. however , in fact , it increases 
 efficient contact surface between femur and tibia and minimizes loads per unit area to 
 decrease contact pressure to articular cartilage1 .
meniscal injury causes knee extension block in daily life as a 
 characteristic finding , pain , limping gait , crepitus and giving way during stair or gravel 
 gait1 , 2 .
in addition , knee joint stiffness because of locking leads to 
 limitation of motion .
therefore , remarkable atrophy in vastus medialis oblique ( vmo ) among quadriceps femoris 
 occurs without exception2 .
muscular 
 imbalance of vmo with vastus lateralis ( vl ) and delayed muscle onset time during knee 
 extension generate excessive lateral movement of patella3 .
change in pathway of patella during movement causes excessive loads 
 on subchondral bone4 , 5 .
instability of knee joint can change neuromuscular control system of lower limbs followed 
 by abnormal changes in core muscles that control hip joint such as gluteus maximus ( gmax ) 
 and gluteus medius ( gmed)6 .
gmed 
 malfunction and decreased muscle activity cause adduction and internal rotation in hip joint 
 during weight bearing while walking7 , 8 . like in the case of vmo weakness , this 
 increases q - angle , causes genu valgum and moves patella to lateral side to increase valgus 
 vector9 .
therefore , importance of vmo strengthening and selective strengthening of gmed should be 
 emphasized to consistently improve symptoms of knee joint meniscal injury9 , 10 . 

however , recent studies relating to knee joint rehabilitation after meniscal surgery only 
 analyzed comparison of muscle activity ratio between vmo and vl or muscle activity of 
 gmed . therefore , this study analyzed the effect of improvement in muscle strengths of both vmo 
 and gmed after meniscal surgery on knee joint function index and pain to provide effective 
 and useful information for the physical therapeutic treatment .
this study selected sample of 26 patients who were aged from 20 to 40 , diagnosed with 
 meniscal tears and had meniscal surgery .
the patients were 
 understood the purpose and procedure of this study , exercise period etc . and provided 
 written informed consent prior to participation according to the ethical standards of the 
 declaration of helsinki .
table 1table 1.general characteristics of the subjectsgroup i(n=8)group ii(n=9)group iii(n=9)gender ( male / female)6/26/37/2age ( years)30.6  6.630.2  631.6  6.2height ( cm)167.7  4.6166.6  6.8167.6  5.3weight ( kg)66.9  12.458.8  9.865.3  11.4mmt ( 05)3.3  0.53.2  0.63.1  0.6mean  sd .
the selection criteria for 
 the participants were as follows ; ( 1 ) meniscal surgery more than 4 weeks ago , ( 2 ) no knee 
 joint rehabilitation experience , ( 3 ) the lysholm score of less than 64 points and ( 4 ) gmed 
 weakness with lower than grade 4 ( good ) at manual muscle testing ( grade 0 to grade 4 ) 
 according to muscle strength grade standard by kendall et al11 .
mmt : manual muscle test the participants were randomly divided into group i ; vmo strengthening exercise through 
 squat with isometric hip adduction ( siha ) , group ii ; gmed strengthening exercise through hip 
 abduction in side - lying ( abd ) , and combined exercise group iii . for the intervention method of group i ,
the participant s knee joint flexion was set to 45 
 degrees using a goniometer .
for femur and 
 tibia to maintain neutral position , the patient was controlled to avoid hip joint adduction 
 keeping the center of patella in line with the second toe .
a pillow was placed in the middle 
 of both patella and the knees were flexed to 45 degrees ( squatting position ) and then the 
 participant came back to standing position12 .
on the basis of 10rm ( repetition maximum ) , ability to repeat the 
 squatting 10 times , the participant had 10-second break between the 20-minute exercise . for 
 the abd starting position of group ii ,
the hip and knees were fixed to be flexed to 45 
 degrees and 90 degrees retrospectively in a side lying position and the back and foot - floor 
 were fixed on the wall .
the participant abducted the hip to 40 degrees with the thera - band 
 looped around the knees and came back to the original position13 .
on the basis of 10rm ( repetition maximum ) , ability to 
 repeat the movement 10 times , the participant had 10-second break between the 20-minute 
 exercise .
group iii conducted siha for 10 minutes and abd for 10 minutes and had 10-second 
 break between the exercises .
all groups conducted the exercises with a load of 70% 1rm three 
 times a week for 5 weeks .
the scale items include limp , 
 support ( using stick or crutches ) , stair - climbing , squatting , instability ( walking , running , 
 and jumping ) , pain , swelling , and thigh atrophy to evaluate instability of knee joint . 

visual analog scale ( vas , gymna , belgium ) was used to evaluate the 
 pain level of knee joint numerically .
18.0 was used to analyze the data and the mean value and standard 
 deviation were calculated .
two - way repeated measures anova was used to investigate the 
 interaction effect between the group and period .
two - way repeated measures anova about the lysholm score revealed that there was a 
 significant interaction between the group and period ( p<0.05 ) ( table 2table 2.changes in the results of the lysholm score and vas ( unit : score)group i(siha)group ii(abd)group iii(siha+abd)lysholm score*pre - operation50.0  7.147.7  9.349.4  9.34 week41.2  5.538.8  5.138.1  4.78 week61.1  4.060.0  3.775.1  4.6vas*pre - operation6.8  0.86.6  1.06.4  1.14 week5.1  0.65.0  0.75.0  0.88 week4.0 
siha : squat with isometric hip adduction ; abd : hip abduction 
 in side - lying ; vas : visual analog scale .
significance was tested by two - way repeated 
 measures anova . * between - group
vas for knee joint pain evaluation showed that there was a significant 
 interaction between the group and period ( p<0.05 ) ( table 2 ) .
siha : squat with isometric hip adduction ; abd : hip abduction 
 in side - lying ; vas : visual analog scale .
significance was tested by two - way repeated 
 measures anova . * between - group
this study conducted siha and abd exercise and combined exercises of the two with the 
 patients who had meniscal surgery 4 weeks ago in terms of vmo strengthening and selective 
 strengthening of gmed and analyzed the lysholm score and vas .
squat is a closed kinetic chain exercise that uses various joints and muscles in one 
 action .
it is an effective and safe intervention method because co - contraction of 
 surrounding muscles of knee increases and tension on anterior cruciate ligament is 
 minimized14 . in the squat intervention
, 
 a pillow was placed between the knees to maintain neutral position and semi - squat to 45 
 degrees flexion was conducted to selectively strengthen vmo and induce isometric hip joint 
 adduction9 .
this result occurred because femur and tibia maintained 
 neutral position and siha exercise was performed with knee joints flexed to 45 degrees in 
 this study .
thus , vmo activity was strengthened rather than vl and iliotibial tract and 
 lateral knee vector quantity was controlled so that patella could move through normal 
 pathway .
nyland et al.12 showed that the 
 squat exercise with isometric hip joint adduction would increase gmed activity because it is 
 related to pelvic stability and controls femur internal rotation .
gmed weakness causes overactivity and shortness of tensor fasciae latae and iliotibial 
 tract and gonarthritis because of lack of lateral knee joint stability15 .
as siha exercise group , 
 abd group showed that the lysholm score increased and vas decreased .
the combined exercise 
 group ( siha with abd ) showed more improvement than siha and abd group : knee functional index 
 increased and pain decreased .
this result is consistent with a previous study in that hip 
 joint adduction and internal rotation due to failure of hip abductor and hip external 
 rotator to handle increased stress on knee joint caused excessive knee valgus due to 
 weakness and atrophy of vmo and this produced lateral movement of patella9 .
hip joint abduction exercise in a side lying position is commonly used open kinetic chain 
 exercises . a study about strengthening hip muscles by distefano et al . revealed that gmed 
 had the greatest muscle activity in a side lying position after 12 exercise programs16 .
therefore , clinical use of gmed 
 strengthening exercise with hip joint abduction in a side lying position should be conducted 
 carefully .
a limitation of this study was that surgical method the patient received before the test , 
 whether it was menisectomy or meniscus repair , was not specified .
in addition , whether the 
 patient had medial or lateral meniscal injury was also not specified . therefore , gmed strengthening for the patients with meniscal surgery improved knee joint 
 function recovery and pain in this study and systematic rehabilitation program should be 
 actively suggested to patients and conducted in early stage .
 [ purpose ] the purpose of this study was to analyze the effect of gluteus medius activity 
 strengthening due to squat with isometric hip adduction and hip abduction in side - lying 
 exercise on knee joint function index and pain in meniscal surgery patients . 
 [ subjects and 
 methods ] this study selected sample of 26 patients who had meniscal surgery more than 4 
 weeks ago . 
 the patients were divided into squat with isometric hip adduction exercise 
 group i ( n=8 ) , hip abduction in side - lying exercise group ii ( n=9 ) , and combined exercise 
 group iii . 
 the lysholm score was used to evaluate knee joint function and visual analog 
 scale was used to evaluate pain index of knee joint . [ results ] two - way repeated measures 
 anova was used to analyze the lysholm score and visual analog scale and showed significant 
 interaction between the groups and durations . 
 [ conclusion ] strengthening vastus medialis 
 oblique and gluteus medius improved functional recovery and pain reduction of knee joint 
 in meniscal injury surgery patients . 
 gluteus medius strengthening exercise is essential to 
 meniscal injury surgery patients and should be included in rehabilitation program in early 
 stages to be conducted systematically . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION