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No. 2 2005

by Diane Damiano, PhD PT

EXPLORING COMPLEX MOVEMENTDISORDERS THROUGH SHAREDASESSMENT– new challenges through shared assessment

While the mission of the center as statedis hardly unique, the fact that it ishoused within the Department ofNeurology is somewhat atypical asmost similar clinical and/or researchfacilities have tended for the most partto be housed within orthopaedicdepartments. Applications for motionanalysis technologies within themedical field alone have beenexpanding rapidly in recent years notonly across clinical disciplines, butacross different diagnoses and withrespect to other types of movementdifficulties beyond level gait at a self-selected speed (see Figure 1). Ourfacility is consistent with the abovetrends and in addition, we alsoexemplify the growing interest inrelating biomechanical changes to theunderlying neurophysiology of central

nervous system disorders. The SMAC houses a Vicon 612 MotionSystem with eight M2 cameras andworkstation, Polygon and BodyBuildersoftware, all provided by a grant fromthe National Center for ResearchResources which requires that thesystem be requested and utilized by ateam of at least three NIH-fundedinvestigators. These individuals includeJanice Brunstrom MD, a pediatricneurologist who is the Medical Directorof the facility, Diane Damiano PhD, aphysical therapist and researcher whoprimarily evaluates and studiesindividuals with cerebral palsy incollaboration with Dr. Brunstrom andothers, Joel Perlmutter MD, aneurologist and senior scientistrenowned for his work in adultmovement disorders particularly

Parkinson Disease, and John McDonaldMD PhD, a well-recognized spinal cordresearcher/physician who now headsthe International Center for Spinal CordInjury at Kennedy-Krieger Institute inBaltimore. In addition to the ViconMotion capture system, the SMAC alsohas two Kistler force plates, a Noraxon16 channel EMG system withMyoResearch software, a Biodex System3, and a touch screen computer forpatient questionnaires, among otherquantitative assessment instrumentsand tools.

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Read THE STANDARD online at www.viconstandard.org

The Shared MovementAssessment Center (SMAC) in theDepartment of Neurology atWashington University specializesin the analysis of individuals withcomplex movement disorders forboth clinical and researchpurposes. As an integral part ofthe Cerebral Palsy Center at StLouis Children’s Hospital, theprimary goal of our researchefforts is to improve the lives ofpersons with cerebral palsy byenhancing their motorcapabilities. Dr. Brunstrom reviewing a clinical study with Julie Weber, the research physical therapist. Looking on is our

administrator, Freda Branch.

This movement assessment center wasthe vision of Diane Damiano, who waspreviously the Research Director of theMotion Analysis and Motor Perform-ance Laboratory in the Department ofOrthopaedics at the University ofVirginia before coming to WashingtonUniversity in St Louis in 2000. Herresearch focus has been almostexclusively on characterizing motorimpairments in children with cerebralpalsy and on evaluating the effects ofexisting or novel interventions on gaitand gross motor function. Several yearsago, she and her colleagues challengedthe conventional wisdom that strength-ening was contraindicated for thosewith spasticity and they have sinceshown that direct muscle strengtheninghas a clinically important effect onmotor performance in these individualswith no evidence of worsening spas-ticity. In fact, intense physical activitymay actually decrease spasticity, anintriguing hypothesis that wasproposed and recently tested by Dr.

McDonald in collaboration with Dr.Sadowsky and Dr. Damiano in a projectfunded by the Christopher ReeveParalysis Foundation. Using resistancetorque and EMG measurements, theseinvestigators demonstrated that, inaddition to many other positive effectson health and function, subjects withspinal cord injuries who regularly usedan FES-cycle had significantly lowerspasticity and less of a need forspasticity reducing medication com-pared to age and injury matched non-exercising controls. The clinical population we serve at theShared Movement Assessment Center isvery diverse and includes not onlychildren with cerebral palsy, but hasalso included children and adults withother relatively common, rare, or as yetundiagnosed neurological deficits. Ourinterest also extends beyond (above) thelower extremity and we regularlyemploy the full body gait model incombination with EMG to evaluate

dystonic posturing in the trunk andupper extremities. However, as initiallyintended, we are predominantly aresearch facility even though ourclinical and research interests areinextricably linked.One of the first novel interventionstudies we conducted in our now two-year old center was an investigationlead by Dr. Janice Brunstrom on the useof levodopa for children with hyper-tonic cerebral palsy (CP). This project,funded by a Young Investigator Awardfrom the Child Neurology Society,tested the hypothesis that many of themovement abnormalities in CP whichare classically attributed to spasticitymay actually be due to dystonia andwould therefore respond positively to amedication that only addresses thelatter symptom. Dr. Brunstrom believesthat dystonia is far more common in CPthan the 20% previously reported. Wehave conducted an open label trial of ashort term course of levodopa on ninechildren with a diagnosis of spasticcerebral palsy who also demonstratedabnormal postures or movementpatterns at rest or when attempting toperform various motor tasks thatresemble those seen in persons withprimary dystonia. Our two main out-come measures were upper extremitykinematics and lower extremity balancemeasures. Since no single ‘standard’upper extremity 3-D kinematic modelyet exists, we sought permission to usethe one developed by Drs. George Raband Anita Bagley from the SacramentoShriners Hospital and adapted to Viconmotion capture systems by Ms. RobinDevorak from the Portland ShrinersHospital. We chose two upper extrem-ity reaching to target tasks, one whichemphasized accuracy and one which

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Picture of Lab Staff including(left to right) Julie Weber,Julie Anderson and Cole,Jason Wingert and DianeDamiano. Far wall is a muralof Forest Park in St Louis bytwo young local artists.

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Figure 1.A view of a patient in thelaboratory who is beingassessed on ramp ascentand descent.

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emphasized speed of movement, and arapid repetitive elbow flexion-extension task utilized previously byDr. Amy Bastian, now of Kennedy-Krieger, as described in a publishedcase study on the use of levodopa in anindividual with CP with Dr. Brunstromand colleagues, and which wereadapted from Optitrak to our Viconsystem. Figure 2 shows a stick figurefor the dominant upper extremity‘reach to target’ task in the sagittalplane with the target position shown inblue. The main output parameters weevaluated were peak wrist velocity (seeFigure 3), 3-D wrist path and endpointerror as the person attempted to holdthe finger position on the target.Consistent and statistically significantimprovements were noted in theseparameters as a result of the medicationat both freely chosen and fast reachingspeeds; however, these were notassociated with functional gains on theMelbourne Assessment of UnilateralUpper Limb Function. We also evalu-ated tandem gait performance beforeand after medication on those subjectswho were independently ambulatory.Based on the results from our pilotstudy, a larger, longer durationcontrolled trial is being planned. We are also nearing completion of apilot study funded by the United

Cerebral Palsy Research and EducationFoundation testing the hypothesissuggested by Allison Arnold, ScottDelp and their colleagues at StanfordUniversity that lower extremityextensor strength training alone willimprove the 3-D kinematics of crouchgait. Specifically, they proposed that asa result of intense strengthening, midstance knee and hip position will be ingreater extension with a concurrentreduction of stance phase hip internalrotation and adduction, and ankledorsiflexion, if excessive. Future goalsare to extend this investigation andperform dynamic simulations incollaboration with Arnold and Delp tomodel and predict which patients aremore likely to respond positively tostrength training and which may bemore successfully treated throughsurgical or other interventions.Two new investigations fundedprimarily though the NIH (NINDS and NCMRR) are just now underway in our center and involve close collabor-ation with neurologists and neuro-scientists, specifically Dr. Brunstrom,Dr. McDonald, and Dr. Harold Burton

who is an expert on somatosensoryfunction and functional brain imaging.The first project involves the character-ization of sensorimotor function incerebral palsy and its relationship to sensory processing in the brain. Jason Wingert, a doctoral candidate inthe Movement Science Program atWashington University who has been inthe center since its opening, hasreceived fellowship awards from theNIH and the Foundation of PhysicalTherapy to help support this project inaddition to support from UCP. Thesensory testing includes precise quanti-fication of tactile discrimination andproprioception in both the upper andlower extremities which will be cor-related to temporal-spatial and kine-matic gait performance during free andfast speed walking with and withoutvision of one’s lower extremities using‘dribble’ glasses which allow one tolook forward but not down (See Figure4 for: a) photo of the dribble glasses andb) the proprioception testing device).Using the full body COM model anddual force plates, we will also evaluatestanding balance with and without

Figure 2.Sagittal view of upper extremity ‘reach to target’ task in person withcerebral palsy. The red dots indicate the pointing finger and wristmarkers, and the blue dot indicates the target. �

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vision – in essence, a quantitativeRomberg Test. We hypothesize thatsensory performance and processingwill be deficient in CP compared tonormal and that sensory function willbe related to motor performance. Thesecond investigation is focused onquantifying the effects of a novelintervention in CP, motor-assistedcycling, on lower extremity coordin-ation during reciprocal lower extremityactivities such as active cycling andoverground walking, modeled after theinvestigations by Drs. McDonald andSadowsky on the use of FES-cycles inpatients with spinal cord injuries. As asecondary goal, Dr. Burton will lead thefMRI investigation of potential changesin cortical activation in response to astandardized lower extremity sensorystimulus before and after the intense

training. We are testing the hypothesesof whether imposed fast reciprocalmovements alone, in the absence ofelectrical stimulation, can alter spinalcircuitry and drive changes in thespatial extent and magnitude ofactivation in the motor cortex.Other important members of our teaminclude Julie Anderson (Witka) who isnow our part time engineer in additionto being a full-time new mom to Cole(See lab photos – Figures 5 & 6); JulieWeber is a research physical therapistwho plays an integral role in theassessment of both clinical and researchsubjects and Freda Branch who headsthe administrative aspects of thecerebral palsy center in general as wellas for our facility. Our program isobviously very dependent on strong

collaboration among our center’s teamand ‘outside’ clinical and basicscientists at Washington University andat other hospitals and universitiesacross the country. In addition toprojects we have initiated in our center,other investigators are encouraged toperform studies here with our assist-ance, for example, another doctoralstudent in the Movement ScienceProgram mentored by Dr. JoelPerlmutter, recently completed a projectevaluating arm swing in relation lowerextremity step length and cadenceacross gait velocities in patients with mild Parkinson Disease comparedto age-matched healthy controls.Examples of nearly completed or newlyinitiated projects that involve multi-center collaborations include theFunctional Assessment Research Group(FARG) investigations led by Drs. ChetTylkowski and Donna Oeffinger atLexington Shriners Hospital, and anewly funded randomized placebocontrolled trial on hamstring botulinumtoxin injections led by Dr. Phil Gates ofthe Shreveport Shriners Hospital withDr. Brad Racette, a neurologist here atWash U, as the site PI. We arecommitted to the idea that advances inour understanding of movementabnormalities and the effects that treat-ments have on these abnormalitiesinvolve precise quantification, creativeexploration and extensive collabor-ation. We feel that the motion capturecommunity, in particular, has served asan excellent model of the pursuit ofexcellence in measurement and evalu-ation and of the willingness to shareinformation and expertise to move ourrespective fields forward. We appreciate this opportunity tointroduce our center to the Viconcommunity and would like to thankGerald Bishop and the STANDARDstaff for this interest and assistance. Ifanyone would like to share informationor to learn more about our center’sclinical and research efforts, please donot hesitate to contact us at (314) 286-1581 or at damianod@neuro.wustl.edu

Figure 4.A picture of (a) the ‘dribble glasses used to testhow much the loss of vision disrupts the gaitkinematics and temporal spatial features. Thesedata will be correlated with those obtained on (b) our quantitative device made in house thatmeasures lower extremity proprioception.

Figure 3. Data from a single subject with cerebral palsyshowing faster reaction time, greater peak velocityand less endpoint fluctuation after the course ofmedication

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(a)

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This is an image of the firstbrochure from Vicon. It willshortly take its place, along with aremarkable and interestingselection of equipment andaccessories tracking the history ofmovement analysis and itsdevelopment over the years, in thenew Vicon Museum. This ventureis gradually taking shape underthe expert eye of Vicon’sEngineering Director TomShannon who will act as theMuseum’s curator.

The oldest item currently ready forthe museum catalogue is a 1982First Generation Interface Unit.Vicon is currently shipping thesixth in the series to be improvedand upgraded over the years asmovement science has advancedand demands increased. If any STANDARD readers areable to locate an example of aCOTRON silicon tube camera(circa early 1980s) and its strobeunit (both painted an ‘unusual’shade of brown!), Tom would be

interested to hear from you. Thesewere the first cameras sold afterthose shown in the brochure. So, ifanyone can throw any light onthis, just let us know. Tom Shannon told THESTANDARD “In a future issue I hope to offer a personal acount of not only the significant but alsothe many minor decisions thatwere taken by a small team ofdedicated people developing thefuture of movement analysisthrough more than two decades”.

Check out the STANDARD website:www.viconstandard.org for archivedarticles, a library of clinical papersummaries, news and the Image Library, as well as the current content ofTHE STANDARD. If you have acolleague who would like to register for THE STANDARD it can beaccomplished easily online atwww.viconstandard.orgWe are always pleased to mention thepresentation or publication of ViconUsers’ papers, accompanied by theappropriate website connection ifapplicable and/or the publisher’sdetails. Please send title, author andpublication information with a shortsummary by e-mail to gbishop441@aol.comor post a copy of the paper itself to

Gerald Bishop, Editor, The Standard,Gerald Bishop Associates, HillviewHouse, New Street, Charfield, Wotton-under-Edge, Gloucestershire GL12 8ES,England.Incidentally, anyone searching forpublished papers can not only go to the“Papers” section of www.viconstandard.orgbut, for a wider search, to an extremelycomprehensive collection of academicand professional publications atwww.ingenta.com A recent check showedthat over 17 million papers were onlinethere from almost 30,000 publications. Asearch for “gait analysis” for example,produced a list of 905 and “Vicon”located 105. It is worth checking out.Finally, check out the NASA websitewww.nasa.gov which is packed with

interesting information. If you go to theHome page and type “ABF” into theSearch box you will arrive at“Anthropometry and BiomechanicsFacility (ABF)”. A click on this line takesyou to three choices – Equipment,Facilities and Projects. Click on“Projects” to see a list of variousinteresting aspects of NASA’s work.Among these is a project entitled“Evaluation of a full body scanningtechnique for the purpose of extractinganthropometrical measurements” (num-bered 12 in the list). Click on to see theVicon 612 10-camera system in action. A click on “Equipment” in the threechoices includes a description of theVicon system.

Editor’s Note

Adam and Nickywith the 3D probe

Ultrasound probe with 3D localiser

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Researchers at the One Small Step Gait Laboratory in Guy’s Hospibeen developing a 3D ultrasound system for the measurement of mmorphology using a Vicon 612, a primitive ultrasound scanner andProgressive muscular and bonydeformities are features of cerebral palsyand other childhood disorders. It isduring adolescence that the functionalmobility of children with theseconditions decline, with many losingtheir ability to walk in their late teens andearly twenties. It is likely thatdeterioration in muscle properties andthe compromise of the skeletal leversleads to this loss of mobility. If we had agood way of quantifying deformity atdifferent stages in the development of thechild we may be able to:

• Understand more of the naturalhistory of deformity development.

• Intervene at an earlier stage tomaintain function.

• Assess the effects of our interventionson local musculoskeletal deformity.

Medical ultrasound imaging has beenaround since the late 1960s, and is themost common imaging modality in thehospital environment. It has wide rangeof applications from assessing blood flowin the carotid artery to imaging tumoursin the liver. 2D ultrasound is a useful but

3-D IMAGING OF MUSCLES AND BONESby Nicola Fry, Adam Shortland.

One Small Step Gait Laboratory, Guy’s Hospital, London, England.

IMAGING

largely qualitative technique and insome areas it has been superseded bytomographic CT scanning and MRI. 3Dultrasound is a recent development buthas great potential in quantitativeimaging. 3D ultrasound is used routinelyto assess the growing foetus or to inspectinternal abdominal organs. Thesesystems have exceptional accuracy but ingeneral have a small scanning window.3D scanning of limb segments requiresthat the position and the orientation ofthe probe can be registered over largedistances. There are such freehand 3Dsystems available using magnetictracking technology, but if you have amotion laboratory, a video framegrabber, a friend who is an ultrasono-grapher, and a bit of time on your hands,you could make one yourself!The following step-by-step instructionsare targeted at those in the laboratorywith an engineering bent:STEP 1: Find or buy an analogue 2D B-mode ultrasound machine with a 5 or7.5 MHz linear array probe. Perfectlyadequate, new examples can be boughtfor as little as $15000, but you may beable to “borrow” one from your localradiology department. Often, theseanalogue machines are being thrownaway in favour of their hi-resolutiondigital counterparts. Make sure your

ultrasound machine has a compositevideo output. It is wise to include yournew purchase in a hospital-wide qualityassurance scheme.STEP 2: Construct a 3D localiser from theVicon marker kit. We attach 4x 14 cmmarker stems to a small Perspex™ block.It’s best to keep the markers a gooddistance apart (at least 20 cm) to reduceerrors. The Perspex™ block should bemachined so that it locks to the surface ofyour ultrasound probe.STEP 3: Fix the Perspex™ block to theprobe and secure it (we use tie-wrap)(see Figure). Connect the video output ofthe ultrasound scanner to your analoguevideo framegrabber (or to your firewirecard using a DV bridge).STEP 4: Before you can image in 3D,you’ll have to find the equation of the

physics of ultrasound and its safe usage.Get yourself a musculoskeletal ultra-sound atlas and a good anatomy bookwith lots of pictures. Now play with yournew toy, making sure you have all thenecessary ethical and institutionalapprovals.

ApplicationsThere are a number of ways in which youcan use your system to inform treatmentdecision-making and even get bettermotion analysis results!

Muscle morphologyThe need for an alternative to the passiverange of motion examination to measuremuscle deformity is clear. Passive ROMis the primary tool used for treatmentselection across the world yet theexamination has poor intra- and inter-rater reliability and cannot distinguishwithout ambiguity the muscles ormuscular components responsible for alimitation in joint range.There is poor correlation between thestatic measurements of the clinical exam-ination and the dynamic measurementsfrom analysis of the child’s movement,possibly because the factors that governactive and passive movements are not equivalent. Unambiguous state-ments describing the dimensions ofmuscles would help us to separate the

contributions of deformity, weaknessand neurological deficit to the patient’smotor problems, directly informingtreatment recommendations.The Figure illustrates a 3D ultrasoundscan of the calf musculature of anormally-developing child and a childwith spastic diplegic cerebral palsy ofsimilar age. The hope is that bymeasuring the response of muscles todifferent treatments (eg strengthening,Botulinum toxin and surgery) in researchstudies, we will be able to determine theoptimum treatment for those attendingour gait laboratory for clinical andultrasonic assessment.

Anatomical modellingThe surface of bone can be identifiedunder ultrasound scanning easilybecause it reflects so much of the incidentacoustic power. This means thatreconstructions of the bone surface canbe made with 3D ultrasound. We haveused this technique to estimate the centreof the femoral head with respect to apelvic reference frame formed from theanterior and posterior iliac spines, andcompared the results to those from MRI.In the medio-lateral and anterior-posterior directions there is exceptionalagreement between the two methods(within a few millimetres), but workneeds to be done to improve the accuracy

Longitudinal slices through the calf muscles of (a) child with spastic diplegic cerebralpalsy and (b) a normally developing child. Skin surface is at the top of the images, kneeat the right and ankle on the left.

Longitudinal and transverse sections of a 3D volume containing the femoral head.

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tal, London, havemusculoskeletald video frame grabber.

plane of the ultrasound image withrespect to a local co-ordinate systemdefined by the probe-mounted markerset (3D localiser). This is a bit of achallenge, but you should find the paperof Fry et al. most helpful. Once you’veworked the calibration out, you will beable to find the global co-ordinates ofany pixel within the ultrasound image asyou move the probe through space.STEP 5: You need to write a computerprogram to construct a 3D image blockof voxels from the ultrasound videoimages and the co-ordinates of your 3Dlocaliser using an interpolation algo-rithm. There are a number of algorithmsyou could choose from (for review seeRohling et al. 1998); we use a nearestpixel algorithm and it seems to workwell. If you were very clever you couldwrite a plug-in for Vicon Workstation!STEP 6: To investigate and displaysections through your 3D volume youwill need to write a suite of programs, oryou can buy a program such as Analyseor IDL. In principle, you could write thecode in MATLaB but the memorymanagement of the very large matricesinvolved may be a limitation.STEP 7: If you are not well-acquaintedwith ultrasound machines then ask aradiographer to help you out and go ona course to familiarise yourself with the

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needs to be done to improve theaccuracy of the method in the inferior-superior direction.Our intention is to extend the techniqueto create partial surface reconstructionsof the skeleton to enable a preciserelationship between anatomical andtechnical reference frames to be foundfor individual subjects.

Bony morphologyIn the clinical environment, tibialtorsion, femoral anteversion and patellaalta are measured by palpation of bonylandmarks. Certainly, the lack ofreliability of these measures may en-courage a conservative approach tointervention being adopted. We haveconducted 3D ultrasound studies in vitroand in vivo which indicate that 3Dultrasound can measure femoral ante-version and tibial torsion reliably, and ingood agreement with the standard 3DCT method or MRI methods. Routine,serial measurements of bony torsionmade possible with ultrasound willenable us to evaluate the natural historyof skeletal deformity and its adaptation

after surgical intervention. In summary, 3D ultrasound is a safeimaging method that can be used toestimate the morphology of themusculoskeletal system. It is a usefuladjunct to 3D gait analysis for theassessment of patients with muscle andbony deformities.

ReferencesFry NR, Childs CR, Eve LC, Gough M, Robinson RO,Shortland AP. Accurate measurement of musclebelly length in the motion analysis laboratory:potential for the assessment of contracture. Gait andPosture 2003: 17: 119-124Rohling RN, Gee AH, Berman L. Automaticregistration of 3-D ultrasound images. UltrasoundMed Biol. 1998 Jul;24(6):841-54.

The first clinical motion lab in Norwaywas established at our hospital as late asJanuary 2002. Since then we have had anincreasing demand for gait analysis fromall over Norway. In the first year weperformed 60 analyses and this year wewill carry out approximately 150analyses. Our staff is expanding and wehave a multidisciplinary approach. Theteam consists of physiotherapists,orthotists and physicians (a childspecialist neurologist and an ortho-paedic surgeon). They all work part-timein the laboratory. We use a six-cameraVicon 612 system and two AMTI forceplates. So far we have been very satisfiedwith the system and support. In the nearfuture we hope to supplement ourresources with a video vector system and equipment for evaluating oxygenconsumption. From the start we have focused on aclose co-operation with the referringclinicians. We believe this is vital in orderto give the patient the best advice. Henceit makes the physicians generally more

VIDEOCONFERENCINGa new way of presenting reports by Bjorn Lofterod

Chief Consultant, Section for Child NeurologyRikshospitalet University Hospital,Oslo, Norway

Longitudinal section through a 3D ultrasound volume containing the patella and the proximal tibia.

as part of their treatment plan. Our ideology is that the result will not bebetter than the weakest link in the chain.The team in the laboratory therefore triesto take responsibility for the whole chainand to secure any weak part. To achievethis aim good communication betweenthe professionals that take part in thetreatment is necessaryWe make team conclusions. Howeverfinal conclusions are always made incooperation with the referring specialists,as they know the patient best and havegood knowledge of the rehabilitationresources in the county. All the patientshave a follow up post-treatment analysis. In order to evaluate ourrecommendations and results we arevery much concerned that the patientfollows the treatment plan outlined,including appropriate training and use oforthosis. Among patients receivingsurgery we now know ( through our ownstudy of this subject) that the surgeonsfollow the preoperative gait analysisrecommendations in more than 90 % ofthe cases. Our ambition to play a major role in the patient’s treatment plans has manychallenges, such as the effective com-munication of our recommendations. So far we have communicated theserecommendations to the referringspecialists at regular meetings, which wecall conclusion seminars. During thesemeetings the team presents the patientand analysis as displayed in a Polygonreport. In the first two years we alwayshad the seminars at our hospital. Duringthat period we experienced inconsistencyin attendance, and sometimes we foundthat the most important persons of thelocal rehabilitation team could not findtime to meet. There may be many reasonsfor inconsistency in attendance, but forNorway high travelling expenses andunstable weather conditions mean a lot.The country has only 4.8 million people,but is very long and narrow and it takesabout three hours to travel by air fromthe north to the south. In order to achieve our goal concerning aclose cooperation with the referringspecialists we had to look for anotherway of organising some of the conclusionseminars. It turned out that all thecooperating hospitals had a video-conference system, but like us theyhardly ever made use of it. Now, twoyears later, we have good experience inorganising gait analysis conclusionseminars by videoconferencing withhospitals all over Norway. One definiteadvantage is that it allows more peopleto take part, as there are no travellingexpenses to fund. The referring specialistcan involve colleagues and local mem-bers of the multidisplinary team in thediscussion. No travelling time means thatall involved can make their day moreefficient, and it is also easier to find timeto suit everyone when you are notdepending on public transport. All thesefacts ensure a better attendance, andhopefully a better final result for thepatient. When the attendance improves

more professionals learn about thepossibilities and restrictions of gaitanalysis. This may in future lead to abetter selection of high priority patients. Before each meeting we send ourPolygon report as a Word document by e-mail so all participants are prepared forthe subsequent discussion. We and ourcolleagues at the other end have twoscreens. On one screen we can see theteam from the other hospital (and viceversa), and on the other screen wepresent the patient by using an ordinaryPolygon report. Details and futuretreatment are discussed before a jointconclusion is drawn. We use about 30minutes for each patient presented andusually have two to three patients

presented at each meeting. We use aTandberg Videoconferencing System, butwe believe there are also other highquality products on the market. One disadvantage is that the screen issmaller than the screen we use when wepresent the reports at our hospital. Thismay blur the text in the report. Thepicture may also sometimes appear a bitunclear, but this is usually a question ofadjusting the system. Sound is rarely aproblem. Videoconferencing will ofcourse never be the same as having yourcolleagues in the same room, but it isclose to it and the organisation is very

convenient as a means of connectingspecialist services.There is a good cooperation between themotion labs in the Nordic countries(Denmark, Finland, Sweden andNorway). Three years ago we formed theNordic Vicon User Group. The groupmeets twice a year for professional andsocial networking. A result from thisteamwork is a Nordic normal referencedatabase. As far as I know we are theonly team in the group up to now thatuse videoconferencing in our clinicalwork. But future multicenter studiesbetween the four countries may be aperfect challenge for more active use ofvideoconferencing with less attendantless travel expenses. We may also be ableto establish joint discussions and consulteach other concerning difficult casesusing this useful method.

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❛ all involved

can make their day

more efficient ❜

The movement analysis team. From left: TerjeTerjesen (orthopaedic surgeon); Ann-Britt Huse(cpo); Bjorn Lofterod (child neurologist); ReidunJahnsen (physiotherapist); Monica Johannessen(physiotherapist); Ingrid Skaaret (cpo).

A view of the movement analysis laboratory with a subject under test.

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American Academy of Cerebral Palsy &Developmental Medicine (AACPDM) –International Cerebral Palsy Conference atthe Faculty of Medicine, University ofOulu, Finland from February 2 to 5, 2006;the 6th International Congress on CerebralPalsy in Bled, Slovenia, entitled “NewAdvances in Treatment of Cerebral Palsy”from April 20 to 22, 2006 and the 10thInternational Child Neurology Conferenceat the Bonaventure Hilton, Montreal,Canada from June 11 to 16, 2006. See www.aacpdm.org

American Academy of Orthotists &Prosthetists The 2006 Annual Meeting inChicago, USA will be held from March 1 to14 at the Hyatt Regency Riverside Center.Details on www.oandp.org

American Academy of Physical Medicineand Rehabilitation (AAPMR) The 67thAnnual Assembly will be at the at theHilton Hawaiian Village ConventionCenter, Honolulu, from November 9 to 12,2006. In 2007 it will be in BostonMassachusetts, USA at the SheratonMarriott Hilton Hynes Convention Centerfrom September 27 to 30, and in 2008 at theMarriott Convention Center, San Diego,California, USA from November 20 to 23.Information on www.aapmr.org

American Academy of Podiatric SportsMedicine The Annual Meeting in August2006 is to be held in Las Vegas, Nevada,USA. Information, as it becomes available,on www.aapsm.org

American College of Sports Medicine –The 53rd Annual Meeting in 2006 is inDenver, Colorado, USA from May 31 toJune 3. Details shortly onwww.acsm.org/meetings The 54th AnnualMeeting is currently planned for NewOrleans, USA from May 30 to June 2, 2007.

American Alliance for Health, PhysicalMedicine & Rehabilitation NationalConvention in 2006 is from April 25 to 29at the Salt Palace Convention Center, Salt Lake City, Utah, USA. ~Details on www.aahperd.org

American Physical Therapy Association(APTA) The APTA Annual Conference2006 will be held from June 21 to 24 inOrlasndo, Florida, USA. APTA website www.apta.org

American Podiatric Medical AssociationThe Annual Scientific Meeting in 2006 willbe from August 7 to 10 at MGM Grand,Las Vegas, Nevada USA. Postersubmissions by February 1, 2006. Main site www.apma.org

American Society of Biomechanics The next Annual Meeting will be fromSeptember 6 to 9, 2006 at the Virginia tech– Wake Forest School of BiomedicalEngineering & Sciences, Blacksburg,

Virginia, USA. Meeting website iswww.asb2006.org or e-mail for informationto aliceb@vt.edu The Society website iswww.asb-biomech.org

American Spinal Injury Association – the32nd Annual Scientific Meeting is at theWestin Copley Place Hotel, Boston,Massachusetts, USA from June 24 to 28,2006. Abstract submissions by Novewmber25, 2005. More details from www.asia-spinalinjury.org/annualmeeting

Association of Academic Physiatrists(AAP) 42nd Annual EducationalConference will be from March 1 to 4, 2006at the Hilton Daytona Beach OceanfrontResort, Daytona Beach, Florida, USA.Details from Lynn Lawson e-maillylawson@physiatry.org Telephone (317) 4313368; Fax (317) 823 9950. Main website www.physiatry.org

Association of Children’s Prosthetic andOrthotic Clinics The 2006 AnnualMeeting, from May 17 to 20, will be at theHyatt Regency in Sacramento, California,USA. The Shriners Hospital for Childrenwill be the host clinic. Information by e-mail from raymond@aaos.org Telephone(847) 698 1637; Fax (847) 823 0536. The main website is www.acpoc.org

Australian Physiotherapy Association14th Biennial Conference onMusculoskeletal Physiotherapy is atBrisbane Convention Center, Brisbane,Queensland, Australia from November 24to 28, 2005. Conference details:www.mpa2005.com.au or e-mailmpa2005@meetingplanners.com.auThe Association website iswww.physiotherapy.asn.au The Animal Physiotherapy GroupConference is being held December 3 & 42005 at the School of Veterinary Science,University of Melbourne, Victoria,Australia, Details are available by e-mailfrom rose.kraljak@physiotherapy.asn.auor by telephoning Rose Kraljak, APA on (03) 9536 9335; Fax (03) 9534 9199.

British Association of Prosthetists andOrthotists The BAPO Annual Conference12, to be held at SEEC, Glasgow, Scotland,UK, is from March 24 to 26, 2006. Detailson website www.bapo.com or Secretariattelephone +44 (0)845 166 8490

Canadian Physiotherapy Association The2006 Congress will be held from June 30 toJuly 2 at the Delta St John Hotel &Conference Centre in St John, NewBrunswick, Canada. Information fromwww.physiotherapy.ca/congress2006

Clinical Movement Analysis Society TheCMAS 5th Annual Conference will be heldon 23 & 24 March 2006 in Newcastle uponTyne, England. Information availableshortly on www.cmasuki.org

European Medical and BiologicalEngineering Conference (EMBEC) The3rd Conference is from November 20 to 25,2005 at the Congress Centre in Prague,Czech Republic. www.embec05.org

European Orthopaedic Research SocietyThe next EORS Congress will be June 7 &8, 2006 at the Istituti Ortopedici Rizzoli,Bologna, Italy. Abstract submissions byJanuary 15, 2006; early registration byMarch 31, 2006. Information by e-mail from fisiopat@ior.it and the website www.ior.it/eors06

European Paediatric Orthopaedic Societyis holding the 25th Meeting in Dresden,Germany from April 5 to 8, 2006 (year ofDresden’s 800th anniversary). The Meetingwill take place in the Congress Center,Hotel Westin Bellevue in Dresdenwww.westin-bellevue.de The main Societywebsite is. www.epos.efort.org and directlyfor information on the congress,submission of papers online etcwww.epos.efort.org/Dresden2006/index.asp

European Society for Movement Analysisin Adults & Children (ESMAC) The 15thAnnual Meeting is also the First JointESMAC/GCMAS meeting (GCMAS 11thAnnual Congress) and will be inAmsterdam, Netherlands from September25 to 30, 2006. Online abstract submissionfrom January 10, 2006 and abstractsubmission deadline March 15, 2006. Earlyregistration date is June 1, 2006. Moreinformation from j.harlaar@vumc.nl The2007 Meeting is planned for Athens,Greece. The main ESMAC website iswww.esmac.org

Human Factors and Ergonomics Societyof Australia The 2005 National Conferenceis in Canberra from November 21 to 23. Website www.ergonomics.org/au International Ergonomics Associationinformation by email from info@iea2006.orgincluding the IEA 2006 16th Congress fromJuly 10 to 14 in Maastricht, Netherlands.

International Federation of Foot & AnkleSocieties (IFFAS) The Seventh BiennialCanadian Orthopaedic Foot & AnkleSymposium will be April 8 & 9, 2006 at theMedical Sciences Building, Kings CollegeCircle, Toronto, Canada. Information e-mail iffas@globalfoot.org The main website is www.globalfoot.org

International Federation of SportsMedicine (FIMS) The 4th European SportsMedicine Congress from October 13 to 15,2005 will be at the Hawaii Grand Hotel,Lemesos, Cyprus. Contact Pyrgos CongressLtd, Nicosia, Cyprus – telephone 093572277 4157; fax 09357 2278 1031. The FIMSWorld Congress of Sports Medicine in 2006will be at the International ConventionCenter, Beijing, China from June 12 to 16.Information from the National ResearchInstitute of Sports Medicine in Beijing –telephone +86 (10) 6719 2750; fax +86 (10) 6719 2755; e-mail ligp@263.netThe FIMS website is www.fims.org

MEETING POINTS ...

International Society of BiomechanicsXXIst Congress will be from July 1 to 5 atthe International Convention Center,Taipei, Taiwan. Information beingcompiled on www.isb2007.org The ISB website is at www.isbweb.org

International Society for Biomechanics inSport The next International Symposiumwill be from July 14 to 16, 2006 at theUniversity of Salzburg, Austria.Telephone+43 662 8044 4884; fax +43 662 6389 4884.Information from isbs2006@sbg.ac.at Main ISBS website www.isbs.org

International Society ofElectrophysiology & Kinesiology The XVICongress will be held at the LingottoCongress Center, Torino, Italy from June 28to July 1, 2006. There will be a pre-Congress Workshop on June 28 and a post-Congress Course on Movement Analysisin Sport and Exercise on July 3 & 4 at theUniversity Institute for Movement Sciencesin Rome. Information from www.isek2006.it The main website is www.isek-online.org

International Society of Physical &Rehabilitation Medicine (ISPRM) The 4thInternational Congress from June 10 to 14,2007 is to be in Seoul, Korea and the 5thwill be held in Istanbul, Turkey. Moreinformation will become available at theSociety’s website www.isprm.org

International Society of Postural & GaitResearch The 2007 Conference is plannedfor Baltimore, USA. Information, as itbecomes available, on www.ispgr.org

International Society for Prosthetics &Orthotics The 12th ISPO World Congressis to be held from July 29 to August 3, 2007at the Vancouver Convention Centre inVancouver, Canada. Information from the ISPO Congress websitewww.ispo.ca/congress or from the presidentISPO Canada, Edward Lemaire, PhD,Institute for Rehabilitation Research andDevelopment 505 Smyth Road, OttawaON, Canada KIH 8M2, Telephone (813)737 7350 Ext 5592. Meanwhile the UKNational Member Society for Prosthetics &Orthotics is holding the next AnnualScientific Meeting in the UK on November4 and 5, 2005 at the Hilton Swindon, Great Western Way, Swindon, England.Details on www.ispo.org.uk ore-mail info@ispo.org.ukTelephone/Fax +44 (o) 141 560 4092

Japanese Orthopaedic Association The79th Congress will be at the PacificoYokohama from May 18 to 121, 2006.Information e-mail office@joa.or.jp The Association’s 21st Annual OrthopaedicResearch Meeting from October 19 to 20,2006 will be at Brick Hall, Nagasaki. The Association website is www.joa.or.jp

National Athletic Trainers Association(USA) The 57th Annual Meeting & ClinicalSymposia is planned for New Orleansfrom June 27 to July 1, 2006 and in 2007from June 26 to 30 in Anaheim, California,USA. Information, as it becomes available.from www.nata.org

Orthopaedic Research Society (ORS) –The 52nd Annual Meeting will be fromMarch 5 to 8, 2006 in New Orleans,Louisiana, USA. Abstacts online June 20 toAugust 22, 2005. In 2007 the Meeting willbe in San Diego, California, USA. See www.ors.org or e-mail ors@aaos.org

Scoliosis Research Society (SRS) – The40th Annual Meeting is from October 28 to30, 2005 with pre-meeting courses onOctober 27, at the Loews Miami BeachHotel, Miami, Florida, USA, and the 41st isplanned for September 13 to 16, 2006 inMonterey, California, USA. Information on SRS website www.srs.org

Society for Neuroscience The 36thAnnual Meeting – is planned for NewOrleans, USA in 2006 from October 21 to25, and the 37th in 2007 from November 3to 7 in San Diego, California, USA.www.sfn.org

World Confederation for PhysicalTherapy The 2007 International Congresson World Physiotherapy will be from June2 to 6, at the Vancouver Convention andExhibition Centre, Vancouver, Canada.Proposal submissions by January 31, 2006;call for abstracts available from January 1,2006 for submission by September 15,2006. Information onwww.wcpt.org/congress/index.phpThe main website is www.wcpt.org

Additional sites of interestAmerican Academy of Kinesiology &Physical Education www.aakpe.org American Academy of Pediatricswww.aap.org American Orthopaedic Society for SportsMedicine (AOSSM)Society website: www.aossm.org American Society of ExercisePhysiologists www.asep.orgAustralian Association of Exercise &Sports Science www.aaess.com.au Bone & Joint Decade (2000-2010)www.boneandjointdecade.org Canadian Association of Prosthetists &Orthotists www.pando.caCanadian Society for Biomechanicswww.health.uottawa.ca/biomech/csb/ Gait & Clinical Movement AnalysisSociety www.gcmas.orgInternational Federation for Medical &Biological Engineeringwww.ifmbe.org (Click on “Calendar”)International Organization of PhysicalTherapists in Women’s Healthwww.ioptwh.orgNorth American Society for PediatricExercise Medicine www.naspem.org Ontario Kinesiology Associationwww.oka.on.ca For Physical Therapy links through theUniversity of Sydneywww.library.usyd.edu.au Biomechanics World Wide (Useful links)www.per.ualberta.ca/biomechanicsFor world wide orthopaedic linkswww.freeortho.com/associations For other events refer also towww.gcmas.org/societies.html

11

LITERATUREUPDATEby Dr. Ed Biden, Institute of Biomedical Engineering,University of New Brunswick, Canada.

Recently there has been renewed interest in somelong standing challenges in motion analysis andthe first papers in this review look at a selectionfrom how-to-estimate muscle forces duringwalking based on EMG to how-to- measure foot tofloor forces during treadmill walking.

To begin, Bogey, R., Perry, J., Gitter, A., “AnEMG to Force Processing Approach forDetermining Ankle Muscle Forces DuringNormal Gait”, IEEE Transactions on NeuralSystems and Rehabilitation, Vol 13, #3 Sep2005 pp 302-310, describe experiments with agroup of ten normal adult males who had datacollected to track movements, forces and EMG.The motion capture system was a Vicon 512. Themoments around the ankle were computed usingconventional Newtonian methods. The EMGportion was done by collecting data, with fine wireelectrodes, for ten muscles crossing the ankle.The signals were used as input to a complexmodel which includes the geometry of the joint,and muscles surrounding it, and a Hill-basedmodel to estimate forces based on EMG. Theresults of the EMG estimates were then collapsedto estimate the net moments at the joint and thesevalues were compared favorably to the motionanalysis results. This paper represents one morestep on the path to being able to computeindividual muscle forces on a routine basis.

Cerveri, P., Pedottu, A., Ferigno, G.,“Kinematical models to reduce the effect ofskin artifacts on marker-based human motionestimation”, J. Biomech, Vol 38, 2005 pp 2228-2236 take us back to the ongoing problem of howto account for skin movement when what iswanted are the underlying motions of theskeleton. They use an approach which theydescribed originally in 2003 that uses KalmanFilters to estimate kinematic variables. A KalmanFilter is essentially a model of how the system isexpected, in this case the person moving, toperform. The actual measured data are thencompared to the model and the differences arereconciled. Their tests suggest that the methodcan be used with 2D data without explicitreconstruction of marker positions, and that thelocations of markers can be generated from thefilter models. The challenges of the technique arethat the Kalman Filter needs either an explicitmathematical model for the motion to bemeasured or a statistical model which providesempirical data about motions of the type. Thiswould seem to limit the applicability, particularlywhen 2D data are used, to movements inconditions which have been studied extensively inorder to provide these data.

continued overleaf

LITERATURE UPDATE continued

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It is interesting that Hlavorsen, K., Soderstrom,T., Stokes, V., Lanshammar, H.,“Using anExpanded Kalman Filter for Rigid Body PoseEstimation”, J. Biomechanical Engg, Vol 127,June 2005, pp475-483 also use a Kalman Filterapproach to modeling rigid body motion. Theirapproach assumes 3D coordinates are known anddevelops a model of the underlying motion and itsparameters. The particular strength the authorssee in their method is that it is particularly robust inestimating the motion of a segment when there aregaps in the marker record, a common problem inpatient measurement situations where motions donot follow typical patterns. Their method is linkedto the motion of individual segments and seemsquite able to be generalized.

More conventionally, Rivest, L., “A Correctionfor axis misalignment in the joint angle curvesrepresenting knee movement in gait analysis”,J. Biomech, Vol 38, 2005, pp 1604-1611describes an elegant technique by which thesmaller motions of varus-valgus angulation andab-adduction at the knee can be decoupled fromknee flexion in order to minimize cross talk.Developed based on Vicon captured data, themethod proposed is able to reduce “noise” in themeasured angles, resulting in tighter boundarieson the angle measurements.

Verkerke, G., Hof, A., Zijlstra, W., Ament, W.,Rakhorst, G., “Determining the centre ofpressure during walking and running using aninstrumented treadmill”, J Biomech Vol 38,2005, 1881-1885 tackle the problem of how tomake force measurements when using a treadmill.They provide a brief history of the development oftreadmill force measuring systems and identify akey problem as being how to separate left andright during double support. To address this, theysupport the treadmill belt using two independentforce plates, one on the left and one on the right.These force plates measure vertical load and areused to estimate center of pressure each time asample is taken. Estimates of center of pressureare accurate to about 6mm laterally and 20mm inthe fore aft direction which is sufficient to givereasonable measures of step width and length.They also found that they could extract timinginformation accurately from the instrumentedtreadmill. This method is a nice addition to thetools of movement analysis because it allowsassessment of multiple steps within a laboratorysetting.

Movement analysis produces a huge amount ofdata and many techniques are used to reduce theamount of data which must be presented. In manycases “scores” of various sorts are calculated.Flanagan, S., Salem, G., “The Validity ofSumming Lower Extremity Individual JointKinetic Measures”, J. Applied Biomechanics,Vol 21, pp 181-188 2005, look at how wellsummed measurements across joints correlatewith various sorts of task. They chose a simplebarbell lifting task and investigated how well sumsof various common kinetic measurements explainthe variability seen in their test subjects. Theimportant findings are not the details of what worksfor a barbell task, but rather the observation that,depending of what is used as the output measure,different kinetic measures had very different levelsof success in predicting them. The strongimplication is that before using any particularmethod when generating a “score” it is critical todo an assessment of whether the “score” isactually correlated with the outcome measure forthe specific task being measured. They cite theexample of a widely used score which turned outto be a very poor predictor when used in theirsimple lifting task.

The paper by Weber, D., Stein, R., Chan, K.,Loeb, G., Richmond, F., Rolf, R., James, K.,Chong, S., “BIONic WalkAide for CorrectingFoot Drop”, IEEE Transactions on NeuralSystems and Rehabilitation Engineering, Vol13, #2, June 2005, pp 242-246 provides a veryinteresting case study of the use of motionanalysis to assess novel technology. The personfeatured in this work has a foot drop secondary toa motor vehicle accident. To address his foot drophe has used a surface stimulation system forseveral years. For this study he also had “BION”stimulators implanted so that a comparison couldbe made. “BION”s are very small stimulatorswhich can be injected using a large needle andare activated by radio frequency signals externalto the body. The experiment consisted of a comparison of hiswalking ability without any aids, with ankle footorthoses, with surface stimulation and with theBIONs. A Peak Motus system was used to trackhis gait under all conditions. The individual walkedmarkedly better using the stimulation systems,and the BION implantable system workedcomparably to the surface simulation but withoutthe need for daily positioning of the stimulatingelectrodes.

On a completely different track, the paper byKobayashi, Y., Takashima, T., Hayashi, M.,Fujimoto, H., “Gait Analysis of People Walkingon Tactile Ground Surface Indicators”, IEEETransactions on neural Systems andRehabilitation, Vol 13, #1, Mar 2005 pp 53-59 isan indicator of how sophisticated and sensitivemotion analysis techniques have become. Theauthors used a Vicon 512 system to investigatechanges in gait when people walk over the sort ofpebbled surfaces which are used to warn visuallyimpaired individuals of the proximity of curbs,steps and so forth. I am sure that it’s not very longago that detecting such subtle changes wouldhave been viewed as impossible for motioncapture systems. That said, these investigatorswere able to show subtle but significantdifferences in toe height during swing as well aschanges in joint angles and moments as aresponse to the changes in surface.

I will conclude these reviews with Blemker, S.,Delp, S., “Three Dimensional Representationof Complex Muscle Architectures andGeometries”, Annals of Biomedical Engg. Vol33, #5, 2005 pp 661-673. This group is well knownfor development of complex models of musclesaround joints. This paper describes the next stepin development. Previously muscles were built upof many line elements. In the new model a finiteelement approach is used which can account forchanges in moment arm along the fibers.Modeling the fibers as 3D elements allowsprediction of interactions between fibers that hasnot been possible before. The authors describevarious “templates” which correspond to differentfiber geometries and allow the building up of verycomplex models. Full implementation of thesesorts of models into all the areas where they canpotentially be used will require extensiveverification over many subjects, a challenge whichthe authors acknowledge. This type of model,combined with data from experimental studiessuch as Bogey et al discussed at the beginning ofthis review, have the potential to allow motionstudies and joint mechanics studies to merge,resulting in measures and models which reflect theactual function of individual muscles.