postural anomalies are widespread and are exhibited by people of all demographics . while 
 commonly attributed to lack of physical activity , poor posture is especially prominent in 
 individuals who spend long periods of time sitting at a desk or computer , as is necessary 
 with many jobs in developed countries1,2,3 . 

poor posture is a major causative factor of many musculoskeletal problems , including joint 
 stress , pain , and various diseases4,5,6,7,8,9,10,11 .
detecting irregularities in posture is an 
 important component in understanding sources of pain and limited movement , and for 
 subsequently developing mitigation strategies such as corrective exercises . due to its 
 dynamic nature ,
objective analysis often utilizes 
 elaborate technology , such as x - ray imaging and 3d motion capture , which provide a valid and 
 reliable assessment ; however , these capabilities are found only in specialized clinics12 . in an effort to address this limitation , 

portable device technology has been developed hand - in - hand with medical technology to 
 provide non - invasive , user - friendly , and affordable posture - assessing software designed for 
 use by physical therapists , chiropractors , and other health and fitness professionals . 

, trinity , fl , usa ) is a novel , commercially 
 sold photographic mobile application that enables the identification of deviations from the 
 ideal standing posture .
the posturescreen mobile ( psm ) application facilitates 
 the assessment of posture in a variety of settings .
while the convenience of this tool is 
 evident , the information provided would only be useful if the measurements were repeatable 
 between multiple visits and reproducible between multiple examiners .
therefore , the purpose 
 of this study was to investigate the inter- and intra - rater agreement when using psm , as 
 well as understanding whether standard clothing can obscure the reliability of such 
 measurements .
one experienced licensed physical therapist ( a doctor of physical therapy ) and two 
 inexperienced examiners ( undergraduate students ) performed repeated postural assessments of 
 10 subjects wearing both full and minimal clothing on two nonconsecutive days using psm 
 installed on a tablet ( ipad ; apple inc . ,
cupertino , ca , usa ) . an initial set of posture 
 images was captured with subjects dressed in standard street clothing .
a second set of 
 images was captured on the same visit with subjects wearing minimal clothing ( shorts for 
 men , and shorts and a sports bra for women ) .
a third set of images was captured 48 hours 
 later in the minimally clothed condition .
subjects were recruited randomly from the ucla community , based on 
 availability , not on postural qualifications .
this study was approved by the ucla 
 institutional review board and all participants gave their written informed consent . 

participants completed standard health , medical , and exercise history forms following 
 enrollment and prior to data acquisition . before each assessment
, the room was set up in a 
 standardized way to ensure uniform conditions throughout the test .
tape was placed on the 
 floor to indicate where the subject should stand for the anterior picture .
a second piece of 
 tape was laid perpendicular to the first piece to indicate the positioning for the lateral 
 picture .
the tablet was placed on a stand exactly 10 feet away from the subject markers at a 
 height of 4.5 feet to standardize the image angle .
height was measured to the nearest 0.5  cm using a wall - mounted 
 stadiometer , and weight was measured to the nearest 0.1  kg with an octopolar bioelectrical 
 impedance scale ( biospace inbody r20 ; inbody co. ltd . ,
subjects were 
 instructed to stand at the tape marks in a comfortable position with weight evenly 
 distributed on both legs and to look at a marker placed on the wall in front of them at eye 
 level . to help eliminate potential deviations from their routine posture ,
subjects were 
 asked to stand on their right foot for a few seconds and then shift their balance to the 
 left foot for a few seconds .
subjects then placed both feet on the ground and an image was 
 captured using psm and the camera function of the ipad .
this process was repeated to obtain 
 both an anterior and right lateral view of each subject .
an initial set of images was captured with subjects 
 dressed in standard street clothing with their shoes removed .
a second set of images was 
 captured on the same visit with subjects wearing minimal clothing ( shorts for men , and 
 shorts and a sports bra for women ) also with their shoes removed .
an identical third 
 examination was conducted 48 hours later in the minimally clothed condition .
subjects were 
 asked to refrain from strenuous physical activity between visits in order to reduce external 
 factors influencing postural variation .
three examiners analyzed each set of data by 
 following the psm prompts to select 17 specific anatomical landmarks .
twelve landmarks were 
 placed on the anterior view image at the following locations : the right pupil , left pupil , 
 midpoint between the nose and upper lip , top of the right acromioclavicular ( ac ) joint , 
 episternal notch , top of the left ac joint , right lateral rib t8 level , left lateral rib t8 
 level , right anterior superior iliac spine ( asis ) , left asis , center of the right talus , and 
 center of the left talus .
five landmarks were placed on the lateral view image at the 
 following locations : the external auditory meatus , center of the shoulder at the 
 cervicothoracic junction , greater trochanter , center of the tibiofemoral joint , and center 
 of the malleolus .
psm then calculated the following 13 quantitative data points using 
 proprietary algorithms : head shift ( lateral ) , head shift ( longitudinal ) , head tilt , 
 shoulder shift ( lateral ) , shoulder shift ( longitudinal ) , shoulder tilt , ribcage shift , hip 
 shift ( lateral ) , hip shift ( longitudinal ) , hip tilt , head weight , effective head 
 weight , defined as how heavy the head feels to its supporting structures based on 
 any postural deviations , and knee shift .
intraclass correlation 
 coefficients ( iccs ) were derived by calculating between - subject variance as a fraction of 
 the total variance of each of the 13 postural measurements made by all three examiners to 
 determine inter - rater agreement .
inter - rater agreement was calculated separately for the 
 fully clothed and minimally clothed conditions .
additionally , iccs were calculated for the 
 measurements of the two minimally clothed examinations conducted by the experienced examiner 
 on separate occasions to determine the intra - rater agreement of the measurements .
iccs 
 greater than 0.60 but less than or equal to 0.80 ( 0.60<icc0.80 ) were considered to 
 indicate  substantial  agreement , while iccs equal to or greater than 0.81 ( icc0.81 ) were 
 considered to indicate 
the postural measures of head weight and 
 effective head weight were omitted from the analysis because these were 
 considered to be affected more by body weight than by the placement of landmarks by the 
 raters .
ten subjects ( five females ) completed the study ( age 21  1  years ; height 172  11  cm ; 
 weight 70  14  kg ; mean  sd ) .
inter - rater agreement for both the fully and minimally 
 clothed conditions and the intra - rater agreement for the minimally clothed condition are 
 reported in table 1table 1.levels of agreement of repeated measurementsposturalmeasurementsintraclass correlation coefficientsfully clothed(3 examiners)minimally clothed(3 examiners)minimally clothed(2 visits)head shift lateral0.87 * 0.83 * 0.46head shift ap0.550.720.73head tilt0.91 * 0.86 * 0.78shoulder shift lateral0.670.640.33shoulder shift ap0.750.720.68shoulder tilt0.580.88 * 0.78hip shift lateral0.95 * 0.93 * 0.76hip shift ap0.640.550.84*hip tilt0.100.260.59head weight1.001.000.90effective head weight0.980.960.84rib cage shift0.190.580.59knee shift0.88 * 0.750.86*data are intraclass correlation coefficients ( iccs ) where 
 0.40<icc0.60 indicate moderate agreement , 0.60<icc0.80 indicate substantial 
 agreement and icc0.81 indicate almost perfect agreement .
head weight 
 and effective head weight were omitted from the analysis because they 
 were considered to be affected more by body weight than by the placement of landmarks 
 by the raters .
inter - rater agreement of the fully clothed exam was at least substantial 
 ( icc>0.60 ) for seven measures and specifically almost perfect ( icc0.81 ) for : 
 head shift lateral , head tilt , hip shift lateral , and 
 knee shift .
inter - rater agreement of the minimally clothed exam was 
 almost perfect for the previously identified measures minus knee shift but 
 plus shoulder tilt . in the minimally clothed condition , only hip 
 tilt failed to reach at least moderate agreement ( 0.40<icc0.60 ) .
intra - rater 
 agreement ( between visits ) for the minimally clothed exams was at least substantial 
 ( icc>0.60 ) for seven measures and specifically almost perfect for : hip shift 
 anterior / posterior ( hip shift ap ) and knee shift .
there were 
 large differences between inter- and intra - rater agreement for head shift 
 lateral ( 0.826 vs. 0.457 ) and shoulder shift lateral ( 0.642 vs. 
 0.332 ) , with both failing to have substantial intra - rater agreement despite having met or 
 exceeded this level of agreement in the inter - rater analysis .
in contrast , hip 
 tilt possessed a low inter - rater agreement ( icc=0.256 ) but registered a much 
 higher intra - rater agreement ( icc=0.588 ) .
data are intraclass correlation coefficients ( iccs ) where 
 0.40<icc0.60 indicate moderate agreement , 0.60<icc0.80 indicate substantial 
 agreement and icc0.81 indicate almost perfect agreement .
head weight 
 and effective head weight were omitted from the analysis because they 
 were considered to be affected more by body weight than by the placement of landmarks 
 by the raters .
to the best of our knowledge , this is the first published study that has examined both the 
 inter- and intra - rater agreement of the mobile application , posturescreen 
 mobile , for screening static posture .
acceptable levels of agreement were found 
 among the measurements of three different examiners of varying experience .
overall 
 inter - rater agreement was substantial whether the examination was conducted on a fully 
 clothed or minimally clothed subject , with 7 of the 11 measures exceeding an icc of 0.60 in 
 the fully clothed condition . in the fully clothed condition , the examiners evaluation of 
 head position in the frontal plane ( head shift lateral , head tilt ) , weight 
 shift in the frontal plane ( hip shift lateral ) , and one of three measures 
 relating to weight shift in the sagittal plane ( knee shift ) using psm were 
 especially reproducible ( icc0.81 ) .
unsurprisingly , removing the shirt ( i.e. , creating a 
 minimally clothed condition ) improved the agreement of measures relying on upper body 
 landmarks on the acromioclavicular joints and rib cage .
for example , the rib cage 
 shift measure improved from slight agreement ( 0.01<icc0.20 ) to moderate 
 agreement .
importantly , the head shift anterior / posterior ( head shift ap ) 
 measure showed substantial agreement ( icc=0.724 ) in the minimally clothed condition . 
 head shift ap may be the most clinically relevant measure provided by psm 
 as it enables a quantitative diagnosis of forward head posture .
forward head posture is a 
 common postural deviation in developed countries and it is believed to be a causative factor 
 of many musculoskeletal diseases , including migraine and chronic tension headaches10 , 11 .
traditional means of diagnosing this postural condition involve 
 manually determining the angle between the horizontal and a line running from the c7 
 vertebra to the tragus of the ear from a sagittal photograph14 .
a quick , yet reliable , means of determining this angle could 
 greatly simplify management of cervical - spine - related disorders .
posture measures that 
 failed to reach substantial agreement in the minimally clothed condition tended to rely on 
 anatomical landmarks that are either difficult to observe ( e.g. , anterior superior iliac 
 spine , greater trochanter ) or non - specific ( e.g. , rib cage ) .
hip tilt stood 
 out as having notably poor inter - rater agreement . even among highly experienced examiners , 

identification of pelvic deviation via hands - on palpation can prove challenging and 
 inexact15,16,17 .
therefore , it is 
 unsurprising that attempts to identify this phenomenon via photographic observation were 
 less reliable .
however , the strong intra - rater agreement of hip tilt could 
 indicate that this measure , unlike the other 10 , requires an experienced examiner , meaning 
 the undergraduate examiners were not able to reliably estimate the location of the 
 landmarks .
however , since we did not assess intra - rater agreement for the inexperienced 
 examiners , this can not be stated conclusively .
alternatively , it is possible that each 
 examiner has their own consistent , even if inaccurate , idea of where the asis is located 
 when analyzing the photographs .
in addition to evaluating the performance of the examiner , 
 intra - rater agreement could be considered a partial measure of postural consistency within 
 participants , at least among measures with strong inter - rater agreement . between - visit 
 variations
suggest certain aspects of posture may be highly inconsistent within individuals 
 on a day - to - day basis .
all lower body weight shift measures ( hip shift ap , hip shift 
 lateral , and knee shift ) appear to have remained fairly 
 consistent across visits , possibly because we asked subjects to unweight each foot prior to 
 each exam , thus standardizing the lower extremity weight shift preference for each visit . in 
 contrast , none of the weight shift measures above the waist reached almost perfect 
 agreement , indicating the variable nature of weight shift preference from moment - to - moment 
 even with a stable lower body .
a previous study by hopkins18 , tested the validity and intra - rater agreement of psm by comparing 
 it with the vicon 3d motion analysis system ( vicon motion systems , oxford , united kingdom ) 
 as the gold - standard measure19 .
this 
 investigator found that the shift and tilt measurements using psm were repeatedly higher 
 than those measured by the vicon system in the frontal view . in the lateral view , the 
 results reversed 
these significant 
 differences in variation persisted with and without the use of anatomical markers .
unlike 
 this study , hopkins found that the trial - to - trial variance with psm exhibited low 
 intra - rater agreement .
one such 
 posture assessment tool with 29 measurements was found to be highly reliable in a study by 
 ferreira et al.20 , with just 14.0% of 
 measurements for inter - rater agreement and 19.3% for intra - rater agreement failing to reach 
 an icc of at least 0.70 . while these findings were better than those of our present study of 
 psm ( with 30.7% of inter - rater and 38.5% of intra - rater measures with iccs lower than 
 0.700 ) , there is a trade - off between ease - of - use and time spent performing analysis .
the 
 study of ferreira et al.20 involved five 
 fully trained physical therapists and the software required identification of 32 anatomic 
 points .
it is noteworthy that psm performed reliably while requiring identification of only 
 17 points and when employed by inexperienced examiners .
one important finding of this study 
 is the inconsistency of posture between subject visits .
there are several factors that may 
 influence day - to - day posture including energy level , recent exertion , and involuntary 
 compensation to alleviate temporary discomfort . in order to minimize these confounding 
 factors ,
subjects were instructed not to perform any heavy lifting between visits . 
 nevertheless , any of these factors may have led to lower iccs that underestimate the true 
 inter - rater agreement .
future studies should build on the work of raine et al.14 to identify acceptable ranges for each 
 postural measure to allow categorization ( e.g. , normal , at risk , abnormal ) , which would 
 likely improve the clinical utility of this device .
psm appears to be a reliable and 
 user - friendly tool for characterizing static standing posture . to maximize agreement , 

assessments should be conducted with the subject wearing minimal clothing so as to better 
 identify anatomical landmarks .
our results indicate that usage of psm requires minimal 
 formal training since two inexperienced examiners reliably matched the trained physical 
 therapist in the determination of most measures .
moreover , psm may provide a cheaper , more 
 feasible alternative to more advanced methods for initial patient screenings or for 
 situations that do not require high precision . for assessments where a very high degree of 
 accuracy is required ,
this study did not receive any funding , and authors have no conflicts of interest to 
 declare .
this study did not receive any funding , and authors have no conflicts of interest to 
 declare .
 [ purpose ] to determine the intra- and inter - rater agreement of a mobile application , 
 posturescreen mobile ( psm ) , that assesses static standing posture . 
 [ subjects 
 and methods ] three examiners with different levels of experience of assessing posture , one 
 licensed physical therapist and two untrained undergraduate students , performed repeated 
 postural assessments of 10 subjects , fully clothed or minimally clothed , using psm on two 
 nonconsecutive days . 
 anterior and right lateral images were captured and seventeen 
 landmarks were identified on them . 
 intraclass correlation coefficients ( iccs ) were 
 calculated for each of 13 postural measures to evaluate inter - rater agreement on the first 
 visit ( fully or minimally clothed ) , as well as intra - rater agreement between the first and 
 second visits ( minimally clothed ) . [ results ] eleven postural measures 
 were ultimately 
 analyzed for inter- and intra - rater agreement . 
 inter - rater agreement was almost perfect 
 ( icc0.81 ) for four measures and substantial ( 0.60<icc0.80 ) for three measures during 
 the fully clothed exam . during the minimally clothed exam , 
 inter - rater agreement was 
 almost perfect for four measures and substantial for four measures . 
 intra - rater agreement 
 between two minimally clothed exams was almost perfect for two measures and substantial 
 for five measures . 
 [ conclusion ] psm is a widely available , inexpensive postural screening 
 tool that requires little formal training . to maximize inter- and intra - rater agreement , 
 postural screening using this mobile application should be conducted with subjects wearing 
 minimal clothing . assessing static standing posture via psm 
 gives repeatable measures for 
 anatomical landmarks that were found to have substantial or almost perfect agreement . 
 our 
 data also suggest that this technology may also be useful for diagnosing forward head 
 posture . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION
Conflicts of interest