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[212] COMPLIANCE MONITOR TO MEASURE PATIENT WEARING TIME FOR SPINAL ORTHOSES
Avinash G. Patwardhan, PhD; Thomas M. Gavin, CO; Robert
M. Havey, BS
Loyola University Chicago, Maywood, IL 60153; Hines VA
Hospital, Hines, IL 60141
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 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, we will refine the existing design of the compliance monitor that has been developed in our laboratory, paying particular attention to the 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 mo, precisely controlling the temperature and humidity conditions with the use of an environmental chamber and the number of hours an orthosis is worn per day. We will test the instrumented orthoses on plaster casts under four environmental conditions and five wearing durations. 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 (ADL) living using volunteer subjects. In the proposed study, 10 volunteers will be tested over a 1-wk period, with up to 23 hrs/day of orthosis wear time. Finally, we will evaluate the effect of long-term exposure to ADL on the durability and accuracy of the compliance monitor on 20 subjects for up to 3 mo, thus providing long-term data on the performance of the device.
PROGRESS--The software for the compliance monitor, transfer module, and host computer has been developed and tested. The new compliance monitor prototype as well as the new design of the transfer module underwent final testing, and 10 monitors were fabricated. Environmental chambers were designed and fabricated. Testing of an environmental chamber is underway. Testing for 10 volunteers is complete and data analysis is ongoing. The compliance monitor failed for three of the subjects, prompting a review of the software. One monitor failed due to programmer error, one failed due to a sensor wire interfering with a battery contact, and the third failed for unknown reasons. Investigation of the third failure is ongoing.
FUTURE PLANS/IMPLICATIONS--Subjects are currently being recruited for the final phase of the study, in which 10 will be prescribed part-time wear and 10 full-time wear. Availability of an accurate and reliable compliance monitor will allow clinicians to objectively study the relationship between compliance and outcome of orthotic treatment, and arrive at rational guidelines for prescribing orthosis wearing hours.
[213] ORTHOTICS DESIGN WITH ADVANCED MATERIALS AND METHODS: A PILOT STUDY
David G. Armesto, MD; H. Richard Lehneis, PhD, CPO;
Warren Frisina, BE
VA Medical Center, Brooklyn, NY 11209; Lehneis Orthotics
and Prosthetics Associates, Ltd, Roslyn, NY 11576;
Smithtown, NY 11787
Sponsor: Department of Veterans Affairs, VA
Rehabilitation Research and Development Service, Washington,
DC 20420
(Pilot Project #A1816-PA)
PURPOSE--While the Spiral Orthosis (SO)--intended not only to stabilize a totally flaccid ankle joint in all directions, but also to simulate all lost musculature below the knee in all phases of the gait cycle--was conceived and clinically applied decades ago, continual materials problems have kept this potentially widely applicable orthosis out of the orthotics mainstream. The focus at present is to resolve these materials problems; then it is intended to see that the orthosis takes its rightful place in that broad range between posterior leaf spring and solid ankle orthosis types.
METHODOLOGY--The SO consists essentially of a flat strip of semi-rigid material that is wound about the limb in spiral form, beginning at the bottom of the foot, extending medially, then about the Achilles tendon, continuing around the shank and terminating at the medial tibial flare, where it is locked into place with a calf band having a triangular cross-section transversely. This forms an exoskeleton that is believed to conform to the numerous articulations of the endoskeleton of the natural foot/ankle/shank complex, in that no appreciable movement of the orthosis relative to the limb is apparent during ambulation.
As the orthotic exoskeleton simulates the endoskeleton, all surrounding musculature--plantar/dorsi flexors, inverters/everters--is simulated by the continual loading and unloading of the orthosis during the gait cycle. Nevertheless, the device is by no means a panacea. It would not be preferred where there is excess spasticity and/or swelling, nor where more rigid support is required, nor where, for instance, the plantar flexors are normal.
PROGRESS--Since solid polypropylene has proven unbreakable for the SO application in clinical trials, the focus has been to ameliorate the poor workability of the material. When an SO "blank" (the orthosis in flat form) is heated sufficiently for moulding about the cast of a patient's limb, it must somehow be transferred from the oven and held to the positive cast with sufficient pressure for accurate conformance. Generally, the necessary degree of softness is inconsistent with transfer and holding forces, often resulting in thinned, weakened regions. Such hit-or-miss construction is not conducive to broad application.
To minimize this problem, the first intention was to cold form several layers of polypropylene cloth on the positive cast, then fuse the layers with heat. It was found, however, that no matter how securely the material was restrained, it underwent pronounced shrinkage. Although this approach proved unviable, it clearly demonstrated that stock polypropylene cloth is prestressed as a manufacturing byproduct.
A new line of experiments led to layups consisting of both solid and cloth polypropylene constituents that offset the tendency of cloth shrinkage, so that the entire composite becomes prestressed, and thereby able to resist the external forces required to work the material by the orthotist.
PRELIMINARY RESULTS--Since virtually the only material polypropylene will firmly bond to chemically is itself, the fused layups of solid and cloth polypropylene should effectively be a single piece of material not subject to delamination, either due to reheating by the orthotist during SO construction or to stress during ambulation. This, at any rate, is the working hypothesis.
To examine this hypothesis one subject with bilateral ankle deficit was fitted. On one limb a composite polypropylene SO as described was fitted to one limb, and an acrylic SO was fitted to the other for purposes of comparison, in that acrylic does not have the known high fatigue resistance of polypropylene.
Reportedly, the subject preferred the added support provided by the composite polypropylene, which was not surprising since the blank was laid up particularly for this rather heavy person, while the acrylic was from available stock.
Notably, composite polypropylene is stiffer per unit thickness than stock solid polypropylene. And stiffness can be adjusted by the number of cloth layers used and by employing the thickness adjustability of the mould employed during fusion of the composite blank.
FUTURE PLANS--Means must be found to improve the surface finish of SOs made from the polypropylene composite. Also workability needs improvement regarding the tendency of polypropylene to adhere when heated; since standard release agents can be discouraging, experiments are ongoing with various wrappings on the SO blank. When the materials questions have been resolved, it remains to integrate the SO into the orthotics mainstream.
[214] COMPUTER-AIDED DESIGN AND COMPUTER-AIDED MANUFACTURING OF ORTHOPEDIC FOOTWEAR
Vern L. Houston, PhD, CPO; Carl P. Mason, MSBE; Martin
Mussman, DPM; Gangming Luo, PhD; Kenneth P. LaBlanc, BS,
CPO; Mary Anne Garbarini, MA, PT; Cathy M. Cruise, MD;
Project Consultant, Hans R. Lehneis, PhD, CPO
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 computer-aided design and computer-aided manufacturing (CAD/CAM) system to effectively and efficiently design and manufacture well-fitting, comfortable, and functional custom orthopedic footwear for US veteran pedorthic patients.
METHODOLOGY--To achieve this objective, the following research protocol has been established:
PROGRESS--From the VA NFC pedorthic patient population, 289 subjects were sampled, their pertinent medical/podiatric/pedorthic information recorded, and their shoe lasts, the stock library lasts, and the upper patterns optically digitized and compiled in the project database. These data were analyzed to establish the range of medical/podiatric/pedorthic conditions and the respective footwear prescriptions, together with statistical averages and standard deviations for the last/footwear types and modifications used in treatment thereof. From the data compiled, specifications for a VA NFC pedorthic CAD/CAM system were established and a pedorthic CAD/CAM system developed.
Previous work on development of a pedorthic CAD system fulfilling these requirements was revised. Efforts were concentrated on development of an advanced dual monitor system based on the WindowsNT;tm platform, capable of simultaneous display of multiple views and different perspectives for ease of model visualization, evaluation, and modification. The system was augmented so that either an optically digitized scan of a patient's foot, or a set of VA-prescribed pedal measurements can be used as the system input. The input scan/measurements are used to automatically grade a style and model of last selected by the user to obtain the best fit possible from the system's predigitized, orthopedic last library. The system was expanded with digitization and storage of eight new orthopedic models in the system last library.
In addition to the usual CAD system design features, this system has design template and modification region linking to multiple landmarks with automatic regional scaling. It also has last feature and regional boundary identification and registration; variable reference center selection and realignment ability, including forefoot abduction and adduction; advanced spline model surface smoothing; menu selection for ease in application of common regional modifications (toe box expansion, bunion relief, metatarsal pad, scaphoid pad, medial and/or lateral wedges, etc.); input of Tekscan F-Scan (or equivalent system) pedal plantar stress measurements for last plantar surface and shoe insole design; uniform and variable plantar sole thickness selection for elevation control for leg length discrepancy compensation; etc. In addition, definitive 3-D last to 2-D shell flattening capabilities were incorporated, together with shoe upper pattern selection from the system library with automatic grading, piece definition, and design modification and styling capabilities.
CAM toolpath correction, clearance, and surface smoothing software for last manufacture was also written and tested, and the CAM milling machine was upgraded to permit carving of CAD lasts in high density polyethylene. Clinical trials with 4 control subjects and 10 pedorthic patients have been successfully conducted to date using this system.
FUTURE PLANS--Refinement and enhancement of the 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.
[215] CLINICAL TRIAL OF FOOTWEAR IN PATIENTS WITH DIABETES
Gayle E. Reiber, MPH, PhD; Douglas G. Smith, MD
VA Puget Sound Health Care System, Seattle, WA 98108;
Department of Orthopedic Surgery, University of Washington,
Seattle, WA 98185; email: greiber@u.washington.edu;
gsmith@u.washington.edu
Sponsor: Department of Veterans Affairs, VA
Rehabilitation Research and Development Service, Washington,
DC 20420
(Project #A832-2RA); National Institute of Health, NIDDR,
Washington, DC; Centers for Disease Control and Prevention,
Atlanta, GA
PURPOSE--Lower limb ulcers precede about 85 percent of diabetic amputations. Nearly half of the events that begin the causal pathway leading to ulcers and amputation are footwear related. Yet the efficiency of footwear in preventing ulcers and amputations in the high-risk diabetic population has received limited experimental investigation. Randomized trials have not assessed the combined contribution of therapeutic shoes and different types of insoles on foot ulcer prevention while also addressing patient footwear adherence.
This study is designed to determine the extent to which study shoes and study insoles will reduce incidence of reulceration in diabetic individuals with a prior history of foot ulcer, and to estimate costs of ulcer prevention using these strategies.
METHODOLOGY--Diabetic patients with a prior healed foot ulcer are being randomized to study shoes and insoles or their own footwear. Patients will be followed for 2 yrs to determine the incidence of reulceration.
PROGRESS--Patients are currently being recruited and randomized to the trial.
FUTURE PLANS--We shall continue enrollment, data collection, and monitoring. This trial will assess the potential for savings in morbidity and provide information on potential cost savings that could be achieved in the VA with footwear interventions.
[216] THE ROLE OF ORTHOTIC INTERVENTION IN RESOLUTION OF PLANTAR FASCIITIS
Alberto Esquenazi, MD; Mukul Talaty, MS, BME; Barbara
Hirai
Gait and Motion Analysis Laboratory, MossRehab Hospital,
Philadelphia, PA 19141;
email: aesquena@aehn2.einstein.edu
Sponsor: Department of the Army; Post Polio Clinic of the Albert Einstein Healthcare Network
PURPOSE--A major goal is to determine the effect of short leg braces and shoe inserts on the pattern of muscle use and resolution of symptoms in individuals with plantar fasciitis. In addition, it is desired to determine whether the change in muscle use patterns may be indicative of resolution of the overuse symptoms. This may facilitate inferences on effective treatment options.
METHODOLOGY--Subjects from two groups with clinically documented plantar fasciitis have completed the protocol to date. Group 1 are subjects with Post Polio Syndrome (PPS) and Group 2 are controls with no known neurological, orthopaedic, or other disorders which may affect muscle use patterns during gait. Each subject is fitted with a custom orthotic (short leg MAFO for the PPS subjects, in-shoe orthotic for the controls). Plantar fasciitis symptom severity is recorded using a visual analog scale at the initial visit. After 1 wk of orthotic use, subjects are evaluated in the Gait Lab. EMG of soleus, tibialis anterior, quadriceps, and the biceps femoris of the hamstrings group are recorded, as are motion and joint moments of the lower limbs and walking speed. The above data are recorded both with and without the orthosis; order of testing is randomized. At the final visit, approximately 1 mo later, the severity of the plantar fasciitis symptoms is again recorded.
PROGRESS--This is the first year of the study; testing is ongoing, and 20 subjects have been seen to date. Data analysis is being undertaken to determine trends.
PRELIMINARY RESULTS--Differences have been found in kinematic data as well as in EMG recordings in conditions when walking with the orthosis as compared to walking without the orthosis. Ensemble averaged kinematic profiles and EMG profiles clearly indicate differences in patterns with and without the orthosis. An insufficient amount of data has been analyzed so far to be able to speculate about correlation between resolution of symptoms and changes in muscle use patterns as well as in trends in the methods of compensation.
FUTURE PLANS--It is desired to test an additional 20 subjects to establish a sample large enough for statistical significance. Trends in how gait parameters are affected in the PPS population as compared to the controls will also be analyzed. In general, trends in compensation to the orthosis will also be monitored as part of an ongoing effort to document and model compensation mechanisms.
[217] MEDICAL EVALUATION OF 70 PARAPLEGICS USING A PRACTICAL FES WALKING ORTHOSIS
Moshe Solomonow, PhD; E. Reisin, MD; E. Aguilar, PharMD;
Richard V. Baratta, PhD; R. Best, BS; Robert D'Ambrosia,
MD
Department of Orthopaedics, School of Medicine in New
Orleans, Louisiana State University Medical Center, New
Orleans, LA 70112
Sponsor: Louisiana Board of Regents, Baton Rouge, Louisiana 70804
PURPOSE--The objective of this evaluation research was to determine whether a well-designed hybrid system based on mechanical and electrical muscle stimulation principles can be applied to the majority of the paraplegics applying for rehabilitation of walking functions; whether such a walking system can be successfully accepted by a large number of patients; and whether persons who accept such an orthosis and use it regularly can receive significant health benefits.
METHODOLOGY--Seventy persons aged 18 to 65, with paraplegia ranging in injury level from C-5/6 to T-12, with a wide range of spasticity and contractures of the leg muscles and joints, were accepted to the program and fitted with the Louisiana State University (LSU) Reciprocating Gait Orthosis (RGO), powered with a portable electrical stimulator to activate the leg muscles. Patients were trained to stand up, walk at least 180 m, walk on grass, ramps, and curbs, and to sit down as well as don and doff the orthosis. Blood, urine, echocardiogram, and spasticity tests were given to each subject at the beginning and end of the program.
RESULTS--It was shown that 75.7 percent of the subjects could successfully use the orthosis without requiring any assistance from others for the prescribed tasks. The medical tests demonstrated that with the minimal use of the walking orthosis for 3 hrs a week, a significant reduction of cholesterol, spasticity hydroxyproline, and calcium was noticed, together with improvements in heart and lung functions.
IMPLICATIONS--The LSU-RGO, powered with muscle stimulation, demonstrated that it is a practical walking orthosis for persons with paraplegia, being accepted by 76 percent of the subjects while improving bone, ligament, and cartilage conditions, together with reducing spasticity and cholesterol. Improvement in heart and lung functions further assert the benefit of using such orthosis.
[218] CRUTCH AMBULATION
Dudley S. Childress, PhD; Laura A. Miller
Northwestern University Rehabilitation Engineering
Research Program, Chicago, IL 60611; email:
d-childress@nwu.edu;
Web: http://www.repoc.nwu.edu/
Sponsor: National Institute on Disability and Rehabilitation Research, U.S. Department of Education, Washington, DC 22202
PURPOSE--Crutch ambulation is extremely inefficient compared to normal upright bipedal locomotion. Crutch users are slow and take small steps. Even at this slow velocity, ground reaction forces are higher than for normal walking. Models of human ambulation have been proposed in which walking is described as a passive process (i.e., a system that requires no energy input). Many of these models are based on the inverted pendulum, with the idea that energy is transferred back and forth between its kinetic and potential forms during the gait cycle. Physical models have also been built that can walk with little energy input. By taking advantage of the inverted pendulum and rocker-shaped feet, the model can roll with little effort. These models are very similar in appearance to swing-through crutch ambulation. Both have four legs, with the inner two coupled and the outer two coupled. Also like the model, the crutches (and often immobilized legs) are passive systems.
METHODOLOGY--Crutches are not often used, because with the current designs energy costs are much higher than for normal walking or wheelchair locomotion. 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. Since passive bipedal devices can be built, there do not appear to be any mechanical reasons why crutch ambulation efficiency cannot be increased, by new crutch design concepts, training, and new locomotion techniques.
PROGRESS--Initial data have been collected using a prototype of a modified crutch design based on passive dynamic walking machine models. Rockers were added to the terminal end of elbow crutches and to ankle-foot orthoses. One subject was used for the initial testing. Three-dimensional kinematic data and force plate data was collected for trials of swing-through gait using normal crutches and modified rocker crutches. Normal walking trials were also collected.
RESULTS--Comparison between the data of normal ambulation and swing-through crutch gait with standard crutches shows that there is considerable room for improvement. The most obvious variations were the reduced speed, the increase in the peak vertical ground reaction force, and the large fluctuations in the horizontal forward velocity. As a general observation, none of the curves associated with crutch ambulation had the smooth symmetric patterns typical of normal ambulation. The modified crutches did positively alter ambulation parameters; for example, timing was more symmetric between the body and crutch stance.
FUTURE PLANS--Analytical models are being developed to investigate swing-through crutch ambulation. These models will address parameter variation including characteristics of the rocker radius and position and addition of compliant spring mechanisms for shock absorption and energy storage. Unlike the previous models in which the inner and outer leg couples are identical, the size and mass distribution of the crutches (outer) and body (inner) for the crutch user are not symmetric; therefore, the model will also be used to assess the use of asymmetric parameter selection for each link couple. The results of the model are expected to improve the speed and reduce the large fluctuations in the velocity as well as the large peak vertical ground reaction forces and thereby improve the efficiency of swing-through crutch gait.
[219] MEASUREMENT OF PLANTAR FOOT SOFT TISSUE PROPERTIES OF PERSONS WITH DIABETIC NEUROPATHY FOR PREDICTION OF PLANTAR FOOT PRESSURES AND ASSESSMENT OF PLANTAR ULCERATION RISK
Sheldon R. Simon, MD; Necip Berme, PhD; Cenk Guler;
Elena Oggero
The Division of Orthopaedics and the Department of
Mechanical Engineering, The Ohio State University, Columbus,
OH 43210; email: Simon.1@osu.edu;
Berme.1@osu.edu
Sponsor: National Institute for Disability and Rehabilitation Research, Rehabilitation Engineering Research, Washington, DC 22202
PURPOSE--For people who suffer from diabetes, especially those complicated by neuropathy, foot problems can be a common phenomenon. One of the more common is plantar ulceration that can range from small superficial ulcers to deep penetrating ulcers with bony involvement. A common occurrence and necessary prerequisite for ulceration is elevated plantar pressure. Investigators as well have shown correlations between ulcer formations and sites of high pressure and/or loading. Shoe orthotics have been shown to be effective in the reduction of pressures. A new type of orthotic involves a plastic insole filled with silicone gel. Our goal has been to test this orthosis for its effectiveness in reducing plantar pressure.
METHODOLOGY--An important issue in dealing with the experimental determination of pressure distribution between the foot and an orthosis is that the pressure measuring mat introduces another layer under the sole, which in itself may modify the pressure distribution. Therefore, we carried out tests with and without shoes. Further to this approach, current research also targets increasing our understanding of the effectiveness of experimental techniques in these types of investigations by modeling the plantar soft tissues and being able to predict pressure distributions from soft tissue geometry and mechanical properties.
PROGRESS--A viscoelastic sphere model with realistic properties, which can be used to represent the plantar surface of the foot during locomotion, was developed. The mechanical properties of the sphere were identified using experimental data on heel pads. To validate the model, the results of the experimental study were reproduced by simulating the impact tests. Sensitivity analyses of the model parameters were carried out. The model was found to be insensitive to variations both in stiffness and damping properties. The change in the thickness of the soft tissue, however, affected the maximum force of deformation, proportionally. A symmetrical pressure distribution for the sphere during impact was calculated. It was concluded that this device can be incorporated into a model representing the plantar surface of the foot.
RESULTS--The modeling approach presented here is not limited by the utilization of spherical bodies: the same approach can be applied to any irregularly shaped surface as long as the geometry of the soft tissue is available in some form. This will allow for higher models, using multiple overlapping spheres, to create a complex geometry, such as a more physiological model of the foot.
FUTURE PLANS--We intend to investigate a more physiological model of the foot for application in the study of the diabetic foot: using a similar approach, recreating the geometry of bones and tissues for calculating the maximum applied forces and pressure distribution under the foot. This is even more attractive, considering the possibility of adding the effect of shoe insole as another spring-damper system in series with the foot model to be able to compare the model results with previously acquired patient data and eventually give some indication about the mechanics of foot ulceration in persons with diabetes.
[220] ORTHOTICS FOR MYELOMENINGOCELE PATIENTS, TEENAGE VERSUS CHILDHOOD
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 of Disability and Rehabilitation Research, U.S. Department of Education, Washington, DC 22202
PURPOSE--The purpose of this research is to determine the optimum orthotic system for the myelomeningocele (MMC) child and its carry-over to teenagers. There are three specific goals of this research: 1) to delineate the differences in gait requirements and performance of pediatric versus teenage patients. 2) to compare the available strengths and range of motion of the two subject groups. 3) to differentiate orthotic forces, foot stability, and biomechanics of two knee-ankle-foot orthoses (KAFOs) and three ankle-foot orthoses (AFOs).
METHODOLOGY--Children (4-7 years) and teenagers (12-17 years) with MMC lesions (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: 1) solid polypropylene posterior shell, 2) posterior entry anterior shell (floor-reaction), and 3) dorsiflexion restraining articulating orthosis (Rancho design). Subjects will wear each brace for a minimum of 1 mo prior to testing.
PROGRESS--EMED insole pressures have been collected for 10 controls (5 children, 5 teens) to establish a normal database of foot pressures. Currently, 11 subjects (4 children, 7 teens) have been admitted into the study and 6 have completed all testing.
RESULTS--Subject characteristics for one teen (S1) and one child (S2) who use AFOs are described. Both subjects are community ambulators who are able to walk without assistive devices. Stride characteristics for both subjects reflect velocity greatest for the anterior shell, slowest for the posterior shell. For both subjects, the greater velocity achieved during ambulation in the anterior shell brace was the result of increases in both stride length and cadence in comparison to the posterior and articulating braces.
All three braces are designed to control ankle dorsiflexion (DF) in terminal stance, allowing the user to achieve heel off and a subsequent increase in stride length. For both subjects, peak DF in terminal stance was greater than normal for all 3 braces. Additionally, peak DF was delayed by 3 to 8 percent of the gait cycle (GC) in each of these AFOs. The least restraint of stance DF occurred with the articulating brace design. For S1, the posterior shell brace provided the greatest restraint of DF; however, a corresponding earlier heel off and increased stride length was not recorded. For S2, the anterior shell best limited DF and resulted in only a slightly delayed heel off (38 percent GC vs. 30 percent normal). For both subjects, the anterior shell brace provided the earliest peak dorsiflexion (S1 at 50 percent GC; S2 at 49 percent GC) and resulted in the longest stride length of the three braces.
Knee motion was similar in strategy across braces for the two subjects, but different between subjects. S1 tended to have excessive knee extension throughout the stance phase, exhibiting a period of instability in loading response, characterized by extension followed by flexion. S2 tended to exhibit excessive knee flexion throughout stance. The knee control strategies selected by these subjects may be a result of the proprioceptive and/or strength deficits of the individuals.
Moment data revealed a delayed peak PF moment for all braces in S1, for the posterior shell only in S2. However, the period during which a PF moment occurs (initial contact through 14 percent GC in controls) is delayed most for the posterior shell in both subjects, slightly delayed for the anterior shell in S1 only. At the knee, however, peak knee moment during loading response is reduced from normal in all braces for both subjects, an indication that the strategy of both subjects at the knee is to reduce the quadriceps demand. S1 achieves this by extending the knee prior to loading, and S2 by contacting with the knee already flexed.
Energy cost data revealed that the rate of O2 use was similar for all braces for both subjects at 5 min of a 20-min walk. S1 showed an increase in the rate of O2 use after 10 min in all braces, which was not seen with S2. In fact, S1 was unable to walk more than 10 min, while S2 completed the 20-min collection period. For all six of the tested subjects, only S2 was able to walk the full duration.
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 ability to walk and to provide long-term foot protection.
[221] DEVELOPMENT OF LOWER EXTREMITY ORTHOTICS FOR CHILDREN WITH MYELOMENINGOCELE
Donald McNeal, PhD; Samuel Landsberger, ScD; Richard
Fite, CP; Vicente Vargas, BSME; Carin Caves, BA
Rehabilitation Engineering Program, Rancho Los Amigos
Medical Center, Downey, CA 90242
Sponsor: National Institute of Disability and Rehabilitation Research, U.S. Department of Education, Washington, DC 22202
PURPOSE--The aim of this project is to design improved bracing for the person with myelomeningocele. 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.
PROGRESS--A number of simple leaf-spring type AFOs have been fabricated, as proof of concept, from pre-impregnated carbon fiber (pre-preg) cloth. The use of composite pre-preg permits a strong and lightweight AFO to be custom-manufactured from a cast mold. The pre-preg cloth is applied over the cast and then heat cured, under vacuum, in a common fabrication oven.
A modification of the standard curing process of the composite has the potential to advance the overall fitting and fabrication process as well as the design of the brace itself. It was found that by partially curing the composite part while it is draped over the production mold, the material would, after removal and cooling, hold its laminated integrity while allowing the orthotist to hand-modify it to the patient. The part is then returned to the oven for final cure. This advance in process may allow the manufacture of modular shaped and sized AFOs to be distributed to orthotists in the partially cured state, with no need for cold storage or special handling. They can then be custom shaped by hand to the patient. This material is also heat post-formable with common orthotic tools. These advances eliminate some of the traditional problems of composite AFO manufacture, including the noxious (sometimes toxic) smell released during production, the difficulty in modification for patient fit at delivery, and adjustment for later changes as needed.
In the KAFO design project, successful fabrication of a prototype cantilever (single upright) KAFO has been accomplished. It is a single-upright design with smooth, flowing curves for enhanced strength and cosmesis. To complete the orthosis, an orthosis-to-patient interface of molded polypropylene was drape-vacuum molded, and Velcro straps were attached to the thermoplastic. A rugged Teflon-coated aluminum bearing appears suitable for the single-axis knee joint. This bearing was epoxied into place between the carbon fiber layers of the proximal part, and a clevis overlap was designed into the distal part.
FUTURE PLANS--The new pre-preg material will be used to laminate several AFOs for mechanical testing and, ultimately, evaluation with human subjects. Following an investigation of the failure modes of the material, with attention to the possibility of injury from sharp fracture edges, a safe design will be tested on team member controls prior to an in-clinic evaluation. A suitable interface between the carbon fiber and wearer, such as a liner material, will be developed as needed. Alternative composite AFO designs will be evaluated including anterior or posterior open-calf sections. The new partial cure process will be further investigated. The aim will be to explore design variations to best exploit the new material and fitting process. Comparison with conventional polypropylene AFOs will be made in terms of wearer comfort, gait performance, brace weight, bulk and cost.
[222] MOBILE ARM SUPPORTS FOR CHILDREN
Samuel Landsberger, ScD; Julie Shaperman, MSPH, OTR; Meg
Mitani, BS, OTR; Vicente Vargas, BSME; Kevin Caves, BSME;
Donald McNeal, PhD
Rehabilitation Engineering Program, Rancho Los Amigos
Medical Center, Downey, CA 90242
Sponsor: National Institute of Disability and Rehabilitation Research, U.S. Department of Education, Washington, DC 22202
PURPOSE--Mobile arm supports (MAS) are wheelchair-mounted mechanical linkages designed to support the weight of the arm and provide assistance to shoulder and arm motions. They have improved the function and independence of many individuals with flaccid paralysis or paresis of the shoulder and elbow flexor muscles. Problems with commercially available designs have limited their use in spite of their low cost and functional benefits. Drawbacks include complexity of the set-up and adjustment procedures, poor cosmesis, link interference, and doorway clearance. This project aims to improve MAS design to address these deficiencies.
PROGRESS--A survey of MAS users has been conducted to establish design goals. The results, combined with direct observations of users and input from experienced clinicians, provided valuable input to and stimulus for 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 multi-link articulated arm for the MAS has been developed and shows promise. It protrudes less and is more flexible in configuration, so it offers less interference to passage through door frames and around tables. Several prototype wheelchair mounts to facilitate arm balance adjustment have been designed and are under evaluation.
Clinical trials of the new mobile arm support began in early 1997. To date, 12 persons, mostly children, have tried the device. A User Group of 10-12 children is being formed to work with the project team throughout the developmental phase. This will enable prompt testing of various design features and quick feedback from a knowledgeable group of children and their parents.
RESULTS--The survey of MAS users documented that over half the respondents acknowledge a benefit from their MAS and continue to use it for a variety of activities, including eating, typing, playing games, and simple arm exercise. Seven users employ the device to help pilot their power wheelchairs. This result was a surprise since it was assumed that the mobility of the arm in the support might pose stability problems for joystick control. Complaints included difficulty in adjusting and maintaining the MAS balance alignment, device bulk (especially in clearing doorways), and poor appearance.
User trials of the new MAS and mounts are providing valuable insight into both benefits and drawbacks of the design. Link geometry and segment lengths are important factors in allowing both full range of motion and avoiding interference with the pivoting trough that supports the forearm. Appropriate bearing selection is crucial in providing low-friction motion while maintaining reasonable cost. The enhanced cosmesis is appreciated. Industry has expressed interest in producing an improved MAS, and therapists outside Rancho have indicated a desire to try it when it becomes available.
FUTURE PLANS--A new mounting system will be selected from among several candidates. The design must prove itself satisfactory for a number of clinicians and MAS setups, and provide easy attachment to the wheelchair and quick adjustment of the MAS. Expanded clinical trials of both the mount and the entire new MAS system will then be initiated. The ability to quickly relocate the MAS from the wheelchair to a pre-adjusted mount on a desk or table will be investigated as a useful option. Improved performance must not come at too high a price, so design for low-cost manufacture of all components will remain a priority.
[223] POWERED ARM ORTHOSIS
Allen H. Hoffman, PhD; Holly K. Ault, PhD
Mechanical Engineering Department, Worcester Polytechnic
Institute, Worcester, MA 01609; email:
ahoffman@wpi.edu
Sponsor: National Science Foundation, Arlington, VA 22230
PURPOSE--A powered arm orthosis was developed to aid those who suffer from muscular dystrophy. The purpose of the device was to provide the user with a powered, controlled arm movement that required minimum muscle exertion to counteract gravity. Specific goals were to enable the user to independently perform tasks such as grooming and feeding.
METHODOLOGY--The orthosis is designed to mount on an electric wheelchair and provides two powered degrees of freedom: shoulder rotation in the sagittal plane, and elbow flexion/extension. Passive shoulder rotation about the vertical axis is also provided. The powered movements are controlled by two toggle switches activated by the opposing hand. The orthosis uses chain drives and is powered by two 12 VDC motors mounted on the back of the wheelchair.
RESULTS--The device was tested by three nondisabled volunteers and was successfully operated to provide the desired grooming and feeding functions. Elbow flexion was independently controlled. However, shoulder rotation simultaneously caused a small amount of elbow flexion to occur.
FUTURE PLANS/IMPLICATIONS--The prototype powered arm orthosis successfully demonstrated the feasibility of a wheelchair-mounted design. A second generation prototype, powered by two hydraulic cylinders, is currently under construction. This new design will completely uncouple shoulder rotation from elbow flexion.
[224] LOGIC-CONTROLLED ELECTROMECHANICAL FREE-KNEE ORTHOSIS
Kenton R. Kaufman, PhD, PE; Steve Irby, MS; David
Sutherland, MD
Mayo Clinic/Mayo Foundation, Orthopedic Biomechanics
Laboratory, Guggenheim 128, Rochester, MN 55905; Motion
Analysis Laboratory, Children's Hospital, San Diego, CA
92123-4282; email: kaufman.kenton@mayo.edu
Sponsor: National Center for Medical Rehabilitation Research, National Institute of Child Health and Human Development, Rockville, MD 20852
PURPOSE--This project addresses the problem of restoring lower limb function to persons who require the use of a knee-ankle-foot orthosis (KAFO) for ambulation and must have the knee locked for stability during gait. Currently, these persons are usually fitted with either a conventional KAFO that has a knee joint equipped with a manual mechanical lock, or with a free-knee orthosis equipped with an eccentric knee joint. These orthotic schemes result in a lack of knee movement during the swing phase of gait, producing inefficient gait. The goal of this project is to design, develop, and test a small, lightweight, electronically controlled knee joint that can be installed on a conventional KAFO. The knee joint will unlock during the swing phase of gait and lock during the stance phase of gait.
METHODOLOGY--This new orthotic system is composed of two major parts: mechanical hardware and an electronic control system. The mechanical hardware consists of a standard polypropylene orthosis, a mechanical clutch, and a solenoid to release the clutch when required. The electronic control system consists of sensors which go in the shoe of the subject to sense the position of the foot. When the foot is on the ground, a logic circuit keeps the clutch locked. When the foot is in the air, the same logic circuit unlocks the clutch and lets the knee swing freely.
PROGRESS--This research project has developed a new design which can be adapted to an existing KAFO. This system has been successfully tested on four subjects with paralysis of the lower limb. Dynamic gait analysis has shown improvements in the knee motion pattern while using the new KAFO. The knee swing-phase motion pattern approaches the motion of a nonimpaired individual. The improvement in knee motion during swing was effective in lowering the energy required for walking. Energy consumption measurements were obtained on level ground and on a slope with a 5 percent incline. The oxygen consumption rate and energy costs were significantly lower when the swing phase knee motion was unrestricted during gait.
FUTURE PLANS--This research will be continued in the future. Plans are to miniaturize the electronics and integrate all elements into the orthosis.
IMPLICATIONS--Surveys show that rejection rates for KAFOs range from 60 to nearly 100 percent. This high rejection rate is due to the increased energy requirements for locomotion when using conventional KAFOs. The newly proposed orthosis design which allows free knee motion during the swing phase of gait requires less energy to walk. It is anticipated that this improvement in walking efficiency will lead to an increased acceptance rate by those who require a KAFO for morbidity.
[225] DETERMINATION OF THE EFFECT OF RANGE OF MOTION CHANGES IN AN ARTICULATED ANKLE FOOT ORTHOSIS ON LOWER LIMB MUSCLE DEMANDS
Mukul Talaty, MS, BME; Rahamim Seliktar, PhD; Alberto
Esquenazi, MD; Barbara Hirai
Gait and Motion Analysis Laboratory, MossRehab Hospital,
Philadelphia, PA 19141; Biomedical Engineering and Science
Institute, Drexel University, Philadelphia, PA 19104; email:
mctalaty@aehn2.einstein.edu
Sponsor: Post Polio Clinic of the Albert Einstein Healthcare Network; the Calhoun Fellowship Endowment of Drexel University, Philadelphia, PA
PURPOSE--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 (ROM) in an articulated ankle foot orthosis have been measured in a Post Polio Syndrome (PPS) 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 ROM 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 ROM 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 PPS subjects have been evaluated to assess whether neuromuscular deficiencies affect the trends found in controls. 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 PPS 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 ROM constraints on muscle demands are pending.
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Last revised Fri 04/30/1999