Argos SpineNews 2

April 2001
News from the world of Spinal surgery and biomechanics
Focus on :
The spine engine :
an original theory on human locomotion
A new bipedicular implant
TIM-C : a laboratory
for the 3rd millenium
Medical applications of
shape memory alloys
Interview with Pr François
Lavaste - Part 2
NEW Technologies
in Spine Surgery
NEW Technologies
in Spine Surgery
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

Interview with Pr. François Lavaste :
what is biomechanics? 8
Readers Forum 14
PRAXIM
Interview with Mr Stéphane Lavallée 19
Fifth International Argos Symposium: A Spine Odyssey 24
Agenda 29
Web review 50
Interview with Professor S. Gracovetsky
The Spine Engine 33
OMNI-AXIAL Connector 40
Retrospective study on medical applications of
shape-memory alloys 42
Mrs. Jocelyne Troccaz
TIM-C Laboratory 15
Orthopaedic Surgery & Robotics at the
Technion’s Robotics Lab 47
Evaluation
Communication
Training
April 2001
News from the world of Spinal surgery and Biomechanics
SSuummmmaarryy

communication
What Biomechanics is ?
8 ARGOS SpineNews N° 3- April 2001
Who are the French
biomechanical engineers?
I think that the physiologist Simon
Bouisset is a major figure in the field of
movement analysis, while Comolet was
a famous biomechanical engineer in the
fluid biomechanics field. When he died,
this whole branch of biomechanics was
almost orphaned. Finally, Joannes
Dimnet represents an important figure
in the field of osteoarticular
biomechanics.
What have been the main phases
in the history of the LBM?
The LBM was created in 1972, but it
only really became a truly structured
laboratory after 1979. In 1985, the team
of scientists, formerly working in the
University of Paris XII, invited us to
participate in a DEA (postgraduate
training programme) that they had set
up in 1981. They suggested that we
include a biomechanics specialty in this
diploma. Our collaboration with the
CNRS (Centre National pour la
Recherche Scientifique) (French
National Scientific Research Center)
started in 1996 and was formalized in
1998. One year later, LBM was granted
COFRAC quality certification, which is
somewhat an exceptional situation for a
research laboratory. Very few
laboratories have obtained this type of
accreditation. I think only two CNRS
laboratories have been granted this
accreditation.
Is it true that Raymond Roy
Camille contacted you personally
to propose a research
collaboration?
Yes, when he came to propose this work,
he was head of the department of
orthopaedics of Poissy hospital in the
western suburbs of Paris. About one
year later, he was appointed head of the
department of orthopaedics at Pitié-
Salpêtrière hospital. Thus, we became
neighbours, geographically, but he had
developed his approach at a time when
we were not at all involved in this field.
Our subsequent collaboration greatly
facilitated all of our efforts. Our meeting
with Jean Dubousset and the Sofamor
company was a second important step in
the history of the LBM. This happened
in 1988, i.e. when Mrs Skalli joined our
team. In fact, our collaboration with
Sofamor was initiated by Guy Viart, who
was Chief Executive Officer at the time.
I think he asked us to present our
biomechanical activities dedicated to
the spine at Rang du Fliers, in the north
of France.
How did this collaboration with
manufacturers start?
I think this collaboration started as a the
result of interventions by clinicians, who
initially came to LBM for postgraduate
training in biomechanics. When they
subsequently questioned the various
companies supplying them with their
products and were unable to find a
solution to their problems, they
suggested that the manufacturers
contact ENSAM. This circuit
constituted a major step in the
development of the LBM. When
clinicians and manufacturers came to
ENSAM to validate their mechanical
ideas, we advanced from a highly
intuitive field to a much more objective
field.
What was Guy Viart contribution
to this development?
He is obviously one of the leading
figures who developed this link between
the LBM and industry. In reality, this
link is actually an association between
surgeons, manufacturers and research
laboratories.
Would it be conceivable for other
specialties to be involved in this
association?
This association is already spreading to
other areas. We need the skills of a
materials specialist to solve problems of
wear, and a biocompatibility specialist,
i.e. a chemist. We will also need a
mechatronician (combination of
Interview with Pr. Franç
what is biomechanics?
This third issue of Argos SpineNews includes the final part of the inter-
view with François Lavaste. After defining the field of biomechanics and
after briefly describing the history of the prestigious laboratory that he
manages, François Lavaste hereafter explains why the LBM is situated at
the crossroads of science, medicine and industry.
Stereoradiography - a 3D medical imaging
technique (Collaboration study: LBM
ENSAM Paris - ETS, Ecole Polytechnique
Montréal)

mechanics, electronics and data
processing) as we intend to
progressively install systems inside the
human body that could be controlled
from outside the body (see article on
nanotechnologies ARGOS SPINE
NEWS No. 2). Consequently, we are no
longer dealing with mechanics alone,
but mechanics plus electronics, plus
data processing and materials.
Biomechanical engineers are obliged to
complete their research teams with the
contributions of other specialists.
Would you say that this process
constitutes an additional step in
the evolution of biomechanics?
Yes, these changes are clearly illustrated
by the collaborations in the field of
imaging. We obviously need to give a
shape, a geometry to our mechanical
objects and our models. Imaging was
initially standardized, but now there is a
growing trend towards personalization.
In the longer term, imaging will also
provide us with information about
mechanical characteristics. This is why
this type of collaboration is so important.
The LBM stands at the
crossroads between science and
industry.
I would even say that it is at the
crossroads between science, industry
and clinical practice.
While visiting your website, we
noticed that you place particular
emphasis on the concept of a
multidisciplinary approach. So
how is your research organized
within the LBM?
In relation to the concept of a
multidisciplinary approach, I would say
that two basic disciplines are associated:
orthopaedics and mechanics. Each of
these disciplines then uses certain
complementary skills. For example,
imaging in the case of orthopaedics.
Sometimes our work is conducted in
collaboration with surgeons specialized
in vascular systems. On the mechanical
side, we need computer programmers
and automaticians. Certain skills beyond
the field of mechanics must be added.
What are the current relations
between the LBM and the world
of surgery?
I think we have two sorts of relations
with the sphere of surgery. Firstly, we
have relations in the field of training, as
we have trained almost 150 surgeons
since 1985, who now form a network
throughout France, and thus we have a
contact in almost every teaching hospital
in France. For example, in the East of
France, we collaborate with Professor
J.P. Steib, and, in the South-West, with
Professor J.M. Vital. I especially
remember the first batch of graduates in
1985.
Do many surgeons still want to
pursue this training?
Yes, there is a strong demand on the part
of clinicians, but we can only accept ten
surgeons per year. This is certainly not a
great number each year, but it means
that only the most motivated surgeons
are able to join our team. This also
explains the close bonds that have been
established with various hospitals. Five
or six members of the ARGOS
association are surgeons who have
completed this biomechanics training.
You are also a member of ARGOS;
in what way can the Association
April 2001 - N° 3 ARGOS SpineNews 9
communication
ois Lavaste : PART
Numerical model of the spine - Collaboration LBM - Sofamor Danek

communication
contribute to the exchanges
between biomechanical
engineers and surgeons, and
possibly manufacturers?
It is always the same objective:to
promote closer bonds between
specialists from various disciplines. It is
a forum in which each member can
benefit from the other's experience
without any further reason. This is
important, as, in the early days of LBM,
people predicted that our project would
fail since we would never be able to
collaborate with the medical profession,
a closed and self-confident world. We
were even warned that we would
become servants to these “superior”
masters. But the reality was very
different, as the relationships that we
established through formation of the
DEA training programme allowed us to
understand and respect each other.
Has the LBM established joint
projects with industry and
especially with the automobile
industry?
Our collaborations with the automobile
industry represent a knowledge transfer
from orthopaedics to the automobile
industry. We made every effort to
demonstrate the advantages of
modelling the human body as we had
previously done for orthopaedics. It took
6 months of discussion to convince
them, because they were not at all ready
to accept this type of approach. At the
time, they were essentially working with
mechanical dummies, but we eventually
convinced them to undertake an
operation supported by the French
Ministry of Research. This was in 1990,
and the process then started to develop
fairly rapidly. Car manufacturers were
already interested in biomechanics
using dummies, and tests with cadavers
placed in vehicles. They simulated the
shock and then examined the lesions
caused to the bodies. We provided a
representation of the human body with
our digital models and simulations.
Has this type of collaboration
between the LBM and car
manufacturers also been
developed in other countries?
I think that France was one of the
leading cou ntries in this field. We were
one of the first countries to possess a
complete model of the human
body designed to simulate the
behaviour of the body in
response to shocks. Things
then moved very rapidly; five
years later, in 1990, we already
had the first elements of the
virtual human body. In 1998,
our modelling was operational
and, at the same time, our
approach was adopted by
several other countries. Today,
in 2000, most car
manufacturers are interested
in live models, but this wasn't the case at
the outset.
Why did you decide to develop
this collaboration with the
automobile industry when you
could have confined your
interests to the surgical field?
The director of biomechanical research
of two leading French car manufacturers
(PSA, Renault) was a doctor. He had an
idea very similar to our own concerning
the value of biomechanics both in the
field of orthopaedics and in the field of
protection of the body in motor vehicles.
This convergence of our two viewpoints
and this easy relationship convinced us
of the advantages of working together.
We initiated a period of cooperation
through a whole series of doctorate
theses.
Is it still just as difficult to
collaborate with the automobile
industry?
No, it has now become routine. We work
with car manufacturers in the context of
European contracts. It has now become
standard practice. Our work is
conducted in collaboration with the
INRETS (Institut National de
Recherche sur les Transports et leur
Sécurité - National Transport Security
Research Institute). Our research and
that of the automobile industry are
closely related.
Optoelectronic motion capture of the lower limb on stairs (left) and analysis of the gait (right)
Mechanical and geometrical modelling of
the lower cervical spine
Experimental study of the behaviour
of an instrumented lumbar segment
with the VICON optoelectronic system
▲
▲

Do car manufacturers now
systematically call on
biomechanical engineers when
studying a new project?
Biomechanics has gradually become an
integral part of the design of a motor
vehicle, but this is obviously not the only
element to be taken into account. This is
an interesting development, as the
engineers and scientists that we have
trained now work in the research
departments of leading car manufacturers,
where they use models which were
designed at the LBM in the frame of our
research. We have progressed from a fairly
abstract idea, considered to be somewhat
bizarre, to a very concrete application: a
technological transfer in the field of car
design.
Isn't this a form of «reward»?
I recently received a call from one of my
former doctorate students. I asked him
what he was doing now, and he replied
that he was in charge of setting up all of
the infrastructure to allow application of
the models designed at LBM for a leading
French car manufacturer. This means that
we were not unrealistic when we
proposed this research programme ten
years ago!
Do other areas of industry make
use of the services provided by
biomechanics?
There is another field of application with
which I am much less familiar. It concerns
military applications, both in the field of
aeronautics and the army. They have very
different objectives, as they want to
determine the behaviours of the human
body either to protect it or to destroy it.
We have not had any experience in this
field. It is a branch of biomechanics which
publishes fewer papers and which is less
present in the scientific community, but it
is nevertheless a reality!
communication
PURPOSE :
The purpose of this training is to provide the main principles of mechanics
in order to apply them in the study of the biomechanical behaviour of
bony structures, ligaments, muscles (spine, coxo-femoral joint, knee…)
- in order to better analyze the mechanical functions of the skeleton,
either healthy or pathological
- in order to optimize the design and manufacturing of mechanical devices
allowing to restore or assist the damaged functions (prostheses,
ostheosynthesis materials …)
The training addresses to:
- Orthopædics surgeons (fellows, MD, hospital staff, department heads);
- Medical doctors in functional rehabilitation;
- Biomedical engineers and technicians
PROGRAM :
■ Joint Kinematics and dynamics
• theoretical principles
• experimental tools:
- Fastrak electromagnetic 3D measuring device
- Zebris ultrasound 3D measuring device
- Vicon opto-electronic 3D measuring device
■ Eperimental analysis of the biomechanical behaviour of the spine, the knee …
■ The use of the Finite Elements Modelling technique in Biomechanics
■ Geometrical and mechanical modelling of the spine and of the human skeleton
joints
■ Modelling and experimental analysis of the behavior of spinal implants and
joint prostheses
■ Workshops on geometrical and mechanical modelling using the Finite
Elements Method
LANGUAGE: French only
REGISTRATION FEE: 7 000 FF.
LOCATION : ENSAM de Paris - 151 bd de l'Hôpital – 75013 PARIS
CONTACT: Michel POMPIDOU – Training Programmes Manager
PHONE: +33(0)1.44.24.64.90
BOOKING: FAX: +33 (0)1.44.24.64.74
REGISTRATION LIMIT: 10 people.
Initiation to BIOMECHANICS
for Implant Design and Manufacturing
(Experimental analysis and modelling)
4 days training : 7, 8, 11, 12 juin 2001

Do you have any contacts with
this branch of biomechanics?
I know that it exists ... I have certain
ideas about their research, but I do not
have any direct contact with them. I
think that they have their own
specialized teams, and that they conduct
a very particular type of research. Is it
possible to develop a projectile that can
travel throughout the body and destroy
it? Is it possible to determine how the
projectile reacts when it meets a
resistant material such as bone? Can this
same projectile be deviated to that it has
a larger trajectory, etc. ? These are the
types of problems that military scientists
try to solve. It nevertheless remains a
biomechanical approach. They have also
designed models to investigate these
questions. There have been attempts to
collaborate in the context of the "Fenit"
programme, which was set up by the
French Ministry of Transport and
Industry to improve problems of
security, ergonomy and comfort related
to road transport. We held a joint
meeting with military scientists at which
they have presented their research
programmes. We have also evaluated
the mechanical characteristics of the
army's fixation device (a bone fracture
stabilization system) but, in this
particular case, the application
concerned orthopaedics.
Back on the subject of
orthopaedics, what are the main
contributions of the LBM to
spinal surgery?
I don't know whether we can claim to
have contributed to the progress of
spinal surgery, but I think we have
provided certain objective elements to
the assessment of biologic phenomena.
We have developed simulations using
digital models tested on anatomic
specimens in order to obtain
quantitative information. Once again, I
don't think we can claim to have made
an extraordinary contribution, but I
think that we have facilitated a better
understanding of biomechanical
phenomena within the spine: its
behaviour, function, reaction to implants
(and everything concerning bone
remodelling around implants),
stabilization of the human body, and the
correction of scoliosis. We have
provided greater objectivity to the
surgeon's subjective assessment. We are
now working with clinicians in the
surgical planning phases. They prepare
the procedure on the basis of data of the
clinical examination and
radiographs, i.e. qualitative
elements. The surgeon examines
his patient and then uses his
surgical experience. As an
example, we can provide him,
with a quantitative analysis of the
rigidity of scoliotic curvatures by
simulating the behaviour of the
spine, which enables the surgeon
to integrate additional information
into planning of the surgical
procedure. When we reconstruct
the spine in three dimensions and
obtain spatial geometric data, we
try to understand how optimally to
restore the vertebral column and
reduce scoliotic curvatures.
What are LBM's main projects?
Essentially,we have two main types of
projects. At the level of basic research,
we are developing increasingly precise
models, towards a virtual human body.
Another actively growing field is our
desire to assist in preoperative
assessment, intraoperative practice, and
postoperative evaluation. We are not
trying to hold the surgeon's hand, but
rather to provide him with information
during the surgical procedure.
Providing the surgeon with real-time
information about the state of the
curvature on which he is operating and
on the degree of correction of this
curvature constitutes a good example of
objective assessment. Globally, a visual
display will allow the surgeon to see the
state of progress of the spine during
treatment and, in parallel, it will also
provide him with quantitative
information about the curvature to be
increased. This information will allow
the surgeon to optimize the procedure
without replacing the surgeon by a
robot. Qualitative and quantitative data
are combined to ensure an increasingly
effective procedure. ■
Interview by C.S. Parent
communication
Study of the mechanical
behaviour of a femur in
monopodal position
3D FEA modelling of the human
knee (LBM-ENSAM, Compared
Anatomy Laboratory - Natural
History Museum, Paris, URA
CNRS 1137)
3D FEA modelling of a knee
prosthesis (LBM-ENSAM,
CEDIOR)

communication
Readers Forum
Readers Forum
Readers Forum
To the editorial staff of ARGOS Spine News,
Please allow me to congratulate you on this
beautiful new publication, ARGOS Spine News. I
wish to comment on your interview with Pr
François Lavaste. You posed the question: What
is biomechanics? I would offer the observation
that Orthopaedic Surgery is a combination medical
sciences surgical art and mechanical principle which
when is applied in human, and thus is Biomechanics.
In light of this, we should not forget the work of
Nicolas Andry, a leader of eighteeneth century
medicine who wrote his thesis in Orthopaedics in 1744.(editor’s note:
how could he write his thesis in 1744, if he died in 1742?) He had
observed gardeners supporting falling trees and applied this
mechanical principle to the design of a brace for correcting kyphosis
in children. This principle, as demonstrated in my letterhead, became
the accepted symbol of orthopaedics.
Nicolas Andry studied medicine at Rome and Paris and received the
degree in medicine in 1697 at age 39. Four years later he was
appointed as professor in the college de France and a member of the
editorial board of the Journal des (editor’s note: what is this?) In
1724, he assumed the post of Dean of Faculty of Medicine.
Andry actually coined the word “Orthopedie”. To quote: “As to the
title, I have formed it of two Greek Words, viz, Orthos, which signifies
straight (sic) or free from deformity, and pais, a child. Out of those
two words I have created L’Orthopedie to describe my different
method of preventing and correcting deformities in children.” His
book contains fundamental information on curvature of spine,
clubfeet, and congenital dislocation of the hip. Andry died in 1742,
one year after the publication of L’Orthopedie.
A brief glance at L’Orthopedie will remind us of the debt we as
orthopaedic surgeons owe this great man. It is now time that we
recognize him as the founder of biomechanics, too.

ASN: What led you to the field of
computer-assisted surgery?
JT: I trained in computer science and
joined the TIMC laboratory after a
doctorate thesis in Grenoble in
computer science or, more precisely,
robotics in a laboratory with no activity
in the biomedical field. In 1990, I
decided to spend a year at TIMC to
broaden my range of skills in robotics. I
was immediately attracted by the
clinical application of this field and, as
such, I did not leave the laboratory at
the end of the year. I was a research
scientist from 1990 to 1996, when I was
appointed director of the CAMSP
group.
ASN: When and why was the
TIMC laboratory founded?
The TIMC laboratory was founded in
the early1980s within Joseph Fourier
University, then called Université
scientifique, technologique et médicale
(scientific, technological and medical
university) (Faculties of medicine and
science). The Dean, Professor Sarrazin,
wanted to create a research department
composed of scientists, clinicians and
biologists and to pursue
medicalprogress by novel scientific
approaches. In 1982, Jacques
Demongeot, medical doctor and
mathematician, created this department,
which was initially called "the
Department of Biostatistics". It was
renamed TIMC (Techniques de
l'Imagerie, de la Modélisation, et de la
Cognition - Imaging, Modelling, and
Cognition Techniques) but maintains
the same multidisciplinary approach of
close research collaboration, without
placing the engineer at the service of the
clinicians, or vice versa.
ASN: What are the main activities
of the TIMC?
The common denominator of all of our
research activities is the application of
mathematics and computer science to
medicine and biology. The TIMC is now
composed of 8 teams, ranging from basic
science to more applied research
(modelling, image processing, artificial
intelligence, microtransducers, genomic
databases, physiology of breathing,
CAMSP)and we have a very broad range
of research topics.
ASN: Who are your main clinical
partners?
Proximity facilitates our collaboration
with about twenty departments of
Grenoble teaching hospital, Professor
Philippe MERLOZ, (in spinal surgery),
Professor SARAGAGLIA (South
Hospital, Department of Orthopaedics),
and Professor Remi JULLIARD
(Clinique Mutualiste of Grenoble), are a
few of our closest colleagues. As you can
see, our clinical partnerships are
essentially local.
ASN: Do the engineers working
in the TIMC regularly visit
surgical departments?
It all depends on the type of research
work. Relatively basic research, such as
the design of a new robot, does not
require regular presence in the clinical
setting, at least in the early phases. In
contrast, other projects require part-
time or full-time presence of clinicians
in the laboratory in order to define the
needs and the environmental
constraints, and the presence of
engineers in the operating room for
validation and clinical trials.
ASN:How is the laboratory
composed?
The TIMC is composed of about 130
people: one-half are permanent, and
half are post-doctorate fellows or
doctorate students. The CAMSP team is
composed of about 30 people and
receives about fifteen students per year
(DEA, engineering students, DESS or
Master's students).
ASN: You introduced the concept
of CAMSP, which is broader than
that of computer-assisted
surgery. What are your activities
beyond the medical and surgical
procedure per se?
training
TIMC Laboratory
Mrs. Jocelyne Troccaz
The director of the CAMSP group (computer-assisted medical and surgical
procedures) in the TIMC laboratory (Techniques de l'Imagerie, de la
Modélisation, et de la Cognition), kindly allowed us to visit her laboratory,
near Grenoble teaching hospital. She gave us a guided tour of one of the
leading centers in computer-assisted surgery research.

training
TIMC Laboratory
We have worked or are currently
working in a number of non-surgical
areas, such as medical imaging (image
repositioning, data superimposition), in
collaboration with radiologists; we are
also currently working with radiologists
to develop 3D reconstructions from
intraoperative radiographs obtained by
digital transducers. Radiotherapy is
another research field (both for planning
and conduct of treatment). We are also
working in the field of respiratory
medicine in the form of computer-
assisted bronchoscopy . These are just a
few of our ongoing projects.
ASN: What are the main
international CAMSP research
laboratories?
It is hard to give a complete list. The
largest laboratory was formed relatively
recently at Johns Hopkins University
(Baltimore, USA) by Professor Russell
TAYLOR. Professor TAYLOR has a
deep robotics background (he designed
the Robodoc system) and after working
with IBM for many years, he coagulated
a research team around the theme of
CAMSP with the usual 3 axes (research,
training, and industrial partnerships),
with the financial support of the US
government.
In the United States, the research
centers in Boston, around MIT and
Harvard University, and in Pittsburgh at
UPMC Shadyside (See. ARGOS NEW
SPINE No. 2) also play a leading
predominant role. We often work with
the Helmöltz Institute team in Aachen,
Germany; Paolo DARIO's team is
particularly interested in
microtechnologies and robotics. In
Switzerland, Professor Lutz NOLTE at
the Müller Institute has specialized in
computer-assisted orthopaedics. A
number of teams have been set up in
England, for example the London team
directed by Prof. Brian DAVIES and
Prof. David HAWKES. In France,
centres such as INRIA, are more
specifically devoted to medical imaging
and various image processing
techniques. The TIMC is, in terms of
the number of projects developed and
the quality and close proximity of its
clinical partners, clearly one of the main
CAMSP laboratories in the world.
ASN: Who are the key people
who have nurtured these
relatively young disciplines over
the last ten years?
Without hesitation, Russell TAYLOR in
the United States, whose work on the
Robodoc system is largely responsible
for the media coverage of these
technologies.
In France, Philippe CINQUIN was
responsible for the development of
surgical navigation technologies in the
Grenoble region in the eighties, but it
must be remembered that this work
would not have seen the light of day
without the assistance of the clinicians
with whom we work. In spinal surgery,
for example, a real long-term
partnership has been developed with
Professor MERLOZ.
ASN: What proportion of your
research activity is devoted to
orthopaedic surgery?
I don't think it would be an exaggeration
to say that almost 50% of our clinical
activity concerns the field of
orthopaedics. We have many projects
concerning navigation in surgery of the
spine, pelvis, and knee (total
arthroplasty, ligamentoplasty), and
concerning medical imaging. Half of our
clinical partnerships and the various
ongoing European projects concern
orthopaedic surgery.
ASN: How are clinicians
integrated into your research
projects?
This integration is primarily "structural",
as the laboratory is partially composed of
medical doctors. Secondly, several
doctors and surgeons complete their
doctorate-of-science theses at the
TIMC, on a part-time basis,
simultaneously with their everyday
clinical practice. Once again, our
proximity to the Grenoble teaching
Peroperative 3D surface reconstruction of the lumbosacral spine using an ultrasound (echogaphy) system.
Percutaneaous screwing of the sacroiliac joint.
Semi-active serial robot. The robot is not
moving the pen, but the human hand is guided
by the robot on a pre-program track. Some
areas can be allowed, some others forbidden.

training
TIM-C Laboratory
hospital is a major advantage in this
context. These clinicians generally work
in teams with an engineer, who is also
preparing a doctorate-of-science thesis.
The contribution of doctors usually
concerns defining needs and
constraints, modalities of
experimentation, and clinical validation.
They are obviously a central component
of the industrial partnership.
ASN: In your opinion, what are
the major contributions of
CAMSP to spinal surgery at the
present time?
At present, our work centers on
navigation techniques for pedicle
fixation , but these contributions are
diversifying even as we speak.
ASN: For example?
Enhanced endoscopic surgery is
probably one of the main objectives of
CAMSP over the next decade. The
combination of navigation and
endoscopy technologies will soon allow
the development of new minimally
invasive techniques for spinal surgery.
With the progress in intraoperative
imaging, techniques will evolve and
new surgical approaches will be
possible. The integration of new
transducers into surgical
instrumentation could also
be a factor in technical
improvement.
ASN: Computer-
assisted pedicle
fixation currently
appears to hesitate
between tomographic
navigation (CT scan)
and fluoronavigation.
Where is this
technology going?
The choice of one or other
of these two modalities will
undoubtedly depend on the clinical
setting. The high radiation dosage
incumbent in CT would prevent it from
being used systematically, especially in
adolescent scoliosis. MRI may represent
an alternative in this setting. The
efficacy of fluoronavigation has yet to be
demonstrated. Fluoronavigation is very
promising since it does not require a
sophisticated preoperative examination
and uses less radiation, but, for the
moment, it can only provide medium
quality 2D images, which are markedly
inadequate in severe spinal deformities.
In any case, these techniques will
certainly be improved over the next few
years. We are also working on
techniques of intraoperative
repositioning of 3D CT reconstructions
of the spine by ultrasound, which will
open new perspectives in minimally
invasive surgery.
ASN: In your opinion, what is the
future of robotics in spinal
surgery?
Like all aspects of spinal surgery, this is
a difficult question! The presence of
sensitive anatomic structures, such as
nerve roots and the dura, makes the use
of robots particularly hazardous,
requiring extremely careful and detailed
risk assessment and, quite probably, the
design of new robotic approaches.
Unlike the classical robotic approaches
to orthopaedic surgery (Robodoc - ISS,
Caspar - Orthomaquet), our robotic
approach is not independent (the robot
automatically performs part of the
procedure), but dependent (the
procedure is performed entirely by the
surgeon, but limited in space by the
robot during the most delicate phases,
as if a "third hand" guided the surgeon's
hand to ensure that the procedure
follows the preoperative plan).
Miniaturization of robotic components,
especially operating devices and
transducers, will allow the clinical
diffusion of these robots in the near
future.
ASN: As the new millennium
begins, we are watching an
Internet explosion. What is the
role of the Internet in the
development of CAMSP?
The Internet will undoubtedly have a
dominant influence on training and
teleteaching. In my opinion, remote-
controlled surgery (or telesurgery) via
Internet at sites geographically distant
from each other, will be confined to the
field of isolated demonstration for many
years to come.
On the other hand, sharing of scientific
data and know-how between centers
specialized in a particular medical or
Image Guided Orthopaedic Surgery (Fluoronavigation)
Images guided pedicular screwing

surgical discipline is rapidly changing
the face of current teaching methods in
medicine and surgery, but we must
remember to pay particular attention to
the source and reliability of these data!
ASN: Do you have any
teleteaching project underway?
The VOEU project (Virtual Orthopaedic
European University) is an European
project following two other projects:
IGOS (Image Guided Orthopaedic
Surgery) and IGOS 2. These two
projects were designed to ensure the
development and clinical validation of
CAMSP systems in orthopaedic surgery.
The VOEU project is designed to
develop computer technologies in the
area of orthopaedic surgery teaching.
Several trials of access to training
through Internet have been organized,
especially in the field of pharmacology
at the Grenoble Faculty of Medicine.
These courses are interactive and not
exclusively comprised of text. For
example, various multimedia
questionnaires allow self-assessment of
candidates. In the context of the VOEU
project, models of orthopaedic surgery
training courses and simulation tools
(clinical models or surgery simulators)
are being developed, in the fields of
knee, hip, and pelvis surgery, and
shoulder arthroscopy.
ASN: What are your objectives
for the next ten years?
In the field of orthopaedic surgery,
particular emphasis will be placed on
the development of tools facilitating
minimally invasive surgical procedures.
Endoscopy, repositioning techniques
without palpation, such as ultrasound, or
3D interpretation of digital subtraction
x-rays (ongoing European MI3 Project)
are several examples. We can also expect
progress in image processing tools and
the development of new visualization
systems which will facilitate the clinical
use of surgical navigation systems.
Modelling of clinical data and anatomic
information, especially concerning soft
tissues, is a rapidly growing field of
research at TIMC (mainly in cardiac and
gastrointestinal surgery). Collaborations
between our discipline and
biomechanics will be one of the main
factors leading to innovation over the
years to come. The spine, for example,
has been the subject of many
biomechanical studies performed by
laboratories such as LBM-ENSAM,
directed by Professor François
LAVASTE and Wafa SKALLI (See
ARGOS SPINENEWS No. 2),
especially concerning geometric and
mechanical modelling of the healthy,
injured and reconstructed spine, but
also associated implants and surgical
techniques. These laboratories are also
increasingly developing their research
in the fields of medical imaging, which is
also one of our areas of interest.
Biomechanics and computer-assisted
surgery are complementary dsciplines,
which must collaborate more in the near
future to enhance the development of a
global therapeutic continuum, from
personalized modelling to the surgical
procedure and beyond to long-term
follow-up of the clinical results.
ASN: PRAXIM company, the
subject of another interview in
this issue, is one of your most
important partners. Can you tell
us more about this partnership?
PRAXIM previously ensured the link
between research and industrialization
(in the context of our partnerships with
major companies such as Medtronic,
Sofamor, Danek, or Aesculap). This
engineering activity has gradually been
replaced by an autonomous activity and
direct industrialization. The industrial
application of TIMC's research is
essentially ensured by PRAXIM, which
now produces its own navigation station
(Surgetics). ■
Interview by A. Templier
training
TIM-C Laboratory
Information Flow diagram in Computer Aided Surgery Systems development
3D surface matching by deformation of a 3D
statistical model

ASN: Can you explain to us what
led you to the field of computer-
assisted surgery?
SL: During my training as an engineer
at Sup'Télécom in Brest, I became
interested in the biomedical field and I
worked for companies in this field while
I was a student. I started a thesis in
Grenoble in the TIMC laboratory in
1986, with Philippe CINQUIN, who
was in the process of creating his
CAMSP team (computer-assisted
medical and surgical procedures). My
thesis subject concerned computer-
assisted percutaneous nucleolysis based
on CT images, and it seems to me that
this problem has still not been entirely
solved.
ASN: When and why was the
PRAXIM company created?
PRAXIM was founded in 1995 when a
group of scientists, including myself,
initially directed by Philippe CINQUIN
and later by Jocelyne TROCCAZ,
decided to develop a structure that
would facilitate the laboratory research
by association with leading medical
companies such as B-Braun (Aesculap),
Medtronic, Sofamor, Danek, or Stryker.
ASN: What are your fields of
interest apart from orthopaedic
surgery?
We are currently bringing products to
market in three fields. The first is
orthopaedic surgery in general, the
second is ENT (See Figure), intranasal
and cranial surgery, and the third is
dental and maxillofacial surgery, with a
specialization concerning computer-
assisted dental implantology.
ASN: What percentage of your
work is devoted to orthopaedic
surgery?
Orthopaedic surgery has a predominant
place in PRAXIM, in line with current
market trends. We believe thatwe have
an authentic explosion in computer-
assisted surgery in orthopaedics at the
present time, and we are participating in
this explosion, in both development and
marketing. The first PRAXIM
developments were applications in knee
(See figure) surgery and spinal surgery.
ASN: Can you briefly describe
the international computer-
assisted orthopaedic surgery
market?
There are approximately 1,500
computer-assisted surgery systems
throughout the world at the present
time, but only several hundred are
devoted to orthopaedics and
traumatology. This is a very rapidly
emerging market as a result of several
factors. The first one concerns the
growing demand expressed by patients
and identification of the real potential
applications of these technologies to
solve various problems in orthopaedics.
The locomotor apparatus is particularly
suitable to computer-assisted surgery,
which essentially concerns integration
of 3D geometry, modelling, and
registration. The second factor concerns
the orthopaedic implant manufacturers,
who consider these systems an
innovative and often clever way of
presenting and promoting their know-
how, and of providing their customers
with a real added value.
The third factor concerns the demand
by orthopaedic surgeons, who view
these systems as a natural step in the
evolution of technological and scientific
progress that makes their surgical
practice more reliable, increasingly
effective, and less invasive.
As a result of all of these factors, several
hundreds of these systems should be in
use in every industrialized country in
the near future.
communication
PRAXIM
Interview with
Mr Stéphane Lavallée
Chief Executive Officer of PRAXIM (Perception, Raisonnement, Action en
Médecine - Perception, Reasoning, Action in Medicine), is one of the worl-
d's leaders in computer-assisted surgery. He presents his approach to this
rapidly growing market and these new technologies.
Surgetics screen of the ENT navigation
software
Total Knee replacement planning
(Femoral implant).

communication
PRAXIM
ASN: You are marketing an
open navigation station
(SURGETICS) (See figures).
What are the main advantages of
this open device?
Two computer-assisted orthopaedic
surgery systems are available at the
present time: the so-called "closed"
systems, reserved for a specific implant
manufacturer, and the "open" systems,
such as our Surgetics device. Open
devices satisfy the surgeon's demand to
be able to work on multiple applications
with implants from various
manufacturers, who are often
competitors. The interest of an open
system is to allow the surgeon to
perform knee arthroplasty with
manufacturer X, spinal surgery with
manufacturer Y, anterior cruciate
ligament reconstruction with
manufacturer Z, and perform hip or
shoulder arthroplasty with another
manufacturer, etc.
ASN: What applications will be
available on SURGETICS within
the next two years?
We are going to start with the main
applications in orthopaedic surgery,
which obviously include the spine, with
a number of different variants.This also
includes knee arthroplasty, either total
or unicompartimental; knee
ligamentoplasty; lower limb
osteotomies, total hip arthroplasty and
traumatology, and especially femoral
pinning. Applications such as the
shoulder or ankle arthroplasty will be
developed subsequently.
ASN: You are a partner of
SURGIVIEW, specialized in the
development of computer-
assisted diagnosis and clinical
follow-up systems in orthopaedic
surgery. What is the purpose of
this partnership?
Navigation, which is at the core of the
operating room, is able to take various
types of data into account, and provide
very precise quantitative data derived
from a computerized surgical protocol
like those developed by Surgiview. If we
stopped at this point, we would lose an
important potential benefit of these
systems, which integrate these data into
the management of the operating room
and in the surgeon's everyday practice,
thus providing patients with an ever-
increasing quality of care. Our
partnership with SURGIVIEW is an
essential and strategic partnership.
ASN: Computer-assisted pedicle
fixation appears to hesitate
between classical navigation (CT
scan) and fluoronavigation. What
is your position?
The use of preoperative 3D imaging
remains essential in cases with severe
spinal deformities. In other more
common and less complicated cases,
fluoronavigation can be sufficient. In
addition to these two techniques, both
part of our portfolio, we propose an
intermediate solution, based on
intraoperative image acquisition using
fluoroscopy, with 3D geometric
reconstruction using an "atlas" type of
statistical model (See Figure). This
approach is designed to combine the
simplicity of fluoroscopy with the three
dimensional reconstruction available
with computerized.
the major innovations likely to be
developed over the next five
years in spinal surgery?
I think two main innovative aspects will
be combined. The first aspect, about
which everyone is talking, is minimally
invasive surgery, which is difficult to
implement with currently available
technologies. It will become easier and
even simple with the future
SURGETICS technology. The second
aspect is global visualization of the spine
during surgery, combined with
preoperative planning designed to
ensure an optimal procedure according
to the patient's preoperative
morphological and functional
configuration.
the main obstacles to the
development of robotics in
orthopaedic surgery?
I believe that, up to now, we have always
put "the cart before the horse". I come
from a robotics background, in which I
developed an active system devoted to
stereotactic neurosurgery. I have
subsequently changed my mind, as the
so-called "passive" navigation systems
offer a number of functional options - an
SURGETICS Station

added value whose limits cannot even
be suspected at the present time - and
solve multiple problems. Robotics,
initially used as a response to these
problems, now appears to be an error;
an error which is even harder to justify
in view of the high cost of these systems,
which are technically difficult to
develop. I think that, in the long term,
robotics will be an "instrumental
ancillary", in which navigation will
constitute the first level of
ancillary, although some of its
phases could possibly be
robotized, to ensure greater
precision and increased
security. Moreover, robots are
not purely "active", such as
Robodoc and Caspar robots,
but can also be semi-active, in
this case, the robot, often much
more compact, simply guides
the surgeon's movements, and
protects certain high-risk
zones.
ASN: A knee surgeon
does not have the same
concerns as a spinal
surgeon. You are
developing applications
for orthodontists, ENT
surgeons, etc. How do
you deal with these
multidisciplinary
requirements?
We are in contact with a wide range of
surgical specialties and we adopt a
pragmatic approach to this diversity. We
strive to find solutions to very concrete
and very specific problems in co-
operation with clinicians. Our
partnerships with surgeons at the
forefront of their field, and with
manufacturers of implants, allow us to
acquire all of the knowledge necessary
to develop our systems. An all-purpose
SURGETICS machine
obviously does not exist.
We have developed a
software and equipment
platform responding to all
of the generic needs of
surgery, but the
development of each application is
essential and differs each time, just as
the problems to be addressed also differ.
ASN: Who are your scientific and
clinical partners?
Our main scientific partner is the TIMC
laboratory, situated a few metres from
our premises, with its CAMSP
department directed by Jocelyne
TROCCAZ. We have exclusive rights to
about ten of this laboratory's patents, in
our fields of activity.
We have an increasing number of
clinical partners. For the moment, they
essentially operate in the Grenoble
region and mainly consist, in the field of
orthopaedics, of Professor MERLOZ's
team at Grenoble teaching hospital for
the spine, and Professor JULIARD's
team at the Clinique Mutualiste in
Grenoble.
ASN: What are PRAXIM's
objectives for the next five years?
Our objectives are to meet the growing
market demand by positioning ourselves
as one of the leaders in orthopaedic,
ENT, and maxillofacial surgery. We then
hope to establish our presence in other
markets as a result of technological
derivation.
ASN: And your objectives for this
year?
Our short-term objectives are to launch
our first products. 2001 is the year of
SURGETICS, particularly in the fields
of intranasal, dental and orthopaedic
surgery. Several applications for the
knee, in collaboration with various
industrial partners, will immediately
provide users with an open solution. We
will also launch a first product for spinal
surgery this year. ■
communication
PRAXIM
Stephane Lavallée and the SURGETICS Station
3D Matching of a statistical
model to the real anatomical
surface
(example of the Tibia)

THANK YOU FOR YOUR CONTRIBUTION !
WE WILL SEE YOU NEXT YEAR…
Photos taken from the
5TH
International
Argos symposium

communication
Fifth International Argos Symposium
SESSION One, "A Virtual Trip on
the Spine Planet," was devoted to
imagery. Mr. Leonard Fass (General
Electric) provided an overview of
innovations and future prospects in
spinal imaging, emphasizing that MRI,
CT scans, and standard X-rays are used
in a complementary way. MRI and CT
scan present certain advantages, such as
high contrast, direct axial imaging,
surgical operation control, multi-slice
reconstruction, and virtual endoscopy of
the spine. While CT scan offers images
of the bone and calcium, MRI is suited
to visualize bone marrow and spinal
nerves. For the time being, ligaments
and scar cannot be visualized with these
two techniques. For nerve imaging, it is
still necessary to use intravenous
contrast agents, which make these
techniques semi-invasive. Volume
rendering shows arteries and blood
vessels in relation to the spine. Mr. Fass
mentioned that improvements must be
made to eliminate artifacts in ultra-high
(100 micron) resolution. In the future,
the trend will be from closed MRI
systems, which offer better image
quality, to open systems, which are more
dynamic.
Professor Jacques De Guise of the
Imaging & Orthopedics Research
Laboratory in Montreal spoke on "3D
Imagery: Realism vs. Accuracy." He
reviewed various imagery techniques
for orthopedic surgery, outlining their
advantages, disadvantages, and potential
difficulties. Traditional CT scan
produces multi-slice images, but new
technology has led to spiral images and
voxels (3D data sets). The speaker
discussed the four possibilities using CT.
The first is the classical axial acquisition
(re-slicing), which provides 2D images;
it presents the advantage of being quick
and simple to use. One disadvantage is
that it requires data interpolation.
Second is MIP (maximum intensity
projection). This technique is most
appropriate for vascular pathologies; it is
also quick, simple, and gives 2D images.
Artifact is the main problem with this
technique. The third method described
by Professor De Guise is surface
rendering, which offers 2D-3D contour
detection, polygonal models, and
computer graphics. Surface rendering
provides visualization in real time and is
simple and quick. However, it requires
an enormous amount of data and
reproduces only the surface of objects.
The source of incongruities may be hard
to determine. Although the images it
produces are quite impressive, this
technique requires the presence of an
expert, is long and fastidious, and
involves a complex method of
automatization. Volume rendering, the
fourth possibility, involves projecting
the 3D data set onto the imaging plane
and offers the advantage of being a
virtual X-ray, allowing anatomic cuts for
teaching anatomy. However, it requires
a huge amount of data; it is operator-
dependent; it produces artifacts; and it is
computer-intensive. There is no direct
Fifth International
Argos Symposium:
A Spine Odyssey
January 26th, 2001 - Maison des Arts & Métiers - Paris
As the crowning event in a week dedicated to the spine, the Fifth Argos Symposium focused on the
use of technological innovations in spinal surgery. Dr. Christian Mazel opened the day's events and
welcomed Argos members and other participants.
Mr Leonard FASS (General Electric) Pr. Jacques De Guise, PhD

access to 3D geometry. The speaker
explained that biplanar radiography
could replace CT scans. It is very
precise and uses low-dose radiography.
This technique, however, is only a
surface rendering technique and
requires the assistance of an expert as
well as a priori information.
In conclusion, Professor De Guise
stressed that these are virtual images,
which may very well differ from reality.
One may rightly ask, "What is real and
what is virtual?" There have been
relatively few studies on the precision of
these techniques and their clinical
relevance (M.W. Vannier et al, Iowa).
The speaker concluded that there are
many 3D methods and no perfect
technique; the choice depends on the
context. For optimum precision, one
needs a large data set, time, and the
assistance of an expert.
After a wealth of information from an
engineering perspective, the next
presentations were given by clinicians.
Professor Jean-Claude Dosch outlined
the latest innovations and contributions
to diagnosis and new therapeutic
perspectives. In the field of digital
radiography, he reviewed conventional
X-ray techniques: CT, MRI, PET
(Positron Emission Tomography). Prof.
Dosch discussed clinical applications of
the above-mentioned techniques. They
are used for spinal trauma using 3D and
2D images. Multitissue imaging has few
applications currently. He stressed that
the clinical application of 3D images
essentially concerns the detection of
intervertebral dislocation and unilateral
luxation. He then reviewed clinical
examples using MRI imaging in
degenerative pathologies: myelo-MRI,
dynamic MRI, and in post-operative
diagnosis of infections. In his
conclusion, Prof. Dosch emphasized
how valuable imaging techniques are for
diagnosis and therapeutics; one may ask
whether France is lagging behind in the
acquisition of the necessary equipment.
These techniques are not 100% reliable
and surgeons should not forget
conventional techniques (X-rays). In the
future, and to reduce artifacts,
techniques can be combined. The panel
emphasized the complementary nature
of the various techniques. Clearly, one
cannot sacrifice precision for the sake of
image quality, regardless of how
beautiful the pictures may be.
Session Two focused on "The State of the
Art in Robotics and Spine Surgery." The
first speaker, Dr. François Laborde, is a
cardiac surgeon who heads an
experimental surgery laboratory in
which robots are used. The goal of
robotics in surgery is to improve the
surgeon's autonomy and offer
advantages for patients; the speaker
expressed the need for more progress
toward reaching these goals.
Dr. Laborde reviewed the three types of
robotic systems currently available
(Intuitive, Zeus, Caspar). The
advantages of mini-invasive surgery
using robotics for the patient include:
smaller incision, less pain, shorter
hospital stay, faster recovery, greater
patient comfort, etc. For the surgeon,
advantages are primarily improved
ergonomics, greater control, savings in
costs and time, etc. The main advantage
in using robots is automatic response,
image-guided positioning, and the
target-tracking system, in addition to the
high level of precision. Using robots
requires past experience with video
surgery plus dry and wet lab training.
Dr. Laborde warned that the learning
curve must definitely be taken into
account when a surgeon is considering
the use of robotics. The speaker also
addressed the ethical/philosophical
considerations related to this kind of
surgery.
In the next speech, "Is There a Robot in
the Operating Room?" Dr. Adrian
Lobontiu presented an intuitive robot
made by Intuitive Surgical (Mountain
communication
Pr. Jacques De Guise, Phd
Mr Leonard FASS,
Pr. Christopher Ullrich, MD
Pr. Jean-Claude Dosch, MD

Januar
Maison des A
Argos’ symposium
> January 31st, 2002
13h30 to 17h30
and February 1st, 2002
08h30 to 12h00
Free communications
> February 1st, 2002
14h00 to 16h00
The lumbar and lumbo-sacral
degenerative spine
6TH
Argos
As every year, the 6th ARGOS Meeting will
take place at the “Salons des Arts & Métiers”
in Paris. This beautiful private parisian man-
sion seems to adapt perfectly to the meeting spi-
rit. Indeed, it favours conviviality, exchange of
views and dialogue. The symposium will last
from Thursday afternoon to Friday Morning.
Friday afternoon will be devoted to free com-
munications.
To give the good indication of a lumbar or
lumbo-sacral fusion is the guarantee of a
good functionnal and clinical result. This is the
key point of the treatment. Several schools,
even philosophies are opposite in this field.
However, it is certainly possible to access to a
rather common attitude. That’s why we wish
to have the opinion of few of you to help us to
define easily what can be considered as the
“good indication”.
The second point that highly contributs to the
quality of the result is the surgery’s strategy.
Which levels are to be fixed? What kind of
fusion to do? These are important factors,
which will influence the results. The topic is
wide, source of many questions and examina-
tions. This year, we only wish to discuss the
indications and the surgery’s strategy in the
treatment of lumbar stenosis associated to an
adult scoliosis or/and or to an arthritic spondy-
lolisthesis, as well as in isthmic lysis and grade
one spondylolisthesis. The years 2003 and 2004
will allow us to study the other indications of
fusion as regards of the common or post-discec-
tomy low back pain, the disc herniation the
multi operated spine and high grade spondylo-
listhesis. We hope to have the pleasure to meet
you during these next meetings. ■
Lumbar a
which ind
In lumbar
in isthmic
Dr Philippe BEDAT
Dr Jean-Paul FORTHOMME
Dr Frank GOSSET
Dr Alain GRAFTIAUX
Pr Pierre KEHR
Dr Christian MAZEL
Pr Jean-Paul STEIB
Dr/Ing Alexandre TEMPLIER
Dr Richard TERRACHER
Scientific
committee :

www.argos-europe.com
y 31 and February 1st 2002
Arts et Métiers - 9bis avenue d’Iéna PARIS XVI FRANCE
International
s symposium
and lumbo-sacral fusions :
dications, which strategies ?
stenosis associated to spinal deformities,
c lysis and grade one spondylolisthesis.

communication
View, California). He showed two short
films to demonstrate the range of
surgical possibilities using the da Vinci
robotics system in cardiovascular
surgery (coronary bypass) and
laparoscopic surgery (hernia repair,
nissen procedure, adrenalectomy, etc.).
After the presentation, Dr. Christian
Mazel showed a film of himself
performing open surgery on the dura
mater of a lamb with a robot. Although
he said the experience was interesting,
this approach requires substantial
training before it may be useful for the
surgeon; otherwise robotics is too
complex to use and highly time-
consuming, and therefore of
questionable benefit for the patient.
Session Three, "Navigation in the
Pedicle," focused on surgery using
computer navigation systems. The first
speaker, Mr. Harry Freitag, presented
the "AESCULAP SPOCS" 3D
navigation system. This Surgical
Planning and Orientation Computer
System, developed in Germany has
applications in neuro and spine surgery
and ENT. It has dedicated functions for
virtual screw position planning and
surgical guidance for screw implantation
and provides real-time tracking of
instruments.
Prof. Pierre Kehr, the next speaker,
described his experience with the
SPOCS system. He was initially
enthusiastic but found it very time-
consuming in practice. He showed a
video of his team using the device
during a real operation, which he
commented upon for the audience.
First, patient CT data are transferred to
the SPOC device, one vertebra at a time.
Next, the surgeon must place six
landmarks per vertebra (superior and
inferior articular apophyses and two for
the spinal processes). The surgeon then
places the virtual pedicular screws,
calculating the entry/exit points, target,
angle, etc. The synchronization phase
consists of matching reality to the virtual
data that were fed into the system. Dr.
Kehr reported that he had to start each
step over more than once to ensure
proper virtual placement of the screws
before actual surgery. Once the
preparatory phase was complete, the
device enabled easy navigation.
The speaker stressed the learning curve,
once again. In addition, the system is not
intuitive and requires mastery of the
software.
Professor Philippe Merloz spoke about
fluoronavigation. The C-arm is a
commonly-used tool, but alone it does
not provide axial images and is often
responsible for errors in spine surgery.
Fluoronavigation uses the C-arm and
image-guided instruments, and
calibration target with embedded
LEDs, as well as a computer. Prof.
Merloz described pedicular screw
placement using a fluoroscope,
consisting of C-arm set-up reference
frame fixation; camera alignment; and
instrument calibration.
The speaker outlined the advantages of
fluoronavigation, which is a more
intuitive method: it does not require
pre-operative CT, and there is no need
to make a model or establish landmarks.
However, it requires manual data
acquisition.
Discussion of CT-based navigation and
fluoronavigation emphasized that for
greater efficiency, technicians should be
in charge of support and preparatory
steps and pre-operative scanning should
be standardized. The panel once again
stressed that the two techniques are
complementary and not antagonistic. In
the future, the combination of CT and
ultrasound will probably revolutionize
the field of imaging.
The afternoon session was devoted to
Internet and the medical practice. It
opened with Dr. Franck Schwab
presentation, "The Internet Experience
of a Surgeon" which he summed up
vividly: "Developing a website is like
fishing: it may sound easy, but it can be
a real challenge." Internet is
increasingly affecting all the realms of
our daily lives, health care included.
Today, 44% of Americans use internet
and 36% refer to it for medical
information. For a surgeon, what are the
benefits of creating a website? What
kind of resources are needed? What are
the options? What can we offer to
patients? Such were the questions
addressed by Dr. Schwab
(www.orthospine.com). The benefits are
numerous, since a website enables
individual physicians or groups of
physicians to provide specialized
information to the patients who would
otherwise consult other sources of
information — industrial or commercial.
The site can also provide practical
information on hospital location, hours,
answer FAQs (frequently asked
questions), offer extended patient
contact, etc.
Dr. Alexandre Templier then
Pr. Gérard Saillant, MD & Dr. Christian Mazel, MD
Pr. Pierre Kehr, MD
Dr. Franck Schwab, MD & Pr. Gérard Saillant, MD

A g e n d aA g e n d a4th Israeli Symposium on Computer
Aided Surgery, Medical Robotics and
medical Imaging
May 17, 2001, Tel-Aviv, Israel
Phone: +972-4-829-3264
Fax: +972-4-832-4533
E-mail: shoham@techunix.technion.ac.il
http://www.cs.huji.ac.il/~josko/isracas2001.html/
3rd International Conference on 3D
Digital Imaging and Modeling
May 28 – June 1st, 2001, Québec,
Canada
Phone: (613) 993-0414
Fax: (613) 993-7250
E-mail: 3dconf@nrc.ca
http://www.vit.iit.nrc.ca/3DIM2001/
4th International Pediatric Radiology
May 28 – June 1st , 2001, Paris ,
France
e-mail: strife.jl@chmcc.org & brunelle@necker.fr
http://www.ipr2001.org/
International Conference on Augmented,
Virtual Environments and 3D Imaging
May 30 – June 1st , 2001, Mykonos,
Grèce
Phone : +30.31.464160
Fax : +30.31.464164
E-mail : icav3d@iti.gr
http://www.iti.gr/icav3d/
The Fourth Combined Meeting of the
Orthopaedic Research Societies of the
USA, Canada, Europe and Japan
June 1 – 3, 2001, Rhodos, Greece
Phone : (847)698-1625 Fax : (847)823-4921
http://www.ors.org/
Medical Imaging and Augmented
Reality
June 10 – 12 2001, Hong Kong
Phone : (852) 2609-8433
Fax : (852) 2603-5024
Email : ttwong@cse.cuhk.edu.hk
http://www.cse.cuhk.edu.hk/~miar2001/
IX Mediterranean Conference on
Medical and Biological Engineering and
Computing
July12-15 , 2001, Pula, Croatia
Phone: +385 1 61 29 938
Fax: +385 1 61 29 652
E-mail: MEDICON2001@crombes.hr
http://www.crombes.hr/MEDICON2001/
International Society for the Study of
the Lumbar Spine
June 19-23, 2001, Edinburgh, Scotland
http://www.issls.org/
Computer Assisted Radiology and
Surgery
June 27 – 30, 2001, Berlin, Germany
Phone.: +49 -30- 314 73100 b
Fax: +49 -30- 314 23596
Email: hul@cs.tu-berlin.de
http://www.cars-int.de/
XVIIIth Congress of the International
Society of Biomechanics
July 8-13, 2001, Zurich, Switzerland
Phone: ++41 1 633 61 17
Fax: ++41 1 633 11 24
E-mail : isb2001@biomech.mat.ethz.ch
http://www.isb2001.ethz.ch/
25th Annual Meeting of the American
Society of Biomechanics
August 8 – 11, 2001, San Diego,
California, USA
Phone : (858) 534-3940
Fax : (858) 534-7672
E-mail: ocme@ucsd.edu
http://www.asb-biomech.org/
3rd Annual Meeting of the Spine
Society of Europe
September 4 - 8, 2001, Gotenburg,
Sweden
Phone: +46-31-342 34 05
Fax: +46-31-82 35 84
E-mail: Bjorn.Rydevik@orthop.gu.se
http://www.eurospine.org/Meetings/es.01.html
The 57th Annual Congress of the
H.A.O.S.T (Hellenic Association of
Orthopaedic Surgery and Traumatology)
Sept. 12 -16, 2001, Athens, Greece
Phone: +30 1 685 4156
Fax: +30 1 685 4187
36th Annual Meeting of the Scoliosis
Research Society
September 19-22, 2001, Cleveland,
USA
Phone : (847) 698-1627
Fax : (847) 823-0536
http://www.srs.org
The 1st International Symposium on
Measurement, Analysis and Modeling
of Human Functions
September 21 – 23, 2001, Sapporo,
Japon
Phone: +81-45-924-5654
Fax: +81-45-924-5684
e-mail: ISHF2001@ito.dis.titech.ac.jp
http://www.ito.dis.titech.ac.jp/ISHF2001/
BIOMECHANICA IV (Orthopaedic
Research Society)
September 23- 25, 2001, Davos Suisse
http://www.biosolutions.net/motion_analysis
/Biomechanica_IV.htm
4th International Conference on Medical
Image Computing and Computer
Assisted Intervention
October 14-17, 2001, Utrecht, Pays
Bas
Phone: +31 30 250 6695
Fax : +31 30 251 3399
E-mail: miccai@isi.uu.nl
http://www.miccai.org/
16th Annual Meeting of the North
American Spine Society
October 31st –November 3rd, 2001,
Seattle, USA
http://www.spine.org/
communication
Agenda

proceeded to describe the ARGOS
website, www.argos-europe.com. The
Argos website features the three main
focuses of Argos: communication,
training, and evaluation. The site lists
the association's offices, commissions,
organization chart, and contacts and
provides information about Argos-
sponsored events. The training section
offers a list of training centers which
host surgeons from the world over, and a
list of Argos partners.
The next speaker, Professor
Christopher Ullrich, addressed the
issue of information technology and
methods for storing, retrieving, and
distributing medical images. He
outlined the advantages and drawbacks
of five methods.
With film-based image dispatching and
interpretation, images are easily
disorganized and lost, and it is difficult
to dispatch them efficiently. Video
require a great deal of storage space and
is processed using toxic chemicals that
contaminate the environment.
Electronic image dispatching and
interpretation is fast, dependable, and
flexible. Images remain organized. This
high resolution medium can be used
with sophisticated software. However,
display equipment is expensive and this
method generates high infrastructure
costs. Other drawbacks include the fact
that this method requires skilled
technicians; equipment quickly
becomes obsolete; and sophisticated
computer tools can be intimidating and
counter-intuitive.
PACS is the buzzword that describes the
third approach. Prof. Ullrich explained
that PACS (Picture Archiving and
Communications Systems) are intended
to be used by a radiology department,
not an entire hospital, much less the
whole world. PACS offer easy
distribution and data exchange with
other hospital departments. However,
this system usually requires proprietary
software on each display computer that
accesses the system. Moreover, systems
may quickly grow obsolete and require
large bandwidths to handle ever-
growing data sets.
The fourth approach relies on Internet-
related developments. Universal web
browsers allow user-specific
applications; all upgrades come from a
central server; and multiple users can
access the system simultaneously. Due
to concern about data security, privacy
and security standards are already in
place (firewalls, SSL, VPN, etc.).
Application service providers are the
fifth and final option. With this system, a
«vendor» owns the computer and a
facility/hospital enters into a contract to
use it. The facility will use a given
vendor as long as the service provided is
satisfactory ; otherwise it can switch
around until it finds a satisfactory
vendor. The downside is a certain
degree of loss of local control by the
hospital or facility.
In his presentation entitled, "To evaluate
in order to communicate," Dr. Alexandre
Templier addressed basic issues such as:
Evaluation is a continuous and
collective approach; but what is its
purpose? One evaluates for the future,
but what is the future of orthopædic
surgery? Evaluation, as a continuous
and collective process, is an essential
part of the surgeon's responsibility as a
decision-maker. Dr. Templier
underscored the importance of the
continuity of assessment throughout the
entire clinical process. As the patient
goes through all the clinical steps, from
his first visit to the doctor to the
operating room, the physician is
constantly analyzing and evaluating:
from the pre-operative stages to surgery,
(consulting room, diagnosis, tests, X-
rays, etc.) to post-operative evaluation.
Depending on the result of surgery, the
surgeon must analyze the reasons for
success or failure. Post-operative follow-
up is thus a crucial stage of the process,
but surgeons still lack adequate
assessment tools. Secondly, Dr. Templier
underscored the collective aspect of
evaluation, allowing surgeons to become
familiar with each other's standards; this
means improving communication
between surgeons. To this end,
prospective multicentric studies can be
very useful. The future of evaluation,
according to Dr. Templier, may lie in
navigation, if image-guided surgery is
implemented by pre-operative
measuring and quantifying techniques.
Now the question is, will these new
techniques really benefit the profession,
or are they a passing fad? The future will
tell; nevertheless, one clear point is that
today's evaluation tools must be
clinically relevant, reliable, non-
invasive, and easy to use, with
reproducible results. Of course, these
technological advances will never
replace surgeon's experience and
scientific expertise, but their potential
should not be underestimated.
Ms. Isabelle Lucas Baloup, a lawyer
licensed to practice with the Paris court,
delivered a speech on "Internet in
medical and surgical practice in France"
from a legal viewpoint. She began by
asking, "Is the law the worst enemy of
surgical progress?" The Internet is
international, but each country has its
own laws. A physician's use of the
Internet in France is governed by
French civil and penal law, and the
medical profession's code of ethics.
French law will apply if the information
on Internet is available in France. ■
communication
Dr. Alexandre Templier, PhD
Maître Isabelle Lucas Baloup

ASN:Professor Gracovetsky, can
you describe the path that has
led you to devote your career to
the study of the spine?
SG: I graduated from the Ecole
Polytechnique Fédérale in Lausanne in
1968, with a degree in nuclear physics
and I also obtained a Ph.D. from the
University of British Columbia in 1971.
My meeting with Harry Farfan in 1974
gave me the opportunity to work in the
biomedical field. At that time, Harry was
at the heart of a renewed effort involving
a number of research scientists, such as
Alf Nachemson, which culminated in
the foundation, in Montréal, of the
International Society for the Study of
the Lumbar Spine which is now the
undisputed leader in this field. The
atmosphere was electric and I was
carried away by this "brainstorm". I then
spent about ten years trying to
understand the characteristics of a
"normal" spine, by means of
mathematical simulations and analyses
in the pathology laboratory. The many
contradictions between experimental
data and the theories of the time
gradually led me to reject many widely
held beliefs and, in 1983, led to the
formulation of a hypothesis combining
the essential aspects of the work of many
authors into a coherent theory able to
explain the structural and functional
development of the locomotor
apparatus. This was called the "Spinal
Engine" theory, which was the subject of
numerous criticisms, but has never
really been replaced. It therefore
appears to partially correspond to
reality. This theory led me to develop
instruments to measure clinical spine
function. One of these instruments,
called a "Spinoscope", led to the creation
of a company that operated for a number
of years.
ASN:Can you describe your work
environment before your recent
retirement?
SG: I was working in a company called
"Spinex", which comprised a very large
research department, exclusively
designed to develop commercial
applications of our research. Work
started at the Concordia University in
Montréal (Faculty of engineering and
computer sciences), where I was a
faculty member for 27 years. Today, I am
more specifically interested in the
medical decision process, i.e. to
understand the elements which lead
doctors to arrive at a diagnosis for the
cause of our eternal nemesis, low back
pain. Since 1992, my main areas of
interest have been expert systems and
structuring of knowledge in order to
more clearly understand why a clinician
adopts one treatment strategy rather
than another. I have tried to integrate
spinal function as measured by various
instruments, with more conventional
methods such as radiology, pain
assessment and clinical observations in
evaluation
The Spine Engine
Interview with Professor
S. Gracovetsky
Professor Serge Gracovetsky kindly granted us this interview while he was
in Amsterdam for a university seminar on the biomechanics of the locomo-
tor apparatus.
“The Spine Engine: A unified theory of the Spine?”
“If the leg cannot rotate the pelvis, then what rotates the pelvis ?? It has to be the spine.
But how ??”
Human Gait
What we
want
What we
have

evaluation
The Spine Engine
order to establish a multidisciplinary
approach.
ASN:You mentioned Professors
Farfan and Nachemson with
whom you worked. In what
context did you conduct these
collaborations?
SG: My collaboration with Harry Farfan
involved 7 to 8 hours a week and lasted
approximately from 1974 to 1985. We
conducted a large number of studies and
published many papers together. Harry
had exceptional intuition and vision,
extending well beyond conventional
medicine. He believed that spinal
problems were due to excess mechanical
torsion. Nachemson, an impulsive and
brilliant man, saw most spinal problems
in terms of disk compression. When
Farfan and Nachemson were on the
same podium at any congress organized
anywhere on the planet, you could be
sure of a fierce, and well-reasoned,
battle of wits. My own work was greatly
influenced by the jousting between
these two exceptional personalities. The
spinal engine theory actually represents
a compromise between these two
extreme points of view supported by
Farfan and Nachemson. This theory
demonstrates the irreducible link
between compression and torsion
phenomena which are an integral part of
the principle of human locomotion.
ASN: What are the general
principles of your Spinal Engine
theory?
SG: The main idea is that locomotion is
an activity which takes precedence to all
other activities. The individuals of a
species must move in order to survive
and enjoy vital bodily freedom.
However, we need to define certain
limits to this hypothesis. According to
this theory, the animal must travel from
point A to point B by consuming a
minimum of energy, in a constant
gravitational field, with, as a corollary,
that while walking, the various
structures (bone, ligaments and muscles)
must be submitted to a minimum of
stress. Anatomy therefore emerges as
the solution and not the given parameter
of the problem.
All of the possible solutions to this
problem have led to many anatomic
configurations, and our anatomy is only
one expression of these numerous
possibilities. The human body as we
know it today, is mainly the consequence
of the need to effectively walk on two
feet in a constant gravitational field. The
spinal engine oscillates within this
gravitational field.
ASN: What, then,is the role of the
spine in the locomotion?
SG: I consider the spine to be the
"primary" engine, in the etymological
sense of the word. This primary engine,
so obvious in our ancestors the fish, has
not travelled towards the lower limbs
over time, although its role has become
more obscure and may appear to be
secondary to the role of the lower limbs.
However, this logic is faulty, as we are
able to "walk" on our knees with
relatively little adaptation, which
demonstrates that our legs are not truly
essential to human locomotion. A
wooden leg is just as effective. It would
be conceivable to cut the femur one
centimeter above the knee without
significantly affecting walking. This
therefore raises the question: how far
can we cut the femur before affecting
human locomotion. The answer is that
the lower extremity can be completely
«Are the legs really
necessary ???»
Compression Torsion
“Pathology gives data on how the spine is used
in life. Any explanation for human gait must
incorporate these pathological findings.”

removed without interfering with the
primary movement of the pelvis. This
statement may appear somewhat
excessive, but it is supported by the
facts.
Prof. Gracovetsky then showed
us a film on his computer,
representing a man with no legs
and no stumps walking by
successively advancing his
ischial tuberosities, as if he had
legs. The spinal mechanics then
appeared to be the engine of this
locomotion, which appeared to
so closely resemble normal
walking.
It is obviously preferable to have legs,
but they only amplify the movements of
the pelvis, and their functional role
remains secondary.
ASN: Can you briefly describe
the interrelations between the
spine, the pelvis and the lower
limbs?
SG: The spinal engine is quite obvious
in the case of a snake or a lizard, but
when a high level of power needs to be
developed, the muscles of the trunk are
insufficient. To increase the volume of
energy-generating muscles, they had to
be displaced outside of the abdominal
cavity, to the legs. The first role of the
legs is to support the energy sources,
which enable us to move at high speeds.
However, rotation of the pelvis (as the
pelvis rotates around a vertical axis
when we walk) with muscles which
draw the pelvis downwards leads to a
problem of efficacy. This problem is
resolved by using the earth's
gravitational field as the site of
intermediate storage, in which the
muscle energy released by the legs with
each step is temporarily stored and then
recovered during the monopodal stance
phase. This energy impulse then
ascends up the leg and is filtered by the
leg, so that it reaches the vertebral
column with the appropriate phase and
amplitude. The spine can therefore use
this energy to mobilize each
intervertebral joint, and to rotate each
vertebra and the pelvis in an appropriate
fashion. Movement of the vertebral
column, especially its axial rotation
movement, is therefore derived from the
hip extensor muscles.
ASN: What happens in the static
position?
SG: The anatomic structures which
connect the spine to the lower limbs are
considerable. Take biceps femoris or the
hamstrings, for example; the force
generated by the hamstrings are
channelled by the sacrotuberous
ligament, which controls longissimus
lumborum and latissimus lumborum
situated on either side of the lumbar
spine. Part of the sacrotuberous
ligament then controls the iliocostalis
thoracis muscle up to the superior part
of the thoracic spine. Two transverse
planes (the right hamstrings control part
of the muscles connected to the left side
of the thorax and vice versa) constitute
another direct link between the
hamstrings and the superior part of the
thoracic spine. Another important
linking element consists of gluteus
maximus which crosses the medial
aspect of the spine to be attached to
latissimus dorsi, which controls arm
movements. All of these connections
form a sort of cross-pyramid of the back,
which ensures very strong mechanical
integrity from the upper limbs to the
lower limbs.
ASN: Can you place the
configuration of the human
locomotor apparatus, as we
know it, in the context of
evolution?
SG: The presumed starting point (as it is
only a hypothesis) is that primitive fish,
450 million years ago, moved in the
same way as modern fish, i.e. by a lateral
inflection movement of the spine. Fish
which subsequently ventured onto dry
land were faced with several problems,
the first being to move by planting their
fins into the mud by means of an
alternating movement. This axial
rotation movement combined with the
lateral flexion movement resulted in the
movements of flexion and extension.
Thus, the simple need to move over
small pebbles led our fish to invent
flexion and extension movements. This
same flexion-extension movement
subsequently allowed galloping and the
development of the lower limbs, as the
para-axial muscles gradually moved
outside of the abdominal cavity to
become hamstring muscles, in order to
increase the brute power available for
locomotion. Some of these vertebrates
subsequently returned to the sea, while
evaluation
The Spine Engine
" Only half the available muscle power is used. Each step
advances the animal by one shoulder width "

evaluation
The Spine Engine
retaining their capacities for flexion-
extension movements acquired during
their "stay" on dry land. These animals
are marine mammals, which also
breathe in a very different way from fish.
The hypothesis that these marine
mammals are descendants of terrestrial
quadrupeds, at their turn descended
from marine animals is now generally
accepted.
The inevitable increase in the muscle
mass of the legs then made an upright
posture possible. Finally, the need to
advance and therefore to pivot the pelvis
in two alternating ways, gave rise to the
spinal mechanics that we now know
today.
ASN: When we listen to you
speak, we have the impression
that you are neither a doctor, nor
a biomechanical engineer. How
would you describe yourself?
SG: I have never thought about it, but I
am certainly proud to have contributed
to solving certain problems. The
solutions that I proposed were the
subject of a great many criticisms,
sometimes more destructive than
constructive, but in the final analysis,
the need to reply to these criticisms was
a major element that helped me to
present my ideas more rigorously. It is
true that I sometimes felt that certain
criticisms did not always reflect a
disagreement based on good faith, and I
sometimes answered in a way that I now
regret.
ASN: Don't you think that your
theory was the subject of so
much criticism because you did
not belong to any clearly
identified discipline?
SG: I was not trying to solve the
problem of human locomotion. Many
other scientists more erudite than
myself possessed the necessary
elements to converge on this vision of
the spinal engine. Lowett in 1898 (a
century ago!) came close to this solution,
but did not take the last step, as it
appeared far too incongruous. I can also
think of people like Farfan, Nachemson,
Pope, Winter and many others. All in all,
it wasn't my place to find this solution,
but rather all these other people who
had infinitely more knowledge and
experience in relation to the spine. I felt
a need and I saw a gap in the logic of
our knowledge at the time. I was very
young when I entered this field (I was
appointed Professor at Concordia
University in Montréal in 1970), with a
certain independence of mind, and I
started by studying everything that my
predecessors had done. It took me 3
years to review thousands of
publications on the subject, which I
refined to 600 or 700 papers that I
considered to be important. There were
papers all over my office: on the floor, in
cabinets. I was therefore faced with
strong and often divergent opinions
voiced by honest people and I asked
myself how I could incorporate all of
these diverging views into an all-
encompassing theory, a sort of unifying
theory, as is often the case in physics.
Then, one day in January 1983, I
suddenly had a vision : I saw the spine
walking, a sort of slow-motion film. I
then had to formulate this vision into a
theory which was mathematically sound
and publish it, which I did for the first
time in 1985.
ASN: What are your current
projects?
SG: I made a lot of errors in the way in
which systems for the diagnosis of spinal
diseases should be designed. I fought for
many years to promote the use of a
measurement platform, which can be
greatly improved. When I started, about
twenty years ago, computers were very
slow, and measurement systems were
relatively inefficient. Currently available
solutions will inevitably integrate digital
“Solution: Change locomotor design to advance by one body length at each step”
“Lordosis is a unique feature of the human
spine”
“Lateral bending with lordosis induces an
axial torque”

imaging, slightly more advanced tools
for the assessment of pain, some of the
patient's psychological aspects, and
function. This should provide a more
accurate description of the patient,
which will obviously not be perfect, but
which, in any case, would be better than
the system available at the present time.
The decision to perform surgery and
evaluation of its impact on all of the
locomotor apparatus are essential, and I
am going to continue to patent several
ideas and continue in this direction.
ASN: ARGOS is above all a
network of orthopaedic surgeons
and neurosurgeons. Do you have
a special message for our
members and readers?
SG: The diagnosis of spinal diseases,
especially low back pain, is problematic
in at least 90% of cases. Nevertheless,
the current healthcare system expects
the doctor to find a permanent solution
to an insoluble problem. Health
authorities need to recognize that low
back pain is a difficult condition to
diagnose, and provide appropriate
resources to help the medical
profession. In my opinion, fees for
medical procedures concerning low
back pain should be considerably
increased so that the doctor can spend
the necessary time to establish the
preoperative and postoperative
diagnoses using appropriate tools, while
maintaining the same level of income. ■
evaluation
The Spine Engine
“The leg transfers the heel strike energy to
the spine. It is a mechanical filter.
The knee is a critical part of that filter
Improper energy transfer will affect spinal
motion
Functional assessment of the spine ought to be
part of the assessment of knee surgery”
“The spine is an engine driving the pelvis
Human anatomy is a consequence of function.
The knee cannot be tested in isolation.
It is part of the overall function and purpose
of the musculoskeletal system”
Contact
Information:
Serge Gracovetsky
gracovetsky@videotron.ca
209 Dauphine
St Lambert QC
Canada J4S 1N3
Serge Gracovetsky wishes
to acknowledge the
considerable contribution
made by numerous
individuals: N Newman,
M Richards, S Asselin,
V. Vidovic, ...

Proximal Facet Preservation i
using a new OMNI
Preliminary North A
W.B. Rodgers, M.D. (Jefferson City, MO)
evaluation
OMNI-AXIAL Connector
Introduction
DAMAGE to the cephalad facet joint
remains one of the technical
difficulties arising from transpedicular
spinal fixation systems. We describe a
novel OMNI-AXIAL screw-rod
connector for the SCS/CLARIS Spinal
Clip instrumentation system that allows
greater offset from the joint and may
decrease late facetal degeneration and
resultant post-fusion back pain.
Preliminary North American results of a
consecutive series of eighty lumbar
instrumentation procedures (min f/u 3
months) using the new connector are
reported.
Methods
Static and fatigue laboratory testing
were performed using the Cunningham
Protocol on the OMNI-AXIAL
connector. Static testing consisted of
standard sub-construct and four
screw/connector-rod construct flexion
studies on the Instron 8511. A 25-mm
flexion arm was used with loads applied
at 13 N/sec for sub-construct flexion. A
45-mm lever arm between load
directions and arms with a 76-mm
superior-inferior screw distance
comprised the four screw/connector-rod
flexion testing. Comparisons were also
made to existing implant systems.
The OMNI-AXIAL connector was
subsequently used as the cephalad
screw-rod connector in a consecutive
series of 80 lumbar fusion procedures.
Fusions were performed for
spondylolisthesis, degenerative disk
disease, recurrent herniated nucleus
pulposus, scoliosis, neoplastic and
metastatic disease, and failed ALIF.
Forty-two patients had undergone prior
lumbar surgery and nine had had prior
instrumentation. Fifty-nine patients
were actively abusing
tobacco.
Three patients had
simultaneous anterior
fusion procedures.
Autogenous iliac crest
graft was used in all
cases except two.
Demineralized bone matrix
(ALLOMATRIX, Wright Medical
Technology Inc., Memphis, TN) and
cancellous allograft was used to augment
the autograft in sixty-four procedures.
Calcium phosphate derived from coral
(ProOsteon, Interpore-Cross Int.,
Irvine, CA) was used to augment the
autograft in eight cases.
Undesired propagation of fusion
(pseudarthrosis) with proximal
facet damage.
Revision. Note proximal
facet preservation.
Case report
43 yo F, 157 cm, 120 kg, gr III
spondylolisthesis
Index Procedure:
L5-S1 fusion with reduction to gr I
Outcome:
9 days post, L5 pedicle fx during
physiotherapy
S1 screw failure
Secondary Procedure:
Revision to L4-S1 fusion
Technical Point:
Reduction requires 2-level fusion
Divergent alar screw augments sacral fixation

n Lumbar Fusion Procedures
-AXIAL Connector
merican Experience
and David R. Lange, M.D. (St. Louis, MO)
evaluation
OMNI-AXIAL Connector
Results
Sub-construct testing
revealed rod bending (at
mean 53 daN load) prior to
any rotational slippage of
the connector. Four
screw/connector-rod testing
yielded 63 daN loads to
without any connector
movement. Two samples
were fatigue tested at
5,000,000 cycles with 20
daN load.
Preliminary clinical results
(min 3 months, range 3-12
months) have been
encouraging with routine
progression toward fusion
and no complications
related to the new
connector.
Conclusion
The SCS/CLARIS Spinal Clip
instrumentation system OMNI-AXIAL
connector permits caudal displacement
of the rod-screw interface. This
translation coupled with the narrow
diameter of the transpedicular screw
post permits proximal construct fixation
with minimal damage to the cephalad
facet. Proximal facet preservation may
diminish later post-fusion back pain.
March 2001 - N° 3 ARGOS SpineNews 41
Complications
Seroma 2
Deep Infection 1
Hardware failure 1
Demographics
Age(mean) 54.1 yrs
Male 47
Female 33
Tobacco 59
Prior lumbar surgery 42
Prior instrumentation9
Diagnosis Primary Secondary
Tumor 4
DDD 28 24
Spondylolisthesis 20 5
Gr I 10, Gr II 7, Gr III 3
Rec HNP 11
Failed ALIF 2
Pseudarthrosis 8 3
Fracture 1 2
Scoliosis 6
Stenosis 31

The first biomedical
applications of shape memory
alloys (SMA) appeared 20
years ago. Since then,
researchers have been working
on the expanded properties of
these alloys, engineers have
exploited them to develop new
medical devices and surgeons
have spread innovative
surgical techniques throughout
the world.
AS it is now well-established that
almost 80% of the world-wide
innovative technologies are described in
existing patents, it seemed interesting to
summarize these 20 years of research
and development through a
retrospective study ofthe patents issued
in this field since 1978.
We will see that specific analysis applied
to a patent database can give precise
technologic and market trends. The
following statistics have been extracted
from WPI database (Word Patent Index)
which covers more than 20 million
patents issued in 40 industrialized
countries for 20 years.
Industry segments
We have found that 3695 patents have
been published on SMA since 1978,
among which 365, exactly 10%, dealwith
medical applications.
Furthermore, the International
Classification of Patents reveals which
specific areas are covered by these 365
patents. Among the 3 main biomedical
fields of application of SMA, the
breakdown is:
Orthopedics cardio vascular dental
45 % 44 % 11 %
Tab.1 : Percentage of patents on various
medical applications of SMA
Publication years
The evolution of the number of patents
per year gives valuable information
about the maturity level of a technology:
depending whether the number of
patents is increasing or decreasing, it
means that the technology involved is
either innovative or has reach the limit
of its evolution.
Here, the number of patents is
constantly increasing since 1982, which
proves that the biomedical use of SMA
is still growing.
Priority countries
The priority country is the first country
of publication of a patent. The
distribution of priority countries gives a
good indication of the leading nations in
a specific technology.
It shows the overwhelming leadership of
Japan and United States, with 144 and
132 with first publications respectively.
Designated states
The designated states are the countries
where a patent is extended between 12
and 18 months after its first registration.
This gives a good trend of the potential
economic markets as seen by the
companies who publish these patents.
It seems that the market is quite
balanced between North America
(US+CA – 197 patents) and the Pacific
area (JP+AU – 227 patents) and that the
European market is considered far less
important (DE+FR+RU+GB – 111
patent).
Conclusion
This retrospective study based upon
patents’ statistical analysis highlights the
evaluation
Shape-memory alloys
Retrospective study on medic
applications of shape-memor
Fig.1 : Evolution of the number of patents per year

trends followed by SMA in the
biomedical field :
- Japanese and North American
leadership
- increasing development for more than
15 years.
It can be concluded that despite
manufacturing difficulties, relatively
high cost and severe market regulations,
shape-memory alloy applications are
successfully finding their way to impact
a growing number of medical devices.
al
y alloys
Fig.2 : Distribution of priority countries
considering the number of patents published
Fig.3 : Designated countries according to the
number of patents extended
Anne Villeneuve
Economic Intelligence Department
Manager
INNOTECH, Technological
Resources Centre
221 avenue du Pdt Wilson,
93214 St Denis la Plaine cedex,
France
ARGOS News
ARGOS Member Card
Thanks to all ARGOS members, the 5th ARGOS International Symposium on the
new technologies dedicated to medical practice had a tremendous success in terms
of exchange between participants as well as for the quality of the communications
presented.
To celebrate this event, we are pleased
to offer you the ARGOS Member Card.
This card represents first of all a sign of
our gratitude but also the recognition of
your membership. This strictly
personal card (renewed every year) can
be used as a badge for our meetings
and it also guarantees certain
advantages to ARGOS Members:
• The access to our private forum on
the ARGOS Web Site (www.argos-europe.com)
• 20% to 30% discount on car rent with AVIS for your professional and personal use
all over the world.
This is only the beginning of a longer list of advantages the ARGOS board are just
about to negotiate for you with several international groups.
Spinal Column Pathology Association of Argentina : new authorities
We are pleased to inform you that from March 21, 2001 new authorities will be
taking office at this important Argentine medical institution. Dr. Horacio Sarramea
will be conducting the Association's new stage of management as its President.
First ARGOS Belgium meeting
The first ARGOS Belgium Meeting was held in Mons, Belgium, on April, 21st 2001
under the presidency of Dr Henri Costa, ARGOS Belgium President.
The theme of this meeting was: "Surgery & radiography of the lumbar spine : state
of the art".
ARGOS Italian Office
The ARGOS board is pleased to inform you that a new ARGOS office is now open
for you in Italy.
ARGOS Italian Office
Via Capecelatro, 81
20148 Milano MI
Italy
For more information, please contact the ARGOS Italian office secretary
Gina Menegazzi
Phone/ Fax: + 39 02 36 50 84 19 - argos@fastwebnet.it
Updated E-mail addresses
For a more efficient communication between the ARGOS board and the ARGOS
members, please send your e-mail address to the ARGOS secretary:
Marjorie Salé – ARGOS Secretary
Phone: +33 3 21 21 59 64 - Fax: +33 3 21 21 59 70 - marjorie@argos-europe.com
Please feel free to contact us whenever you have an interesting topic you
would like us to write about in our journal.
Alexandre Templier Anca Mitulescu
Editorial Director Editor in Chief
a.templier@argos-europe.com anca@argos-europe.com

ASN : Mr. Wolf, could you give us
some information about the
Technion and the Robotics-lab in
the Mechanical Engineering
Department (history, structure,
direction, activities) ?
AW : The Technion’s campus is located
in the beautiful city of Haifa,
surrounded with natural forest of the
Carmel mounting, watching the Haifa
bay. Technion has been established after
some years of intense pioneering
activities, among which Prof. Albert
Einstein was deeply involved. the
Technion opened its doors in 1924,
becoming Israel’s first modern
university (Prof. Albert Einstein was the
President of the first Technion Society).
The first undergraduate class consisted
of 16 students in two areas of
instruction; Civil Engineering and
Architecture. During the years the
Technion has broaden its research fields,
and today, it contains 19 faculties, 40
research centers, 11 research institutes
and 15 centers for excellence. Statistical
data from the years 1999-2000 imply
that there were 12,700 students learning
at the Technion (the number is growing
and is expected to reach 15,000 by the
year 2004).
The faculty of Mechanical Engineering
was one of the first faculties established
(1948), its aim is to prepare students to
deal with challenges in such a way as to
enable them to take front line positions
in developing technologies in all
industrial fields as well as dealing with
advanced computer-aided technologies.
The student receives a strong
foundation in basic subjects such as:
mathematics, physics, computers,
dynamics, thermodynamics, flow theory,
strength and control theory. The faculty
offers a number of areas of specialization
which include a varied list of elective
courses, such as: advanced design and
manufacturing, robotics, mechatronics,
electro-optics, computer systems,
micromechanics, energy, automation,
control nuclear energy etc.
The robotic laboratory is one of twelve
laboratories in the J.W. Ullman Center
for Manufacturing and Robotics (Head:
Prof. Moshe Shpitalni). The head of the
laboratory is Prof. Moshe Shoham. The
robotic lab focuses on developing
analytical and mathematical tools for the
design and analysis of robots in general.
Few years ago, we were one of the
pioneer groups to specialize in special
types of robots called parallel robots.
ASN : What are your current
projects in computer-aided
orthopaedic surgery ?
AW : We have several projects in our lab
regarding medical applications. At the
beginning, in order to examine the
feasibility of using a robot manipulator
guided by a pre-operative Computer
Aided Design program for medical
applications, a surgical tool and a force
sensor were attached to an existing
commercial robot . Based on the pre-
training
Technion’s Robotic Lab
Orthopaedic Surgery &
Robotics at the
Technion’s Robotic Lab
Alon Wolf (M.Sc), PhD Student in the Robotics Lab at the Mechanical Engineering Department of
the Technion (Israel Institute of technology). In this article Mr. Wolf gives us some input about
current projects, and new developments of the robotics lab. His particular work is focused on spi-
nal surgical procedures, which could be usefully assisted by robotics technologies. The design of a
micro-robot for spine surgery is in progress.
Bone shape by
a robot to fit
an implant for
total knee
replacement
Pre-operative planner for total knee
replacement

Argos SpineNews 2

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