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Paper text:
postural orientation is the 
 position of body segments in relation to each other and the surrounding environment . 

postural balance is the forces that act on the body and the maintenance of equilibrium 
 during motor actions1 .
individuals 
 stabilize themselves in their environment using information from the eyes , vestibular system 
 and soles of the feet2 , 3 .
the functions of the feet involve the distribution of plantar 
 pressure , support of the body , the absorption of impact and postural adjustments for the 
 maintenance of an erect standing posture2 , 4 .
the central nervous system uses ascending 
 motor pathways that receive information from the feet to control the position of the body 
 and coordinate posture in relation to the surrounding environment5 , 6 .
posturology unites knowledge about the prevention and treatment of postural problems in 
 neurophysiology with the use of orthopedic insoles . according to bricot4and viladot9 ,
the aim of orthopedic insoles is to support the body , correct 
 deformities and improve foot function .
postural insoles simulate correction reflexes , affect 
 muscle proprioception in the feet and modify the activation of ascending proprioceptive 
 chains4 , 7,8,9 .
the aim of postural insoles is to assist in the treatment of 
 postural problems , relieve pain and treat conditions of the locomotion system ( legs , knees , 
 ankles and feet)10 .
postural insoles are 
 custom made and thermal molded in orthopedic material , such as microfoam , rigid or 
 semi - rigid rubber of different densities , polypropylene , plastazote , evazote , etc10 .
a number of studies have reported the 
 importance of insoles for improving postural balance .
systematic methods are used to avoid bias and to make possible a more objective analysis of 
 the results , facilitating a conclusive synthesis about certain interventions11 .
the aim of the present study was to perform a systematic review of the literature on the 
 effect of different insoles on postural balance .
searches were carried out of the medline , lilacs , pedro and scielo databases using the 
 keywords insole and postural balance .
the papers retrieved were evaluated by two blinded researchers employing the following 
 inclusion criteria : 1 ) design : controlled clinical trial ; 2 ) intervention : insole ; 3 ) 
 outcome : change in static postural balance ; and 4 ) year of publication : 2005 to 2012 .
the selected papers were analyzed with regard to the methodological quality using the pedro 
 scale .
this scale has 11 items for the assessment of internal validity and statistical 
 information in randomized , controlled trials .
each adequately met item contributes one point 
 to the maximal score of 10 points except item 1 , which is related to external validity .
the 
 official score of the papers described in the electronic database was used . for cases in 
 which
the manuscript was not found in this database , the evaluation was performed 
 independently by two blinded researchers .
a third researcher performed the evaluation when 
 divergences occurred in the evaluations of the first two researchers .
the search of the medline , pedro , lilacs and scielo databases led to the retrieval of 12 
 different titles and abstracts of papers on the comparison of the effect of different 
 insoles on postural balance .
all 12 papers had a minimum of 3 points on the pedro scale and 
 were therefore considered methodologically adequate ( table 1 ) .
the kinds of 
 insoles used were : vibrating insoles , textured insoles , quick - comfort insoles , insoles with 
 spikes , flat insoles with different shore a hardness , insoles with wedges and sensors and 
 balance - enhancing insoles ( table 2 ) .
with regard to data acquisition , nine papers12,13,14,15,16,17,18 , 22 , 23 
 employed balance analysis using a force plate , mainly investigating displacement from the 
 center of pressure and sway in the anteroposterior and mediolateral directions .
the 
 remaining papers analyzed postural balance using the following methods : surface 
 electromyography , an electronic version of the romberg test with a camera - based motion 
 analysis system , and a gait disturbance protocol ( table 
 3 ) .
the body needs to 
 receive information on its position in space and the surrounding environment .
this 
 information is transmitted through the neural system , which integrates sensory information 
 from the soles of the feet to determine the position and motion of the body in space with 
 information from the musculoskeletal system , which generates the forces necessary to control 
 the body24 . as points of contact between the body and ground ,
the feet contribute to the balance and 
 maintenance of posture in the standing position .
different types of insoles have been 
 developed to enhance somatosensory information from the plantar region and improve postural 
 stability .
the studies carried out by gagey et al.16 , hijmans et al.19 and priplata et al.13 used vibrating insoles and found improvements in balance and 
 oscillation velocity in the anteroposterior direction .
those vibrating insoles have a 
 mechanical noise that allows auditory feedback , with a positive effect on postural 
 stability .
the first study took into account the individual sensitivity of each patient , 
 with six vibration options ( 0 v , 10 v , 20 v , 30 v , 40 v and 50 v ) .
the second study employed 
 90 percent of the individual tactile threshold of each participant as the noise amplitude 
 parameter ; when this threshold was not reached , the maximal amplitude offered by the 
 piezoelectric elements in the insole was used ( 120 v ) .
the third study employed insoles 
 molded in viscoelastic silicone and three vibration elements denominated  tactors  ( two 
 under the forefoot and one under the heel ) ; the stimulation level was adjusted to 90% of the 
 sensory threshold of each foot .
the first study used the following : 
 texture 1  evalite pyramid eva , 3  mm in thickness , a50 shore value , black , og1549 ; texture 
 2  nora lunasoft non - slip , 3  mm in thickness , a50 shore value , black , og2250 . 

the second study used an insole with pyramid peaks for texture 1 and insoles with a convex 
 circular pattern for texture 2 .
qiu et al.22 and palluel et al.20 used insoles with rigid discs and spikes , respectively . all studies 
 report that textured insoles help reduce postural oscillations , especially in the 
 mediolateral direction , and the activation of the tibialis anterior muscle .
geffen et al.22 investigated different 
 densities : insoles measuring 8  mm in thickness , black foam rubber , with a 15 degree shore 
 value and harder insoles measuring 8  mm in thickness , multi - shape , with a 30 degree shore 
 value .
iglisias et al.13 studied the 
 effect of a soft gel insole ( softsock foot support , addison , tx , usa ) with a 6.35  mm sole of 
 solid gel and a hard insole ( a50 shore value , algeos ltd .
liverpool , uk ) with a 6.35  mm 
 surface of smooth ethylene vinyl acetate . according to geffen et al.22 ,
patients 
 with diabetic neuropathy are often prescribed insoles with a low shore value to protect the 
 feet from pressure sores .
these insoles redistribute pressure between the foot and insole , 
 thereby offering shock absorption .
however , insoles with a low shore value are less rigid 
 and lead to a reduction in the sensory input , which may result in difficulties with regard 
 to postural stability .
moreover , postural stability is expected to decline when patients use 
 shoes with thicker , softer and more elastic soles .
sungkarat et al.17 carried out a study 
 to determine whether external feedback promotes the symmetrical distribution of weight and 
 better posture control in stroke victims using insoles with wedges and set - up sensors .
the a 
 i - sample set - up consisted of a wedge insole and pedal for the non - paretic leg and a pressure 
 sensor on the paretic leg .
although not found in the literature based on the inclusion criteria , geffen et al.22 reported that magnetic insoles were used 
 to reduce postural sway due to increases in blood flow and sensory alterations in the 
 foot .
regarding the aforementioned insoles , the various authors explain that mechanoreceptors 
 respond to mechanical stimuli , including recesses and stretching of the skin , providing 
 information on texture , which allows detection of the spacing , roughness and direction of 
 the texture pattern .
thus , the principle of using textured surfaces is to increase the 
 sensory input .
based on this same principle , vibrating insoles have also been proven to 
 reduce static postural sway .
the various findings indicate effects on both static and 
 postural balance , regardless of the nature or degree of the stimulus .
a large number of studies report the advantages of orthopedic insoles , but few have 
 compared the effect of different insoles on postural balance .
the studies included in the 
 present systematic review of the literature report the benefits of insoles with regard to 
 improvements in balance and postural control . since this study is a review , it shows existing data of the usage of insoles for treatment 
 on postural balance .
it is necessary to continue studies of this research segment in order 
 to find out the most appropriate insole as well as standardize tests and evaluations of 
 balance for a better comparison .
[ purpose ] the aim of the present study was to perform a systematic review of the 
 literature on the effect of different insoles on postural balance . 
 [ subjects and methods ] 
 a systematic review was conducted of four databases . 
 the papers retrieved were evaluated 
 based on the following inclusion criteria : 1 ) design : controlled clinical trial ; 2 ) 
 intervention : insole ; 3 ) outcome : change in static postural balance ; and 4 ) year of 
 publication : 2005 to 2012 . [ results ] twelve controlled trials 
 were found comparing the 
 effects of different insoles on postural balance . 
 the papers had methodological quality 
 scores of 3 or 4 on the pedro scale . 
 [ conclusion ] insoles have benefits that favor better 
 postural balance and control .