iotics

The Role of Pressure Distribution Measurementin Diabetic Foot Care tn.

Peter R . Cavanagh, Ph.D. ; Lee J . Sanders, D .P.M.; David S. Sims, Jr ., P.T. M.S.Pennsylvania State University, University Park, PA 16802 and Veterans Administration Medical Center,Lebanon, PA 17042

Sponsor : VA Rehabilitation Research and Development Service

Purpose—The purpose of this study was to deter-mine the value of pressure distribution measurementin the prevention of neuropathic plantar ulcerationsin the diabetic individual . Based upon a review ofthe literature and on our own previous work in thisarea, specific hypotheses tested were as follows : 1)There will be significantly higher pressures underthe forefoot and significantly lower pressures underthe toes in the diabetic patients, as compared to thecontrol group . 2) The above trends will becomemore marked over a two-year period . 3) Quantitativeassessment of the plantar pressure distribution willbe effective in identifying patients who are "at risk"for the development of lesions . 4) The group ofpatients receiving a program of enhanced foot carewill develop significantly fewer non-traumatic plan-tar lesions than the group receiving normal footcare.

Progress Phase 1 of the research program wascompleted . Activities at Penn State University in-cluded the completion of a calibration device forthe pressure platform, configuration of new com-puter hardware and development of software fordata collection, display and processing . A pool of100 possible diabetic subjects was identified at theLebanon VAMC.

Phase 2 was begun with a comprehensive medicalscreening of 87 diabetic patients and 41 non-diabeticindividuals . The examination included detailedmeasurements of sensation, foot structure and non-invasive vascular tests . Upon completion of thescreening process, 60 diabetics were selected forinclusion in the study . The criteria for inclusionwere vibratory perception thresholds > 20 units,loss of protective sensation by monofilament testing,history of previous plantar ulceration and structuralfoot deformities which would predispose the patient

53

to plantar ulceration . Patients selected were thenrandomly assigned to two groups—enhanced careand normal care . A third group of 30 subjects wasselected from the pool of non-diabetic subjects toserve as age- and weight-matched controls.

Initial pressure data was collected for the controlgroup subjects . Pressure distribution has been meas-ured every 4 months for the normal and enhancedcare groups . Three data collection sessions havebeen completed for each diabetic group with over2200 trials recorded . The enhanced care group re-ceived two pairs of special footwear consisting ofextra-depth shoes with soft molded insoles . Patientshave attended outpatient clinic visits every 4 to 8weeks to monitor their progress . An annual patienteducation conference has been provided to thenormal and enhanced care groups . Two of ourpatients have died, two have had cerebrovascularaccidents and two have dropped out of the studyfor non-medical reasons.

Preliminary Results—A subset of data consisting of12 subjects from each group (N 36) were selectedfor the purpose of performing a preliminary analysis.Comparison of peak plantar pressure means betweengroups showed a significant difference (p < 0 .03)for non-diabetic controls versus diabetics with ahistory of ulceration . No significant difference wasfound between non-ulcer diabetics and diabeticswith ulcers, but a clear trend was present, suggestinghigher pressures in the ulcer group.

Peak pressure at ulcer locations varied from 312to 1895 kPa. The highest pressures were noted underthe second metatarsal head . In general, the peakplantar pressure corresponded with the site of ul-ceration but exceptions were noted at the toes andheel.

The incidence of plantar lesions at the beginning

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Rehabilitation R&D Progress Reports 1957

of the study was 8 and 13 for the normal andenhanced care group, respectively . Since the deliv-ery of the special footwear to the enhanced caregroup there have been only 4 lesions . This representsa 69 percent reduction in the incidence of plantarinjuries in this group.

Diabetics with a history of ulceration had signif-icantly greater (p < 0 .005) deformity as comparedto the non-ulcer diabetic group . The most commondeformity was found to be clawtoes . Monofilamentthresholds were significantly greater in the diabeticswith ulceration as compared to non-diabetic con-

trols . No significant difference was found betweenthe two diabetic groups . Mean vibratory thresholdswere significantly different (p < 0 .001) between allthree groups . The minimum threshold at the site ofulceration was 13 .2 micrometers of displacement.

The vascular index did not vary significantlybetween groups but some trends were noted . Theindex tended to decrease in the non-ulcer diabeticgroup suggesting a mild decrement in blood perfu-sion . In contrast, the index in the diabetic ulcergroup was similar to the non-diabetic controls whichmay indicate decreased arterial compliance.

Effectiveness of Shock Absorbing Materials inReducing Heelstrike Forces in Walking

D.D. Moyle, Ph .D. ; M . Russo, M.S . ; E.W. Berg, M.D.; F . Piehl, M.D.Bioengineering Alliance of South Carolina, Clemson University, Clemson, SC 29634 ; William Jennings Bryan DornVeterans Administration, Columbia, SC 29203 ; and University of South Carolina School of Medicine, Columbia,SC 29208

Sponsor : VA Rehabilitation Research and Development Service ; Bioengineering Alliance of South Carolina

Purpose-Degenerative changes have been shownto be caused or worsened by mechanical factors, inparticular, repetitive loading . Mthough forces whicharise normally in walking are usually absorbed easilyby the musculo-skeletal system, this is not neces-sarily the case in subjects with joint pathology.Forces may cause damage to joints in people whoseshock-absorbing capabilities have diminished dueto age, trauma, or deformity . It may be possible toreplace some of this shock absorbency by usinginsole materials inserted into the shoes . The effec-tiveness of several of these materials was the subjectof this investigation.

Progress—A heel pad instrumented with eight pie-zoelectric ceramic discs served as the transducer tomeasure forces under the feet as subjects walkedon a treadmill . The heel pad was placed inside apair of specially-designed test shoes which all sub-

jects were asked to wear . Subjects walked at aconstant, comfortable speed throughout the test.Data was collected, stored and statistically analyzedon a desktop personal computer.

Preliminary Results.---Preliminary studies on normalindividuals showed that 10 materials out of 23 testedwere effective in reducing heel strike forces . Fourof these were used in a test on 10 subjects whoeither had to moderate osteoarthritis or had under-gone total joint replacement in the hips or knees.All subjects tested each of the materials and thesetests were compared to one with no insole in theshoe. Results showed that all four materials signif-icantly reduced both force and impulse (area underthe force-time curve) in all subjects . None of thematerials was found to be significantly better thanthe others in this capacity .

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Orthotics

Functional Kinesiology of Knee Bracing

Richard Shiavi, Ph .D. ; Thomas Limbird, M .D. ; Alvin Strauss, Ph .D.Veterans Administration Medical Center, Nashville, TN 37203 and Vanderbilt University School of Engineering,Nashville, TN 37235Sponsor : VA Rehabilitation Research and Development Service

Purpose—The objective of this project is to inves- Progress—The first major challenge is to measuretigate the effects of five functional braces on the the kinematics of the braced knee . A six-degree-of-kinesiology of the injured knee . Measurements will freedom goniometer has been designed and is beingbe made using a six-degree-of-freedom goniometry fabricated presently for this purpose . Testing of theand electromyography during walking and pivoting . goniometer and implementing necessary design

changes will be accomplished this year.

Therapeutic Evaluation of the VA San FranciscoTherapeutic Molded Shoe and Diabetic Risk Stratification

Richard M . Stess, D.P.M., and Peter M. Graf, D .P.M.Veterans Administration Medical Center, San Francisco, CA 94121

Sponsor : VA Rehabilitation Research and Development Service

Purpose—According to Levin, lesions of the footare responsible for more than one-fifth of the op-erations performed on diabetic patients . It wouldtherefore be prudent both financially and medicallyto define the diabetic population at risk and todevelop effective methods of intervention such thatpedal ulcerations and amputations can be preventedor minimized . The purpose of this project is to : 1)develop and conduct a series of non-invasive ex-aminations which will be used in assessing thepredisposition toward foot ulceration and potentiallower limb amputation in the diabetic population;2) develop a tissue breakdown potential index orrisk index based on these noninvasive screeningexaminations ; 3) conduct a prospective evaluationof the natural course of diabetic insensate foot ; and,4) conduct a clinical evaluation of the therapeuticeffectiveness of the VA San Francisco TherapeuticMolded Shoe.

Progress—The establishment of a multi-disciplinaryteam was accomplished through the coordination ofthe STAMP director . A comprehensive history andphysical examination was designed specifically forobtaining the most complete information relative toa patient's diabetes, vascular, neurological and bio-mechanics status . A cross-sectional study of patientsin the metabolic endocrine clinic was conducted todetermine the frequency of pathological and social

factors presenting to patients with diabetes mellitus.The VA San Francisco Therapeutic Molded Shoe

will be evaluated as to its therapeutic effectiveness.One group of patients determined to be at high riskof ulceration or limb loss will be provided both amolded shoe and sandal . A second similar group ofdiabetic patients will continue to receive the typeof care and shoe gear normally provided to them.

Preliminary Results—A cross-sectional study of thefrequency of lower extremity complications second-ary to diabetes mellitus of patients presenting to ametabolic-endocrine service has been completed.Analysis thus far has indicated that of 92 patientsstudied, 52 percent had no neuropathy or footcomplication, 32 percent had clinical neuropathywithout a history of complication and 16 percenthave had a lower extremity complication includingpedal ulceration and amputation . Further analysisof the 94-patient study is nearing completion.

There has been established a Diabetic Foot UlcerClinic in order to both facilitate and standardize amulti-disciplinary treatment plan . Such a clinic pro-vides the clinical staff the necessary tools to employthe talents of a variety of specialties at one locationand at one time . It also provides the team a methodto more thoroughly evaluate the efficacy of varioustreatment plans in a timely fashion .

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Rehabilitation R&D Progress Reports 1987

Future Plans—Prototype molded therapeutic sandals on those high-risk patients being evaluated andand oxfords have been designed but as yet not treated by the Diabetic Foot Ulcer Clinic . An ad-

evaluated. Both shoe types appear to achieve the ditional 40 patients with foot ulcers are now beinggoals of lower fabrication time and cost . The then-

followed in the clinic . Patients from the clinic willapeutic effectiveness of the shoes will be evaluated

soon be recruited into the clinical trials for the shoe.

DataGlove Semi-Automated and Function Evaluation System

Samuel Wise, M .D.Veterans Administration Medical Center, Palo Alto, CA 94304

Sponsor : VA Rehabilitation Research and Development Service (Project #XA458-R)

Purpose—Loss of hand function prohibitively influ-ences the patient, his family and society . Annualcosts due to hand impairments total $10 billion.Improvements in hand and upper extremity functionwould help the patient become more independentand more socially interactive, thus reducing theburden on the family and society.

The DataGlove will address three major problemsin treating hand impairments . These are : 1) assessingthe exact extent of the impairment ; 2) determiningthe best therapy for the impairment ; and, 3) evalu-ating the results of therapy, whether from surgeryor rehabilitation.

The DataGlove will be used to collect data frompatients with impaired function secondary to anumber of diseases, including spinal cord injuries,peripheral nerve injuries, and other impairments.After therapy, such as surgical tendon transfers, thehand motions will again be recorded and comparedto the motions that were recorded pre-operatively .

The effects of specific transfers and the benefits ofone transfer or combination of transfers over anotherwill then be analyzed . Other therapeutic modalitiessuch as hand therapy and external splints will belikewise evaluated . A library of normal hand mo-tions, impaired hand motions, and the effect ofdifferent modalities for treating the impairments canthen be created.

Thus, the goal will be to analyze "new" dataobtained from the DataGlove to determine if it willbetter guide the choice of therapeutic modalities forspecific hand impairments . In addition, it will pro-vide patient education with respect to the handimpairment they have and how it changes with anintegrated program of therapy . It will help patientsto understand what they can expect from a plannedsurgical treatment for their own impairment basedon the library of previously recorded pre- and post-operative DataGlove analyses.

A Comparison of the Effectiveness of Flexible and Rigid Shoes in Relieving Pain at the

etatarsophalangeal Joints of Rheumatoid Arthritis Patients

Paul Allard, Ph .D., P . Eng. ; Hyman Tannenbaum, M.D. ; Hubert Labelle, M.D. ; Laval Leclerc,Pediatric Research Centre, Hospital Sainte-Justine, Montreal, Quebec H3T 105, Canada

Sponsor : CARR, University of Montreal

Purpose—Rheumatoid arthritis is a systemic inflam-matory disease, characterized primarily by jointinflammation, which can lead to permanent jointdamage . The foot is involved in up to 88 percent ofcases leading to foot pain, ambulation problems,loss of independence and diminished productivityin both the home and work environment. Tradition-ally, the treatment of foot pain includes rest, med-

ication and the prescription of orthoses . The typeof shoes worn can lead to a new load distributionconfiguration and limit the effectiveness of the or-thosis . According to the authors, there is no scientificdata examining the role of the shoe material, on theload distribution beneath the metatarsal heads andmuscle activation pattern, in the estimation of theperformance of the shoe .

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Orthoties

Progress—We hypothesized that flexible-sole shoes,which provide cushioning in acute metatarsalgia,can better distribute the load on the metatarsalheads ; whereas, rigid-sole shoes, which limit met-atarsal motion, will reduce the load acting at themetatarsal heads in chronic metatarsalgia, while stillenabling good and efficient foot propulsion . Ourstudy will measure kinematic and kinetic gait pa-rameters (obtained by high speed photography) byplacing discrete load cells beneath the metatarsalheads, the lateral border of the foot and the calca-neous : by taking force-plate measurements and by

studying muscle activation patterns in patients withrheumatoid arthritis, whose footware will be variedfrom a flexible-sole shoe to a rigid-sole shoe.

The significance of the study will be to obtain abetter understanding of the factors which can becontrolled in part by the use of different shoe rigidityin the relief of metatarsalgia . Hopefully, measure-ments will be derived which could have widespreadapplication in determining which patients mightbenefit best from the purchase of a flexible or rigidshoe.

Neofrakt versus Scotchcast in the ToneReducing Ankle Foot Orthosis

C . Smith (Student), B .Sc.Hugh MacMillan Medical Centre, Toronto, Ontario M4G I R8

Sponsor : Hugh MacMillan Medical Centre Student Research Award

Purpose—This project was designed to test the

of the Neofrakt material.practicality of an alternative material (Neofrakt) inthe design of the Tone Reducing Ankle Foot Orthosis Preliminary Results—The casting procedure was(TRAFO). Present TRAFO design incorporates assessed to be more difficult with the Neofrakt thanScotchcast in the hindfoot and shank portion of the

with the Scotchcast in all cases . Problems reporteddevice. Modifications to the orthosis following cast-

in the casting procedure included an excessiveing are limited, as Scotchcast does not maintain the

material thickness and setting time, poor fit ofproperty of plasticity once it has cured .

Neofrakt casting stockinette (resulting in wrinklingon the inner surface of the device), and the leakage

Progress—The Neofrakt casting procedure required of foam through the outer surface of the Neofraktthe use of padding and cotton stockinette similar to

stockinette . Acceptable limb positioning was ob-the Scotchcast procedure. All patients were to have

tained in only one of the ten casts taken.undergone a trial fitting in order to allow the orthotistto complete fine modifications and assess pressure

Future Plans/Implications—At the present time, theareas .

research team cannot recommend the use of Neo-Patient follow-up was to take place at 2-week frakt in the TRAFO design . Problems with material

intervals for a period of 3 months, using forms that

properties must be cleared up prior to further in-would assist in the collection of data which included

volvement of Neofrakt in the casting and construe-the examination of the effectiveness and durability tion of the Tone Reducing Ankle Foot Orthosis.

The LSU Reciprocating Gait Orthosis

R. Douglas, C .O. Ph .D. (Hon.), and M. Solomonow, Ph .D.Louisiana State University Medical Center, New Orleans, LA 70112

Sponsor: LSU Department of Orthopaedics

Purpose. –The objective of this research was to

and reciprocal (swinging one leg simultaneously withprovidents suffering lower extremity involve-

push off with the contralateral leg) manner.ment wi

n orthotic means to ambulate in a safe

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Rehabilitation R&D Progress Reports 1987

Progress—A long leg brace evolved and was modi-fied over the last 10 years to meet the objectives ofthis project . The brace has—with addition to the legmembers—pelvic and thoracic supports that allowa substantial increase in balance and stability. Thehip joints are engaged to each other with a pair ofsleeved Bowden cables so that, during the swingphase of one leg, force is transmitted to the contra-lateral hip with the cable to induce hip extension,or "push off." Special locks are available at the hipand knee joints to allow the patient to sit (hip andknee flexion) and stand up in a semi-automatic mode .

Preliminary Results—To date, the brace has beenfitted to the following patient categories : cerebralpalsy (36) ; spina bifida (300) ; muscular dystrophy(60) ; and paraplegics (225) ; quadriplegics (36) ; and,osteogensis imperfecta (14).

Future Plans—Efforts are being fo , i on improv-ing the energy transmission efficiency in the hipjoint-cable mechanism with the objective of reducingthe metabolic energy consumption expended by thepatient.

Development of Design Methodology for Anterior CruciateLigament-Deficient Knee Braces

M. Solomonow, Ph .D., and R. IYAmbrosia, M .D.Louisiana State University Medical Center, New Orleans, LA 70112Sponsor : LSU Department of Orthopaedics

Purpose—The objective of this project was to de-velop design methodology of knee braces that willmeet the needs of patients with anterior cruciateligament ruptures or damage.

Progress—A large volume of clinical, physiologicaland biomechanical data relating to knee performancewas evaluated and design criteria developed for therequirements from a knee brace . Evaluation of manycommercially available braces demonstrated that

none provided a reliable anterior protectionanism to prevent tibia subluxation, althoughvalgus protection is available.

Preliminary Results—Two designs were imple-mented, one of which was also evaluated on apatient. The designs provide anterior tibial protec-tion mechanism or reduction of extension velocityto avoid sudden or fast impact on the joint . Addi-tional patient evaluation is in progress .

mech-varus-

Ambulatory Orthoses for the Severely Disabled:A Comparative Study

N. Messenger, B .Sc . ; C . Ogilvie, F .R.C.S . ; P . Bowker, Ph.D . ; DJ. Rowley, F.R.C .S.Department of Orthopaedic Mechanics, University of Salford, Salford M5 4T, UK and The North WesternOrthotic Unit, Hope Hospital, Salford M6 8HD, UK

Sponsor : The National Fund jroResearch into Crippling Diseases (Action Research for the Crippled Child)

Purpose-A great deal of interest is currently beingshown, both in the UK and elsewhere, in ambulatoryorthoses for the severely locomotor disabled . Thishas been particularly so in the UK since the recentintroduction of the Reciprocating Gait Orthosis(RGO) . However, despite the RGO having beenavailable in the USA for a number of years, verylittle published data is available, and comparativedata on alternative devices, particularly the Oswes-try Hip Guidance Orthosis, is equally scarce .

In conjunction with a parallel project aimed atdetermining the physiological benefits of an uprightposture and the psychological and sociological ef-fects of various alternative ambulatory orthoses, theaim of this project is to undertake a comparativeassessment of four types of orthosis, namely theswivel walker, "full-set" of calipers and the recip-rocating devices, the Hip Guidance Orthosis (HGO)and the Reciprocating Gait Orthosis (RGO) . A func-tional assessment of each device, and of the training

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Orthotics

of each patient, is to be based on the measurementof the physiological cost of ambulation using aparameter based on heart rate changes, the Phys-iological Cost Index (PCI), and an analysis of videorecordings to obtain the basic temporal distanceparameters of the resulting gait . It is also intendedto update an ongoing analysis of the total costs tothe health service, both of the initial prescription ofeach device and all subsequent expenditure . Addi-tionally, a procedure for monitoring the long termuse of these devices, with a view to assessing theircontribution to the everyday lives of their users, isto be initiated.

Progress—A portable heart rate and video monitor-ing system has been developed to enable PCI andvideo assessments to be carried out on location.

A large number of patients, principally adulttraumatic paraplegics and spina bifida children, havealready entered the RGO program . Each is assessedin any current device prior to training, and in their

RGO at 2, 6, and 10 weeks post-final fitting and atregular intervals of 3 to 6 months thereafter, for aslong as is practical . A similar procedure is to beadopted with patients entering an HGO program.Additionally, a small group of subjects are to beasked to use each of at least three of the devices,but including both the RGO and HGO, in a randomlyassigned serial test, for a period of 3 months each.

Future Plans/Implications—The project is still in itsinitial stages . It is anticipated, however, that theresults will, at the end of our initial period of studyin 1991, provide useful information for the profes-sionals routinely involved with the treatment of theseverely ambulatory disabled, particularly as re-gards the prescription criteria for the various de-vices . In addition, the techniques developed fororthosis assessment will be useful for the routineshort- and long-term assessment of patients seen inour orthotic clinics.

The Biomechanics of Flat-Feet Running

Zvi Raclin, Ph .D.; Evan Sherr, B .S . ; M. Acierno, B .S.NeuroMuscular Research Center, Boston University, Boston, MA 02215Sponsor : NeuroMuscular Research Center

Purpose—The syndrome of flat-feet (extreme low-ering of the arches) is quite prevalent in the humanpopulation . If left untreated, it usually causes severepain in the lower limbs, and may contribute to theincidence of injuries in patients engaged in a physicalactivity such as running . In-shoe orthoses are usuallyprescribed to counter the adverse effects of such ananatomical anomaly.

Progress—A clinical study to test the effect of the

orthoses on the biomechanics of running has beenundertaken . This study involves having subjects runover a forceplate . The patterns of foot-floor inter-action forces, measured by the forceplate, will bestudied for flat-feet runners running with and withouttheir orthoses . The study will document the effectof orthoses on the patterns of foot-floor interactionforces, and then compare this information with thepatterns produced by normal subjects.

Assistance of Upper Limb Mobility

J .F. Orr, Ph .D . ; H. Simpson, B .Sc . ; W.V . James, F .R.C.S.Rehabilitation Engineering Centre, Musgrave Park Hospital, Belfast, Northern IrelandSponsor : The Northern Ireland Prosthetic Orthotic and Aids Service

Purpose—The aim of this project is to develop a Progress—The former system of overhead supportsdevice which supports the weight of the upper limbs

has progressed from using counterweights and put-of muscular dystrophy patients, allowing residual

leys to suspend the arms, to a design using elasticmuscle strength for useful function .

cords and a lever . The geometry of the design is

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Rehabilitation R&D Progress Reports 1987

such as to provide a constant force throughout therange of movement of a lever from which the armis suspended . A simple cuff is employed to supportthe arm, which is so designed to prevent slippageat any position . The device may be fitted readily towheelchairs, and lifting force can easily be adjustedby an attendant to compensate for varying weights

of clothing . Several prototype units have been as-sembled for trials, during which final developmentwill take place while seeking a local manufacturer.

Publications Resulting from This Research

Upper Limb Weakness in Children with Duchenne MuscularDystrophy—A Neglected Problem . James WV and Orr IF,Prosthetics and Orthutics International 8 :111-113, 1984.

Development of a Powered Orthosis for Lower Limbs

H. Miyamoto; Y. Sakurai ; Y. Shimazaki ; K. TokimuraInstitute of Biomedical Engineering, Tokyo Women's Medical College, Tokyo 162, Japan

Sponsor : Office for Life Science Promotion of the Institute of Physical and Chemical Research, Agency of Science andTechnology, Japanese Government

Purpose-To obtain an appropriate gait pattern, apowered orthosis for paralyzed lower limbs is beingdeveloped that supports the patient's body andcontrols lower limb movement . As a final goal, thepowered orthosis will enable paraplegic patients towalk on level ground with a variable cadence, tostand and sit, and to go up and down a staircase byappropriate command.

Progress—Considering the results obtained experi-mentally through the preceding years, a secondprototype was designed and constructed in 1986 . Itsmain purpose was to have a powered orthosis forlower limbs of an appropriate size so that controlmethods explored in the past several years couldbe tested on paraplegic patients . The orthosis wasfabricated in C-FRP (Carbon Fiber Reinforced Plas-tic) and in thigh and femur parts ; four electrohy-draulic actuators were incorporated . These actua-tors now have digital controls, in contrast with thefirst prototype which used an analog type . Eachactuator is controlled by a single-board microcom-puter, and all of these are totally controlled by a

microcomputer. Sensory systems such as foot-switchsensors to detect plantar contact, photo encoder tomeasure relative joint angle, and posture sensor tomeasure torso inclination in sagittal and frontalplanes, are used to accomplish a stable poweredwalk.

Preliminary Results—By basic experiments on anormal subject, it was verified that this secondversion of the powered orthosis had sufficient torquefor powered walk . The orthosis itself weighs 19 .5kg, and its control wagon 68 kg, which should bemoved with the powered walk . A powered orthosiswill be realized using these two components.

Future Plans Since the first orthosis of the secondversion was successful, a second orthosis for par-aplegic patients is under construction . As these twoorthoses are identical except for geometrical size,all the control methods will be thoroughly tested onnormal subjects prior to the clinical tests . The firstclinical results will be obtained by late 1987.

Talus Control Ankle Foot Orthosis : A New Design

Kathleen Byers-Hinkley, M .S., P.T. ; Lynne Logan, M.A., P.T . ; Robert Brown, C.P.O.Special Children's Center, Inc ., Ithaca, NY 14850

Sponsor : Special Children's Center, Inc.

Purpose-This ankle foot orthosis (AFO) was de- control, and normal heel contact with shoe . Plantarveloped jointly by two physical therapists and an surface control, such as arch supports, are notorthotist . It provides dorsal support, three points of required . It has been used on 28 patients with

61

Orthotics

neurological and orthopedic needs . The principleguiding this design has been that if the talus can bealigned and held in a normal position, it is the"keystone" of the foot and will provide stability forthe rest of the foot.

Progress—An examination procedure to determineif the patient's foot is structurally sound enough tobenefit from this type of support has been developed,based on the talus neutral procedure . Gait analysisusing high-speed motion picture photography andVanguard Motion Analysis with several clients withtraditional posterior shell AFO's, barefoot, and taluscontrol ankle foot orthoses have shown variableresults . We currently hypothesize that one variableis the amount of upper extremity support requiredfor ambulation . It appears that less weight borne onthe lower extremities decreases the benefit duringgait . X-ray studies were also made to assist thefabricator to achieve better bony alignment .

Preliminary Results—Fabrication of this device re-quires different procedures for the orthotist . Thecasting method for creating the positive mold isdifferent . Fitting and trimming this orthosis varieswidely from a traditional PSA. Cost will vary withthe location and amount of experience of the fab-ricator. The first few we attempted required severalremakes . This design is now the orthosis of choicefor providing ankle and foot support in our area.

Future Plans/lmplieations—We would like to sharethis design with others in our field. We are currentlyadding more subjects to our study as well as seekingfunding to continue this work.

Publications Resulting from This ResearchTalus Control Ankle Foot orthosis : A New Design . Byers-Hinkley

K, Logan L, Brown R, Orthotics and Prosthetics, 41(3) :22-31, 1987.

Mechanics of Ankle-Foot Orthoses

Narender P . Reddy, Ph .D . ; Paul C . Lam, Ph .D.; Mark Yankee, C.O.Departments of Biomedical Engineering and Mechanical Engineering, University of Akron, Akron, OH 4432 .5;Yankee Bionics, Inc ., Akron, OH 44302

Sponsor : University of Akron

PurposeExcess rotations at the ankle-foot com-plex present a major problem in the comprehensiverehabilitation of certain stroke patients with upperand lower motor lesions . These patients have un-controlled muscle activity which may develop intothe drop foot problem . Abnormal rotations alsooccur in the case of certain ligament injuries . Ankle-foot orthoses are generally prescribed to mitigatethis problem . However, these orthoses have notbeen evaluated from a biomechanical viewpoint.The purpose of the present investigation is to studythe biomechanics of ankle-foot orthoses.

Progress—We have developed two-dimensional fi-nite element models of the ankle-foot-orthosis com-plex and studied various static and dynamic loadingconditions . We compared stress and deformationpatterns of the normal foot with those fitted withorthoses . In addition, we experimentally examinedthe strains developed in the orthosis in a walkingcycle . Strain gauges were attached to polypropylene

orthoses . The orthoses were fitted to normal testsubjects and the strains were recorded during thegait cycle . The orthosis was held in place with astrap anterior to the calf, and a shoe which held thefoot in the lower section . Principal strains weredetermined from three-element Rosett gauges withassumed values for the material properties.

Preliminary Results—Peak stresses determined fromboth static and dynamic finite element models weresimilar in magnitude . Experimental results withstrain gauges were consistent with the results offinite element model simulation . Slight geometricmodifications of the orthosis were made to eliminatestresses at undesirable points . These design modi-fications allow functional plantar flexion, reduceinstability at the subtalar joint, and facilitate heel-to-toe gait pattern.

Future Plans/Implications—While the present simpletwo-dimensional analyses demonstrate the feasibil-

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Rehabilitation R&D Progress Reports 1987

ity of using finite element models for redesigningthe ankle-foot orthoses, further examination of dy-namic conditions and more complex three-dimen-sional dynamic finite element calculations are neededin order to be able to predict the total response ofthe ankle-foot-orthosis system . Experimental strainanalysis could perhaps be done on each orthosisbefore it is fitted to a patient and should be modifiedto avoid stresses at undesirable points .

Publications Resulting from This ResearchFinite Element Modeling of Ankle-Foot orthoses . Reddy NP,

Pohit G, Lam PC, Grotz RC, Proceedings of the Interna-tional Conference on Biomechanics and Clinical Kinesiol-ogy of Hand and Foot, K.M . Patil and H . Srinivasan(Eds .), pp . 97-99, Indian Institute of Technology, Madras,India, 1985.

One More Step in Redesigning the Ankle-Foot orthosis . LamPC, Downing M, Reddy NP, SOMA, 2(1) :36-39, 1987.

Functional Treatment of Perthes Disease

C. Ogilvie, F .R.C.S . ; DJ. Rowley, B .Med .Biol ., M.D., F.R.C.S . ; T.W.D. Smith, F .R.C .S.North Western Orthotic Unit, Hope Hospital, Salford M6 8HD, England, and The Children's Hospital, Sheffield,EnglandSponsor : None Listed

Purpose—Perthes Disease re

enigma. Whilethe pathological process of is revasculari-zation and healing is well know he initiating insultor agent remains to be identified . The treatment is,therefore, still somewhat e 3 ni, if treatment isthought to be necessary . Some c thopedic surgeonstreat by "supervised neglect" with bed rest andpossibly traction for pain relief during periods ofhip irritability . However, the literature on the subjectwould suggest that containment of the femoral headwithin the acetabulum during the active and healingphases, maintains the shape of the head . A normalspherical shape may not be achieved, but a measureof congruent incongruity results between the femoralhead and the acetabulum as an acceptable alterna-tive.

Progress—Many orthoses have been produced tomaintain the shape of the femoral head . The orthoticdevices limit, to a greater or lesser extent, thefunction of the hip, while maintaining containmentby abduction . It was to maintain, as far as possible,the motion of the hip joint, to give a mh l,effect,

that the Trans Pennine Splint (TPS) was designed.This principle is similar to that of the Pavlik Harnessused in congenital hip dislocation.

The TPS consists of a polyethylene body jacket,to which the hip abduction flexion hinge is attached.The distal part of this hinge is then attached to aplastic thigh cuff and through a second knee flexionhinge to a calf cuff. These are held in place byelastic strapping with velcro fastening, It is wornthroughout the waking hours .

The children have full clinical assessment andinitial X-rays of the affected hip and a weightbearingradiograph at initial fitting to check containment,Adjustments to the abduction hinge are made asnecessary . The orthosis is worn throughout the day.During periods of irritability, bed rest has beenadvised . Follow-up weightbearing radiographs aretaken at 2-month intervals, until healing is adjudgedto have taken place, at which time the children areallowed to discard the orthosis.

To date, 22 children (19 boys and 3 girls) havebeen fitted in Sheffield, and 6 children (4 boys and2 girls) fitted in Salford. The full range of CatteralGroupings have been treated . The orthoses haveproved to be robust and have allowed most of theusual activities of this age group, though organizedgames and school physical education sessions arenot allowed.

Preliminary Results,There have been three chil-dren, with four hips involved, who have been al-lowed to discard the splint . The sphericity of thefemoral head assessed by Mose's criteria gave onefair and three good results . Clinically, three hipshad full range of movement ; one had limitation ofrotation in extension. The tolerance of the orthosisby the children has been remarkable, we believe,due to the amount of activity it allows.

Future Plans/Implications Within the next fewmonths, we hope to have more children able todiscard the orthosis . However, the true results canonly be assessed many years from now, and it isthe hope of the authors that this will prove possible .