Argos SpineNews 3

October 2000

News from the world of Spinal surgery and biomechanics

Focus on :

Discover the worldof nanotechnologies

A new bipedicular implant

Etienne-Jules Marey :the eye of biomechanic

New trends incomputer-assisted surgery

Interview of Pr FrançoisLavaste - Part 1

ENSAM BiomechanicsLaboratoryENSAM BiomechanicsLaboratory

T H E O F F I C I A L A R G O S P U B L I C A T I O N

communication

Interview of Professor François Lavaste -LBM Paris - Part 1

events

Inaugural meeting of ARGOSArgentina

Expo-Intermedica

7th seminar of spinal biomechanics,Poros Greece

internet

Web review

science

Discover the fantastic worldof nanotechnologies

evaluation :

A new bipedicular implant

technologies

New trends in computer-assistedsurgery

history

Etienne-Jules Marey :the eye of Biomechanics

focus on

The center for medical roboticsand computer assisted surgery atUPMC Shadyside andCarnegie Mellon UniversityPittsburg USA

clinical cases

Degenerative spondylolisthesisassociated with lumbar stenosis

Lumbar canal stenosis and instability

technologies

Nobel Prize Winner, Pr Georges Charpakcontribution to medicine 44

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TTaabbllee ooff ccoonntteennttss

October 2000

News from the world of Spinal surgery and biomechanics

For more information, see next page and get in touch with your local distributor.

Centre Hospitalier de l’Université deMontréal

1560 Sherbrooke Est Str.Montreal (Qc)

CANADA H2L 4M1Phone (514) 281-6000 #8720

Laboratoire d’imagerie, de visionet d’intelligence artificielle (LIVIA)

École de technologie supérieure1100 Notre-dame West Str

Montreal (Qc)CANADA H3C 1K3

Phone (514) 396-8800 #7675

Biomechanics - biomaterialsresearch group

École PolytechniqueCP 6079 Succ. Centre-ville

Montreal (Quebec)CANADA H3C 3A7

Phone (514) 3940-4711 #4198

Industrial collaborations :GERMANY : Telos

CANADA : Arthrolab, BiOp,Orthomedic, Zimmer

FRANCE : ARGOS, Eurosurgical, CeraverUSA : Sofamor Danek,Proctor and Gamble

Funding :NSERC, FCAR, FREOM, FCI, FRSQ

University collaborations :Biomechanics laboratory

of ENSAM (Paris FRANCE)LIS3D & Hôpital St-Justine (CANADA),

University of Bochum (GERMANY)

MedicalImaging

2D/3Ddigitalimaging

processing,3D models and

reconstructions,low radiation

multiplanar imagery

Clinical studiesDiagnostics,

evaluation ofprosthesesandorthoses

MedicalImaging

2D/3Ddigitalimaging

processing,3D models and

reconstructions,low radiation

multiplanar imagery

Clinical studiesDiagnostics,

evaluation ofprosthesesandorthoses

BiomechanicsStudy and modeling of

joint function, pathology,prosthetic replacement

BiomechanicsStudy and modeling of

joint function, pathology,prosthetic replacement

The Montreal Imagingand Orthopaedics

Research Laboratory

Research center of CHUM Montreal Canada

Circ

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Rea

ding

Ser

vice

Car

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( )EDITORIAL STAF

Editor in chiefAlexandre Templier, PhDProduction/Art director

Karim BoukarabilaBoard of editors

the ARGOS committeeWriter/Translator

Patrick Bertranou, MDBlake W. Rodgers, MDCarl Stéphane Parent

Philippe StraussAlexandre Templier

Assistant publisherCarl Stéphane Parent

ARGOS COMITTEES

Communication Committee :

Patrick Bertranou, MDPhilippe Bedat, MD

Henri Costa, MDPierre Kehr, MD

Charles-Marc Laager, PhDPierre Soete, MD

Training Committee :

Jean-Paul Steib, MDJean-Paul Forthomme, MD

Franck Gosset, MDFrançois Lavaste, PhDRichard Terracher, MDJean-Marc Vital, MD

Evaluation Committee :

Wafa Skalli, PhDJacques De Guise, PhD

Michel Dutoit, MDAlain Graftiaux, MD

Henry Judet, MDChristian Mazel, MD

Tony Martin, MD

EDITORIAL

HEADQUARTERS

ARGOS64, rue Tiquetonne

75002 Paris FRANCEPhone (33) 3 21 21 59 64

Fax (33) 3 21 21 59 70

ARGOS SpineNews circulation:over 7000 biannual issues

by direct mailing to surgeonsand spine professionals around the world.

Advertising sales:Please contact

Alexandre Templier [email protected]

Fax +33 (0) 1 42 33 06 62

EEddiittoorriiaall

October 2000 - N° 2 ARGOS SpineNews 7

ARGOS Members and Friends,

The first issue of ARGOS SpineNews attempted

to respond to a growing need for communication within

the international community of spinal surgeons, engineers,

researchers, and business people. We hope to produce an

orthopaedic journal for those working in spine-related technologies,

as well as a reader-friendly research newsletter. The ARGOS

Committees and we would like to thank you all for being so

enthusiastic about this Journal. Now the train is on its way,

and we will attempt to make the trip as pleasant as possible.

If you have any requests or suggestions to improve this

journal, please send it to our editorial headquarters.

We will do our best to make this journal Yours.

Before you start on this issue however, let us remind you

that the 5th ARGOS International Symposium in Paris

on January 26, 20001, will accept only 250 registrations.

If you have ever attended this event you know that it has to keep

its original size to preserve what makes it special, so please, don’t

forget to register as soon as possible. If you have never attended,

you definitely have to go! Open-minded collegial discussions

of topics at the forefront of clinical practice and

laboratory research in a friendly atmosphere

are not so frequent these days…

So come and join us as we expand the Spine Network!

Warmest regards.

Alexandre TEMPLIERARGOS General Manager

Editor in Chief

Christian MAZELARGOS President

In line with our objective toencourage dialogue, especially

between surgeons andbioenginners, we propose, inthis issue, the first part of an

interview that FrançoisLavaste very kindly grantedus. Can you imagine anyone

better informed than thedirector of the LBM himself to

help us to more clearlyunderstand biomechanics and

the work conducted in thelaboratory that he directs?Meeting with a fascinating

and fascinated man.

Pr François Lavaste, can you giveus a definition of biomechanics?

Biomechanics is the application of thelaws of mechanics to the study of themovement of the human body. Thehuman body is considered to be amaterial system in the broadest senseof the term. A system which containssolids, deformable bodies, and fluids.

In contrast to the mechanics of mate-rial systems, we do not work on inertcomponents since the components inbiomechanics are living and their cha-racteristics evolve over time. Let’stake the example of bone tissue: it agesand presents phases of remodelling asa function of the stimuli to which it issubmitted. Furthermore, in biomecha-nics, the same component can present

very different mechanical characteris-tics from one individual to another.Biomechanics includes structuralmechanics when studying the skeleton,fluid mechanics when looking at thecirculation of blood and other bodyfluids and thermodynamics wheninvestigating the process of energytransformation from inspired oxygenthrough the metabolic pathways toexhaled carbon dioxide.

Thus we study all aspects of the circu-lation, mechanical control by muscles,and the physiology of movement.Regulation systems and psychologicalaspects are not taken into account.

Do you think that the science ofbiomechanics can be dated to aspecific discovery?

8 ARGOS SpineNews N° 2-October 2000

Interview of Pr. François Lava

communicationWhat is Biomechanics ?


I don’t think so. The first woodensplints date to antiquity. The use ofmechanical structures to stabilize afracture constituted an early applica-tion of the principles of biomechanics.These practical procedures were thengradually enriched by basic science tofinally constitute the discipline nowknown as biomechanics.

Middle age wooden external prosthesis

Who were the main people whocontributed to the developmentof biomechanics?

The people that I know are mostlyEuropeans. Pauwels always seems to bequoted as the first example of a biome-chanician, but we should also mentionone of his students, Maquet. Pauwelswas both a surgeon and an engineer. Hestarted to apply the laws of mechanicsto his surgical practice in the 1930s.

Was he already aware of theinteractions between biomecha-nics and surgery?

Pauwels had a very mechanical view ofthe human skeleton and the body’sphysiologic mechanics. His surgicalpreparation was always based onmechanics.

You also mentionedone of his students?

Yes, Maquet applied Pauwels’ conceptsto the study of lower extremity move-ment. He can be considered to havebeen trained by Pauwels. These twopioneers cemented the relationship ofbiomechanics and orthopaedics. At theend of the 19th century, many scien-tists, such as Marey, were interested inkinematics, the study of movement.

Their research was based on the crea-tion of specific devices that were ableto mimic the movements of the upperlimbs and other body parts.

These machines were reminiscent ofthose developed by Georges Demeny(one of the inventors of cinema). Marey,for example, used this type of appara-tus, i.e. a photographic chamber contai-ning mobile systems and shutters toobtain images every one-tenth of asecond, to study the movements of abird’s wings. Braun and Fischer exa-mined human gait for milittary purposeby trying to optimize the gait ofPrussian soldiers carrying a load.

And more recently?

I think there was a real revolution afterthese early steps. These first peopleessentially sowed the seeds of biome-chanics. The progressive developmentof conventional radiography, CT andMRI certainly contributed to the deve-lopment of biomechanics. Computers,by allowing digital simulation greatlyenhanced these measurement modali-

ties and gave rise to biomechanics aswe know today.

Does this meanthat technical progressled to progress in the fieldof biomechanics?

Yes. If we look at electronic orthoticsystems, for example, we realise thatthey allowed the quantitative analysisof gait. Marey only performed a quali-tative analysis of gait. When we look atMarey’s images we clearly see theconcepts, but when we use electronicorthotics, we are able better describeand quantify the movement.

Apart from bioenginners,have specialists from otherdisciplines contributed to thisdeveloping science?

Clinical correlation of biomechanicaltheory has been absolutely vital. Forexample, orthopaedic surgeons havemade major contributions to the fieldof articular biomechanics.

We must not forget that Maquet andPauwels were orthopaedic surgeons.Vascular surgeons also helped bioen-ginners to understand circulatory phe-nomena and create models.Physiologists, scientists specializing inthe analysis and control of movement,tended to work with physiatrists, func-tional rehabilitation specialists.

Can we conclude that there hasalways been a link between bio-mechanics and clinical practice?

Yes, although this link varies accordingto the discipline. I think it is very closein orthopaedics, but not quite as closein the physiology.


ste : what is biomechanics?

PART


What is the reason forthis difference?

Orthopaedic surgeons are, by nature,closer to bioenginners, as they treatproblems “with their hands”. Their sur-gical procedures are very mechanical:they drill, screw, and ream. They worklike a mechanic on a machine, but ins-tead of working on an inert part, theyoperate on the human body. Drilling ahole in the wall to make a shelf anddrilling a hole in the tibia to insert aplate are very concrete procedures.This is not very different from a mecha-nic’s work in the industrial context.Orthopaedic surgeons have veryconcrete and pragmatic mentalities.

A history ofBiomechanicsin France

How long have you beendirector of the LBM?

I helped found the LBM and havebeen the director since it was first crea-ted. I was director of the ENSAMmaterials resistance laboratory in 1969,and then I was director of the structu-ral mechanics laboratory, where I star-ted to work on biomechanics. TheLBM was formed in 1979. Our firstbiomechanical work dates back to1972, at the request of Raymond Roy-Camille (inventor of the pedicularscrew). One of his students, GérardSaillant, who is now head of theDepartment of Orthopaedics and Deanat La Pitié-Salpêtrière, came to see me.He wanted to know whether I couldconduct mechanical trials on the ver-tebrae in order to identify the mostresistant region. In 1972, we therefore

studied the behaviour of vertebrae sub-mitted to mechanical loads inducingrupture and found that the pedicle wasthe region most resistant to rupture.Raymond Roy-Camille then asked usto study pedicular screw pull-outforces. Simultaneously until 1980, weconducted experimental studies withGérard Saillant at the Fer à Moulinexperimental surgery unit (the Pitié-Salpêtrière dissection unit whereorthopaedic and other surgeons areable to dissect bodies donated toscience). In 1976, we published anarticle on disk and nucleus pulposusimplants.

In a way, this represented thebirth of biomechanics in France.At the time, the teams led by JoannèsDimnet were working on analysis ofmovement in collaboration with Lyonhospital departments. I think thatDimnet had started several years pre-viously in the field of movement ana-lysis and then became interested in thevertebral column. In fact, the two of us

followed fairly parallel courses. Wetrained in the same institution, whichexplains why we had many points incommon and approached problemsfrom the same perspective. JoannèsDimnet was probably one of the firstpeople to have conducted biomecha-nical studies in France.

How did LBM start to grow?

The development of the LBM occur-red in parallel with a postgraduate trai-ning program, corresponding to aDiplôme d’Études Approfondies(DEA) (Postgraduate Diploma) inBiomechanics, accredited by universityauthorities in 1985. It was an option ofone of the specialties of the DEA inBiological and Medical Engineering ofthe Ile-de-France region. We enteredthis training program in 1987, to set upthe biomechanics option and the LBMreally started to take off at this time. AsI already mentioned, it started to takeshape in 1979, but really developed in1985. We took another big step forward


The 2TM experimental apparatus (2micrometric heads) allows experimental study of the behavior

of healthy, damaged and reconstructed vertebral segments.


when Wafa Skalli joined us. We wouldnot be as large as we are today if itwasn’t for her. She wrote a PhD thesison finite element modelling of the ver-tebral column. This was one of the firstvirtual representations of the vertebralcolumn and quite rare in 1983. Shethen joined our laboratory in 1988 andgreatly contributed to the growth ofdigital simulation.

▲ Finite element model of a L3-L4 segment

instrumented with a disc prosthesis

▼ 3D FEA modeling of a knee prosthesis

Was this the beginning of a newgeneration of bioenginneers?

Yes absolutely. The development ofdigital simulation allowed us toimprove our relations with surgeons,since it propelled our work beyond thelimits of strictly experimental research.Clinicians work experimentally with

their hands and we were able to contri-bute the digital elements of simulation.Virtual representation of the humanbody was an innovation at that time.

Could you explain how youbecame interested in biomecha-nics with your background ofconventional mechanics?

My basic training is in mechanicalengineering. I was trained at ENS(École Normale Supérieure) inCachan. I subsequently acquired tea-ching and research experience asdirector of the materials resistance ana-lysis laboratory. I then became directorof the structural mechanics laboratory(a structure is a system of mechanicalcomponents). Raymond Roy-Camille’srequest was very much in line with ourwork of mechanical characterization ofmaterials. There is not a major diffe-rence between characterizing ruptureof a vertebra and characterizing abeam in civil engineering, apart fromthe nature of the material. Changingfrom structural mechanics to osteoarti-cular mechanics therefore does notreally constitute a change of scientificdirection, but represents a continuousprocess. We subsequently developedmuch more specialized activities, moreclosely related to the human body. Thisspecialization on the vertebral columndeveloped very gradually, but in thebeginning, it was not a change of direc-tion, but simply a natural evolution. Wealso used the same approaches to ana-lyse these problems. We now havemachines which are very specific, but,in 1972, we broke our first vertebrawith devices designed to break metal-lic structures, because we did not haveany material specifically adapted to thehuman body.

Have you ever sufferedfrom prejudice on the partof surgeons?

No, I have encountered more prejudicefrom mechanical engineers. In thebeginning, when we were working onanatomic specimens, it induced morethan a scientific curiosity among my col-leagues. Some of our colleagues had avery negative view of our activities, as itwas based on dissection of cadavers. Wealso developed models using human tis-sues in order to conduct mechanicalexperiments. We had to crush these ver-tebrae. The negative perception of ourwork almost led to suspension of ourresearch. Nobody could criticise wor-king with a concrete or metal test tube,as they are inert parts, but handling acomponent of the human body in aschool of engineering was abnormal!

Do you think that these reactionswere culturally based?

Yes, absolutely. It was perfectly accep-table to examine cadavers in a dissec-ting room, but there was somethingstrange about studying components ofthe human body on mechanical testmachines. There was something notquite right. All of a sudden we wereusing machines designed to study inertmaterials in order to test componentsof the human body. This seemed verybizarre and unhealthy.

Experimental in-vitro study of the human pelvis

submitted to static lateral loads.


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Is this research now fullyaccepted?

Yes, but we founded a laboratory spe-cifically devoted to this field and wenow work in a site dedicated to thisactivity. We resolved the problem bycreating the biomechanics laboratory.Our work was difficult to accept whilewe were installed in a conventionalmechanics laboratory, but now thiswork is recognized as scientificresearch, as it is a CNRS laboratory(Centre National pour la RechercheScientifique) [French National Centrefor Scientific Research] and the contro-versy has been resolved. This wasnever a problem in North America.This laboratory therefore developedcontinuously and I gradually movedfrom the field of mechanics of struc-tures to mechanics of the human body.All of the specificities of the humanbody were gradually introduced, lea-ding to the development of our varioussubspecialities.

You mentioned the United States.How does the LBM compare withits American counterparts?

The field of biomechanics developedalmost simultaneously, but Europe pro-bably had a head start, because I don’tthink that Pauwels had an Americanhomologue. In fact, the first Americanstudies were conducted in the 1960s,and then rapidly developed between1970 and 1980, while the rapid growthof biomechanics in Europe occurredbetween 1980 and 1990.

Didn’t it occur somewhat later?

Let’s say that this discipline developedduring these years and was graduallyrecognized as a science. In France, theSociété de Biomécanique was foundedin the 1970s (François Lavaste was pre-sident of this association), but thissociety was founded by physiologistsand not mechanical engineers, who

joined the society a little later.

The Société de Biomécanique played areal federating role in the history of thisdiscipline, at least in France, andhelped to constitute it as a scientificentity. Its annual congress is nowattended by about 200 people, whichhas helped to forge the identity of itsvarious members. Within this Societywe know that we are all bioengineers:fluid bioengineers, osteoarticularbioengineers and physiology of move-ment specialists.

Study of the mechanical behavior

of a human knee.

Was this the birth of a networkbetween the various specialties?

A real network was developed, inwhich each person found his or herplace. As President of this society, oneof my concerns was to recognize theactivities of each of the members. Wetherefore established a file in whicheach member indicated his or herfields of interest. We found that onescientist tended to work in the field ofmuscles, while another worked in thevascular field and another worked inthe field of sport and movement. Thisgave us a clearer vision of biomecha-nics in France.

You mentioned that the LBMwas created to meet the needsof orthopaedic surgeons.

Did its creation coincide with thegrowth of biomechanics?

The creation of the LBM actually coin-cided with progress in orthopaedic sur-gery. Orthopaedic surgeons went loo-king for mechanical engineers becausethey felt that they had something tooffer them. To clearly understand thisprogress, it must be remembered that,before this time, surgeons designedorthopaedic products purely intuitively.They tried to communicate their ideasto a manufacturer who then developedan industrial product, but the wholeprocess was based on intuition!

Wasn’t this an empiricalapproach?

Yes, very much so, and the result couldonly be assessed after the implant hadbeen installed in the patient. When theclinician worked in collaboration withthe mechanical engineer, he was able toadd objective elements to his intuition.The birth of biomechanics thereforereflected this process and this reallycorresponds to the work of Pauwels. Hereplaced the purely intuitive process byan objective rational approach based onhis knowledge of engineering. This ledother surgeons to recognize the impor-tance of working with mechanical engi-neers in order to design their products.Raymond Roy-Camille, who intuitivelythought of stabilizing the vertebralcolumn by fixation of the pedicles, deci-ded to collaborate with mechanicalengineers. He wanted to make sure thathis idea was well founded, which is whyhe asked us to verify that the pedicleswere the most resistant part of the ver-tebra. Then, when he asked us to studyscrew pull-out, he wanted to knowwhether it would be better to anchorthe screws in the cortex of the pediclesand whether this was the site of bestpurchase. This was an opportunity formechanical engineers to observe enor-mous differences and variations fromone tissue to another. In some verte-brae, the screws could be pulled out byhand as the tissue was completelydegenerated, while in other vertebrae,forces of the order of 200 N had to beapplied.



Brief review of thehistory of the LBM.

1964 Pr Raymond Roy-Camille invented and usedthe first pedicular screw in surgery and establishedhis relationship with the LBM.

1972 First biomechanical studies in collaborationwith Pr Raymond Roy-Camille and Dr GérardSaillant on the mechanical behaviour of lumbarvertebrae.

1985 The LBM participates in the DEA (specia-list diploma) on Biological and Medical Engineeringfor the Ile-de-France region. Together with theorthopaedics department of La Pitié-Salpêtrièrehospital, LBM is responsible for the biomechanicsoption of this DEA. The ENSAM (École NationaleSupérieure d’Arts & Métiers) is accredited to deli-ver this DEA in coordination with the Universitiesof Paris XII and Paris XIII.

1988 Important growth of the LBM from this dateon, with a rapid increase in the number of PhD.s(six to eight new PhD.s per year) and extension ofindustrial partnerships. The LBM is transferred tonew premises. Close scientific cooperation develo-ped between Dr J. Dubousset (St Vincent de PaulHospital), Dr G. Duval-Beaupère (INSERM unit215) and the LBM.

1992 Setting up of international cooperation inthe field of spinal biomechanics with the Universityof Vermont in Burlington, USA (Pr Ian Stokes) andthe Ecole Polytechnique in Montréal, Canada (Pr J.Dansereau, Pr J. De Guise, Pr H. Labelle).

1993 The Board of Directors of the Société deBiomécanique appoints the director of the LBM asPresident of the Société de Biomécanique for a per-iod of two years, thereby acknowledging the scienti-fic work accomplished by the LBM in the field ofbiomechanics.

1996 The LBM is recognized by the CNRS as anEP 122 applicant team. In the context of spinal bio-mechanics research, and particularly the biomecha-nics of scoliosis, Professor Jean Dubousset joinedthe LBM team, thereby reinforcing the develop-ment of in vivo research.

Did this meeting give you a broader visionof biomechanics?

It showed us that biomechanics was not exclusively limi-ted to questions of resistance of materials, but that otherparameters were also involved, especially the variabilityof mechanical characteristics, related to age and tissuedegeneration. Parameters that we were not used totaking into account in our classical mechanical calcula-tions

Were the two disciplines enriched by thisexchange?

They both obtained an enormous and even fascinatingenrichment. By incorporating alloys, and by slightly modi-fying them, we can alter the mechanical characteristics ofsteel, but not to the same extent as those of bone tissue. Itwas at this point that we realised that biomechanics was notexactly the same thing as mechanics, as all of the parame-ters are radically transformed by the fact that we are dea-ling with living matter and not inert matter. ■ CS. Parent

[The second part of this interview will be published in thenext issue of ARGOS SpineNews]

Contact information

If you would like additional information or if you wouldlike to visit the LBM-ENSAM laboratory, please call:+33 (0) 1 44 24 63 24, or explore our website:www.paris.ensam.fr/web/lbm

or contact:Pr François Lavate - [email protected]

Pr Wafa Skalli - [email protected]

Research office:Laboratoire de biomécaniqueÉcole Nationale Supérieure d’Arts & Métiers151, boulevard de l’hôpital75013 Paris FRANCEPhone: +33 (0) 1 44 24 63 64Fax: +33 (0) 1 44 24 63 66Secretary: Vanessa Valminos


The first meeting of theArgentinean ARGOS

association was held in BuenosAires on August 10-12, 2000.

JEAN-PIERRE FARCY, MD ofNew York University’s Hospital for

Joint Disease and MaimonidesMedical Center was the guest speaker.Dr. Farcy is an internationally recogni-zed expert on the treatment of pedia-tric and adult deformity.

The conference’s first day was devotedto lumbar osteotomy for the correctionof post-fusion flatback deformity. Thehighlight of the day was a live surgicaldemonstration by Dr Farcy andDr Carlos Solá from the HospitalItaliano. This was followed by a livelygroup discussion of the indications for,

techniques of, and complications asso-ciated with these difficult procedures.

The second day was devoted to clinicalcase presentations. Diverse opinionswere discussed in a spirit of open-min-ded collegiality. As is common at scien-tific conferences, a general consensuswas obtained but unanimity of opinionwas impossible to find.

The international ARGOS frameworkhas provided an invaluable templatefor the growth of this fledgling researchgroup. We understand that Belgiumhas also formed a national ARGOSchapter and that discussions are pro-gressing toward an American organi-zation as well. The long-overdue goalof a worldwide community of surgeonsand researchers - enriched by local

experience but not bound by regionalprejudice - is becoming an exciting rea-lity. Lastly, we would like to convey ourappreciation to Euromed for theirgenerous support of our inauguralscientific meeting.

Left to right : Mr C. Carballo, Pr JP. Farcy,

Mr H. Segura


Inaugural meeting

of Argos - Argentina

communicationEvents

communicationEvents

A major event for all healthcare professionals was heldMarch 14-17 at the Parc desExpositions de Paris Nord.

THIS YEAR, the Hôpital expo andIntermedica trade shows merged

to form a single show and another fourexhibitions were added to this event:the salon du laboratoire-Bioexpo (themost important French life sciencestrade show), Stramed (the biomedicalindustry subcontractors trade show)and Hyprotex (textile hygiene andprocessing). These six shows nowconstitute the largest health care tradeshow in France.

More than 1.000 exhibitors presenteda panorama of their products and mostrecent equipment at this show, rangingfrom ancillary instruments to completeoperating rooms. Entire syntheticspines were even available. The largercompanies invested impressiveresources in this show, extending overan area of 70.000 m2. Each stand rival-led the others to catch the visitor’s eye.After visiting a waterfall, a theatrestage, and a sportsman in the middle ofa training session, the visitor could stopand watch an amazing presentation ofthe latest developments in robotics,supported by video interviews withsurgeons. A large number of visitorswere interested in textile processingsystems and restoration devices. A sec-tion was devoted to emergency andtrauma medicine, allowing the visitorto examine this equipment in detail.New technologies were strongly repre-sented. Many companies presentedtheir products in medical imaging andtelemedicine augmented by the limit-less possibilities offered by computers.

Another area of the show was devotedto the Internet. A Quebec delegationalso attended the show.

The Association Quebecois desFabricants de Matériel Médical(AQFIM - Quebec Association ofMedical Equipment Manufacturers)came to France to present its members’latest inventions. Thanks to new tech-nologies, we were able to participate ina paediatric cardiology examinationlive from Quebec. Mr JacquesDe Guise, associate Pr of the depart-ment of surgery at the faculty of medi-cine of the university of Montreal andPr in the department of automated pro-duction engineering in the Laboratoired’Imagerie, de Vision et d’IntelligenceArtificielle (LIVIA - Imaging, Vision

and Artificial Intelligence Laboratory)and Mr L’Hocine Yahia, full Professor,director of the biomechanics and bio-materials research group, mechanicalengineering department of the écolepolytechnique of Montréal presentedthe work of the Laboratoire derecherche en Imagerie et Orthopédie(LIO - Imaging and OrthopaedicsResearch Laboratory). ■ CS. Parent


Expo-Intermedica

THE PURPOSE OF THIS SEMINAR was to pre-sent new surgical procedures for the treatment of

spinal diseases, an overview of minimal invasive tech-niques in spinal surgery, and current theories in bio-mechanics. Scientists from “Maurice E. Müller”Institute for Biomechanics at the University of Bern,Switzerland, and from the Biomechanics Laboratoryof ENSAM (Ecole Nationale Supérieure des Arts &Métiers) in Paris, France, were present among surgeons fromdifferent countries. Pr Sapkas, who organised this congressin conjunction with the scientific committee (P. Efstasthiou,N. Zervakis, M. Kasseta, K. Kateros, G. Kountis, A. Badekas,N. Bitouni, P. Boscainos, E. Stilianessi, G. Tzagarakis, and V.Tzortzakis) gave all those in attendance the warmest welcomein the library of the little port of Poros, located at 50 mn fromAthens by boat. This seminar, which began on Friday June 9th inthe afternoon, and ended on Sunday, June 11th at Noon, was a perfect blend ofhigh level scientific exchanges, and conviviality. More information on this seminarcan be obtained from Pr George Sapkas ([email protected]) ■

7TH seminar of spinal

biomechanics, Poros Greece

www.aaos.org

This is the website of a famousAmerican Association: the AAOS(American Academy of OrthopedicSurgeons).

Unlike the Video Medical Journalwebsite, the colored interface of thehomepage encourages draws the visi-tor into the site. A great deal of infor-mation is available (ranging from publi-cations to CD-ROMs to videos).Nothing has been overlooked. Oneheading is devoted entirely to patientcommentary. Unfortunately, most ofthe site is exclusively reserved formembers of the Academy. The shearvolume of information may be overw-helming to inexperienced netsurfers,however.

www.ortho-link.com

The internet is not just a passing craze,it is everywhere. Today, no company orassociation can afford to ignore thismedia. Convinced of the importance ofInternet, our American partner,Ortholink, has taken up the challengeand developed a simple and effectivewebsite.

The first advantage of this site is thatthe designers have wisely avoidedsubmerging the visitor under tons ofsuperfluous information. The easy-to-read home page further facilitates theuse of this site. In contrast to the aus-terity of so many other websites, themodern design gives it an attractiveappearance and even inexperiencednetsurfers can easily find their way

around with, as bookmarks present atthe top and bottom of each page guidethe novice.

No matter how attractive the site, itonly has any real value when it pro-vides services not available withconventional media. The products mar-keted by Ortholink are described indetail. If you are interested in one ofthese products and wish to purchase it,remember that the on-line order formis protected by a security payment sys-tem.

www.paris.ensam.fr/web/lbm

We obviously could not devote anarticle to the Laboratoire deBioMécanique without presenting itswebsite, which is much more than asimple eMail address and provides awealth of information. It is not desi-gned to present scientific informationfor the general public, but it is never-theless accessible to non-specialists.

The general presentation is a relevantintroduction to the world of biome-chanics, all to brief, unfortunately.However, the four research groupscomposing the laboratory present theirwork in much more detail. You canread about the various studies, espe-cially those devoted to the spine. Don’tskip the other research groups, becausetheir work is sometimes presentedthrough animated sequences. Thepublications and communications hea-


Web reviewOrthopedic surgery appears on the internet in a variety of contexts ranging from academic institutionalwebsites and websites for commercial ventures to personal webpages for individual surgeons. Educationalmaterial and product information is now avalaible around the clock.

internetWeb review

internetWeb review

ding are particularly interesting. Aboutthirty doctoral theses are summarizedby abstracts, sometimes accompaniedby surprising illustrations.

Finally, the bilingual interface (French-English) is clear and practical.

www.expo-marey.com

If you missed the exhibition entitledÉtienne Jules Marey: le mouvementdes lumières, organized by theFondation Electricité de France from13 January to 19 March 2000, then thissite admirably attempts to summarizethe exhibition and provide even moreinformation about this extraordinaryman.

You will discover or rediscover therange of Marey’s inventions, each onemore fascinating than the next, fromthe cardiograph to the aeroplane aswell as biomechanical processes.

Two types of tours are available: the on-line exhibition and/or a thematic visit.We heartily recommend both of thesevisits, as they are very complementary.As you will see, the general presenta-tion of the site is very attractive andwell adapted to the subject treated.

There is only one drawback: there areonly a few video illustration (of allthings !), which are time-consuming todownload.

www.medecine-tv.com

General public television is alreadyavailable by Internet, but Progress-TVhas recently launched the first French-speaking channel entirely devoted tomedicine. Some sites already presentmedical information for the generalpublic, but medecine-tv is more parti-cularly designed for health care pro-fessionals.

You rapidly reach an attractive home-page, which is clear and easy to use. Alarge number of headings are presen-ted. We must congratulate the desi-gners, who have succeeded in combi-ning a user-friendly presentation witha large volume of information.

Take a look at the magazines with inter-views, or the various subjects devotedto surgery, etc. This last heading is par-ticularly interesting. The main advan-tage of this site is to exploit the variouspossibilities available by Internet, pro-viding on-line films devoted to thevarious medical specialties. A filmabout fifteen minutes long is devoted tospondylolisthesis. This film format isobviously not up to current standardsand the quality of the images largelydepends on your modem and phonecable. You must also have installed RealPlayer® software (free and easily down-loaded).

This interesting initiative neverthelessdeserves your attention.

www.orthopod.demon.co.uk

If you are looking for a video documentand don’t know how to obtain it,consult the British Video MedicalJournal website.

This site combines the two extensivevideo libraries of the BritishOrthopaedic Association and theAmerican Academy of OrthopedicSurgeons. Almost 200 videos on sub-jects as varied as the knee, the handsand the spine, are available.

It is true that the interface is fairly aus-tere and downloads are sometimes a bitslow, but you will be able to easily findyour way around this very accessiblesite. However, if you happen to find theobject of your desires, you cannotorder it on-line. Instead you will needto print an order form, fill it in andreturn it. ■ CS. Parent

… And don’t forget to consultthe ARGOS website:www.argos-europe.com


5TH InternationaArgos symFRIDAY JANUARY 26TH 2001, PARIS - MAISON DES AR

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A spine Obviously, we could not keep from alludingto Stanley Kubrick’s film. The beginning of the3rd millenium is the start of a new Odyssey forvertebral column surgeons. New technologiesare playing a greater role in daily surgical prac-tice. It seems only logical to dedicate this year’sARGOS symposium to this evolving interface.

The hardest part of designing the programwas deciding what to discuss and what toleave out. Thus, instead of discussing proventechniques such as video-assisted surgery, wehave chosen to concentrate on more eminentlyemerging - and perhaps not-yet-proven - techno-logies. The morning session will be devoted toimaging developments. We will be joined byengineers from General Electric, ProfessorChristopher Ullrich (neuroradiologist at theMedical University of South Carolina andPresident of the Cervical Spine Research

Argos Secretary : Marjorie SALÉ - Phone +33 (0) 3 21 21 59 64 - Fax +33

lmposium

RTS & MÉTIERS - 9BIS AV. D’IENA PARIS XVI

odysseySociety), Professor Jacques De Guise (fromMontreal’s Imaging and Orthopaedics ResearchLaboratory), and Professor Jean-Claude Doschof Strasbourg. Afterwards, we will discussprogress in intraoperative navigation systems.While these devices are intellectually enticing ,they have not yet proven their worth in dailysurgery. The Medtronic and Aesculap companieswill present their different processes.

In addition, they have agreed to allow twomembers of ARGOS use of their navigationsystems in the operating room. These experi-menters will tell us about their experience asnovices with these ultra sophisticated systems.We will have the opportunity to see the poten-tial, and potential limitations, of these technolo-gies by viewing a live surgery from the opera-ting theater at the IMM. In the afternoonsession, we will examine the legal pitfalls for

insuring data security that are incumbent in thistechnology. Cegetel, the company whodesigned and oversees the French health carecomputer network, will share their experienceswith us. The day will conclude with aninvestigation of the rapidly multiplying Internetsites created by orthopaedic surgeons.Professor Jean-Pierre Farcy will discuss thepossibilities and restrictions on these sites andMme. Isabelle Lucas Balloup, attorney “à la courde Paris” will temper our enthusiasm byreviewing the many European statutesgoverning this new realm of discourse.

Sadly, we realize that the day will be too shortto examine fully all aspects of this technologicaland surgical revolution. We hope instead to illu-minate this new world, spark a collegial debateabout its evolving role, and begin a dialogue onthe very future of medicine.

The Argos Board: Christian Mazel MD,Pierre Kehr MD, Jean-Paul Steib MD,Alain Graftiaux MD, Frank Gosset MD.

(0) 3 21 21 59 70 - [email protected]

Iron atoms in a copper matrix.

Many Arts et Métiersengineers and future engineers

accepted this invitation toparticipate in a conference-

debate on nanotechnologies atthe Ecole Nationale Supérieure

d’Arts et Métiers in Paris, onWednesday 15 March 2000.

André MASSON, FormerPresident of Angénieux SA and

Founding President of thenanotechnology club,

presented a convincing paperon this infinitely small universe

with the participation of JeanFOURMENTIN-GUILBERT,

President of theFOURMENTIN-GUILBERT

scientific foundation for thegrowth of biology.

NA N O T E C H N O L O G I E Sconcern the materials, methods

and processes used to observe andmanufacture products or structureswhose dimensions or acceptableranges are of the order of nanometres

(10-9m), in other words a sizecomparable to that of the basiccomponents of matter (atoms andmolecules). They cover the range ofdimensions from 0.1 to 100nanometres. Take a millimetre (10-3m),divide it by 1000 and you obtain amicron (10-6m); divide a micron by1000 and you obtain a nanometre.

Nanotechnologies have given birth tonanosciences: these “new frontiers ofthe technologically possible”. Forexample, they are designed to displace,manipulate and even assemble atoms.We often use these technologies in eve-ryday life, often without being aware ofit. For example, to ensure correct rea-ding of a compact disc, the drive shaftmust be stable to within 20 to 30 nano-metres. General public printers are fit-ted with inkjet print heads, which weredeveloped by means of processes witha similar degree of precision.

The prospects for the future are veryattractive, as these disciplines aregoing to become an integral part ofcomputers, medicine, biology, surgery,etc. Ultraprecision machining willallow even greater miniaturization andcompactness, thereby increasing thefunctional capacity of products. Onepossible application would be implan-table drug delivery systems. It wouldeven be possible to introducetransducers and detectorsinside an artery! However, thecomplexity and volumes thatcan be achieved at the pre-sent time are still very insuf-ficient.

Other potential applications arealso very interesting. If scientists couldmanipulate atoms one by one, it would

be possible to eliminate all impuritiesfrom matter and create more resistantproducts. For example, glass has beenmade from silica, but without involvinga fusion step. This experience showedthat the physical properties of the glassobtained were radically altered. Evenmore astounding discoveries can beexpected with very light materials, butjust as resistant as diamonds.

André Masson and Jean Fourmentin-Guilbert emphasized the importance ofnanotechnologies in tomorrow’s world.They announced that the President ofthe United States, Bill Clinton, has pro-posed that the budget of 200 milliondollars already devoted to these tech-nologies be doubled. In Japan, a sum of500 million dollars is devoted to thisresearch! ■ CS. Parent

A synthetic self-assembling spherical complex.

Cover caption “Tetramethyladamantane”

(green) is encapsulated by two molecules of a

self-complementary synthetic receptor. An

array of weak intermolecular forces are balan-

ced to produce the assembly in solution. (Red

spheres, oxygen atoms, blue spheres, nitrogen

atoms.)


Discover the fantasticworld of nanotechnologiesand its expected growth at the beginningof this new millenium

scienceNanotechnologies

A “Buckyball”

Considerable progress hasbeen made in the field of

spinal surgery in recent years,and instrumentation as well as

the basic principles ofcorrection have been enrichedby new ideas (6). Despite this

extraordinary progress, themodes of vertebral fixationremain limited to pedicular

screws, and laminar orpedicular hooks (8), or

sublaminar wires or cables.Each type of implant has its

own supporters and detractorsand each one has its respectiveadvantages and disadvantages.

ALL OF THE CURRENTLY avai-lable implants are unilateral and

only fix the left or right part of thespine. The Raymond Roy-Camillepedicular screw is now 35 years old(11) and is very technically demandingto insert. Although it ensures solid fixa-tion of the posterior and anterior partsof the vertebra, there is always a risk ofpedicular perforation, especially in thethoracic spine (4). Laminar hooksrequire opening of the vertebral canal;they have an upward or downwarddirection of fixation, requiring a dis-traction or compression force, whichcan be neutralized by a posterior lami-nar (12) or pediculo-transverse clamp.Wires require repeated opening of thecanal with simple, but not very solidfixation and do not allows distraction orcompression efforts.

These various aspects led to the idea ofdevelopment of a new form of fixation,which is easy-to-insert without ope-ning the canal, solid with bilateralanchoring and without prestressingduring insertion, and allows distrac-tion-compression and anteroposteriortraction or pushing forces.

Material:

Since the costover-tebral space is avirtual space andis frequentlyused to inserttransverse processhooks and to per-form pediculo-trans-verse clamps, it should besuitable for use in this set-ting (fig. 1). After removal ofthe tip of the transverse pro-cess, the pedicle can be reachedby passing between the rib and the ver-tebra. Two bifid plate hooks are placedin contact with the lateral surfaces ofthe pedicles, while the body of thehooks rests on the base of the trans-verse process.

A transverse com-pression link connects

the two implants andencircles the posterior

laminar arch. This consti-tutes a lateral clamp, whichgrasps the vertebra by its

two pedicles (fig. 2a,2b,2c).The body of the hook is at an

angle of 90° to the axis of the plate inorder to receive a rod from each side.The bipedicular implant (BPI) there-fore constitutes a new method of fixa-tion, with novel anatomic relations andlateral purchase. The safety and relia-bility of this bipedicular vertebral fixa-tion had to be evaluated.


evaluationA new bipedicular implant

fig. 1

Costo-vertebral space

=

safety zone

fig. 2a

A new bipedicular implantAnalysis of a new spinal fixation device

Jean-Paul STEIB, MD,* Emeric GALLARD, MSc Eng,** Laurent BALABAUD, MD* ■

fig. 2c

fig. 2b

* Hôpitaux Universitaires de Strasbourg - ** ENSAM Biomechanics Laboratory


Methods:

A biomechanical evaluation was necessary to validate thisnew fixation (3, 9). Studies are currently underway onfresh cadavers in the ENSAM Laboratoire deBiomécanique (LBM) [Biomechanics Laboratory] inParis (7). These studies are designed to assess solidity andstability (1, 10, 14). Solidity tests initially consist of eva-luating the resistance of the pedicles to bilateral com-pression forces (fig. 3). This pedicular resistance is fun-damental to assess the safety of the implant, as excessivefragility could threaten the spinal cord. The posterior andlateral pull-out forces (2, 5) of the bipedicular implantfixed onto an isolated vertebra are then evaluated (fig. 4).

Stability studies are designed to evaluate the mobility ofthe instrumented thoracic spine using two CD instru-ments, one using standard pedicular hooks, and the otherthe bipedicular implant (fig. 5).

In both types of fixation, T11 is fixed onto a platform andT3 is subjected to various loading modes: flexion-exten-sion, lateral inclination and axial rotation.

Displacements of the T3, T6, T7 and T8 vertebrae aremeasured for each loading and the curves correspondingto the two types of fixation are compared.


fig. 3

Compression strength

References

1. Abumi K, Panjabi MM, Duranceau JBiomechanical evaluation of spinal fixation devices:

III. Stability provided by six spinal fixation devices

and interbody bone graft. Spine 1989; 14 (11): 1249-

1255.

2. Berlemann U, Cripton P, Rincon L, LippunerK, Schlapfer F - Pull-out strength of pedicle hooks

with fixation screws: influence of screws length and

angulation. Eur. Spine J. 1996; 5:71-73

3. Diop A, Skalli W, Lavaste F - Tests et épreuves

biomécaniques incontournables pour le développe-

ment d’une nouvelle instrumentation rachidienne. In:

Pous, Les instrumentations rachidiennes. Cahiers

d’enseignement de la SOFCOT, 1997: 31-40

4. Doursounian L, Henry P - Vissage pédiculaire.

In: Pous, Les instrumentations rachidiennes. Cahiers


5. Gayet LE, Muller A, Pries P, Duport G,Bertheau D, Lafarie MC - Etude de la résistance à

la traction de l’arc vertébral postérieur thoracique.

Rachis 1998 ; 10(1): 19-26

6. Karger G, Steib J.-P, Roussouly P, Chopin D,Roy C, Dimnet J, Mazel Ch, Marnay T, Dimeglio ALes “nouveaux” systèmes d’instrumentation rachi-

dienne postérieure. In: Pous, Les instrumentations

rachidiennes. Cahiers d’enseignement de la SOF-

COT, 1997: 121-128

7. Lavaste F - Biomécanique et ostéosynthèse du

rachis. Cahiers d’enseignement de la SOFCOT.

Conférences d’enseignement 1997: 121-145

8. Milon E - Crochets pédiculaires, laminaires et

transversaires. Du Harrington au Cotrel-Dubousset.

In: Pous, Les instrumentations rachidiennes. Cahiers


9. Panjabi MM - Biomechanical evaluation of spi-

nal fixation devices: I. A conceptual framework.

Spine 1988; 13 (10): 1129-1134.

fig. 4

Pull-out strength

lateral pull-out force

posterior pull-out force

F F


Traditional CD construct BPI constructfigure 5

Discussion:

This implant allows pedicular anchoring without openingthe canal and without destabilizing the spine. Sacrificeof the tip of the transverse process appears to have negli-gible consequences. This device can be safely implanted(13) in an avascular space devoid of any nervous struc-tures. Unlike pedicule screws, this technique is not asso-ciated with a difficult learning curve and the possibilityof accidental and unidentified perforation of the vertebralcanal with its potentially serious consequences. The BPIis not incompatible with laminectomy if the pedicles arepreserved and are in a good condition. There is no spe-cific direction of use (neutral implant), in contrast withthe currently available hooks. Its action and excellentpurchase are very useful for correction of deformities byrod rotation or in situ contouring. Spatial manipulationof the vertebrae should be facilitated, especially in thehorizontal plane, which should primarily allow effectivecorrection of rotation.


References

10. Panjabi MM, Abumi K, Duranceau J, Crisco JJBiomechanical evaluation of spinal fixation devices:

II. Stability provided by eight internal fixation

devices. Spine 1988; 13 (10): 1135-1140.

11. Roy-Camille R, Garcon P, Begue ThTechniques chirurgicales. Etude biomécanique de

l’ancrage des vis pédiculaires dorsales et lombaires.

7èmes journées de la Pitié-Salpétrières 1990: 29-35

12. Tencer AF, Self J, Allen BL, Drummond DDesign and evaluation of a posterior laminar clamp

spinal fixation system. Spine 1991; 16(8): 910-918

13. Thanapipatsiri S, Chan DPK - Safety of thora-

cic transverse process fixation: an anatomical study.

J. Spinal Dis. 1996 ; 9 (4):294-298

14. Wilke HJ, Wenger K, Claes L - Testing criteria

for spinal implants: recommendations for the stan-

dardization of in vitro stability testing of spinal

implants. Eur. Spine J. 1998; 7:148-154

T11

T7

T3

Z

X Y

Z

X Y

T11

T7

T3

fixation of T11

Application of loads

in the three planes

on T3

Measurement

of the relative 3D motions

between T6 and T8

Standardhooks

Standardhooks

Standardhooks

bipedicularimplant

bipedicularimplant

Standardhooks

Standardhooks

Cross link

Cross link

Conclusion:

This new type of implant needs to be tested in in vivo clinicalsituations, but the preliminary results are promising and suggesta multitude of applications, not only for fixation and correctionof vertebral deformities, but also for fixation of the traumatic,tumoral or degenerative spine. Improvements will be madedepending on the results of ongoing trials. ■

The year 2000 is the year ofnew technologies. The Internetis developing at an exponential

rate, and new technologies,only recently embryonic, areemerging nearly full-grown.

SURGICAL navigation or “stereo-taxis”, first developed in the 1980s,

in the field of neurosurgery, has nowbeen extended to other specialties,especially orthopaedic surgery. Sincethe end of the 1980s, pedicular align-ment systems for spinal surgery havebeen developed according tovarious principles, butalways with the sameo b j e c t i v e :spatial

guidance of a high-risk surgical procedure,

using medical imaging and 3D locali-zation systems, in order to avoiddamage to particularly fragile struc-tures such as nerve roots or dura mater.Then, in the 1990s, navigation systemswere developed in the field of kneesurgery and the objective, in thiscontext, was to improve the positioning

of femoral and tibial implants duringtotal knee arthroplasties. Other stereo-tactic applications in orthopaedic sur-gery, such as knee ligament recons-truction, or insertion of acetabularimplants, were also developed. Severalresearch centers all over the world arecurrently working in the field of com-puter-assisted orthopaedic surgery,including the Laboratoire d’Imagerieet Orthopédie (LIO) [Imaging andOrthopaedics Research Laboratory] inMontréal (Quebec), the TIM-C labo-ratory of Joseph Fourier University inGrenoble (France), and the UPMCShadyside Hospital Center forOrthopedic Research inP i t t s b u r g h ,Pennsylvania(USA).

A l t h o u g hthese technolo-

gies, grouped under the generic termof “surgical navigation”, are very useful

for orthopaedic surgeons wishing toensure a spatially safe and reliableprocedure, they do not provide

any information for the choice ofprocedure, and do not allow retros-

pective evaluation of the efficacy of theprocedure chosen. In addition, they arepurely intraoperative technologies andhave offered little advantage to the pre-and postoperative phases of patientcare.

In spinal surgery and knee surgery,medical images (x-rays, MRI, CT, etc.)are most of time used as qualitativesources of information, and very few

tools provide surgeons and radiologistswith rapid, reproducible and precisemeasurements of morphological andfunctional parameters. These measu-rements would have a three-fold value:to provide surgeons with quantitativeobjectives that can be used during theoperation (with orwithout surgicalnavigation), toverify theimme-diate

postopera-tive result obtained in terms of the

desired adjustments and to follow thecourse of morphological and functionalparameters over time in relation to theclinical results obtained.

Noninvasive measuring modules,based on analysis of standard medicalimaging and/or direct measurements,linked to a clinical database, wouldprovide orthopaedic surgeons with aglobal quantitative vision of theirpatient’s morphology, posture and jointmobility. This information, accessibleto a given surgeon for all of his patients,would enable the surgeon to gainmaximum benefit from his everydayexperience, and beyond that, to sharethis experience with his peers on thebasis of objective measurements.

The locomotor apparatus is particularlysuitable for this type of approach, as itis submitted to considerable cyclicalmechanical loads related to the


New trends in computer

technologiesComputer-assisted surgery

communicationComputer-assisted surgery

patient’s morphology and posture. The range and type ofjoint movements are also very important factors in bio-mechanical load distribution, and consequently in thepatient’s postoperative outcome. Measurement of thepostural and kinematics parameters of the locomotorapparatus therefore has an important place in the choiceof operative strategy and analysis of the postoperativecourse in orthopaedic surgery, but many sources of infor-mation, such as conventional radiography, are currentlynot used to their full advantage. ■ A. Templier

From leonardo Da Vinci sketches

to 3D medical imaging.


assisted surgery

Surgiview®:first surgeons,then tools…

THE SURGIVIEW® company was created in April2000 in order to develop a full range of computer-

assisted diagnostic, surgical and follow-up tools.Combining the needs and skills of orthopaedic spe-cialists, orthopaedic surgeons, and also biomechanicaland medical imaging scientists and industrial partners,SurgiView®, in the context of an Eureka project(∑ 2288 Medac), intends to provide surgeons, over thenext two years, with a complete range of software pro-ducts and equipment designed for preoperative andpostoperative assessment and navigation in ortho-paedic surgery. The current official partners of thisproject are:

- Laboratoire de Biomécanique de l’Ecole Nationale Supérieure

d’Arts & Métiers, Paris (France)

- Laboratoire d’Imagerie et d’Orthopédie, Montréal (Quebec)

- Association ARGOS (international Association of Research

Groups for spinal OsteoSynthesis), Paris (France)

- Zebris, Tübingen (Germany)

- IVS, Chemnitz (Germany)

- The Eurosurgical and Tornier companies.

The first module proposed by SurgiView®, composedof SpineView® 1.0 software and the clinical database,is currently under investigation in French clinical cen-ters participating in the project:

- Institut Mutualiste Montsouris – Paris (Dr Mazel),

- Hôpital Hôtel Dieu – Nantes (Prof. Passuti, Dr Delecrin),

- Hôpital Pitié – Paris (Prof. Saillant, Prof. Lazennec),

- Hôpital Beaujon – Paris (Prof. Guigui),

- Hôpital Tripode – Bordeaux (Prof. Vital).

A progress report of these studies will be presentedregularly in your ARGOS SpineNews journal.

Computer-assisted imaging of coronary arterial flow.

“The hope of reachingthe truth is sufficient for those

who pursue science throughall their efforts:

the contemplation of the lawsof nature has provided great

and noble enjoyment to thosewho have discovered them”.

Etienne-Jules Marey (1830-1904)

WHAT DO biomechanics, bird-watching and a good film have

in common? Nothing at first sight, butlet us look more closely at the work ofEtienne-Jules Marey.

Born in Beaune (France) in 1830(where a museum is devoted to his lifeand work), this Burgundian, from ahumble background, remains one ofthe major figures of 19th centuryscience. He was simultaneously a doc-tor, physiologist, clinical pathologist,professor at the College de France anda member of the French Academy ofMedicine. He was also responsible fora multitude of discoveries with appli-cations from medicine and physiologyto aviation, cinema and photography.

The majority of his career was devotedto the development of graphic methodsto record physiological activity. Heconducted some remarkable studies onblood circulation and cardiac mecha-nics, but his insatiable curiosity also ledhim to investigate many other areas oflocomotion from analysis of the flight ofbirds to a detailed description ofhuman gait. This movement-fascinatedscientist was largely forgotten after hisdeath but his legacy studies, drawings,graphs, photography, and films (the

first films in the history of cinema) haverecently begun to receive their long-overdue attention as scientific disco-veries and magnificent works of art.

At the end of the last century, thisFrench physician-physiologist was thefirst to analyse movement in detail aswell as measure it and rigorouslyreproduce it.

“This approach constitutes one of thefoundations of modern orthopaedics”according to another important figureof biomechanics, Johannes Dimnet,former director of the Laboratoire deBiomécanique du Mouvement(Biomechanics of MovementLaboratory) at Claude BernardUniversity in Lyon (France).

Photography played an essential role inMarey’s research. Using this process,he developed chronophotography in1892. With this process, biomechanicstook a giant step forward. His invention“the photograph gun” was able tobreak down any movement into itscomponents by successive views takenat regular intervals over time.

“The photograph gun”

By taking series of twelve images persecond, Marey was able to describe, forthe first time, the sequence of visiblemovements of a walking man, but his

process was unable to cross the barrierof the skin to observe joint movements. Many photographs were taken with analmost cubical box with sides measu-ring about thirty centimetres. Althoughdeveloped in 1890, they already dis-played all of the principles of thecamera, as subsequently defined by theLumière brothers. It included animpression frame and a spring motor.He also used celluloid films, whichstopped intermittently in front of thefocal point of the lens.

“The cubical box”

In 1961, the French Cinémathèqueacquired about 400 letters written byEtienne-Jules Marey between 1881and 1894 to his assistant Georges


Etienne-Jules

MareyThe eye of Biomechanics

historyEtienne-Jules Marey

historyEtienne-Jules Marey

Demeny (now recognized as the realinventor of cinema). This very valuablecorrespondence is stored in the FilmLibrary, and has been indexes with anumber of letters found in otherarchives. This collection also includesabout sixty unpublished letters fromthe period 1877-1904. In particular,this documentation provides a precisedescription of the scientific programmedeveloped by Marey and Demeny atthe Parc des Princes physiology station.It was in this now mythical place thatthe two scientists worked to developtheir various chronophotographicdevices. A window into the scientificworld at the end of the 19th century,this collection also reveals the privateside of Marey, especially theNeopolitan holidays he so enjoyed.

EJ. Marey working in his garden

As a pure scientist, Marey refused tomarket his process, which was rapidlytaken up by his contemporaries…Louis Lumière improved this appara-tus, then patented the process in1895. ■


THE PURPOSE of The International Society for the Study of the LumbarSpine, a non-profit organization founded in 1974, is to bring together

those individuals throughout the world, who, by their contributions and acti-vities both in the area of research and clinical study, have, or are indicatinginterest in the lumbar spine in health and in disease. Its further purpose isto serve as a forum for the exchange of information of both an investigativeand clinical nature which relates to low back pain and disability.

The International Society for the Study of the Lumbar Spine has establisheda Research Fellowship to promote and extend research activities into the causeand cure of low back pain. The fellowship is awarded annually based upon themerits of the applicant, as judged by the Fellowship Committee of the Society.Currently, a stipend of $15,000.00 US. will be granted to the recipient.

A prospective applicant should have completed formal training in a medicalor allied specialty and should be involved in an investigation of a specific pro-blem which would be furthered by travel to a location other than his own. Anapplicant should be sponsored by a member, or must be a member of TheInternational Society for the Study of the Lumbar Spine.

The competition is open to all qualified investigators who may apply singlyor as representative of a group. Application is to be made by a letter to aCommittee, specifying the details of the topic to be pursued, the location towhich the fellow would travel to further his study, and the expectations ari-sing from the venture. Along with the letter of application, a prospective fel-low should provide a Curriculum Vitae for each proposed investigator and astatement of sponsorship of the applicant from a member of the Society, aswell as a letter from the Institution the applicant intends to visit confirmingtheir acceptance of your visit. Also please include the Curriculum Vitae of theresearcher you will visit. Four copies of each should be submitted.

Applications for the 2001 competition must be received by March 1, 2001.The Committee will announce its selection shortly after this date. The reci-pient of this award should be prepared to present a report of his efforts to the2002 annual meeting in Cleveland, OH, USA, May 14-18th. ■

Applications should be submitted to The International Society for the Study of the Lumbar

Spine Sunnybrook and Women’s College Hospital Science Center - 2075 Bayview Avenue,

Room MG 323, Toronto, Canada, M4N 3M5

Phone 416-480-4833 - Fax 416-480-6055

eMail: [email protected]

Fencing motion analysis

Closing the loop in surgicalpractice: ssing computerassisted surgical tools to

enable continuous processimprovement in healthcare

The Centers for Medical Robotics andComputer Assisted Surgery (MRCAS)establish a collaboration between thesister labs at UPMC ShadysideHospital and Carnegie MellonUniversity’s Robotics Institute. TheMRCAS program is helping to takeorthopaedics and other surgical sub-specialties into the 21st century. Thisunique program combines robotics,engineering and computer science toassist physicians in the planning, simu-lation and performance of surgery aswell as in measurements of postopera-tive outcomes. The goal of the Centersis to foster the application of theseenabling technologies within all areasof medicine and surgery with the initialprimary focus in orthopaedics.

The success of the program is foundedon the tight integration in three mainareas: (I) clinical programs; (II)research and development into the

“surgical toolbox of the future” and thenext generation of more accurate andless invasive computer-based surgicaltools; and (III) developing metricsand measuring patient outcomesthrough a Total Joint Registry.

The MRCAS program relies on institu-tional and regional strengths in existingclinical programs and expertise in theareas of computer science, robotics andhealthcare and provides the focus ofactivity that integrates high quality cli-nical practice and the research anddevelopment of new innovative tech-nologies. These tools have the potentialto help our patients by making proce-dures less invasive and more accurateand also by directly relating patient out-comes to measurements of surgicaltechnique - in essence “closing theloop” in surgical practice. This com-

prehensive approach will improvepatient outcomes in a cost-effectivemanner by enabling continuous processimprovement, immediately and in thefuture.

What is Medical Robotics andComputer Assisted Surgery?

Medical robotics and computer assistedsurgical technologies span the broadareas of science and engineering tocreate intelligent tools that can beapplied to clinical practice. Robotictechnologies, navigation systems andcomputer assisted tools can improveexisting clinical procedures as well asprovide innovative new approaches toclinical problems. A new breed ofcomputer-based devices presents sur-


The center for medical

robotics and computer

assisted surgeryat UPMC Shadyside and Carnegie Mellon University

A. DiGioia, B. Jaramaz, T. Levison, J. Moody, C. Nikou, R. LaBarca, P. Muir & F. Picard ■

focus onThe Robotics Institute

fig. 1 - Hip replacement surgery using HipNav: Optical localizer tracks the position of bones and

tool. Information is displayed on the TV monitor.


geons with robust, clinically practicaltools that can do much to augment thephysician’s skill while reducing theexpense of healthcare. Moreover, thesetools can be used to directly relate mea-surable surgical practice to patients’outcomes enabling continuous processimprovement in healthcare-reducingcosts by ensuring quality.

In addition to the ongoing work withinthe Robotics Institute and UPMCShadyside, MRCAS draws upon addi-tional personnel and resources fromdepartments within Carnegie MellonUniversity such as Civil Engineering,Biomedical Engineering, andComputer Science. MRCAS has threeprimary goals:

1- perform application-orientedresearch aimed at addressing real lifeclinical needs.2 - promote collaboration betweenphysicians and researchers.3 - raise the awareness and supportfor robotics and computer assistedtechniques within medicine throughan active educational program.

Some of the technology already existsto address these clinical needs; howe-ver, the integration of the constitutiveparts is often lacking. The programbrings together the diverse areas thatare necessary to address these pro-blems.

One example and direct result of theinterdisciplinary collaboration fosteredby MRCAS is the unique image guidedsurgical navigation system called HipNav (for Hip Navigation System) thathas been developed to accurately mea-sure and guide alignment of implantsduring total hip replacement surgery.HipNav has three components. Thefirst component is a preoperative plan-ner and simulator in which the surgeoncan pick the appropriate implant sizeand optimal position of the femoral andacetabular components given thepatient’s specific anatomy. The secondcomponent is a range of motion simu-

lator that displays and animates therange of motion of the hip and impin-gement conditions for any position ofthe patient’s leg. The range of motionsimulator permits the surgeon to opti-mize the position of the implants inorder to reduce the chance of impin-gement and dislocation for any indivi-dual patient. (fig. 2)

fig. 2 - Surgical planner and Range of motion

simulator for total hip replacement: Limits of

leg motion are interactively animated for selec-

ted implants and leg motion paths.

The third component is an intraopera-tive navigational system then allowsthe surgeon to measure and accuratelyplace the implant in this “ideal” posi-tion. The expectation is that properimplant alignment will not only reducethe risk of dislocation, but will improveoverall hip mechanics and reduce thechance of longer term problems likethe generation of wear debris due toimpingement. In addition, these tech-nologies will permit the developmentof minimally invasive surgical tech-niques, which will improve the shortand long-term outcomes of our patients(fig. 1).

In April of 1997, we began a clinicaltrial using HipNav. The clinical infor-mation that we are collecting has beenvery enlightening and provided mea-surements which surgeons never hadavailable before. One of the mostimportant contributions of HipNavand other computer-assisted technolo-gies is providing surgeons and clinicalresearchers with an accurate intraope-rative measurement tool. For instance,with HipNav we can for the first timeintraoperatively track (in real time) the

movement of the patient’s bony ana-tomy during all phases of surgery.Furthermore, we can measure the finalposition of the implants. These measu-rements will permit us to directlyrelate surgical technique to patient out-comes. HipNav technology has alsoenabled the development of less inva-sive surgical techniques while impro-ving accuracy.

Our program is at the forefront of seve-ral other areas of active research anddevelopment that we expect to directlyimpact surgical practice in the nearfuture. We have developed, demonstra-ted and hope to soon clinically use animage overlay system which permits thedisplay of medical images on the patientduring surgery that in essence gives thesurgeon “x-ray vision” (fig. 3a, 3b).

fig. 3a: Image overlay visualization system-

giving the surgeon “X-ray vision”

fig. 3b - Image overlay system displays medical

images and preoperative plans overlaid on the

patient. In this case, the surgeon can “see

through” the patient permitting display of a

pelvic CT and planned acetabular implant

orientation.

We have also extended the enablingtechniques used in HipNav to surgicalnavigation around the knee. KneeNav



will be used clinically in the comingmonths to assist surgeons in perfor-ming total knee replacement (TKR)and anterior cruciate ligament recons-tructions (ACL).

We began a collaborative programwith Dr Freddie Fu (Chairman of theOrthopaedic Department at theUniversity of Pittsburgh) to develop anACL/PCL surgical navigation modulefor KneeNav. A randomized study onsawbones was already performed tocompare the accuracy of KneeNav witha traditional arthroscopic technique.KneeNav system improved reliabilityand repeatability of ACL reconstruc-tion. Surgical error was significantlyless important using the computerassisted system. About four computer-assisted procedures were sufficient forexperienced surgeons involved in theexperiment to become proficient withthe technique. This computer-assistedACL navigation system has the poten-tial to reduce surgical error and varia-tion from optimal graft alignment.Subsequent studies will focus onimproved models and clinical use as ameasurement tool first and then as acomplete navigation system.

fig. 4 - Sagittal cut plane of the virtual ACL.

In parallel, a KneeNav-TKR systembeing developed at UPMC ShadysideHospital. During alignment of the cut-ting jigs the surgeon views a videomonitor that displayed the currentposition of the traditional guides rela-tive to the femur and tibia. The sur-geon slides a pre-calibrated “plate-probe” tracker, into the usual saw slotof the mechanical guides. A video

monitor provides intra-operative mea-surements of alignment and guidanceinformation. Specific user interfacesrepresent predefined mechanical axes,which are the surgical frame of refe-rence and serve for cutting guideorientations.

The surgeons are then able to measuretheir surgical practice, and also ideallyorient the cutting guides relative to themechanical axes. Bone cuts are done inthe usual manner using an oscillatingsaw, and the surgeon can then check thecutting plane using the same plate-probe.

The implants are then secured, and thesurgeon verifies soft tissue balancingand alignment using specific interfacessimultaneously displaying relativebone movement. First experimentsproved feasibility, repeatability andreliability of this computer-assistedknee system. An IRB (InstitutionalReview Board) approval has beengranted and will allow us to assess thesystem in clinical trial. Several studiesare already scheduled to use KneeNavas a measurement tool or compare it toother current commercial product (asOrthopilot system).

fig. 5 - KneeNav-TKR. The TV monitor dis-

plays simultaneously bones, mechanical axes

overlaid and cut orientation.

We are also developing robotic mani-pulators and microelectromechanicalsystems (MEMS) which will embodythe next generation of surgical toolsand measurement devices. These toolswill eventually permit more accurateand less invasive surgical proceduresall to the benefit of our patients.

Measuring Patient Outcomes:

The Total Joint Registry Improvementsin current medical procedures requirethe evaluation of clinical results andpatient outcomes. The costs of newtechnologies must be weighed againstthe benefits, potential savings andimproved clinical outcomes, especiallyin today’s healthcare environment.The Total Joint Registry has developeda database to evaluate clinical andpatient-perceived outcomes followingtotal joint replacement surgery.

The Total Joint Registry includes ageneral clinical database to facilitatethe evaluation of joint reconstructionprocedures. Candidates for theRegistry include any patients under-going total hip or total knee replace-ment surgery. Patients are evaluatedpreoperatively, as well as postoperati-vely at 3 months, 6 months, 1 year andannually thereafter. The information iscollected prospectively and by an inde-pendent observer and includes theHarris Hip Score or Knee SocietyScore, the SF-36 Health Status Survey,and a Hip/Knee Outcomes DataCollection Instrument. In addition tothese clinical and patient reportedoutcome measures, the Registry datacan be used to track real costs (as oppo-sed to hospital charges) of total jointreplacement surgery, as well as costsassociated with the treatment of com-plications and required revision sur-gery.

The Total Joint Registry will provide apool of data for comparison and deter-mination of clinical outcomes from sur-geons’ and patients’ perspectives. Thisoutcomes information can also be usedto develop a mechanism to evaluatenew surgical interventions and tech-nologies in total hip and total kneearthroplasty, in terms of patient out-comes, surgical outcomes and costeffectiveness. The goal of the TotalJoint Registry and our clinical out-comes project is to develop a resource



upon which surgeons can draw to assistthem in the clinical decision makingprocess. This will promote increasedaccuracy and efficiency in orthopaedicpractice improving patient outcomesthrough continuous process improve-ment ensuring quality patient care.

To date, the Total Joint Registry hasenrolled over 330 patients. In addition,the Registry will be open to all patientsfrom interested orthopaedic surgeonsin the Pittsburgh area, thus increasingthe pool of patient information avai-lable for clinical research studies.Ultimately, this standardized outcomesdatabase will permit comparison ofpatient outcomes from multiple sur-geons and medical centers.

A New Industrial Base

We are entering an era of increasedpotential for the commercialization ofcomputer assisted surgical tools andrelated technologies.

If we are to realize the potential forimproving patients’ outcomes, thecommercialization of these emergingtechnologies will be an important steptowards making these tools available toa broader surgical audience and in turnhelp more patients.

This step will be important to thelonger term sustainability of theentire area of computer integratedsurgery and holds the potential toestablish Western Pennsylvania as aworldwide leader not only inresearch and development, but alsoin transferring technology to thecommercial sector resulting in a newindustrial base for Pittsburgh andWestern Pennsylvania. Towards theseends, CASurgica, Inc. was recentlyestablished as the commercial limb ofthe MRCAS program with the goal tocommercialize the next generation ofComputer Assisted Surgical toolsand technologies.

The Impact on HealthcareDelivery in Pittsburgh and theNation

Our program is positioned to establishan example for the country on howcontinuous process improvement andcomputer assisted tools could result inhigh quality, cost-effective healthcareprovided in a patient friendly environ-ment. In addition, our program has theopportunity to be both a regional andglobal authoritative body concerningclinical care and research in theseareas. Clinical and basic scienceresearch funding would be increasedbecause of the focus on solving real cli-nical problems. Finally, the opportuni-ties in technology transfer and partne-ring with commercial entities wouldlead to establishment of a new indus-trial base for Pittsburgh and WesternPennsylvania.

Our team effort, through the existinginterdisciplinary MRCAS clinical andresearch programs and educationalactivities is uniquely positioned toachieve all of these goals making thePittsburgh region an international lea-der in the areas of medical robotics,surgical navigation and computer assis-ted surgical technologies and a clinicalcenter of excellence that will be knownlocally, nationally and internationally.Contact Information:

Upcoming MRCAS RelatedEducational Activities

Educational activities play a significantrole in raising awareness of computerassisted surgical technologies, andexchanging information about the stateof the art, current research and deve-lopment.

The fourth annual North AmericanProgram on Computer AssistedOrthopaedic Surgery (CAOS/USA2000), will be held from June 15 to 17,


Contactinformation

If you would like additionalinformation or if you wouldlike to visit our MRCAS pro-gram, please call:(412) 623-2673or explore our web sites atwww.cor.ssh.edu

www.mrcas.ri.cmu.edu

or contact:Dr Anthony M. [email protected]

Research Office:Centers for Medical Robotics &Computer Assisted SurgeryUPMC Shadyside5200 Centre Avenue, Suite 309,Pittsburgh, PA 15232Phone (412) 623-2673Fax (412) [email protected]

www.cor.ssh.edu

www.mrcas.ri.cmu.edu

MRCAS Team Members atCarnegie Mellon Universityand UPMC Shadyside:Laura CassentiKaren CwynarAnthony M. DiGioia III, MDKaigham Gabriel, PhDBranislav Jaramaz, PhDTakeo Kanade, PhDRichard LaBarca, MS Timothy J. Levison, MSYanxi Liu, PhDJames Moody, MSPatrick Muir, PhDConstantinos Nikou, MSFrederic Picard, MDCameron Riviere, PhD


2000 in Pittsburgh. Dr DiGioia willchair CAOS/USA 2000. The Programwill emphasize state of the art techno-logies and perspectives on the rapidlyevolving field of computer assistedorthopaedic surgery. The conference isdesigned for practicing orthopaedicsurgeons and will educate participantson computer assisted and image gui-ded surgical techniques and roboticassistive devices. CAOS/USA will alsopresent the most current views on theimpact of computer assisted surgicaltechniques on the clinical and surgicalroutine in several orthopaedic subspe-cialties and promote a new partnershipbetween surgeons, technologists, andindustry as a critical foundation for thesuccessful integration of these tech-niques into routine clinical practice.

Dr DiGioia will also co-chair the thirdinternational Medical Imaging,Computing, and Computer AssistedIntervention (MICCAI) conference onmedical robotics, imaging and compu-ter assisted in Pittsburgh, October 11-14, 2000. Topics to be addressed at theevent include clinical applications ofcomputer technologies and systems,computer-assisted intervention sys-tems and robotics, as well as medicalimaging and computing for multiplesurgical and medical subspecialties.

For information on the CAOS/USA 2000 event

visit www.caosusa.org

and for MICCAI 2000 visit

www.miccai.org

For additional information on CAOS/USA

2000 and MICCAI 2000, you can also contact:

Preferred Meeting Management, Inc.

2320 6th Avenue, San Diego

CA 92101-1643, USA

Phone (619) 232-9499,

Fax (619) 232-0799

Establishment of theInternational Society forComputer Assisted OrthopaedicSurgery (CAOS-International)

The area of computer assisted ortho-paedic surgery has become so activeworldwide that it was time for a for-mation of a society that will enableexchange of ideas and contacts andserve to facilitate future collabora-tions. Dr Anthony DiGioia and theMRCAS program in conjunction withDr Lutz Nolte from the University ofBern-M.E. M¸ller Institute were ins-trumental in establishing the first everInternational Society for ComputerAssisted Orthopaedic Surgery (CAOS-International). The Society will haveheadquarters in Bern, Switzerland andthe North American office will be hou-sed at UPMC Shadyside Hospital. DrDiGioia is a founding member and waselected as the Inaugural First Vice-President of the Society. Dr BranislavJaramaz, also from the MRCAS pro-gram, will serve as Treasurer. The FirstCAOS-International Conference willbe held in Davos in 2001. The 2002meeting will be in North America andhosted by Dr DiGioia.

The purpose of this non-profit organi-zation is to bring together those indi-viduals throughout the world, who, bytheir contributions and activities in theareas of research, clinical study, and cli-nical use, have or are interested incomputer assisted orthopaedic sur-gery. Its further purpose will be toserve as a forum for the exchange ofinformation of both an investigativeand clinical nature which relates topreoperative planning, intraoperativeexecution, postoperative follow up andclinical outcomes by means of compu-ter assistance. The Society also aims topromote a new partnership betweenorthopaedic surgeons and technolo-gists as a necessary basis for the suc-cessful integration of computer assistedsurgical tools and techniques into thedaily clinical routine.

For information on the CAOS-

International/USA 2000 event visit

[email protected]

American Academy ofOrthopaedic Surgery Establishesa Special Interest Group onRobotics and Computer AssistedOrthopaedic Surgery (RCAOS)

The American Academy ofOrthopaedic Surgeons (AAOS) hasrecognized the potential impact ofcomputer assisted surgical tools andrelated innovations on surgical prac-tice. An AAOS sponsored Robotics andComputer Assisted OrthopaedicSurgery/Special Interest Group(RCAOS/SIG) has been established byDr DiGioia in 2000. RCAOS will sup-port the exchange of information instate-of-the-art techniques and pers-pectives in this rapidly evolving fieldincluding the areas of robotics, surgicalsimulators and planners, intra-opera-tive navigational systems and hybridreality. The first RCAOS/SIG Meetingwas held during the recent 2000 AAOSConference and attended by an enthu-siastic group.

RCAOS/SIG is open to all orthopaedicsurgeons and will assist participants tomore effectively understand and relaterobotics, image guided and computerassisted surgical systems to clinicalorthopaedic practice; demonstrate cur-rent clinical applications using RCAOStechnologies; obtain an internationalperspective on the current state-of-the-art as well as future developmentsplanned for computer assisted surgerysystems; and identify the clinical andtechnical issues and trends in roboticsand computer assisted surgery. ■

Dr Anthony DiGioia


An 89-year-old woman presented withintractable low back pain and weaknessin the L5 innervated musculature. Shealso complained of neurogenic claudi-cation after ambulating for 50 meters.

Lateral radiographs revealed multile-vel disk degeneration at L2-L3, L3-L4,and L5-S1. There was a degenerativespondylolisthesis at L4-L5 but normalalignment on the AP view.

Lateral myelography revealed a com-plete block at L5 and multilevel centraland foraminal stenosis was confirmedby CT scan. In light of the patient’sage, we attempted to perform as mini-mal of a surgical procedure as possible.The procedure consisted of a decom-pressive laminectomy from L2-L5 aug-mented by fusion of the unstable seg-ment (L4-L5) with Twinflexinstrumentation. ■

Christian Mazel, MDHead of the Orthopaedic andSpinal Surgery department

Institut Mutualiste Montsouris42, boulevard Jourdan75014 Paris FRANCE

Phone +33 1 56 61 62 63Fax +33 1 56 61 63 37

[email protected]


Degenerative spondylolisthesisassociated with lumbar stenosis

By Dr Christian MAZEL (IMM Choisy - PARIS) ■

clinicalcases

AP/lateral preoperative x-ray

AP/ lateral postoperative x-ray

AP/lateral preoperative myelography

CT scan

clinicalcases

A 56-year-old woman presented with asix-month history of left-sided sciatica,neurogenic claudication, and a footdrop. She also noted shooting painswith any sudden change of position,which were interpreted as evidence ofdynamic instability.

Radiographic examination revealedsevere disk degeneration at L5-S1,early degeneration at L3-L4 with slightanterolisthesis, and severe stenosis ofthe left L5-S1 foramen. EMG confir-med compression of the left L5 nerveroot and dynamic radiographs showedinstability at L3- L4, and L4-L5.

On October 18, 1995, wide left L5-S1laminotomies were performed fordecompression. Fusion from L3 to thesacrum was performed using Twinflexinstrumentation.

Three months postoperatively thepatient was able to walk for an hourwithout pain, and at 12 months’ follo-wup, the fusion had consolidated,

although the lumbar lordosis had notbeen completely restored.

The patient was quite satisfied with heroutcome despite some mild persistentbilateral sacroiliac discomfort. ■

Philippe Bedat, MDCabinet médical

36, avenue Théodore Weber1208 Genève SWITZERLAND

Phone +41 22 736 0902Fax +41 22 736 0494

[email protected]


Lumbar canal stenosis and instabilityBy Dr Philippe BEDAT (Genève SWITZERLAND) ■

Post-operative X-rays

Preoperative functional saccoradiculography

technologiesNew X-ray detector

Millions of x-rays areperformed each year. For

instance, the treatment of achild with scoliosis requires as

many as four x-rays per year.However, radiography is not aharmless procedure, as it must

be remembered thatconsiderable doses of

irradiation are absorbed bythe human body.

CONSEQUENTLY, since thebeginning of the 1980s, some

efforts have been devoted to designingsystems based on digital amplifiers andlaser images in which conventionalfilms are replaced by photosensitivecassettes. These devices reduce theirradiation dose by twenty per cent.The government agencies have alsostressed the importance of medicalradiation exposure, with recent EUR-ATOM recommendations from ICPRand the european community. Thework conducted by Georges Charpak(Nobel Prize for Physics in 1992) onthe proportional multiwire chamberhas led in the early nineties to a lowdose prototype which was clinicallytested at Hopital St Vincent de Paul,Paris, on children and teenagers. Thestudy showed unambiguously the capa-city of the prototype to provide goodquality radiographic images at a patientdose reduced by up to 20 times.

The original feature of this apparatus isits detector, a proportional multiwirechamber, designed and developed byCharpak for nuclear physics experi-ments at CERN, for which he wasawarded the Nobel Prize for Physics in1992. The device is based on the detec-tion of X rays in a gaz, here xenon andCO2, conversion into electrons andsubsequent amplification. Its major dif-ference with other X ray detectors is itssensitivity to individual X photons,making it a great detector for low doseexposures. The detector is linear, and isscanned together with the X ray tubealong the region of interest. To reduceall radiations due to scatter, two linearcollimators ensure a flat fan beam thatis perfectly adjusted to the lineardetector dimensions. That methodallows a total suppression of scatter, asonly the slice of the body that is expo-sed at a given time receives radiation.

In the prototype tested in 96, eachpixel of the detector was made of a 5cm long wire connected to an amplifier,discriminator and counter. The wirepitch was 1,2 mm, resulting in a reso-lution of about 0,6mm after signal pro-cessing. The digital data are then accu-mulated and displayed on a personalcomputer for clinical analysis. All fea-tures of a digital system, such as auto-matic density measurements, distancemeasurements and digital zoom areavailable with such a system. Thedetector is a true digital one, wherethere is no need for digitization or laserscanning. Data from the detector canalso be easily integrated into conven-tional digital radiology systems (repro-duction, transmission, filing, etc.).

Biospace, the company created byCharpak to derive biomedical imaging

systems from innovative detector tech-nologies, is currently developing anew system for low dose radiology.Using a new patented technologybased on micropattern detectors, thenew system will have the low dose fea-tures of the first protoype together witha higher resolution and scanningspeed. The product in development isa two heads instrument, in which twosimultaneous, perpendicular (front andside) X ray radiographs are taken. Forspine examinations, the pratician willhave the possibility to analyze thesetwo planar views as well as a tridimen-sional reconstruction of the spine, afeature currently developed by theLaboratoire de Biomécanique ofENSAM, Paris in collaboration withBiospace. First results with the newdetector technology showed unprece-dented high morphometric precision inthe 3D reconstruction of vertebrae.Besides being a low dose radiologyequipment, the new development couldbe a good alternative to highly irradia-ting CT scan exams for spine exams. ■


Nobel Prize Winner,Pr Georges Charpakcontribution to medicineA new X-ray detector from nuclear physics

communicationWhat is Biomechanics ?Thank you for your contribution !

We will see you next year…



ARGENTINADr Yvan R. AYERZADr Juan Pablo BERNASCONIDr Pedro Ariel COLLDr Alysudro Cesar D’INNOCENZODr Boan OSVALDO FERNANDEZDr Frederic J. GELOSIDr Felipe Zubiaur LANARIDr Carlos Aroldo LEGARRETADr Jose Luis MONAYERDr Luis A. PATALANODr Pablo PLATERDr Victor G. RAMANZINDr Gustavo RAMIREZDr Roberto Carlos RODRIGUEZDr Gabriel ROSITTODr Victor ROSITTODr Tomas RÜDTDr Eduardo SEMBERDr Pablo Mario SIRNADr Carlos A. SOLADr Edouardo Angel SOSADr Gustavo Roberto ZISUELA

BELGIUMDr Henri COSTA*Dr Guido DELEFORTRIEDr Damien DESMETTE*Dr Sabri EL BANNA*Dr Jean-Paul FORTHOMME*Dr Jean LEGAYEDr Frédéric MATHEIDr Yves RYSSELINCK

BRAZILDr André Rafael HÜBNER

CANADAPr Jacques DE GUISE

CHINAPr John LEONG

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FRANCEDr Christian MAZEL*Pr Serge NAZARIANPr Michel ONIMUSDr François PODDEVINDr Olivier RICARTPr Gérard SAILLANTPr Jacques SENEGASPr Wafa SKALLI*Dr Joël SORBIER*Pr Jean-Paul STEIB*Dr Alexandre TEMPLIER*Dr Richard TERRACHER*Pr Jean-Marc VITAL*

GERMANYDr Jens DÄNENNBERGDr Ferdinand KRAPPELPr Andreas WEIDNER

GREECEDr Panagiotis KOROVESSISPr Demetre KORRES*

HUNGARYDr Tamas ILLES*

ISRAELDr CASPI

ITALYDr Flavio BADODr Paolo BONACINADr Luigi CATANIDr Vincenzo DENAROMr. Charles-Marc LAAGER*Dr Tonino MASCITTIPr Giovanni PERETTI*Dr Carlo PIERGENTILIDr Dario RODIODr Michele Attilio ROSA

JAPANDr Kiyoshi KUMANODr Junichi KUNOGI

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THE NETHERLANDSDr Willem F. LUITJES

PORTUGALDr Joao CANNASDr Luis DE ALMEIDA

ROMANIAPr Mihai JIANU

SENEGALDr Seydina Issa Laye SEYE

SOUTH AFRICADr Johan WASSERMAN

SPAINDr Fernando ALVAREZ RUIZDr Diego BRAGADO NAVARRODr Sergio CABRERA MEDINADr Alfonso CAMPUZANODr J.M. CASAMITJANA FERRANDIZDr J. Ignacio CIMARA DIAZDr Jose Maria CORBOCHO GIRONESDr Alvaro DE BLAS ORLANDODr Jose Antonio DE MIGUEL VIELBADr Angel Jorge ECHEVERRI BARREIRO*Dr Manuel FERNANDEZ GONZALEZDr Fernando FERNANDEZ MANCILLADr Luis Antonio GARCIADr Antonio GIMENEZDr Francisco GONZALEZDr Ernesto GONZALEZ RODRIGUEZDr Angel GONZALEZ SAMANIEGODr Cesar HERNANDEZ GARCIADr Carlos HERNANDO ARRIBASDr Eduardo HEVIADr Juan HUERTADr Alberto ISLA GUERRERODr Manuel LAGUIADr Rafael LLOMBART AISDr Juan Antonio LOZANO-REQUENADr Carlos LUNADr Antonio MARTIN BENLLOCH*Dr Jose Ignacio MARUENDADr Cesar PEREZ JIMENEZDr Enrique RODA FRADEDr Manuel SANCHEZ VERADr Hugo SANTOS BENITEZDr Jose Luis SOPESEN MARINDr Agustin VELLOSO LANUZADr Javier VICENTE THOMASDr Julio Alfonso VILAR PEREZ

SWITZERLANDDr Philippe BEDAT*Pr Michel DUTOIT*Dr Bernard JEANNERETDr Denis KAECHPr Thierry SELZ

SYRIADr Taha ALOMAR

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USADr Michael ALBERTDr Patrick BERTRANOU*Dr Fabien BITAN*Pr Jean-Pierre FARCY*Dr Eric JONES*Dr David LANGEDr Vincent J. LEONEPr Joseph MARGULIESPr S.M. REZAIANDr William RODGERS*

* full members being entitled to sponsor

AArrggooss’’ mmeemmbbeerrss lliisstt


OOrrggaanniizzaattiioonn cchhaarrtt

ChristianMazel, MD

President

Jean-Paul

Forthomme, MD

Vice President

AlexandreTemplier, Msc, PhD

General manager

PierreKehr, MD

Executive secretary

AlainGraftiaux, MD

Treasurer

Communication committee

Training committee

Evaluation committee

WafaSkalli, PhD

President of thecommittee

JacquesDe Guise, PhD

MichelDutoit, MD

AlainGraftiaux, MD

ChristianMazel, MD

Juan AntonioMartin, MD

HenryJudet, MD

PhilippeBedat, MD

PierreKehr, MD

Charles-MarcLaager, PhD

Jean-PaulForthomme, MD

HenriCosta, MD

Jean-PaulSteib, MD

President of thecommittee

Jean-PaulForthomme, MD

FranckGosset, MD

FrançoisLavaste, PhD

RichardTerracher, MD

Jean-MarcVital, MD

Argos SpineNews 3

Health & Medicine

Transcript of Argos SpineNews 3