DECEMBER, 1971 P H Y S I O T H E R A P Y Page 3 Modular Lower Extremity Prosthetics ]. F O O R T , fo r m e r ly Technical D irector M anitoba R ehabilitation H ospital Prosthetics an d O rthotics Research a nd D evelopm ent U nit, W innipeg, Canada. A new term is e n te rin g p ro sth e tic s. T h e term is " M o d u la r ” . A m o d u la r p ro sth e sis is o ne w hich c a n be assem bled to a high degree from p re fa b ric a te d p a rts a n d can be ad ju ste d on the a m p u te e very ra p id ly to b ring it to o p tim u m function. C linical services at the M a n ito b a R e h a b ilita tio n H o s p ita l in W innipeg, C a n a d a , w ere the first to e m p lo y m o d u la r p ro s­ thetics o n a ro u tin e basis a n d th is has been g oing on since 1965. D e v e lo p m e n t o f the m o d u la r system fo r low er ex­ trem ity a m p u te es w as c a rrie d o u t on a n e v o lu tio n a ry basis using w hat engineers h ad learned in th e design a n d clinical testing o f devices o f this so rt p rio r to 1965. T h e W innipeg system used n o t o nly c u rre n tly availab le h a rd w a re , how ever, b u t h a rd w a re designed in W innipeg to fill in the gaps which blocked use o f m o d u la r p ro sth e tic s up until then. T h e aim w as to b rin g in to being a co m p re h en siv e system for low er e x tre m ity a m p u te e s w hich w ould utilize existing c o m p o n e n ts a n d in tro d u c e w h a t new designs were necessary to m ak e the m o d u la r system w ork clinically. D esign o bjec­ tives w ere to develop needed c o m p o n e n ts so th a t a bare m inim um w ould be re q u ire d . T h e e v o lu tio n a ry process used to develop th e system w as based on m eeting a n y o f the needs in the re h a b ilita tio n system w hich w ould reduce delays a n d in te rru p tio n s to re h a b ilita tio n p ro g ram m es even if usefulness w ere lim ited to o nly p a rts o f the p ro g ram m es. T hus, in th e beginning, p re fa b ric a te d so ck ets w ere used with c o n v entional te m p o ra ry p ro sth e se s so th a t b o th c o n d itio n in g o f the stu m p a n d tra in in g o n a p ro sth e sis co u ld be carried o ut sim u lta n eo u sly ra th e r th a n seq u e n tially as was p re ­ viously the case. A t first, so c k e ts fo r a b o v e the knee a m p u ­ tees were p u t in to service. F o u r so ck ets left a n d right were used, these being a d ju s ta b le in g irth a n d v a ry in g in size so th a t as stu m p m a tu ra tio n p ro c ee d ed , th e so ck ets c o uld be adjusted tighter a n d , w hen th e full range o f a p a rtic u la r socket h a d been used up, the a m p u te e c o uld be tran sferre d to a sm aller size to c a rry on w ith c o n d itio n in g a n d training. Over the p ast seven y ears a lm o st 200 cases w ith a m p u ta tio n th rough the thigh have received th eir early train in g and c o n d itio n in g w ith these te m p o ra ry a d ju s ta b le p lastic lam in ­ a te sockets. Since th e n c o m p a ra b le te m p o ra ry sockets have been designed a n d used extensively on B /K a m p u te es five I socket sizes, left a n d rig h t, satisfying the needs o f the bulk o f new B /K a m p u te es being re h a b ilita te d in W innipeg. L im ita tio n s o f these devices led us qu ick ly in to the design o f a lte rn a tiv e c o m p o n e n ts. A single axis k n e e-sh a n k u nit, which in c o rp o ra te d the B erkeley P n e u m atic Sw ing P hase C o n tro l C ylinder a n d a w edge-disc alig n m en t co u p lin g , were designed and w ere so o n sufficiently useful to serve as tem ­ po rary devices fo r B /K a n d A /K a m p u te es. A lth o u g h they were initially re stric te d fo r use to in -p a tie n ts, designs soon becam e d e p en d a b le e n o u g h to use on o u t-p a tie n ts. Finally, the devices were sufficiently reliable fo r use in the final o r definitive lim b. T h e n it w as possible to in itiate a m p u te es into their re h a b ilita tio n p ro g ra m m e s early w ith devices which w ould serve them th ro u g h all phases o f re h ab ilita tio n , including the p o st-re h a b ilita tio n phase. A hip fo rk was designed to p e rm it c o n s tru c tio n o f a m o d u la r p ro sth e sis for nip d isa rtic u la tio n a m p u te e s a lso . T h e th ree types o f pros- these are now availab le for all stages fo r B /K , A /K a n d H /D am putees. T h e alig n m en t co u p lin g , called the W edge-D isc- A lignm ent U n it, could be used a t different levels in a ny o f ^ three c ategories o f p rostheses. S A C H feet were used in all because they a re well sta n d a rd iz e d a n d p rovide a d e q u a te ju nction. T he H ip D isa rtic u la tio n a m p u te e s use the sam e Knee-shank u nit as the A /K a m p u te e s, and th e N o rth - W estern U niversity H ip J o in t is used, a device w hich is single axis a n d h a s alig n m en t a d ju s ta b ility b u ilt in to it. T h u s it can be seen th a t only th ree elem ents had to be designed to m ak e the system w o rk a b le fo r these three levels o f a m p u ta tio n ; the W in n ip e g Single Axis K nee- S hank U nit, the W edge-D isc A lignm ent U n it a n d the W innipeg H ip F o rk . R ecently, a knee d isa rtic u la tio n unit has been designed w hich is now being in tro d u c e d for clinical testing. F u rth e r, redesign o f the Berkeley P n e u m atic Sw ing P h a se C o n tro l U nit h as been c o m p le te d to im p ro v e reliability, sim plify m a n u fa c tu rin g , a n d to reduce w eight. Im p ro v ed S A C H feet have also been designed. T he final version o f the S A C H foot designed in W innipeg has a m etallic heel a n d po ly ­ u re th a n e re in fo rc em e n t o f the fo o t a ro u n d the heel to increase d u ra b ility o f the foot. A t the ankle, the sh a p e s o f the feet a re so org a n iz ed th a t a m in im u m n u m b e r o f shapes p erm it eco n o m y in the design o f p re fa b rica ted c osm etic covers o f flexible p o ly u reth an e . A S SE M B L Y O F A W IN N IPEG Fig. 1(a) Modular B/K Prosthesis with Wedge-disc Align­ ment Units, a S A C H foot and patellar suspension. R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) Page 4 P H Y S I O T H E R A P Y DECEMBER, 1971 It is co sm etic re s to ra tio n , a lo n g w ith n o n -a d ju s ta b ility o f a lig n m e n t th a t h a s been th e stu m b lin g block to th e in tr o ­ d u c tio n o f m o d u la riz e d p ro sth e se s in to clinical services. F o r th e W innipeg system fo u r cosm etic c o v er m o u ld s were m ad e w hich co u ld be m atc h ed to six right a n d six left feet, giving th e system o n e s ta n d a rd c a lf sh a p e fo r cosm etic re s to ra tio n o f p ro sth e se s fo r th e B /K a m p u te es. T h is single sh a p e h as a d e q u a te ly m et the needs o f a p p ro x im a te ly 30 per c ent o f th e 300 a m p u te e s p ro v id ed w ith m o d u la r B /K prostheses. P ro g ra m m e s to d e velop a g re a te r ra n g e o f shapes a re c u rre n tly u n d e rw ay fo r b o th th e W innipeg m o d u la r system a n d o th e r m o d u la r system s such as the B O C K a n d B L A C H F O R D system s being in tro d u c e d in G e rm a n y a n d E n g la n d . A m e ric an d e v elo p ers a re also m ak in g g o o d head w ay in th e de v elo p m en t o f cosm etic covers w hich c an be a d a p te d to th e C a n a d ia n a n d British system s as well a s th e A m e ric an system o f m o d u la r p ro s­ theses now in design. As a n a lte rn a tiv e , p ro sth e se s w hich d o n o t fall w ith in th e cosm etic re sto ra tio n system s c u rre n tly availab le, co v ers a re m a d e o f po ly este r p lastic lam in ates fa b ric a te d o ver sc u lp tu re d rigid p o ly u re th a n e fo a m cast a r o u n d th e pylon stru c tu re s, o r ov er p re fa b ric a te d blan k s o f rigid p o ly u re th a n e w hich a re sc u lp tu re d . T h e plastic shells o b ta in e d a re se p a ra te d from the foam a fte r fa b ric a tio n fo r in sta lla tio n on th e m o d u la r lim bs. In W innipeg the th ig h sections o f hip d isa rtic u la tio n p ro sth e se s a re covered w ith a tru n c a te d c o n e o f sp o n g e ru b b e r c overed with lea th er. A lth o u g h soft covers have been d e signed fo r the kn e e-sh a n k u n it, th e b ulk o f th e A /K a m p u te e s receive thin plastic la m in a te shells fo r d ressing up th e ir prostheses. A c ru cial fa c to r in m o d u la r p ro sth e se s is th e c a p a c ity to qu ick ly e x change sockets. D e te rio ra tio n o f so c k e t fit due to s tu m p sh rin k a g e h a s lo n g been a so u rc e o f tro u b le for a m p u te e s o f a ll levels. T h e new a m p u te e s w ho pass th ro u g h th e ty pical re h a b ilita tio n services a re especially p ro n e to s tu m p sh rin k a g e, o ften re q u irin g tw o o r th ree so ck ets w ithin th e first y e a r a n d a f u rth e r c h an g e a fte r th a t. In W innipeg a receptacle system is used to c o n n ec t th e so c k e t to th e rest o f th e pro sth e sis. T h e receptacles c u rre n tly being used are m ad e on a c u sto m basis. B efore th e socket is com p le te d a p la ste r e x tension is c ast o n to th e e n d o f it a n d a plastic shell fa b ric a te d w hich in tim ate ly fits th e m o re p roxim al p a rts o f the socket a n d fills o u t th ig h sh a p e fo r th e A /K a m p u te e s, o r is ta ilo re d d o w n for easy c o n ta in m e n t w ithin th e cosm etic c o v er fo r th e B /K a m p u te e s. T h e base o f a rece p ta c le is m ad e flat a n d a t th e c o rre c t a lig n m e n t angle fo r a tta c h m e n t o f th e rest o f th e c o m p o n e n ts. T h e system w o uld be im p ro v e d if p re fa b ric a te d a tta c h m e n t b rack ets w ere designed to link th e socket on to th e rest o f th e p ro s­ thesis. F o r H ip D isa rtic u la tio n a n d H em i Pelvectom y a m p u te e s n o receptacle is re q u ire d . F o r th e knee d isa rtic u ­ la tio n a m p u te e th e re ceptacle is being designed to fo rm an in te g ral p a rt o f th e knee so th a t the socket c an be plugged in to o n e w hich is o f th e c o rre c t size. T h e B /K p ro sth e sis c o n sists o f a S A C H fo o t w ith a W edge- disc A lig n m e n t U n it b o lte d o n to it, a piece o f tu b in g to m a k e u p sh a n k length, a second W edge-disc A lignm ent U n it b o lted o n to th e socket re ceptacle a n d th e socket plugged in (Fig. 1). T h e A /K p ro sth e sis c onsists o f a S A C H fo o t a n d W edge-disc A lignm ent U n it, th e W innipeg K nee- s h a n k U n it, a second W edge-disc A lignm ent U n it betw een th e knee a n d th e receptacle, a n d th e re ceptacle w ith the so c k e t plugged in (Fig. 2). T h e A /K p ro sth e sis a lso h as a c la m p -o n valve h o u sin g fo r use w ith a H o s m a r su c tio n socket valve. W h e n belts a re used fo r su sp en sio n , a tta c h ­ m en ts a re m ad e to th e receptacle leaving th e so c k e t free. Sockets a re b o n d e d to receptacles in th e final process o f c o m p le tin g th e lim b. T h e H ip D is a rtic u la tio n P rosthesis c onsists o f a S A C H fo o t, W edge-disc A lig n m e n t U n it on th e fo o t, tu b in g to m a k e up sh a n k length plugged in to the W innipeg Single A xis K n e e-sh an k U n it, a W edge-disc A lig n m e n t U n it w ith tu b in g a d a p te r, tu b in g to m ak e up th ig h len g th , th e W innipeg H ip F o r k w ith a th ird W edge- disc A lignm ent U n it b o lted o n , th e N o rth w e s te rn U niversity H ip Jo in t, a n d th e socket b o lte d on to th e h ip jo in t. Fig. 1(b) The same type o f prosthesis on a B/K amputee, with supracondylar suspension. T h e K n e e D is a rtic u la tio n p ro sth e sis c onsists o f a S A C H fo o t, w ith a W edge-disc A lignm ent U n it a tta c h e d , sh a n k tu b in g plugged o n to a second W edge-disc A lig n m e n t U n it w hich b o lts to th e c ast a lu m in iu m u p p e r sh a n k section, the u p p e r sh a n k se ction w ith side a rm s dov e ta ile d a n d set- screw ed. T hese fit in to clevises la m in a te d in to the knee- re ceptacle section. T h e socket plugs in to th e k n e e-receptacle u nit. T h e knees a re p n e u m a tic ally c o n tro lle d fo r th e K nee D is a rtic u la tio n , A /K , a n d H ip D is a rtic u la tio n level p ro s ­ thesis. C o n v e n tio n a l su sp en sio n system s a re used. T o d a te , o v e r 300 B /K a m p u te e s have been p ro v id ed w ith m o d u la r p rostheses in W innipeg. A p p ro x im ately 150 A /K a m p u te e s have received them . A b o u t tw o d o z e n H /D a m p u te es use them . N o knee d isa rtic u la tio n a m p u te e s have yet been fitted w ith th e e n tire system w o rk e d o u t fo r them , a lth o u g h h a lf a do zen a re w earing a p re lim in a ry design w hich includes B O C K side jo in ts , p lastic la m in a te h o u sin g s fo r th e a tta c h m e n t o f th e low er side a rm s, a n d th e p n e u ­ m atic sw ing p h a se c o n tro l u nit. W h en u p p e r s h a n k sections a re a v a ila b le these will be p hased in to clinical services. T h e fu tu re o f m o d u la r system s is a ssu re d fo r low er ex­ trem ity a m p u te e s a n d th ere is no re a so n to d o u b t th a t such system s will be dev elo p ed fo r a rm a n d o rth o tic p a tie n ts. U se o f m o d u la r p ro sth e sis will e x p a n d a s the cosm etic re s to ra tio n p ro b lem s a re b e tte r solved. M e a n ­ while, th o se system s w hich have been p ro v e n o u t clinically sh o u ld be used fo r cases a n d re h a b ilita tio n processes w hich c an g ain fro m them . P e o p le inte rested in b rin g in g m o d u la r­ iz a tio n in to clinical services w here th ey have n o t been used R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) DECEMBER, 1971 P H Y S I O T H E R A P Y Page 5 Fig. 1(c) A Supracondylar type o f prosthesis cut away to show details o f construction: S A C H foot, Pylon unit, receptacle for the socket and the socket plugged in. befo re sh o u ld in tro d u c e th em fo r h a n d lin g th e ir new a m p u te e s w ithin th e re h a b ilita tio n setting. As confidence a n d c o m p e ten c e d evelop, they c an , as we did, e x te n d the ra n g e o f a p p lic a tio n until all clinical cases can be ad eq u a te ly d e alt w ith using m o d u la r c o m p o n e n ts fo r every p h a se o f care. L o o k in g a h e a d to w h a t can be expected o f w ell-developed m o d u la r c o m p o n e n ts, these p re d ic tio n s can be m ad e on the basis o f W innipeg experience. R e h a b ilita tio n tim e will be red u ced by a p p ro x im a te ly 50 per cent. N o t all o f th is is d ue to m o d u la riz a tio n how ever. O th e r fa c to rs in clude early in itiatio n o f re h a b ilita tio n , g re a te r fa m ilia riz a tio n w ith m o d ern a m p u te e h a n d lin g p ro c e d u re s a n d closer c o n tro l over m an a g em e n t o f th e a m p u te e d u rin g th e early phases o f care. B ut, no d o u b t, b ased on experience gained at W innipeg, it can be safely said th a t a t least a 30 per cent re d u c tio n in service tim e can be a ttrib u te d to th e speed a n d facility w ith w hich a d ju s tm e n ts in a lig n m en t, a d ju s tm e n ts in length a n d socket re p la ce m en ts c a n be c a rrie d o u t. T he system re p o rte d here m akes it easy for th e p ro s th e tis t to p rovide p rostheses q u ickly as p a tie n ts e n te r th e re h a b ilita ­ tio n stre am . (M o d ifica tio n s in alig n m en t a n d length can be c arried o u t rig h t in clinic if necessary.) M o d u la riz a tio n will p e rm it th e d e v elo p m en t o f highly c en tralized m a n u fa c tu rin g a n d assem bly o f pro sth e se s by technicians fam iliar w ith th e system fo r delivery to the re h a b ilita tio n scene w ith in a c o u p le o f days. C osm etic re sto ra tio n , c u rre n tly less th a n a d e q u a te , m ust be b ro u g h t to a b e tte r sta te if fu rth e r tim e gains a re to be m ade in p re p a ra tin g pro sth e sis. A lso a linking system b e tte r th a n th e receptacles c u rre n tly used w ould speed up fa b ric a tio n . C u rre n tly , fa b ric a tio n tim e w ith th e W innipeg system is a p p ro x im a te ly h a lf th a t re q u ire d for c o n v e n tio n a l prostheses. If a m e th o d w ere d e v eloped by w hich socket a n d leg sh a p e co u ld be defined num erically, th e tim e -co n su m in g processes c u rre n tly used for these tw o aspects co u ld be reduced, b u t, m ore im p o rta n t, g re a te r sy ste m atiza tio n a n d sta tistica l m ate ria l a c c u m u la tio n w ould lead to sta n d a rd iz a ­ tio n o f m an y shapes no w m ad e by la b o rio u s h a n d c raft m eth o d s. Such a system involves th ree d im e n sio n a l shape sensing a n d re p ro d u c tio n . A n e xam ple m eth o d o f sensing is p h o to g ra m m e try . A n o b ject is p h o to g ra p h e d sterio- g raphically, distan ces betw een surface p o in ts a n d a reference system a re defined in num erica l term s. T h e d a ta c a n then be used to p ro g ra m m e n u m erically c o n tro lle d c arv e rs w hich c a n p ro d u c e th e sh a p e direc tly , in m irro r im age, sm aller o r larger, on c o m m a n d . S uch m ec h an iz atio n , c e n tra liz a tio n , m o d u la riz a tio n a n d th e de v elo p m en t o f m o re m o d ern to o ls fo r th e p ro sth e tist to use a t th e clinical scene (such as an electrical alig n m en t u n it, designed in W innipeg, w hich c a n be used by e ith e r p ro sth e tist o r a m p u te e to alig n a fo o t w hile th e a m p u te e w alks) sh o u ld lead to th e p ro sp e ct o f h a ving th e p re scrip tio n fo r a p ro sth e sis filled w ith in a day o r tw o o f p re sc rip tio n , a p rosthesis sufficiently a d ju s ta b le in a ll im p o rta n t features to p erm it the p ro sth e tist to b rin g it in to o p tim u m fu n c tio n , a n d m a in ta in it so, very qu ick ly a n d easily. Fig. 2. Assembly o f a Winnipeg modular A/K prosthesis with temporary socket for early training and conditioning o f an A/K amputee. R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. )