ABSTRACTS OF RECENT LITERATURE

By JOAN E. EDELSTEIN, P .T.Senior Research Scientist

New York UniversityPost-Graduate Medical School

Prosthetics and OrthoticsNew York, NY 10016

Abstracts are drawn primarily from the orthotics and

prosthetics literature . Selections of articles were madefrom these journals:

Archives of Physical Medicine and RehabilitationAtlas of OrthoticsJournal of BiomechanicsClinical Prosthetics and OrthoticsOrthotics and ProstheticsOrthotics EtceteraPhysical TherapyPhysiotherapyProsthetics Orthotics International

BACON R, TASHJIAN E, RICHTER K (ProgressiveOrthopedics, Inc ., Lathrup Village, MI 48076).Detachable Cast Pylon Technique for Rigid Dressingson Below-Knee Amputee Patients . Arch Phys MedRehabi/ 67 :56-58, 1986.

The rigid dressing applied immediately after amputa-tion to achieve better healing controls postsurgicaledema, reduces pain, and prevents the complications ofinactivity. A new design, the detachable cast pylon, islighter and better suspended. The design requires a rigidremovable dressing with contour conducive to weight-bearing. Initially, the patient increases distal pressure bypulling a towel over the end of the amputation limb withthe dressing in place . Then static load is applied until halfof the patient's weight is tolerated . Then the detachablecast pylon is fitted for dynamic bearing . Weightbearingincreases at a rate that the healing amputation limb cantolerate . A definitive prosthesis is ordered when thepatient can apply most of his or her weight and the limb isfully healed, and when no additional prosthetic socks

have been added for 2 weeks.Fabrication requires 60 meters of Dacron webbing

with a buckle, 4 prosthetic socks, a latex casting balloon,elastic bandage, synthetic casting material, a flat bottomSACIi foot, polyvinylchloride tubing, and hose clamp.The detachable east pylon uses the same rigid dressing forshrinking and ambulation . The weight and bulk of thedetaching mechanism is fixed to the pylon, rather than to

the rigid dressing. This system eliminates rough edges orscrews that could injure the contralateral limb or bedding.The pylon has been used successfully with 90 unilateraland 10 bilateral below-knee amputees, fitted as early as 1week postoperatively to 10 years after amputation . Threepercent of patients had tissue breakdown secondary toshrinkage at the kickpoint of the distal tibia, which wasremedied by relief of the dressing. The Otto Bockendoskeletal pylon can also be incorporated in the designand is especially useful for pylon length adjustments forthose with bilateral amputations.

BAILER A (Zurich, Switzerland) . The Biomechanics ofthe Foot . Clin Prosthet Orthot 10:8-14, 1986.

The reciprocal influence of the position of the foot,knee, and hip means that each change in position of onejoint automatically changes the other two . The femoralneck forms a posteriorly open angle of 20 degrees thatcorresponds to the 20 to 30 degree external rotation of theankle axis . During gait the pelvis rotates 20 degreesforward and the lower leg rotates inward, as does theankle axis . The foot is a triple axial joint with axesconverging in the talus . The foot acts like a vaultsupported by three arches . Main weight is first taken bythe calcaneus, then transmitted to the first metatarsal andthe fifth metatarsal . The front transverse vault enables theforefoot to take much weight and adapt to unevensurfaces. When the feet are put together, both calcaneiform a vault to stabilize the body.

Axes of both the ankle and the talocalcaneonavicularjoints become horizontal during normal growth, stabili-zing the support system of the foot . The ankle is a hingewith a diagonal axis allowing 20 degrees vertical motion.The axis of the talocalcaneonavicular joint is obliquefrom lateral posterior to medial anterior . Both articularsurfaces of the joint are congruent only in midposition,with incongruency in both eversion and inversion.Chopart's joint, comprised of the talus and navicular, andcalcaneus and cuboid, allows forefoot rotation. Lisfranc'sjoint is a collective joint between the cuneiforms andcuboid and the five metatarsals, with an oblique hinge fordorsiflexion and plantar flexion . Chopart and Lisfranc

49

50Journal of Rehabilitation Research and Development Vol . 23 No. 4 October 1 986

joints give elasticity to the foot and allow it to adapt touneven surfaces . The metatarsals form an oblique arch.Toe joints are limited spheroids, capable of sideward,upward, and downward movements . Ligaments andmuscles hold the foot. Talipes valgoplanus includescalcaneal pronation, ankle inward rotation, talar forwardand inward drop, forefoot abduction, and supination ofthe first metatarsal . Upon loading, the calcaneus givesway, but the forefoot remains flat on the ground . Instanding, more pressure is exerted medially on the rearpart of the shoe . In swing, if the heel is badly fitting, theforefoot dictates the position of the shoe with unwanteddeflection of the shoe heel from the anatomic heel,causing lateral heel strike . If the individual steps on astone, joint strain may result if the shoe counter isinadequate.

During growth the first metatarsal pronates, leading tomore arching in adults . Ligament or tissue weakness cancause the lateral arch to flatten, broadening the forefoot,subjecting the first or second metatarsal to more pressure.Instability between forefoot and rearfoot results if theinclination between the first and fifth metatarsals isexcessive . A rocker bottom on the shoe must be compen-sated by the heel to avoid a negative effect on rollover . Acushion heel absorbs shock and increases rollover . Aheel-to-toe roll sole measured radially from the knee,allows complete foot roll and protects the ankle andChopart's joint . Insoles for handicapped patients shouldbe somewhat longer to reduce tilting sideways . Withvalgus, the rearfoot should be supinated and the forefootpronated . With varus, the whole foot must be pronated.

BASFORD J, ALLEN E (Department of Physical Medi-cine and Rehabilitation, Mayo Clinic and MayoFoundation, Rochester, MN 55905) . Adaptive Equip-ment for C6 Quadriplegia : An Approach to Effective,Simple, and Inexpensive Devices, Arch Phys MedRehabil 66 :829-831, 1985.

Much adaptive equipment has been developed forquadriplegics, such as the simple universal cuff, wrist-driven prehension orthoses, and complex environmentalcontrol units . However, these items may not permit thequadriplegic to perform certain simple activities . A C6quadriplegic underwent intensive rehabilitation and wasdischarged home with dorsal wrist splints and a universalcuff, having rejected a wrist-driven prehension orthosis asawkward and clumsy . His wish to lift objects from thefloor or table, scratch himself, open pop-top beveragecans, and smoke cigarettes was not addressed by the

rehabilitation staff . At home he invented three simpledevices to accomplish these tasks . The first device is areacher, consisting of a long dowel with a commercialthree-pronged pickup tool at one end and a suction cupfor a chin rest at the other end . With the device, the

subject could lift a soft drink can . The second device is an

adaptation of a dorsal wrist splint to which are attached asliding shaft with a metal clothespin and a paper clip forholding small objects . The third device is an applianceholder consisting of a long shaft and a 6 x 6 centimeterpocket, permitting use of any top- or side-operatedappliance such as a cigarette lighter . The shaft is attachedto the pocket at one end and forced between thewheelchair cushions and sidewall at the other end.

BERGER N, FISHMAN S, KREBS D, WEBB W (New YorkUniversity Post-Graduate Medical School, New York,NY 10016) . Application of ISNY Principles to theBelow-Elbow Prosthesis . Orthot Prosthet . 39:16-20,1986.

The thin, light, cool, flexible ISNY socket has beenadapted for medium and long below-elbow amputeesand replaces the conventional double-wall rigid plasticlaminate socket. The ISNY (Icelandic-Swedish-NewYork) prosthesis consists of a thermoplastic socketconnected via volar and dorsal struts to a laminated distalportion. The frame allows for length, shape, and com-ponent attachment and is minimal in size and extent . Thefirst ISNY below-elbow prosthesis was fitted in February1984 to a 73-year-old man who had been a part-time userof his conventional prosthesis . With the ISNY prosthesis,he became a full-time wearer . Subsequently, six unilateralcongenital amputees were fitted, ranging in age from 7 to18 years who have worn the ISNY sockets for an averageof 6 months . Forearms are an average of nearly 5 ounceslighter than conventional counterparts . All subjectsindicated that the ISNY was more comfortable, lighter,cooler, and permitted sensory input when leaning on theprosthesis . Wear times increased, and the prosthesis feltmore natural, probably due to greater intimacy of fit.Three subjects disliked the appearance of the prosthesis,with its two dissimilarly colored parts . The ISNY socketwas quieter when it struck something and permittedbetter pronation and supination . All subjects emphati-cally rejected any suggestion to return to the conventionalrigid socket.

Fabrication involves vacuum-forming polyethylene orSurlyn, 1/ 8 to 3/ 16 inch thick . Lay-up for the frameincludes a sleeve of light Dacron felt, two layers of nylonstockinette, two layers of carbon fiber tape, and two

51ABSTRACTS OF RECENT LITERATURE

additional layers of nylon stockinette . The frame istrimmed so that struts are approximately 3/4 inch wideand terminate I / 8 to 3/ 4 inch distal to the socket trimline;the shorter the residual limb, the closer the proximaltermination of strut to socket trimline . The socket isattached to the frame with adhesive-backed Velcro typepile secured to the socket and hook attached to the struts.Flexible hinges are attached at conventional sites with thecross hanger strap positioned precisely at the jointcenters, over the humeral condyles.

CARROLL NC (Department of Surgery, University ofToronto, Ontario, Canada) . Wheelchairs andMobility Aids . In : Atlas of Orthotics (2nd ed .), AmerAcad Orthopaed Surgeons . Saint Louis, MO: CVMosby, 1985, Chap 23, pp . 413-439.

Functional needs and basic gait patterns that must beassessed when selecting assistive devices such as canes,crutches, and walkers are described in the chapter.Adapted tricycles and bicycles and other patient-powered vehicles, such as the spider walker and castercart, are described.

A wheelchair prescription should be based on severalissues: Is the chair primarily for indoor or outdoor use?How much assistance is needed to get in and out of thechair? What architectural barriers and outdoor problemsexist? Who is available to lift the chair into a car? What isthe car trunk and door size? The patient should bemeasured for a wheelchair when fully dressed, includingorthopaedic appliances, and should sit in a rigid straightchair with hips flexed 80 degrees, knees 90 degrees, andankles neutral . Distance from floor to seat should beincreased 5 cm to compensate for footrest elevation . Seatwidth should equal thigh width plus 5 cm. Seat depthequals distance from the back of the pelvis to the back ofthe knee minus 6 cm.

Wheelchair sizes include child, growing junior, teen,and adult . Chair types are nonfolding, rear-wheel drive,front-wheel drive, amputee, and one-arm drive . Acces-sories and parts are large wheels, handrims, small wheels,tires, brakes, caster locks, seats, back, arms and foot-plates, as well as other items such as a narrower andcommode attachment . Before final purchase, the patientshould rent the chair deemed appropriate . An operationalcheck involves noting whether the patient can wheel thechair without exertion, apply brakes, detach armrestsand footrests, maneuver with adequate facility, transfer,fold the chair, and understand maintenance.

Powered wheelchairs, special purpose vehicles such as

curb climbers and sports chairs and maintenance arebriefly described . An extensive list of manufacturers anda 20-item bibliography complete the chapter . The follow-ing chapter, by Mery Letts and associates, concernsseating the disabled, primarily in wheelchairs with inserts.

CYBULSKI 6, JAEGER R (Rush-Presbyterian St . Luke's

Medical Center, Chicago, IL 60612) . Standing Per-formance of Persons with Paraplegia . Arch Phys Med

Rehabil 67:103-108, 1986.

Performance of 10 healthy subjects was compared withthat of 4 men with thoracic spinal cord injury ; threeparaplegics used knee-ankle-foot orthoses frequently, butnot daily, and the fourth infrequently used his orthoses.Subjects stood on a triangular center-of-force monitoringplatform, which had load cells mounted at each apex tomeasure vertical force . Data were collected for periods of20 .48 seconds, primarily at a rate of 100 samples persecond . For each 20 .48 second period of data collectedthese variables were computed : mean amplitude, swaypath, mean frequency, and lateral and anteroposteriorcomponents of each quantity . Two healthy subjects stoodfor 25 minutes as quietly as possible without moving thefeet, but they could shift weight and move the upper limbsto establish a baseline . The healthy subjects stood witheyes opened and hands off parallel bars ; eyes closed,hands off parallel bars; eyes opened, hands on bars, andeyes closed, hands on bars . Paraplegics stood withorthoses and eyes opened, hands off and ankles fixed;eyes closed, hands off, and ankles fixed ; as well as handson and ankles free. They also stood with functionalneural stimulation with eyes opened and hands on.

Both groups had increased swaying with eyes closed,except for the healthy group using hands to stabilizeposture. Paraplegics showed lower sway path for condi-tions of eyes open without using hands, suggesting lessposture-regulating activity . Paraplegics have a highermean amplitude, suggesting greater instability . When theankles of the paraplegics were unlocked, subjectsincreased swaying and mean frequency . Standing per-formance was better in orthoses than with functionalneural stimulation with respect to swaying and amplitude,but frequency was lower with stimulation . The datasuggest that vision is much more important to paraplegicsthan to healthy individuals . Using the hands enormouslyimproves standing performance, especially anteropos-terior balance . Braces are superior to stimulation forstanding balance because braces provide lateral stability,and in partial lesions stimulation may mask residualsensation used for balance .

52 _a__

Journal of Rehabillhdlda Research and Development Vol . 23 No. 4 October 1986

DGKEY G (St. Benedict's Hospital, Ogden, UT 84405).Clinical Use and Fabrication of Molded Thermo-plastic Foot Orthotic Devices . Phys Ther 65:1679--

1682,1985.

A molded semirigid or rigid foot orthosis consists of aplantar shell and "postings" on the plantar surface of theshell . The shell is made from 3mm or 4mm sheetthermoplastic and extends from the heel to just proximalto the metatarsal heads . Plastic is formed on a neutralposition cast of the foot, taken when the foot is non-weightbearing. Postings are adjusted according tomeasurements taken during non-weightbearing andweightbearing examinations and by balancing the posi-tion of the foot model with the plantar shell . Postingsprovide plantar contact with the shell and the floor,eliminating abnormal subtalar and midtarsal compensa-tion. Rigid shells are relatively thin but do not deformslightly under weight bearing as do semirigid ones, whichmay be more tolerable. The orthosis is slim, durable, anduseful with overuse syndromes, tendinitis, and otherpathological states of developing and adult feet . A distalforefoot extension may be added for balance andcushion.

Foot orthoses achieve biomechanical goals such aspreventing abnormal motion, rebalancing the malalignedfoot, assisting adaptation to the ground at heel strike,aiding pushoff, maximizing hallux arid toe function, andallowing normal movement and muscle activity . Footorthotic therapy is more effective with disorders asso-ciated with intrinsic foot imbalance and are aggravatedwith weightbearing. Normalizing the biomechanicalfunction or changing plantar contact points with the floordecreases stress and pain . Rigid plastic should not be usedwith patients who are physiologically old, have rigid feet,are insensitive, have ulcerations, or have joint limitationcaused by arthritis . Low-density polyethylene, high-density polyethylene, and Coylene are easily fabricated.Postings are of sheet Birko-cork, a nylon-impregnatedcork. Forefoot extensions are made from Birko-cork,Spenco, Plastazote, or PPT. The orthosis is covered withcushioning material, leather, or Naugahyde.

Fabrication requires casting the foot in neutral positionaccording to the method proposed by the Langer Group.A thermoplastic rectangle is heated to 400-450 degrees F,and draped over the positive casting . Vacuum or manualmolding is performed . The shell is trimmed and smoothedwith a grinder, with edges flared. Birko-cork posts areapplied . The orthosis is fitted to the patient and checkedwhen he is weightbearing and non-weightbearing. The

first day the patient wears the orthosis for 2 hours, thenincreases the wear 1 hour a day.

FAIJI KNER V, CURRIE D, KEENE D, FRIEDMAN R

(University of Texas Health Science Center, San

Antonio, TX) . A Breath-Activated Switchin

Mechanism for the Electric-Powered PrehensionOrthosis: Design and Fabrication. Orthot Prosthet39:29—39,1986.

The breath-activating switching mechanism on anelectrically powered prehension orthosis provides por-table function, unlike the environmental control unit,and allows the user the personal satisfaction of using thehand. The mouth stick is another functional aid, but ispoorly accepted. Most quadriplegics are fitted with astatic orthosis, which allows the user to do some dailyactivities, but C4 and CS quadriplegics cannot accomplishmany tasks with the static orthosis or switch from oneactivity to another without assistance . The electricallypowered orthosis provides three-jaw-chuck prehension,enabling quadriplegics to perform most functional tasksneeded for desk work, daily activities, and social activities.The awkwardness of the switching mechanism, usuallypull or butterfly switches operated by shoulder orcontralateral limb movement, limits the utility of theelectric orthosis . Impaired sensation and poorly con-trolled movements interfere with use of conventionalswitches . The breath-activated mechanism, based on the"sip and puff" principle, was developed for a quadriplegicwith C5 function on the right and C4 function on the left.The device incorporates two Fairchild Ultralow differ-ential pressure sensors, sensing as little as 0 .002 psi . Themechanism was connected to the electric orthosis . Thehand wired integrated circuit board failed occasionallybecause of faulty soldering. The wired board has beenreplaced with a custom printed board . Detailed fabrica-tion instructions are provided . The mechanism requiresexpulsion of pressure introduced through the air hose byremoving the tube from the mouth, or removing the tubefrom a "T" connector . Saliva and food must not enter thetube. Nine orthoses fitted with the breath-activatedmechanism have been made . The device is much easierfor patients to learn to use than other switchingmechanisms.

FISHER LD, JUDGE GW (Bioengineering Centre,University College London SW15 5PR) . BouncyKnee: A Stance Phase Flex-Extend Knee Unit.Prosthet Orthot Int 9 :129-436, 1985.

The natural knee flexes and extends during stance

53TS OF RECENT LITERATURE

week.gonioiamp . --

ot affect asymmetry of footcont

was associated with improvementcf *

gle symmetry . Amputees preferredknee

eel! 10 and 16 degrees . No changes inthe

nh "mild be linked to the experimentalunit. ' he

id and consistent advantages ofusing

--Ibjectiye reports of comfort . Allsulj' . ;

Bouncy K nee to their conventional

'RE C, GP oTz R . J (Edwin Shaw Hospital,wiophysiologierd Ankle-Foot

? °t Orthot 10:15–23, 1986.

Low(

have traditionally depended onbior

wen as neurophysiologicalapproache

at of neurologically involvedpatients ht

The neurodevelopmental tech-niques i

– obaths have evolved to a sensori-

11101 -T

-A motor output and change

sem- -

-i lances incorporating neuro-physiologi

of inhibition and facilitation intoankle-foot

ai l e tone-reducing devices to inhibitabnormal

*,y. The new orthosis features adesign corfigi

biomechanical principlesto limit pes varus and neurophysiological princi-ples of facilitation and inhibition to obtain dynamicdorsiflexion and plantar flexion, The material should be

flexible, dui ` Y e, and retain its shape, and the orthosisshould he

-Inn by a hemiplegic.The

of polypropylene, with a three-point r

to control calcaneal varus, and afe

',il l , tendon to prevent excessivemedial aspect of the calcaneus

plantar surface of the arch facilitates1 a ''i

n ' h e lateral aspect of the solenits vastus lateralis and

1, inhibits toe flexors andgas'

The ort' signed for individuals with cerebro-vascular accident or closed head injury who have minimalor moderai pasticity, in which the foot assumes a varuspositio

-wing phase but does not persist in varusbeyond L . stance. Those with severe spasticity arecandidates their tone can be modified through handlingtechniques or inhibitive casting . Plastazote toe separatorsinhibit tone and reduce pain . Patients should have at least15 degrees passive dorsiflexion with the knee flexed.Contraindications it I ude severe spasticity, early exces-sive prom"

'caneal valgus at initial contact.The ni' 1

- 'ted to 35 patients, primarilytho i

0'7I-

r accidents, and has been worncontin ,,' - ! le c sting procedure, the technique ofmodifying the positive model, vacuum-forming, andtrimming are described.

The orthosis allows dorsifl exion when the patient risesfrom a chair and encour e sin s dynamic control of thepelvis and knees by elir floor reaction forcesinherent in rigid orthoses.

GARRET M i LUCKWILL RG (School of Physiotherapy,University Colleg- Dublin, Ireland) . Role of ReflexResponses of a

l "Iltsculature During the SwingPha

Ar &king

an. Physiotherapy 71 :47–50,1985.

Ten able-bodied subjects had pressure switchesattached to the heel and great toe, surface electrodesplaced over the vastus lateralis and semimembranous,and polarized light sensors attached to the thigh and calf.Subjects also had a light wire fixed to an ankle strap thatpermitted introduction of a sudden unexpected resistance.They walked at comfortable speed on a treadmill.Twenty-one subjee's also participated in a preliminarystudy recordi - nyographic activation patterns ofquadriceps in gait.

Quadriceps showed only a short burst of activity at theend o f

a--

ei

g of stance. Hamstrings beganactivity ,

a. Du

— remainder of the gait cycle

phase, while conveover a stiff limband gait

--absorbirwe ; ehth,

ccthe sitto areasccyciciBouncyalignment, the kmby using the Forethe torsional st iff iltorsional bushdelivery of the experimental prostheses and at weeks 2, 6,and 34 when the experimental unit was replaced by thestandard nee unit ; sments continued for 4 more

-ai i tored with polarized lightvith gaits of five non-

Iona] prostheses require vaultingin increased energy expenditureeral knee units provide shock-

n or permit slow flexion underunits, such as the Henschke-not reextend . A flex reextendelectrohydraulic experimentala patented device intended forA feasibility study established

ncy Knee . 'The unit was appliedrd Stabilized Knee fitted to six

1--knee amputees . The unit wasn ill ion times without failure. Thes installed in prostheses with goodffset from the load line determined

-at Visualisation Unit, enablingea- ascertained and the required

ed. Subjects were assessed upon

54Journal of Rehabilitation Research and Development Vol . 23 No . 4 October 1986

both muscles were electrically silent . Application of theresistance significantly advanced onset of quadriceps andhamstring activity. Angular velocities of the knee did notcorrelate with onset of muscle activity in normal swing.Demonstration of a relationship between time of appli-cation of a resistance and time of muscle activationindicates presence of a receptor organ capable ofdetecting effects of a sudden unexpected resistance toknee movement . Presence of muscle response to theresistance during swing, when normally quadriceps isinactive, suggests reflex response serving to restorenormal gait pattern . The resistance was insufficient toalter joint velocity patterns, but had significant reductionin mean acceleration, indicating disturbed velocitypattern . Pattern returned to normal, probably indicatingcontrol of joint velocity by muscle spindles . Since themuscle responded to the resistance with latency reflexthroughout swing, fusimotor activity must be flexible,programmed by the central logomotor generator . Cor-rective reflex activity leads to control of acceleration ofknee joint movement and velocity . The central nervoussystem controls inactive and active muscle, allowingexploitation of passive forces in the production ofmovement.

KAMENETZ H (Division of Rehabilitation Medicine,George Washington University, Washington, D .C.).Wheelchairs and other Indoor Vehicles for the Dis-abled . In: Orthotics Etcetera(3rd ed .), Edited by JohnB. Redford . Baltimore, MD: Williams & Wilkins,1986, pp. 464-517.

Beginning with an extensive history of wheelchairs,Dr. Kamenetz proceeds to a classification of indoorvehicles such as rolling chairs, rolling walkers, rollingstands, and rolling stretchers . Indications for such vehiclesinclude inadvisability or impossibility of ambulation.Contraindications include those pertaining to sitting aswell as fostering unwanted dependence on the wheelchair.All wheelchairs should be prescribed by a physician,physical therapist, or other professional knowledgeableabout the patient's medical condition and the field ofwheelchairs . Selection must be based on the space inwhich the chair will be used, including probable obstaclesto passage and height of tables . The average turning spacerequired by a standard wheelchair is 60 x 60 inches . Chairsizes and details of measuring the patient are reviewed.Selection also depends on requirements for comfort, thepatient's capacities, expected function, collapsibility ofthe chair, safety, appearance, and cost.

Among the types of wheelchairs described and their

indications and contraindications for each are unfoldingones, rear wheeldrive models, sports chairs, front wheeldrive, amputee, one-arm drive, and motorized wheel-chairs. Alternatives for each of the parts and accessoriesof the wheelchair are included: wheels and their acces -

sories ; supporting parts, namely seats, seat lifts, cushions,back, arms, lapboard, overhead slings, footrests and legrests; and other accessories, including narrowing devices,commode attachment, crutch and cane holder, anti-tipping devices, sliding board, and pockets and safetystraps and belts.

Other indoor vehicles receive briefer mention, such ascasterchairs, push chairs, rolling walkerstands, andstretchers . Wheelchair training, preferably from a wheel-chair user, is important so that the patient achievesmaximum safety, efficiency, pleasure and service.

KAUFMAN W, LUNSFORD T, LUNSFORD B, LANCE L

(California State University, Dominguez Hills, CA).Comparison of Three Prefabricated Cervical Collars.Orthot Prosthet 39:21-28, 1986.

Neck motion was measured on 10 seated subjects whilewearing no orthosis, while wearing the Philadelphiacollar, Nec-Lok, and soft foam collars, using an angularscale and a custom fabricated head halter with a pointer.The halter had attachments so the pointer could bepositioned to register lateral flexion and axial rotation.Without an orthosis the average arc of axial rotation was138 degrees, anteroposterior range was 100 degrees, andlateral flexion was 77 degrees . The soft foam collarrestricted axial rotation 16 percent, anteroposterior range10 percent, and lateral flexion 14 percent . The Philadel-phia collar restricted axial rotation 29 percent, antero-posterior motion 47 percent, and lateral flexion 26percent . The Nec-Lok collar restricted axial rotation 63percent, anteroposterior motion 63 percent, and lateralflexion 43 percent.

The soft foam collar demonstrated significant motionreduction compared with no orthosis, but did notimmobilize as much as the other orthoses . The Philadel-phia collar immobilized substantially better than thefoam collar, but its soft mandibular support did notcontrol axial rotation well . Its most effective control wasanteroposterior . As with the soft collar, the Philadelphiacollar also offers a kinesthetic reminder to the wearer,The Nec-Lok immobilized substantially more than theother collars in all planes. Subjects felt it to be morerestrictive and less comfortable . The Nec-Lok is popularamong paramedics because it effectively immobilizes, is

55ABSTRACTS OF RECENT LITERATURE

easy to don, has a simple design and cut-out fortracheotomy, can be stored flat, is easily laundered, ismanufactured in three sizes, and is less expensive than thePhiladelphia collar.

KROUSKOP T, WILLIAMS R, NOBLE P, BROWN J (TheInstitute for Rehabilitation and Research, Houston,TX 77030) . Inflation Pressure Effect on Performanceof Air-Filled Wheelchair Cushions . Arch Phys MedRehabil 67:126-128, 1986.

Fourteen subjects, including able-bodied volunteersand spinal cord injured patients were evaluated whilesitting on the ROHO, Gaymar Sof-Care, and Bye-ByeDecubiti air-filled cushions . A Texas Interface PressureEvaluator monitored the interface pressures and amagnahelic pressure gauge connected to an air corn-pressor controlled internal air pressure . Each cushionwas placed on a flat, hard surface and inflated to 20mmHg. The subject was positioned on the cushion andchair height adjusted to achieve 90 degrees of hip andknee flexion. The pressure evaluator was inflated, thenslowly deflated to indicate location and magnitude ofmaximum pressure which were consistently under theischii . Curves were derived for thin, average, and obesesubjects . Pressure was lowest for thin individuals, but thistrend was not consistent with comparison of interfacepressure and body weight, which illustrated no significantcorrelation between body weight and seating pressure.Other factors, such as prominence of the ischii ortrochanters, leg length and weight, wheelchair posture,and height, influence pressure.

The Gaymar cushion, comprised of three heat-sealedlayers of PVC, is extremely sensitive to underinflation;whereas the other cushions support when underinflated.For all three less sensitivity to overinflation was displayed.A narrow range of internal air pressure for optimalseating is only 6 to 8 mmHG . Overinflation is lessdangerous than underinflation for reducing interfacepressure. The effective internal pressure was 35 mm Hg.All three cushions reduced interface pressure.

KUROSAWA H, ET AL . (Veterans AdministrationMedical Center, West Roxbury, MA) . Geometry andMotion of the Knee for Implant and orthotic Design.J Biomech 18 :487-499, 1985.

Sections of distal femurs were subjected to computer-ized analysis and direct measurements, showing thatposterior femoral condyles closely fit spherical surfaces.In flexing from 0 to 120 degrees, the medial femoral

condyle moved little, the lateral moved posteriorly 17 mmwith axial rotation of 20 degrees . Symmetrical bearingsurfaces on total knee prostheses ignore the asymmetry ofthe femoral and tibial condlyes, and may jeopardizenormal ligament length patterns and muscle lever arms.External joints, such as those used in orthoses, should bedesigned to prevent abnormal rotations, especially whenorthoses are used to protect ligament injuries and repairs.

Geometrical properties of the knee were determined todefine the axis system, and motion of normal knees wasmeasured with respect to the geometrical pattern . Finally,illustrations were given of the application of motion datato implant evaluation and external joint design . Measure-ments for each bone and joint were linearly scaled tostandardize geometrical and motion data to an average-sized knee . The mediolateral width of the femoralcondyles was taken as 80 mm for the average knee.

Application of the measurements to orthoses guidesthe design and placement of joints . Fixed hinges givereasonably accurate motion if planar motion is assumed,but they do not account for axial rotation and translation.Polycentric hinges simulate changing instant centers toprovide translation but still ignore axial rotation . Move-ment of the transverse axis through the femur showsconsiderable posterior translation laterally and anteriortranslation medially . Axes are set in joints placed relativeto the transverse femoral axis so the mechanism guidesmotion of the axis relative to the tibia . An external axis inline with the femoral axis could achieve accurate motionif motion were directly along the paths calculated . Jointlaxity of 5-10 mm anteroposteriorly and 20 to 30 degreesrotationally could compensate for placement of theorthotic joint on knees of sizes different from thestandard size on which measurements were made.

MAKI BE, ROSEN MJ, SIMON SR (Mechanical Engi-neering Department, Massachusetts Institute ofTechnology, Cambridge, M A) . Modification ofSpastic Gait Through Mechanical Damping . JBiomech 18 :431-443, 1985.

An orthosis simulation experiment was performedwith a 10-year-old boy with spastic quadriplegic cerebralpalsy and two able-bodied young adults . The velocitydependence of stretch reflexes was quantified as the anklewas dorsiflexed from -20 to +15 degrees at a number offixed angular velocities . During each rotation, the resis-tive torque was measured. Experiments were performedwith the subject relaxed and exerting 20 percent ofmaximum voluntary capability for generating plantarflexion torque. Subjects were seated, and the foot was on

56Journal of Rehabilitation Research and Development Vol . 23 No. 4 October 1986

a pedal driven by a computer-controlled torque motorwith strain gauge . Subjects also wore an orthosis simu-lator, an electromechanical below-knee orthosis whichcan be controlled to exert passive mechanical loadsacross the ankle . To offset the weight of the simulator, anequal weight was strapped to the contralateral shank.Damping torque was proportional to angular velocity inseveral patterns, such as damping only during stancedorsiflexion, during swing dorsiflexion, during all plantarflexion and stance dorsiflexion, and only during plantarflexion.

In comparison with a rigid orthosis, the damped modelchanged the wearers' kinematics, reducing abnormalmidstance plantar flexion without great restriction ofdesirable ankle rotation. No differences in electromyo-grams were detected between damped and rigid bracingof the spastic subject, probably because of high level ofmuscular activity. Ideally, the damping characteristicssuiting a patient could be implemented in a light,inexpensive, attractive orthosis . Damping could beachieved by small linear or rotational dampers on anarticulated orthosis or through intrinsic damping proper-ties of the orthotic material . The best pattern, dampingduring all plantar flexion and stance phase dorsiflexion,requires sophisticated control ; whereas the simplerpatterns of damping throughout the gait cycle or onlyduring stance phase dorsiflexon did not eliminateabnormal plantar flexion without severely restrictingankle rotation. The results support the existence of avelocity threshold effect important in spastic gait.

POPE P (The Royal Hospital and Home for Incurables,Putney, London, UK). A Study of Instability inRelation to Posture in the Wheelchair . Physiotherapy

71 :124-129, 1985.

Two hundred sixty-six individuals with severe physicaldisability who tended to slump forward or arch backwardin the wheelchair were measured and used in a mathe-matical model to estimate loading of the back support ofthe wheelchair and stress in the spine . Subjects includedindividuals with multiple sclerosis, cerebrovasculardisease, cerebral palsy, central nervous system trauma,Parkinson's disease, and arthritis . Those who used fixedor reclining backrests presented a forward curvature ofthe upper trunk and head, a flat lumbar spine, andbackward pelvic tilt, frequently with extended lowerlimbs and difficulty in keeping the feet on the footplates.Maximum curvature was between T6 and T9 . The uppertrunk curved more sharply forward in those usingreclining brackets . With the backrest at a 10 degree angle,

32 percent of body weight was supported by the backrest.Those who used extensions on the normal fixed backsupport display unstable posture with the back archedbackwards from the coccyx to the head . The upper trunkrested against or on top of the backrest, the legs were

flexed under the seat, and the arms were extended . Thesesubjects had hip and knee flexion contracture . Thetheoretically derived estimates of body weight trans-mitted through the backrest are 43 percent of bodyweight supported when the occupant angle is 50 degrees.Patients tend to slide forward when the trunk is inclinedbackward more than 20 degrees, regardless of whetherthe wheelchair has a fixed or adjustable back support . Asignificant proportion of body weight is carried by thebackrest.

The wheelchair occupant who is unable to maintainthe trunk erect falls forward, pivoting at the hips. Thearms can serve as struts for support, but the occupantfatigues quickly . To prevent forward fall, hips displaceforward, so the trunk tips back onto the backrest, and theupper trunk curves forward into the characteristic C-shape. Alternatively, the trunk can arch backwards torest against the backrest, thus bringing the sacrumhorizontal, foreshortening the trunk, and lowering thecenter of gravity . Balance is less of a problem, but grossspinal curvature results . Straps are inadequate becausethey cause the limbs to twist and ride over the restraint.

RIGAS C (Medical Physics Laboratory, University oflonnina, Greece) . Active Plantar Flexion Above-Knee Prosthesis: Concept and Preliminary Design.Prosthet Orthot Int 9:141-144, 1985.

Self-energized mechanisms may replace the function oflost musculature for the above-knee amputee, particu-larly at the ankle . Lower limb prostheses, unlike upperlimb prostheses, require large amounts of energy but arenot suitable for heavy and bulky external power sources.In normal gait, about half the energy output comes fromactive plantar flexion . A self-energized unit shouldsubtract a proportional amount of energy from anotherpart of the amputee-prosthesis system by taking advan-tage of power spent to produce controlled passive move-ment and otherwise lost as heat . At the knee, the humanjoint acts primarily as a damping mechanism, which isimitated by all prosthetic knee units that transformenergy input at the knee to heat . Energy is available fromknee flexion after heel contact, knee flexion at the end ofthe stance phase, knee extension prior to heel contact,ankle plantar flexion after heel contact, and ankledorsiflexion after foot-flat. Theoretically, more than

57ABSTRACTS OF RECENT LITERATURE

enough energy can be extracted from the knee and ankleto facilitate active plantar flexion, although the procedureof energy extraction involves heat loss and the mass andmoment of inertia of the prosthetic shank and foot aresmaller than normal . The smaller the mass and momentof inertia, however, the smaller amount of energyrequired for push off . Active plantar flexion can give theamputee forward momentum, and, by contributing toknee bending at the end of stance, will relieve the hip ofpart of its work load and will make gait more symmetricaland smoother.

The preliminary design of the system consists of fourcompression cylinders, two pistons, a storage chamber,seven one-way valves, and three on-off valves . Followingheel contact, the foot plantar flexes under the action ofthe ground reaction . A piston is pulled down, compres-sing air in a cylinder and forcing air into the storagechamber . Pressure increase prevents excessive kneeflexion. After foot-flat the foot dorsiflexes, reversingaction of the piston and air . The on-off valves providecontrol of the mechanism which links the foot with theknee . Valves are triggered on when the toes begin to flex,and valves return to off position when the foot leaves theground.

ROZENDAL RH, ET AL . (Department of FunctionalAnatomy, Interfaculty of Human Movement Scienceand Education, Amsterdam, The Netherlands).Vector Diagrams in the Evaluation of Human Gait.Arch Phys Med Rehabil 66:682-686, 1985.

Healthy and hemiplegic subjects participated in a seriesof measurements involving walking on a walkwayequipped with a Kistler forceplate . Foot reaction forcesgive the clinician an impression of the pattern ofacceleration and deceleration of the body's center ofgravity . Vertical, horizontal sagittal, and horizontal trans-versal forces are discerned . Subjects were compared witha vector diagram representing performance of able-bodied individuals, indicating the dependency of steplength, age, and physical condition on the diagram . Fiveexperiments with different groups of subjects were

14111OAttliMl; 1) Z1 11,01111al pug mu, of neatly the same

height but markedly different weights ; 2) six women andfour men, all nonhandicapped, who walked with fivedifferent step lengths ; 3) 21 individuals aged 64 to 82 ; 4)10 athletic men and nine nonathletes ; and 5) 18hemiplegics.

Walking with varying step length at one speed changedthe contour of the diagram, resulting in a wider diagram.Elderly walkers showed narrower diagrams . Nonathletes

also produced narrower diagrams, walking with smallersteps . Hemiplegics produced diverse patterns, althoughshowing intraindividually consistent patterns . In manycases the function of the legs was different, with thediagram of the nonparetic leg greater than that of theparetic limb . Retropulsion of the paretic leg was greaterthan in the nonparetic one . The diagrams showedinstability and stiffness on the paretic and normal sides.

Knee flexion in stance is speed dependent . Elderlysubjects chose lower speeds with high cycle frequenciesand lower step lengths . Nonathletes also walked withshorter steps than athletes, and walked less vigorously.Part of the variance of the diagram with speed can beattributed to step length, which is influenced by bodyweight and height, leg length, and associated physicalmeasures . Vector diagrams are more sensitive thansubjective observation of gait.

RUBIN G, DIXON M (Veterans Administration Pros- ,thetics Center, New York, NY 10001) . The Use of theAFO and PTB Orthoses for Severe PES Planus . ClinProsthet Orthot 10 :24-26, 1986

A case report of a 62-year-old World War II veteranindicates a history of increasingly painful feet . Thepatient made almost complete recovery from a cerebro-vascular accident 6 months earlier . He had not had relieffrom arch supports . The talar heads were dislocatedmedially and downward, forefeet were abducted, jointmotion was restricted, forefeet were splayed with severehallux valgus bilaterally. He had worn short ankle-footorthoses (AFO), which were inefficient, although moreeffective than arch supports . He was fitted with bilateralsolid ankle orthoses and shoes and long steel springs androcker bars, with much relief of pain, although the leftside still had painful weightbearing on the talar head . Theleft orthosis was replaced by a patellar-tendon-bearing (PTB) design that was more successful . The solidankle orthosis, if combined with a rocker bar and longsteel spring, stabilizes the ankle and foot and diminishesstresses. The patellar tendon brim provides partialunweighting of the painful foot . A conventional moldedarch support is unsuitable for a severely deformed rigidflat foot.

STEINBERG F, SUNWOOD I, ROETTGER R (Departmentof Rehabilitation Medicine, The Jewish Hospital ofSt . Louis, MO 63110) . Prosthetic Rehabilitation ofGeriatric Amputee Patients: A Followup Study . ArchPhys Med Rehabil 66 :742-745, 1985.

Review of 116 lower limb amputees older than 65 wasconducted . Prosthetic prescription was contingent on the

58Journal of Rehabilitation Research and Development Vol . 23 No . 4 October 1986

absence of class III or class IV congestive heart failure, orchronic obstructive pulmonary disease, and the patient'sability to ambulate with a walker which served as acardiopulmonary function test ; patients were required towalk 20 meters without dyspnea or tachycardia, withheart rate returning to resting level within 3 minutes.Hemiplegia, especially if contralateral, and mentaldeterioration contraindicated prosthetic fitting . Pros-thetic fitting was postponed for those with knee flexioncontracture of more than 30 degrees, or hip flexioncontracture . Below-knee shrinkage was achieved with anairbag; above-knee amputees had elastic bandaging.Fitting was also postponed until foot ulcers had subsided.Below-knee amputees usually had a patellar-tendon-bearing prosthesis with SACH foot . Quadrilateral socketswith a pelvic belt and Otto Bock safety knees wereprescribed for most above-knee amputees.

Followup after a minimum of 6 months permitteddividing the group into three categories : 1) functionalwearers who used the prosthesis, the main mode oflocomotion ; 2) partial wearers who depended on a wheel-chair for trips ; and 3) nonwearers who used prostheses, if

at all, only for cosmetic reasons . Eighteen patients werenot fitted with prostheses, primarily because of pooreffort tolerance caused by congestive heart failure ; thegroup was almost equally divided among below- andabove-knee amputees, and included two bilateral

amputees . Of the 59 below-knee amputees fitted withprostheses 73 percent were functional wearers, and onlyone was a nonwearer . Half of the above-knee amputeeswere functional wearers, and a third did not useprostheses . Although no significant difference existedbetween men and women, age was a significant deter-minant of prosthetic use . Functional outcome differencebetween diabetic and nondiabetic patients was not signi-ficant . Among the bilateral amputees, the average inter-val between amputations was 2 .5 years . Approximately athird of the bilateral below-knee amputees becamefunctional wearers, a third were partial wearers, and theothers were nonusers . One patient became a functionaluser of bilateral above-knee prostheses at the age of 71,having worn a unilateral prosthesis for 13 years prior tothe second amputation .