osteoarthritis ( oa ) of the knee is a common problem causing knee pain and physical 
 disabilities in the elderly1 .
the 
 prevalence of knee oa is known to increase with age not only in japan but also in various 
 countries , meaning it is an important social issue around the world2 , 3 .
recently , research 
 on osteoarthritis against disability ( road ) studies in japan revealed an association between 
 knee pain and joint space narrowing in men , while women tended to have knee pain even 
 without radiographic knee oa .
in general , a progression of radiographic change is thought to 
 be a crucial indicator for assessing the severity of knee oa4 , 5 . however , there is a 
 widespread belief of inconsistency between clinical symptoms and radiographic severity6 , 7 .
for instance , sun et al . 
 reported that the serum il-15 levels independently and positively correlated with pain 
 severity but not kl grades in oa patients and , therefore , joint inflammation might play a 
 key role , reflected by the severity of the symptoms8 .
the oa research society international ( oarsi ) guidelines for management of knee oa 
 established by several orthopedic associations in each country9 , recommend physical exercises as a core treatment method . indeed
, 
 some articles revealed that aerobic exercise and resistance training decreased serum levels 
 of inflammatory mediators10 . also , the multicenter osteoarthritis study recently reported a significant concordance 
 between knee pain and radiographic knee oa by kellgren and lawrence grades11 .
oa , there is little evidence indicating 
 the effectiveness of physical exercise in cases of severe radiographic knee oa .
therefore , in this study , we tried to investigate the efficacy of supervised physical 
 exercise for the symptoms in patients with knee oa by separating them into two groups : one 
 group consisting of patients conducting supervised physical exercise ; and the other treated 
 by conventional clinical methods . for our results , we used both the japanese knee 
 osteoarthritis measure ( jkom)12 and the 
 pain disability assessment scale ( pdas)13 .
the jkom has been established to assess the activity of daily life 
 as well as pain and stiffness deriving from patients with knee oa in japan .
furthermore , we 
 also evaluated the pain related disabilities in patients with severe knee oa using the pdas 
 because previous reports indicated that knee pain was subject to vary within months and 
 weeks irrespective of radiographic severity14 .
this prospective study was conducted longitudinally for one year to confirm the mid - term 
 efficacy of each treatment method .
the study received ethical approval from the research ethics committee of the aichi medical 
 university ( no.12 - 101 ) .
patients with knee pain , confirmed with radiographic knee oa with a face of grade 3 or 
 above according to the kellgren - lawrence ( k - l ) grading system were eligible for this study . 

eligibility criteria included patients older than 50  years and without total knee 
 arthroplasty in either knee .
we recruited participants who were interested in this study , 
 which investigated knee - related health conditions using a specific questionnaire .
we divided subjects into one of two different 
 groups based on their knee care .
we defined subjects in one group ( n=26 ) as doing exercise 
 for at least one year or more at a physical fitness center in aichi medical university 
 regardless of whether they were receiving other forms of treatment or not ( exercise group ) . 

we defined subjects in the other group ( n=40 ) as treated at an orthopedic clinic in aichi 
 medical university without using any physical fitness center ( clinical group ) .
accordingly , 
 what treatment subjects received was already decided , and , therefore , it was hard to change 
 the arm . as a result , this study was a non - randomized clinical trial . before investigating their status , each subject was fully informed by an investigator : 1 ) 
 on the content of this study and 2 ) that all personal information of the subject would be 
 kept confidential . after investigating their demographic backgrounds ( age , gender )
, subjects received a 
 radiographic examination of both knees by the posterior - anterior view at standing position 
 to confirm radiographic severity .
these radiographs were assessed by at least two orthopedic 
 physicians according to the k - l grading system that uses the following grades : 0 , normal ; 1 , 
 possible osteophytes only ; 2 , definite osteophytes and possible joint space narrowing ; 3 , 
 moderate osteophytes and/or definite joint space narrowing ; and 4 , large osteophytes , severe 
 joint space narrowing , and/or bony sclerosis6 .
substantially , each radiographic score was decided according to the 
 higher k - l grade of either side .
participants also filled out two types of questionnaires , the japanese knee osteoarthritis 
 measure ( jkom)12 and the pain disability 
 assessment scale ( pdas ) to assess their knee pain and pain - related disabilities13.the jkom consists of a pain rating based 
 on a 100-mm visual analog scale ( vas ) and scores for a subscale of four symptoms based on a 
 disease - specific questionnaire addressing four dimensions : 
pain / stiffness ,  condition in 
 daily life ,  general conditions and  health conditions , with 8 , 10 , 5 and 2 questions , 
 respectively12 .
questions are rated on 
 an ordinal scale of 04 , with higher scores indicating a symptom or medical condition of 
 higher severity .
the four symptom subscales can be scored separately or combined to 
 represent the aggregated total symptoms . on the other hand ,
the pdas is a scale for 
 measuring lifestyle disabilities of patients with chronic pain .
higher scores ( on a scale of 
 0 to 60 points ) indicate greater degrees of lifestyle disability13 .
after one - year follow - up , three patients in the exercise group and 17 patients in the 
 clinical group were excluded as they had dropped out of the study .
reasons for dropout were 
 different for each participant and included receiving total knee arthroplasty ( one subject ) , 
 seeking other treatments , and unknown reasons .
accordingly , we collected data for this 
 research study from 43 patients in total , of which 20 patients were from the exercise group 
 and 23 patients were from the clinical group voluntary - based supervised exercise consisted of a complex program such as land - based 
 aerobic activities15 ( e.g. cycling ) , 
 stretching16 , muscle strengthening 
 ( e.g. quadriceps and hamstrings strengthening)17 and aqua - based exercise ( e.g. water walking)18 in our fitness center .
we adjusted these exercise programs 
 for each individual under the supervision of a physical therapist .
for instance , subjects 
 were instructed on knee stretching based on our stretching technique that could stretch the 
 target muscle without decreasing muscle strength19 .
subjects used muscle strengthening exercises with some machines 
 for both quadriceps and hamstrings , however when the subject complained of knee pain during 
 the exercise , the magnitude of leg load was regulated according to the severity of the 
 symptoms to prevent an aggravation of symptoms or subjects were instructed to only isometric 
 quadriceps contraction20 . moreover ,
when 
 the subject had knee swelling , only water walking was advised as aerobic exercise by a 
 therapist without cycling or treadmill walking .
an exercise session was approximately 90 to 
 120 minutes divided by several breaks for each subject adjusted by endurance .
although the 
 frequency of exercise was different for each subject according to their convenience , 
 everyone exercised one to three times in a week but at least once a week in our fitness 
 center .
seven participants in the exercise group regularly received intra - articular 
 hyaluronic acid injections in other clinics once a month .
by contrast , conventional treatment in the clinic included nonsteroidal anti - inflammatory 
 drugs ( nsaids ) and intra - articular hyaluronic acid injections .
patient consultations were 
 usually conducted once or twice a month for each subject . at baseline , we compared demographic and morphological parameters among the groups , for age 
 using the mann - whitney u test and for gender and k - l grades using the  test . 

two - way repeated measures analysis of variance ( anova ) was performed to examine the effects 
 over time and by group on the jkom score and pdas score with a scheff post - hoc comparison . 

subsequently , four symptom subscales of jkom were evaluated to examine separate effects of 
 each treatment using the wilcoxon signed - rank test .
we preformed all analyses with spss 
 software ( version 20.0  j ; spss inc . ,
there was no significant difference in the epidemiological background ( age p=0.57 , gender 
 ratio p=0.54 ) and radiographic severity of knees among the two groups , although there was a 
 different trend in the severity of k - l grade ( p=0.07 ) ( table 1table 1.patients demographic backgroundexercise groupclinical groupage ( years)72.06.173.96.9male / female5 / 154 / 19grade 3 / grade 415 / 511 / 12ages are reported as meansd . each category was compared among the groups , for age using the mann - whitney u test 
 and for gender and k - l grades using  test .
both analyses showed no 
 significant difference among the groups ( p>0.05 ) . ) .
each category was compared among the groups , for age using the mann - whitney u test 
 and for gender and k - l grades using  test .
two - way repeated measures anova did not show a significant time - course effect ( f=0.04 
 p=0.83 ) or interaction ( f=3.40 p=0.07 ) between time - course and group in jkom score . 

similarly , it did not show any significant time - course ( f=0.27 p=0.61 ) or interaction 
 ( f=0.17 p=0.69 ) between time - course and group in the pdas score .
however , there were 
 significant group effects in both the jkom score ( f=6.98 p=0.01 ) and pdas score ( f=5.49 
 p=0.02 ) .
post hoc analysis revealed that only the patients in the exercise group showed significant 
 improvement in their jkom score at one year after baseline ( p<0.05 , scheff comparison ) . 

moreover , they revealed a significant difference in pdas score among the groups at baseline 
 ( p<0.05 ) , although there is no significant difference in jkom score ( table 2table 2.jkom score and pdas score at baseline and one - year later in each groupbaselineone - year laterjkomexercise group20.816.017.314.4 * clinical group27.015.529.815.1pdasexercise group11.49.4 9.111.4 * clinical group16.410.816.310.4data are reported as meansd .  
p<0.05 , baseline vs. one - year later ; p<0.05 , 
 p<0.01 exercise vs. clinical ( post hoc scheff comparison ) .
jkom : japanese knee osteoarthritis measure , pdas : pain disability assessment 
 scale ) . on the other hand , in the jkom subscale
, the scores related to general 
 conditions and health conditions in the exercise group had significantly improved at one 
 year after baseline ( p<0.01 , wilcoxon signed - rank test ) .
in contrast , the score related 
 to pain / stiffness in the clinical group had significantly declined one year after baseline 
 ( p<0.05 , wilcoxon signed - rank test ) ( table 
 3table 3.outcome on subscales of jkom score in each groupexercise groupclinical groupbaselineone - year laterbaselineone - year laterpain / stiffness8.36.26.24.99.65.611.55.8 * condition in daily life6.25.34.25.39.76.710.46.7general conditions3.34.51.12.8 * * 4.94.64.74.0health conditions3.01.61.91.3 * * 2.91.43.11.2data are reported as meansd .
* p<0.05 , * * p<0.01 , baseline vs. one - year later ( wilcoxon signed - rank test ) .
p<0.05 , baseline vs. one - year later ; p<0.05 , 
 p<0.01 exercise vs. clinical ( post hoc scheff comparison ) .
jkom : japanese knee osteoarthritis measure , pdas : pain disability assessment 
 scale data are reported as meansd .
* p<0.05 , * * p<0.01 , baseline vs. one - year later ( wilcoxon signed - rank test ) .
what is novel about this study is how we revealed that patients with knee oa conducting 
 supervised exercise have the potential to maintain better clinical outcomes at one - year 
 follow - up , despite severe morphological degeneration in their knees .
. however , evidence on the efficacy of physical exercise for severe knee oa is 
 limited to short - term studies as previous studies were short - term ; usually conducted as a 
 patient waited for total knee joint replacement21 .
the consensus on the non - surgical management of knee oa includes stepwise treatment options 
 such as voluntary - based physical exercise , education for weight control , physiotherapy , 
 analgesic drugs such as nsaids and acetaminophen , and intra - articular injection of steroids 
 and hyaluronic acids22 . in cases where 
 this fails
on 
 the other hand , the present study showed that there was a significant difference between the 
 exercise group and the clinical group regarding the clinical outcomes at one - year follow - up 
 with an advantage in the exercise group .
this result indicates that treatment methods for 
 severe knee oa may be an important factor preventing knee arthroplasty in the future , 
 although several studies have indicated that the proportion of knees with a kl grade of 3 or 
 4 exceeded 95% in patients scheduled for knee joint replacement23 , 24 .
our study also documented that supervised physical exercise particularly improved general 
 conditions and health conditions but not the pain / stiffness condition in the jkom score .
we 
 believe that the former finding offers useful insight into patients with severe radiographic 
 knee oa to prolong the life of native knees regardless of pain and functional decline , 
 although these effects might derive from not only an exercise but also a self - care 
 motivation .
however , the latter result and decline in the pain - subscale in the clinical 
 group may be associated with previous descriptions7 , 
 11 . moreover , although our exercise 
 program included land - based aerobic activities , muscle strength , and aqua - based exercises , 
 based on much evidence in the literature9 , 
 we found that it had limited efficacy on pain in knees suffering from severe degeneration . 

this may indicate that chronic morphological degeneration may have the effect of decreasing 
 the regenerative capacity in local tissues24 .
in particular , the motivational component for one s health such as the 
 ability of self - efficacy was not excluded , although self - efficacy is an important factor for 
 keeping in sound condition even if people have chronic pain . in our study , the participants 
 in the exercise group were probably highly motivated to take care of themselves . in 
 contrast , although the subjects in the clinical group were instructed to follow voluntary 
 home exercises in accordance with their physician s guidelines , we speculate that most did 
 not carry them out with a passive treatable attitude
. we could not determine the causes of 
 participant dropout , but we speculate that a difference in the dropout rate between the 
 exercise group ( 13% ) and the clinical group ( 46% ) derived from the difference in their 
 self - care motivation . certainly , there was a significant difference in pdas scores among the 
 groups at the beginning of this study .
hence , we think that the motivational component has 
 influenced the results of this study . secondly , we saw many patients in the clinical group 
 drop out of the study .
as several studies have reported elsewhere , evidence on the 
 effectiveness of non - pharmacological and non - surgical approaches for severe knee oa are 
 limited to the short - term .
we think this is 
 because knee arthroplasty can lead to an early solution to knee problems9 .
therefore long - term studies in severe knee 
 oa are difficult . excluding cases in which the patient wants to keep their native knees and 

self - care motivation bias will exist as long as we examine the long - term effects of physical 
 exercise for severe knee
oa . moreover , most of the patients with severe knee oa are elderly 
 people , and they usually have many disorders , not only in the knee .
hence , general problems 
 among elderly patients might be the reason they drop out of longitudinal studies .
thirdly , 
 although there was no statistical difference between the exercise group and the clinical 
 group regarding their radiological severities , the rate of mild degeneration ( grade 
 3>grade 4 ) was higher in the exercise group than in the clinical group .
comparative 
 analysis between the groups at baseline showed that this might affect the main results of 
 this study .
therefore , we believe further studies need to be conducted to confirm the effect 
 of supervised exercise on severe knee oa by investigating both the survival rate of native 
 knees and the life expectancy in such patients .
 [ purpose ] in this study , we investigated the efficacy of supervised physical exercise or 
 conventional treatment on symptomatic knee osteoarthritis with severe morphological 
 degeneration . 
 [ subjects ] sixty - six patients with severe radiographic knee osteoarthritis 
 were enrolled . 
 [ methods ] participants were separated into two groups : in one group 
 patients conducted physical exercise under supervision ; while in the other group they were 
 treated by conventional clinical methods for one year . 
 participants filled out two types 
 of questionnaires ; the japanese knee osteoarthritis measure and the pain disability 
 assessment scale at baseline and one year following enrollment in the study . 
 two - way 
 repeated measures analysis of variance was used to examine the effects over time and by 
 group for a total of 43 participants ; consisting of an exercise group ( n=20 ) and a 
 clinical group ( n=23 ) excluding 23 dropouts . 
 [ results ] analysis did not show a significant 
 time - course effect or interaction between time - course and the groups in both 
 questionnaires . on the other hand 
 , there were significant group effects in both 
 questionnaires with an advantage in the exercise group . 
 [ conclusion ] these results 
 indicate that patients with knee osteoarthritis under supervised exercise conditions are 
 more likely to maintain a better clinical outcome at one - year follow - up , despite the 
 severe morphological degeneration in their knees . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION