a cross - legged position is that in which the lower legs are folded towards the body , crossing each other at the ankle or calf , with both ankles on the floor .
this posture has various names originating from different cultural backgrounds : in english , it is referred to as indian style ; in many european languages , as turkish style ; and in korea , as yangban style .
sitting on the floor in a cross - legged position is common in the oriental culture but not in the western culture .
low back pain ( lbp ) associated with sitting on the chair has been widely studied .
some agree that prolonged static sitting and reduced lumbar lordosis are risk factors for lbp4,5,8,15 ) .
however , to the best of our knowledge , the effect of sitting on the floor on the sagittal lumbar curve has not been studied .
it is just presumed that sitting on the floor is worse for lbp than standing or sitting on a chair .
this study is designed for radiographic comparison of lumbar lordosis when standing , sitting on a chair , and sitting on the floor .
the aim of the present study is to determine the clinical significance of sitting on the floor on lumbar spinal alignment .
thirty asymptomatic volunteers among the hospital staff without a history of spinal pathology were recruited .
the study population comprised 11 women and 19 men with a mean age of 29.8 ( sd , 6.2 ) years ( range , 23 - 52 years ) .
lateral radiographs of the lumbar spine were obtained when standing , sitting on a chair , and sitting on the floor ( fig .
each person was asked to stand erect comfortably . the individual 's arms were flexed ; hands , placed on the clavicle ; and the knees , held in extension . for chair sitting ,
the height of the chair was adjusted to allow each participant 's hips and knees to flex approximately to 90 and for their feet to rest comfortably on the floor . for floor - sitting ,
each person was asked to sit crossed - legged on the floor in a comfortable position .
the distance from the radiographic source to the film was maintained at 230 cm for exposure .
an independent observer measured all radiographic assessments by using a measuring program with a built - in picture - archiving communication system ( piview ; infinitt co. ltd . ,
segmental lumbar lordosis ( sl ) between l1 to s1 and whole lumbar lordosis ( wl ) were assessed using the cobb 's angle in each position .
sl was defined as the cobb 's angle between the superior endplate line of the upper vertebra and the inferior endplate line of the lower vertebra .
sl at l5-s1 was defined as the cobb 's angle between the superior endplate line of l5 and the endplate line of s1 .
wl was defined as the cobb 's angle between the superior endplate line of l1 and the superior endplate line of s1 .
chicago , il , usa ) . a probability value of less than 0.05 was considered significant .
analysis of variance or the kruskal - wallis test was used for statistical analysis to compare the variables among the 3 groups .
if a significant difference was found , the bonferroni post hoc test was used to determine which groups were significantly different .
thirty asymptomatic volunteers among the hospital staff without a history of spinal pathology were recruited .
the study population comprised 11 women and 19 men with a mean age of 29.8 ( sd , 6.2 ) years ( range , 23 - 52 years ) .
lateral radiographs of the lumbar spine were obtained when standing , sitting on a chair , and sitting on the floor ( fig .
each person was asked to stand erect comfortably . the individual 's arms were flexed ; hands , placed on the clavicle ; and the knees , held in extension . for chair sitting ,
the height of the chair was adjusted to allow each participant 's hips and knees to flex approximately to 90 and for their feet to rest comfortably on the floor . for floor - sitting ,
each person was asked to sit crossed - legged on the floor in a comfortable position .
the distance from the radiographic source to the film was maintained at 230 cm for exposure .
an independent observer measured all radiographic assessments by using a measuring program with a built - in picture - archiving communication system ( piview ; infinitt co. ltd . ,
segmental lumbar lordosis ( sl ) between l1 to s1 and whole lumbar lordosis ( wl ) were assessed using the cobb 's angle in each position .
sl was defined as the cobb 's angle between the superior endplate line of the upper vertebra and the inferior endplate line of the lower vertebra .
sl at l5-s1 was defined as the cobb 's angle between the superior endplate line of l5 and the endplate line of s1 .
wl was defined as the cobb 's angle between the superior endplate line of l1 and the superior endplate line of s1 .
chicago , il , usa ) . a probability value of less than 0.05 was considered significant .
analysis of variance or the kruskal - wallis test was used for statistical analysis to compare the variables among the 3 groups .
if a significant difference was found , the bonferroni post hoc test was used to determine which groups were significantly different .
there were significant decreases in sl at all lumbar spine levels , except at the l1 - 2 level , when sitting on the floor as compared to when standing or sitting on a chair .
wl when sitting on the floor was decreased to -13.9 ( sd , 13.6 ) degrees from -50.0 ( sd , 9.2 ) degrees observed in the standing position ( 72.9% reduction ) .
table 3 shows the contribution of sl change to wl change during a change in the position . l5-s1 and l4 - 5 contributed the most to the change in wl during a change in position . a change in position from standing to sitting on a chair resulted in a change in wl of a mean value of 47% and 32.6% at the l5-s1 and l4 - 5 levels , respectively .
a change in position from standing to sitting on the floor resulted in a change in wl of a mean value of 40.2% and 37.9% at the l5-s1 and l4 - 5 levels , respectively . a change in position from sitting on the chair to sitting on the floor resulted in a change of 62.2% in wl at the l4 - 5 level .
there was more loss in wl when sitting on the floor than when sitting on the chair .
each sl below the l2 - 3 level also significantly decreased when sitting on the floor .
most of the wl is determined by the l4-s1 level , and most of the change in wl observed during a change in position is also attributed to the l4-s1 level .
when sitting comfortably on the floor , wl below the l1 - 2 level became more kyphotic and a decrease in sl was prominent at the l4 - 5 and l5-s1 levels .
this implies relaxation of the thoracic erector spinae and lumbar multifidus muscle14 ) . in comparison with the chair - sitting position , sl at the l4 - 5 level
was greatly decreased than other levels during the floor - sitting position ; this reveals high compressive loading at this level . in the case of low lumbar fusion , especially at the l4 - 5 level ,
adjacent segment hypermobility is expected when sitting on the floor . because loss of segmental motion at the l4 - 5 level is shown to be redistributed among multiple cranial segments , in most cases at the first cranial adjacent level2 ) ,
individuals used to sitting on the floor are more prone to adjacent segment hypermobility after low lumbar fusion .
akamaru et al.1 ) demonstrated that hypolordotic fusion at the l4 - 5 level caused the greatest amount of flexion - extension motion at the l3 - 4 level .
bae et al.3 ) reported that postoperative hypolordotic sl is a risk factor for adjacent segment degeneration .
we speculate that hypolordotic fusion might aggravate adjacent segment motion and degeneration in the sitting position .
surgeons should remember to avoid hypolordotic low lumbar fusion in individuals who are used to sitting on the floor .
low lumbar fusion , especially in the hypolordotic state , is highly associated with hyperflexion at the adjacent segment when sitting on the floor ; this brings about deactivation of the local lumbar stabilizing muscle and increases connective tissue strain12 ) .
deactivation of the local spinal stabilizing muscle that is known to be fatigue - resistant exerts high compressive loads on the spine7,10 ) .
hence , patients may feel uncomfortable and face difficulty when sitting on the floor after low lumbar fusion surgery .
loss of sl is associated with an increased incidence of low back pain and increased rate of degenerative changes observed at the adjacent levels . to decrease segmental motion at the adjacent segment after low lumbar fusion in the sitting position ,
it may be beneficial to fuse the lumbar spine in normal or hyperlordotic alignment1 ) .
o'sullivan et al.14 ) suggested a lumbopelvic sitting position in which participants were instructed to rotate their pelvis anteriorly to obtain a neutral lordosis in the lumbar spine and relax their thorax .
this resulted in increased coactivation of the superficial lumbar multifidus and internal oblique and is capable of providing a local stabilizing effect on the lumbopelvic region without high compressive loading .
however , this position may not be easily achieved when sitting on the floor because of ischial tuberosities .
when sitting , the spinal load is carried mainly by the ischial tuberosities15 ) , which make it difficult to rotate the pelvis anteriorly when sitting on the floor .
makhsous et al.13 ) proposed that sitting on a chair with reduced ischial support and enhanced lumbar support could decrease sitting - related low back pain .
it is presumed that lumbar support provided by a cushion for sitting on the floor helps reduce sitting load and enhances neutral lumbar lordosis by rotating the pelvis anteriorly .
contribution to the loss of lordosis when sitting on a chair and on the floor was the greatest at levels l5-s1 , and it showed relatively less influence on the change in lordosis when switching positions from sitting on a chair to sitting on the floor .
this implies hypermobility at the l5-s1 level in any sitting position , which explains the remarkable incidence of nonunion at this level6 ) . using the clinical significance of this data
, we should 1 ) explain to patients before they undergo surgery that they would experience difficulty when sitting on the floor after fusion surgery , 2 ) create greater lordotic fusion for the low lumbar spine , 3 ) recommend patients a change in lifestyle , and 4 ) perform more rigid fixation for the l5-s1 fusion . because this study included only healthy volunteers
, there exists a limitation to explain the changes of sl and wl after low lumbar fusion . we are planning to perform similar study in fusion group and expect to report this result in near future .
the results of this study suggest sitting on the floor affects the sagittal lumbar curve by decreasing lordosis at each level , especially at the l4 - 5 and l5-s1 levels . in the case of low lumbar fusion
, hyperflexion is expected at the adjacent segment when sitting on the floor . in this respect , sitting on the floor can easily aggravate lbp . to avoid this , sitting with a lordotic lumbar curve is important .
surgeons should remember to create sufficient lordosis when performing lower lumbar fusion surgery in patients with an oriental life style .
 objectiveto compare radiographic analysis on the sagittal lumbar curve when standing , sitting on a chair , and sitting on the floor.methodsthirty asymptomatic volunteers without a history of spinal pathology were recruited . 
 the study population comprised 11 women and 19 men with a mean age of 29.8 years . 
 an independent observer assessed whole lumbar lordosis ( wl ) and segmental lordosis ( sl ) between l1 and s1 using the cobb 's angle on lateral radiographs of the lumbar spine obtained from normal individuals when standing , sitting on a chair , and sitting on the floor . 
 wl and sl at each segment were compared for each position.resultswl when sitting on the floor was reduced by 72.9% than the average of that in the standing position . 
 of the total decrease in wl , 78% occurred between l4 to s1 . 
 there were significant decreases in sl at all lumbar spinal levels , except l1 - 2 , when sitting on the floor as compared to when standing and sitting on a chair . 
 changes in wl between the positions when sitting on a chair and when sitting on the floor were mostly contributed by the loss of sl at the l4 - 5 and l5-s1 levels.conclusionwhen sitting on the floor , wl is relatively low ; this is mostly because of decreasing lordosis at the l4 - 5 and l5-s1 levels . in the case of lower lumbar fusion 
 , hyperflexion is expected at the adjacent segment when sitting on the floor . to avoid this , sitting with a lordotic lumbar curve is important . 
 surgeons should remember to create sufficient lordosis when performing lower lumbar fusion surgery in patients with an oriental life style . 
INTRODUCTION
MATERIALS AND METHODS
Population
Radiographic evaluation
Statistical analysis
RESULTS
DISCUSSION
CONCLUSION