[377] adjusted versus unadjusted foot orthoses in the ... · va medical center, bronx, ny dr....

For additional information on topics related to this category see the following Progress Reports: [2], [8], [9],[14], [85], [95J, [104], [148], [149], [150], [151].

[377] Adjusted Versus Unadjusted Foot Orthoses in the Preventionof Foot Ulcers in Diabetics

Stephen F. Albert, DPMVA Medical Center, Denver, CO 80220

Sponsor : VA Rehabilitation Research and Development Service (Project #607-RA)

Purpose—Preulcerative and ulcerative foot lesions indiabetics invariably occur at weightbearing sites withmaximum pressure . There is evidence to suggest thatcustom foot orthoses mitigate such pressures, presumablythrough their redistribution . We hypothesize that individ-ually adjusted orthoses reduce the incidence of footulcerations . We also suggest that the effectiveness oforthoses and their best adjustment are possible with"in-shoe" capacitive sensor measurements which notonly quantitate pressure, duration, and location, but canbe performed on an outpatient basis.

The purpose of this study is to : I) determine ifin-shoe foot orthoses control distribution of plantar footpressure in the stance phase of gait to such an extent thathyperkeratotic stance phase foot lesions are noticeablyaffected ; 2) determine if orthosis adjustments significantlyimprove distribution of plantar foot pressure in the stancephase of gait, and if further orthosis adjustments arenecessary with time ; and, 3) determine, in diabetic

patients who have previously ulcerated their feet, ifcustom foot orthoses (adjusted versus unadjusted)decrease the incidence of reulceration.

Methodology—Two study groups will be used . GroupOne will consist of 40 subjects randomly assigned to theadjusted orthotic group . Group Two will consist of 40subjects assigned to the unadjusted orthotic group. Theadjustments will be made as needed, following determi-nations of foot pressure distribution during the dynamicsof gait (pressure—NIcm2 , time—ms, and location incoordinates) . The measurements will be obtained monthlyusing "in-shoe" capacitive sensor measurements.

Implications—We anticipate that adjusted orthoses willprove superior to unadjusted ones in preventing pedalulcerations in the diabetic population . We also expect tofind that in-shoe measurements of foot pressure distributionis the best method for guiding the appropriate adjustments.

[378] Clinical Evaluation of the Vannini-Rizzoli Stabilizing Limb Orthosis

Joseph Binard, MD; Stanley Gordon, MD; A. Connor Higgins, MD ; Bernard A . Nemchausky, MD;Michael Vulpe, MD ; Robert R . Young, MD; Andrew Fischer, MD ; Andrea Dory, RN; Lester T. Richard, RK;

Yvonne Lucero, MD; Herbert Kent, MDJames A. Haley Veterans' Hospital, Tampa, FL 33612 ; VA Medical Center, Bronx, NY 10468 ; VA Medical Center,Memphis, TN 38104 ; Edward Hines, Jr. VA Hospital, Hines, IL 60141 ; VA Medical Center, Long Beach, CA 90822;VA Medical Center, West Roxbury, MA 02132

Sponsor : VA Rehabilitation Research and Development Service (Project #B597-EA)

Purpose—The purpose of this project is to evaluate the

lesions of the cord at, or caudal to, the mid-thoracicVannini-Rizzoli Stabilizing Limb Orthosis (VRSLO) as a

level.means to permit standing and ambulation, with a

Also included in the study is the establishment of theminimal expenditure of energy, in spinal cord injury

appropriate criteria for candidate selection, alteration of(SCI) patients with paraplegia or paraparesis due to

the treatment plans for those selected, selection of proper

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exercises, establishment of the duration of the client'sprogram, and incorporation of this information into theclinical application of the VRSLO or, as it is commonlyreferred to, "The Boot ."

Methodology—The Boot works solely by arrangementand rearrangement of body mechanics . Use of the Bootcauses plantar flexion of the foot and stabilization of theankle; the patient is taught extension of the knees, hips,and back to achieve a stable stance . When proper weight-shifting techniques are combined with stance, the personmay ambulate with a pendular motion of the unweightedlimb and an assistive device (e .g ., canes, walker, etc .) forsupport . SCI injuries ranging from C-6 to L-3 have beenfitted, but ambulation status obviously differs fromperson to person.

There are several important variables which corre-late with potential for success or failure . Patients withrecent, low-level injuries and no major joint contracturesor severe spasticity are good candidates . Persons must behighly motivated toward standing and walking, as well aswilling to devote approximately 2 months to the program,5 or more days per week.

Relative, but not absolute contraindications to par-ticipation include cardiovascular disease, history oflong-bone fracture within one year of fitting, and place-ment of rods for spinal stabilization (which may limitback extension). Obesity, uncontrollable spasticity,chronic skin breakdown, and fixed joint contractures aredefinite contraindications.

The program consists of extensive exercises on a matto facilitate weight-shifting movements, abdominalstrengthening, and general stretching of the limbs andback. Daily sessions in the standing frame help developtolerance for the upright position and allow further prac-tice of weight-shifting techniques . Therapists assist withand supervise these activities.

Training with the orthotic devices begins after 4 to6 weeks of the conditioning program . Patients are issuedtheir Boots, and adjustments to the laces and soles aremade to assure good fit and stability while standing . Bothorthotists and therapists work with the patient in thisphase. Candidates, in general, progress from usingparallel bars for support to walkers, forearm crutches,or even canes.

Further refinement of skills may incorporate stairclimbing, ramp walking, and car transfers, in addition toperforming activities of daily living (ADL) while stand-ing. Not all patients have, as yet, reached these goals;a major obstacle for some is adherence to the rigorous

program. For others, back or joint pain sometimes limitsduration of use of the orthosis.

Progress/Preliminary Results—James A. Haley Veterans'Hospital, Tampa, FL. The Tampa VA Hospital has beenapproved to accept 30 patients for evaluating the Rizzoliorthosis. Thus far, 19 patients have been accepted inthe research program . Ages range from 19 to 60 yearsold with length of injury from one year to 38 years.Levels of injury range from complete C-7 quadriplegia toL-1, L-2 paraplegia.

The Vannini-Rizzoli Boot has been very successful.Patients are ambulating with quad canes 60 to morethan 1,000 feet (average distance 300 feet) for a successrate of 80% . Some patients are capable of negotiatingstairs independently.

This new orthosis has increased independence,allowing patients who have been in wheelchairs for asmuch as 38 years to ambulate independently in theirhomes and moderate distances outside their homes . It haseliminated the need for some patients to make structuralchanges to their homes since they can ambulate indepen-dently. Several patients have stated that they have not hada urinary tract infection since using the Boots . Othershave stated that they do not need to look for a wheelchair-accessible hotel when on the road . These are just severaladvantages the Boot has given our patients.

VA Medical Center, Bronx, NY Dr. Vannini, devel-oper of the Vannini-Rizzoli Boot, visited our centerinitially to assess interested candidates for the program.She was accompanied by a therapist and prosthetist-orthotist who were involved in her program . Twenty-fourcandidates, recruited through efforts of our staff and theEastern Paralyzed Veterans Association, appeared.Although definitive criteria for admission into the pro-gram had not yet been finalized, 18 of these candidateswere accepted . Of the first 18 patients, 6 completed theprogram and were given the Boots to use outside of thehospital . The others had to drop out for variousreasons—the primary reason being their lack of endur-ance in mastering various stages of the protocol.

Subsequently, several more candidates entered theprogram ; at the present time, we have 9 patients usingthe Boots.

We are continuing the program, but have had only arare candidate . At the present time, we have two patientsactively engaged in the training process.

VA Medical Center, Memphis, TN. As of fall 1990, 54patients have been evaluated for the VRSLO and 25 havebeen selected, with an additional two patients in the

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evaluation phase . Of the total selected, 21 are paraplegicswith an injury level ranging from T-4 to L-3, completeand incomplete, and four are quadriplegics with injurylevels of C-6 to C-7, complete and incomplete.

Of the 21 paraplegics selected, the functional levelsare as follows : two require minor assistance for standingwith the use of parallel bars or walkers, five are indepen-dent in ambulation in the parallel bars, five are indepen-dent in ambulation utilizing a walker, one is ambulatorywith crutches, one is independently ambulating withbilateral quad canes, and one is independent in ambula-tion with a single quad cane and can also ambulatebehind a wheelchair. Of the paraplegics selected, twocan ambulate short distances with no assistive devicessuch as walkers or canes . There are also five paraplegicswho can negotiate stairs, and two paraplegics who with-drew from the study ; one for medical reasons and theother voluntarily.

For the quadriplegic group, the four patients selectedhave attained the following levels : two are independentlystanding with the use of a walker, one requires minimalassistance to stand in the parallel bars, and one has apermanent orthosis on order.

The preliminary results of the study have shown thatthe VRSLO is more widely accepted by the SCI clientsthan conventional bracing . The Boot is lighter in weight,more cosmetically acceptable, and easier to don and doffthan conventional bracing systems . It is also apparent thatthe Boot is more functional, and due to the ability toattain static equilibrium with proper fitting, that theknee joint is free and mobile with no external lock-ing mechanism.

Edward Hines, Jr. VA Hospital, Hines, IL . Ourexperience at Hines has been a mixture of results : somepositive, others not entirely satisfactory . Of 20 pairs ofBoots fitted, 9 persons appear to be daily users . At leastone person has sustained hairline tibial plateau fractures(possibly a result of tibial torsion in the Boots), and doesnot ambulate at present . One patient relinquished hisplace in our program to attend to a severely ill spouse;another was employed in research which did not allow anextended leave to master the orthosis . Obtaining assistivedevices with the length necessary to accommodate theadditional height of a person in Boots has limitedprogress in several cases.

VA Medical Center, Long Beach, CA . Thirty patientsaged 22-68 years are in this study. Spinal cord levels ofinjury vary from C-5 to L-l . Patient selection and otherpertinent data are given . Our results indicate a successrate of more than 90% . Acceptance of the Boot has been

extremely good . The average distance ambulated was100+ feet.

VA Medical Center, Brockton/West Roxbury, MA.Twenty-five patients were initially evaluated : 17 wereentered into, and 7 completed the study . After dischargefrom the intensive exercise program, patients were evalu-ated at least monthly for the first 3 months, and then atleast every 3 months. Of the seven who completed thestudy, four are ambulating at a community level and oneat the household level using canes . Five were unsuccess-ful in using the VRSLO to ambulate because contracturescould not be eliminated, skin breakdown occurred on thefeet, or a tibial fracture occurred after admission to thestudy but before the Boot arrived . Three of these"failures" were temporary . These patients will bereentered into the study after the musculoskeletal orcutaneous lesions heal.

Future Plans–$'A Medical Center, Bronx, NY Our ther-apists and orthotists are well trained and can handle newcandidates expertly. We anticipate relatively few newparticipants . However, the therapists will continue to doperiodic follow-up evaluation on all patients who havebeen issued the Boots, and we shall cooperate with theother five medical centers in achieving the goals andevaluating the effectiveness of this pilot program.

VA Medical Center, Brockton/West Roxbury, MA.Admission criteria will be liberalized to include olderpatients and those with lesions between T-2 and T-6 tolearn if they also can benefit from the Boot . Evaluationsof oxygen and energy consumption will be made tocompare metabolic efficiency of the Boot with longleg braces.

Implications—Data combined from the six original sitessuggest that the VRSLO is a viable means of achievinggait in the spinal cord injured . Several sites are interestedin quantifying energy requirements of the VRSLO whencompared to long leg braces and/or wheelchair propul-sion. The Boot is not a means of rapid propulsion, butbears certain aesthetic and functional advantages overprevious orthoses of similar intent . Therefore, it may bemore accepted (and utilized) by the SCI population.

Additionally, patients note subjective benefits ofstanding, such as reduced spasticity, better urinary andbowel elimination, and feelings of greater well-being.

This study has been recently expanded to includethree more sites and should continue to provide informa-tion over the next few years regarding not only theorthosis itself, but many related SCI topics as well .

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[379] Orthotic Stabilization of Thoracolumbar Injuries

Avinash G. Patwardhan, PhD ; Thomas Gavin, CO; Mark A. Lorenz, MD; Vijay Goel, PhD ; Mark Sartori, BS;Robert Havey, BSDepartment of Orthopaedics, Loyola University Medical Center, Maywood, IL 60153 ; Rehabilitation Research andDevelopment Center, Edward Hines, Jr . VA Hospital, Hines, IL 60141

Sponsor : VA Rehabilitation Research and Development Service (Project #A509-RA)

Purpose—Spinal orthoses have traditionally played animportant role in the early mobilization of patients withthoracolumbar injuries . However, the treatment protocolfor orthotic management of spinal fractures remains sub-jective due to a lack of objective data defining the three-dimensional (3-D) instability of spinal fractures and theextent to which different spinal orthoses can improve thebiomechanical stability of the injured spine . The objec-tive of this study is to evaluate the effectiveness of spinalorthoses in controlling the progression of deformities atthe injured segments under the action of different loadsand for different severity levels of injury.

Progress—To date, we have demonstrated the method-ology for a 3-point hyperextension orthosis . A finite ele-ment model (FEM) of the ligamentous spine with ribcagewas used . The model consisted of 17 beam elements;each beam element representing the overall contributionof all anatomical components of a spinal segment . Aninjury of increasing severity was simulated by progres-sively reducing the stiffness of T11-T12-L1 segments.Interaction of a 3-point hyperextension brace with thespine was simulated using experimentally measured stiff-ness properties of the brace. The model was used topredict displacements at the injured segment and loadsexerted by the orthosis on the trunk.

We are currently extending the above model to incor-porate the detailed anatomical structures of the thora-columbar region (Tll-L2) . This will allow us to simulatethe damage to individual anatomical componentsassociated with each type of injury, and thus, will facili-tate clinical interpretation of model results . This modelwill be developed using the commercially available pack-age, ANSI'S . The cortical shell and the cancellous coreof the vertebral body, and the posterior bony elementswill be modeled as 3-D isopararnetric 8-nodal brickelements . The annulus fibrosis will be modeled as a com-posite material consisting of fiber bands (lamellae)

embedded in the ground substance (3-D, isotropic8-nodal elements) around the nucleus . Nucleus materialwill be modeled as a 3-D incompressible fluid element.The ligaments will be modeled as bilinear cable elementssimilar to annular fibers . Material properties for thismodeling work will be derived from data in the literature.

We have also performed preliminary experimentalstudies to measure loads exerted by two types of hyperex-tension orthosis (Jewett and CASH) for different tasksusing normal subjects . The loads were measured usingthin arrays of Force Sensing Resistors sandwiched betweenthe orthosis pads and trunk . The different postures werequantified using the WATSMART motion measurementsystem. Electromyographic signals were also recordedfrom the erector spinae and rectus abdominus musclegroups using bilateral surface electrodes while subjectsperformed different tasks . Data from a total of three sub-jects have been acquired and are currently being analyzed.

Future Plans—This project will investigate the bio-mechanical stability of spinal fractures stabilized withdifferent spinal orthoses and surgical constructs, usedalone or in combination . The response of orthoticallysupported injured spine to loads in three planes, andevaluation of other orthotic designs such as the total con-tact thoracolumbosacral orthosis (TLSO) will be inves-tigated in the future . Further, experimental studies will beperformed to measure changes in orthotic loads as sub-jects perform various tasks . The long-term goal of thisstudy is to develop objective treatment guidelines toadequately protect patients with spinal trauma duringthe healing process of spinal injuries while preventingunnecessary surgery or bracing.

Recent Publications Resulting from This Research

Orthotic Stabilization of Thoracolumbar Injuries-A BiomechanicalAnalysis of the Jewett Hyperextension Orthosis . Patwardhan AGet al ., Spine 15(7) :654-661, 1990.

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[380a] Concerted Action Mobility Restoration for Paralyzed Persons(MORE Project)

Antonio Pedotti, ProfCentro di Bioingegneria, Politecnico di Milano, Milano 20148 Italy

Sponsor : Italian Ministry for University and Scientific Research, Italian National Research Council

Purpose—The Concerted Action MORE (MObilityREstoration for paralyzed persons) has been launched bythe COMAC BME (Committee for Management ofConcerted Actions in BioMedical Engineering) in theframework of the fourth Medical and Health ResearchProgramme of the Commission of the European Commu-nities . This 4-year program started in 1988 and involvesmore than 50 Institutes located throughout the countriesof the European communities . The Concerted Action isdirected toward those who are paralyzed as a result ofspinal injuries (i .e ., paraplegics, quadriplegics), cerebralpalsy, or neuromuscular diseases—people who representa high percentage of the physically disabled . However,many other disabled persons could also benefit from theresults of this action.

The objectives of MORE can be summarized asfollows:

• Stimulate research of new technologies having mean-ingful and beneficial application for disabled users,particularly in the areas of : 1) new electrode materials,implantable multichannel stimulators, control strate-gies and implantation techniques for walking restora-tion in paraplegics ; and, 2) new materials, ergonomicsand design, seating and support systems, and controlsystems for technical aids for independent mobility.

• Multi-center trials of existing devices and new tech-nologies and the exchange of evaluation results amongthe Centers involved in order to improve their valueand reliability.

• Coordination of methodologies and protocols for tech-nical, functional, and clinical evaluation of mobilityaids . Technical evaluation is concerned with the techni-cal quality and performance (e .g ., materials, durability,safety, reliability, etc.) of equipment ; functionalevaluation is concerned with the effectiveness of equip-ment in meeting the actual needs of its disabled user;clinical evaluation is concerned with the effects on theuser's health and compatibility with the body as itapplies to some devices implanted or directly inter-faced with the body (e .g ., FES equipment).

• Gathering of research and evaluation results anddissemination to industries and/or rehabilitation

professionals . For such purposes, a close relationshiphas been established with : 1) the ongoing Handynetproject—a section of the second program of Action inFavor of Disabled People (HELIOS) run by theCommission of the European Communities throughthe DGV, aimed at setting up a computerized informa-tion network concerned with the technical and socialresources for rehabilitation and social integration ; and,2) the CALIES program (Computer-Aided Locomotionby Implanted Electrical Stimulation) launched in theframework of the EUREKA program.

Progress —In the field of Walking Restoration (WREP),particular consideration was given to the following aspects:

• Investigation into the basic mechanisms governing thecontrol of normal gait (e .g ., kinematics, dynamics, etc .),and identification of the optimal control signals used forstimulating a minimum set of muscles in paraplegicpatients to restore walking in an acceptable manner. Thisstudy should lead to a general simulation approach forthe best choice of the control laws in individual patientsas a function of lesion, anthropometric characteristics,and eventual use of mechanical devices.

• Study of biocompatible materials, miniaturized hard-ware, and technical solutions for implantable systems,taking into account the problems raised by the wiring,connections, and implantable electrode interfaces.

• Study of the best electrical signals able to modulatemuscle force and fiber recruitment in such a way as tominimize muscle fatigue.

• Clinical trials and development of suitable protocolsfor training and adapting devices to the individualpatient.

In the field of Mobility Restoration, the followingactivities took place : participation in international meet-ings concerning the technical aspects of mobility andtransport for paralyzed persons ; the study and criticalcomparison of techniques and methodology for technicaland functional evaluation of wheelchairs ; and, investiga-tion into new materials and technologies for wheel-chair construction for achieving the best ergonomicperformance .

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Methodology/Results—In designing Concerted Action,we decided to concentrate specifically on the followingtopics on the basis of the present state of the market, thehighest priority needs of a large number of paralyzedpersons, and ongoing activities currently in progress inEurope: 1) Walking Restoration in Paraplegics (WREP),which includes mechanical devices, functional electricalstimulation (with implanted or surface electrodes),hybrid systems (combining mechanical devices andFES); and, 2) Technical Aids for Independent Mobility

(TAIM), which includes wheelchairs (manual and elec-tric), cars (adaptation, modification of controls, specialears), and transfer aids (hoists for personal transfer, stair-climbers, etc .).

Implications—Technical aids for mobility restorationassume great importance in achieving independencefor a better quality of life, social integration, accessto job opportunities, school integration, and socialrelationships.

[380b] Muscle Recruitment Optimization in Walking Restoration by FES

Maurizio Ferrarin, Dr Eng ; Antonio Pedotti, ProfCentro di Bioingegneria, Politecnico di Milano, Milano 20148 Italy

Sponsor : Italian Ministry for University and Scientific Research, Italian National Research Council

Purpose—The aim of this study is to develop properprocedures for choosing the best stimulation pattern forfunctional electrical stimulation (FES) in paraplegicpatients with the goal of restoring their ability to walk.

Progress/Methodology—We have developed, and imple-mented on a computer, a simulated model of a personwalking . The skeletal schematic had seven rigid links(three for each leg, one for head, arms, and trunk), andsix joints (two hips, two knees, and two ankles) . Thismodel solves the direct dynamic problem of starting frominitial conditions (position and velocity), when the timecourse of the segment positions is computed on the basisof mechanical torques applied to the joints.

To provide the necessary adaptability to an individualpatient, the body segments' anthropometric parameters(mass, length, inertial moment, and gravity center posi-tion) are estimated automatically, starting with the subject'sheight and weight . Under the hypothesis of symmetry,periodicity of gait has been considered the intervalbetween right and left heelstrike . The model is bidimen-sional, considering only movement in the sagittal plane.

The model is being tested with the time course ofjoint torques measured from healthy subjects, comparedwith measured kinematics of simulated ones . Startingfrom noncorrected kinematics, a trial and error proce-dure is used to correct the simulated kinematics modify-ing the input torques to obtain an optimal torque pattern .

Future Plans—A hybrid FES research program is beingplanned (in collaboration with clinical and rehabilitativegroups), for the restoration of walking in incompletespinal cord injured patients.

The model will be used as follows : 1) patient move-ment will be evaluated and the time course of the torqueexerted at the joints during walking will be computed tomeasure kinematics and ground reaction forces ; 2) com-puted torques will then be introduced as input for thesimulation model, and making use of a trial and errorprocedure in combination with optimization criteria, thebest muscle activation pattern will be derived ; and,3) this optimal pattern will then be applied to the patient,with the resulting kinematics evaluated with a quantita-tive analysis of the gait.

We also want to consider the "standing-up" move-ment and standing equilibrium with an adequate model,and study the relationship between stimulus and torquegenerated at the joint by induced muscular contraction.


Strategies in Muscle Recruitment for FES in Walking Restoration.Pedotti A, Ferrarin M, in Proceedings of the 11th AnnualConference of the IEEE Engineering in Medicine and BiologySociety, Seattle, WA, 1989.

A Modelling Approach to Stimulation Pattern Optimization.Ferrarin M, in Proceedings of the COMAC-BME Workshop"Restoration of Locomotion," Thessaloniki, Greece(in press) .

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[381] FES-Aided Paraplegic Gait Using a Controlled-Brake Orthosis

William K. Durfee, PhD; Robert Young, MD ; Allen Wiegner, PhDMassachusetts Institute of Technology, Department of Mechanical Engineering, Cambridge, MA 02139;VA Medical Center, West Roxbury, MA 02132

Sponsor : National Center for Research Resources, National Institutes of Health

Purpose—Restoration of gait to paraplegics using func-

matic, dynamic, and metabolic variables.tional electrical stimulation (FES) is a challengingproblem. A crucial difficulty is controlling the FES

Progress —Pilot studies based on stimulation of able-system for stability and smooth gait . One option for

bodied subjects to control the knee joint demonstrated theimproving control is to develop implanted systems with

utility of the controlled-brake approach . By combininglarge numbers of stimulation channels and complex con-

fine control of the brake with gross control of muscletrol algorithms. However, simple surface stimulation

stimulation, performance on position tracking tasks wasprograms should continue to be explored because they

greatly improved over both open- and closed-loop controlinvolve no surgery. One means of improving walking

schemes which used stimulation alone. We have com-function using surface stimulation is to add a mechanical

pleted a computer-controlled, 8-channel stimulator andorthosis in combination with FES .

have begun clinical experiments at the West Roxbury VABased on the preliminary work of our greap, we are

Medical Center using ambulating paraplegics . To date weproposing to address the problem of designing a func-

have implemented the standard 4-channel flexor with-tional FES-aided gait system using surface stimulation by

drawal FES-aided paraplegic gait in a single subject whoinvestigating a new device which may improve the quality

is T10 motor-complete.of gait . The device incorporates a knee orthosis containing a controllable friction brake at the joint . The purpose

Future Plans—Preliminary designs for a wearableof the brake is to shift the burden of control in a gait

version of a controlled-brake orthosis have been com-trajectory from controlling the stimulated muscles and

pleted . After further development, we will build a bracespastic reflexes to controlling the brake, a well-behaved

and test our hybrid gait assist concept in experimentsmechanical element. The controllable brake also pro-

using paraplegic subjects.vides a means of locking the knee joint during periods ofquiet standing, which may reduce overall muscle fatigue .


Further, the brake can provide a rigid brace mode whichmay be safer in the event of a stimulation failure.

To evaluate brake designs and performance, we willquantitatively test and compare the ability of SCIparaplegics to achieve FES-aided gait both with andwithout the brace . The assessment will include kine-

[382 Electrical Stimulation Strategy to Inhibit Spasticity During Gait

Jacqueline Csonka, BASe ; Morris Milner, PhD, PEng, CCE; Stephen Naumann, PhD, PEngHugh MacMillan Rehabilitation Centre, Toronto, Ontario M4G 1R8 Canada

Sponsor : Easter Seal Research Institute of Ontario

Open-Loop Position Control of the Knee Joint Using ElectricalStimulation of the Quadriceps and Hamstrings . Hausdorff J,Durfee W, Med Biol Eng Comp (in press).

Regulating Knee Joint Position by Combining Electrical Stimula-tion with a Controllable Friction Brake . Durfee W, Hausdorff J,Ann Biomed Eng (in press).

Purpose—Spasticity can be defined in terms of itscharacteristics, the most salient of which is an exagger-ated stretch reflex . Previous work has shown that it ispossible to inhibit the stretch reflex of triceps surae byelectrically stimulating the antagonist tibialis anteriormuscle. With recent evidence suggesting the influence of

the monosynaptic stretch reflex during gait, the aim ofthis project is to modify spastic gait by inhibiting thestretch reflex.

The project can be divided into two parts, each withits own specific goal . These goals are : 1) to determine therelationship between latency of stimulation, number of

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pulses in one stimulus burst, pulse frequency, andamount of inhibition ; and, 2) assuming that the stretchreflex of the triceps surae influences gait, to develop astimulation strategy during gait which would modulatetriceps surae tone.

Methodology—The study will involve subjects with mildspastic cerebral palsy. For the first part of the study,subjects will be seated in an Ankle Actuating Device, acomputer-controlled system which can impose rotarymovements about the ankle joint, causing a passivestretch of triceps surae . The tibialis anterior will bestimulated to inhibit the stretch reflex of triceps surae.Exploratory experiments will be performed to determinethe relationship between the number of pulses, the stimulus

frequency, the latency, and the amount of observed inhibi-tion. These results will allow us to determine electricalstimulus parameters that are efficacious in inhibiting thestretch reflex for use in the second part of the project.During gait, stimulation will be timed relative to depres-sion of a footswitch placed on the bottom of a subject'sfoot . Exploratory experiments will be performed todetermine the optimal latency relative to the footswitchdepression for each subject . Using the VICON and EMGsystems in the Gait Laboratory, an assessment of eachsubject's gait with and without stimulation will be made.

Progress—Equipment and software for both parts of theproject has been completed, and the first part of theproject has begun.

[383] Criticality of Fit of Ankle-Foot Orthoses

Johanne McKechnie, BSc ; Morris Milner, PhD, PEng, CCE ; Stephen Naumann, PhD, PEngThe Hugh MacMillan Rehabilitation Centre, Toronto, Ontario M4G 1R8 Canada

Sponsor : Natural Sciences and Engineering Research Council of Canada

PurposeThe purpose of this project is to determine thecritical parameters required for effective bracing of thelower limb with ankle-foot orthoses (AFOs) . Research onthe criticality of fit of AFOs will be conducted to inves-tigate the feasibility of a non-intimately fitting AFOs.AFOs being prescribed today are custom-made for eachchild, with the leg and foot fitting intimately into thebrace. It has been proposed that this intimate fit isrequired for the proper positioning of the foot to achieveoptimal ambulation, and to prevent pressure sores incases where the skin is insensitive . The fact that AFOsfit intimately creates several undesirable problems : ahigh production cost, a lengthy production time, and ashort usable period.

The remaining sections of the AFO are presumed toplay a much less important role . The points critical to thefit will be determined in this research . This project willlimit itself to investigating AFOs used to treat valgus footdeformity associated with spina bifida.

Methodology—A three-stage approach is planned : 1) amathematical model for the valgus foot deformity will bedefined . X-rays of valgus feet will be examined and cur-rent models of feet will be researched to aid in this task ;

2) the acceptable corrected foot position and allowabletolerances will be determined . Some subjective inputfrom orthotists and therapists will be required, togetherwith X-rays of foot position in currently used AFOs ; and,3)points where pressure must be applied to bring the footinto a corrected position will be determined . Static analy-sis will be used in conjunction with the previouslydefined model and corrected position.

The effectiveness of this bracing approach will beevaluated . An adjustable jig which will allow differentchildren to be tested will be built for this purpose . Withthe required corrective forces determined and evaluated,follow-up will include building functional AFOs based onthe derived information . The AFOs will be evaluated onthe children with respect to comfort and function.

Implications—Positive results will encourage furtherdesign work into a non-intimately fitting AFO. The out-come could be a less expensive AFO constructed in ashorter period of time and with a longer usable periodthan presently available AFOs . The procedures used inthis study could be extended to other foot deformitieswith the goal of obtaining corrective models and stan-dardized AFOs for the most common foot deformity .

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[384] QuickAttaching Brace for Improved Paraplegic Mobility

David Peifer, MD ; Andrew Schoenberg, PhDVA Medical Center, Salt Lake City, UT 84148 ; University of Utah Medical Center, Salt Lake City, UT 84132

Sponsor : VA Rehabilitation Research and Development Service (Project #B486-DA)

Purpose—The goal of this project is to develop a light-weight, full-leg brace with an electrically locking kneejoint. The major design requirements for this braceinclude the ability to : 1) hold 1300 in-lbs of torque arounda medial-lateral axis with a brake actuator force of lessthan 5 lbs ; 2) be locked or unlocked in less than 100 msin any angular position ; and, 3) be easily donned anddoffed in a few minutes by a paraplegic while sitting ina wheelchair . This brace is intended to be used in combi-nation with electrical stimulation of the leg muscles toallow paraplegics to stand and walk in areas inaccessibleby a wheelchair.

Progress/Results—The major effort during the last yearwas made in the development and testing of the knee-joint. A band brake design was used for its simplicity andhigh mechanical advantage . It consists of a 1.35-inchradius drum covered with neoprene rubber, and a stain-less steel band that is tightly wrapped around the drumwhen locked. The locking force of approximately 3 lbs issupplied by a spring attached to a lever. The brake isnormally locked, and is unlocked by pulling on a stringwound around a small motor shaft . To reduce weight atthe knee joint, the actuator motor is located at the hip.Testing of the latest design has shown that the desiredlocking torque of 1300 in-lbs is achieved with a springforce of 2 .5 lbs . The total lever arm movement requiredfor actuation is approximately 1 inch.

This actuation is achieved with a dc motor thatweighs 240 gm, and draws approximately 1 A of currentat 12 V during actuation . The motor is able to unlock the

brake in 40 ms . The mechanical design and developmentof the knee joint are reported in greater detail in a 1990master's thesis at the University of Utah.

Future Plans/Implications—During the remaining 6months of the current grant, we expect to integrate theRancho Los Amigos 8-channel stimulator, the actuatorelectronics, and the leg brace into a working unit, andperform preliminary durability bench testing of the totalsystem . Modifications to the brace and electronics will bemade as needed for a configuration that can be tested onhuman subjects.

The availability of a leg brace that is easily donnedand doffed, is lightweight, and is locked or unlocked byelectrical actuation would provide a basis of extendingambulatory function for many paraplegics who are nowlimited to wheelchair mobility . Such a brace may also seewider use . Prosthetists see the need for such a device inolder post-polio patients . In these cases, electrical stimu-lation of paralyzed muscles may not be needed . However,a brace of the weakened leg and knee that locks andunlocks during the gait cycle may significantly improvethe ambulation of this population.


Design of a Locking Knee Joint for Use with Hybrid FESSystems . Long J, Schoenberg AA, in Proceedings of the13th Annual RESNA Conference, Washington, DC, 375-376,1990.

A Locking Knee Joint Design for Use with a Hybrid FunctionalElectrical Stimulation System . Long J, Masters thesis, Universityof Utah, 1990.

[385] Comparative Study of 49 Walkers

John T. Ward, PhD ; Elaine Cremaldi ; Margaret A . Wylde, PhD ; Lee NorrgardInstitute for Technology Development, Oxford, MS 38655 ; American Association of Retired Persons, Washington, DC 20049

Sponsor : American Association of Retired Persons

Purpose—Forty-nine walkers provided by 20 manufac-

old, and 12 were over the age of 70 . Conditions leadingturers were tested by 19 walker users .

to walker use included arthritis, hip surgery, fractures,weakness, balance problems, amputation, and paralysis.

Methodology—All subjects are using or had used a walker

Subjects were asked to open and fold, and to lift eachin the past year. Seven of the subjects were 55 to 70 years

walker. They used the walker for assistance in sitting

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down and standing up. Each task was timed and subjectsestimated their effort level for performing the task . Addi-tionally, a physiograph was used to measure heart rate todetermine level of exertion while completing the tasks.

Each walker was used to traverse four different sur-faces . Subjects walked 50 feet each on a smooth indoorsurface, a thickly carpeted floor, and an outdoor lawn.Subjects also walked 40 feet up and down a 12-degreeramp. Subjects tested walkers while carrying a weightedload and held the walkers in a locked position.

Walkers were categorized by number of wheels . Thetraditional rigid and folding walkers have no wheels (the"no-wheel" group) . "Two-wheeled" walkers are struc-turally like the no-wheel walkers, but have a wheel oneach of the front legs . The newest walker design has awheel on each leg (the "4-wheel" group) . The 4-wheelwalkers vary the most in design, not only from the othertwo groups, but also within the 4-wheel group.

Results—The presence of wheels is the strongest pre-dictor of user performance . On all tested surfaces,4-wheel walkers outperformed 2-wheel walkers, which inturn outperformed no-wheel walkers . The reverse orderwas observed in opening and folding times, with themore complex 4-wheel walkers requiring the most effort.As an aid to sitting and standing, subjects gauged the

no-wheel and 2-wheel walkers more stable than the4-wheel walkers.

Among walkers with wheels, there was a stronginteraction between wheel size and type and walking sur-face. Small wheels tended to rattle and jam on unevensurfaces. Large wheels were harder to maneuver in tightspaces, but performed better than small wheels outdoors.Wheels with pivot mounts were easier to turn on allsurfaces than rigidly mounted wheels, but were perceivedby users as less controllable on uneven surfaces.

Walker height affected both user support and stabil-ity . A too-tall walker did not provide proper support;too-short walkers made the user uncomfortably stooped.Walker stability was a function of walker design, adjustedheight, and supported weight.

For no-wheel walkers, the greater the weight of thedevice, the poorer the subject's walking performance.

Future Plans—Grip location and orientation on most ofthe tested walkers violates the standard ergonomic designguidelines for handles . Most of the best-performingwalkers exhibited more than average rake on their frontlegs . Walkers with the base of the front legs or frontwheels extended well in front of the hand grip positionwere perceived as more stable and easier to turn . Furtherresearch on these two design aspects is warranted.

[386a] Free Knee Brace System

E.N. MienInstitute of Biomedical Engineering, University of New Brunswick, Fredericton, NB E3B 5A3 Canada

Sponsor : Canadian Paraplegic Association

Purpose—Individuals who have unstable knees mustoften resort to long leg braces for support . Walking withtwo long leg braces, without the ability to bend the knee,is clumsy and tiring. Our purpose, therefore, is todevelop a knee brace which can lock and unlock automat-ically to allow the user's knee to flex as sheltie walks.

Progress—The system we are building allows kneeflexion when the leg is unloaded and being swung ahead,and locks the knee when the limb is loaded . The brace,

which consists of long leg braces for each leg, and aclutch at each knee, has been designed as an electro-mechanical device . Switches under the foot sense whatpart of the foot is in contact with the floor, a circuit"decodes" the signal, and locks or unlocks the knees asrequired . A "wrap spring clutch" has been chosen as themost appropriate clutching mechanism, and suitableelectronics have been designed . A prototype brace hasbeen built for use in evaluation of the system by ourclinical collaborators .

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[386b] Comparison of Velocity and Position Control Strategies for the Case Western ReserveUniversity (CWRU) Upper Extremity ENS Orthosis

Brad Limpert, MASc ; Michael Joy, PhD; Morris Milner, PhD, PEng, CCE ; Joanne Bugaresti, MD, FRCP(C);Walter Literowich, BEEngT; Stephen Naumann, PhD, PEng; Henry O'Beirne, MA, MASc;Isaac Kurtz, MHSc, BASe, PEngThe Hugh MacMillan Rehabilitation Centre, Toronto, Ontario M4G 1R8 Canada

Sponsor : Canadian Paraplegic Association ; Natural Sciences and Engineering Research Council

Purpose—Our goals were to: 1) implement a velocitycontrol strategy on the Case Western Reserve University(CWRU) Micromini FNS orthosis ; 2) compare the effec-tiveness of velocity control with position control in theperformance of a functional task and a step-tracking task;and, 3) determine the effects of varying the gain anddead-space parameters for a velocity control strategy.

Methodology—The Micromini FNS orthosis wasdesigned to provide a C4-C7 quadriplegic person withsome limited hand function (i .e., a palmar grasp toprehend large or cylindrical objects, and a lateral graspto grasp small flat objects).

The CWRU strategy is position control, with handposition directly proportional to shoulder position . Eachcombination of hand position and force is achieved bymodulating the pulse widths of electrical signals stimulat-ing muscles in the hand and forearm.

An alternate strategy (velocity control) was devel-oped wherein the shoulder position determines the rateand direction of change of the output function . In thecenter of the range of motion is a dead-space, withinwhich a change in shoulder position does not affect theoutput function . Outside the dead-space, increasing pro-traction results in an increasing rate of hand closing whileretraction causes hand opening.

A computer-based system consisting of software,AID and D/A converters, and interface hardware wasdeveloped to evaluate position and velocity control strate-gies . Programs were also written to control low-levelA/D and D/A routines and to calibrate the joystick.

For the functional assessment, a book (10.5 x 3 x18 cm weighing 300 g) was moved from a midline resting

position on a table 79 cm high, to a book-holder on aseparate shelf.

For the computer simulation tests, a non-random,one-dimensional step-tracking task was used . Threetargets appeared on the screen . When a target was high-lighted, the participant moved his shoulder so that thecursor would enter the target . To successfully acquire atarget, the participant had to keep the cursor within thetarget for 0 .25 s . Fitts' constant (a normalized measure oftime) was used to measure performance and was calcu-lated from Fitts' law, that is, time to target = Fitts'constant x log 2 (2 X target distance)Iwidth.

Results—Position and velocity control were comparedfor reaching distances of 46 and 82 cm . At both dis-tances, the mean time with velocity control was less thanthe mean time with position control . For 46 cm distance,the mean difference was 2.14 s (n=4, p<0 .038), while at82 cm the difference was 24.3 s (n=4, p<0.16).

An additional assessment was performed todetermine if the addition of a dead-space to a veloc-ity control strategy improved performance on a reach-ing task.

Implications—Protraction and retraction of the shouldercan be used by C4 and C5 quadriplegics to controlvelocity or position of a hand or cursor on a computerscreen . Performance of velocity control is superior tothat of position control . This is probably because invelocity control, any hand position can be maintainedwhen the shoulder is relaxed . In position control,relaxing the shoulder causes the hand to return to itsinitial position .

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[387a] Further Development of a Protective Helmetfor Disabled Persons

Dieter Bochmann, CPO(C), FCBC ; Rod Moran, DDS, FRCS(C) ; Stephen Naumann, PhD, PEng; Steve Ryan, BESe, PEng;Greg Belbin, CO(C) ; Krista Holdsworth-Bordy, CO(C) ; Sandy RobinsonThe Hugh MacMillan Rehabilitation Centre, Toronto Ontario, M4G 1R8 Canada

Sponsor : National Health Research and Development Programme, Department of Health and Welfare, Canada; Cooper Canada

PurposeThe purpose of this project is to develop pro-

tective headwear which provides effective head and facialprotection for children who frequently fall . The specific

goals are to : 1) develop a second generation helmet which,

provides appropriate anatomical protection, is custom-fitted, comfortable to wear, looks attractive, and is

reasonably priced ; 2) evaluate the biomechanical perfor-mance of the helmet in the laboratory ; and, 3) assess thesubjective acceptance and performance of the helmetthrough clinical trials.

Progress/Methodology—Creation of the "secondgeneration" prototype has focused on the enhancementof its impact properties and structural integrity . Improve-ments in liner fit, ventilation, and hygiene are alsointended without compromising the helmet's generalcosmesis.

Initially, a preproduction helmet was designed forchildren with nominal head circumferences in the490-540 mm range (approximately 5-12 years of age).The prototype consists of a 3-piece, thermoformed Kydexshell—an anterior section, posterior section, and a chin

cup—with a full-contact polyethylene foam liner of uni-

form thickness . The assembled helmet is shaped to pro-vide both cranial and facial protection in the event of afall . Heat dissipation is promoted at the top of the helmetthrough convection channels in the liner.

To ensure a good anatomical fit on the head, thethree shell/liner parts are adjusted, located, and securedin place by an orthotist during the fitting . Furthercustomization of the helmet is possible through the addi-tion of liner inserts and trimming the helmet.

Both biomechanical and clinical testing of the proto-

type helmets were conducted to verify the concept . Whilethe biomechanical tests demonstrated performance con-sistent with effective cranial protection, feedback fromthe clinical trials indicated modifications which shouldbe incorporated into the production version of the helmetto enhance its serviceability.

Production tooling for modified ; rotomolded shellsand die-cut liners are being produced for both the smalland large size helmets . It is expected that these sizes willmeet the needs of most children between the ages of5 and 19.

Biomechanical tests and clinical trials using theproduction helmets have begun.

[387b] Evaluation of a Powered Orthotic Device forte Enhancementof Upper-Limb Movement

Robert Galway, BA, MD, FRCS(C) ; Stephen Naumann, PhD, PEng; Bill Sauter, CPO, FCBC(C);Josephine Somerville, BSc, MD, FRCS(C) ; Isaac Kurtz, BASc, MHSc, PEng ; Ihsan AI-Temen, PEng;Greg Bush, BA, DipO&P ; George McMillan; Chris O'Brien, BScOTThe Hugh MacMillan Rehabilitation Centre, Toronto, Ontario M4G 1R8 Canada

Sponsor : National Health Research and Development Programme, Department of Health and Welfare, Canada

Purpose—The objectives of this project are to : 1) deter-mine the benefits of a powered orthotic hand and elbowdeveloped at HMRC for people with severe upper limbweakness due to amyotrophic lateral sclerosis (ALS);and, 2) identify future enhancements to the poweredorthosis in order to further enhance the independence ofindividuals with ALS .

Progress/Methodology—The powered orthosis consistsof two spring-loaded ball-and-socket elbow joints, twosteel rods, a rigid rod corresponding to the ulna and atelescoping rod corresponding to the radius, and a handbrace with a single axis joint . The hand joint is openedand closed in a palmar grasp by a linear actuator, and theelbow is activated by the power winch unit . When the

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elbow joint is flexed, the forearm is partially supinateddue to the diagonally-applied force on the ulnar rod andthe extension of the telescoping radial rod.

Powered Linear Actuator. Housed in a slender alumi-num tube, the linear actuator is powered by a commer-cially available motor/gear box combination . Aone-quarter-inch ACME screw is attached directly to thegear-box output shaft and is supported by an anti-thrustball bearing to support axial loading in both directions.The screw engages with a nut located at the end of theorthosis to achieve the desired moment at the hand . Atthe end of the actuator, a swivel bracket is provided tomount the assembly onto the orthotic frame . The systemoperates on six volts, has a stroke of 1 .5 inches (whichis greater than other actuators) and is able to deliver aforce of 14 lb . Plans are underway to commercialize thelinear actuator through Variety Ability Systems Incorpo-rated (VASI).

Powered Winch Unit. The powered winch unit alsoutilizes a commercially available motor/gear box combi-nation. The motor is mounted to an aluminum housingand a shaft extension, integral with a worm, is attachedto the gear box output shaft . The shaft extension issupported by an anti-thrust ball bearing to support axialloading in both directions.

The worm engages with a worm wheel, which iscoaxially coupled to a small timing pulley. The worm

gear/pulley assembly is straddle-mounted in the alumi-num housing by two ball bearings . A timing belt isthreaded over the timing pulley and is secured by twofixed idler rollers located on each side of the pulley.

One end of the belt is attached to the housing, whilethe other end of the belt is attached to an appropriatepoint on the forearm. A limit switch triggered by the beltwhen the elbow is in full flexion, is provided as a safetyfeature . The unit is designed to be used interchangeablyfor the left or right arm of a powered orthosis user.

Myoelectric signals from the frontalis and procerusmuscles are being used for control of the elbow andhand. The left and right sides are used for flexion andextension respectively. The user contracts the muscles onboth sides of his forehead to switch between elbow andhand control.

Five individuals with ALS will be fitted with thepowered orthosis . The usage of these devices will bemonitored electronically with a miniature data-loggingdevice . Subjects will be asked to fill out a questionnaireto evaluate the usefulness of the device for various func-tional activities and the cosmetic appearance of the device.A therapist will assess the subjects' ability to type, eatand manipulate objects with and without the device.

Results—This study is in progress and no results can bereported at this time.

[388] Development of a Water-Resistant Covering for AFOsDuring Recreational Activities

Greg Belbin, CO(c) ; Mendal Slack, BSc(HK), CO(c)Hugh MacMillan Rehabilitation Centre, Toronto, Ontario M4G 1R8 Canada

Sponsor : Hugh MacMillan Rehabilitation Centre, Prosthetic/Orthotic Service Department

Purpose—The purpose of this research is to develop adurable and cosmetically appealing cover that providesprotection and support for asensitive limbs and ankle-footorthoses (AFOs) during recreational activities in andaround the water. Abrasions from concrete and sand candevelop into pressure sores, cause disuse of orthoses,restrict activities, increase deformity, and even necessi-tate surgical procedures.

Progress/Methodology—Five different prototypesunderwent various static and dynamic tests on two

subjects . The final prototype design is now being testedon several subjects and will be assessed for durability,ease of application, cosmesis, functional ambulation,water, and sand resistance.

Future Plans These covers will eventually become amarketable product available to all certified orthotists forfitting and dispensing .

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[389] Development of a Po ed Orthosis for Lower Limbs

Hiroyuki Miyamoto, MD ; Yasuhisa Sakurai, MD; Ikumasa Nakajima, MD ; Noriya Akamatsu, MD ; 'Weld Shimazaki;Kenji TokimuraDepartment of Computer Science, Chiba Institute of Technology, Chiba 275 Japan

Sponsor: Institute of Physical and Chemical Research, Agency of Science and Technology, Japanese Government

Purpose—In order to restore an appropriate gait pattern,a powered orthosis is being developed for paralyzed lowerlimbs that will support the patient's body and controllower limb movement . As a final goal, the poweredorthosis will enable paraplegic patients to walk on levelground with a variable cadence, to stand and sit, and togo up and down a staircase by appropriate command.

Progress—Considering the results obtained experimen-tally through preceding years, a second prototype wasdesigned and constructed . Its main purpose was to havea powered orthosis for lower limbs of an appropriate size,so that control methods explored in the past several yearscould be tested on paraplegic patients . The orthosis wasfabricated in carbon-fiber reinforced plastic (C-FRP),and in thigh and femur parts, and four electrohydraulicactuators were incorporated . These actuators now havedigital controls, in contrast with the first prototype whichused an analog type. Each actuator is controlled by asingle-board microprocessor, and all of these are totallycontrolled by a host microcomputer. Sensory systems suchas foot-switch sensors to detect plantar contact, opticalencoder to measure relative joint angle, and posture sensorto measure torso inclination in sagittal and frontal planesare used to accomplish a stable powered walk . The ortho-sis itself weighs 19.5 kg, and its control wagon 68 kg,which should be moved with the powered walk . A poweredorthosis will be realized using these two components .

Preliminary Results—After having checked the basicfunction of the powered orthosis on a normal subject, itwas tested on two paraplegics : both patients could walkwith this powered orthosis, grasping the rail of the wagonfor balance . This second version of the powered orthosishas sufficient torque for powered walk. After some modi-fications of the software program, one of the patientsrealized a powered walk at a cadence of 4 .5 second/step,while the former cadence was 6 .0 second/step.

Future Plans—Since the first tests on paraplegics havebeen successful, the control methods developed on thefirst prototype will be applied to the second prototype toimprove the function of the orthosis . As two orthoseshave been constructed which are identical except for geo-metrical size, all the control methods will be thoroughlytested on normal subjects prior to the clinical tests.

The interface between the patient and the poweredorthosis should be improved for practical use ofthis device.


Powered Orthosis for Lower Limbs . Miyamoto H, Ueda K, SanoA, Mori S, Nakajima I, Akamatsu N, Sakurai Y, in Proceedingsof the 11th Biomechanism Symposium (SOBIM Japan), 221-230,1989 (in Japanese).

Powered Orthosis for Lower Limbs . Miyamoto H, Sakurai Y,Nakajima I, Akamatsu N, in Proceedings of the 3rd French-Japanese Biomedical Technologies Symposium, 245-248, 1989.

[390] Development of a Practical, FES-Powered Walking Orthosisfor Paraplegics

M. Solomonow, PhD ; R .V. Baratta, PhD ; R. D'Ambrosia, MD ; P. Beaudette, RT(OP) ; N. Rightor, CO; W. Walker, COBioengineering Laboratory, Department of Orthopaedics, Louisiana State University Medical School, New Orleans, LA 70112

Sponsor : Louisiana Board of Regents (LEQSF Grant)

PurposeThe purpose of this study was to develop thefirst practical, commercially available walking orthosisfor paraplegics which could be used at home, withoutmedical supervision and assistance, and at realistic meta-bolic energy cost to allow prolonged function in standingup, sitting down, and walking on flat and inclined surfaces .

Progress/Preliminary Results—The Louisiana StateUniversity reciprocating gait orthosis (LSU-RGO) poweredwith electrical stimulation of the thigh muscles was fur-ther developed to allow independent standing and walkingon inclines at reduced energy cost . A large number ofpatients were fitted and followed up in the last 3 years .

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Energy Consumption of Paraplegics Ambulating with theReciprocating Gait Orthosis Powered with Electric Stimulation ofthe Thigh Muscles . Hirokawa S et al ., Arch Phys Med Rehabil71 :687-694, 1990.

[391] Functional Biomechanical Characterization andFunctional Design Specification : Orthotics

Dudley S. Childress, PhD ; Robert L . Van Vorhis ; M.D. Brncick; H.J . Krick; K. Mesplay; P.P. Peng; J.S. Rovick;V. Sanchez; J.W. SteegeNorthwestern University, Rehabilitation Engineering Program, Chicago, IL 60611Sponsor : National Institute on Disability and Rehabilitation Research

The RGO Generation II : Muscle Stimulation Powered Orthosis asa Practical Walking System for Thoracic Paraplegics.Solomonow M et al ., Orthopedics 12 :1309-1315, 1989.

Purpose—The objective of this project is to investigatethe potential of orthotic devices to control the position/motion of the bones . The function of an orthotic deviceis to control, limit, or stabilize the position or motion ofthe skeletal structure . However, the intervening soft tis-sues between the orthosis and the bones of the skeletalsystem complicate this task.

By investigating the potential of an orthotic device tocontrol the motion of the bones, we will determinebounds for the functional limitations and effectiveness ofsuch devices . The emphasis of this study is on the kneejoint and the potential for knee orthoses to control therelative motion of the femur and tibia.

Progress—The initial phase of this project examined thecurrent practice of orthotic management of the kneejoint. The intended function of knee orthoses may bebroken into three categories : 1) skeletal stabilization;2) motion restriction; and, 3) control of active motion.Skeletal stabilization devices, such as knee-ankle-footorthoses, are used by persons with functional deficiencieswho are unable to support their body weight on theirlegs . The success of a stabilizing orthosis is easy tojudge : evaluate whether the human functional deficit hasbeen compensated . The success of a motion restrictionorthosis or motion control orthosis is more difficult togauge and is the focus of this work .

A survey of orthoses for motion restriction and con-trol was made, and revealed that a single method ofattachment to the body is in common use : a proximal cufffor attachment to the thigh, a distal cuff for attachmentto the calf, and a pair of hinges connecting the two cuffstogether. The main difference between the motion controldevices and the motion restriction devices is that themotion restriction orthoses employ limit stops on thehinges and, since restriction orthoses are primarily usedpost-traumatically and post-surgically, they incorporatethick foam pads between the orthosis and the leg . Thesepads are thought to exacerbate the problem of controllingbone motion, and therefore, the more tractable problemof the motion control orthosis is analyzed first.

Orthotic cuffs interface to the limb along the lengthof the thigh and calf, but the greatest conformity of thecuff geometry to the limb geometry is in the region of theknee joint and the anterior tibia . Conformity in theseareas is intended to provide the best grip between theorthosis and the bone . However, due to the large degreeof motion at the knee, the underlying soft tissue struc-tures experience a high degree of spatial rearrangement(e .g ., skin folding) when the knee is flexed or extended,and there is some question as to whether the orthosis isgripping the bones or gripping the mobile soft tissue . Anexperiment has been designed and is now being used togauge the effects of tissue mobility around the knee joint .

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[392] MED Arm: A Six-Degree-of-Freedom Orthosis Simulatorfor Tremor Research

Michael J. Rosen, PhD ; Scott Maxwell ; Fletcher McDowell, MD; Mindy Aisen, MDNewman Laboratory for Biomechanics and Human Rehabilitation, Mechanical Engineering Department,Massachusetts Institute of Technology, Cambridge, MA 02139; Burke Rehabilitation Center, White Plains, NY 10605

Sponsor: National Institute on Disability and Rehabilitation Research ; Burke Rehabilitation Center

PurposeThe focus of this project is the design, fabrica-tion, and testing of a 6-degree-of-freedom (DOF)computer-controlled energy-dissipating manipulandumknown as the MED (Modulated Energy Dissipation)Arm . Its function is to serve as a test bed for assessmentof the effects of resistive loads on people disabled bymovement disorders during functional whole-arm move-ments . The device may be viewed as a human-interactiveorthosis-emulator which will allow experimental evaluationof the effectiveness of practical designs for tremor-suppression orthotics with a single laboratory facility. Itis also expected to serve as : 1) a tool for objectivemeasurement of tremors ; 2) a differential diagnosticsystem ; and, 3) a prototype compliant restraint system fortremor reduction in functional activities.

In its initial configuration, the MED Arm controls itsmagnetic particle brakes to behave as viscous dampers.Control of brake torque is open-loop, with the system'send-point 6-axis force/torque sensor serving only fordata acquisition . The "shoulder" and "elbow" joints ofthe Arm are linked mechanically, effectively providingone rotational joint, and one prismatic joint . As a resultof this, and the design of the three distal DOF, the forcesand torques produced by the brakes all operate through asingle end-point, and all act along and about respectiveorthogonal axes . It is this property that gives the systemits force-velocity colinearity.

Progress—Fabrication and bench testing of the MEDArm have now been completed . A number of objectivetests have been conducted to characterize the perfor-mance of the MED Arm . Results include the following:1) the brakes used for the distal three axes produce a max-imum force with which translations at the end-effectorcan be resisted of 14 lbf; 2) the measured maximumtranslational friction at the end-effector is 0 .25 lbf or lessdepending on direction ; 3) force-deflection characteristicsat the Arm end-point with the brakes at maximum currentto prevent slip showed a worst-case stiffness of 19 lbf/in ;

and, 4) the Arm is completely counterbalanced so that noweight is perceived, only inertia . The effective passiveinertia of the Arm at the end-point is 10 lbm or less,depending on the direction of applied force.

Methodology—The initial experimental protocol includedtwo components described as Abstract and Functional.All parts of both protocols were performed at four levelsof damping chosen to span the range of values providedby the Arm. In the Abstract tests, subjects were askedto observe a randomly moving target on a video screenand track it by movements of the Arm in a vertical planealigned with the screen . For the Functional testing, aprotocol was developed based on a standard clinicalrating system . Activities performed by the subjects"wearing" the Arm included nose-to-finger tests, hand-writing, Archimedes Spiral, water pouring, soup eating,and name-spelling on an expanded QWERTY keyboard.

Results—Preliminary human testing has been performedwith three subjects, two tremor-disabled and one able-bodied, to begin evaluation of the effects of using theArm . Data shows clear improvement with increaseddamping in the Functional test performance for both dis-abled subjects and a corresponding change in Abstracttest results for one of them.

Future Plans/Implications—Experiments of the typesdescribed above will continue with additional sub-jects . Additional development tasks will be undertaken,including revision of the control algorithms to pro-duce more sophisticated loading schemes. The effects ontremor of long-term use as a functional aid will alsobe measured.


A Modulated-Energy-Dissipation Manipulator and Application toSuppressing Human Arm Tremor. Maxwell S, PhD diss .,Massachusetts Institute of Technology, 1990 .

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[393a] Knee Flexion Alarm

Subrata Saha, PhD; Winn Johnson; J .A. Albright, MDDepartment of Orthopaedic Surgery, Louisiana State University Medical Center, Shreveport, LA 71130

Sponsor: National Science Foundation

Purpose—Diseases that affect the peripheral nervoussystem (e .g., cerebral palsy), may only affect sensoryfeedback pathways rather than the entire system . For chil-dren in this situation, an appropriate feedback device canassist in proper walking without constant observation byanother person . A student at the Caddo School forExceptional Children has such perceptual problems, inaddition to having very weak muscles . He often does notknow where his body is in space ; thus, he falls when hebends his knee beyond a certain angle . A knee flexionalarm device was designed for this student.

Methodology —The device requires two separate signals;one is a reference, the other corresponds to the flexionangle of the knee brace . By comparing the two signals,the device will signal the child when the proper conditionis not present . With a variable reference to the angle offlexion at which the device signals the child, gradualtraining can be performed wherein the child learns, at hisown rate, to maintain the proper knee position.

The circuit for such a device was built . The positiveinput is the reference voltage which can be set by adjust-ment of the 20 K-ohm potentiometer, each voltage corre-sponding to a particular angle . The negative input to theLM339 is connected to the 10 K-ohm potentiometer,which is mounted to a knee brace that the child wears.This voltage changes with the angle of the knee brace,which corresponds to the flexion angle of the child'sknee . The 10 K-ohm potentiometer is connected so thatas the flexion angle of the knee increases, so does the

voltage. Depending on the setting of the 20 K-ohm poten-tiometer, when the knee is flexed to an angle equal to orgreater than necessary, the output of the LM339 dropsenough to provide the required voltage across the piezo-electric buzzer to activate the buzzer, and the child hearsan audible sound signaling that the knee is flexed toomuch . A switch allows the device to be turned off whenneeded, and an LED with a current-limiter resistor indi-cates whether the device is on or off.

The 10 K-ohm potentiometer is mounted to the kneebrace . One part of the mounting holds the potentiometerand clamps to the upper part of the brace . The other partclamps to the shaft of the potentiometer and is strappedto the lower part of the brace . A cable runs from the poten-tiometer, terminating in a small box housing the circuitry,and worn on the child's belt . A belt clip mounted to thebox allows the device to be worn without inconvenienceor discomfort, yet allows for easy placement or removal.

ResultsWhenever the student using this device hears abeep from the black box attached to his belt, he remem-bers to straighten his knee . This has allowed him to bemore mobile and independent . The gait of this studentalso improved, because the alarm system helped him toincrease knee extension during stance phase and he haslearned to walk in a more erect fashion.

An electronic device has been built that, whenattached to the long leg brace of a handicapped personwith sensory deficit, provides an audio signal when theknees are in excessive flexion.

[393b] Upper Extremity Training Device

Subrata Saha, PhD; Winn Johnson ; J.A. Albright, MDDepartment of Orthopaedic Surgery, Louisiana State University Medical Center, Shreveport, LA 71130

Sponsor : National Science Foundation

Purpose—Some children confined to wheelchairs havedifficulty using crutches or a walker due to an inabilityto support their body weight with their arms. With propertraining, these children can learn to support themselveswith their arms and eventually learn to use crutches or awalker. This transition from wheelchair to crutches or a

walker can be very beneficial to the child, allowing himto become more mobile and independent.

The purpose of this project was to design and builda device to measure the amount of vertical force a childapplies while performing a shoulder depression motion.When the actual level of force being applied exceeds a

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desired level preset by the therapist, the child receivesreinforcement through the activation of a toy connected tothe device . The therapist can increase the desired leveluntil the child is able to apply enough vertical force tosupport his own body weight . After this goal is reached,the child can begin training in the use of crutches ora walker.

Methodology—The upper extremity training device con-sists of two force sensing plates (for the left and rightsides), a control box for the therapist, and two stagesof reinforcement.

Each force-sensing plate is constructed from one-quarter-inch aluminum tooling plate and contains a200-lb load cell (A.L. Design, Inc ., Model ALD-W-2) asthe force transducer. The output of the load cell is fedinto a three op-amp amplifier circuit . Two of the threeop-amps provide high input impedance into the amplifier,and the third op-amp provides differential amplificationof the two signals from the load cell . Since the voltageoutput of the load cell is proportional to the force beingapplied to it, an adjustable gain on the amplifier isrequired in order for the amplifier to maintain adequate

levels of output at low levels of input force . The ampli-fied output from the load cell is compared with thepotentiometer-controlled, desired-level set point usingan LM339 comparator chip . When the actual levelexceeds the desired level, the first stage of reinforcementis activated.

The first stage of reinforcement is simply an LED foreach side. When the actual level from the load cellexceeds the desired-level set point, the comparator outputgoes to a "low" state and the LED lights up . When theactual load level exceeds the desired level on both sides,the second stage of reinforcement occurs.

Progress—A prototype model has been built and ispresently being tested.

Future Plans/Implications—Actual use of this devicecannot begin at the Caddo School for Exceptional Childrenuntil the beginning of the new school year . However, dis-cussion with the physical therapist indicates that thisdevice will be beneficial in teaching these children tosupport their body weight with their arms and eventuallyuse a walker or crutches.

[394] CEDO: A Controlled-Energy-Dissipation Orthosis for Tremor Reductionin Activities of Daily Living

Michael J . Rosen, PhD ; Fletcher McDowell, MD ; Mindy Aisen, MD; Ivan Baiges ; Allison ArnoldNewman Laboratory for Biomechanics and Human Rehabilitation, Mechanical Engineering Department,Massachusetts Institute of Technology, Cambridge, MA 02139 ; Department of Spinal Cord Injury,Burke Rehabilitation Center, White Plains, NY 10605

Sponsor : National Science Foundation ; Burke Rehabilitation Center

Purpose—People disabled by large amplitude pathologicalintention tremor (e .g ., people who have multiple sclerosisor have had closed head injuries), are often incapable ofundertaking activities of daily living independently inspite of normal strength . As a means of selectivelysuppressing relatively rapid oscillatory movements andexposing voluntary activity, these investigators havedeveloped a 3-degree-of-freedom wheelchair-mountedcompliant orthosis which dissipates energy in afrequency-dependent way. It has the approximate geom-etry of a standard commercial mobile arm support ("ballbearing feeder"), but incorporates computer-controlledmagnetic particle brakes at each joint . The "elbow"brake is mounted on the support fixture and coupled tothe joint by a parallelogram linkage in order to make itunnecessary for the user to move its mass when using the

device . The brakes are controlled to behave as viscousdampers whose damping constant is adjusted as a func-tion of end-point position . Functional activities in a largepart of the normal seated range of motion are permitted.

Progress—Experiments have been conducted with eighttremor-disabled patients to determine the short-termeffectiveness of the CEDO in selective tremor reduction.These tests have included both simulated functionalactivities and objective tracking tasks . In virtually allcases, tremor was significantly reduced and signal-to-noise-ratio was improved (i .e., voluntary movement wasattenuated less than tremor, if at all) . Often, a value ofdamping was found between the extreme value and nonewhich appeared to offer the optimal effect . The bulk ofthese tests were conducted at the Burke Rehabilitation

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Center without on-site engineering involvement, indicat-ing the reliability and user-friendliness of the device.

Future Plans/Implications—Experiments will con-tinue, using the above protocol . In addition, tests oflonger-term effects will be conducted since the systemmay be viewed as a resistive exercise machine . Further,an investigation of the effect on user performance of thesystem's force-velocity noncolinearity will be conducted.(The device geometry does not produce resistive forcealigned with velocity at the user's arm for all end-point locations .)

Discussions are presently underway with an orthoticsmanufacturer with a view to licensing the design formarketing.


Development of a Whole-Arm Orthosis for Tremor Suppression.Baiges IJ, Rosen MI, in Proceedings of the 12th Annual RESNAConference, New Orleans, 290-291, 1989.

Patents

Whole-Arm Orthosis for Damping of Tremor. Michael J. Rosenand Ivan Baiges, MIT Docket Number : MIT-5229. Patentapplied for : June 25, 1990.

[395] Mobile Arm Support

P. Watson, BSc, PhD, AMIMechE, AASME ; R.G.H . Wallace, MCh(Orth), FRCSThe Rehabilitation Engineering Centre, Musgrave Park Hospital, Belfast BT9 7JB, N . Ireland

Sponsor : None listed

PurposeThis device provides a support for patients

Progress—The device has progressed from a labora-who have reduced arm control through neuromuscular

tory prototype to a production prototype and is beingweakness (particularly because of degenerative condi-

tested by patients at a local day-care center. Thetions like muscular dystrophy) .

units can be wheelchair-mounted or floor-mounted asa workstation.

Methodology—The patient's arm is supported in softslings above and below the elbow which allows for free

Preliminary Results—Patients who have used the armmovement in any direction—the volume of accessible

support show an almost immediate change in moodspace limited only by the patient . The patient's arm is

because of their new ability. Range of movement,weightless and therefore requires virtually no effort to

where any existed previously, seems to increase withinmove. The device can be adjusted to suit the arm weight

minutes.of each patient individually. The benefits are patientindependence and in the recreational and vocational

Future Plans—These devices will be produced inexpen-areas . The use of physiotherapy is also promoted .

sively by a local company.

[396] Lifting Seat

P. Watson, BSc, PhD, AMIMechE, AASME ; R.G.H. Wallace, MCh(Orth), FRCSThe Rehabilitation Engineering Centre, Musgrave Park Hospital, Belfast BT9 7JB, N . Ireland

Sponsor : None listed

Purpose—This device assists patients to move from aseated to a full standing position.

Methodology—The patient is supported on a seat basewhich remains horizontal until the standing position . Theseat armrests follow the movement, providing support

when the patient is upright, allowing easy transfer to awalking frame if needed.

The seat is raised using an airbag arranged in a novelway which reduces the pressure required and also keepsthe pressure in the bag almost constant throughout thelift . The airbag is inflated by a vacuum cleaner motor and

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could, o example, in a nursing home situation, beadapted to run from a compressed air system supplyingmany seats . The lift is entirely patient-controlled and canbe halted at any stage.

Progress—A production prototype is being developed.Variations in form will be examined (i .e ., a unit that canbe slotted into a wheelchair or an armchair), or built intoan armchair, etc .

Preliminary Results—The laboratory prototype couldraise an 85 kg man to afuUv standing position in approxi-mately 5 seconds . This can be adjusted so that the rate atwhich a frail or nervous patient rises is limited . Thepotential maximum lift in this configuration, with thepump supplying 2.5 psi, was 170 kg .

[377] adjusted versus unadjusted foot orthoses in the ... · va medical center, bronx, ny dr....

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