BIOLOX - CeramTec

BIOLOX ®
BIOLOX ® delta – Nanocomposite
for Arthroplasty
The Fourth Generation
of Ceramics
Scientific Information and Performance Data

2
Tribology and Arthroplasty
Competence in Ceramics
Material Properties
The Strengths of BIOLOX ® delta
Key Issues in Hip Arthroplasty
Osteolysis and aseptic
loosening are primarily
triggered by wear
particles, mostly of
polyethylene (left).
Three states of lubrication
are observed in
total hip arthroplasty,
including fluid film lubrication
(A), mixed lubrication
(B) and boundary
lubrication (C). The especially
smooth and
hydrophilic surfaces of
ceramic components
help to ensure that the
wear­reducing lubrication
states A and B are
achieved more often
than in other bearings
(right).
Osteolysis
Although total hip arthroplasty is one of
the most successful of all surgical proce­
dures, a number of open questions relating
to implant design and materials remain.
According to the Swedish Register, osteo­
lysis and aseptic loosening are responsible
for more than 75 percent of all revisions.
The bearing materials used and the volume,
size, and biological effects of wear parti­
cles play a decisive role in the development
of these conditions. The second most fre­
quent complication is dislocation created
by prosthetic impingement and insufficient
joint stability.
Source: OA Dr. H. Hessler, Department of Traumatology,
General Hospital in Celle, Germany
Wear Particles
Particle disease, a condition first identified
by Willert, is triggered by polyethylene (PE)
wear particles. Even the new highly cross­
linked polyethylene (XPE) can produce
wear particles, which create a similar con­
dition. In addition, the fact that the parti­
cles released are significantly smaller than
those associated with standard PE, some
concerns exist over the long­term biologi­
cal reaction to these smaller particles and
their increased surface area. In the case of
metal­on­metal articulations, the unavoid­
able leaching of metal ions represents an
obvious risk.
Synovial Fluid Lubrication
We know today that there is no perma­
nent hydrodynamic state of lubrication in
artificial hip joints. The continuous shifting
between motion and rest and the frequent
generation of one­sided stress usually pre­
vent the formation of a permanent lubri­
cating film of synovial fluid. This makes the
wear resistance of the articulating mate­
rials even more crucial.
A
B
C

Instability
Component impingement can result in a
limited range of motion (ROM). That’s why,
in addition to exact implant positioning,
the technical ROM achieved after implan­
tation plays a crucial role. While large ball
head and cup­liner diameters increase
ROM, they are associated – in the case
of PE and XPE – with an increased volume
of wear particles and in a metal­on­metal
articulation with the possible negative
effects of an elevated level of metal ions
released into the surrounding tissues.
Both mechanisms have been the subject
of intense scientific discussion.
Impingement and dislocation
are a frequent complication
in younger and more active
patients.
Source: Prof. Dr. W. Mittelmeier, Orthopaedic Clinic, Rostock University,
Germany
Hypersensitivity
The incidence of hypersensitivity and al­
lergic reactions to metals is on the rise in
the world’s industrialized countries. The
possible onset of hypersensitive reactions
in patients treated with metal­on­metal
bearings cannot be completely ruled out
in advance. Metal allergies detected post
surgery represents an additional burden
for patients and insurers. Therefore, it has
become even more important to use im­
plant materials that exhibit a biologically
compatible behavior in the body.
BIOLOX ® delta has introduced novel
solutions to these problems.
Source: Prof. Dr. P. Bösch, Orthopaedic Department of the Wiener Neustadt Hospital, Austria
“Melting bone” as a result
of metal ion exposure.
3

4
Tribology and Arthroplasty
Competence in Ceramics
Material Properties
The Strengths of BIOLOX ® delta
Proven High Performance Ceramics
Ceramic ball heads before
sintering – a refined
process ensures reliable
products.
Comprehensive quality
control – 3D measurement
of ball heads
Technology Leader
About 80 percent of all ceramic implants
for hip arthroplasty are manufactured by
CeramTec. Around 4.1 million ball heads
and 700,000 cup liners made of BIOLOX ®
ceramics have been implanted to date (Au­
gust 2007) around the world. The clinical
results in combination with approximately
500 stem and 150 cup systems marketed
by all of the leading implant manufacturers,
have been outstanding. With comprehen­
sive experience in this area for more than
three decades, CeramTec is the world
leader in this technology.
Ceramic components made of BIOLOX ®
owe their superior properties to a unique
material composition, the most modern
production techniques and a multi­stage,
comprehensive system of quality control.
Extreme Hardness
The purest raw materials and a manufac­
turing process that has been refined over
decades ensure the highest degree of
material uniformity, mechanical properties
and perhaps most importantly hardness.
This results in excellent wear resistance.
Exacting Sphericity
A maximum variance from an ideal sphere
of only 5µm ensures that the articulation
design produces the least amount of wear
possible (testing accurancy

No Third-Body Wear
Unsurpassed hardness prevents surface
damage to the articulation by third­body
wear in ceramic­on­ceramic bearings.
Foreign particles are broken down and
extruded without damaging the bearing
surfaces.
No Scratches
Cement particles and surgical instruments
are not able to scratch ceramic surfaces –
an important advantage when using
cement and minimally invasive procedures.
Highest Degree of Biocompatibility
Clinical experience shows no known long­
term adverse reactions to ceramic particles.
Ceramic materials are entirely biologically
inert and exhibit unmatched biocompat­
ibility.
Metal
Excellent Wettability
Hydrogen bonds between ceramic surfaces
and synovial fluid ensure excellent wetta­
bility and the formation of an effective
lubricating film.
Superiority in Extreme Conditions
Polyethylene
Ceramic
Ceramic
Foreign particles that
are harder than the
bearing surface lead to
high levels of wear (left).
Surfaces made of high
performance ceramics
remain largely unchanged
even when
exposed to ceramic
particles (right).
Scratched surfaces
increase abrasion in
cup liners made of
PE, XPE and metal.
Only an unscratched,
smooth surface of the
sort achieved in BIOLOX ®
ceramics enables optimal
wetting, outstanding
lubrication and minimal
wear.
The strong hydrogen
bonds that form between
ceramic surfaces
and synovial fluid give
ceramic materials wetting
properties that are
superior to those of
metal and polyethylene.
5

6
Tribology and Arthroplasty
Competence in Ceramics
Material Properties
The Strengths of BIOLOX ® delta
Molecular Bonding
Metal bonding (left):
irregular electron orbitals
permit the formation
of ions.
Ceramic bonding
(right): tight electron
orbitals rule out ion
formation and chemical
reactions.
Loose Metal Structure
The molecular structures of metal alloys
and ceramic materials are fundamentally
different. In the case of a metal bond,
the electrons orbit the atomic nuclei in
an irregular manner and with relatively
low bonding strength. As a result of this,
metal ions continuously exit this molecular
structure and, in the case of implants, are
absorbed by the surrounding tissues. This
occurrence can result in many different
chemical reactions.
Stable Ceramic Structure
In ceramic molecules, the electrons follow
exactly specified paths or electron orbitals.
The electrons’ bonding strength is very
high, making the molecules themselves
extremely stable. This prevents ion forma­
tion and chemical reactions within the
body.
Atomic nucleus
Electron

An Optimal Composite
The extremely stable ceramic bond virtually
rules out any possibility of plastic deforma­
tion. While this permits the desired degree
of extreme hardness, it also leads to a
relatively high degree of brittleness. How­
ever, given the right material design, one
can achieve both extreme hardness and
strength. Such composite models exist in
nature and in modern technology.
The protective pearl shell
combines hardness and
strength. It consists of hardbrittle
aragonite and very
elastic layers of protein and
chitin.
Hardness and Toughness Combined
Proven Models
Sea snails protect themselves with shells
made of a finely tuned mixture of hard and
brittle aragonite and thin and very elastic
intermediate layers of proteins and chitin.
More than 2000 years ago, blacksmiths
discovered how to combine very hard
high­carbon and ductile low­carbon alloys
to form a superior composite, the legendary
Damascene steel.
Source: stienenDamast, Mönchengladbach, Germany
Source: J.D. Verhoeven, A.H. Pendray, W.E. Dauksch, Journal of Metals,
vol. 50, No. 9, p. 60 (1998)
Damascene steel combines
hard and ductile alloys
to form a highly firm and
resistant material.
7

8
Tribology and Arthroplasty
Competence in Ceramics
Material Properties
The Strengths of BIOLOX ® delta
Intelligent Reinforcement Mechanisms
A Fundamental Difference
Material sciences make a distinction be­
tween fracture strength and fracture
toughness. Fracture strength is the maxi­
mum mechanical stress a material can
withstand without fracturing. Fracture
toughness is the resistance of a material
to the propagation of cracks. Ceramic
materials that have been in use for a
number of years, such as BIOLOX ® forte,
already have a very high fracture strength.
BIOLOX ® delta additionally exhibits an
extremely high fracture toughness. It has
a much higher capacity than other ceramic
materials to resist the onset of cracking
and to arrest the propagation of cracks.
This property is based on two strengthen­
ing mechanisms.
The principle of conversion reinforcement: zirconium
oxide particles act like airbags by absorbing
impacting forces.
Airbag Function
The first strengthening mechanism is de­
rived from the dispersion of tetragonal
zirconium oxide nanoparticles in the mi­
crostructure. These particles, which are
homogenously distributed throughout the
stable aluminum oxide matrix, produce
local pressure peaks in the area of cracks
and thereby counteract their propagation.
Counteracting Crack Formation
The second strengthening mechanism is
the result of in situ formation of platelet­
shaped crystals in the oxide mixture. These
platelets prevent cracking and crack propa­
gation by deflecting the crack path and
neutralizing crack energy. As a result of
these strengthening mechanisms, BIOLOX ®
delta allows implant designers to create
component geometries that were not pos­
sible with previous ceramic materials.
Crack propagation Crack propagation
Aluminum
oxide
Zirconium
oxide
Platelet
The principle of platelet reinforcement: plateletshaped
crystals block the propagation of cracks and
thereby increase overall strength.

More Uniform and Smooth
The material properties of BIOLOX ® ceram­
ics have been continuously improved since
its inception. With a grain size in the nano
range, BIOLOX ® delta achieves a new
dimension of structural uniformity. This
leads to both smoother ceramic surfaces
and reduced wear.
Strength under Peak Stress
The highest degree of material stress in
hard­on­hard bearings occurs in small di­
ameters. Here, the strength of BIOLOX ®
delta offers an extra benefit. In the case of
BIOLOX ® delta, the well proven aluminum
oxide (more than 80 percent by volume)
ensures uncompromising hardness. Addi­
tional ceramic reinforcement elements
ensure the material’s high resistance
against fracture and crack propagation.
Nanocomposite with
Optimized Microstructure
The microstructure of
BIOLOX ® delta: platelets
with crack­stopping
function (1), aluminumoxide
particle (2), zirconium­oxide
particle (3)
3
1 2
2µm
2µm
BIOLOX ® forte (above),
BIOLOX ® delta (below):
significantly smaller
grain size and higher
uniformity make even
smoother surfaces
possible and enhance
the material properties.
9

10
Tribology and Arthroplasty
Competence in Ceramics
Material Properties
The Strengths of BIOLOX ® delta
Long-lasting Strength
Burst stress to ball
head – loads of up to
ten tons are introduced
via the cone (left).
Burst strength comparison:
Burst strength is
the point at which the
component breaks. This
corresponds to a force
of more than 8 tons in
the case of a ball head
made of BIOLOX ® delta
(right).
Improved Properties
The burst strength test is the “acid test”
for ceramic components. The components
are exposed to axial loading until the point
of material failure. Ball heads made of
BIOLOX ® delta (28mm) resist loads of more
than 80 kilonewtons when tested. Larger
ball heads show an even higher burst
strength.
The burst strength of BIOLOX ® delta is con­
siderably higher than that of conventional
8t
BIOLOX ® delta is resistant
to hydrothermal aging.
20 autoclave hours correspond
to 40 years in vivo.
aluminum oxide ceramics. Furthermore,
tests on standard material samples show
that the bending strength of BIOLOX ®
delta is not adversely affected by repeated
autoclave sterilization. While hydrother­
mal instability can occur in objects made
of pure zirconium oxide, such instability
does not arise in the case for BIOLOX ®
delta thanks to the alumina matrix.
This has been confirmed by extensive
testing.
Burst
Burst
stress
stress
(kN)
(kN)
100
80
60
40
20
0
1 2 3 4 5 6 7
BIOLOX ® BIOLOX ® forte BIOLOX ® 0
Number of tests (7 ball heads)
1 2 3 4 5 6 7
BIOLOX
(since 1974) (since 1995)
delta
(since 2004)
® BIOLOX ® forte BIOLOX ® Number of tests (7 ball heads)
(since 1974)
Burst stress (kN)
(since 1995)
delta
(since 2004)
100
80
60
40
20
0
New
1 autoclave hour
1 storage hour
2 autoclave hours
2 storage hours
10 autoclave hours
10 storage hours
20 autoclave hours
20 storage hours

The Strengths of BIOLOX ® delta
• Increased fracture toughness
• Increased fracture strength
• Crack-stopping function
• Excellent biocompatibility
BIOLOX ® delta is clearly superior when it
comes to the following crucial parameters:
grain size, bending strength, and fracture
toughness.
BIOLOX ® – Comparison of Three Generations
BIOLOX ®
(since 1974)
BIOLOX ® forte
(since 1995)
BIOLOX ® delta
(since 2004)
Variable Unit Average Variance Average Variance Average Variance
Al 2O 3 Vol.-% 99.7 0.15 >99.8 0.14 81.6 0.17
ZrO 2 Vol.-% n.a. – n.a. – 17 0.1
Other oxides Vol.-% Rest – Rest n.a. 1.4 0.01
Density g/cm 3 3.95 0.01 3.97 0.00 4.37 0.01
Grain size Al 2O 3 µm 4 023 1.750 0.076 0.560 0.036
4-point bending strength 1) MPa 500 45 631 38 1384 67
E-module GPa 410 1 407 1 358 1
2) Fracture toughness K MPa m Ic
1⁄2 3.0 0.45 3.2 0.4 6.5 0.3
Hardness HV1 GPa 20 – 20 – 19 –
1) Average values measured for BIOLOX ® delta from 2006
2) Fracture toughness refers to the capacity of a material to resist crack propagation; KIc is the corresponding characteristic value.
11

12
Tribology and Arthroplasty
Competence in Ceramics
Material Properties
The Strengths of BIOLOX ® delta
Large Diameters
Enhanced Biomechanical Properties
The advantages of ceramic materials are
especially apparent in large diameters
(≥32mm). Simulator studies show that
the rates of wear remain low despite the
significantly larger friction surfaces, i.e.
significantly lower than those of other
materials. With ceramic components,
surgeons are no longer forced to make a
tradeoff between wear rates and diameter,
and can instead choose the best option for
their patients.
Hip Joint Simulator – Highly Crosslinked Polyethylene
Long-term wear rate after 10 million cycles
Negative Effect of Increased
Metal Head Size
Volume wear rate (mm 3 per million cycles)
12
10
8
6
4
2
0
28mm
Metal femoral
ball head on XPE
36mm
Metal femoral
ball head on XPE
Fisher J, University of Leeds, 2006
Better Tribology
Dramatically reduced wear, expanded
range of motion and increased resistance
to dislocation make this bearing the num­
ber one choice when it comes to functional
improvement, durability and safety. In
contrast to bearings with conventional
and highly crosslinked polyethylene, the
rate of wear does not increase for ceramic­
on­ceramic bearings in the case of larger
diameters. Given that BIOLOX ® delta shows
even lower rates of wear in the simulator
than BIOLOX ® forte, one can expect that
it is superior to all other materials for bea­
rings with large diameters.
Hip Joint Simulator – Highly Crosslinked Polyethylene
Long-term wear rate after 10 million cycles
Positive Effect of Alumina Ceramic
Femoral Ball Head Compared to
Metal Femoral Ball Head
Volume wear rate (mm 3 per million cycles)
12
10
8
6
4
2
0
36mm
Metal femoral
ball head on XPE
36mm
Alumina ceramic
femoral ball head on XPE
Source: Fisher J, University of Leeds (UK), 2006
Fisher J, University of Leeds, 2006

A manageable problem
Occasionally in hip arthroplasty, the acetab­
ular cup cannot be implanted in the ideal
position. Such cases are particularly prone
to subsequent micro­separation whereby
the ball head retracts slightly from the cup
when it is not loaded. With the next step
of the patient, the ball head is pressed back
into its original position and exposed to
considerable edge loading. In hard­on­hard
bearings, this can lead to stripe wear in
particular zones of the femoral head and
on the rim of the cup.
Stripe wear after wear
test under severe microseparation
(2mm). The
zones showing increased
wear are color­coded.
BIOLOX ® delta Minimizes Stripe Wear
1 Prof. Dr. Ian Clarke, Orthopedic Research Center, Loma Linda University, USA
Specific Testing
The materials BIOLOX ® forte and BIOLOX ®
delta (as well as combinations of these
materials) show significant performance
differences in tests designed to simulate
micro­separation in the motion cycle. The
stripe wear was highest in the forte­forte
combination and lowest in the delta­delta
combination. This difference can be seen
in the run­in phase of the first million
cycles and in the following steady state.
While stripe wear has been observed in all
hard­on­hard bearings, it does not repre­
sent a risk in ceramic bearings. “Of all
hard­on­hard wear couples, bearings made
of BIOLOX ® delta are best at resisting the
phenomenon of stripe wear, both on the
femoral and acetabular side.” 1
Wear volume (in mm 3 per million cycles)
5
4
3
2
1
0
BIOLOX ® forte /
BIOLOX ® forte
BIOLOX ® forte /
BIOLOX ® delta
BIOLOX ® delta /
BIOLOX ® forte
Average rate of wear in
the run­in phase (0 to
1 million cycles) and in
the steady state (1 to 5
million cycles)
0 to 1 million cycles
1 to 5 million cycles
BIOLOX ® delta /
BIOLOX ® delta
Prof. Dr. Ian Clarke, Loma Linda University, USA
13

14
Tribology and Arthroplasty
Competence in Ceramics
Material Properties
The Strengths of BIOLOX ® delta
More Options
Available Sizes
New Geometries
The superior material properties of BIOLOX ®
delta permit component geometries that
were not possible with previous ceramics.
Cup liners with thinner wall thickness still
are able to offer increased stability and
safety as they allow the use of ceramic­
on­ceramic bearings in larger diameters.
In contrast to metal and polyethylene,
ceramic bearings with larger diameters
show no significantly increased rates of
wear.
Ball Heads Ø Stem Length Cup Liners Ø Exterior Diameter*
22.2mm s, m, l Not available Not available
28mm s, m, l 28mm 42–70mm
32mm s, m, l, xl 32mm 46–70mm
36mm s, m, l, xl 36mm 50–70mm
40mm s, m, l, xl 40mm 54–70mm
Numerous combination
options:
ball heads and cup liners
of BIOLOX ® delta can be
combined with ceramic
components of the
BIOLOX ® family as well
as with liners of conventional
and highly
crosslinked polyethylene.
* The exterior diameters of the cup liners are adjusted to the interior
diameters of the various cup systems.
Ball Head:
BIOLOX ® delta
Precise Lubrication Clearance
A further advantage to thin­walled ceramic
components results from the material’s
high stiffness. This ensures that the pre­
cisely adjusted lubrication clearance be­
tween the components, which is necessary
for the formation of a lubricating film, is
not compromised by any deformation in
the thin­walled elements.
Sizes and Material Combinations
Ball heads and cup liners made of BIOLOX ®
forte and BIOLOX ® delta can be combined
in bearings. Ball heads made of both mate­
rials can also be combined with cup liners
made of polyethylene and highly crosslinked
polyethylene.
Materialkombinationen BIOLOX ® delta
Insert:
BIOLOX ® delta
BIOLOX ® delta
BIOLOX ® delta
BIOLOX ® forte
BIOLOX ® forte
PE / XPE
BIOLOX ® OPTION

Optimized Revision
The BIOLOX ® OPTION system offers sur­
geons the option of employing ceramic
bearings for revisions in which the stem is
to remain in situ and is largely undamaged.
The titanium sleeve is designed to com­
pensate for the slightly damaged stem
taper by providing a new unused taper for
use with the new ball head. Ceramic ball
heads made of BIOLOX ® delta permit long­
term and safe treatment.
Knee Arthroplasty
The geometry of bearings used in knee
arthroplasty is significantly more complex
than that of the hip joint. The improved
material properties of BIOLOX ® delta have
also made it possible to manufacture safe
ceramic components for such geometries.
This effectively introduces the advantages
of ceramics to the field of knee arthroplasty.
A comprehensive bibliography is
available on our website:
www.biolox.com/delta-reference/de
Disclaimer
This document is intended exclusively for experts in the field, i.e. phy-
sicians in particular, and is expressly not for the information of layper-
sons. The information on the products and / or procedures contained
in this document is of a general nature and does not represent medical
advice or recommendations. Since this information does not constitute
any diagnostic or therapeutic statement with regard to any individual
medical case, individual examination and advising of the respective
patient are absolutely necessary and are not replaced by this document
in whole or in part. The information contained in this document was
Application Diversity
Further Applications
Participating researchers and the product
development experts at CeramTec are hard
at work on the development of new appli­
cations for BIOLOX ® delta. The possibilities
offered by this material open up new
prospects. Components for use in the treat­
ment of the spine, other joints and dental
products are currently in various phases of
development.
gathered and compiled by medical experts and qualified CeramTec em-
ployees to the best of their knowledge. The greatest care was taken to
ensure the accuracy and ease of understanding of the information used
and presented. CeramTec does not assume any liability, however, for
the up-to-dateness, accuracy, completeness or quality of the informati-
on and excludes any liability for tangible or intangible losses that may
be caused by the use of this information.
In the event that this document could be construed as an offer at any
time, such offer shall not be binding in any event and shall require
subsequent confirmation in writing.
15

BIOLOX ®
Ceramics in
Orthopaedics
Germany
in
CeramTec GmbH
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