J Korean Soc Phys Ther Vol.26, No.1, February 2014 The Journal of Korean Society of Physical Therapy plssn 1229-0475 elssn 2287-156X Original articles 안굽이및밖굽이무릎을가진젊은성인들에게서등척성운동시안쪽넓은근과가쪽넓은근의근수축개시시간차이 박설 1, 이우진 1, 박지원 2 1 대구가톨릭대학교대학원물리치료학과. 2 대구가톨릭대학교의료과학대학물리치료학과 Differences of Onset Timing Between Vastus Medialis and Lateralis during Knee Isometric Contraction on Individuals with Genu Varum or Valgum Seol Park 1, Woo-Jin Lee 1, Ji-Won Park 2 1 Department of Physical Therapy, Collage of Medical Science, Catholic University of Daegu, 2 Department of Physical Therapy, College of Medical Science, Catholic University of Daegu Purpose: The purpose of this study was to investigate how different knee alignments (genu varum and genu valgum) affected activations of quadriceps muscles with measurements of onset-time differences between vastus medialis and vastus lateralis during isometric contractions at both 30 and 60 degree knee flexion. Methods: Fifty-two adults (20 genu varum, 12 genu valgum, and 20 control) were enrolled in this study. Subjects with over 4cm distance between knee medial epicondyles were assigned to Genu varum, while subjects with over 4cm distance between ankles medial malleolus were considered as genu valgum group. Surface EMG was used to measure onset time of both vastus medialis and vastus lateralis during isometric contraction at 30 and 60 degree knee flexion. Results: The onset time of vastus lateralis was delayed in genu varum group, and that of vastus medialis was delayed in genu valgum group at both 30 and 60 degree knee flexions. Moreover, onset time difference at 30 knee flexion between muscles was larger in genu valgum group than genu varum group. Conclusion: Subjects with genu varum or valgum activated quadriceps muscles with different orders pending on flexion degrees. Therefore, when quadriceps training program were planned to prevent pain or deformities, the findings that quadriceps were activated with different orders affected by knee alignments and joint degree at which trainings were performed, must be considered. If the selective training programs of quadriceps femoris are planned to prevent pain or deformities due to poor knee alignments, these should consider the subject s knee alignment condition. Key Words: Isometric Contraction, Quadriceps Muscle, Electromyography Ⅰ. 서론 평형을방해하는근골격계의어느변화는하지근력, 척추와말초관절의 ROM 과같은하지정렬불량을포함한다. 1-5 Received Jan 22, 2014 Revised Feb 3, 2014 Accepted Feb 4, 2014 Corresponding author Ji-Won Park, mylovept@hanmail.net Copylight c 2014 The Korea Society of Physical Therapy This is an Open Access article distribute under the terms of the Creative Commons Attribution Non-commercial License (Http:// creativecommons.org/license/by-nc/3.0.) which permits unrestricted non-commercial use, distribution,and reproduction in any medium, provided the original work is properly cited. 젖힌무릎이나넙다리뼈의비틀림, 정강뼈의돌림과같은엉덩관절이나넙다리뼈또는무릎관절등하지의구조적인변형은넙다리네갈래근에영향을미칠수있다. 6,7 안굽이무릎과밖굽이무릎은대표적인이마면에서의비정상적인무릎정렬상태이며, 무릎관절뿐만아니라하지의전반적인정렬에문제를일으키는데, 이는나아가척추변형이나요통까지도야기시킨다. 8 안굽이무릎의경우안쪽으로편향된체중전달로인해안쪽구획관절염이나퇴행성관절변형, 무지외반증등을유발하는직접적인원인이될수있으며, 자세적안정성을감소시켜낙상의위험요인이된다. 9 www.kptjournal.org J Korean Soc Phys Ther 2014:26(1):9-14 9
Seol Park, et al : Gait Symmetry in Subjects with Stroke 밖굽이무릎의경우무릎뼈탈구, 무릎넙다리관절통증, 연골연화증등을유발시킨다. 10 이러한비정상적인무릎정렬상태를야기시키는원인들로는다양하나주로넙다리네갈래근의부전과같은근육의문제, 정강뼈나넙다리뼈의비틀림, 엉덩관절의변형등뼈대계의문제등을들수있다. 10 특히, Sogabe 등 7 의연구를통해무릎정렬상태에따른넙다리네갈래근의근육단면적에차이가있음이밝혀지면서이러한안굽이, 밖굽이무릎에대한넙다리네갈래근의근전도분석에대한연구가필요하다. 흔히무릎넙다리통증증후군을가진사람들의경우밖굽이무릎의형태를띠고있으며, 넙다리네갈래근중안쪽넓은근의약화와늦은발화개시시간으로인해무릎뼈의외측아탈구를동반한다. 11 따라서무릎넙다리통증증후군을가진사람들을치료하기위한방법으로안쪽넓은근을선택적으로강화시키고우선적으로수축시키도록하는운동프로그램이사용된다. Wong 12 은무릎넙다리통증증후군과안쪽넓은근의개시지연과관련된여러문헌들을비교분석해본그의연구에서안쪽넓은근의개시지연이나타났다는연구와그렇지않다는연구가절반정도라하였으며, 따라서근수축개시지연으로무릎뼈이동을의미할수없다고하였다. 이처럼무릎넙다리통증증후군의안쪽넓은근의개시지연에대한의견도분분하지만밖굽이무릎에서의안쪽넓은근의개시지연유무에대한연구는거의없으므로밖굽이무릎에서의안쪽넓은근의근수축개시시간에대한명확한연구가필요하며, 밖굽이무릎뿐만아니라안굽이무릎의경우에서도두근육의근수축개시시간에대한분석이필요하다. 한편, 넙다리네갈래근은등척성수축을통해무릎을안정시키고보호하는역할을한다. 13 넙다리네갈래근은등척성수축시무릎관절의굽힘각도에따라근전도신호가다르게나타나며, 14 이는무릎굽힘각도에따라넙다리네갈래근의무릎뼈를안정화시키는역할에대한두근육의비중이다름을의미한다. 이처럼안쪽넓은근과가쪽넓은근은무릎뼈의이동을유발시키거나안정화시킬뿐만아니라, 무릎의정렬과도관련이있으므로안굽이무릎과밖굽이무릎을가진사람들에게서안쪽넓은근과가쪽넓은근의근수축개시시간을알아볼필요가있다. 또한무릎의굽힘각도에따라두근육의근수축개시시간이안굽이무릎과밖굽이무릎사이에차이가있는지를알아봄으로써무릎굽힘각도에따른두근육의역할이무릎정렬상태에따라달라지는지를알아볼필요가있다. 따라서본연구에서는안굽이무릎과 밖굽이무릎을가진정상성인들을대상으로두개의다른각도에서등척성수축을하는동안안쪽넓은근과가쪽넓은근의근수축개시시간의차이를비교해봄으로써무릎정렬상태에따라넙다리네갈래근이어떠한영향을받는지를알아보고자하였다. Ⅱ. 연구방법 1. 연구대상본연구에서는정형, 신경외과적인병력이없고무릎관절에통증이없는만 20세이상의건강한젊은성인 52 명을대상으로하여무릎정렬상태에따라세그룹으로분류하였다. 이를위해바로선자세에서발목간거리와무릎간거리를측정하였으며, 발목간거리가 4 cm 이상인자는밖굽이무릎군, 무릎간거리가 4 cm 이상인자는안굽이무릎군, 그이하는대조군으로분류하였다. 7 피험자의일반적인특성을알아보기위해나이, 신장, 체중, Q-각을추가로측정하였다 (Table 1). 피험자들은연구목적과방법에대해충분히설명한후자발적인동의하에본실험을실시하였다. 2. 실험방법 1) 근수축개시시간의측정안쪽넓은근과가쪽넓은근의근수축개시시간을측정하기위해 8채널무선표면근전도 (WEMG-8, LAXTHA, USA) 를사용하였다. 표면전극 (Ag/AgCl 2223, 3M, Korea) 은안쪽넓은근의경우넙다리장축의 50, 무릎뼈상내측에서 5 cm 위인지점에부착하였으며, 가쪽넓은근의경우무릎위 3~5 cm 위의중앙선을기준으로외측 15 대각선방향에부착하였다. 접지전극은무릎뼈하단에서약 6~12 cm 지점의정강뼈표면위에부착하였다. 15 근전도신호의표본추출율은 1,024 Hz로설정하였으며, 13~430 Hz의대역필터와 60 Hz의 notch filter, 심전도감소필터를사용하였다. 수집된근전도신호는 RMS로계산하여정량화하였다. 근수축개시시간은등척성수축을하기전 200 ms 동안발생하는평균근전도신호보다 3 표준편차를초과하는신호가 25 ms 이상발생되는시간을연산하였다. 안쪽넓은근과가쪽넓은근의개시시간차이를구하기위해안쪽넓은근의개시시간에서가쪽넓은근의개시시간을뺀값을사용하였다. 16 10 J Korean Soc Phys Ther 2014:26(1):9-14 www.kptjournal.org
박설외 : 안굽이및밖굽이무릎을가진젊은성인들에게서등척성운동시안쪽넓은근과가쪽넓은근의근수축개시시간차이 Table 1. Anthropometric data (M±SD) Control Genu Varum Genu Valgum N (Male : Female) 20 (7:13) 20 (5:15) 12 (8:4) Age (y) 21.40 ± 1.73 21.25 ± 1.45 23.67 ± 3.22 Height (cm) 165.35 ± 8.95 164.95 ± 7.45 171.67 ± 8.51 Weight (kg) 57.95 ± 13.10 55.40 ± 8.05 67.33 ± 14.05 Q-angle ( ) 13.15 ± 1.66 18.60 ± 1.27 7.33 ± 1.53 Distance IC (cm) 0.42 ± 1.54 5.06 ± 0.75 - IM (cm) - - 6.13 ± 1.03 M ± SD: Mean ± Standard Deviation *p<0.05, p<0.01 distance: intercondylar distance of the knee in Genu varum group, intermalleolar distance of the ankle in Genu valgum Table 2. The difference of onset timing (ms) between knee joint degree during isometric contraction. (M±SD) Control Genu Varum Genu Valgum p 30 2.98 ± 0.16-4.35 ± 7.93 15.14 ± 7.58 0.00* 60 1.22 ± 1.42-6.53 ± 10.71 9.52 ± 7.21 0.00* p 0.00* 0.00* 0.00* M ± SD: Mean ± Standard Deviation *p<0.01 등척성수축은무릎각도 30 와 60 에서각각측정되었으며, 등척성수축시넙다리네갈래근에정량적인저항을제공하기위해 Biodex system IV (Biodex medical systems, Inc., N.Y., U.S.A) 를사용하였다. 피험자는 Biodex 에앉은자세로넙다리, 가슴, 발목이고정된채발목관절과묶인레버암 (lever arm) 을밀도록함으로써무릎폄동작을수행하였다. 각각의각도에서 3회씩측정하여그평균값을분석하는데에사용하였다. 2) 자료분석안굽이무릎군과밖굽이무릎군, 그리고대조군사이에서두근육의근수축개시시간의차이를분석하기위해 Kruskal- Wallis test를사용하여유의수준을확인하였으며, 사후검증을하기위해 Rank cases로변환한후일요인분산분석 (one-way ANOVA) 을사용하였다. 이때사후검증은 Tukey 와 Duncan을사용하였다. 각도에따른차이를알아보기위해 Wilcoxon rank sum test를사용하였다. 윈도우용 PASW version 18.0을사용하였으며, 유의수준은 0.05로하였다. 1. 세그룹별개시시간의차이넙다리네갈래근의등척성운동시세그룹사이에안쪽넓은근과가쪽넓은근의근수축개시시간의차이를분석해본결과 30 와 60 에서모두세그룹간에유의한차이가있었다 (p<0.01). 개시시간의차이가양의값일경우안쪽넓은근이늦게수축했거나가쪽넓은근이먼저수축했음을의미한다. 그값이 0에가까울수록두근육의동시수축이일어났음을의미한다. 두각도에서모두안굽이무릎군은가쪽넓은근이, 밖굽이무릎군은안쪽넓은근이더지연된것으로나타났다 (Table 2). 2. 각도별개시시간의차이무릎굽힘각도에따른근수축개시시간의차이는세그룹모두유의한차이가있었으며, 세그룹모두무릎굽힘각도가 60 일경우 30 일때보다더작았다. 또한밖굽이무릎군의경우무릎굽힘각도가 60 에비해 30 일경우두근육의개시시간의차이가더컸으나, 안굽이무릎군의경우 60도에서더차이가큰것으로나타났다 (Table 2). III. 결과 IV. 고찰 www.kptjournal.org J Korean Soc Phys Ther 2014:26(1):9-14 11
Seol Park, et al : Gait Symmetry in Subjects with Stroke 안굽이무릎군, 밖굽이무릎군은양쪽무릎이나발목사이의거리를측정하거나 Q-각, tibiofemoral angle을측정하기도한다. 7,17 본연구에서세그룹을무릎이나발목사이의거리측정을통해분류하였으나추가적으로모든대상자의 Q-각을측정하였으며, 그결과무릎이나발목사이의거리뿐만아니라 Q-각에서도세그룹사이에유의한차이가있는것으로나타났다. 이는안굽이무릎군의경우 9±2.3, 밖굽이무릎군의경우 19±2.3 라고한문성기 18 의연구와비슷한결과를보였다. Q-각은넙다리네갈래근각이라고도하며넙다리네갈래근에의해발휘되는외측당김의정도를말한다. 19 넙다리네갈래근의당김에의한외측치우침은무릎뼈에대한자연적인활시위힘을만들어내며, 안쪽넓은근의약화는과도한무릎뼈가쪽활주를일으켜후천적인밖굽이무릎을나타내게된다. 20 이처럼세그룹사이에서나타난 Q-각의차이는넙다리네갈래근에의한외측당김력의차이를나타내며, 이는넙다리네갈래근과무릎정렬상태사이에관련성이있다는것을의미한다. 등척성수축시안쪽넓은근과가쪽넓은근의근수축개시시간의차이는무릎굽힘각도가 30 일때와 60 일때모두세그룹간에유의한차이가있었다. 안쪽넓은근과가쪽넓은근의근수축개시시간은안쪽넓은근의개시시간에서가쪽넓은근의개시시간을뺀값으로, 그값이음의값을나타낼경우안쪽넓은근의개시시간이, 양의값을나타낼경우가쪽넓은근의개시시간이더짧았음을의미한다. 또한그차이값이 0에가까울수록두근육의동시수축이일어난것임을의미한다. 본실험결과안굽이무릎군의경우음의값을나타내어안쪽넓은근의근수축개시시간이가쪽넓은근보다더빨랐으며, 반대로밖굽이무릎군의경우가쪽넓은근이더빠르게수축한것으로나타났다. 무릎넙다리통증증후군의 Q-각은정상무릎에서보다더큰값을나타내며, 이는후천적으로밖굽이무릎을나타낼수있다. 20 증가된 Q-각은무릎뼈를외측으로잡아당기는힘이더크게작용하여무릎뼈의가쪽아탈구를유발하게된다. 11 그원인으로는안쪽넓은근의개시시간의지연이나근육의약화로무릎뼈를안정화시키거나보호하지못해발생한다. 21 Q-각의증가가나타나는무릎넙다리통증증후군의원인이안쪽넓은근의근수축개시지연이라고한많은선행연구들 15,22 의결과와같이본연구에서도밖굽이무릎군에서안쪽넓은근의근수축개시지연현상이나타난것으로보인다. 이러한결과는무릎굽힘각도가 30 나 60 에서모두나타났으며, 무릎각도와상관없이밖굽이 무릎에서는안쪽넓은근의개시지연현상이나타난다고할수있다. 이와는반대로안굽이무릎군에서는가쪽넓은근이안쪽넓은근보다늦게수축하였다. Santos 등 22 은무릎넙다리통증증후군환자들의근수축개시시간을알아보았으며, 무릎넙다리통증증후군환자들의경우가쪽빗넓은근에비해안쪽빗넓은근이지연되었음을보고하였다. 이는무릎넙다리통증증후군이후천적인밖굽이무릎을나타낸다는선행연구와미루어볼때본연구결과와일치한다고볼수있다. 이처럼많은선행연구들이무릎넙다리통증증후군환자들에게서안쪽넓은근의근수축지연을보고하였던반면, 15,22 근수축지연이나타나지않았다고보고한연구도많이있었다. 23,24 본연구는무릎넙다리통증증후군환자를대상으로하지는않았으나, 이로인해후천적인결과로나타날수있는밖굽이무릎군을대상으로하여안쪽넓은근의개시시간이지연되었음을보고함으로써 Q-각이나무릎정렬상태가넙다리네갈래근의수축기전에영향을미쳤음을알수있었다. 안쪽넓은근은생리적으로쉽게약해지기쉬운근육으로, 이러한안쪽넓은근의약화로유발될수있는통증이나손상을예방, 치료하기위해안쪽넓은근을선택적으로강화시키기위한여러중재들이연구되고있다. 25-27 본연구결과를통해안쪽넓은근의선택적인훈련프로그램은밖굽이무릎을가진사람들에게필요하지만, 우리나라인구의 90% 이상은안굽이무릎을가지고있으므로, 이러한훈련프로그램이안굽이무릎을가진사람들에게행해질경우역효과를발생시킬수있을것이라생각된다. 따라서안쪽넓은근을강화시키기위한재활프로그램을적용하기이전에무릎정렬상태와넙다리네갈래근의발화현상을간주할필요가있을것이다. 즉, 무릎정렬상태를고려하지않은맹목적인안쪽넓은근의강화프로그램을적용하는것보다안쪽넓은근과가쪽넓은근의근수축개시시간이균형을이룰수있도록해주는재활프로그램이필요할것이라사료된다. 무릎굽힘각도에따른근수축개시시간의차이는세그룹모두유의한차이가있었으며, 무릎굽힘각도가 60 일경우 30 일때보다더작았다. 이러한결과는밖굽이무릎군의경우무릎굽힘각도가 30 일경우두근육의개시시간의차이가더컸으나, 안굽이무릎군의경우 60 에서더차이가컸음을의미한다. Smillie 28 는안쪽넓은근이무릎폄마지막 10 에서선택적으로발화하며, 마지막무릎폄 10 를생산한다고하였다. 본연구에서측정된무릎각도 30 와 60 중에서는상대적으로무릎폄상태에더가까운 30 에서 12 J Korean Soc Phys Ther 2014:26(1):9-14 www.kptjournal.org
박설외 : 안굽이및밖굽이무릎을가진젊은성인들에게서등척성운동시안쪽넓은근과가쪽넓은근의근수축개시시간차이 안쪽넓은근이좀더선택적으로발화할것으로예상할수있는데, 안쪽넓은근이더늦게발화되었던밖굽이무릎군의경우 30 에서선택적으로발화되어야할안쪽넓은근이더늦게발화되면서두근육사이에개시시간의차이가 60 에서보다더크게나타난것으로보인다. 반면, 안굽이무릎군의경우가쪽넓은근보다빨리발화되었던안쪽넓은근이 60 에서도먼저발화되었거나, 60 에서먼저발화해야할가쪽넓은근의개시지연으로인해두근육사이의개시시간의차이가더크게나타난것으로보인다. 즉, 무릎뼈를안정화시키고보호하기위한안쪽넓은근과가쪽넓은근의수축기전은무릎정렬상태가불량일경우무릎굽힘각도에따라서도서로다른기전을사용한다고사료된다. 본연구의제한점은통증이없는젊고건강한성인을대상으로하였으므로, 향후임상적으로통증을호소하거나불안정한관절을가지고있는환자들을대상으로한연구가필요할것이라사료된다. 또한밖굽이무릎군에동원된피험자의수가다른두그룹의수와달랐으며, 남자의비율이더많아평균키와몸무게등의일반적인특성이달랐다. 하지만본연구에서측정된두근육의개시시간의차이는피험자들간의개시시간의비교가아닌피험자개개인의두근육간의개시시간의차이를측정했으므로, 성별의차이는없을것이라사료된다. 향후좀더통제된피험자들을대상으로연구를진행할필요가있을것이라사료된다. 뿐만아니라, 무릎의관절각도가 30 와 60 에서만측정되었으므로, 향후좀더다양한각도에서측정될필요가있을것이며, 등척성운동에서뿐만아니라동적인움직임에서의근육의활성변화를확인한다면일상생활에서의손상위험을예방하거나치료에적용하는데에도움이될것이라사료된다. 이상의연구결과로볼때안굽이무릎과밖굽이무릎은하지뼈대계의정렬이상으로인해넙다리네갈래근의발화시간에도유의한영향을미치는것으로나타났다. 또한무릎굽힘각도에따라서도안굽이무릎과밖굽이무릎사이에서로다른수축기전을가지는것으로나타났다. 본연구결과를통해무릎정렬이상으로인한통증이나변형을예방하기위해넙다리네갈래근의선택적인훈련프로그램을계획할경우무릎정렬상태를고려해야할것이라사료된다. 참고문헌 1. Lord SR, Clark RD, Webster IW. Postural stability and associated physiological factors in a population of aged persons. J Gerontol. 1991;46(3):M69-76. 1. Kim MH, Koh EK, Jung DY. Analysis of kinematic motions of first metatarsophalangeal joint during electrical stimulation of abductor hallucis muscle in subjects with hallux valgus. J Korean Soc Phys Ther. 2012;24(4):276-81. 2. Park JW, Park S. Structural assessment of spastic hemiplegic foot using the foot posture index. J Korean Soc Phys Ther. 2011;23(6):55-9. 3. Choi GH, Park KY, Byun SJ et al. A study on angular correlation between hallux valgus and 1st mpj dorsi-flexion according to work type and age of woman. J Korean Soc Phys Ther. 2011;23(5):57-63. 4. Seo JK, Kim SY. The relationship between hip abductor muscle strength and lumbar instability in patients with chronic low back pain. J Korean Soc Phys Ther. 2011;23(4):15-21. 5. Park YS. The effects of the difference of angle of the femoral anteversion on the electrical activity of the quadriceps femoris in isometric exercise. Dankook University. Dissertation of Master s Degree. 2006. 6. Sogabe A, Mukai N, Miyakawa S et al. Influence of knee alignment on quadriceps cross-sectional area. J Biomech. 2009;42(14):2313-7. 7. Kang SH, Lee WJ, Kim TY. Possible effects of applying rehabilitation program upon bowlegged undergraduates COG(Center Of Gravity) oscillation and its correction. Journal of Sport and Leisure Studies. 2009;35(2):1061-72. 8. Chae YW, Park JW, Park S. The effect of postural stability on genu varum in young adults. J Korean Soc Phys Ther. 2012;24(6):419-22. 9. Livingston LA, Stevenson JM, Olney SJ. Stairclimbing kinematics on stairs of differing dimensions. Arch Phys Med Rehabil. 1991;72(6):398-402. 10. Yip SL, Ng GY. Biofeedback supplementation to physiotherapy exercise programme for rehabilitation of patellofemoral pain syndrome: A randomized controlled pilot study. Clin Rehabil. 2006;20(12):1050-7. 11. Wong YM. Recording the vastii muscle onset timing as a diagnostic parameter for patellofemoral pain syndrome: Fact or fad? Phys Ther Sport. 2009;10(2):71-4. 12. Cristanell F, Hoser C, Huber R et al. The influence of electromyographic biofeedback therapy on knee extension following anterior cruciate ligament reconstruction: a randomized controlled trial. Sports Med Arthrosc Rehabil Ther Technol. 2012;4(1):41. 13. Han SW. A SEMG analysis of knee joint angle during close kinetic chain exercise and open kinetic chain exercises in quadriceps muscle. J Korean Soc Phys Ther. 2004;16(3):401-11. www.kptjournal.org J Korean Soc Phys Ther 2014:26(1):9-14 13
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