Gait In it i at io n in a P at ie nt W ith S pa s t ic H e m iple g ia Ce re bral P al s y W ith an d W ith o ut a D y n am ic
A nk le F o ot Orth o s i s : A P ilot S tu dy
Jeon H y e - s eon , M .H .S , R .P .T ., Clau dia S en esac, R .P .T ., Elizab eth K au fm an , M .S .
D ept . of P hy sical T h er apy , Un iv er sity of F lor ida
국 문 요 약
강 직 성 편 측 뇌 성 마 비 환 자 의 보 행 기 시 에 미 치 는 동 적 단 하 지 보 조 기 의 효 과 : 사 전 연 구
전 혜 선
플로리다대학교 물리치료학과 박사과정
클 라 우 디 아 젠 색
플로리다대학교 물리치료학과 석사과정
엘 리 자 베 쓰 카 프 만
플로리다대학교 체육과학과 석사졸업
본 연구는 강직성 편측 뇌성마비 환자의 보행 기시(gait initiation)의 특성을 파악하 고, 동적 단하지 보조기(dynamic ankle foot orthosis : DAF O)가 이런 환자들의 보행 기 시에 미치는 영향을 알아보기 위하여 실시하였다. 연구대상자는 19세 선천성 강직성 우 측 뇌성마비를 가진 여자 대학생이었다. 연구대상자는 4개의 다른 보행 기시 조건에서 각 조건당 7회의 보행 기시를 하였는데, 각각의 보행 기시 조건은: 1) 보조기 없이 좌 측 하지로 보행 기시; 2) 우측 하지 보조기 착용 상태에서 좌측하지로 보행 기시; 3) 보 조기 없이 우측 하지로 보행 기시; 4) 우측 하지 보조기 착용 상태에서 우측 하지로 보 행 기시였다. 두개의 힘 판(force plate) 위에서 본인이 선택한 가장 편안한 방법과 속 도로 2 m를 걷도록 하였다. 연구대상자가 보행 기시를 하는 동안 양쪽 가자미근과 앞 정강근에 부착된 4개의 표면 전극으로부터 근 전도 신호와 보행 기시를 하는 연구 대 상의 양 발 아래 놓인 두개의 힘 판의 자료를 분석하여 체중(body weight : BW )으로 정량화 하였다. 실험결과는 각 조건마다 7회 실시된 측정값들의 평균을 이용하였다. 본 사전연구의 결과는 다음과 같다. 1. 보행 기시 전 양다리로 선 상태에서 환측보다 건측 으로 많은 체중지지를 하였으나(환측 42.57%BW , 건측 58.03%BW ) 보조기의 착용이 환 측으로의 체중지지를 향상시켰다(환측 44.46%BW , 건측 55.54%BW ). 2. 보행 기시 중 가자미근과 앞정강근의 동시수축(coactivation)이 계속되었는데 이러한 양상은 보조기의 착용 유무에 따라 크게 달라지지 않았다. 3. 힘 판에서 들어온 지면 반발력(ground r eaction for ce)의 수직 분력(vertical element, Fz)과 전후 분력(anterior - posterior elem ent , F x )을 분석한 결과, 건측 다리로 보행 기시를 할 때 보조기 착용은 가속을 촉 진시켜 역학적으로 유리하였다.
이상의 연구 결과는 보조기의 착용이 건측 다리로 보행 기시를 할 때 미치는 신경학 적, 역학적 장점들에 대한 구체적 연구의 필요성 및 근거를 제시하고, 환자들의 보행 훈련 접근에 보다 효율적인 보행방법을 소개하는데 이용될 수 있다.
핵 심 단 어 : 뇌성마비; 보행기시; 동적 단하지 보조기.
In t ro du c t i o n
W alkin g is the m ost essential fun ction of hum an being . And difficulty in w alking cau ses significant limitation s in daily life.
Gait initiation (GI) is defined as the tr an sition fr om the st an din g t o w alking . GI is char acterized in th e n orm al population (Brunt et al, 1991; Elble et al, 1994; Nissan and Whittle, 1990). During st anding , in norm als, the t onic calf mu scle contr action m aint ain s st eady st anding . GI begin s with inhibition of t onic soleu s (SL) activity follow ed by tibialis ant erior (T A ) activ ation t o mov e the center of gr avity for w ar d t o initiat e a step . Which m ean s contr action of the T A flex es the ankle upw ar d an d pulls the shin e ov er the fix ed foot . It is believ ed that the int er action of initial SL inhibition and T A activ ation is centr ally pr ogr amed.
T he det ails of n orm al GI is char act erized by the cent er of pr essur e (COP ) m oving backw ar d an d tow ar d the sw ing limb and then lat er ally t ow ar d the st an ce limb . Ju st befor e swing occur s ther e is a quieting of gastr oc - soleu s activity in the st ance limb and simult aneou s bilat er al activity in the T A . T his T A activity is r espon sible for the post erior m ov em ent of COP t ow ar d th e swing limb . T h e cent er of m ass (COM ) m ov es ant erior and t ow ar d the st ance limb (Brunt et al, 1991; Brunt et al, 1995; Ellie et al, 1994; Nis san and Whittle, 1990). A w eight shift t o the st ance limb pr ecedes r apid acceler ation of the COM. T he st ance limb contr ols m om entum once the swin g limb is unloaded.
Contr ol par amet er s an d limb loading durin g GI in per son s suffering str oke is also docum ent ed (Brunt et al, 1991). In
str oke patient s it w as dem on str at ed that ther e w as decr eased loading ov er the inv olv ed limb w ith r esult ant decr eased for ces t o g ener at e for w ar d m om entum in GI. T his appear s r elat ed t o decr eased T A activity contributing t o the acceler ation of the COM . T her e w a s also an in cr ease in GI activity of the n on - inv olv ed limb helping t o contr ol for w ar d m omentum in pr epar ation for swin g heel strike (Brunt et al, 1995).
GI has been stu died in young norm al childr en but little is known about GI in spastic cer ebr al palsy (CP ) patient s (Br enier e, 1989; Ledebt et al, 1998). Durin g GI in childr en with less than 200 day s of independent w alking ther e is an incon sis - t ent pr ogr ession of the COP backw ar d t ow ar d the heels (Br enier e, 1989). T his m ay r elat e t o their postur al in st ability or the lack of anticipat ory m ov em ent s r elated t o pr ogr ammin g of gait (Ledebt et al, 1998). T h er e is an in cr ease in anticipat ory displacem ent s of the COP a s the child ages. Accur at e tunin g of feedfor w ar d con - tr ol has been ob serv ed in childr en bet w een 4 and 6 y ear s old (Br enier e, 1989). An im - m atur e and in con sist ent patt ern of GI is ob serv ed in y oung childr en less than 4 year s of age. Dev elopm ent of a m atur e patt ern of GI is dependent on m atur ation of the nerv ou s sy st em , experien ce, an d pr actice (Ber g er et al, 1985).
T her e hav e been sev er al articles writt en con cerning gait an aly sis inv olvin g CP patient s, how ev er , nothing specific t o GI in this population is w ritt en (Lee et al, 1992;
Skr ot zky , 1983). Gait in childr en w ith spastic CP has dem on str at ed a patt ern similar t o childr en learning t o w alk . T his patt ern is ch ar act erized by coactiv ation of
ant agonistic mu scles during st ance an d decr ea sed m agnitude in gastr oc- soleu s electr omyogr aphy (EMG) activity that is poorly m odulat ed an d t onic. Lar ge r eflex pot entials at the beginning of st an ce with short lat encies h av e also been not ed. EMG r ecor ding s show no activ e dor siflex ion dur - ing swing by tibialis anterior (Ber ger , 1998; Ber ger et al, 1984). Coactiv ation in young childr en appear s t o r elat e t o poor contr ol of equilibrium . It has been ob serv ed clinically th at per son s w ith cer ebr al palsy hav e poor contr ol of equilibrium . In childr en less than 4 y ear s old, ther e is a synchr onized pattern in the hip, knee, an d ankle j oint s. Disas - sociation of these joint s occur s in childr en 4 y ear s and older . T his allow s for heel strike, for w ar d placem ent of the leg at the en d of sw ing phase and a r olling ov er the foot for pr opulsion at the end of st ance phase.
Childr en with spastic CP do not dem on str at e isolat ed contr ol of low er ex - tr emity joint s in gait . Lacking is a m at - ur ation of spin al m echanism s du e t o su - pr aspin al cent er dam age in this population .
Br aces hav e been u sed with the cer ebr al palsy population in att empt s to impr ov e gait par am et er s and pr ev ent los s of j oint m otion . T h er e is ambiguou s dat a on the benefit s of w earing orthotics. Studies hav e show n that subject s with spastic CP w earing AF O hav e impr ov ed stride len gth , decr ea sed cadence, incr ea sed v elocity , in - cr eased per cent single- limb support and r educed ex cessiv e ankle plant ar flexion when compar ed t o n o orthosis. No differ - ences in t empor al dist ance g ait char ac- t eristics, joint m otion s , mu scle timin g , or effect s on pr oxim al joint alignm ent w er e not ed in these studies (Abel et al, 1998;
Radtka et al, 1997). A study on the effect s of AF O on balance skills of a child with a learning disability dem on str at ed impr ov ed balance skills w hen abnorm al low er ex - tr emity alignm ent and biom echanics exist ed (Orner , 1994).
T he purpose of this stu dy is t o look at gait initiation in a patient w ith spastic hemiplegia CP , with and w ith out th e u se of her br ace on the inv olv ed low er ex tr emity .
Resear ch hypoth eses w er e; 1) Compar ed t o norm al GI, the subject will dem on str at e coactiv ation in the T A and SL on the inv olv ed side. 2) SL will r em ain firing on the non - inv olv ed stance limb durin g GI. 3) Compar ed t o normal GI, limb loading ov er the inv olv ed limb will be less during quiet st ance. 4) Limb loading ov er the inv olv ed limb will be less during quiet st an ce without the br ace compar ed t o with the br ace. 5) T her e will be a corr elation bet w een limb loading and the gr ound r eaction for ces on the inv olv ed limb during GI. A s limb loading is decr eased ov er the inv olv ed limb ther e will be a decr ease in the peak ant erior - post erior elem ent of gr oun d r eaction for ce (peak F x ) and the peak v ertical elem ent of gr oun d r eaction for ce (peak F z). T his will be compar ed with and without the br ace. T his will be compar ed durin g swing and st an ce on the inv olv ed limb .
M e t h o d s
A 19 y ear s old fem ale v olunt eer ed as a participant for this study . Subject s is diagnosed with spastic right hemipar esis CP . She w ear s DAF O type orth osis in her inv olv ed leg for daily ambulation . Subj ect
is an independent functional ambulator who is actively involved in college. She show ed moder at ely increased spasticity (grade 2 in Modified Ashw orth Scale) for clinical testing . T w o for ce plat es w er e m ount ed under the w alkw ay t o mea sur e gr ound r eaction for ces of both low extr emities during GI.
Mu scle activities fr om T A an d SL mu scle durin g the GI w er e r ecor ded bilat er ally by u sing four silv er chloride surface EMG electr odes . A gr ound electr ode w as placed on th e m edial aspect of the right tibia. An electr ogoniom et er w a s placed on the st an ce limb t o mea sur e the position changes of ankle j oint , and an electrical h eel swit ch w as placed under th e swing limb heel t o det ermine the mom ent of the heel strike of the swing limb r espectiv ely . In addition one foot swit ch w a s placed under th e st ance foot t o det ermine the tim e of heel off of th e stance limb . Pr oces sed EMG and amplified for ce plat e sign als w er e sampled onlin e at a r at e of 1,000 Hz by u sin g BIOT AC sy st em (Golet a, CA ).
On th e purpose of kinem atic analy sis, subject s perform an ce w as videot aped fr om her right lat er al view durin g th e wh ole t est session (th e kinem atic data is not sh own in this paper ). A right side pla stic DAF O (patient own s) w as u sed t o compar e the effect of the orthosis on th e GI.
Subj ect stood on the pr edet ermined posi- tion s of th e for ce plat es with bar e foot for each trial of all t esting condition s. She w as in struct ed t o st art w alk with norm al self - select ed speed when a light swit ch on . T he subject w as t est ed under 4 differ ent con dition s : 1) Left leg swin g without br ace, 2) Left leg swin g w ith br ace, 3) Right leg swing w ith br ace, and 4) Right leg swin g without br ace. Subject h ad 3～4 pr actice
trials befor e the t est trials for each con dition . T he sw ing limb r epr esent s a leg which st art t o t ake a st ep for w ar d and th e st ance limb r efer s a leg which m aint ain ed on the gr ound. T he subject perform ed 7 trials for each condition . T he r an domized or der of t esting condition s w as A - C- D - B.
Analog dat a signals fr om EMG electr o- des and for ce plat es w er e st or ed and dig - ized by u sing A cknowledge soft w ar e. In de- ndent v ariables w er e; 1) the u se of DAF O (w ith and without br ace condition s) an d 2) gait initiation pattern (whether right or left limb for sw ing ). T h e dependent v ariables w er e EMG activity fr om bilat er al T A an d SL, and for ce plat e dat a (F x an d F z).
R e s u lt s
F or this paper the r esult s w er e r eporting the m ean v alue of dependent v ariables for all four condition s . T he experim ent t est ed based only one subject ther efor e; n o cau sal r elation ships bet w een in depen dent and de- pendent v ariable fr om the dat a by u sing st atistical methods.
T he subject demon str at ed coactiv ation of the T A an d SL on her right ride. T her e w as bilat er al coactiv ation of the T A and SL in all condition s. T he high peak of the T A EMG activity durin g swing ph ase is con sist ent w ith the patt ern of norm al gait EMG. T he u se of br ace show ed no significant effect on th e activity of the SL durin g the experim ent . T he bilat er al activity of the SL continued t o fir e as durin g th e entir e GI.
Durin g quiet stance w eight bearing , the subject s bear s m or e w eight on the left limb v er su s the right limb for all four
t esting condition s (F ig . 1). A s dem on - str at ed in figur e 1, th e m ean v alue of F z (v ertical for ce) during quiet st an ding befor e GI for condition A w as 58.03% of body w eight (%BW ) for the left and 42.57%BW for th e inv olv ed right limb . T his dat a clearly support s the hypothesis that limb loading during quiet st ance will be asymmetrical w ith les s w eight bear ed on the inv olv ed side.
T he br ace in r elation ship t o quiet st ance w eight bearing had a positiv e effect . When w earing an orthotic on the right limb , the subject w as able t o load mor e w eight compar ed t o condition s when the br ace w as n ot w orn (F ig . 1). T he m ean v alues of F z confirm ed this fin din g . Wh en the br ace w as on durin g quiet st an ce, the m ean v alue for right limb loading in con dition B incr eased t o 44.46%BW fr om 42.57%BW th at the m ean without the br ace for th e same condition .
F igur e 2 show s the effect of the br ace on the stance limb peak F z1. T he ev ent is
lookin g at swing limb toe off and m aximum v ertical loading of stance limb . T he data illu str at es when the br ace is w orn . the right limb is able t o load a higher per cent ag e of BW (m ean = 108.24%BW ). When the right limb is in swing , the br ace has no effect on th e m ean loading v alu es which ar e 104.82%BW without the br ace an d 104.97%BW with the br ace.
F igur e 3, which illu str at es the m ax imum v alue of peak swing leg F x , show s the m aximum loadin g of the COP tow ar d swing limb ju st prior t o the start of th e swing phase. T h e dat a conclude that ther e w er e poor acceler ation for ces on the right (inv olv ed) limb when right leg w a s u sed as a swin g limb . In this condition , the br ace offer ed no impr ov ement . How ev er , when the right limb w as in st an ce limb , ther e w as a significant incr ease in th e am ount of loadin g . W earin g the br ace as the right limb w as a st ance limb offer ed m or e efficient loading than without . T he
m ean v alu e for the four condition s ar e as follow s : A . Lt . SW (26.16%BW ); B. Lt . SW w ith br ace (29.10%BW ); C. Rt . SW (4.01%BW ); and D. Rt . SW with br ace (3.99%BW )
T he st ance peak Fx 1 (St ance limb ) v alu e w as m easur ed an d corr esponded with the swing t oe- off pha se with th e gait cycle.
T he dat a show ed that when the right limb w as in st ance phase with the br ace and
left limb w as in swin g the subject exhibit s a m or e efficient mean loading per cent age (49.37%BW ) compar ed to 40.56%BW when not w earing the br ace. T he subject r eached her maximum loadin g w hen gait w as initiat ed with the right limb while w earing the br ace (m ean =49.53%BW ). T he condition wher e th e subj ect u sed her left limb t o initiat e gait without th e br ace dem on str at ed the poor est acceler ation for ces.
F or the v ertical for ces m easur ed as F z durin g the swing ph ase, the data show s that maximum loadin g of the swing limb prior t o t oe- off w as achiev ed when the inv olv ed limb w as w earin g the br ace (m ean =84.79%BW ). Without the br ace th e loading per cent age decr eased slightly t o r eport a m ean of 81.38%BW . How ev er , when the inv olv ed limb w as u sed t o initiat e gait ther e w as a m arked decline in the ability to load the limb prior to t oe- off.
Ev en with th e br ace th e m ean loadin g per cent ag e w as 63.04%BW . T he m ean per cent ag e dr opped t o 60.03%BW when the br ace w as not w orn .
T he st an ce limb peak F z2 an d peak F x 2 dat a w er e an illu str ation at the point of double limb st an ce phase of gait . T he swing limb w a s appr oaching heel strike wher eas th e st ance limb w as pr eparing for t oe off. When th e right st ance limb w as m oving t ow ar d t oe off, the acceler ation for ces w er e impr ov ed while w earing the br ace. T he m ean v alues of peak Fx 2 w er e 77.60%BW without the br ace an d 87.90%
BW with the br ace. T he peak F z2 gr aph clearly show s that the br ace has n o significant effect on the v ertical for ces.
T he m ean v alue calculat ed for F z2 w er e 94.47%BW without the br ace an d 92.55%
BW while w earin g th e br ace.
D i s c u s s i o n
T he subj ect , while in quiet st an ce, exhibit ed a symm etrical loading with m or e w eight placed on the non - inv olv ed limb . T his is an ex pect ed ev ent with spa stic hemiplegia . W hen the br ace w a s intr oduced the subject g ained mor e st ability an d w a s able t o loa d m or e efficiently on the in - v olv ed side cau sing a shift of w eight t o the right . Ov er all, the w eight w as still prim arily shift ed t o the non - inv olv ed side.
T he SL EMG activity n ev er quiet s dur - ing entir e GI. T his is abnorm al becau se ther e should be a typical inactiv ation of the post erior leg mu scles during the swin g phase of GI. T his kind of coactiv ation patt ern w as expected fr om the subj ect due t o h er diagnosis. Resear ch has sug gest ed that this occur s fr om poor contr ol of equilibrium . T h e r esult of this pilot study show ed that the br ace did n ot hav e any significant effect on decr ease of abnorm al SL activity during swing .
T his paper r eported that while th e subject u sed her inv olv ed limb for st an ce, she w a s able t o lead m or e body w eight on the inv olv ed limb . T his fin din g support s the conv entional in struction s for gait tr aining that ther apist hav e u sed in the clinical settin g . T her apist s hav e en cour aged patient w ith asymm etries t o initiat e gait with their non - inv olv ed limb becau se then they will load mor e on the inv olv ed side.
T he u se of the br ace w as m ost effectiv e in impr oving the m ax imum am ount limb loaded and also incr easin g th e acceler ation for ce while the inv olv ed limb w as m aint ained in the st ance ph ase. T he data , how ev er , does not sh ow any significant eviden ce that it impr ov ed loadin g or
incr eased peak gr ound r eaction for ces w hen the inv olv ed limb w as u sed as a swing limb .
It appear s the w earing the br ace impr ov es gait efficiency . T he subj ect w as able t o est ablish gr eater stability while in st ance. Without the br ace, the left leg mu st shift t o the load phase quickly becau se the inv olv ed limb lack s the ability t o bear th e w eight w ith out orth otic support . T his pilot study pr ovides the necessity of further w ell structur ed clinical r esear ch t o explain th e det ails of possible mechanical an d neur o- phy siological adv ant ages of u se of br ace in GI of per son with spastic hemiplegia CP .
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