Argos SpineNews 3

October 2000
News from the world of Spinal surgery and biomechanics
Focus on :
Discover the world
of nanotechnologies
A new bipedicular implant
Etienne-Jules Marey :
the eye of biomechanic
New trends in
computer-assisted surgery
Interview of Pr François
Lavaste - Part 1
ENSAM Biomechanics
Laboratory
ENSAM Biomechanics
Laboratory
T H E O F F I C I A L A R G O S P U B L I C A T I O N

communication
Interview of Professor François Lavaste -
LBM Paris - Part 1
events
Inaugural meeting of ARGOS
Argentina
Expo-Intermedica
7th seminar of spinal biomechanics,
Poros Greece
internet
Web review
science
Discover the fantastic world
of nanotechnologies
evaluation :
technologies
New trends in computer-assisted
surgery
history
Etienne-Jules Marey :
the eye of Biomechanics
focus on
The center for medical robotics
and computer assisted surgery at
UPMC Shadyside and
Carnegie Mellon University
Pittsburg USA
clinical cases
Degenerative spondylolisthesis
associated with lumbar stenosis
Lumbar canal stenosis and instability
technologies
Nobel Prize Winner, Pr Georges Charpak
contribution to medicine 44
39
38
32
30
28
22
20
16
15
15
14
8
TTaabbllee ooff ccoonntteennttss
October 2000
News from the world of Spinal surgery and biomechanics

For more information, see next page and get in touch with your local distributor.
Centre Hospitalier de l’Université de
Montréal
1560 Sherbrooke Est Str.
Montreal (Qc)
CANADA H2L 4M1
Phone (514) 281-6000 #8720
Laboratoire d’imagerie, de vision
et d’intelligence artificielle (LIVIA)
École de technologie supérieure
1100 Notre-dame West Str
Montreal (Qc)
CANADA H3C 1K3
Phone (514) 396-8800 #7675
Biomechanics - biomaterials
research group
École Polytechnique
CP 6079 Succ. Centre-ville
Montreal (Quebec)
CANADA H3C 3A7
Phone (514) 3940-4711 #4198
Industrial collaborations :
GERMANY : Telos
CANADA : Arthrolab, BiOp,
Orthomedic, Zimmer
FRANCE : ARGOS, Eurosurgical, Ceraver
USA : Sofamor Danek,
Proctor and Gamble
Funding :
NSERC, FCAR, FREOM, FCI, FRSQ
University collaborations :
Biomechanics laboratory
of ENSAM (Paris FRANCE)
LIS3D & Hôpital St-Justine (CANADA),
University of Bochum (GERMANY)
Medical
Imaging
2D/3D
digital
imaging
processing,
3D models and
reconstructions,
low radiation
multiplanar imagery
Clinical studies
Diagnostics,
evaluation of
prostheses
and
orthoses
Medical
Imaging
2D/3D
digital
imaging
processing,
3D models and
reconstructions,
low radiation
multiplanar imagery
Clinical studies
Diagnostics,
evaluation of
prostheses
and
orthoses
Biomechanics
Study and modeling of
joint function, pathology,
prosthetic replacement
Biomechanics
Study and modeling of
joint function, pathology,
prosthetic replacement
The Montreal Imaging
and Orthopaedics
Research Laboratory
Research center of CHUM Montreal Canada
Circle4onReadingServiceCard

( )EDITORIAL STAF
Editor in chief
Alexandre Templier, PhD
Production/Art director
Karim Boukarabila
Board of editors
the ARGOS committee
Writer/Translator
Patrick Bertranou, MD
Blake W. Rodgers, MD
Carl Stéphane Parent
Philippe Strauss
Alexandre Templier
Assistant publisher
Carl Stéphane Parent
ARGOS COMITTEES
Communication Committee :
Patrick Bertranou, MD
Philippe Bedat, MD
Henri Costa, MD
Pierre Kehr, MD
Charles-Marc Laager, PhD
Pierre Soete, MD
Training Committee :
Jean-Paul Steib, MD
Jean-Paul Forthomme, MD
Franck Gosset, MD
François Lavaste, PhD
Richard Terracher, MD
Jean-Marc Vital, MD
Evaluation Committee :
Wafa Skalli, PhD
Jacques De Guise, PhD
Michel Dutoit, MD
Alain Graftiaux, MD
Henry Judet, MD
Christian Mazel, MD
Tony Martin, MD
EDITORIAL
HEADQUARTERS
ARGOS
64, rue Tiquetonne
75002 Paris FRANCE
Phone (33) 3 21 21 59 64
Fax (33) 3 21 21 59 70
ARGOS SpineNews circulation:
over 7000 biannual issues
by direct mailing to surgeons
and spine professionals around the world.
Advertising sales:
Please contact
Alexandre Templier at
a.templier@argos-europe.com
Fax +33 (0) 1 42 33 06 62
EEddiittoorriiaall
October 2000 - N°2 ARGOS SpineNews 7
ARGOS Members and Friends,
The first issue of ARGOS SpineNews attempted
to respond to a growing need for communication within
the international community of spinal surgeons, engineers,
researchers, and business people. We hope to produce an
orthopaedic journal for those working in spine-related technologies,
as well as a reader-friendly research newsletter. The ARGOS
Committees and we would like to thank you all for being so
enthusiastic about this Journal. Now the train is on its way,
and we will attempt to make the trip as pleasant as possible.
If you have any requests or suggestions to improve this
journal, please send it to our editorial headquarters.
We will do our best to make this journal Yours.
Before you start on this issue however, let us remind you
that the 5th ARGOS International Symposium in Paris
on January 26, 20001, will accept only 250 registrations.
If you have ever attended this event you know that it has to keep
its original size to preserve what makes it special, so please, don’t
forget to register as soon as possible. If you have never attended,
you definitely have to go! Open-minded collegial discussions
of topics at the forefront of clinical practice and
laboratory research in a friendly atmosphere
are not so frequent these days…
So come and join us as we expand the Spine Network!
Warmest regards.
Alexandre TEMPLIER
ARGOS General Manager
Editor in Chief
Christian MAZEL
ARGOS President

In line with our objective to
encourage dialogue, especially
between surgeons and
bioenginners, we propose, in
this issue, the first part of an
interview that François
Lavaste very kindly granted
us. Can you imagine anyone
better informed than the
director of the LBM himself to
help us to more clearly
understand biomechanics and
the work conducted in the
laboratory that he directs?
Meeting with a fascinating
and fascinated man.
Pr François Lavaste, can you give
us a definition of biomechanics?
Biomechanics is the application of the
laws of mechanics to the study of the
movement of the human body. The
human body is considered to be a
material system in the broadest sense
of the term. A system which contains
solids, deformable bodies, and fluids.
In contrast to the mechanics of mate-
rial systems, we do not work on inert
components since the components in
biomechanics are living and their cha-
racteristics evolve over time. Let’s
take the example of bone tissue: it ages
and presents phases of remodelling as
a function of the stimuli to which it is
submitted. Furthermore, in biomecha-
nics, the same component can present
very different mechanical characteris-
tics from one individual to another.
Biomechanics includes structural
mechanics when studying the skeleton,
fluid mechanics when looking at the
circulation of blood and other body
fluids and thermodynamics when
investigating the process of energy
transformation from inspired oxygen
through the metabolic pathways to
exhaled carbon dioxide.
Thus we study all aspects of the circu-
lation, mechanical control by muscles,
and the physiology of movement.
Regulation systems and psychological
aspects are not taken into account.
Do you think that the science of
biomechanics can be dated to a
specific discovery?
8 ARGOS SpineNews N°2-October 2000
Interview of Pr. François Lava
communication
What is Biomechanics ?

communication
I don’t think so. The first wooden
splints date to antiquity. The use of
mechanical structures to stabilize a
fracture constituted an early applica-
tion of the principles of biomechanics.
These practical procedures were then
gradually enriched by basic science to
finally constitute the discipline now
known as biomechanics.
Middle age wooden external prosthesis
Who were the main people who
contributed to the development
of biomechanics?
The people that I know are mostly
Europeans. Pauwels always seems to be
quoted as the first example of a biome-
chanician, but we should also mention
one of his students, Maquet. Pauwels
was both a surgeon and an engineer. He
started to apply the laws of mechanics
to his surgical practice in the 1930s.
Was he already aware of the
interactions between biomecha-
nics and surgery?
Pauwels had a very mechanical view of
the human skeleton and the body’s
physiologic mechanics. His surgical
preparation was always based on
mechanics.
You also mentioned
one of his students?
Yes, Maquet applied Pauwels’ concepts
to the study of lower extremity move-
ment. He can be considered to have
been trained by Pauwels. These two
pioneers cemented the relationship of
biomechanics and orthopaedics. At the
end of the 19th century, many scien-
tists, such as Marey, were interested in
kinematics, the study of movement.
Their research was based on the crea-
tion of specific devices that were able
to mimic the movements of the upper
limbs and other body parts.
These machines were reminiscent of
those developed by Georges Demeny
(one of the inventors of cinema). Marey,
for example, used this type of appara-
tus, i.e. a photographic chamber contai-
ning mobile systems and shutters to
obtain images every one-tenth of a
second, to study the movements of a
bird’s wings. Braun and Fischer exa-
mined human gait for milittary purpose
by trying to optimize the gait of
Prussian soldiers carrying a load.
And more recently?
I think there was a real revolution after
these early steps. These first people
essentially sowed the seeds of biome-
chanics. The progressive development
of conventional radiography, CT and
MRI certainly contributed to the deve-
lopment of biomechanics. Computers,
by allowing digital simulation greatly
enhanced these measurement modali-
ties and gave rise to biomechanics as
we know today.
Does this mean
that technical progress
led to progress in the field
of biomechanics?
Yes. If we look at electronic orthotic
systems, for example, we realise that
they allowed the quantitative analysis
of gait. Marey only performed a quali-
tative analysis of gait. When we look at
Marey’s images we clearly see the
concepts, but when we use electronic
orthotics, we are able better describe
and quantify the movement.
Apart from bioenginners,
have specialists from other
disciplines contributed to this
developing science?
Clinical correlation of biomechanical
theory has been absolutely vital. For
example, orthopaedic surgeons have
made major contributions to the field
of articular biomechanics.
We must not forget that Maquet and
Pauwels were orthopaedic surgeons.
Vascular surgeons also helped bioen-
ginners to understand circulatory phe-
nomena and create models.
Physiologists, scientists specializing in
the analysis and control of movement,
tended to work with physiatrists, func-
tional rehabilitation specialists.
Can we conclude that there has
always been a link between bio-
mechanics and clinical practice?
Yes, although this link varies according
to the discipline. I think it is very close
in orthopaedics, but not quite as close
in the physiology.
ste : what is biomechanics?
PART

communication
What is the reason for
this difference?
Orthopaedic surgeons are, by nature,
closer to bioenginners, as they treat
problems “with their hands”. Their sur-
gical procedures are very mechanical:
they drill, screw, and ream. They work
like a mechanic on a machine, but ins-
tead of working on an inert part, they
operate on the human body. Drilling a
hole in the wall to make a shelf and
drilling a hole in the tibia to insert a
plate are very concrete procedures.
This is not very different from a mecha-
nic’s work in the industrial context.
Orthopaedic surgeons have very
concrete and pragmatic mentalities.
A history of
Biomechanics
in France
How long have you been
director of the LBM?
I helped found the LBM and have
been the director since it was first crea-
ted. I was director of the ENSAM
materials resistance laboratory in 1969,
and then I was director of the structu-
ral mechanics laboratory, where I star-
ted to work on biomechanics. The
LBM was formed in 1979. Our first
biomechanical work dates back to
1972, at the request of Raymond Roy-
Camille (inventor of the pedicular
screw). One of his students, Gérard
Saillant, who is now head of the
Department of Orthopaedics and Dean
at La Pitié-Salpêtrière, came to see me.
He wanted to know whether I could
conduct mechanical trials on the ver-
tebrae in order to identify the most
resistant region. In 1972, we therefore
studied the behaviour of vertebrae sub-
mitted to mechanical loads inducing
rupture and found that the pedicle was
the region most resistant to rupture.
Raymond Roy-Camille then asked us
to study pedicular screw pull-out
forces. Simultaneously until 1980, we
conducted experimental studies with
Gérard Saillant at the Fer à Moulin
experimental surgery unit (the Pitié-
Salpêtrière dissection unit where
orthopaedic and other surgeons are
able to dissect bodies donated to
science). In 1976, we published an
article on disk and nucleus pulposus
implants.
In a way, this represented the
birth of biomechanics in France.
At the time, the teams led by Joannès
Dimnet were working on analysis of
movement in collaboration with Lyon
hospital departments. I think that
Dimnet had started several years pre-
viously in the field of movement ana-
lysis and then became interested in the
vertebral column. In fact, the two of us
followed fairly parallel courses. We
trained in the same institution, which
explains why we had many points in
common and approached problems
from the same perspective. Joannès
Dimnet was probably one of the first
people to have conducted biomecha-
nical studies in France.
How did LBM start to grow?
The development of the LBM occur-
red in parallel with a postgraduate trai-
ning program, corresponding to a
Diplôme d’Études Approfondies
(DEA) (Postgraduate Diploma) in
Biomechanics, accredited by university
authorities in 1985. It was an option of
one of the specialties of the DEA in
Biological and Medical Engineering of
the Ile-de-France region. We entered
this training program in 1987, to set up
the biomechanics option and the LBM
really started to take off at this time. As
I already mentioned, it started to take
shape in 1979, but really developed in
1985. We took another big step forward
The 2TM experimental apparatus (2micrometric heads) allows experimental study of the behavior
of healthy, damaged and reconstructed vertebral segments.

communication
when Wafa Skalli joined us. We would
not be as large as we are today if it
wasn’t for her. She wrote a PhD thesis
on finite element modelling of the ver-
tebral column. This was one of the first
virtual representations of the vertebral
column and quite rare in 1983. She
then joined our laboratory in 1988 and
greatly contributed to the growth of
digital simulation.
▲ Finite element model of a L3-L4 segment
instrumented with a disc prosthesis
▼ 3D FEA modeling of a knee prosthesis
Was this the beginning of a new
generation of bioenginneers?
Yes absolutely. The development of
digital simulation allowed us to
improve our relations with surgeons,
since it propelled our work beyond the
limits of strictly experimental research.
Clinicians work experimentally with
their hands and we were able to contri-
bute the digital elements of simulation.
Virtual representation of the human
body was an innovation at that time.
Could you explain how you
became interested in biomecha-
nics with your background of
conventional mechanics?
My basic training is in mechanical
engineering. I was trained at ENS
(École Normale Supérieure) in
Cachan. I subsequently acquired tea-
ching and research experience as
director of the materials resistance ana-
lysis laboratory. I then became director
of the structural mechanics laboratory
(a structure is a system of mechanical
components). Raymond Roy-Camille’s
request was very much in line with our
work of mechanical characterization of
materials. There is not a major diffe-
rence between characterizing rupture
of a vertebra and characterizing a
beam in civil engineering, apart from
the nature of the material. Changing
from structural mechanics to osteoarti-
cular mechanics therefore does not
really constitute a change of scientific
direction, but represents a continuous
process. We subsequently developed
much more specialized activities, more
closely related to the human body. This
specialization on the vertebral column
developed very gradually, but in the
beginning, it was not a change of direc-
tion, but simply a natural evolution. We
also used the same approaches to ana-
lyse these problems. We now have
machines which are very specific, but,
in 1972, we broke our first vertebra
with devices designed to break metal-
lic structures, because we did not have
any material specifically adapted to the
human body.
Have you ever suffered
from prejudice on the part
of surgeons?
No, I have encountered more prejudice
from mechanical engineers. In the
beginning, when we were working on
anatomic specimens, it induced more
than a scientific curiosity among my col-
leagues. Some of our colleagues had a
very negative view of our activities, as it
was based on dissection of cadavers. We
also developed models using human tis-
sues in order to conduct mechanical
experiments. We had to crush these ver-
tebrae. The negative perception of our
work almost led to suspension of our
research. Nobody could criticise wor-
king with a concrete or metal test tube,
as they are inert parts, but handling a
component of the human body in a
school of engineering was abnormal!
Do you think that these reactions
were culturally based?
Yes, absolutely. It was perfectly accep-
table to examine cadavers in a dissec-
ting room, but there was something
strange about studying components of
the human body on mechanical test
machines. There was something not
quite right. All of a sudden we were
using machines designed to study inert
materials in order to test components
of the human body. This seemed very
bizarre and unhealthy.
Experimental in-vitro study of the human pelvis
submitted to static lateral loads.
LBM-ENSAM-PSA-Renault)
LBM-ENSAM-CEDIOR

communication
Is this research now fully
accepted?
Yes, but we founded a laboratory spe-
cifically devoted to this field and we
now work in a site dedicated to this
activity. We resolved the problem by
creating the biomechanics laboratory.
Our work was difficult to accept while
we were installed in a conventional
mechanics laboratory, but now this
work is recognized as scientific
research, as it is a CNRS laboratory
(Centre National pour la Recherche
Scientifique) [French National Centre
for Scientific Research] and the contro-
versy has been resolved. This was
never a problem in North America.
This laboratory therefore developed
continuously and I gradually moved
from the field of mechanics of struc-
tures to mechanics of the human body.
All of the specificities of the human
body were gradually introduced, lea-
ding to the development of our various
subspecialities.
You mentioned the United States.
How does the LBM compare with
its American counterparts?
The field of biomechanics developed
almost simultaneously, but Europe pro-
bably had a head start, because I don’t
think that Pauwels had an American
homologue. In fact, the first American
studies were conducted in the 1960s,
and then rapidly developed between
1970 and 1980, while the rapid growth
of biomechanics in Europe occurred
between 1980 and 1990.
Didn’t it occur somewhat later?
Let’s say that this discipline developed
during these years and was gradually
recognized as a science. In France, the
Société de Biomécanique was founded
in the 1970s (François Lavaste was pre-
sident of this association), but this
society was founded by physiologists
and not mechanical engineers, who
joined the society a little later.
The Société de Biomécanique played a
real federating role in the history of this
discipline, at least in France, and
helped to constitute it as a scientific
entity. Its annual congress is now
attended by about 200 people, which
has helped to forge the identity of its
various members. Within this Society
we know that we are all bioengineers:
fluid bioengineers, osteoarticular
bioengineers and physiology of move-
ment specialists.
Study of the mechanical behavior
of a human knee.
Was this the birth of a network
between the various specialties?
A real network was developed, in
which each person found his or her
place. As President of this society, one
of my concerns was to recognize the
activities of each of the members. We
therefore established a file in which
each member indicated his or her
fields of interest. We found that one
scientist tended to work in the field of
muscles, while another worked in the
vascular field and another worked in
the field of sport and movement. This
gave us a clearer vision of biomecha-
nics in France.
You mentioned that the LBM
was created to meet the needs
of orthopaedic surgeons.
Did its creation coincide with the
growth of biomechanics?
The creation of the LBM actually coin-
cided with progress in orthopaedic sur-
gery. Orthopaedic surgeons went loo-
king for mechanical engineers because
they felt that they had something to
offer them. To clearly understand this
progress, it must be remembered that,
before this time, surgeons designed
orthopaedic products purely intuitively.
They tried to communicate their ideas
to a manufacturer who then developed
an industrial product, but the whole
process was based on intuition!
Wasn’t this an empirical
approach?
Yes, very much so, and the result could
only be assessed after the implant had
been installed in the patient. When the
clinician worked in collaboration with
the mechanical engineer, he was able to
add objective elements to his intuition.
The birth of biomechanics therefore
reflected this process and this really
corresponds to the work of Pauwels. He
replaced the purely intuitive process by
an objective rational approach based on
his knowledge of engineering. This led
other surgeons to recognize the impor-
tance of working with mechanical engi-
neers in order to design their products.
Raymond Roy-Camille, who intuitively
thought of stabilizing the vertebral
column by fixation of the pedicles, deci-
ded to collaborate with mechanical
engineers. He wanted to make sure that
his idea was well founded, which is why
he asked us to verify that the pedicles
were the most resistant part of the ver-
tebra. Then, when he asked us to study
screw pull-out, he wanted to know
whether it would be better to anchor
the screws in the cortex of the pedicles
and whether this was the site of best
purchase. This was an opportunity for
mechanical engineers to observe enor-
mous differences and variations from
one tissue to another. In some verte-
brae, the screws could be pulled out by
hand as the tissue was completely
degenerated, while in other vertebrae,
forces of the order of 200 N had to be
applied.

communication
Brief review of the
history of the LBM.
1964 Pr Raymond Roy-Camille invented and used
the first pedicular screw in surgery and established
his relationship with the LBM.
1972 First biomechanical studies in collaboration
with Pr Raymond Roy-Camille and Dr Gérard
Saillant on the mechanical behaviour of lumbar
vertebrae.
1985 The LBM participates in the DEA (specia-
list diploma) on Biological and Medical Engineering
for the Ile-de-France region. Together with the
orthopaedics department of La Pitié-Salpêtrière
hospital, LBM is responsible for the biomechanics
option of this DEA. The ENSAM (École Nationale
Supérieure d’Arts & Métiers) is accredited to deli-
ver this DEA in coordination with the Universities
of Paris XII and Paris XIII.
1988 Important growth of the LBM from this date
on, with a rapid increase in the number of PhD.s
(six to eight new PhD.s per year) and extension of
industrial partnerships. The LBM is transferred to
new premises. Close scientific cooperation develo-
ped between Dr J. Dubousset (St Vincent de Paul
Hospital), Dr G. Duval-Beaupère (INSERM unit
215) and the LBM.
1992 Setting up of international cooperation in
the field of spinal biomechanics with the University
of Vermont in Burlington, USA (Pr Ian Stokes) and
the Ecole Polytechnique in Montréal, Canada (Pr J.
Dansereau, Pr J. De Guise, Pr H. Labelle).
1993 The Board of Directors of the Société de
Biomécanique appoints the director of the LBM as
President of the Société de Biomécanique for a per-
iod of two years, thereby acknowledging the scienti-
fic work accomplished by the LBM in the field of
biomechanics.
1996 The LBM is recognized by the CNRS as an
EP 122 applicant team. In the context of spinal bio-
mechanics research, and particularly the biomecha-
nics of scoliosis, Professor Jean Dubousset joined
the LBM team, thereby reinforcing the develop-
ment of in vivo research.
Did this meeting give you a broader vision
of biomechanics?
It showed us that biomechanics was not exclusively limi-
ted to questions of resistance of materials, but that other
parameters were also involved, especially the variability
of mechanical characteristics, related to age and tissue
degeneration. Parameters that we were not used to
taking into account in our classical mechanical calcula-
tions
Were the two disciplines enriched by this
exchange?
They both obtained an enormous and even fascinating
enrichment. By incorporating alloys, and by slightly modi-
fying them, we can alter the mechanical characteristics of
steel, but not to the same extent as those of bone tissue. It
was at this point that we realised that biomechanics was not
exactly the same thing as mechanics, as all of the parame-
ters are radically transformed by the fact that we are dea-
ling with living matter and not inert matter. ■ CS. Parent
[The second part of this interview will be published in the
next issue of ARGOS SpineNews]
Contact information
If you would like additional information or if you would
like to visit the LBM-ENSAM laboratory, please call:
+33 (0) 1 44 24 63 24, or explore our website:
www.paris.ensam.fr/web/lbm
or contact:
Pr François Lavate - francois.lavaste@paris.ensam.fr
Pr Wafa Skalli - wafa.skallli@paris.ensam.fr
Research office:
Laboratoire de biomécanique
École Nationale Supérieure d’Arts & Métiers
151, boulevard de l’hôpital
75013 Paris FRANCE
Phone: +33 (0) 1 44 24 63 64
Fax: +33 (0) 1 44 24 63 66
Secretary: Vanessa Valminos

The first meeting of the
Argentinean ARGOS
association was held in Buenos
Aires on August 10-12, 2000.
JEAN-PIERRE FARCY, MD of
New York University’s Hospital for
Joint Disease and Maimonides
Medical Center was the guest speaker.
Dr. Farcy is an internationally recogni-
zed expert on the treatment of pedia-
tric and adult deformity.
The conference’s first day was devoted
to lumbar osteotomy for the correction
of post-fusion flatback deformity. The
highlight of the day was a live surgical
demonstration by Dr Farcy and
Dr Carlos Solá from the Hospital
Italiano. This was followed by a lively
group discussion of the indications for,
techniques of, and complications asso-
ciated with these difficult procedures.
The second day was devoted to clinical
case presentations. Diverse opinions
were discussed in a spirit of open-min-
ded collegiality. As is common at scien-
tific conferences, a general consensus
was obtained but unanimity of opinion
was impossible to find.
The international ARGOS framework
has provided an invaluable template
for the growth of this fledgling research
group. We understand that Belgium
has also formed a national ARGOS
chapter and that discussions are pro-
gressing toward an American organi-
zation as well. The long-overdue goal
of a worldwide community of surgeons
and researchers - enriched by local
experience but not bound by regional
prejudice - is becoming an exciting rea-
lity. Lastly, we would like to convey our
appreciation to Euromed for their
generous support of our inaugural
scientific meeting.
Left to right : Mr C. Carballo, Pr JP. Farcy,
Mr H. Segura
Inaugural meeting
of Argos - Argentina
communication
Events

communication
Events
A major event for all health
care professionals was held
March 14-17 at the Parc des
Expositions de Paris Nord.
THIS YEAR, the Hôpital expo and
Intermedica trade shows merged
to form a single show and another four
exhibitions were added to this event:
the salon du laboratoire-Bioexpo (the
most important French life sciences
trade show), Stramed (the biomedical
industry subcontractors trade show)
and Hyprotex (textile hygiene and
processing). These six shows now
constitute the largest health care trade
show in France.
More than 1.000 exhibitors presented
a panorama of their products and most
recent equipment at this show, ranging
from ancillary instruments to complete
operating rooms. Entire synthetic
spines were even available. The larger
companies invested impressive
resources in this show, extending over
an area of 70.000 m2
. Each stand rival-
led the others to catch the visitor’s eye.
After visiting a waterfall, a theatre
stage, and a sportsman in the middle of
a training session, the visitor could stop
and watch an amazing presentation of
the latest developments in robotics,
supported by video interviews with
surgeons. A large number of visitors
were interested in textile processing
systems and restoration devices. A sec-
tion was devoted to emergency and
trauma medicine, allowing the visitor
to examine this equipment in detail.
New technologies were strongly repre-
sented. Many companies presented
their products in medical imaging and
telemedicine augmented by the limit-
less possibilities offered by computers.
Another area of the show was devoted
to the Internet. A Quebec delegation
also attended the show.
The Association Quebecois des
Fabricants de Matériel Médical
(AQFIM - Quebec Association of
Medical Equipment Manufacturers)
came to France to present its members’
latest inventions. Thanks to new tech-
nologies, we were able to participate in
a paediatric cardiology examination
live from Quebec. Mr Jacques
De Guise, associate Pr of the depart-
ment of surgery at the faculty of medi-
cine of the university of Montreal and
Pr in the department of automated pro-
duction engineering in the Laboratoire
d’Imagerie, de Vision et d’Intelligence
Artificielle (LIVIA - Imaging, Vision
and Artificial Intelligence Laboratory)
and Mr L’Hocine Yahia, full Professor,
director of the biomechanics and bio-
materials research group, mechanical
engineering department of the école
polytechnique of Montréal presented
the work of the Laboratoire de
recherche en Imagerie et Orthopédie
(LIO - Imaging and Orthopaedics
Research Laboratory). ■ CS. Parent
Expo-Intermedica
THE PURPOSE OF THIS SEMINAR was to pre-
sent new surgical procedures for the treatment of
spinal diseases, an overview of minimal invasive tech-
niques in spinal surgery, and current theories in bio-
mechanics. Scientists from “Maurice E. Müller”
Institute for Biomechanics at the University of Bern,
Switzerland, and from the Biomechanics Laboratory
of ENSAM (Ecole Nationale Supérieure des Arts &
Métiers) in Paris, France, were present among surgeons from
different countries. Pr Sapkas, who organised this congress
in conjunction with the scientific committee (P. Efstasthiou,
N. Zervakis, M. Kasseta, K. Kateros, G. Kountis, A. Badekas,
N. Bitouni, P. Boscainos, E. Stilianessi, G. Tzagarakis, and V.
Tzortzakis) gave all those in attendance the warmest welcome
in the library of the little port of Poros, located at 50 mn from
Athens by boat. This seminar, which began on Friday June 9th in
the afternoon, and ended on Sunday, June 11th at Noon, was a perfect blend of
high level scientific exchanges, and conviviality. More information on this seminar
can be obtained from Pr George Sapkas (gsapkas1@hol.gr) ■
7
TH seminar of spinal
biomechanics, Poros Greece

www.aaos.org
This is the website of a famous
American Association: the AAOS
(American Academy of Orthopedic
Surgeons).
Unlike the Video Medical Journal
website, the colored interface of the
homepage encourages draws the visi-
tor into the site. A great deal of infor-
mation is available (ranging from publi-
cations to CD-ROMs to videos).
Nothing has been overlooked. One
heading is devoted entirely to patient
commentary. Unfortunately, most of
the site is exclusively reserved for
members of the Academy. The shear
volume of information may be overw-
helming to inexperienced netsurfers,
however.
www.ortho-link.com
The internet is not just a passing craze,
it is everywhere. Today, no company or
association can afford to ignore this
media. Convinced of the importance of
Internet, our American partner,
Ortholink, has taken up the challenge
and developed a simple and effective
website.
The first advantage of this site is that
the designers have wisely avoided
submerging the visitor under tons of
superfluous information. The easy-to-
read home page further facilitates the
use of this site. In contrast to the aus-
terity of so many other websites, the
modern design gives it an attractive
appearance and even inexperienced
netsurfers can easily find their way
around with, as bookmarks present at
the top and bottom of each page guide
the novice.
No matter how attractive the site, it
only has any real value when it pro-
vides services not available with
conventional media. The products mar-
keted by Ortholink are described in
detail. If you are interested in one of
these products and wish to purchase it,
remember that the on-line order form
is protected by a security payment sys-
tem.
www.paris.ensam.fr/web/lbm
We obviously could not devote an
article to the Laboratoire de
BioMécanique without presenting its
website, which is much more than a
simple eMail address and provides a
wealth of information. It is not desi-
gned to present scientific information
for the general public, but it is never-
theless accessible to non-specialists.
The general presentation is a relevant
introduction to the world of biome-
chanics, all to brief, unfortunately.
However, the four research groups
composing the laboratory present their
work in much more detail. You can
read about the various studies, espe-
cially those devoted to the spine. Don’t
skip the other research groups, because
their work is sometimes presented
through animated sequences. The
publications and communications hea-
Web review
Orthopedic surgery appears on the internet in a variety of contexts ranging from academic institutional
websites and websites for commercial ventures to personal webpages for individual surgeons. Educational
material and product information is now avalaible around the clock.
internet
Web review

internet
Web review
ding are particularly interesting. About
thirty doctoral theses are summarized
by abstracts, sometimes accompanied
by surprising illustrations.
Finally, the bilingual interface (French-
English) is clear and practical.
www.expo-marey.com
If you missed the exhibition entitled
Étienne Jules Marey: le mouvement
des lumières, organized by the
Fondation Electricité de France from
13 January to 19 March 2000, then this
site admirably attempts to summarize
the exhibition and provide even more
information about this extraordinary
man.
You will discover or rediscover the
range of Marey’s inventions, each one
more fascinating than the next, from
the cardiograph to the aeroplane as
well as biomechanical processes.
Two types of tours are available: the on-
line exhibition and/or a thematic visit.
We heartily recommend both of these
visits, as they are very complementary.
As you will see, the general presenta-
tion of the site is very attractive and
well adapted to the subject treated.
There is only one drawback: there are
only a few video illustration (of all
things !), which are time-consuming to
download.
www.medecine-tv.com
General public television is already
available by Internet, but Progress-TV
has recently launched the first French-
speaking channel entirely devoted to
medicine. Some sites already present
medical information for the general
public, but medecine-tv is more parti-
cularly designed for health care pro-
fessionals.
You rapidly reach an attractive home-
page, which is clear and easy to use. A
large number of headings are presen-
ted. We must congratulate the desi-
gners, who have succeeded in combi-
ning a user-friendly presentation with
a large volume of information.
Take a look at the magazines with inter-
views, or the various subjects devoted
to surgery, etc. This last heading is par-
ticularly interesting. The main advan-
tage of this site is to exploit the various
possibilities available by Internet, pro-
viding on-line films devoted to the
various medical specialties. A film
about fifteen minutes long is devoted to
spondylolisthesis. This film format is
obviously not up to current standards
and the quality of the images largely
depends on your modem and phone
cable. You must also have installed Real
Player®
software (free and easily down-
loaded).
This interesting initiative nevertheless
deserves your attention.
www.orthopod.demon.co.uk
If you are looking for a video document
and don’t know how to obtain it,
consult the British Video Medical
Journal website.
This site combines the two extensive
video libraries of the British
Orthopaedic Association and the
American Academy of Orthopedic
Surgeons. Almost 200 videos on sub-
jects as varied as the knee, the hands
and the spine, are available.
It is true that the interface is fairly aus-
tere and downloads are sometimes a bit
slow, but you will be able to easily find
your way around this very accessible
site. However, if you happen to find the
object of your desires, you cannot
order it on-line. Instead you will need
to print an order form, fill it in and
return it. ■ CS. Parent
… And don’t forget to consult
the ARGOS website:
www.argos-europe.com

5TH
Internationa
Argos sym
FRIDAY JANUARY 26TH 2001, PARIS - MAISON DES AR
www.argos-europe.com
A spineObviously, we could not keep from alluding
to Stanley Kubrick’s film. The beginning of the
3rd millenium is the start of a new Odyssey for
vertebral column surgeons. New technologies
are playing a greater role in daily surgical prac-
tice. It seems only logical to dedicate this year’s
ARGOS symposium to this evolving interface.
The hardest part of designing the program
was deciding what to discuss and what to
leave out. Thus, instead of discussing proven
techniques such as video-assisted surgery, we
have chosen to concentrate on more eminently
emerging - and perhaps not-yet-proven - techno-
logies. The morning session will be devoted to
imaging developments. We will be joined by
engineers from General Electric, Professor
Christopher Ullrich (neuroradiologist at the
Medical University of South Carolina and
President of the Cervical Spine Research
Argos Secretary : Marjorie SALÉ - Phone +33 (0) 3 21 21 59 64 - Fax +33

l
mposium
RTS & MÉTIERS - 9BIS AV. D’IENA PARIS XVI
odysseySociety), Professor Jacques De Guise (from
Montreal’s Imaging and Orthopaedics Research
Laboratory), and Professor Jean-Claude Dosch
of Strasbourg. Afterwards, we will discuss
progress in intraoperative navigation systems.
While these devices are intellectually enticing,
they have not yet proven their worth in daily
surgery. The Medtronic and Aesculap companies
will present their different processes.
In addition, they have agreed to allow two
members of ARGOS use of their navigation
systems in the operating room. These experi-
menters will tell us about their experience as
novices with these ultra sophisticated systems.
We will have the opportunity to see the poten-
tial, and potential limitations, of these technolo-
gies by viewing a live surgery from the opera-
ting theater at the IMM. In the afternoon
session, we will examine the legal pitfalls for
insuring data security that are incumbent in this
technology. Cegetel, the company who
designed and oversees the French health care
computer network, will share their experiences
with us. The day will conclude with an
investigation of the rapidly multiplying Internet
sites created by orthopaedic surgeons.
Professor Jean-Pierre Farcy will discuss the
possibilities and restrictions on these sites and
Mme. Isabelle Lucas Balloup, attorney “à la cour
de Paris” will temper our enthusiasm by
reviewing the many European statutes
governing this new realm of discourse.
Sadly, we realize that the day will be too short
to examine fully all aspects of this technological
and surgical revolution. We hope instead to illu-
minate this new world, spark a collegial debate
about its evolving role, and begin a dialogue on
the very future of medicine.
The Argos Board: Christian Mazel MD,
Pierre Kehr MD, Jean-Paul Steib MD,
Alain Graftiaux MD, Frank Gosset MD.
(0) 3 21 21 59 70 - marjorie@argos-europe.com

Iron atoms in a copper matrix.
Many Arts et Métiers
engineers and future engineers
accepted this invitation to
participate in a conference-
debate on nanotechnologies at
the Ecole Nationale Supérieure
d’Arts et Métiers in Paris, on
Wednesday 15 March 2000.
André MASSON, Former
President of Angénieux SA and
Founding President of the
nanotechnology club,
presented a convincing paper
on this infinitely small universe
with the participation of Jean
FOURMENTIN-GUILBERT,
President of the
FOURMENTIN-GUILBERT
scientific foundation for the
growth of biology.
NA N O T E C H N O L O G I E S
concern the materials, methods
and processes used to observe and
manufacture products or structures
whose dimensions or acceptable
ranges are of the order of nanometres
(10-9
m), in other words a size
comparable to that of the basic
components of matter (atoms and
molecules). They cover the range of
dimensions from 0.1 to 100
nanometres. Take a millimetre (10-3
m),
divide it by 1000 and you obtain a
micron (10-6
m); divide a micron by
1000 and you obtain a nanometre.
Nanotechnologies have given birth to
nanosciences: these “new frontiers of
the technologically possible”. For
example, they are designed to displace,
manipulate and even assemble atoms.
We often use these technologies in eve-
ryday life, often without being aware of
it. For example, to ensure correct rea-
ding of a compact disc, the drive shaft
must be stable to within 20 to 30 nano-
metres. General public printers are fit-
ted with inkjet print heads, which were
developed by means of processes with
a similar degree of precision.
The prospects for the future are very
attractive, as these disciplines are
going to become an integral part of
computers, medicine, biology, surgery,
etc. Ultraprecision machining will
allow even greater miniaturization and
compactness, thereby increasing the
functional capacity of products. One
possible application would be implan-
table drug delivery systems. It would
even be possible to introduce
transducers and detectors
inside an artery! However, the
complexity and volumes that
can be achieved at the pre-
sent time are still very insuf-
ficient.
Other potential applications are
also very interesting. If scientists could
manipulate atoms one by one, it would
be possible to eliminate all impurities
from matter and create more resistant
products. For example, glass has been
made from silica, but without involving
a fusion step. This experience showed
that the physical properties of the glass
obtained were radically altered. Even
more astounding discoveries can be
expected with very light materials, but
just as resistant as diamonds.
André Masson and Jean Fourmentin-
Guilbert emphasized the importance of
nanotechnologies in tomorrow’s world.
They announced that the President of
the United States, Bill Clinton, has pro-
posed that the budget of 200 million
dollars already devoted to these tech-
nologies be doubled. In Japan, a sum of
500 million dollars is devoted to this
research! ■ CS. Parent
A synthetic self-assembling spherical complex.
Cover caption “Tetramethyladamantane”
(green) is encapsulated by two molecules of a
self-complementary synthetic receptor. An
array of weak intermolecular forces are balan-
ced to produce the assembly in solution. (Red
spheres, oxygen atoms, blue spheres, nitrogen
atoms.)
Discover the fantastic
world of nanotechnologies
and its expected growth at the beginning
of this new millenium
science
Nanotechnologies
A “Buckyball”

Considerable progress has
been made in the field of
spinal surgery in recent years,
and instrumentation as well as
the basic principles of
correction have been enriched
by new ideas (6). Despite this
extraordinary progress, the
modes of vertebral fixation
remain limited to pedicular
screws, and laminar or
pedicular hooks (8), or
sublaminar wires or cables.
Each type of implant has its
own supporters and detractors
and each one has its respective
advantages and disadvantages.
ALL OF THE CURRENTLY avai-
lable implants are unilateral and
only fix the left or right part of the
spine. The Raymond Roy-Camille
pedicular screw is now 35 years old
(11) and is very technically demanding
to insert. Although it ensures solid fixa-
tion of the posterior and anterior parts
of the vertebra, there is always a risk of
pedicular perforation, especially in the
thoracic spine (4). Laminar hooks
require opening of the vertebral canal;
they have an upward or downward
direction of fixation, requiring a dis-
traction or compression force, which
can be neutralized by a posterior lami-
nar (12) or pediculo-transverse clamp.
Wires require repeated opening of the
canal with simple, but not very solid
fixation and do not allows distraction or
compression efforts.
These various aspects led to the idea of
development of a new form of fixation,
which is easy-to-insert without ope-
ning the canal, solid with bilateral
anchoring and without prestressing
during insertion, and allows distrac-
tion-compression and anteroposterior
traction or pushing forces.
Material:
Since the costover-
tebral space is a
virtual space and
is frequently
used to insert
transverse process
hooks and to per-
form pediculo-trans-
verse clamps, it should be
suitable for use in this set-
ting (fig. 1). After removal of
the tip of the transverse pro-
cess, the pedicle can be reached
by passing between the rib and the ver-
tebra. Two bifid plate hooks are placed
in contact with the lateral surfaces of
the pedicles, while the body of the
hooks rests on the base of the trans-
verse process.
A transverse com-
pression link connects
the two implants and
encircles the posterior
laminar arch. This consti-
tutes a lateral clamp, which
grasps the vertebra by its
two pedicles (fig. 2a,2b,2c).
The body of the hook is at an
angle of 90° to the axis of the plate in
order to receive a rod from each side.
The bipedicular implant (BPI) there-
fore constitutes a new method of fixa-
tion, with novel anatomic relations and
lateral purchase. The safety and relia-
bility of this bipedicular vertebral fixa-
tion had to be evaluated.
evaluation
fig. 1
Costo-vertebral space
=
safety zone
fig. 2a
Analysis of a new spinal fixation device
Jean-Paul STEIB, MD,* Emeric GALLARD, MSc Eng,** Laurent BALABAUD, MD* ■
fig. 2c
fig. 2b
* Hôpitaux Universitaires de Strasbourg - ** ENSAM Biomechanics Laboratory

evaluation
Methods:
A biomechanical evaluation was necessary to validate this
new fixation (3, 9). Studies are currently underway on
fresh cadavers in the ENSAM Laboratoire de
Biomécanique (LBM) [Biomechanics Laboratory] in
Paris (7). These studies are designed to assess solidity and
stability (1, 10, 14). Solidity tests initially consist of eva-
luating the resistance of the pedicles to bilateral com-
pression forces (fig. 3). This pedicular resistance is fun-
damental to assess the safety of the implant, as excessive
fragility could threaten the spinal cord. The posterior and
lateral pull-out forces (2, 5) of the bipedicular implant
fixed onto an isolated vertebra are then evaluated (fig. 4).
Stability studies are designed to evaluate the mobility of
the instrumented thoracic spine using two CD instru-
ments, one using standard pedicular hooks, and the other
the bipedicular implant (fig. 5).
In both types of fixation, T11 is fixed onto a platform and
T3 is subjected to various loading modes: flexion-exten-
sion, lateral inclination and axial rotation.
Displacements of the T3, T6, T7 and T8 vertebrae are
measured for each loading and the curves corresponding
to the two types of fixation are compared.
fig. 3
Compression strength
References
1. Abumi K, Panjabi MM, Duranceau J
Biomechanical evaluation of spinal fixation devices:
III. Stability provided by six spinal fixation devices
and interbody bone graft. Spine 1989; 14 (11): 1249-
1255.
2. Berlemann U, Cripton P, Rincon L, Lippuner
K, Schlapfer F - Pull-out strength of pedicle hooks
with fixation screws: influence of screws length and
angulation. Eur. Spine J. 1996; 5:71-73
3. Diop A, Skalli W, Lavaste F - Tests et épreuves
biomécaniques incontournables pour le développe-
ment d’une nouvelle instrumentation rachidienne. In:
Pous, Les instrumentations rachidiennes. Cahiers
d’enseignement de la SOFCOT, 1997: 31-40
4. Doursounian L, Henry P - Vissage pédiculaire.
In: Pous, Les instrumentations rachidiennes. Cahiers
5. Gayet LE, Muller A, Pries P, Duport G,
Bertheau D, Lafarie MC - Etude de la résistance à
la traction de l’arc vertébral postérieur thoracique.
Rachis 1998 ; 10(1): 19-26
6. Karger G, Steib J.-P, Roussouly P, Chopin D,
Roy C, Dimnet J, Mazel Ch, Marnay T, Dimeglio A
Les “nouveaux” systèmes d’instrumentation rachi-
dienne postérieure. In: Pous, Les instrumentations
rachidiennes. Cahiers d’enseignement de la SOF-
COT, 1997: 121-128
7. Lavaste F - Biomécanique et ostéosynthèse du
rachis. Cahiers d’enseignement de la SOFCOT.
Conférences d’enseignement 1997: 121-145
8. Milon E - Crochets pédiculaires, laminaires et
transversaires. Du Harrington au Cotrel-Dubousset.
In: Pous, Les instrumentations rachidiennes. Cahiers
9. Panjabi MM - Biomechanical evaluation of spi-
nal fixation devices: I. A conceptual framework.
Spine 1988; 13 (10): 1129-1134.
fig. 4
Pull-out strength
lateral pull-out force
posterior pull-out force
F F

evaluation
Traditional CD construct BPI construct
figure 5
Discussion:
This implant allows pedicular anchoring without opening
the canal and without destabilizing the spine. Sacrifice
of the tip of the transverse process appears to have negli-
gible consequences. This device can be safely implanted
(13) in an avascular space devoid of any nervous struc-
tures. Unlike pedicule screws, this technique is not asso-
ciated with a difficult learning curve and the possibility
of accidental and unidentified perforation of the vertebral
canal with its potentially serious consequences. The BPI
is not incompatible with laminectomy if the pedicles are
preserved and are in a good condition. There is no spe-
cific direction of use (neutral implant), in contrast with
the currently available hooks. Its action and excellent
purchase are very useful for correction of deformities by
rod rotation or in situ contouring. Spatial manipulation
of the vertebrae should be facilitated, especially in the
horizontal plane, which should primarily allow effective
correction of rotation.
References
10. Panjabi MM, Abumi K, Duranceau J, Crisco JJ
Biomechanical evaluation of spinal fixation devices:
II. Stability provided by eight internal fixation
devices. Spine 1988; 13 (10): 1135-1140.
11. Roy-Camille R, Garcon P, Begue Th
Techniques chirurgicales. Etude biomécanique de
l’ancrage des vis pédiculaires dorsales et lombaires.
7èmes journées de la Pitié-Salpétrières 1990: 29-35
12. Tencer AF, Self J, Allen BL, Drummond D
Design and evaluation of a posterior laminar clamp
spinal fixation system. Spine 1991; 16(8): 910-918
13. Thanapipatsiri S, Chan DPK - Safety of thora-
cic transverse process fixation: an anatomical study.
J. Spinal Dis. 1996 ; 9 (4):294-298
14. Wilke HJ, Wenger K, Claes L - Testing criteria
for spinal implants: recommendations for the stan-
dardization of in vitro stability testing of spinal
implants. Eur. Spine J. 1998; 7:148-154
T11
T7
T3
Z
X Y
Z
X Y
T11
T7
T3
fixation of T11
Application of loads
in the three planes
on T3
Measurement
of the relative 3D motions
between T6 and T8
Standard
hooks
Standard
hooks
Standard
hooks
bipedicular
implant
bipedicular
implant
Standard
hooks
Standard
hooks
Cross link
Cross link
Conclusion:
This new type of implant needs to be tested in in vivo clinical
situations, but the preliminary results are promising and suggest
a multitude of applications, not only for fixation and correction
of vertebral deformities, but also for fixation of the traumatic,
tumoral or degenerative spine. Improvements will be made
depending on the results of ongoing trials. ■

The year 2000 is the year of
new technologies. The Internet
is developing at an exponential
rate, and new technologies,
only recently embryonic, are
emerging nearly full-grown.
SURGICAL navigation or “stereo-
taxis”, first developed in the 1980s,
in the field of neurosurgery, has now
been extended to other specialties,
especially orthopaedic surgery. Since
the end of the 1980s, pedicular align-
ment systems for spinal surgery have
been developed according to
various principles, but
always with the same
objective:
spatial
guidance of a high-
risk surgical procedure,
using medical imaging and 3D locali-
zation systems, in order to avoid
damage to particularly fragile struc-
tures such as nerve roots or dura mater.
Then, in the 1990s, navigation systems
were developed in the field of knee
surgery and the objective, in this
context, was to improve the positioning
of femoral and tibial implants during
total knee arthroplasties. Other stereo-
tactic applications in orthopaedic sur-
gery, such as knee ligament recons-
truction, or insertion of acetabular
implants, were also developed. Several
research centers all over the world are
currently working in the field of com-
puter-assisted orthopaedic surgery,
including the Laboratoire d’Imagerie
et Orthopédie (LIO) [Imaging and
Orthopaedics Research Laboratory] in
Montréal (Quebec), the TIM-C labo-
ratory of Joseph Fourier University in
Grenoble (France), and the UPMC
Shadyside Hospital Center for
Orthopedic Research in
P i t t s b u r g h ,
Pennsylvania
(USA).
Although
these technolo-
gies, grouped under the generic term
of “surgical navigation”, are very useful
for orthopaedic surgeons wishing to
ensure a spatially safe and reliable
procedure, they do not provide
any information for the choice of
procedure, and do not allow retros-
pective evaluation of the efficacy of the
procedure chosen. In addition, they are
purely intraoperative technologies and
have offered little advantage to the pre-
and postoperative phases of patient
care.
In spinal surgery and knee surgery,
medical images (x-rays, MRI, CT, etc.)
are most of time used as qualitative
sources of information, and very few
tools provide surgeons and radiologists
with rapid, reproducible and precise
measurements of morphological and
functional parameters. These measu-
rements would have a three-fold value:
to provide surgeons with quantitative
objectives that can be used during the
operation (with or
without surgical
navigation), to
verify the
imme-
diate
postopera-
tive result obtained in terms of the
desired adjustments and to follow the
course of morphological and functional
parameters over time in relation to the
clinical results obtained.
Noninvasive measuring modules,
based on analysis of standard medical
imaging and/or direct measurements,
linked to a clinical database, would
provide orthopaedic surgeons with a
global quantitative vision of their
patient’s morphology, posture and joint
mobility. This information, accessible
to a given surgeon for all of his patients,
would enable the surgeon to gain
maximum benefit from his everyday
experience, and beyond that, to share
this experience with his peers on the
basis of objective measurements.
The locomotor apparatus is particularly
suitable for this type of approach, as it
is submitted to considerable cyclical
mechanical loads related to the
New trends in computer
technologies
Computer-assisted surgery

communication
Computer-assisted surgery
patient’s morphology and posture. The range and type of
joint movements are also very important factors in bio-
mechanical load distribution, and consequently in the
patient’s postoperative outcome. Measurement of the
postural and kinematics parameters of the locomotor
apparatus therefore has an important place in the choice
of operative strategy and analysis of the postoperative
course in orthopaedic surgery, but many sources of infor-
mation, such as conventional radiography, are currently
not used to their full advantage. ■ A. Templier
From leonardo Da Vinci sketches
to 3D medical imaging.
assisted surgery
Surgiview®
:
first surgeons,
then tools…
THE SURGIVIEW®
company was created in April
2000 in order to develop a full range of computer-
assisted diagnostic, surgical and follow-up tools.
Combining the needs and skills of orthopaedic spe-
cialists, orthopaedic surgeons, and also biomechanical
and medical imaging scientists and industrial partners,
SurgiView®
, in the context of an Eureka project
(∑ 2288 Medac), intends to provide surgeons, over the
next two years, with a complete range of software pro-
ducts and equipment designed for preoperative and
postoperative assessment and navigation in ortho-
paedic surgery. The current official partners of this
project are:
- Laboratoire de Biomécanique de l’Ecole Nationale Supérieure
d’Arts & Métiers, Paris (France)
- Laboratoire d’Imagerie et d’Orthopédie, Montréal (Quebec)
- Association ARGOS (international Association of Research
Groups for spinal OsteoSynthesis), Paris (France)
- Zebris, Tübingen (Germany)
- IVS, Chemnitz (Germany)
- The Eurosurgical and Tornier companies.
The first module proposed by SurgiView®
, composed
of SpineView®
1.0 software and the clinical database,
is currently under investigation in French clinical cen-
ters participating in the project:
- Institut Mutualiste Montsouris – Paris (Dr Mazel),
- Hôpital Hôtel Dieu – Nantes (Prof. Passuti, Dr Delecrin),
- Hôpital Pitié – Paris (Prof. Saillant, Prof. Lazennec),
- Hôpital Beaujon – Paris (Prof. Guigui),
- Hôpital Tripode – Bordeaux (Prof. Vital).
A progress report of these studies will be presented
regularly in your ARGOS SpineNews journal.
Computer-assisted imaging of coronary arterial flow.

“The hope of reaching
the truth is sufficient for those
who pursue science through
all their efforts:
the contemplation of the laws
of nature has provided great
and noble enjoyment to those
who have discovered them”.
Etienne-Jules Marey (1830-1904)
WHAT DO biomechanics, bird-
watching and a good film have
in common? Nothing at first sight, but
let us look more closely at the work of
Etienne-Jules Marey.
Born in Beaune (France) in 1830
(where a museum is devoted to his life
and work), this Burgundian, from a
humble background, remains one of
the major figures of 19th century
science. He was simultaneously a doc-
tor, physiologist, clinical pathologist,
professor at the College de France and
a member of the French Academy of
Medicine. He was also responsible for
a multitude of discoveries with appli-
cations from medicine and physiology
to aviation, cinema and photography.
The majority of his career was devoted
to the development of graphic methods
to record physiological activity. He
conducted some remarkable studies on
blood circulation and cardiac mecha-
nics, but his insatiable curiosity also led
him to investigate many other areas of
locomotion from analysis of the flight of
birds to a detailed description of
human gait. This movement-fascinated
scientist was largely forgotten after his
death but his legacy studies, drawings,
graphs, photography, and films (the
first films in the history of cinema) have
recently begun to receive their long-
overdue attention as scientific disco-
veries and magnificent works of art.
At the end of the last century, this
French physician-physiologist was the
first to analyse movement in detail as
well as measure it and rigorously
reproduce it.
“This approach constitutes one of the
foundations of modern orthopaedics”
according to another important figure
of biomechanics, Johannes Dimnet,
former director of the Laboratoire de
Biomécanique du Mouvement
(Biomechanics of Movement
Laboratory) at Claude Bernard
University in Lyon (France).
Photography played an essential role in
Marey’s research. Using this process,
he developed chronophotography in
1892. With this process, biomechanics
took a giant step forward. His invention
“the photograph gun” was able to
break down any movement into its
components by successive views taken
at regular intervals over time.
“The photograph gun”
By taking series of twelve images per
second, Marey was able to describe, for
the first time, the sequence of visible
movements of a walking man, but his
process was unable to cross the barrier
of the skin to observe joint movements.
Many photographs were taken with an
almost cubical box with sides measu-
ring about thirty centimetres. Although
developed in 1890, they already dis-
played all of the principles of the
camera, as subsequently defined by the
Lumière brothers. It included an
impression frame and a spring motor.
He also used celluloid films, which
stopped intermittently in front of the
focal point of the lens.
“The cubical box”
In 1961, the French Cinémathèque
acquired about 400 letters written by
Etienne-Jules Marey between 1881
and 1894 to his assistant Georges
Etienne-Jules
Marey
The eye of Biomechanics
history
Etienne-Jules Marey

history
Etienne-Jules Marey
Demeny (now recognized as the real
inventor of cinema). This very valuable
correspondence is stored in the Film
Library, and has been indexes with a
number of letters found in other
archives. This collection also includes
about sixty unpublished letters from
the period 1877-1904. In particular,
this documentation provides a precise
description of the scientific programme
developed by Marey and Demeny at
the Parc des Princes physiology station.
It was in this now mythical place that
the two scientists worked to develop
their various chronophotographic
devices. A window into the scientific
world at the end of the 19th century,
this collection also reveals the private
side of Marey, especially the
Neopolitan holidays he so enjoyed.
EJ. Marey working in his garden
As a pure scientist, Marey refused to
market his process, which was rapidly
taken up by his contemporaries…
Louis Lumière improved this appara-
tus, then patented the process in
1895. ■
THE PURPOSE of The International Society for the Study of the Lumbar
Spine, a non-profit organization founded in 1974, is to bring together
those individuals throughout the world, who, by their contributions and acti-
vities both in the area of research and clinical study, have, or are indicating
interest in the lumbar spine in health and in disease. Its further purpose is
to serve as a forum for the exchange of information of both an investigative
and clinical nature which relates to low back pain and disability.
The International Society for the Study of the Lumbar Spine has established
a Research Fellowship to promote and extend research activities into the cause
and cure of low back pain. The fellowship is awarded annually based upon the
merits of the applicant, as judged by the Fellowship Committee of the Society.
Currently, a stipend of $15,000.00 US. will be granted to the recipient.
A prospective applicant should have completed formal training in a medical
or allied specialty and should be involved in an investigation of a specific pro-
blem which would be furthered by travel to a location other than his own. An
applicant should be sponsored by a member, or must be a member of The
International Society for the Study of the Lumbar Spine.
The competition is open to all qualified investigators who may apply singly
or as representative of a group. Application is to be made by a letter to a
Committee, specifying the details of the topic to be pursued, the location to
which the fellow would travel to further his study, and the expectations ari-
sing from the venture. Along with the letter of application, a prospective fel-
low should provide a Curriculum Vitae for each proposed investigator and a
statement of sponsorship of the applicant from a member of the Society, as
well as a letter from the Institution the applicant intends to visit confirming
their acceptance of your visit. Also please include the Curriculum Vitae of the
researcher you will visit. Four copies of each should be submitted.
Applications for the 2001 competition must be received by March 1, 2001.
The Committee will announce its selection shortly after this date. The reci-
pient of this award should be prepared to present a report of his efforts to the
2002 annual meeting in Cleveland, OH, USA, May 14-18th. ■
Applications should be submitted to The International Society for the Study of the Lumbar
Spine Sunnybrook and Women’s College Hospital Science Center - 2075 Bayview Avenue,
Room MG 323, Toronto, Canada, M4N 3M5
Phone 416-480-4833 - Fax 416-480-6055
eMail: Shirley.Fitzgerald@swchsc.on.ca
Fencing motion analysis

Closing the loop in surgical
practice: ssing computer
assisted surgical tools to
enable continuous process
improvement in healthcare
The Centers for Medical Robotics and
Computer Assisted Surgery (MRCAS)
establish a collaboration between the
sister labs at UPMC Shadyside
Hospital and Carnegie Mellon
University’s Robotics Institute. The
MRCAS program is helping to take
orthopaedics and other surgical sub-
specialties into the 21st century. This
unique program combines robotics,
engineering and computer science to
assist physicians in the planning, simu-
lation and performance of surgery as
well as in measurements of postopera-
tive outcomes. The goal of the Centers
is to foster the application of these
enabling technologies within all areas
of medicine and surgery with the initial
primary focus in orthopaedics.
The success of the program is founded
on the tight integration in three main
areas: (I) clinical programs; (II)
research and development into the
“surgical toolbox of the future” and the
next generation of more accurate and
less invasive computer-based surgical
tools; and (III) developing metrics
and measuring patient outcomes
through a Total Joint Registry.
The MRCAS program relies on institu-
tional and regional strengths in existing
clinical programs and expertise in the
areas of computer science, robotics and
healthcare and provides the focus of
activity that integrates high quality cli-
nical practice and the research and
development of new innovative tech-
nologies. These tools have the potential
to help our patients by making proce-
dures less invasive and more accurate
and also by directly relating patient out-
comes to measurements of surgical
technique - in essence “closing the
loop” in surgical practice. This com-
prehensive approach will improve
patient outcomes in a cost-effective
manner by enabling continuous process
improvement, immediately and in the
future.
What is Medical Robotics and
Computer Assisted Surgery?
Medical robotics and computer assisted
surgical technologies span the broad
areas of science and engineering to
create intelligent tools that can be
applied to clinical practice. Robotic
technologies, navigation systems and
computer assisted tools can improve
existing clinical procedures as well as
provide innovative new approaches to
clinical problems. A new breed of
computer-based devices presents sur-
The center for medical
robotics and computer
assisted surgery
at UPMC Shadyside and Carnegie Mellon University
A. DiGioia, B. Jaramaz, T. Levison, J. Moody, C. Nikou, R. LaBarca, P. Muir & F. Picard ■
focus on
The Robotics Institute
fig. 1 - Hip replacement surgery using HipNav: Optical localizer tracks the position of bones and
tool. Information is displayed on the TV monitor.

focus on
geons with robust, clinically practical
tools that can do much to augment the
physician’s skill while reducing the
expense of healthcare. Moreover, these
tools can be used to directly relate mea-
surable surgical practice to patients’
outcomes enabling continuous process
improvement in healthcare-reducing
costs by ensuring quality.
In addition to the ongoing work within
the Robotics Institute and UPMC
Shadyside, MRCAS draws upon addi-
tional personnel and resources from
departments within Carnegie Mellon
University such as Civil Engineering,
Biomedical Engineering, and
Computer Science. MRCAS has three
primary goals:
1- perform application-oriented
research aimed at addressing real life
clinical needs.
2 - promote collaboration between
physicians and researchers.
3 - raise the awareness and support
for robotics and computer assisted
techniques within medicine through
an active educational program.
Some of the technology already exists
to address these clinical needs; howe-
ver, the integration of the constitutive
parts is often lacking. The program
brings together the diverse areas that
are necessary to address these pro-
blems.
One example and direct result of the
interdisciplinary collaboration fostered
by MRCAS is the unique image guided
surgical navigation system called Hip
Nav (for Hip Navigation System) that
has been developed to accurately mea-
sure and guide alignment of implants
during total hip replacement surgery.
HipNav has three components. The
first component is a preoperative plan-
ner and simulator in which the surgeon
can pick the appropriate implant size
and optimal position of the femoral and
acetabular components given the
patient’s specific anatomy. The second
component is a range of motion simu-
lator that displays and animates the
range of motion of the hip and impin-
gement conditions for any position of
the patient’s leg. The range of motion
simulator permits the surgeon to opti-
mize the position of the implants in
order to reduce the chance of impin-
gement and dislocation for any indivi-
dual patient. (fig. 2)
fig. 2 - Surgical planner and Range of motion
simulator for total hip replacement: Limits of
leg motion are interactively animated for selec-
ted implants and leg motion paths.
The third component is an intraopera-
tive navigational system then allows
the surgeon to measure and accurately
place the implant in this “ideal” posi-
tion. The expectation is that proper
implant alignment will not only reduce
the risk of dislocation, but will improve
overall hip mechanics and reduce the
chance of longer term problems like
the generation of wear debris due to
impingement. In addition, these tech-
nologies will permit the development
of minimally invasive surgical tech-
niques, which will improve the short
and long-term outcomes of our patients
(fig. 1).
In April of 1997, we began a clinical
trial using HipNav. The clinical infor-
mation that we are collecting has been
very enlightening and provided mea-
surements which surgeons never had
available before. One of the most
important contributions of HipNav
and other computer-assisted technolo-
gies is providing surgeons and clinical
researchers with an accurate intraope-
rative measurement tool. For instance,
with HipNav we can for the first time
intraoperatively track (in real time) the
movement of the patient’s bony ana-
tomy during all phases of surgery.
Furthermore, we can measure the final
position of the implants. These measu-
rements will permit us to directly
relate surgical technique to patient out-
comes. HipNav technology has also
enabled the development of less inva-
sive surgical techniques while impro-
ving accuracy.
Our program is at the forefront of seve-
ral other areas of active research and
development that we expect to directly
impact surgical practice in the near
future. We have developed, demonstra-
ted and hope to soon clinically use an
image overlay system which permits the
display of medical images on the patient
during surgery that in essence gives the
surgeon “x-ray vision” (fig. 3a, 3b).
fig. 3a: Image overlay visualization system-
giving the surgeon “X-ray vision”
fig. 3b - Image overlay system displays medical
images and preoperative plans overlaid on the
patient. In this case, the surgeon can “see
through” the patient permitting display of a
pelvic CT and planned acetabular implant
orientation.
We have also extended the enabling
techniques used in HipNav to surgical
navigation around the knee. KneeNav

focus on
will be used clinically in the coming
months to assist surgeons in perfor-
ming total knee replacement (TKR)
and anterior cruciate ligament recons-
tructions (ACL).
We began a collaborative program
with Dr Freddie Fu (Chairman of the
Orthopaedic Department at the
University of Pittsburgh) to develop an
ACL/PCL surgical navigation module
for KneeNav. A randomized study on
sawbones was already performed to
compare the accuracy of KneeNav with
a traditional arthroscopic technique.
KneeNav system improved reliability
and repeatability of ACL reconstruc-
tion. Surgical error was significantly
less important using the computer
assisted system. About four computer-
assisted procedures were sufficient for
experienced surgeons involved in the
experiment to become proficient with
the technique. This computer-assisted
ACL navigation system has the poten-
tial to reduce surgical error and varia-
tion from optimal graft alignment.
Subsequent studies will focus on
improved models and clinical use as a
measurement tool first and then as a
complete navigation system.
fig. 4 - Sagittal cut plane of the virtual ACL.
In parallel, a KneeNav-TKR system
being developed at UPMC Shadyside
Hospital. During alignment of the cut-
ting jigs the surgeon views a video
monitor that displayed the current
position of the traditional guides rela-
tive to the femur and tibia. The sur-
geon slides a pre-calibrated “plate-
probe” tracker, into the usual saw slot
of the mechanical guides. A video
monitor provides intra-operative mea-
surements of alignment and guidance
information. Specific user interfaces
represent predefined mechanical axes,
which are the surgical frame of refe-
rence and serve for cutting guide
orientations.
The surgeons are then able to measure
their surgical practice, and also ideally
orient the cutting guides relative to the
mechanical axes. Bone cuts are done in
the usual manner using an oscillating
saw, and the surgeon can then check the
cutting plane using the same plate-probe.
The implants are then secured, and the
surgeon verifies soft tissue balancing
and alignment using specific interfaces
simultaneously displaying relative
bone movement. First experiments
proved feasibility, repeatability and
reliability of this computer-assisted
knee system. An IRB (Institutional
Review Board) approval has been
granted and will allow us to assess the
system in clinical trial. Several studies
are already scheduled to use KneeNav
as a measurement tool or compare it to
other current commercial product (as
Orthopilot system).
fig. 5 - KneeNav-TKR. The TV monitor dis-
plays simultaneously bones, mechanical axes
overlaid and cut orientation.
We are also developing robotic mani-
pulators and microelectromechanical
systems (MEMS) which will embody
the next generation of surgical tools
and measurement devices. These tools
will eventually permit more accurate
and less invasive surgical procedures
all to the benefit of our patients.
Measuring Patient Outcomes:
The Total Joint Registry Improvements
in current medical procedures require
the evaluation of clinical results and
patient outcomes. The costs of new
technologies must be weighed against
the benefits, potential savings and
improved clinical outcomes, especially
in today’s healthcare environment.
The Total Joint Registry has developed
a database to evaluate clinical and
patient-perceived outcomes following
total joint replacement surgery.
The Total Joint Registry includes a
general clinical database to facilitate
the evaluation of joint reconstruction
procedures. Candidates for the
Registry include any patients under-
going total hip or total knee replace-
ment surgery. Patients are evaluated
preoperatively, as well as postoperati-
vely at 3 months, 6 months, 1 year and
annually thereafter. The information is
collected prospectively and by an inde-
pendent observer and includes the
Harris Hip Score or Knee Society
Score, the SF-36 Health Status Survey,
and a Hip/Knee Outcomes Data
Collection Instrument. In addition to
these clinical and patient reported
outcome measures, the Registry data
can be used to track real costs (as oppo-
sed to hospital charges) of total joint
replacement surgery, as well as costs
associated with the treatment of com-
plications and required revision sur-
gery.
The Total Joint Registry will provide a
pool of data for comparison and deter-
mination of clinical outcomes from sur-
geons’ and patients’ perspectives. This
outcomes information can also be used
to develop a mechanism to evaluate
new surgical interventions and tech-
nologies in total hip and total knee
arthroplasty, in terms of patient out-
comes, surgical outcomes and cost
effectiveness. The goal of the Total
Joint Registry and our clinical out-
comes project is to develop a resource

focus on
upon which surgeons can draw to assist
them in the clinical decision making
process. This will promote increased
accuracy and efficiency in orthopaedic
practice improving patient outcomes
through continuous process improve-
ment ensuring quality patient care.
To date, the Total Joint Registry has
enrolled over 330 patients. In addition,
the Registry will be open to all patients
from interested orthopaedic surgeons
in the Pittsburgh area, thus increasing
the pool of patient information avai-
lable for clinical research studies.
Ultimately, this standardized outcomes
database will permit comparison of
patient outcomes from multiple sur-
geons and medical centers.
A New Industrial Base
We are entering an era of increased
potential for the commercialization of
computer assisted surgical tools and
related technologies.
If we are to realize the potential for
improving patients’ outcomes, the
commercialization of these emerging
technologies will be an important step
towards making these tools available to
a broader surgical audience and in turn
help more patients.
This step will be important to the
longer term sustainability of the
entire area of computer integrated
surgery and holds the potential to
establish Western Pennsylvania as a
worldwide leader not only in
research and development, but also
in transferring technology to the
commercial sector resulting in a new
industrial base for Pittsburgh and
Western Pennsylvania. Towards these
ends, CASurgica, Inc. was recently
established as the commercial limb of
the MRCAS program with the goal to
commercialize the next generation of
Computer Assisted Surgical tools
and technologies.
The Impact on Healthcare
Delivery in Pittsburgh and the
Nation
Our program is positioned to establish
an example for the country on how
continuous process improvement and
computer assisted tools could result in
high quality, cost-effective healthcare
provided in a patient friendly environ-
ment. In addition, our program has the
opportunity to be both a regional and
global authoritative body concerning
clinical care and research in these
areas. Clinical and basic science
research funding would be increased
because of the focus on solving real cli-
nical problems. Finally, the opportuni-
ties in technology transfer and partne-
ring with commercial entities would
lead to establishment of a new indus-
trial base for Pittsburgh and Western
Pennsylvania.
Our team effort, through the existing
interdisciplinary MRCAS clinical and
research programs and educational
activities is uniquely positioned to
achieve all of these goals making the
Pittsburgh region an international lea-
der in the areas of medical robotics,
surgical navigation and computer assis-
ted surgical technologies and a clinical
center of excellence that will be known
locally, nationally and internationally.
Contact Information:
Upcoming MRCAS Related
Educational Activities
Educational activities play a significant
role in raising awareness of computer
assisted surgical technologies, and
exchanging information about the state
of the art, current research and deve-
lopment.
The fourth annual North American
Program on Computer Assisted
Orthopaedic Surgery (CAOS/USA
2000), will be held from June 15 to 17,
Contact
information
If you would like additional
information or if you would
like to visit our MRCAS pro-
gram, please call:
(412) 623-2673
or explore our web sites at
www.cor.ssh.edu
www.mrcas.ri.cmu.edu
or contact:
Dr Anthony M. DiGioia
tony@cor.ssh.edu
Research Office:
Centers for Medical Robotics &
Computer Assisted Surgery
UPMC Shadyside
5200 Centre Avenue, Suite 309,
Pittsburgh, PA 15232
Phone (412) 623-2673
Fax (412) 623-1108
tony@cor.ssh.edu
www.cor.ssh.edu
www.mrcas.ri.cmu.edu
MRCAS Team Members at
Carnegie Mellon University
and UPMC Shadyside:
Laura Cassenti
Karen Cwynar
Anthony M. DiGioia III, MD
Kaigham Gabriel, PhD
Branislav Jaramaz, PhD
Takeo Kanade, PhD
Richard LaBarca, MS
Timothy J. Levison, MS
Yanxi Liu, PhD
James Moody, MS
Patrick Muir, PhD
Constantinos Nikou, MS
Frederic Picard, MD
Cameron Riviere, PhD

focus on
2000 in Pittsburgh. Dr DiGioia will
chair CAOS/USA 2000. The Program
will emphasize state of the art techno-
logies and perspectives on the rapidly
evolving field of computer assisted
orthopaedic surgery. The conference is
designed for practicing orthopaedic
surgeons and will educate participants
on computer assisted and image gui-
ded surgical techniques and robotic
assistive devices. CAOS/USA will also
present the most current views on the
impact of computer assisted surgical
techniques on the clinical and surgical
routine in several orthopaedic subspe-
cialties and promote a new partnership
between surgeons, technologists, and
industry as a critical foundation for the
successful integration of these tech-
niques into routine clinical practice.
Dr DiGioia will also co-chair the third
international Medical Imaging,
Computing, and Computer Assisted
Intervention (MICCAI) conference on
medical robotics, imaging and compu-
ter assisted in Pittsburgh, October 11-
14, 2000. Topics to be addressed at the
event include clinical applications of
computer technologies and systems,
computer-assisted intervention sys-
tems and robotics, as well as medical
imaging and computing for multiple
surgical and medical subspecialties.
For information on the CAOS/USA 2000 event
visit www.caosusa.org
and for MICCAI 2000 visit
www.miccai.org
For additional information on CAOS/USA
2000 and MICCAI 2000, you can also contact:
Preferred Meeting Management, Inc.
2320 6th Avenue, San Diego
CA 92101-1643, USA
Phone (619) 232-9499,
Fax (619) 232-0799
Establishment of the
International Society for
Computer Assisted Orthopaedic
Surgery (CAOS-International)
The area of computer assisted ortho-
paedic surgery has become so active
worldwide that it was time for a for-
mation of a society that will enable
exchange of ideas and contacts and
serve to facilitate future collabora-
tions. Dr Anthony DiGioia and the
MRCAS program in conjunction with
Dr Lutz Nolte from the University of
Bern-M.E. M¸ller Institute were ins-
trumental in establishing the first ever
International Society for Computer
Assisted Orthopaedic Surgery (CAOS-
International). The Society will have
headquarters in Bern, Switzerland and
the North American office will be hou-
sed at UPMC Shadyside Hospital. Dr
DiGioia is a founding member and was
elected as the Inaugural First Vice-
President of the Society. Dr Branislav
Jaramaz, also from the MRCAS pro-
gram, will serve as Treasurer. The First
CAOS-International Conference will
be held in Davos in 2001. The 2002
meeting will be in North America and
hosted by Dr DiGioia.
The purpose of this non-profit organi-
zation is to bring together those indi-
viduals throughout the world, who, by
their contributions and activities in the
areas of research, clinical study, and cli-
nical use, have or are interested in
computer assisted orthopaedic sur-
gery. Its further purpose will be to
serve as a forum for the exchange of
information of both an investigative
and clinical nature which relates to
preoperative planning, intraoperative
execution, postoperative follow up and
clinical outcomes by means of compu-
ter assistance. The Society also aims to
promote a new partnership between
orthopaedic surgeons and technolo-
gists as a necessary basis for the suc-
cessful integration of computer assisted
surgical tools and techniques into the
daily clinical routine.
For information on the CAOS-
International/USA 2000 event visit
caos@caos-international.org
American Academy of
Orthopaedic Surgery Establishes
a Special Interest Group on
Robotics and Computer Assisted
Orthopaedic Surgery (RCAOS)
The American Academy of
Orthopaedic Surgeons (AAOS) has
recognized the potential impact of
computer assisted surgical tools and
related innovations on surgical prac-
tice. An AAOS sponsored Robotics and
Computer Assisted Orthopaedic
Surgery/Special Interest Group
(RCAOS/SIG) has been established by
Dr DiGioia in 2000. RCAOS will sup-
port the exchange of information in
state-of-the-art techniques and pers-
pectives in this rapidly evolving field
including the areas of robotics, surgical
simulators and planners, intra-opera-
tive navigational systems and hybrid
reality. The first RCAOS/SIG Meeting
was held during the recent 2000 AAOS
Conference and attended by an enthu-
siastic group.
RCAOS/SIG is open to all orthopaedic
surgeons and will assist participants to
more effectively understand and relate
robotics, image guided and computer
assisted surgical systems to clinical
orthopaedic practice; demonstrate cur-
rent clinical applications using RCAOS
technologies; obtain an international
perspective on the current state-of-the-
art as well as future developments
planned for computer assisted surgery
systems; and identify the clinical and
technical issues and trends in robotics
and computer assisted surgery. ■
Dr Anthony DiGioia

An 89-year-old woman presented with
intractable low back pain and weakness
in the L5 innervated musculature. She
also complained of neurogenic claudi-
cation after ambulating for 50 meters.
Lateral radiographs revealed multile-
vel disk degeneration at L2-L3, L3-L4,
and L5-S1. There was a degenerative
spondylolisthesis at L4-L5 but normal
alignment on the AP view.
Lateral myelography revealed a com-
plete block at L5 and multilevel central
and foraminal stenosis was confirmed
by CT scan. In light of the patient’s
age, we attempted to perform as mini-
mal of a surgical procedure as possible.
The procedure consisted of a decom-
pressive laminectomy from L2-L5 aug-
mented by fusion of the unstable seg-
ment (L4-L5) with Twinflex
instrumentation. ■
Christian Mazel, MD
Head of the Orthopaedic and
Spinal Surgery department
Institut Mutualiste Montsouris
42, boulevard Jourdan
75014 Paris FRANCE
Phone +33 1 56 61 62 63
Fax +33 1 56 61 63 37
christian.mazel@imm.fr
Degenerative spondylolisthesis
associated with lumbar stenosis
By Dr Christian MAZEL (IMM Choisy - PARIS) ■
clinical
cases
AP/lateral preoperative x-ray
AP/ lateral postoperative x-ray
AP/lateral preoperative myelography
CT scan

clinical
cases
A 56-year-old woman presented with a
six-month history of left-sided sciatica,
neurogenic claudication, and a foot
drop. She also noted shooting pains
with any sudden change of position,
which were interpreted as evidence of
dynamic instability.
Radiographic examination revealed
severe disk degeneration at L5-S1,
early degeneration at L3-L4 with slight
anterolisthesis, and severe stenosis of
the left L5-S1 foramen. EMG confir-
med compression of the left L5 nerve
root and dynamic radiographs showed
instability at L3- L4, and L4-L5.
On October 18, 1995, wide left L5-S1
laminotomies were performed for
decompression. Fusion from L3 to the
sacrum was performed using Twinflex
instrumentation.
Three months postoperatively the
patient was able to walk for an hour
without pain, and at 12 months’ follo-
wup, the fusion had consolidated,
although the lumbar lordosis had not
been completely restored.
The patient was quite satisfied with her
outcome despite some mild persistent
bilateral sacroiliac discomfort. ■
Philippe Bedat, MD
Cabinet médical
36, avenue Théodore Weber
1208 Genève SWITZERLAND
Phone +41 22 736 0902
Fax +41 22 736 0494
pbedat@bluewin.ch
Lumbar canal stenosis and instability
By Dr Philippe BEDAT (Genève SWITZERLAND) ■
Post-operative X-rays
Preoperative functional saccoradiculography

technologies
New X-ray detector
Millions of x-rays are
performed each year. For
instance, the treatment of a
child with scoliosis requires as
many as four x-rays per year.
However, radiography is not a
harmless procedure, as it must
be remembered that
considerable doses of
irradiation are absorbed by
the human body.
CONSEQUENTLY, since the
beginning of the 1980s, some
efforts have been devoted to designing
systems based on digital amplifiers and
laser images in which conventional
films are replaced by photosensitive
cassettes. These devices reduce the
irradiation dose by twenty per cent.
The government agencies have also
stressed the importance of medical
radiation exposure, with recent EUR-
ATOM recommendations from ICPR
and the european community. The
work conducted by Georges Charpak
(Nobel Prize for Physics in 1992) on
the proportional multiwire chamber
has led in the early nineties to a low
dose prototype which was clinically
tested at Hopital St Vincent de Paul,
Paris, on children and teenagers. The
study showed unambiguously the capa-
city of the prototype to provide good
quality radiographic images at a patient
dose reduced by up to 20 times.
The original feature of this apparatus is
its detector, a proportional multiwire
chamber, designed and developed by
Charpak for nuclear physics experi-
ments at CERN, for which he was
awarded the Nobel Prize for Physics in
1992. The device is based on the detec-
tion of X rays in a gaz, here xenon and
CO2, conversion into electrons and
subsequent amplification. Its major dif-
ference with other X ray detectors is its
sensitivity to individual X photons,
making it a great detector for low dose
exposures. The detector is linear, and is
scanned together with the X ray tube
along the region of interest. To reduce
all radiations due to scatter, two linear
collimators ensure a flat fan beam that
is perfectly adjusted to the linear
detector dimensions. That method
allows a total suppression of scatter, as
only the slice of the body that is expo-
sed at a given time receives radiation.
In the prototype tested in 96, each
pixel of the detector was made of a 5
cm long wire connected to an amplifier,
discriminator and counter. The wire
pitch was 1,2 mm, resulting in a reso-
lution of about 0,6mm after signal pro-
cessing. The digital data are then accu-
mulated and displayed on a personal
computer for clinical analysis. All fea-
tures of a digital system, such as auto-
matic density measurements, distance
measurements and digital zoom are
available with such a system. The
detector is a true digital one, where
there is no need for digitization or laser
scanning. Data from the detector can
also be easily integrated into conven-
tional digital radiology systems (repro-
duction, transmission, filing, etc.).
Biospace, the company created by
Charpak to derive biomedical imaging
systems from innovative detector tech-
nologies, is currently developing a
new system for low dose radiology.
Using a new patented technology
based on micropattern detectors, the
new system will have the low dose fea-
tures of the first protoype together with
a higher resolution and scanning
speed. The product in development is
a two heads instrument, in which two
simultaneous, perpendicular (front and
side) X ray radiographs are taken. For
spine examinations, the pratician will
have the possibility to analyze these
two planar views as well as a tridimen-
sional reconstruction of the spine, a
feature currently developed by the
Laboratoire de Biomécanique of
ENSAM, Paris in collaboration with
Biospace. First results with the new
detector technology showed unprece-
dented high morphometric precision in
the 3D reconstruction of vertebrae.
Besides being a low dose radiology
equipment, the new development could
be a good alternative to highly irradia-
ting CT scan exams for spine exams. ■
Nobel Prize Winner,
Pr Georges Charpak
contribution to medicine
A new X-ray detector from nuclear physics

communication
Thank you for your contribution !
We will see you next year…

ARGENTINA
Dr Yvan R. AYERZA
Dr Juan Pablo BERNASCONI
Dr Pedro Ariel COLL
Dr Alysudro Cesar D’INNOCENZO
Dr Boan OSVALDO FERNANDEZ
Dr Frederic J. GELOSI
Dr Felipe Zubiaur LANARI
Dr Carlos Aroldo LEGARRETA
Dr Jose Luis MONAYER
Dr Luis A. PATALANO
Dr Pablo PLATER
Dr Victor G. RAMANZIN
Dr Gustavo RAMIREZ
Dr Roberto Carlos RODRIGUEZ
Dr Gabriel ROSITTO
Dr Victor ROSITTO
Dr Tomas RÜDT
Dr Eduardo SEMBER
Dr Pablo Mario SIRNA
Dr Carlos A. SOLA
Dr Edouardo Angel SOSA
Dr Gustavo Roberto ZISUELA
BELGIUM
Dr Henri COSTA*
Dr Guido DELEFORTRIE
Dr Damien DESMETTE*
Dr Sabri EL BANNA*
Dr Jean-Paul FORTHOMME*
Dr Jean LEGAYE
Dr Frédéric MATHEI
Dr Yves RYSSELINCK
BRAZIL
Dr André Rafael HÜBNER
CANADA
Pr Jacques DE GUISE
CHINA
Pr John LEONG
EGYPT
Dr Talaat EL-HADIDI
FRANCE
Dr Joseph ABIKHALIL
Dr Pierre ANTONIETTI
Pr Claude ARGENSON
Dr Xavier ARTIERES
Dr Mohamed Kamel BENCHENOUF
Dr Robert BOUVET
Dr Ilhem CHERRAK
Pr Denis CORDONNIER*
Pr Alain DEBURGE
Dr Jean-François DESROUSSEAUX*
Pr Jean-Claude DOSCH
Dr Brice EDOUARD
Dr Gilles GAGNA
Dr Franck GOSSET*
Dr Alain GRAFTIAUX*
Pr Pierre GUIGUI
Dr Michel GUILLAUMAT
Dr Pierre HEISSLER
Dr Yves JABY
Dr Henri JUDET*
Pr Pierre KEHR*
Pr François LAVASTE*
Dr LEONARD
Pr René LOUIS
Dr Jean-Luc MARMORAT
FRANCE
Dr Christian MAZEL*
Pr Serge NAZARIAN
Pr Michel ONIMUS
Dr François PODDEVIN
Dr Olivier RICART
Pr Gérard SAILLANT
Pr Jacques SENEGAS
Pr Wafa SKALLI*
Dr Joël SORBIER*
Pr Jean-Paul STEIB*
Dr Alexandre TEMPLIER*
Dr Richard TERRACHER*
Pr Jean-Marc VITAL*
GERMANY
Dr Jens DÄNENNBERG
Dr Ferdinand KRAPPEL
Pr Andreas WEIDNER
GREECE
Dr Panagiotis KOROVESSIS
Pr Demetre KORRES*
HUNGARY
Dr Tamas ILLES*
ISRAEL
Dr CASPI
ITALY
Dr Flavio BADO
Dr Paolo BONACINA
Dr Luigi CATANI
Dr Vincenzo DENARO
Mr. Charles-Marc LAAGER*
Dr Tonino MASCITTI
Pr Giovanni PERETTI*
Dr Carlo PIERGENTILI
Dr Dario RODIO
Dr Michele Attilio ROSA
JAPAN
Dr Kiyoshi KUMANO
Dr Junichi KUNOGI
LUXEMBOURG
Dr Adrien WIJNE*
THE NETHERLANDS
Dr Willem F. LUITJES
PORTUGAL
Dr Joao CANNAS
Dr Luis DE ALMEIDA
ROMANIA
Pr Mihai JIANU
SENEGAL
Dr Seydina Issa Laye SEYE
SOUTH AFRICA
Dr Johan WASSERMAN
SPAIN
Dr Fernando ALVAREZ RUIZ
Dr Diego BRAGADO NAVARRO
Dr Sergio CABRERA MEDINA
Dr Alfonso CAMPUZANO
Dr J.M. CASAMITJANA FERRANDIZ
Dr J. Ignacio CIMARA DIAZ
Dr Jose Maria CORBOCHO GIRONES
Dr Alvaro DE BLAS ORLANDO
Dr Jose Antonio DE MIGUEL VIELBA
Dr Angel Jorge ECHEVERRI BARREIRO*
Dr Manuel FERNANDEZ GONZALEZ
Dr Fernando FERNANDEZ MANCILLA
Dr Luis Antonio GARCIA
Dr Antonio GIMENEZ
Dr Francisco GONZALEZ
Dr Ernesto GONZALEZ RODRIGUEZ
Dr Angel GONZALEZ SAMANIEGO
Dr Cesar HERNANDEZ GARCIA
Dr Carlos HERNANDO ARRIBAS
Dr Eduardo HEVIA
Dr Juan HUERTA
Dr Alberto ISLA GUERRERO
Dr Manuel LAGUIA
Dr Rafael LLOMBART AIS
Dr Juan Antonio LOZANO-REQUENA
Dr Carlos LUNA
Dr Antonio MARTIN BENLLOCH*
Dr Jose Ignacio MARUENDA
Dr Cesar PEREZ JIMENEZ
Dr Enrique RODA FRADE
Dr Manuel SANCHEZ VERA
Dr Hugo SANTOS BENITEZ
Dr Jose Luis SOPESEN MARIN
Dr Agustin VELLOSO LANUZA
Dr Javier VICENTE THOMAS
Dr Julio Alfonso VILAR PEREZ
SWITZERLAND
Dr Philippe BEDAT*
Pr Michel DUTOIT*
Dr Bernard JEANNERET
Dr Denis KAECH
Pr Thierry SELZ
SYRIA
Dr Taha ALOMAR
TUNISIA
Dr Mohamed Habib KAMOUN
Dr M. Fethi LADEB
Dr Mondher M'BAREK
Dr Mongi MILADI*
UK
Pr John P. O’BRIEN
Dr Constantin SCHIZAS
USA
Dr Michael ALBERT
Dr Patrick BERTRANOU*
Dr Fabien BITAN*
Pr Jean-Pierre FARCY*
Dr Eric JONES*
Dr David LANGE
Dr Vincent J. LEONE
Pr Joseph MARGULIES
Pr S.M. REZAIAN
Dr William RODGERS*
* full members being entitled to sponsor
AArrggooss’’ mmeemmbbeerrss lliisstt

OOrrggaanniizzaattiioonn cchhaarrtt
Christian
Mazel, MD
President
Jean-Paul
Forthomme, MD
Vice President
Alexandre
Templier, Msc, PhD
General manager
Pierre
Kehr, MD
Executive secretary
Alain
Graftiaux, MD
Treasurer
Communication committee
Training committee
Evaluation committee
Wafa
Skalli, PhD
President of the
committee
Jacques
De Guise, PhD
Michel
Dutoit, MD
Alain
Graftiaux, MD
Christian
Mazel, MD
Juan Antonio
Martin, MD
Henry
Judet, MD
Philippe
Bedat, MD
Pierre
Kehr, MD
Charles-Marc
Laager, PhD
Jean-Paul
Forthomme, MD
Henri
Costa, MD
Jean-Paul
Steib, MD
President of the
committee
Jean-Paul
Forthomme, MD
Franck
Gosset, MD
François
Lavaste, PhD
Richard
Terracher, MD
Jean-Marc
Vital, MD

Argos SpineNews 3

Empfohlen

Empfohlen

Weitere ähnliche Inhalte

Ähnlich wie Argos SpineNews 3

Ähnlich wie Argos SpineNews 3 (20)

Kürzlich hochgeladen

Kürzlich hochgeladen (20)

Argos SpineNews 3