low friction and wettable
•
Scratch or abrasion resistant to third body debris such as bone cement
•
Macro-damage resistance (instrument damage, chipping, taper damage-compatibility, fracture risk, etc)
Choices of hard bearing materials
•
CoCr
alloy (as-cast, forged or wrought)
•
Surface hardened CoCr
•
Surface hardened Ti6Al4V alloy (wrought or forged)
•
Ceramic coatings
•
Monolithic ceramic such as yttria
stabilized zirconia, alumina (Forte), zirconia
toughened alumina (Delta)
•
OXINIUM™
Oxidized Zirconium
™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
CoCr
Alloy
•
Long clinical history
•
Does contain Nickel which is known to cause allergic response in some patients
•
Less scratch resistant to bone cement debris compared to some of the advanced bearing materials
Scratches on retrieved CoCrdue to bone cement debris
Allergic response to a CoCr
knee femoral(Nasser et al., AAOS 2007)
Ni content for Ti and CoCr
is permissible content per ASTM, actual content may be less, Internal Specification of Ni for Zr2.5Nb <0.0035%
Ion treated CoCr
•
Increase surface hardness of CoCr
to improve wettability
and abrasion resistance
•
Sold by Stryker under trade name “LFIT”
(Low Friction Ion Treated)
•
Small depth of hardening (~0.2 micron)
•
Retrieval analysis has shown that ion treated layer can disappear over time*
*McGrory et.al., AAOS 2005
Ti6Al4V alloy
•
Not a favored material for bearing application
•
Promoted as an alternate to CoCr
for metal sensitive patients by some companies
•
Nitrogen diffusion hardened Ti6Al4V sold by Zimmer
•
Depth of hardening is small and hardened layer will eventually wear through and scratch the femoral leading to increased wear of polyethylene
Scratching of nitrogen ion implanted Ti6Al4V during knee simulator test(Shetty
et.al., ASTM-
STP, 1272,1996)
Ceramic coatings
•
Ceramic coating to improve hardness and abrasion resistance
•
Coating adhesion critical to the performance, third body debris can wear the coating, coating debris can scratch CoCr
and will increase wear of polyethylene
Aesculap
ZrN
coated CoCr
Endotec
TiN
coating on Ti6Al4V
TiNbN
coating* –
Vanguard-Biomet*Haider
et. Al. Trans. 54th ORS, poster 2007, 2008
Coating delamination
TiNbN ZrN
Wear through of the coating during bone cement abrasion test(Hunter et al., MPMD, 2004)
Monolithic ceramics
•
Yttria
stabilized zirconia, Alumina and zirconia
toughened alumina (ZTA or Delta) are preferred materials of choice
•
Difficult to put porous structure for non-cemented use in knee femoral
•
Ceramic knees not cleared in US
•
Finite fracture risk
•
Phase transformation leading to roughening or fracture pose long term concern on stability
Biolox
Delta-CeramTec
AGYttira
stabilized zirconia
ceramic JMM, Japan
!"90ß=#=90
!
ß
#
Monoclinic
a
c
a!c
Tetragonal
5% Volume increase
Stable phase of zirconium oxide in the oxide of OXINIUM™
Oxidized Zirconium
Metastable
phase of zirconium dioxide in ytrria
stabilized zirconia
and Delta™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
OXINIUM™
Oxidized Zirconium
•
Base alloy of the OXINIUM material is zirconium-2.5 wt% niobium (Zr-2.5Nb)
•
Oxidized to form a hard ceramic surface
•
Zirconium is one of the five most biocompatible elements (titanium, zirconium, niobium, tantalum and platinum)
•
Ni content of Zr2.5Nb alloys is extremely low making it suitable for metal sensitive patients
•
Other uses of Zirconium alloys
–
Chemical industries (valves and seals)
–
Nuclear fuel rods™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
OXINIUM™
Oxidized Zirconium
•
Wrought zirconium-2.5 niobium device is heated in air
•
Surface transforms to stable ceramic (~5 !m), not a coating
•
The OXINIUM alloy is durable with toughness of metal and high strength
Metal Substrate
Oxygen Enriched MetalOriginal Surface
Air500oCOxygen
Diffusion
Ceramic Oxide
Oxygen Enriched Metal
*Hunter et al., J ASTM Intl 2005
™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
Hardness
Hardness of Oxide of OXINIUM™
devices is twice
that of CoCr
*Long et al., SFB 1998™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
Oxide integrity
Adhesion and cohesion of the oxide excellent
•
“Brick-like”
structure perpendicular to surface
•
No pores or segregation internally or at interface
*Hobbs et al., J Appl
Ceram Tech 2005
Ceramic Oxide
Zr2.5Nb
Rectangular Monoclinic Crystals of Zirconia
TEM Image*
Strength
•
Supports 4.4 kN
(~1000 lbf) for 10 million cycles –
equivalent to CoCr
•
Bends with 19.8 kN
(~4500 lbf) –
does not break or delaminate
Tsai et al., SFB 2001
Abrasion resistance
Hunter and Long, WBC 2000
4,900 times less volumetric wear in bone cement abrasion test compared to CoCr, Ceramic coated disks show wear through
Wear through of the coating during bone cement abrasion test(Hunter et al., MPMD, 2004)
TiNbN ZrN
CoCrOXINIUM
™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
Damage tolerance
Resists oxide removal even if damaged
•
10 Mcycle
bone cement abrasion test across a groove milled through the oxide*
*Hunter, SFB 2001
MilledGroove
Pin Motion
OxideSurface
MetalSubstrate
*Hunter, SFB 2001
Coefficient of friction
•
Lower coefficient of friction against polyethylene and against cartilage
•
Lower coefficient of friction means less adhesive wear of polyethylene
Poggie et al., ASTM STP 1145™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
™
Interfacial friction and heat generation*
•
Lower friction leads to lower interfacial temperature
•
Thermal conductivity (heat dissipation also critical)
•
OXINIUM™-ceramic surface provides lower friction and bulk metal provides higher thermal conductivity
•
Alumina and OXINIUM heads generated less heat compared to yttria
stabilized zirconia.
0
5
10
15
20
25
30
35
40
45
1.0Hz 0.5 Hz 1.0Hz 0.5 Hz
Tem
pera
ture
Diff
eren
ce (d
egC) Alumina
OxZrCoCrZirconia
Test Frequency Test Frequency
LINERHEAD
*Tsai et al., Key Eng. Matls. 2006™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
Wettability
•
A drop of fluid beads up more on a CoCr
surface
•
A drop of fluid lies down more on a ceramic surface
•
The ceramic surface of Oxidized Zirconium slides better than Cobalt Chrome because it lubricates better
Drop of fluid on a ceramic surface
Drop of fluid on a CoCr surface
*Sprague et al., ISTA 2003
Chemical and mechanical stability
•
Chemically stable after 20 hrs of steam autoclave (~simulated ageing of >80 years in-vivo)*
•
Does not shatter in crush test with 89 kN
(20,000 lbf) load–
Flattens slightly with 89 kN
side load without stem
–
Oxide maintains integrity on slightly flattened head
Zirconia OXINIUM™
head
Top load Side load*Sprague et al., ISTA 2003
™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
OXINIUM™
Oxidized Zirconium –
key messages
•
Ceramic bearing surface without a risk of fracture
•
Surface transformation, not a coating
•
Suitable for metal sensitive patients
•
Highly wettable, abrasion resistant and low friction ceramic surface
•
Long term mechanical and chemical stability
•
Like other surfaces can get damaged intraoperatively, care needs to be exercised with all the bearing surfaces
™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
OXINIUM™
knee –
laboratory studies
™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
Knee simulator test (benign)
OXINIUM™
femorals
reduced conventional PE wear rate by 85%
Spector et al., JBJS, 2001™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
0
5
10
15
20
25
30
35
40
Benign HiRot HiVarus
Wea
r Rat
e (m
m3
/ M
cycl
e) CoCrOxZirc
0
5
10
15
20
25
30
35
40
Benign HiRot HiVarus
Wea
r Rat
e (m
m3
/ M
cycl
e) CoCrOxZirc
*Ezzet et.al., CORR 2004, ** Ezzet
et.al., Trans. ORS, 2005
Independent Wear Study: Scripps Institute
•
Testing done at Independent Lab (Scripps Institute in San Diego)
•
42% wear reduction –
benign conditions*
•
40–60% wear reduction –
high rotation & high varus**
VERILAST™
Technology: OXINIUM™
Knee Femoral and 7.5 XLPE*
VERILAST Technology provides the lowest wear
™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
OXINIUM™
knee –
clinical studies
™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
OXINIUM™
knee and hip implantations
As of 2009, over 200,000 knee femorals and 100,000 femoral heads implanted
•
First total knee in December 1997
•
First total hip in October 2002
™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
Laskin, Tech. Knee Surgery 6(4), 220-226,2007
OXINIUM CoCrMo
Mean flex 119º 116º
Knee score 91 92
Function score 76 72
™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
Clinical study knees –
5 year clinical results
•
First Study
72 Patients with OXINIUM™
knees mean follow-up 5.6 years, safety study
•
Second study (randomized) compare CoCr
and OXINIUM knees (38 patients)
•
No specific complications associated with OXINIUM knees
Clinical study knees >5 year clinical results
•
98 Patients, minimum follow-up 5 years, Implanted between April 2001 to December 2003
•
98.7% survival rate at 7 years (95% CI , 90.3%–99.8%)
•
Worst case scenario of patients losing follow-up, gives 94.5% survivorship at 7 years
*Innocenti
et al.,CORR, DOI 10.1007/s11999-009-1109-y, 2009
*
In-vivo temperature measurements*
Increase in temperature in the joint space for healthy knee, arthritic knee, different designs and OXINIUM™
knee
femoral components was measured
*Pritchett, CORR, 442,2006,195-198
OXINIUM knee
™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
Metal sensitivity case study*
•
56 year old homemaker, cannot wear jewelry
•
Left Knee: 3 years post TKA (CoCr)
–
Pain & stiffness
–
Persistent rash
•
Revised to Alumina
–
Rash went away
•
Right knee primary with OXINIUM™
material: Rash did not appear
*Nasser et al., AAOS 2007™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
Retrieval analysis*
•
Matched pair analysis of OXINIUM™
Oxidized Zirconium and CoCr
knee femorals
and tibial
inserts
•
In-vivo time similar
•
Wear score of inserts and of femoral components graded
•
Lower wear score of OXINIUM femorals
and corresponding inserts
0
10
20
30
40
50
60
70
80
90
Inserts/CoCr Inserts/OXINIUM
Tibi
al In
sert
Wea
r Sco
re
*Heyse et al., ESSKA, 2010, Oslo, Norway
0
2
4
6
8
10
12
CoCr OXINIUM
Fem
oral
Dam
age
Wea
r Sco
re
™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
Retrieval analysis
•
9 OXINIUM™
and 9 CoCr
knee femoral components*
•
In-vivo time
–
OXINIUM (1.2 to 5.6 yrs)
–
CoCr
(0.7 to 4.6 yrs)
•
Articulating surface roughness measurements
•
CoCr
components rougher than OXINIUM knee femorals
*Sebastian et al., Trans. 54th
ORS, 2008
™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
OXINIUM™
hip –
laboratory studies
™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
Hip simulator wear test (benign)
•
Reduces non-irradiated poly wear rate by 45%*
•
Generates approximately 30% fewer particles
0
10
20
30
40
Non-Irradiated CrosslinkedPolyethylene Liner
Agg
rega
te W
ear R
ate
(mm
3 /Mcy
cle)
CoCrOx. Zirc.
N/D N/D 0
2
4
6
8
10
Non-Irradiated CrosslinkedPolyethylene Liner
Line
r Wea
r Par
ticle
s (m
illion
s/cy
cle)
CoCrOx. Zirc.
*Good et al., JBJS-A 2003*Good et al., JBJS-A 2003
Hip simulator wear test with abraded heads
•
CoCr
and OXINIUM™
heads roughened to simulate presence of third body debris in the joint
•
Tumbled OXINIUM head has same wear rate as new CoCr head
Smooth Rough0
10
20
Wea
r Rat
e (m
m3 /M
cycl
e) Against OXINIUM heads
Against CoCr heads
Good et al., JBJS 2003™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
Hip simulator wear test (jogging protocol)
Parikh et al., Trans. 55th ORS, 2340, 2009
-10
-5
0
5
10
15
20
25
30
0 1 2 3 4 5 6 7 8
Cycles (millions)
Cum
ulat
ive
Wea
r (m
m3 )
HL001123 Verse CoCr HeadHL001125 Verse CoCr HeadHL001127 Verse CoCr HeadHL001122 Verse Oxinium HeadHL001124 Verse Oxinium HeadHL001126 Verse Oxinium Head
Against CoCr heads
Against OXINIUM heads
™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
0
10
20
30
40
50
60
32mm CoCr/CPE 36mm Delta/XLPE 36mm Ox/XLPE
Wea
r Rat
e m
m3 /M
cycl
e
CoCr/CPE, OXINIUM™/XLPE and Delta/XLPE under jogging protocol
32 mm CoCr/CPE: Parikh et al., ORS 2009, 36 mm Delta/XLPE and Ox/XLPE –Data on file
~95%
™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
Large heads against XLPE
•
Large heads offer more joint stability and range of motion
•
Wear of 44mm OXINIUM™/XLPE is less than 36mm CoCr/XLPE (p<0.05)*
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Against 36mm CoCr heads Against 44mm OXINIUM heads
Cum
ulat
ive
Wea
r (m
m3 )
Parikh et al., ISTA 2010™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
OXINIUM™
hips –
clinical studies
™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
Linear wear
•
RSA study in Australia:–
30 patients with 32mm OXINIUM™/XLPE (10Mrad)
–
28mm CoCr/XLPE (5 and 10 Mrad)
–
28mm CoCr/ETO sterilized UHMWPE
•
OXINIUM/XLPE-10 shows promising results
Li et al., Trans. 52nd
ORS, 0643,2006 ™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
Linear wear
•
2 year follow-up,
–
CoCr/XLPE
–
OXINIUM™/CPE
–
OXINIUM/XLPE
•
270 patients prospectively randomized consecutive, all heads 32 mm
•
Reviewers blinded
•
OXINIUM/XLPE shows lowest wear
Haddad et.al., Proc. AAOS, P067, 2010
CoCr/XLPE Ox/CPE Ox/XLPE
™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
Clinical Outcome*
•
Randomized study –
50 patients received OXINIUM™
femoral heads
–
50 patients received CoCr
femoral heads
•
Minimum follow-up 2 years
•
Authors conclude use of OXINIUM heads is safe and effective
*Lewis et.al., ISTA 2009 ™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.
Retrieval analysis: phase stability
•
Comparison of OXINIUM™, yttria
stabilized zirconia
(YTZ) and Delta (contains yttria
stabilized zirconia~17 volume %)*,**
•
Monoclinic content and surface roughness measured
•
Both YTZ and Delta showed phase transformation,
•
OXINIUM is stable monoclinic so no phase transformation observed
*Medel
et al., Trans. 55th
ORS,2300, 2009**Sakona
et al., Trans. 56th
ORS, 2358A, 2010
Tetragonal peak absent for OXINIUM
Raman spectra**
™Trademark of Smith & Nephew. Reg. US Pat. & TM Off.