[174] 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;
Hans R. Lehneis, PhD, CPO
New York University Medical Center, New York, NY; VA
Medical Center, New York, NY 10010; email:
vlh3@is2.nyu.edu
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, effectively and efficiently to design and manufacture well-fitting, comfortable, and functional orthopedic footwear for US veteran pedorthic patients.
METHODOLOGY--To achieve this objective, the following research protocol has been established: [nl]1. Compile a database of medical/podiatric/pedorthic conditions, and the corresponding footwear prescriptions and designs issued in treatment thereof, for a representative sample of VA pedorthic patients, including digitizing the custom orthopedic lasts and associated footwear upper patterns conventionally designed and produced for these patients;
PROGRESS--Medical/podiatric/pedorthic data on 289 VA pedorthic patients was compiled, and their custom orthopedic lasts and associated footwear upper patterns, together with the stock lasts from which their orthopedic lasts were constructed, were optically digitized and entered in the project database. The compiled data were analyzed to establish minima, maxima, averages, and standard deviations on the types and range of VA pedorthic patient conditions, footwear prescriptions, and corresponding orthopedic footwear last and pattern designs and modifications used in treatment thereof. From these results, specifications for a VA pedorthic CAD/CAM system were derived, and a system developed.
The pedorthic CAD/CAM system runs on a PC workstation with the Microsoft WindowsNTTM operating system. It supports dual monitor, multiple window display of 3-D shaded solid and 2-D cross-sectional views of digitized models of patient feet and selected orthopedic lasts and footwear patterns, for enhanced visualization and increased ease of design and modification. Either optically digitized scans of patient feet or prescribed sets of pedal measurements can be input into the system and used for custom orthopedic footwear design. If the feet are severely deformed, digitized models of them are required; these can be directly modified to create custom orthopedic lasts. If severe pedal deformity is not present, then either measurements or digitized scans of the feet can be used to input, manually (or automatically) select, and automatically grade optimally matching models from the system's pre-digitized orthopedic library of (currently) 112 pre-digitized lasts.
In addition to the usual CAD system design tools, such as model rotation, cross-sectional display, and global and localized radial magnitude modification, the VA Pedorthic CAD System has modification region and design template multiple landmark linking, with automatic regional scaling. It also has feature and regional boundary identification and registration; menu and hot key selection of common modifications (toe box expansion, bunion relief, metatarsal pad, scaphoid pad, medial and/or lateral wedges, and the like); variable reference center selection and realignment ability, including forefoot abduction and adduction; advanced spline surface smoothing; input of Tekscan FScan (or similar system) pedal plantar stress measurements for last plantar surface-insole design; variable plantar sole thickness specification for elevation control and leg length discrepancy compensation; etc. Automated 3-D last to 2-D shell-flattening capabilities have also been developed and incorporated into the system, together with footwear upper pattern selection from the predigitized system pattern library, with automatic grading, piece definition, and design modification and styling capabilities.
CAM toolpath correction, clearance, and surface-smoothing software for last manufacture has been written and tested, and the VA Prosthetic CAM milling machine upgraded to enable carving of rigid polyurethane foam and high density polyethylene lasts. Clinical trials by several certified pedorthists at the VA Medical Center, New York with 7 control subjects and 39 VA pedorthic patients have been successfully conducted to date with the system.
[175] CLINICAL TRIAL OF FOOTWEAR IN PATIENTS WITH DIABETES
Gayle E. Reiber, MPH, PhD; Doug Smith, MD
Health Services and Epidemiology, and the Department of
Orthopaedics, University of Washington, Seattle, WA 98185;
VA Puget Sound Health Care System (152), 1660 S. Columbian
Way, Seattle, WA 98108; 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)
PURPOSE--Lower limb ulcers and amputations are a common and costly problem; such ulcers precede about 85 percent of diabetic amputations. Nearly half of the events that begin the causal pathway leading to ulcers and amputations are footwear-related. Yet the efficiency of footwear in preventing ulcers and amputations in high-risk diabetic populations has received limited experimental investigation. Randomized trials have not assessed the combined contribution on ulcer prevention of therapeutic shoes and different types of inserts, nor have they addressed patient footwear adherence.
METHODOLOGY--This study is a 3-year randomized clinical trial designed to determine the extent to which study shoes and insoles would reduce the incidence of reulceration in diabetic individuals with a prior history of foot ulcers and the estimated costs of ulcer prevention using footwear strategies.
PROGRESS--In mid-1997 the study staff was recruited and trained, and the study protocol, procedures manual, and study forms were finalized. A computerized data entry and management system was designed and implemented. Over 3,300 letters to potentially eligible patients and subsequent phone calls has yielded a study-eligible population of ;sl12 percent who are eligible and willing to participate in the study. The major reasons for persons not participating were that they were not diabetic, had no prior foot ulcer, or were currently wearing custom orthopaedic footwear. We have enrolled or scheduled for enrollment 366/400 of our clinical trial participants and anticipate completing enrollment during October 1998. Enrollment took 6 mo longer than projected. Adherence with the assigned footwear is high. The study staff is photographing and documenting all patient foot lesions.
FUTURE PLANS --We shall complete patient enrollment and conduct the follow-up of study participants for 2 years, as outlined in the study protocol.
[176] ANALYSIS AND OPTIMIZATION OF HYBRID SYSTEMS FOR WALKING RESTORATION OF PARAPLEGIC PATIENTS
Maurizio Ferrarin, DrEng, PhD; Marco Rabuffetti, DrEng;
Raffaella Spadone, DiplEng; Antonio Pedotti, PhD
Centro di Bioingegneria, Fondazione Pro Juventute Don
Gnocchi IRCCS, Politecnico di Milano, I-20148 Milano, Italy;
email: ferramau@mail.cbi.polimi.it
Sponsor: Italian Ministry for Health Care
PURPOSE--This project seeks to develop and apply an evaluation protocol to analyze the locomotor pattern of persons with paraplegia, walking with both pure mechanical orthoses and hybrid systems (orthoses combined with FES). The aim is to obtain a set of tools for comparing external walking devices and for adapting them to each patient, taking into consideration both the mechanical adjustment and the electrical stimulation pattern optimization.
METHODOLOGY--A group of subjects with complete thoracic spinal cord lesion have been selected and trained, following a specific rehabilitation program. It comprehends a muscle conditioning phase with muscle electrical stimulation and a walking training with orthoses (LSU-RGO and ARGO) and FES system (Parastep). Different evaluations (clinical, biomechanical, energy consumption, and so forth) during the training period and after some months of functional use of the adopted walking system have been programmed. In particular, concerning the biomechanical protocol, a multifactorial gait analysis system has been adopted to collect simultaneously all significant data about assisted walking. It consists of an ELITE system for kinematic analysis, a force platform for ground reaction force detection, an 8-channel electromyograph to record myoelectric activity of supralesional muscles, and a personal computer with suitable software to store, process, and graphically represent all collected data. Energy consumption evaluation is performed through the collection of heart rate and expired air during walking.
PROGRESS--The acquisition protocol developments and validation have been performed successfully. Concerning biomechanical protocol, we have positioned particular markers over technical reference points to calibrate and reconstruct anatomical landmarks covered during movement. A set of interesting variables has been individuated (spatio-temporal parameters, time course of upper and lower limb joint angles, center of gravity displacements, joint torque and power, GRF impulses). An instrumented chair has been developed for isometric measurement of knee torque induced by muscle stimulation. It is used to monitor changes in muscle strength and endurance during the muscle conditioning program.
RESULTS--Muscle conditioning procedure and the specific training was performed on a first group of subjects. Assessments made during the training showed the improvement on muscle strength and endurance, and first biomechanical acquisitions performed during walking with LSU-RGO and ARGO (with and without FES) showed interesting differences in locomotor strategy correlated with the different mechanisms involved in the orthoses and the influence provided by the electrical stimulation on walking pattern. In particular, the analysis of modifications provided to the LSU-RGO orthosis by adding horizontal rotation to the hip joint showed an improvement on pelvis rotation. Energy consumption evaluations showed that the addition of FES to a pure mechanical orthosis reduces the overall cost of locomotion only for high gait speed, and seems to improve the hemodinamic adaptation to exercise.
FUTURE PLANS--Acquisitions on subjects using LSU-RGO and ARGO with and without FES will be repeated on others, also after some months of functional use of the orthoses. A set of trials with modified stimulation patterns are planned, in order to find criteria for single subject pattern optimization. When walking training is completed, we shall conduct biomechanical analysis using the Parastep system and compared the results with those of the previous subjects, mainly from the point of view of energy consumption.
[177] 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. D'Ambrosia,
MD
Department of Orthopaedics, School of Medicine in New
Orleans, Louisiana State University Medical Center, New
Orleans, LA 70112; email: rbarat@lsumc.edu
Sponsor: Louisiana Board of Regents, Baton Rouge, LA 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--We recruited 70 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, into the program and fitted them 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.
[178] DETERMINATION OF THE EFFECT OF RANGE OF MOTION CHANGES IN AN ARTICULATED ANKLE FOOT ORTHOSIS ON LOWER EXTREMITY MUSCLE DEMANDS
Mukul Talaty, MS, BME; Rahamim Seliktar, PhD; Alberto
Esquenazi, MD; Barbara Hirai
Gait & Motion Analysis Laboratory, MossRehab Hospital,
Philadelphia, PA 19141; School of Biomedical Engineering,
Science, and Health Systems, Drexel University,
Philadelphia, PA 19104; email:
mtalaty@aehn2.einstein.edu
Sponsor: Post Polio Clinic of the Albert Einstein Healthcare Network
PURPOSE--This is a continuing project to utilize EMG signals to assist in the orthotic alignment procedure. 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 (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.
METHODOLOGY--Four subjects with no neurological or orthopaedic conditions that may influence gait and four subjects with PPS have been evaluated to date. The unaffected subjects used off-the-shelf orthoses, and the PPS 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--Alternative computations (peak force and moment arm contributions to joint moments, force impulses) are being done to try to further understand the mechanism behind the changes in EMG noted. PPS subjects were evaluated to assess if 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 data were 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 suggest that the initial response to any new condition may be an extreme one, in which there was either maximal or minimal muscle activity.
FUTURE PLANS--Correlation of kinetic effort measures and EMG patterns is planned in an effort to further understand the factors which give rise to the compensations observed. Testing of additional subjects and developing a musculoskeletal model to predict the effect of orthotic range of motion constraints on muscle demands are pending. In general, trends in compensation to the orthosis will be monitored as part of an ongoing effort to document and model compensation mechanisms.
[179] THE ROLE OF ORTHOTIC INTERVENTION IN RESOLUTION OF PLANTAR FASCIITIS
Mukul Talaty, MS, BME; Alberto Esquenazi, MD; Barbara
Hirai; John Whyte, MD, PhD; Mary Ann Keenan, MD
Gait & Motion Analysis Laboratory, MossRehab Hospital,
Philadelphia, PA 19141; Neuro-Orthopaedic Program, Albert
Einstein Medical Center, Philadelphia, PA 19141; email:
aesquena@aehn2.einstein.edu;
mtalaty@aehn2.einstein.edu
Sponsor: Department of the Army; Post Polio Clinic of the Albert Einstein Healthcare Network
PURPOSE--Our 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--Twenty-seven total subjects from two groups, Post Polio Syndrome (PPS) and control, with clinically documented plantar fasciitis, have completed the protocol. Subjects are fitted with custom orthoses (MAFOs for PPS, in-shoe for 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 of the lower limbs, and walking speed. The above data are recorded both with and without the orthosis; order of testing is randomized. Approximately 1 mo later, severity of plantar fasciitis symptoms is reassessed.
PROGRESS--EMG analyses has shown differences from walking with and without brace, particularly in the soleus muscle.
PRELIMINARY RESULTS--Data from the visual analog scale ratings showed significant reduction of pain after one month of orthosis use in both groups. Ipsilateral soleus integrated EMG indicated a significant reduction in activity in subjects using the insert during 10-45 percent of the gait cycle. Subjects using MAFOs showed a modest reduction. During the concentric contraction phase of the gait cycle (45-60 percent), there was reduction in integrated soleus EMG of MAFO subjects but an increase in the activity of the subjects using the insert.
Integrated EMG data were normalized to the total activity in the stride for each condition to allow determination of how activity was allocated or shifted in reference to the gait cycle for each condition. The MAFO group showed a decrease for both the eccentric as well as the concentric phase of soleus activity. The insert group showed a decrease in the eccentric phase, and a nearly commensurate increase in the eccentric phase, indicating that the soleus generated less activity during the midstance phase, but made up for this by generating more activity during the push-off period. Reduction and reallocation of activity and perhaps pulling force generated by soleus during walking in a MAFO or custom insert may be responsible for reduction of strain on the plantarfascia and an amelioration of symptoms.
Variability of integrated EMG data was observed to be consistently higher in the condition without the orthosis for both the insert and the MAFO group, and this may be indicative of level of comfort or familiarity with the orthosis. This is despite the fact that the means of the integrated EMG data were generally the same or lower. So, subjects display a higher coefficient of variability for EMG data when not using their orthosis.
FUTURE PLANS--Kinetic parameters will be analyzed to corroborate hypotheses about shifting of muscle demands due to biomechanical changes produced by the orthoses. Trends in how gait parameters are affected in the Post Polio Syndrome population as compared to the non-Polio population will also be analyzed. In general, trends in compensation to the orthosis will be monitored as part of an ongoing effort to document and model compensation mechanisms.
[180] ORTHOTICS FOR MYELOMENINGOCELE PATIENTS, TEENAGE VERSUS CHILDHOOD
Jacquelin Perry, MD; Jacklyn G. Heino, PT; Sara J.
Mulroy, PhD, PT; Sreesha Rao, MS; JoAnne Gronley, DPT
Pathokinesiology Laboratory, Rancho Los Amigos Medical
Center, Downey, CA 90242; web: http://www.ranchorep.org
Sponsor: National Institute of Disability and Rehabilitation Research (NIDRR), 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 teen. The specific goals are to delineate the differences in gait of pediatric versus teenage patients; to compare the strengths and range of motion of the two subject groups; and to differentiate orthotic forces, foot stability, and biomechanics of three ankle-foot orthoses (AFOs) and standard knee-ankle-foot orthoses (KAFOs).
METHODOLOGY--Children (4-7 years) and teenagers (12-17 years) with MMC lesions (lumbar or sacral functional levels) who rely on orthoses to walk are being recruited. Individuals using KAFOs will be tested with their normal orthoses; those using AFOs 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).
PROGRESS--Currently, 14 subjects (4 children, 10 teens) have been admitted into the study and 9 have completed testing.
RESULTS--Stride characteristics, kinematics, foot pressures, and energy cost have been analyzed in six subjects. No significant differences for velocity, cadence, or stride length were found among the three AFO designs. On all three parameters, however, the anterior shell orthosis is consistently closer to normal than the other two designs.
All three orthoses have prolonged heel-only contact. In mid stance, first metatarsal contact preceded the fifth metatarsal. Heel off is delayed in all three designs compared to normal, with greatest delay in the articulating and least delay in the anterior shell orthosis. In terminal stance, only the toes made floor contact. This foot contact pattern is generally unstable, a fact supported by increased loading response duration in comparison to normal.
During terminal stance and preswing, all three orthoses allowed excessive dorsiflexion. The anterior shell orthosis provided the best control, preventing further increase in dorsiflexion in preswing, while dorsiflexion continued to increase in the other two designs. Although the articulating orthosis is designed with free plantar flexion (dorsiflexion stop at zero), there was no significant difference in ankle plantar flexion in loading between designs. Knee angle at initial contact also was significantly different between braces with the anterior shell closely approximating normal, posterior shell in hyperextension, and articulating brace causing knee flexion. Flexed knee at initial contact (articulating brace) reduced the heel rocker. Although not significant different, the anterior shell brace tends to control the knee best during mid stance as well.
Foot pressure inside the orthoses was consistent among designs with less pressure when compared to nonimpaired children. The lower pressures may be partially explained by a reduced gait velocity in the MMC subjects.
Energy cost and rate were similar across all designs, yet higher for subjects with MMC than in control subjects. The self-selected velocity of MMC subjects in this study required 67 percent of VO2 maximum in comparison with that of controls, who required 28 percent VO2 maximum. Only one subject tolerated walking for the 20-min test period. Walking duration was correlated with level of lesion (p<0.01). Neither O2 rate nor cost increased with sustained walking; therefore, local muscle fatigue from severe exercise intensity levels was the probable reason for the short walking duration.
FUTURE PLANS--Recruitment and testing of subjects will continue. Data analysis of foot pressure, kinematics, and stride characteristics 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 selection to facilitate the patients' ability to walk and to provide long-term foot protection.
[181] MOBILE ARM SUPPORTS FOR CHILDREN
Samuel Landsberger, ScD; Julie Shaperman, MSPH, OTR;
Margaret Mitani, BS, OTR; Vicente Vargas, BSME; Kevin Caves,
BSME; Jack Greenfield, CO, Donald McNeal, PhD
Rehabilitation Engineering Program, Rancho Los Amigos
Medical Center, Downey, CA 90242; email:
alin@ranchorep.org
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 elbow and shoulder motions. Problems with existing designs have limited their use despite their low cost and functional benefits. A survey of users and experienced clinicians identified the drawbacks: complexity of set-up and adjustment procedures, poor cosmesis, link interference, and doorway clearance. The design goals for the new MAS address these deficiencies to provide ease of adjustment, low profile, and attractive cosmesis along with the requisite ease of motion.
PROGRESS--A multilink segmented arm has been designed and tested by members of a user group of patients. In order to ease set-up and adjustment, several new types of wheelchair mounts have been designed, evaluated, and tested. The current model adjusts by turning a wheel in the direction that will offer the patient more gravity assistance. No tools are needed to make adjustments. Another innovation is a "bubble" on the mount that allows the clinician to set the arm to a zero position easily before fine-tuning the adjustment. In conjunction with the bubble, the design will include a marker system to identify the optimum position found for each arm, so the system can readily be returned to this position by parents or caregivers if it is pushed out of alignment during transport or from bumping furniture.
Trials to date indicate high user acceptance. Almost all of the children prefer its appearance, and they find the low profile especially desirable when driving the wheelchair through a doorway or in a crowded area. We have progressed from single-session clinical trials to extended one with three patients. The extended trials will determine initial durability and point out any functional problems prior to sending the MAS to patients in clinics outside the local area. At least 12 therapists and patients are currently awaiting receipt of the MAS for extended testing in their clinics. Doctors at the Los Angeles Unit of Shriners Hospital for Children have invited the staff of the Rehabilitation Engineering Program to consult with them on use of MAS for children in their arthrogryposis clinic. Experience has shown that there is considerable potential for functional improvement with ambulatory children who use the MAS with table mounts.
FUTURE PLANS--We are making final adjustments to the MAS multilink arm and mount in preparation for a larger-scale production run for clinical testing. The marker system to allow easy return to selected adjustment will be included in this design. Therapists are preparing patient selection forms and installation instructions for the MAS so it can be made available for extended testing soon. Following testing, we will resume contacts with industry. Several manufacturers have expressed interest in producing an improved MAS.
[182] DEVELOPMENT OF LOWER EXTREMITY ORTHOTICS FOR CHILDREN WITH MYELOMENINGOCELE
Adrian A. Polliack, PhD; Richard Fite, CP; Samuel
Landsberger, ScD; Donald R. McNeal, PhD; Vicente Vargas,
BSME
Rancho Rehabilitation Engineering Program, Rancho Los
Amigos Medical Center, Downey, CA 90242; email:
polliack@ranchorep.org
Sponsor: National Institute of Disability and Rehabilitation Research (NIDRR), U.S. Department of Education, Washington, DC 22202
PURPOSE--Myelomeningocele is a congenital disorder that is the most severe form of spina bifida resulting in lower limb paralysis and paresis. Orthotic support for this population has always been difficult but important for the physiological and social development of the child. The purpose of this project is to design improved bracing for this population, continuing with the development of pre-impregnated (pre-preg) composite materials and the investigation of next generation fabrication techniques with the potential to overcome several current problems of ankle-foot (AFO) bracing. The results of this work may lead to stronger, stiffer, and lighter braces for the wearer, and improved methods of brace fitting, fabrication, and delivery.
PROGRESS--A unique group of epoxy pre-preg fiber cloths of carbon, aramid, and glass fibers in an array of weave designs, storable at room temperature, has been used to produce a number of posterior shell AFO designs that can be custom-manufactured over a positive cast mold by cutting and placing the cloth over the cast in accordance with the desired shape. Section thickness is achieved by layering. The tackiness of the pre-preg makes self-adhesion possible and there is no noticeable odor during lay-up. The layered mold is encased in a high-temperature nylon vacuum bag and placed in a standard convection oven to be cured at 154.4 °C for one hour under a vacuum of 736.6 mmHg.
Research is underway to determine the ability to fabricate partially cured AFOs, but allow for enough cross-linking for the AFOs to be structurally adequate. The intent is to allow the orthotist to hand and/or heat modify the AFO to the patient or patient model, before curing it to completion. The advance in this process may allow for 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, and then fitted according to patient size and condition before curing in a standard oven. A study will also begin to investigate the ability to post-form the AFO, once cured, and to assess delamination or structural damage.
Other tests have included extensive mechanical characterization of carbon and Kevlar® cured pre-preg by way of test coupons prepared for tensile, bending, and compression analysis. These results are compared with 4.76 mm standard polypropylene test coupons.
Six AFOs have been custom-made to four subjects, and these have been tested to assess a multitude of design factors, including choice of material(s), AFO geometry, and durability. The subjects performed their typical work-related activities. This part of the project is on-going. Safety concerns are being investigated with respect to handling and fabrication, human use of the finished AFO, and dermatological effects.
FUTURE PLANS--A number of parallel investigations will occur over the next year, starting with additional investigations of safety in both handling and AFO use. Fatigue and stiffness testing will be conducted to assess durability and optimization of AFO geometry and material selection. Control subjects will continue to test-wear AFOs and provide feedback about comfort, design, and other related observational experiences. Clinical AFO testing of myelomeningocele children will begin soon. Here, the study will include subjective feedback about the AFO design, comfort, and cosmesis. Extensive gait analysis will be performed and objective comparisons made with the subject's existing polypropylene AFO designs. Additionally, the proposed novel fabrication process will be explored further.
[183] LOGIC-CONTROLLED ELECTROMECHANICAL FREE-KNEE ORTHOSIS
Kenton R. Kaufman, PhD, PE; Steve Irby, MS; Jeffrey
Basford, MD, PhD; 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 the gait and lock during the stance phase.
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 in the shoe of the subject to sense the position of the foot and an electronic control system composed of digital logic integrated circuits. When the foot is on the ground, the logic circuit keeps the clutch locked. When the foot is in the air, the same circuit unlocks the clutch and lets the knee swing freely.
PROGRESS--An optimized wrap spring clutch with a torque capacity of 113 N·m has been produced. Extension stops have been added to the design in order to limit recurvatum, a common complaint of ambulatory patients with quadriceps insufficiency. The clutch and electronic control package has been designed to interface with a commercially available modular KAFO system. The modular KAFO provides immediate accommodation to a wide patient population. This will make the brace system amenable to use in a rehabilitation setting as well as providing a means to test the brace on potential users before undertaking the effort and expense of fabricating custom orthoses. New electronic circuitry has been designed that results in significant size and weight reductions. Control circuitry and battery power are now held in a single enclosure measuring 4×8×14 cm and weighing 0.462 kg. This represents a reduction of 45 percent in volume and 19 percent in weight over previous designs.
FUTURE PLANS--This research project will be continued in the future. Brace system durability will be tested by fatigue testing of the knee joint control mechanism and the footswitch sensors to 1 million cycles. Electronic control circuitry will be refined further to minimize power requirements, and hence reduce battery size and weight. Plans include further testing to validate efficiency on patients with neurological and musculoskeletal deficits.
IMPLICATIONS--Surveys show that rejection rates for conventional KAFOs range from 60 to nearly 100 percent. This high rejection rate is due primarily to the increased energy requirements for locomotion when using them. 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 mobility.
[184] DEVELOPMENT OF A FULLY ADJUSTABLE POST OPERATIVE HIP ABDUCTION ORTHOSIS
Devon Ostrom, MASc; Ivan Samilla, CO(c); Kimberley
Parker, MASc, PEng; Stephen Naumann, PhD, PEng; John H.
Wedge, MD, FRCSC; Jane Cribbs, RTO(c); Tony Panfili
Bloorview MacMillan Centre, 350 Rumsey Road, Toronto, ON
M4G 1R8, Canada; The Hospital for Sick Children, 555
University Ave., Toronto, ON M5G 1X8; email:
naumann@utcc.utoronto.ca
Sponsor: Ontario Rehabilitation Technology Consortium funded by the Ontario Ministry of Health
PURPOSE--Children with cerebral palsy who undergo surgical procedures about the hip are required to wear a cast or hip abduction orthosis for at least 6 to 12 mo following surgery. This device is prescribed to maintain hip adductor and flexor lengths, and prevent or control the recurrence of the deformity. The usual hip abduction orthoses are custom made and not covered by the Assistive Devices Program of the Ministry of Health. As these devices do not grow with the child, they subsequently may increase the costs to the family. A less expensive option is to use plaster casts, but they require refurbishing prior to long-term use and have disadvantages relating to hygiene, comfort, and appearance. There is a need for a hip abduction orthosis that is adjustable and will grow with the child. This device should be easy to fit and to clean as well as being reasonably priced.
PROGRESS--The Computer Aided Design (CAD) drawings of the hip abduction orthosis have been finalized and the first prototype is currently being manufactured. The orthosis hinge design is based on the use of angular cams that offer adjustability in both flexion and abduction. The remainder consists of molded pelvic and hip sections and linking braces with predrilled and threaded inserts for ease of assembly and adjustment.
Currently two sizes of the orthosis have been developed to fit children aged 3 to 11. Ethics approval has been obtained to test the prototypes on children scheduled for hip-related surgeries at The Hospital for Sick Children. Questionnaires have been developed for the staff members involved with postoperative fitting to determine the effectiveness and fit of the prototype orthosis. We have also developed questionnaires for the caregivers to obtain feedback on how easy the device is to clean, fit, and remove.
FUTURE PLANS--Plans have been made to test one small and one medium-sized prototype. After reviewing feedback from the participants, the design will be finalized. This will allow final evaluation and technology transfer of the orthosis to proceed.
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