1. i-Polymers for i-Arthroplasty
New Polymer Technologies for Hip Arthroplasty
Leo Smit
Business Director Implant Solutions
Materials that belong to the body
DSM Biomedical
DSM Biomedical

2. A story about bones, needing assistance…….
• Osteoarthritis (degenerative joint
disease)
• A group of diseases leading to
degeneration of joints (bones and
cartilage)
• Leading to pain, stiffness, cracking of
joints, inflammation
• Some US #’s:
• App 27 million US citizens are affected
• Accounts for 25% of all visits to
primary care physiscians
• 80% of people @ 65 yrs will show
radiographic evidence; 60% will show
symptoms
DSM Biomedical

3. Interventions at all stages of the disease continuum
DSM Biomedical
DSM Nutritional
Products
Early Interventional
Total Joints
Wellness
Population Size
At Risk Critical
Episode Recurrence Advanced
Disease
Disease continuum
DSM Biomedical

4. DSM approaches to joint health
i-flex – a joint health food supplement from DSM Nutritional Products, containing
vitamins, carotenoids and galactolipids mixture that has been demonstrated in vitro to
have protective and even regenerative effects on human cartilage.
DSM is the world’s leading producer of Vitamin E
Easy-XL – a novel family of UHMwPE grades with a
new molecular architecture to
increase crosslinking efficiency
HALS-UH – an Alternative Stabilizer that provides for
stabilization of UHMwPE powder
Bionate® Poly Carbonate Urethane polymers for soft bearing applications and
Early Interventional Arthroplasty.
DSM Biomedical

5. The Final Solution: Total Hip Arthroplasty
One of the largest successes of the medical profession
>2 Million Hip and Knee replacements carried out annually
Multitude of innovations, total hip/knee, uni-knee, hip resurfacing
Many materials being used – polymers, metals, ceramics
DSM Biomedical

6. Total Hip Replacement
DSM Biomedical

7. WEAR : the central theme in Hip Arthroplasty
Picture from Gomez-Barena
Teflon too soft UHMwPE
“Hit by friendly fire” : Macrophage attacks on PE wear particles cause
human biological/physiological responses leading to osteolysis.
Current artificial hip lifetimes are app 10 – 15 years
current demographics ask for more!
DSM Biomedical

8. Demographics make things worse
People are reaching
higher ages,
which is good, yet
people are more obese and/or
our lifestyle is aimed at staying
more active
so the pressure on our joints increases
DSM Biomedical

9. Alternative material approaches…….
DSM Biomedical

10. Materials options compared
UHMwPE MoM CoC
Pros Pros Pros
- Longest clinical history - Low wear - Low wear
- Low wear when XL’d - Large head sizes - Excellent biocompatibility
- Excellent biocompatibility
- Highest clinical usage
Cons Cons Cons
- Oxidative susceptibility - Metal ion release - Fracture is clinical disaster
- Processing steps - Implant noise - High material cost
- High cost of fabrication - Implant noise
DSM Biomedical

11. Crosslinking – THE breakthrough in UHMwPE
Cr
Th
os
e
Co
St
rm
Ma
Pa
Cl
eri
ns
sli
Powder Implant
al
ck
ea
ch
liz
oli
tre
ag
nk
nin
ini
ati
da
atm
ing
ng
on
g
ing
t io
en
n
t
Stryker:
Stryker: Crossfire®
Crossfire®
X3TM
X3TM
Zimmer:
Zimmer: LongevityTM
LongevityTM
ProlongTM
ProlongTM
DePuy:
DePuy: MARATHON
MARATHON
Biomet:
Biomet: ArCom® XLT
ArCom® XLT
S&N:
S&N: XLPE
XLPE
Picture: Zimmer
DSM Biomedical

12. Significant reduction in wear rate
Both in-vitro as well as in-vivo wear
reduced as function of the Radiation Dose
Laboratory and clinical results
1.00
Longevity (Ref. 12)
Conventional (Ref. 12)
Durasul (Ref. 12)
0.75 Conventional (Ref. 12)
Marathon (Ref. 12)
Normalized Wear
Crossfire (Ref. 13)
Duration (Ref. 11)
Gamma-air (Ref 14)
0.50 Eto (Ref 15)
N2 Vac - Lab
Arcom - Lab
Duration - Lab
"Marathon" - Lab
0.25 "Durasul" - Lab
Crossfire - Lab
"Longevity" - Lab
X3 - Lab
0.00
0 20 40 60 80 100
Radiation Dose (kGy)
DSM Biomedical Edge-Loading Wear of Metal-on-Metal and Metal-on-X3® Highly Crosslinked
Polyethylene: Survival of the Fittest
Aiguo Wang, Ph.D., VP, Reconstructive Technologies, Stryker Orthopaedics, Mahwah,
New Jersey, USA.

13. Radicals form new challenge
Macro-radicals are created
during irradiation
Macro-radicals react with oxygen -
causing oxidative degradation of the
bearing material
DSM Biomedical

14. Current radical removal options
Thermal treatment
Remelting OR Annealing
Additional step - time consuming, costs
Loss of mechanical properties
Diffusion into the final Implant Pre-blending with the polymer
Vitamin E stabilization
OR
Pre blended Vitamin E interferes with crosslinking process *
Vitamin E is consumed in the crosslinking process
Material turns yellow
* (Oral, E et al, Biomaterials (2005), 26(33), 6657-6663)
6657-
DSM Biomedical

15. UHMwPE Paradigm
Reduced wear debris Reduced osteolysis
Ideally:
• wear resistance
• oxidation resistance
WEAR
RESISTANCE
• mechanical properties
REAL WORLD so far not
ideal – Wear optimization
MECHANICAL OXIDATIVE causes compromises
PROPERTIES STABILITY
DSM Biomedical
Gomez-Barrena, E et al. Acta Orthopaedica 2008, 79 (6), 832.

16. Alternative stabilizer : HALS
HALS : Hindered Amine Light Stabilizer
No radical scavenging during radiation
no interference with the crosslinking process
Regenerative - Less stabilizer needed
No yellowing (consistent color) because no degradation
components are formed
DSM Biomedical

17. HALS : Crosslinking improvement
Higher crosslink
Vitamin E: higher swell
density for HALS
ratio =lower XL density than for Vitamin E
7.0
Reference stabilized UHMwPE
6.5 500 ppm Vit E
1500 ppm Vit E
6.0 500 ppm HALS-1 • Tested 0.05 and 0.15 wt.% Vitamin E
1500 ppm HALS-1
5.5 versus 0.05 and 0.15 wt.% HALS
Swell ratio (%)
• No significant differences between
5.0 0.05 and 0.15 wt.% HALS
4.5 • No influence type of HALS
4.0
3.5
3.0
2.5 GUR 1020 UHMwPE
2.0
0 20 40 60 80 100 120 140 160
Irradiation dosage (kGy)
DSM Biomedical

18. HALS-UH shows effective stabilization
0.35
Reference
500 ppm Vit E
0.3
1500 ppm Vit E
500 ppm HALS-1
0.25 1500 ppm HALS-1
Delta Carbonyl Index
(FTIR: Abs 1718 cm-1/ 2020 cm-1)
0.2
0.15
0.1
0.05
0 GUR 1020
0 20 40 60 80 100 120 140 160
-0.05
Irradiation dose (kGy)
Change in Carbonyl Index as a result of ageing during 6 weeks at room
temperature shows better stabilization compared to vitamin E
DSM Biomedical

19. Easy-XL™ : better crosslinkable UHMwPE
Incorporatedienes in Hypothesis :
growing PE chain:
Incorporation of diene in UHMWPE will leave a pendant
M+
+Gr unsaturation which is believed to make
ow
Diene
ing
po
crosslinking more efficient.
lym
er
ch
ain
This enables the use of lower radiation doses, so
less radicals stay behind which may potentially
reduce oxidative degradation.
Further by adapting molecular
architecture we
can optimize mechanical properties
DSM Biomedical

20. Easy-XL™ needs significantly less radiation for low wear
Results show that 25 kGy irradiation (i.e. sterilization dose) resulted in a
wear resistance comparable to highly XL materials
Wear Factor versus irradation dosage
4.5
4.0
Wear factor (10-6 mm3/N m)
3.5 Conventional
UHMwPE
3.0 (GUR1020, 1050
and MG003)
2.5 DSM Next
generation
2.0
- 2 (10-6 mm3/N m)
1.5
1.0
- 50 kGy
0.5
0.0
0 20 40 60 80
Irradiation dosage (kGy)
DSM Biomedical Pin on Disk wear measurements.
See Eva Wisse et.al. 4th International UHMWPE Meeting, Turin, 2009

21. Less remaining free radicals with Easy-XL™
For both conventional UH and Easy-XL™ it was shown that 75 kGy radiation
leaves behind 2-3 times higher radical content than 25 kGy
Easy-XL™ crosslinked material has much less residual
radicals!
VNB, 12 C=C/100K C S2825KGY1
25 kGy MG003 M325KGY1
25 kGy
S2875KGY1
75 kGy M375KGY1
75 kGy
EPR intensity [arb.units]
EPR intensity [arb.units]
electron spin resonance (ESR) spectroscopy
325 330 335 340 345 350 325 330 335 340 345 350
Magnetic Field [mT] Magnetic Field [mT]
DSM Biomedical

22. Better Mechanical Properties
30
Optimizing the
25
Molecular Architecture
20 enables us to find a
Stress [MPa]
15 new balance in
3736 - 0kGy
10 mechanical properties.
GUR 1020-0 kGy
5
0
Easy-XL™ is a stronger material:
0 5 10 15 20
- a.o. 30% higher Yield Stress
Strain [%]
DSM Biomedical

23. Conclusion – will we break the paradigm?
HALS-UH and Easy-XL™,
Reduced wear debris Reduced osteolysis
separate or combined,
form a strong vehicle to
break the paradigm,
WEAR
RESISTANCE
creating novel polyethylenes for arthroplasty,
having
better wear resistance,
better mechanical properties
MECHANICAL OXIDATIVE
PROPERTIES STABILITY and
better oxidative stability
all at the same time.
DSM Biomedical

24. Yet…….……….
ALL innovations thus far have been aimed at
increasing the hardness
of the bearing material
This is opposite of what is present in the human body:
Cartilage is much lower in hardness than polyethylene
DSM Biomedical

25. Arthroplasty – real cartilage
DSM Biomedical

26. Arthroplasty – real cartilage
Spongy and Lubricated…..
DSM Biomedical

27. Hypothesis
Increased Compliance (compressibility) and
Lubrication can lead to breakthrough technology
A Bio-mimicking Material
PolyCarbonate Urethanes
Bionate® PCU
DSM Biomedical

28. First Compliant Total Hip Implant
DSM Biomedical www.activeimplants.com

29. Imitating Joints vs Replacing Joints
Cartilage in M/L Direction
UHMWPE
PU
Cartilage in A/P Direction (Bionate 80A)
(Parallel)
Graph compiled b y Active Implants; IMUKA 2010 PolyCarbonate Urethane, A compliant soft bearing material in THA, Emanuele Nocco
Articular cartilage data from middle depth values of human distal femur in Adult Articular Cartilage by MHR Freeman,1974;
UHMWPE Data from Steve Kurtz, PhD, Exponent, Inc.
PU Data from DSM PTG SR = Strain Rate
DSM Biomedical

30. Contact Angle
Average Std. Dev.
Bionate® 80A PCU 76.5 0.5
UHMWPE 104 2.6
PCU Material More
Hydrophilic
All done with distilled water.
DSM Biomedical

31. The effect: Hydroplaning
The lower contact angle
helps to establish a
full fluid film
between the bearing
surfaces, enabling
them to
“hydroplane”
with very low level of
friction. www.activeimplants.com
DSM Biomedical

32. Enabling Technology for Early Intervention
The “body-like” characteristics of PCU’s also make them very likely
candidates for earlier interventions: e.g. direct use against Cartilage
DSM Biomedical www.activeimplants.com

33. Acknowledgements
In 2007 DSM Biomedical initiated a new R&D program to develop
new polyethylene materials for use in Arthroplasty.
Our Team:
Eva Wisse
Nilesh Kukalyekar
Jan Stolk
Rob Janssen
Tim Kidd
Micha Mulders
Harold Smelt
Pieter Gijsman
Bill Fuller
Marc Hendriks
DSM Biomedical

34. THANK YOU
Materials that belong to the body
The description by DSM Biomedical of the characteristics and properties of its products as contained in this presentation is
supported by research and believed to be reliable. It is for general information purposes only, and may not be relied upon
in individual situations. Products are supplied under contract containing detailed product specifications, and the user shall
be exclusively responsible to assess the suitability of the product as specified for any individual application or use.
DSM Biomedical
DSM Biomedical