XII. Orthotics



Avinash G. Patwardhan, PhD; Thomas M. Gavin, CO; Robert M. Havey, BS
Hines VA Medical Center, Rehabilitation Research and Development Center, Hines, IL 60141; Loyola Medical Center, Department of Medicine, Maywood, IL 60153

Sponsor: Department of Veterans Affairs, VA Rehabilitation Research and Development Service, Washington, DC 20420
(Project #A865-RA)

PURPOSE--Spinal orthoses play an important role in the treatment of spinal injuries, low back pain, and spinal deformities. Whether or not a patient complies with the prescribed orthosis wearing hours is considered to greatly influence the clinical outcome of orthotic treatment. At the present time a reliable and objective method of measuring orthosis wearing-time is lacking. Current estimates are based on self-reported compliance and estimated wear and tear of the orthosis itself. As a result, there are no objective data to evaluate whether a correlation exists between the orthosis wearing-time and outcome of treatment for a given disorder. Further, there is no rational basis to determine the minimum number of wearing hours necessary to achieve good outcome for a given condition and type of orthosis.

  In the proposed study, we intend to refine the existing design of the compliance monitor that has been developed in our laboratory and assess its accuracy and reliability in measuring wearing-time for spinal orthoses under a variety of clinically relevant conditions.

METHODOLOGY--The study will be carried out in four stages. In the first stage we will refine the existing design of the compliance monitor that has been developed in our laboratory. This step will involve refinements in the current design of the data recorder unit and software. Next, we will assess the effects of temperature, humidity, and wear duration on the accuracy and reliability of the refined compliance monitor in the laboratory over a period of up to 3 months. Laboratory testing will allow us to precisely control (i) the temperature and humidity conditions with the use of an environmental chamber and (ii) the number of hours an orthosis is worn per day. The orthoses instrumented with compliance monitors will be tested on plaster casts under four environmental conditions and five wearing durations for up to 3 months. In the third stage, we will validate the ability of the compliance monitor to make accurate measurements of orthosis wearing time during activities of daily living using volunteer subjects. In the proposed study, 10 volunteers will be tested over a 1-week period, with up to 23 hours/day of orthosis wear time. Finally, we will evaluate the effect of long-term exposure to activities of daily living on the durability and accuracy of the compliance monitor. Twenty patients will participate in this phase of the study with informed consent. The patients will be tested for up to 3 months, thus providing long-term data on the performance of the device.

RESULTS--The software for the compliance monitor, transfer module, and IBM host computer has been developed and tested. The new compliance monitor prototype as well as the new design of the transfer module are undergoing final testing. All components for the construction of compliance monitors have been ordered and the layout of the final circuit board is currently under way. The FSR sensors have been ordered and a more reliable connection between the sensors and wires is being researched.

  Design of the environmental chambers is ongoing. All major components have been ordered, including the freezers, temperature controllers, temperature sensors, humidity sensors, and miscellaneous electronics. An enclosure for the signal conditioners and electronics is being designed. Recruitment of volunteers for device testing is ongoing.

FUTURE PLANS/IMPLICATIONS--Availability of an accurate and reliable technique to measure how long a patient wears a prescribed spinal orthosis will allow clinicians to objectively study the relationship between patient compliance and outcome of orthotic treatment, and arrive at rational guidelines for prescribing orthosis wearing hours.



David Armesto, MD; H. Richard Lehneis, PhD, CPO; Warren Frisina, BE
Lehneis Orthotics & Prosthetics Associates, Ltd., Roslyn, NY 11576; VA Medical Center, Brooklyn, NY 11209; VA Medical Center, Smithtown, NY 11787-3906

Sponsor: Department of Veterans Affairs, VA Rehabilitation Research and Development Service, Washington, DC 20420
(Pilot Project #A94-816PA)

PURPOSE--While other orthotics challenges might be addressed subsequently, the present intent is to improve the Spiral Ankle-Foot Orthosis, beset by materials problems since its inception decades ago.

METHODOLOGY--Methodology stems as much from organizational structure as from means of device development, featuring a government/private consortium based at the Brooklyn VA. Since a variety of promising new materials have been appearing on the market, it was anticipated that a search would be a fruitful complement to any theoretical efforts.

PROGRESS--While solid polypropylene has drawbacks for the Spiral application, it is unbreakable (a rare and central characteristic) given the pronounced bending it must undergo. Employing this characteristic as a foundation, means are being considered to moderate the undesirable features of this material for this application--that is, its dimensional instability when overheated (when it attains the consistency of chewing gum) which reduces workability during manufacture and subsequent correction.

  The first means considered to moderate the undesirable features of polypropylene was found in the marketplace, consisting of polypropylene reinforced with woven carbon fibers. Reportedly (though unpublished) Spirals have been constructed by other parties for patients. It was found that the material straight from the marketplace is "notch sensitive," tending to break if the surface is marred. This breakage has reportedly been offset by coating the completed device with another plastic material. We are following up on this approach to verify any validity. Although the high cost of such carbon-reinforced materials might not fulfill the stated economy criterion, polypropylene, in itself, does.

  The second means considered is to employ a prestressed form of polypropylene to reinforce the solid polypropylene. This is especially encouraging from the theoretical standpoint in that virtually the only material polypropylene will firmly bond to is itself. Thus, the matrix/reinforcement bond in this instance is more efficient that in any other composite employing a polypropylene matrix. Also, the constituents of the composite material are not overtrained.

PRELIMINARY RESULTS--While not biomechanically ideal, the above laminating procedure is being applied to patients. However, the procedure is cumbersome, and costly in terms of materials and effort. Therefore it is reserved principally for patients who have become accustomed to the Spiral Orthosis and will accept no substitute. Materials for the carbon/polypropylene approach are on order. Prestressed polypropylene/solid polypropylene samples have been produced. While only slightly stiffer than solid polypropylene, the composite remains dimensionally stable at working temperatures.

FUTURE PLANS--While we are not yet positioned to produce full scale Spiral blanks for patient fittings, efforts will be made in this direction. It was not anticipated that such promising materials would be adapted, in addition to being found, this soon.



Vern L. Houston, PhD, CPO; Carl P. Mason, MSBE; Martin Mussman, DPM; Edward J. Lorenze, MD; Kenneth P. LaBlanc, BS, CPO; MaryAnne Garbarini, MA, PT
VA Medical Center, New York, NY, 10010

Sponsor: Department of Veterans Affairs, VA Rehabilitation Research and Development Service, Washington, DC 20420
(Project #A674-2DA)

PURPOSE--The objective of this project is to develop a clinically effective and efficient computer-aided design and computer-aided manufacturing (CAD/CAM) system to quantify and automate the design and manufacture of well fitting, comfortable, and functional orthopedic footwear for US veteran pedorthic patients.

METHODOLOGY--To achieve this objective, the following research protocol has been established:

  1. Compile a computerized database of the medical/podiatric/pedorthic conditions and footwear prescriptions, digitized records of respective lasts and shoe patterns, (and when available, casts of the feet of patients), together with digitized records of the stock library lasts from which previous, custom orthopedic lasts were constructed, for a sample of 250 of the 10,000 pedorthic patients served by the NY VA Medical Center National Footwear Center (NFC);
  2. Analyze the data compiled in the project database to establish last, inlay, and shoe pattern quantitative design principles, deriving statistical averages and deviations for the most common types of modifications and design features, to establish and quantify NFC orthopedic footwear design and manufacturing requirements;
  3. Develop an intuitive, user-friendly, functional, clinically effective, and efficient pedorthic CAD/CAM system meeting NFC requirements;
  4. Conduct limited clinical tests to identify those areas/features of the pedorthic CAD/CAM system developed that are successful and those that require further research and development.

PROGRESS--So far, 289 subjects from the NFC pedorthic patient population have been sampled, their pertinent medical/podiatric/pedorthic information recorded in the project database, and their custom orthopedic shoe lasts, the stock library lasts from which they were derived, and their orthopedic shoe upper patterns have been optically digitized and compiled in the project database. The data have been analyzed to establish the most common types of medical/podiatric/pedorthic conditions and the respective footwear prescriptions and last/footwear modifications used in treatment thereof. Parametric statistical distributions of the last/footwear modifications identified have been compiled for use in establishing quantitative design and manufacturing specifications.

  From the specifications identified, a pedorthic CAD/CAM system has been developed. The system consists of the VA-Cyberware optical digitizer, the Tekscan F-Scan in shoe stress measurement system, the Vorum Research Lastfit;tm CAD last design system, the Gerber Garment Technologies FDS CAD shoe upper pattern design system, the VA CAM milling machine, and an Hewlett Packard Draft Pro pattern plotter/cutter. The constituent components have been interfaced and various enhancements introduced to comply with NFC design and manufacturing requirements. Additional adjunct software modules have also been developed enabling optical scan model variable reference center selection and realignment; last feature and regional boundary identification and registration; model surface grading, modification, and smoothing; and stress transducer calibration and data incorporation for insole design.

  CAM toolpath correction, clearance, and surface smoothing software for last manufacture has also been written and tested. Clinical trials with four control subjects and seven pedorthic patients have been successfully conducted using the pedorthic CAD/CAM system.

FUTURE PLANS--Refinement and enhancement of the project pedorthic CAD/CAM system shall continue. The results and the knowledge obtained in this project, together with results obtained by the investigators in their other research in tissue biomechanical characterization, measurement of static and dynamic loading, and foot/ankle biomechanics, shall be utilized to develop new, improved, biomechanically based orthopedic footwear designs.



Michael L. Boninger, MD; Charles J. Robinson, DSc, PE; Susan Whitney, PhD; Mark S. Redfern, PhD; Mark C. Musolino, BS
Department of Orthopaedic Surgery, Division of Physical Medicine and Rehabilitation University of Pittsburgh Medical Center, Pittsburgh, PA 15213-3221; Human Engineering Research Laboratories, VA Medical Center, Pittsburgh, PA 15206; Departments of Rehabilitation Science and Technology and of Physical Therapy, Schools of Health and Rehabilitation Science, University of Pittsburgh, Pittsburgh, PA 15261; Departments of Otolaryngology and Industrial Engineering, Schools of Engineering and Medicine, University of Pittsburgh, Pittsburgh, PA 15261

Sponsor: Department of Veterans Affairs, VA Rehabilitation Research and Development Service, Washington, DC 20420
(Project #A831-RA)

PURPOSE--Almost one-third of all ambulatory people over the age of 65 and not in nursing homes fall each year. Such falls are a major source of serious injury, morbidity, and mortality in the elderly population. Even in cases which do not cause injury, the fall itself may result in an increased sense of fear, less independence, curtailed activity, and a higher morbidity rate associated with inactivity. In previous studies, peripheral neuropathy, decreased proprioception, increased reaction time, and decreased strength have all been independently associated with an increased risk of falling. In addition, separate but related research has shown that taping the ankle can improve reaction time and strength in young athletic subjects with a history of ankle sprain. The aim of the present study is to determine the efficacy of two different ankle wrapping techniques as interventions to falling.

METHODOLOGY--A commercially available elastic ankle wrap and a common method of ankle taping were used on two different groups of elderly subjects: fallers (those who have fallen two or more times during the 6-month period prior to testing) and nonfallers. Subjects performed a series of tests that were designed to allow measurement of physical parameters that have been correlated to falling, including:

  1. amplitude and velocity of sway during quiet standing, with and without visual feedback
  2. amplitude and onset latency of muscle response to a rapid (standing) talar tilt
  3. amplitude and onset latency of muscle response to rapid (supine) dorsiflexion and plantarflexion
  4. proprioceptive response to slow (supine) dorsiflexion and plantarflexion
  5. torque generated across the ankle joint in response to rapid (supine) dorsiflexion and plantarflexion
  6. functional reach

  Measures of sway were made using a commercially available platform equipped with force transducers, designed to monitor center of pressure data. Muscle responses were measured for the gastroc, peroneus longus, anterior tibialis, and gluteus minimus muscles, and recorded through a series of four surface electrodes placed accordingly. The neuromuscular condition of the lower leg was evaluated for each subject prior to testing. Comparisons of the measured parameters were made among the ankle wrap, the tape, and a control group (no ankle support at all) to determine which of these wrapping techniques, if either, may act as an effective intervention to falling in the tested population.

PROGRESS--Twelve subjects have been tested to date. The protocol was modified after testing the first subject, and again after testing the second. As such, these two subjects were considered trial subjects, and have therefore been excluded from the main testing groups. Of the remaining 10 subjects, there are 3 fallers and 7 nonfallers; all were able to complete the entire testing procedure.

PRELIMINARY RESULTS--Tape was found to statistically decrease sway amplitude in nonfallers. Both the elastic-wrap orthosis and the taping technique showed clear trends toward improved values for the measured parameters as compared to control (no ankle support). In all cases, the tape, which is applied directly to the skin and therefore greatly enhances sensory feedback, was more effective than the elastic wrap. As the number of subjects tested increases, we expect to find that our interventions cause statistically significant improvement.

FUTURE PLANS--We plan to test 100 patients (75 fallers, 25 nonfallers); subject recruitment is ongoing. In addition to the experimental testing summarized above, a clinical trial of the commercially available orthosis is planned. We expect that the experimental and clinical data will provide information that will allow our group to design and test a low-cost orthosis that more closely mimics the effects of tape and thus has increased effectiveness in preventing falls.



Moshe Solomonow, PhD; Richard V. Baratta, PhD; Robert D. D'Ambrosia, MD
Bioengineering Laboratory, Department of Orthopaedic Surgery, Louisiana State University Medical Center, New Orleans, LA 70112

Sponsor: Medical Technologies, Inc. Grand Prairie, TX, 75050

PURPOSE--The effectiveness of the Bledsoe Pro-Shifter (BPS) brace designed for anterior cruciate ligament (ACL)-deficient patients was tested. Of the many knee braces available for this disability, the literature describes minimal or no effectiveness in alleviating the symptoms. The BPS was chosen for evaluation because it attempts to duplicate the lost function of the ACL by providing posteriorly directed force to the proximal tibia from 60° flexion to full extension.

METHODOLOGY--Twelve ACL-deficient subjects performed concentric isokinetic knee extensions at maximum effort both with and without the BPS brace. Electromyogram signals from the quadriceps, hamstrings, knee angle, and the extension force were recorded and evaluated to determine the effects of such dynamic bracing on muscle activity and joint stability.

RESULTS--High activity, or asymptomatic, subjects (n=5) experienced no change in muscle activity, but displayed a decrease in extension force throughout the active range of the brace. Low activity, or symptomatic, subjects (n=7) exhibited increased quadriceps activity and decreased hamstrings activity, and displayed a minor increase in force in the mid-range (80° to 40° flexion). These results indicate that dynamic bracing prevents quadriceps inhibition in symptomatic subjects by exerting a posteriorly directed force to the superior tibia; thus, the brace compensates externally for the absence of the ACL.



Dudley S. Childress, PhD; Laura Miller
Northwestern University, Prosthetics Research Laboratory, Chicago, Illinois 60611; email: d-childress@nwu.edu

Sponsor: National Institute on Disability and Rehabilitation Research, Washington, DC 22202

PURPOSE-- Crutches are often not used long-term because, with current designs, energy costs are very high. Therefore, many of those with significant lower limb impairment (e.g., those with spinal cord injury, spina bifida, post-polio, or cerebral palsy), often opt to use a wheelchair as the primary mode of transportation. It is hypothesized that crutch ambulation can be improved and made easier through the application and expansion of what is currently known about bipedal locomotion. Bipedal locomotion is presently several times more efficient than locomotion on crutches. The goal of this research to find out why this is so.

  Passive dynamic bipedal walking machines have been built that walk down shallow inclines with only the influence of gravity supplying energy. These machines look very similar to an individual using swing-through gait on crutches; the inner "legs" are coupled and the outer "legs" move together like the crutches. Both sets of legs end in rocker "feet." Since these passive devices can be built, there does not appear to be any reason why other ambulation styles (including crutch ambulation) cannot be performed with similar low energy requirements. The passive walking machines rely on rockers and the concept of the "virtual wheel." Some investigators of human gait hypothesize that the human body also uses some of these methods. The body has been described as "rolling" forward over various foot rockers during normal gait. Rockers have also been successful in restoring functional walking to some individuals suffering from multiple sclerosis by using rocker-soled shoes. Rockers are also used in orthotics. Rocker soled ankle-foot orthoses are often used to treat diabetics with foot ulcerations. Rocker crutches have been developed in the past. However, the design of the crutch has rarely been systematically addressed. It is hypothesized that the design (i.e., size and shape of the rocker) will have a profound effect on the efficacy of the crutch. This hypothesis is somewhat supported by the literature since some investigators have found improvement with rocker crutches while others have not.

METHODOLOGY--Initial designs are being developed for forearm crutches. The initial test subjects will be normal volunteers until the safety of the design is confirmed. Later designs will be tested on volunteers who use crutches and swing-through gait frequently. Using theoretical ideas and practical testing, the design of the crutch will be evaluated and modified.

PROGRESS--Currently, crutches are being designed and built in our laboratory to test the application of rockers to crutch ambulation. The initial designs include rocker bottom crutches with variable levels of spring as well as rocker units attached to the feet. This design is based on the theoretical considerations of the passive walking machines discussed. The goal is that, like the passive mechanical device, crutches can be developed requiring low energy so that the user can also "roll" with greatly reduced effort.

FUTURE PLANS--The ultimate goal is to develop theoretical principles upon which improved crutch designs can be based. The new design should allow users to ambulate farther and easier than with conventional crutches, offering alternatives to everyday wheelchair use. We are now beginning to coalesce the knowledge gained from projects on the effect of rocker shape on prosthetic ambulation, vertical compliance and spring, and floor clearance toward the development of new crutches.



Tariq Rahman, PhD; Rahamim Seliktar, PhD; Michael Alexander, MD; Rungun Ramanathan, MS
RERC on Rehabilitation Robotics, Applied Science and Engineering Laboratories, University of Delaware/A.I. duPont Institute, Wilmington, DE 19899; email: rahman@asel.udel.edu; seliktar@asel.udel.edu

Sponsor: National Institute on Disability and Rehabilitation Research, U.S. Department of Education, Washington, DC 20202; Nemours Foundation, A.I. duPont Institute, Wilmington, DE 19899

PURPOSE--This project is concerned with the development of an upper limb orthosis, intended primarily for individuals with muscular dystrophy. What characterizes this etiology is the progressive loss of muscle function where the distal musculature is the last to be affected. When a person retains sensory and partial muscular control, it is possible to augment his/her abilities with the aid of appropriate technology. This attitude is superior to a total substitution of his/her manipulative function with a robot. This project explores ways of doing this using powered orthoses that can support the arms against gravity and provide a broad range of arm movement.

METHODOLOGY--Our general assumption is that if some residual force is available and proprioception is unimpaired, then a powered orthosis can operate as an extender, by amplifying the residual strength of the person or by using signals obtained from other body sites. On the other hand, if there is little or no muscle function at all, then auxiliary signals, derived from other body sites or electrodes, can be used to drive the actuators, enhancing the person's strength. Residual hand function of potential users and the possibility of using supplementary end effectors will also be investigated.

  Work in progress has two phases running concurrently. The first is generating the information needed to specify the design criteria for a powered orthosis. The second phase will assess the functionality of possible designs and develop usable prototypes. In the first phase, the range motion of such a device is specified, by identifying and prioritizing the tasks that users wish to perform. In addition, methods of controlling such a devices are identified and further studied and developed to facilitate the design of a suitable mechanism. This investigation relates both to traditional design issues such as kinematics, power consumption, impedance, and also to the human interface issues such as the force that can be exerted by, and on, a person who would benefit from such a system. In the second phase, we shall develop a series of prototypes that will ultimately lead toward a marketable device. Consumers and their families are to be involved at all stages in this work.

PROGRESS--A series of prototypes has been designed and evaluated. Promising technologies include a novel mechanism for mechanically countering gravity, bowden cables to transfer forces to the base frame of the unit, and the utilization of nonlinear springs to control the effective impedance of a joint. Experiments are being carried out to find the lowest possible impedance parameters that the robot can present to the user while successfully following the his or her intentions while negating forces due to gravity.

RESULTS--A set of tasks desired by the target population has been identified. An active test-bed and several passive orthotic prototypes have been designed which enable the affected individual to place an arm anywhere in 3-D space within the limitations of the arm. Active and passive systems allow the orthosis to be moved with a minimal demand on his/her muscular system, although eventually the system must have the capacity for active control of the person's arm.

FUTURE PLANS/IMPLICATIONS--User evaluation will be carried out to verify the usefulness of the control schemes. This evaluation will yield answers to the sufficiency/insufficiency of one-sensor information. Future plans include making an anthropomorphic orthosis with gravity compensation and a robust control scheme which is intuitive to the user.




Donald McNeal, PhD; Samuel Landsberger, ScD; Richard Fite, CP; Carin Caves, BA; Vicente Vargas, BSME
Rehabilitation Engineering Program, Rancho Los Amigos Medical Center, Downey, CA 90242

Sponsor: National Institute on Disability and Rehabilitation Research, U.S. Department of Education, Washington, DC 20202

PURPOSE--The aim of this project is to design improved bracing for the myelomeningocele patient. Orthotic support for this population has always been difficult, but it is important for the physiological and social development of the child.

  Target goals for the new KAFO and AFO designs include stronger, lighter AFO shells with improved ankle joints and development of improved KAFO braces with easily-operated knee joints. An emphasis in this project, as in the other design projects, is to explore the use of advanced composite materials in novel ways to create orthoses that are lightweight, high-strength, low-profile, and aesthetically appealing.

PROGRESS--Clinical tests will assess the ankle articulation requirements of this patient group and help determine the appropriate selection of joint parameters, thus guiding development of future designs. Parameters to be investigated include amount of dorsiflexion assist, suitable range of motion, and the need for "soft-stop" limits. The design of an articulating ankle joint is underway, beginning with preliminary estimations of design parameters.

  Concerning the problem of a dorsi-assist, the first design concept was inspired by the simple, low profile design of the commercially available Oklahoma ankle joint. Dorsiflexion restoring force was added by incorporating into the unit a simple flexion spring (resembling the design of a popular type of Japanese clothespin). Another promising concept borrows from the design of anti-backlash gears with integral compression springs. Perhaps even more challenging than the design of an integral dorsi-assist is the incorporation of a strong, easily adjusted stop into the ankle joint without adding undue weight or size. Contact with manufacturers of commercial limited-range joints has been helpful in guiding the design process. These include joints manufactured by Pro-Com and USMC as well as a Becker Orthopedic ankle joint that came on the market in April 1996. It is possible that modifications to an existing design may produce a joint that meets our specifications.

  Progress has been made in developing a lightweight KAFO with the structural integrity to support larger, heavier children. The first prototype embodies an innovative single-upright design which smoothly blends uprights, knee joint and bands in an attractive shape. The design uses composite fibers in a manner which takes advantage of the unique properties of this material: it is moldable, very stiff, very light, and very strong. The bearing employed for the first prototype knee joint is lightweight, self-cleaning, and needs no lubrication, yet appears to be capable of withstanding the required radial and moment loads.



Jacquelin Perry, MD; Craig Newsam, MPT; Sreesha Rao, MS; JoAnne Gronley, MA; Jackie Heino, PT, MS
Pathokinesiology Laboratory, Rancho Los Amigos Medical Center, Downey, CA 90242

Sponsor: National Institute on Disability and Rehabilitation Research, U.S. Department of Education, Washington, DC 20202

PURPOSE--The purpose of this research is to determine the optimum orthotic system for the myelomeningocele (MMC) child and its carry-over to teenage patients. We seek to delineate the differences in gait requirements and performance of pediatric versus teenage patients (kinematics, kinetics, muscle control patterns); compare the available strengths and range of motion of the lower extremity muscles and joints of the two subject groups; and differentiate orthotic forces, foot stability, and biomechanics of two knee-ankle-foot orthoses (KAFO) and three ankle-foot orthoses (AFO).

METHODOLOGY--Children (4-7 yrs) and teenagers (12-17 yrs) with MMC lesions at the lumbar or sacral functional levels, who rely on KAFOs or AFOs to walk, will be recruited as subjects. Individuals using a KAFO will be randomly tested with standard and supracondylar orthoses. Individuals using an AFO will be randomly tested with three AFO designs: the solid polypropylene posterior shell, the posterior entry anterior shell (floor-reaction), and the dorsiflexion restraining articulating orthosis (Rancho design). Subjects will wear each brace for a minimum of 1 month prior to testing. Testing will include surface dynamic electromyography on five lower extremity muscles to record muscle activation patterns. Footswitches with compression closing sensors will be used to obtain foot-floor contact patterns and spatio-temporal gait characteristics. An EMED insole pressure measuring system will depict the pressure distribution on the sole of the foot during gait (also collected on nondisabled subjects for comparison). Kinematic data will be combined with ground reaction forces and anthropomorphic measurements to obtain three dimensional kinetics. These data will provide a measure of the joint demands in gait (moments and powers) using an inverse dynamics model (custom software). Energy cost will be measured with a modified Douglas bag system while the heart rate, respiratory rate, and cadence are recorded. Strength testing will be performed on the lower extremity muscles and range of motion measured for the lower extremity joints.

PROGRESS--Insole pressures have been collected for 10 nonimpaired subjects (5 children, 5 teens) to establish a normal database of foot pressures. Subjects are being recruited from area hospitals and outpatient clinics. The initial contact is for casting and fabrication of the first orthosis. A minimum of 1 month following receipt of the first test brace is required before testing.

FUTURE PLANS--Recruitment and testing of subjects will continue. Data analysis of the normative foot pressure data will proceed for publication and dissemination. From the data obtained in this study, a biomechanical model will be conceived to guide the design of more optimal orthoses to facilitate the patients' ability to walk and provide long-term foot protection.



Donald McNeal, PhD; David Eckhous, CO, OTR; Samuel Landsberger, ScD; Kevin Caves, BSME; Vicente Vargas, BSME
Rehabilitation Engineering Program, Rancho Los Amigos Medical Center, Downey, CA 90242

Sponsor: National Institute on Disability and Rehabilitation Research, U.S. Department of Education, Washington, DC 20202

PURPOSE--Mobile arm supports (MAS) are wheelchair-mounted devices which support the weight of the user's arm and provide assistance to shoulder and arm motions through a mechanical linkage. These units have enhanced function and independence of many individuals with flaccid paralysis or paresis of the shoulder and elbow flexor muscles. Problems with the current commercially available designs have greatly limited their use in spite of the benefits that they can potentially provide. These include complexity of setup, difficulty in adjustment, and lack of appropriate models for children. The primary objective of this project is to improve MAS design to address these deficiencies.

PROGRESS--The first objective of the project was to establish design specifications for a new MAS. To help develop meaningful design goals and desirable attributes, a survey questionnaire was developed for interviewing users of the MAS and members of their family. To date, 43 surveys have been completed and 7 users have had follow-up visits either at home or in the Rancho Los Amigos Medical Center, during which the users performed a range of motion exercises to enable assessment of device utility. Respondents were of both sexes, aged 4 to 60, and included both unilateral and bilateral users. Two types of MAS were represented: the "standard" model employing links hinged together with ball bearings, and a "radial" support employing one rotary and one sliding joint. We have identified a user's group that has consented to additional follow-up and prototype testing.

  The survey documented that over half the respondents feel they derive benefit from and continue to use their MAS for a variety of activities ranging from eating to typing to exercise. Seven users employ the device to help them pilot their power chairs. A desirable, but currently unavailable, feature of the MAS remains the incorporation of an easily engaged lock to secure the MAS during driving. Complaints included difficulty in adjusting the MAS to properly balance the arm, device bulk (especially in clearing doorways), and poor appearance.

  The survey results and direct observations of users provided valuable input to establishing design specifications. Design goals have been formulated emphasizing ease of adjustment, low profile, and attractive cosmesis, along with the requisite ease of motion. A useful option would be the ability to quickly relocate the MAS from the wheelchair to a preadjusted mount on a desk or table. New design concepts and prototype development have explored several different paths. A telescopic design of minimal rest size has been fabricated from aluminum tube and Delrin bearings. It is promising in concept, but will require good linear bearings to deliver sufficiently smooth performance under load. A multilink articulated unit has also shown promise. This prototype is made of stainless steel tubing and Delrin blocks in 4 in (18.16 cm) segments. The unit performs well under load and exhibits little vertical deflection. It is low profile, and will not interfere with passage through doorframes. The segmented unit was described by a patient as "friendly" in appearance, and indeed its shape is more organic in some sense than the rigid, right-angle machine-like alternatives. A novel wheelchair mount incorporates a 2-dimensional "bubble" for easy adjustment of gravity-free performance. A third design incorporates the wheelchair armrest as a base for mounting a movable support with smaller excursion radius. Prototypes of each design have been developed, and clinical evaluation using members of our user's group began in September 1996.



Stephen Naumann, PhD, PEng; Michael Lee, PhD; John Wedge, MD, FRCS(C); Greg Belbin, CO(C); Mercer Rang, MBBS, FRCS(C); Jonathan Kofman, MASc, PEng; Elizabeth Sheil, MASc; Henrique Costa, BASc; Branka Maric, MSc, PEng; Mendal Slack, BSc(HK), CO(C); Dennis Smith, DSc, PhD, FRSC; Steve Ryan, BESc, PEng
Bloorview MacMillan Rehabilitation Centre, Toronto; Toronto, Ontario, Canada M4G 1R8; Centre for Biomaterials, University of Toronto, Toronto; The Hospital for Sick Children, Toronto; email: ortcwf@oise.utoronto.ca

Sponsor: The Ontario Ministry of Health through the Ontario Rehabilitation Technology Consortium; The Hospital for Sick Children Foundation

PURPOSE--The current method of producing custom ankle-foot orthosis (AFOs) involves taking a negative plaster cast of the shank and foot, forming a plaster positive mold, and vacuum-forming a high-temperature thermoplastic sheet over the mold. This method is labor intensive, resulting in at least two client visits before orthosis delivery, and leads to high costs. The aim of this project is to develop a modular AFO that can be fitted in a single 2-3 hour visit at a lower cost than the present design. A material which can be formed as a prefabricated blank in the general form of an orthosis and custom formed directly on the client's limb will be developed.

PROGRESS--Most of our effort has been divided into two streams. The scientific stream has sought to understand how AFOs work, what kind of stresses they undergo, and why they fail. At the same time, hundreds of AFOs have been digitally encoded, resulting in an extensive database of relevant body measurements. The results of laboratory tests with instrumented AFOs worn by actual users have been combined with information gathered from computer modelling to generate an accurate picture of what happens in and to an AFO during everyday activities. The second stream, materials engineering, has been carried out in collaboration with Bloorview MacMillan for Biomaterials, University of Toronto, with the goal of developing a new material for custom AFOs that can be rapidly, inexpensively, and effectively dispensed to the end user. An innovative new composite has been developed and undergone extensive material properties testing.

  Testing and modification are now underway to ensure that the final product will be user-friendly and nontoxic. Ancillary activities include the construction of a sophisticated test protocol and apparatus for life-cycle testing of current and new prototype AFOs. Partnerships have been formed with a manufacturer and distributor, and they continue to advise on product development. Special consideration is also being given to alleviate some of the secondary concerns raised by consumers, such as heat build-up, incompatibility with shoes, and poor cosmesis inherent in current AFOs.

FUTURE PLANS--Upon successful completion of biocompatibility testing, the new AFOs will be clinically tested. Design and procedural changes will then be made before production and distribution are turned over to the corporate partners. Future work may include isolating other applications for the new composite and further functional improvements to AFOs.



Mukul Talaty, MS, BME; Rahamim Seliktar, PhD; Alberto Esquenazi, MD; Barbara Hirai
Biomedical Engineering and Science Institute, Drexel University, Philadelphia, PA 19104; MossRehab Hospital, Philadelphia, PA 19141; email: talatymc@duvm.ocs.drexel.edu

Sponsor: The Post Polio Clinic of the Albert Einstein Healthcare Network; the Calhoun Fellowship Endowment of Drexel University in Philadelphia, PA 19104

PURPOSE--Minimal progress in a continuing project to utilize EMG signals to assist in the orthotic alignment procedure has been made. Changes in muscle demands due to minor modifications to the range of motion in an articulated ankle foot orthosis has been measured in a Post Polio Syndrome population. Initial work showed that statistical analysis of integrated linear enveloped stride EMG signals from differing test conditions allowed comparison of muscle activity corresponding to these conditions. The initial and post-accommodation responses to new alignment conditions were assessed.

METHODOLOGY--Subjects walked in their own orthotics in several different range of motion restrictions. Surface EMG signals from tibialis anterior, soleus, rectus femoris, vastus medialis, vastus lateralis, and the long head of biceps femoris were recorded. Data were collected immediately after administering the change in range of motion to the orthosis and again after the subjects had used the orthosis in one of the new alignments for a period of one to several months. Linear enveloped and integrated stride EMG data from different conditions were statistically compared. Ensemble averaged profiles were also visually checked to eliminate spurious statistical significance.

PROGRESS--Additional Post Polio Syndrome subjects have been evaluated to assess whether neuromuscular deficiencies affect the trends found in nonimpaired subjects. For these subjects, heart rate, joint moments, and brace preferences were measured to corroborate statistical findings from EMG.

PRELIMINARY RESULTS--Muscle response was well defined and consistent in the Post Polio Syndrome subjects. The processing method used facilitated the statistical comparison which showed significant changes between test conditions. Statistical comparison of ensemble averaged EMG profiles indicated differences which were not readily obvious through the more clinically prevalent visual analysis. Furthermore, some common clinical heuristics, such as increasing ankle plantarflexion to relieve knee extensor muscles, were found to not always hold true. Although joint moment date was incomplete since subjects were not asked to target force plates, there was a modest correlation between the moment and EMG data. Trends in the EMG data suggested that the initial response to any new condition may be an extreme one where there was either maximal or minimal muscle activity.

FUTURE PLANS--Testing of additional subjects and developing a musculoskeletal model to predict the effect of orthotic range of motion constraints on muscle demands are pending.


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Last revised Wed 05/26/1999