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Paper text:
glenohumeral ( gh ) joint contracture can occur after repair of rotator cuff tears , frozen 
 shoulder , and rheumatoid arthritis1 .
this 
 can be caused by capsular contracture , tendon shortening , and scars2 , 3 .
manual shoulder 
 joint test is the  end feel  that the physical therapist feels during the resistance of the 
 tissue against the force applied manually from the different directions of the articular 
 surface and greatly depends on subjective evaluation4 . to test the stiffness and looseness of the articular capsule , one 
 of the causes of limited shoulder movement , various orthopedic manual techniques are 
 used5 , 6 . according a study on manual therapy
, traction can be used as a diagnostic tool to assess 
 joint play or as treatment to relieve pain or improve joint mobility7 . in particular , the traction method according to the 
 kaltenborn - evjenth concept is a safe and effective method to test the condition of the 
 articular capsule in the field of orthopedic physical therapy8 .
g1 represents the 
 force necessary to remove the compressive forces acting on the joint . in grade 2 ( g2 ) , the 
 slack is taken up from the tissue surrounding the joint , which are then tightened . finally , 
 in grade 3 ( g3 ) , additional force is applied and the soft tissues surrounding the joint are 
 stretched ; thereby , separation of the joint surfaces is achieved .
traction is preferably performed in the maximal loose - packed position ( mlpp ) of the joint 
 ( shoulder 55 abduction and 30 horizontal adduction in the transverse plane ) . in the mlpp
, 
 the traction is generally assumed to be most effective because the joint capsule is most 
 relaxed10 .
dvorak and coworkers stated 
 that up to 5  mm of separation of the joint surfaces is physiological during joint play 
 testing11 .
gokeler et al . reported that in the comparison of joint space width ( jsw ) between the 
 humeral head and the glenoid fossa after applying a 14-kg load to the gh joint of the 
 asymptomatic subjects during manual traction , jsw was widened by about 0.3  mm , but 
 difference was not significant12 . 

meanwhile , in the research by sato et al . , jsws were compared after applying traction to the 
 point that the maximum resistance in the hip joint was detected in symptomatic subjects13 .
the results of the research indicated 
 that jsw was widened by about 0.9  mm , with a significant difference .
perhaps , the structural 
 difference between the gh and the hip joints in both research studies might have affected 
 the results .
therefore , when applying traction to the gh point , the exact degree of 
 separation of the humeral head from the glenoid fossa is unknown .
in addition , quantitative 
 reports related to the application of traction are lacking , and traction remains dependent 
 on the sensation felt by therapists in their fingertips .
the aim of this study was to 
 analyze the jsw of the humeral head and glenoid fossa during traction under 2 grade 
 conditions ( g2 and g3 ) .
the subjects of this study were individuals who did not have medical histories of shoulder 
 injury and damage to the nervous and musculoskeletal systems , which may affect the range of 
 shoulder movement , and have not performed shoulder muscle strength training during the 
 recent 6 months prior to the study .
the research subjects were selected from among 20 male 
 employees who worked at h hospital , located in ulsan metropolitan city . before starting the 
 test , they were given enough explanation on the test and participated voluntarily in the 
 test after submitting a signed consent form .
this study was approved by the ethics 
 commission of daegu university according to the declaration of helsinki .
the general 
 characteristics of the subject are shown in table 
 1table 1.general characteristics of subjects ( n = 20)characteristicsmean  sdage ( years)31.72.9height ( cm)174.63.7weight ( kg)70.57.0bmi ( kg / m)23.12.0bmi : body mass index . traction was applied to the dominant side of the subjects shoulder .
the dominant hand , 
 defined as the hand used for eating and writing , was the right hand in all of the subjects . 

the subjects lied down on the radiography table , rotating the trunk 30 to the right so that 
 the scapula at the shooting side touched on the table .
the opposite shoulder was supported 
 by using a triangular support angled at 30 so that the subject could lie down comfortably 
 while maintaining the rotated position . to prevent scapular movement during traction ,
the 
 tester positioned the subject s shoulder abduction to 50 after the subject s palms were 
 positioned facing up .
this position was used as the resting position and the mlpp of the 
 shoulder joint .
taking 
 the proximal humerus with both hands , the humerus was pulled toward the perpendicular 
 direction against the glenoid fossa .
the traction was performed by a physical therapist who 
 completed educational courses on the keltenborn - evejenth concept and had at least 10  years 
 of experience with joint mobilization . immediately after applying traction
all the radiographies were performed by 
 the same radiologist , with anteroposterior projection ( diagnostic radiography , listem , co. , 
 ltd . , japan ) .
for random assignment of order by grade , the subjects were told to pick one 
 card after placing cards with nos . 2 or 3 written on it in a box .
radiography was performed by applying the resting position , g3 on the first day , and g2 
 on the next day . for those who picked no .
2 , radiography was performed by applying the 
 resting position , g2 on the first day , and g3 on the next day .
radiography 
 was performed at the same hour for the same person for 2 days .
other grades were applied in 
 the same manner after 1 day so that the structure of the joint can return to its normal 
 condition . in the computer that received the images taken by using the pacs program ,
data were 
 calculated by using the method suggested by petersson and redlund - johnell14 . in this position ,
the projection of the 
 joint surface of the humeral head forms a semicircle , the diameter of which is the line 
 joining the two terminal points of the joint surface projection .
one point was determined 
 each at the superior and inferior edges of the glenoid fossa , making a total of three 
 points .
each of the three points of the glenoid cavity was connected to the center point of 
 the humeral head by placing the ruler .
the radiologist was told how to conduct the measurement before the test and made 
 to practice adequately how to measure by using the shoulder joint pictures obtained by other 
 radiologists .
in addition , information on the traction grade was withheld until all the 
 measurements were finished .
prior to the analysis , data normality were 
 tested by using the kolmogorov - smirnov .
icc(3.1 ) ( icc , intraclass correlation 
 coefficients ) was used to derive the intra - rater reliability of the jsw measurements .
to 
 compare jsw according to gh traction grade , one - way repeated - measures analysis of variance 
 ( anova ) was performed , and a least square difference was performed for post hoc analysis . 

the results of the statistical analyses are shown in table 2table 2.joint space width by the shoulder traction grade ( mean  sd)grouprestinggrade 2grade 3jsw ( mm)4.00.34.50.44.70.5significant difference between resting and grade 2 traction ( p < 
 0.05 ) . significant difference between resting and grade 3 traction ( p < 0.05 ) 
 jsw : joint space width .
the results of the one - way repeated - measures anova to verify the changes in 
 jsw according to grade indicated significant differences in jsw .
post hoc analysis showed 
 that the jsw was significantly higher with g3 traction than with g2 traction and resting 
 position .
however , no significant difference in jsw was found between g2 and g3 . the 
 intra - rater reliability for jsw measurements was good to excellent ( icc3,1 = 
 0.880.98 ) significant difference between resting and grade 2 traction ( p < 
 0.05 ) .
significant difference between resting and grade 3 traction ( p < 0.05 ) 
 jsw : joint space width
this study was performed to analyze the changes in jsw between the glenoid fossa and 
 humeral head , while gh traction was applied according to grade .
the jsw for the resting 
 position was 4  mm . in the kaltenborn - evjenth concept ,
g1 traction is explained as the stage 
 to remove the pressure force to the joint without separation of joint10 .
therefore , in this study , g1 traction was not applied in 
 the resting position . in the g2 traction ,
jsw was 4.5  mm , increased significantly by 0.5  mm from that in the 
 resting position .
g2 traction refers to the moment that the slack of the articular capsule 
 is released , and the collagen fibers within the tissue become tight by increasing the 
 tension gradually .
in addition , the jsw in the g3 traction was 4.7  mm , increased significantly by 0.7  mm from 
 that in the resting position . in the g3 traction ,
greater force than the traction given in 
 g2 was applied to the tissue , stretching the collagen fiber . in this moment , it does not 
 cross the rupture point of the collagen fiber , which explains the reason why jsw in the g3 
 traction was increased by 0.2  mm , more than the 0.5  mm in the g2 traction .
al . 
 reported that jsw was increased significantly by 0.9  mm , from 3.86 to 3.95  mm , as a result 
 of hip joint traction in the maximum relaxation position in the healthy adults13 .
applied a 14-kg 
 force , which is equivalent to the gh traction , to a healthy person for repair of the 
 scapula , and the jsw was increased by approximately 0.3  mm12 .
the difference is due to the position of the subject during 
 traction . in this study
, traction was performed in the supine position ; whereas in the 
 research by goker et al . , it was performed in the sitting position . considering that in the 
 sitting point , the humerus is affected by gravity
, the resistance of the tissue might be 
 increased while in the sitting position . as the resistance of the tissue was small because 
 most of the connective tissues are not affected by the gravity
dvorak and coworkers stated that up to 5  mm of separation is normal in the mlpp during 
 joint play testing but did not provide evidence to support their statement11 .
when g3 traction was applied , only an increase of 0.6  mm was 
 observed .
jsw was increased by 0.2  mm in g2 and g3 , but without significant difference .
this 
 means that jsw was not increased greatly even when greater force was applied through the g3 
 traction to the joint capsule stretched tightly in the g2 traction .
however , the therapists 
 can adequately feel the difference in the end feel of the tissue during the g3 traction .
the limitations of this study are as follows : first , as the number of the subjects was 
 small , the study results are hard to generalize .
second , as this study was performed with 
 healthy persons , we could not apply traction to the shoulder joint of patients with a frozen 
 shoulder .
many physical therapists have used traction according to the kaltenborn - evjenth concept , 
 but because they judge the grade subjectively , simply depending on the sensation of the 
 therapist and the end feel of the joint , they could not know exactly how much space within 
 the joint is separated , until recently . in conclusion , in this study , we found that although 
 the g2 and g3 tractions during the gh traction in the healthy persons did not significantly 
 differ , the increase in the jsw between the glenoid fossa and the humeral head was highest 
 during the g3 traction .
this is deemed to provide help for therapists in the safe and 
 effective application of traction techniques in clinical cases .
[ purpose ] the aim of this study was to analyze the joint space width of the humeral head 
 and glenoid fossa during traction under 2 grade conditions ( grade 2/grade 3 ) . [ subjects 
 and methods ] the subjects were 20 healthy male adults who had not experienced any shoulder 
 injury . 
 three radiographs were obtained with the subjects in the supine position ( resting , 
 grades 2 and 3 ) . 
 the glenohumeral joint space was examined on radiography . 
 joint space 
 width was measured by a radiologist at the points described by petersson and 
 redlund - johnell . a radiologist blinded to the variable  resting  or  
 traction  
 performed 
 all radiographic measurements . 
 the joint space widths were compared by using one - way 
 repeated - measures analysis of variance . 
 [ results ] the results of this study indicated 
 significant differences in the changes in joint space width according to traction grade . 
 compared to resting , grades 2 and 3 traction significantly increased joint space width . 
 
 however , no significant difference in joint space width was found between grades 2 and 3 
 traction . 
 [ conclusion ] although no significant differences were found 
 between grades 2 and 3 traction during glenohumeral joint traction , the increase in joint 
 space width between the glenoid fossa and humeral head was highest during grade 3 
 traction .