Effect of external lumbar supports on joint position sense, postural control, and postural adjustment: a systematic review

Abstract

Purpose

To review the effects of external lumbar supports on various aspects of sensorimotor function including joint position sense (JPS), postural control, anticipatory postural adjustments (APAs), and compensatory postural adjustments (CPAs).

Methods

A systematic literature search was performed in PubMed, EMBASE, Scopus, Ovid, Cochrane library, and Web of Science. Two reviewers selected studies which assessed the effect of lumbosacral orthosis or kinesio-tape on JPS, postural control or APAs/CPAs in subjects with and without low back pain (LBP). The methodological quality of included studies was assessed using a modified version of Downs and Black’s checklist.

Results

Findings demonstrated moderate effects of lumbosacral orthosis on specific aspects of sensorimotor control including JPS and to a lesser extent standing stability. These domains were not or minimally affected by application of kinesio-tape. Both orthosis and kinesio-tape had negligible effects on APAs and CPAs.

Conclusions

The positive effects of lumbar orthosis on JPS or postural control were mostly observed in conditions where sources of proprioceptive feedback are impaired (such as LBP) or absent (standing with eyes closed on an unstable surface). However, evidence does not prove significant positive effects for the application of kinesio-tape to improve sensorimotor control.

IMPLICATIONS FOR REHABILITATION

• Wearing lumbar orthosis leads to an improvement in joint position sense.

• Postural stability seems to be affected to some extent by utilizing lumbar orthosis.

• Clinicians can administer orthosis to improve sensorimotor adaptation, especially in conditions with poor proprioception.

• Kinesio-tape had negligible effects on all domains of sensorimotor control.

• Improvement of sensorimotor function as a result of application of kinesio-tape is questionable.

Keywords:

• Low back pain
• lumbar orthosis
• kinesio-tape
• sensorimotor control
• proprioception
• posture

Introduction

When dealing with postural perturbations to the human spine, the central nervous system receives afferent inputs from proprioceptor receptors and other sensory systems such as visual or vestibular and then integrates and processes them in order to maintain postural stability [1,2]. Previous studies have frequently reported proprioception deficits in the lumbosacral region [3,4], altered feedforward and feedback mechanisms [5,6], delayed reflex response [7,8], and decreased postural stability [9] in people with low back pain (LBP). Although the direction of the causal relationship between LBP and sensorimotor impairment is not yet clear [10], the results of prospective longitudinal studies suggest an increased risk of developing an initial LBP episode in people with poor standing balance [11] or delayed-onset muscle reactions [7]. However, a reverse causal relationship may also exist; a sensorimotor disorder may be a consequence of pain or its cognitive aspects such as fear of pain [10].

Among numerous therapeutic modalities, lumbar supports, especially lumbosacral orthoses and kinesio-tape, are frequently used for prevention and treatment of LBP. No definite conclusion can be drawn regarding some of the proposed mechanisms such as changes in sensorimotor function to explain the effect of lumbar supports on LBP. Several studies have examined the efficacy of lumbosacral orthosis and kinesio-tape on different domains of sensorimotor function including proprioception (or kinesthesia), postural control and postural adjustment, the results of which, however, were contradictory. For instance, the effect of external lumbar supports on proprioception has been inconsistently reported with some studies showing a positive effect [12,13], others showing no effect [14,15], and others again showing a negative effect [12,16,17]. These inconsistent findings justify the need for a systematic review to synthesize the current evidence and to explain the variation between studies. Some previous reviews examined the efficacy of external lumbar supports [18–21]; however, none of them have specifically focused on sensorimotor function. The core outcome measures in these reviews were pain and disability. The present systematic review used a qualitative approach to synthesize the available evidence in order to assess the effects of external lumbar supports on various aspects of sensorimotor function, namely, joint position sense (JPS), postural control in standing and sitting, anticipatory postural adjustments (APAs), and compensatory postural adjustments (CPAs) in patients with LBP and healthy subjects.

Materials and methods

Inclusion and exclusion criteria

The PICOS (P: Population; I: Intervention; C: Comparison; O: Outcome; S: Study design) framework was used to frame the eligibility criteria and to define the search terms. P was defined as “healthy subjects or patients with LBP,” I as “lumbosacral orthosis or kinesio-tape,” O as “JPS, postural control or APAs/CPAs,” and S as “pure within-subjects design or combined with between-subjects design” (Table 1). The C component was not applicable.

Table 1. Summary of inclusion and exclusion criteria.

Inclusion criteria
Population	Healthy subjects or patients with LBP No restrictions on the diagnosis of LBP (nonspecific or specific) or the duration of symptoms (chronic or acute)
Intervention	Very short and/or longer-term application of any type of lumbosacral orthosis or kinesio-tape Administered alone or in combination with other modalities
Outcome	Any domain of sensorimotor control including joint position sense, postural control, anticipatory or compensatory postural adjustment For postural control, assessment of postural sway during static DLS using center of pressure derived from force platforms or measurement of static postural control using other computerized posturography devices such as Balance Master and Biodex Balance System For anticipatory and compensatory postural adjustment, only onset and/or amplitude of activity of the trunk postural muscles
Study design	Original studies where the same group of participants were evaluated with or without orthosis or kinesio-tape without a control group (“within-subjects” design) or with a control group (“mixed-subjects” design) Full-length articles in English published in peer-reviewed journals
Exclusion criteria
Population	Participants with neurological disorders
Intervention	Use of pelvic belt, thoraco-lumbosacral orthosis or thoracic support
Outcome	Measures of trunk stability, baropodometry, and measures obtained during postural tasks other than DLS
Study design	Review articles, thesis, conference proceeding and letter to editors

LBP: low back pain; DLS: double-leg stance.

Information sources and search strategy

The present systematic review was reported in accordance with guidelines outlined in the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) Statement. A systematic literature search was performed in the electronic databases of PubMed, EMBASE, Scopus, Ovid, Cochrane library, and Web of Science from the earliest possible entry until April 2021 to identify relevant studies. Literature search was completed by search in Google Scholar, citation tracking of all included articles and checking reference lists of included studies to identify additional eligible studies.

The specific search string used in PubMed is available as an online Supplementary material (Table S1). The search strategy was optimized for other databases through appropriate adjustments, and the results of search string per database were exported to EndNote.

Study selection

After completing the search process, two reviewers (F.A. and M.M.) independently screened the title and abstract of retrieved studies based on pre-identified inclusion/exclusion criteria.

Assessment of methodological quality

The two reviewers (F.A. and M.M.) assessed the methodological quality of included studies using a modified version of Downs and Black’s checklist, designed for assessing the quality of randomized and non-randomized studies. This checklist has a high internal consistency and inter-rater and intra-rater reliability [22]. The modified version consists of four domains measuring quality of reporting, external validity, internal validity, and study power (Table 2).

Table 2. Modified version of Downs and Black’s checklist to assess risk of bias of included studies.

Items	Scoring guideline
Reporting
1. Is the hypothesis/aim/objective of the study clearly described?
2. Are the main outcomes to be measured clearly described in the Introduction or Methods section?	If the main outcomes are first mentioned in the Results section, the question should be answered no.
3. Are the characteristics of the subjects included in the study clearly described?	In cohort studies and trials, inclusion and/or exclusion criteria should be given. In case-control studies, a case-definition and the source for controls should be given.
4. Are the interventions of interest clearly described?
5. Are the main findings of the study clearly described?	Simple outcome data (including denominators and numerators) should be reported for all major findings so that the reader can check the major analyses and conclusions. (This question does not cover statistical tests which are considered below).
6. Does the study provide estimates of the random variability in the data for the main outcomes?	In non-normally distributed data, the inter-quartile range of results should be reported. In normally distributed data, the standard error, standard deviation or confidence intervals should be reported. If the distribution of the data is not described, it must be assumed that the estimates used were appropriate and the question should be answered yes.
7. Have actual probability values been reported (e.g., 0.035 rather than <0.05) for the main outcomes except where the probability value is less than 0.001?
External validity
8. Were the subjects asked to participate in the study representative of the entire population from which they were recruited?	The study must identify the source population for patients and describe how the patients were selected. Patients would be representative if they comprised the entire source population, an unselected sample of consecutive patients, or a random sample. Random sampling is only feasible where a list of all members of the relevant population exists. Where a study does not report the proportion of the source population from which the patients are derived, the question should be answered as unable to determine.
9. Were those subjects who were prepared to participate representative of the entire population from which they were recruited?	The proportion of those asked who agreed should be stated. Validation that the sample was representative would include demonstrating that the distribution of the main confounding factors was the same in the study sample and the source population.
Internal validity-bias
10. Was an attempt made to blind those measuring the main outcomes of the intervention?
11. If any of the results of the study were based on “data dredging,” was this made clear?	Any analyses that had not been planned at the outset of the study should be clearly indicated. If no retrospective unplanned subgroup analyses were reported, then answer yes.
12. Were the statistical tests used to assess the main outcomes appropriate?	The statistical techniques used must be appropriate to the data. For example, non-parametric methods should be used for small sample sizes. Where little statistical analysis has been undertaken but where there is no evidence of bias, the question should be answered yes. If the distribution of the data (normal or not) is not described it must be assumed that the estimates used were appropriate and the question should be answered yes.
13. Were the main outcome measures used accurate (valid and reliable)?	For studies where the outcome measures are clearly described, the question should be answered yes. For studies which refer to other work or that demonstrates the outcome measures are accurate, the question should be answered as yes.
Internal validity – confounding (selection bias)
14. Were study subjects randomized to intervention groups?	Studies which state that subjects were randomized should be answered yes except where method of randomization would not ensure random allocation. For example, alternate allocation would score no because it is predictable. For single group designs, randomization could be considered as whether the subjects randomly assigned to the sequence of with orthosis and without orthosis?
Power
15. Did the study have sufficient power to detect a clinically important effect where the probability value for a difference being due to chance is less than 5%?	Did the study performed power calculation?

The original Downs and Black’s checklist consists of 27 items. In the modified version, items 5, 8, 9, 13, 14, 17, 19, 21, 22, 24, 25, and 26 of the original version were discarded, and a reduced checklist of 15 items was employed for scoring.

Data extraction

Information about participant’s demographic characteristics, inclusion/exclusion criteria, intervention characteristics, and test protocols was extracted from included articles by the first reviewer (F.A.) using a data extraction form, and verified by the second reviewer (M.M.).

Data analysis

Mean and standard deviation (SD) of all outcome measures and the number of participants per group were extracted by the first author (F.A.). When the data were presented separately for male and female participants in a study, the formula suggested by the Cochrane Handbook for Systematic Reviews of Intervention was used to combine mean, SD, and number of subjects of the two subgroups into a single group. Where SEM was only reported, SD was calculated using the formula: $\mathrm{SD}=\mathrm{SEM}\times \surd N.$ When range and median were only available, mean and SD were calculated using a method devised by Hozo et al. [23]. When numerical data were only presented in figures, we used WebPlotDigitizer (https://automeris.io/WebPlotDigitizer) to extract the mean and SD or SEM from figure images.

For JPS error and traditional center of pressure (COP) time-series measures, the results of original studies were replicated using bar charts to compare single groups before and after wearing external lumbar support. The study results were sub-grouped in accordance with the type of intervention (tape and/or orthosis) and the length of intervention (immediate and/or longer-term). The immediate effect was defined as the changes in the outcome measures observed in a single session immediately after application of external lumbar supports, whereas longer-term effect was characterized as the effect measured after a course of treatment, either short-term (hours or days) or long-term (months). Mean, SD, and significance results for other measures of postural control and postural adjustments were presented in the tables.

Results

Literature search

Screening titles and abstracts yielded 40 potentially eligible studies out of 2309 retrieved studies. Detailed review of their full text resulted in the exclusion of 13 studies [24–36]. Hand search of reference list of included studies did not yield further study. From the remaining 27 studies, eight studies were included for review of JPS, 16 studies for postural control, and five studies for APAs/CPAs with one study reporting both JPS and postural control [15] and another one reporting both JPS and APAs/CPAs [37] (Figure 1).

Figure 1. Study selection flowchart.

Read the detailed description of this figure

Identification, screening, eligibility, and inclusion of studies for the review.

Characteristics of studies

Overview of participants’ characteristics

Of the 27 included studies, 11 studies examined healthy individuals [13,15,16,38–45], 12 studies examined only LBP patients [37,46–56], and four studies evaluated both healthy individuals and LBP patients [12,14,17,57] (Table 3). With the exception of one study in which participants had lumbar discopathy [51], most studies examined patients with non-specific LBP.

Table 3. Study design, demographic, inclusion/exclusion criteria, and intervention characteristics of all included studies.

Author	Inc/exc criteria	Participants demographics (age; sex [m/f]; height [cm], weight [kg]; BMI [kg/m^2])	Number and health status of subjects	Type of low back pain, duration and intensity of pain and disability	Type of intervention	Associated intervention	Length of intervention	Time to assessment
Abbasi et al. [56]	Non-specific chronic LBP lasting more than 3 months; pain between 12th rib and the gluteal folds; no history of neurological deficits, sciatica or other radicular involvement, nerve root compression, spinal surgery, rheumatic disease, diabetes, mental disorders, pregnancy, lower extremity injuries, neuromuscular disease, allergic reaction to taping	44.3 ± 3.6; 6/9; NR; NR; 24.9 ± 3.5	15 LBP	Non-specific LBP; >3 months; Short-Form McGill Pain Questionnaire: 18.2 ± 6.9; VAS (0-10): 5.6 ± 1.4; VAS on the test day: 2.2 ± 0.7; ODI: 21.1 ± 6.1	Star shape application kinesio-tape	No	72 h	Before, and 72 h after intervention
Abbasi et al. [46]	Non-specific back pain lasting more than 3 months; pain radiating no further than buttock; at least 30 on the 100 mm NRS; no history of neurological signs such as sensory deficits, motor paralysis, vestibular system impairment, dizziness, medication with known effects on balance	41.95 ± 5.46; 10/10; NR; NR; 21.91 ± 2.6	20 LBP	Non-specific LBP; >3 months; NRS (0-100 mm): 47.25 ± 18.09; ODI: 20.91 ± 11.07	X shape application kinesio-tape	No	24 h	Before, immediately and 24 h after intervention
Azadinia et al. [47]	20–55 years old; minimum 1-year history of LBP; incidence of at least one recurrent episode of pain in the last 6 months that lasted at least 1 week and needed treatment or sick leave; pain of a semi-continuous nature and various severity depending on the situation; a minimum ODI score of 6; no non-musculoskeletal back pain, neurological symptoms due to nerve root compression, history of vestibular disorders, diabetes, and an observed spinal deformity, lower limb length discrepancy, consumption of sedatives or substances affecting the central nervous system 24 h prior to the test	27.47 ± 5.70; 8/9; 172.29 ± 10.14; 68.91 ± 13.19; NR	17 LBP	Non-specific LBP; 4.13 ± 3.46 years; VAS on the test day (0–10): 3.77 ± 1.97; ODI: 22.95 ± 6.58	Non-extensible LSO	No	Immediate effect	With and without LSO
Azadinia et al. [48]	20–55 years old; history of LBP for at least 1 year with a semi-continuous nature of pain or have had at least one episode of LBP over the past 6 months lasting for 1 week and requiring treatment or sick leave; disability score greater than 6; no non-musculoskeletal LBP, neurological symptoms caused by nerve root compression, severe spinal deformities, history of spinal surgery, respiratory disease, systemic infections, neurological disease, diabetes, pregnancy, history of vestibular disorders, un-corrected visual impairments, lower limb length discrepancy, lower limb musculoskeletal disorders, using LSO during the past 6 month, recent physical therapy intervention, tranquillizers or other substance affecting the central nervous system within 24 h before the trial	27.45 ± 5.13; 9/13; 169.68 ± 10.22; 66.26 ± 12.91; NR	22 LBP	Non-specific chronic LBP; 4.19 ± 3.09 years; VAS on the test day (0-10): 3.60 ± 2.05; ODI: 22.28 ± 6.50	Non-extensible LSO	Routine physical therapy twice a week for 4 weeks	4 weeks (long day except sleeping time)	Before and immediately after intervention
Azadinia et al. [49]	20–55 years; >12-month history of LBP; >1 recurrent episode lasting one week during the last 6 months that required treatment or sick leave and/or a semi-continuous pain; disability score greater than 6; no non-musculoskeletal LBP, pain spreading down the gluteal fold, neurologic symptoms due to nerve root compression, history of vestibular disorders, neurological disease, uncorrectable visual impairments, respiratory diseases, pregnancy, diabetes, history of spinal surgery; inflammatory disease, systemic infections, pathologies and severe deformities of spine, lower limb length discrepancy, lower limb musculoskeletal disorders, recent physical therapy intervention, history of use of LSO during the last 6 month, consuming sedative and other substances affecting balance or central nervous system	27.3 ± 5.3; 8/12; 170.3 ± 10.5; 66.8 ± 13.3; NR	20 LBP	Non-specific LBP; 4.31 ± 3.21 years; VAS on the test day (0–10): 3.66 ± 2.15; ODI: 22.63 ± 6.49	Non-extensible LSO	Routine physical therapy twice a week for 4 weeks	4 weeks (long day except sleeping time)	Before and immediately after intervention
Bae et al. [54]	LBP duration for more than 12 weeks; no history of lumbar surgery, structural malformation or musculoskeletal disease, allergy to kinesio-tape; not received lumbar muscles exercise for the past 3 months; not experienced tape application before; VAS or ODI scores 6 or higher; not taking adrenocortical hormone or pain alleviation medication	53.6 ± 2.1; 5/5; 165.82 ± 6.5; 71.3 ± 9.3; 21.45 ± 3.13	10 LBP	NR; 13.2 ± 3.4 months; VAS (0–10): 7.83 ± 0.38; ODI: 16.32 ± 5.13	Four I stripe, star shape kinesio-tape	Ordinary physical therapy, three times per week, for 12 weeks	Three times per week, for a total of 12 weeks	Before (without tape) and after 12 weeks
Boucher et al. [14]	Lumbar or lumbosacral pain for at least 4 weeks (non-acute phase); no radicular pain below the knee, pelvic or spinal surgery, specific lumbar pathology (fracture, infection or tumor), scoliosis, systemic or degenerative disease; BMI >30 kg/m^2; high blood pressure; history of neurological condition other than that related to back pain; receiving anxiolytic medication, anticonvulsants, or antidepressants, receiving medication that could affect neuronal excitability; sacroiliac pain	LBP: 38.6 ± 10.3 (male), 46.3 ± 11.2 (female); 19/19; 175.5 ± 5.3 (male), 162.3 ± 8.1 (female); 77.0 ± 9.7 (male), 64.8 ± 10.8 (female); 25.0 ± 2.9 (male), 24.4 ± 2.9 (female) Healthy: 39.7 ± 13.8 (male), 39.8 ± 13.5 (female); 9/10; 175.9 ± 7.4 (male), 164.6 ± 5.4 (female); 77.1 ± 10.9 (male), 62.3 ± 8.4 (female); 24.8 ± 2.2 (male), 22.9 ± 2.8 (female)	38 LBP and 19 Healthy	Non-specific LBP; >4 weeks; NRS (0–10): 1.7 ± 0.4 (males), 1.2 ± 0.3 (females); RMDQ (0–24): 6.42 ± 3.72 (males), 3.63 ± 2.52 (females)	Lumbar belt (extensible and non-extensible)	No	Immediate effect	With and without LSO
Cholewicki et al. [40]	No history of LBP or neurological disorders	26 ± 8; 11/3; 180 ± 13; 81 ± 14; NR	14 healthy	NA	LSO	No	At least 3 h a day for 3 weeks	Days 0, 7, and 21, with and without LSO
Cholewicki et al. [38]	NR	27.9 ± 9.8 (male), 22.1 ± 2.1 (female); 12/11; 179 ± 8 (male), 166 ± 7 (female); 77.0 ± 4.0 (male), 55.6 ± 4.3 (female); NR	23 healthy	NA	LSO	No	Immediate effect	With and without LSO
Cholewicki et al. [16]	No history of LBP or neurophysiological disorders	26 ± 8; 11/3; 180 ± 13; 81 ± 14; NR	14 healthy	NA	LSO	No	3 h a day for 3 weeks	Days 0, 7, and 21, with and without LSO
Ghofrani et al. [53]	Localized LBP; feeling pain intensity less than 4 based on VAS; lasting pain more than 6 months and radiating no further than the buttock; no previous history of sciatica or other radicular involvement; no history of vestibular and neurological disease, no hip, knee, ankle or foot problems	24.8 ± 3.8; NR; 166 ± 7.7; 64.8 ± 12; 23.3 ± 2.9	16 LBP	NR; >6 months; VAS (0–10): <4	Lumbosacral belt	No	Immediate effect	With and without LSO
Hidalgo et al. [17]	LBP: non-specific chronic LBP (≥6) without pain radiating into the leg Healthy: no history of LBP in the 12 months prior LBP and healthy: no vestibular disease, pregnancy, diabetes, neurologic disorders, specific LBP, history of musculoskeletal system surgery in the low back area	LBP: 33.8 ± 7.5; 5/5; NR; NR; 22.4 ± 2.9 Healthy: 27.7 ± 9.7; 14/14; NR; NR; 23.1 ± 2.4	10 LBP 28 healthy	Non-specific LBP; 11.4 ± 4.7 months; VAS (0–10): 3.4 ± 0.9	Kinesio taping: two bands from T12 to S2, and two other bands in a cross over L3	No	Immediate effect	With and without tape
Jassi et al. [55]	18–60 years old; non-specific LBP in the last 3 months and/or pain in at least half of the days in the past 6 months; mechanical pain behavior caused by postures, activities, and movements like bending and functional movement tasks; pain intensity ≥3; ODI >14%	32.08 ± 12.9; 21/19; NR; NR; NR	40 LBP	Non-specific LBP; >3 months; NRS (0-10 cm): 4.65 ± 1.76; ODI: 10.23 ± 5.37	Star shape application of kinesio-tape	No	7 days	Before, immediately, after 3 days, after 7 days, and after 1 month follow up
Kang et al. [52]	LBP for more than 3 months; no vestibular disease or disease in the ear, nose, and throat, neuropsychiatric impairments, visual handicaps or episode of dizziness or mild headache	59.4 ± 5.4 (soft LSO), 57.3 ± 6.2 (rigid LSO); NR; 161.1 ± 4.72 (soft LSO), 161.8 ± 7.79 (rigid LSO); 60.9 ± 7.46  (soft LSO), 60.4 ± 7.85 (rigid LSO); NR	20 LBP N = 10 (soft LSO) N = 10, (rigid LSO)	NR; >3 months; VAS (0–10): 3.3 ± 1.64 (soft LSO), 3.8 ± 1.75 (rigid LSO)	Soft LSO, rigid LSO	No	4 weeks	1 day after and 4 weeks after wearing LSO
Lavender et al. [41]	No back pain during the past year	22–47; 10/8; 176 ± 7 (males), 163 ± 7 (females); 74.3 ± 10.5 (males), 58.8 ± 7.1 (females); NR	18 healthy	NA	Lifting belt loose and tensioned conditions	No	Immediate effect	Loose and tensioned lifting belts
Mathias and Rougier [45]	20–23 years old; no history of neurological disorders, trauma or chronic or occasional back/leg pain	20–23; 6/6; 171 ± 9; 62 ± 9; NR	12 healthy	NA	Normal back brace and lordotic back brace	No	Immediate effect	With and without brace
McNair and Heine [13]	No previous history of LBP	26.3 ± 6; 20/20; 173 ± 9.6 ; 70.9 ± 11.1; NR	40 healthy	NA	Neoprene lumbar brace	No	Immediate effect	With and without LSO
Mi et al. [57]	LBP: history of non-specific LBP lasting at least 6 months; no pain below the gluteal fold or associated with radicular syndrome, cauda equina syndrome or any other condition that might affect balance performance, such as vestibular pathologies; infection, tumor, osteoporosis, fracture, structural deformity, inflammatory disorder Healthy: no self-reported neurological or musculoskeletal impairment, pain or disability, the presence of known sensory or neurological disorders, previous back surgery, active lower limb musculoskeletal pathology, the use of any medication the affected their postural control, those with a history of LBP within 6 month or any known balance problems were excluded	LBP: 61.14 ± 2.72; 8/20; 156.86 ± 3.44; 63.21 ± 3.51; 25.71 ± 1.52 Healthy: 59.43 ± 2.97; 6/22; 158.64 ± 4.05; 65 ± 4.07; 25.89 ± 2.28	28 LBP 28 Healthy	Non-specific LBP; 52.64 ± 8.86 months; VAS (0–10): 4.14 ± 0.83	LSO	No	Immediate effect	With and without LSO
Munoz et al. [43]	No history of neurological disorders, trauma or chronic or occasional back or leg pain	23.3 ± 1.9; 6/6; 175 ± 10; 65.3 ± 6.2; NR	12 healthy	NA	Neutral and lordotic lordactive lumbar orthosis	No	Immediate effect	With and without LSO
Munoz et al. [51]	Discopathic LBP	44.3 ± 8.9; 4/7;170 ± 10; 67.3 ± 13.2; NR	11 LBP	Degenerative lumbar discopathy; no sign of acute pain	Loractive lumbar brace	No	Immediate effect	With and without orthosis
Newcomer et al. [12]	LBP: maximal pain for at least 6 months between L1 and gluteal folds; average pain intensity in the past week at least 5/10; no very severe pain Healthy: no history of LBP for more than 3 months in duration; free of LBP for at least the previous year; no pregnant and lactating women, history of previous back surgery, vertebral compression fracture, neurological deficit, current lower extremity symptoms, and symptoms of vertigo or dizziness.	LBP: 44.2 ± 10.6; 9/11; NR; NR; NR Healthy: 39.8 ± 12.7; 9/11; NR; NR; NR	20 LBP 20 healthy	NR; >6 months; pain intensity (0–10) during last week: >5/10	Lumbar support	No	2 h	Before and after intervention, with and without LSO
Reeves et al. [44]	Free of any back pain for at least 1 year, no neurological or musculoskeletal problems	23.5 ± 5.7 (males), 20.5 ± 1.7 (female); 6/4; 179 ± 12 (males), 167 ± 8 (females); 77 ± 4.5 (males), 55.6 ± 4.4 (females); NR	10 healthy	NA	Lumbosacral brace	No	Immediate effect	With and without belt
Ruggiero et al. [15]	20–24 years old	NR; 0/12; NR; NR; NR	12 healthy	NA	Kinesio tape applied with stretch: A single strip of kinesio tape in the horizontal direction at the L1–L2 vertebral level	No	30 min	Before (without tape) and immediately after (with and without tape) intervention
Samani et al. [37]	25–55 years old; persistence pain for at least 3 months; pain intensity in the previous month at least 4; disability level at least 20; lumbar flexion and extension range of motion at least 50% normal; ability to walk unaided without assistive devices; no acute trauma, vertebral fracture, history of lumbar surgery, history of any type of fracture or dislocation in the lower extremities and pelvis, pregnancy, symptoms of neoplasm or pathologic disease, evidence of infectious disease, inflammatory disease, neurological disease, history of mental illness	High pressure LSO: 37.3 ± 6.07; 1/12 ; 161.84 ± 4.93; 57.07 ± 5.04; 21.87 ± 2.46 Normal pressure LSO: 35.85 ± 7.08; 3/11; 163.21 ± 9.18; 58.28 ± 9.65; 21.08 ± 2.24	42 LBP	Non-specific LBP; >3 months; VAS (0–100): 76.84 ± 11.02 (high pressure LSO), 71.78 ± 10.43 (normal pressure LSO); modified ODI (0–100): 39.69 ± 10.41 (high pressure LSO), 38.85 ± 8.31 (normal pressure LSO)	Soft LSO at normal pressure and 50% increased pressure	Nonsteroidal anti-inflammatory drugs	4 h a day for 4 weeks	Before and after 4 week intervention; without LSO
Toprak Celenay and Ozer Kaya [50]	20–65 years old; non-specific LBP; no history of surgery related to lumbar spine, having scoliosis, a neurological disease, a rheumatologic disease, pregnancy, being subjected to any intervention including exercise, physical therapy or medication during the study, having any contraindications against the use of taping	53 ± 10.69; 27/74; NR; NR; 31.52 ± 5.57	101 LBP	Non-specific chronic LBP; ODI pain score (0–5), median (range): 2 (0–5); ODI (0–100%), median (range): 18 (1–38)	Kinesio taping: On both sides of the paravertebral muscles with muscle technique; On sacrum with ligament technique	No	45 min	Before and after intervention
Toprak Celenay et al. [39]	18–25 years old; no disc herniation, spinal pain, spinal deformity, history of spinal surgery, vestibulopathy, musculoskeletal injuries related to ankle, knee, and hip joints, orthopedic and/or neurological problems, and allergy to kinesio-tape	21 ± 3.04; 13/14; NR; NR; 23.4	27 healthy	NA	Kinesio tape (on both sides of the abdominal and sacrospinal muscles)	No	60 min	Before and 60 min after intervention
Voglar and Sarabon [42]	No history of LBP in last 6 months that would require sick leave or limit function for more than 3 days; no known neurological disorders or sensory deficits	23.4 ± 3.5; 8/4; 181 ± 9; 74.8 ± 13.1; NR	12 healthy	NA	Experimental group: facilitation kinesio tape over the paravertebral muscles; Control group: sham application tape in a horizontal fashion over the lumbar spine	No	1 hour	Before (without tape) and 60 min after tape application (with tape)

NR: not reported; BMI: body mass index; LBP: low back pain; VAS: Visual Analogue Scale; NRS: numeric rating scale; ODI: Oswestry Disability Index; RMDQ: Roland-Morris Disability Questionnaire; LSO: lumbosacral orthosis.

All but three studies [15,41,45] reported the age range of the participants, ranging from 18 to 65 years. Fourteen studies reported pain duration [12,14,17,37,46–49,52–57] with pain lasting at least >3 months in all studies with the exception of one where patients had LBP with at least 4-week duration [14]. When using 0–10-point pain rating scales, pain intensity varied from 1.5 to 7.7 between studies. The LBP-related disability level was evaluated by Roland-Morris Disability Questionnaire (RMDQ) [14] and Oswestry Disability Index (ODI) [37,46–50,54–56]. The mean RMDQ and ODI disability scores were 5.02 and 21.5% (16.3–39.3%), respectively, indicating the inclusion of patients with mild to moderate functional disability in these studies. The length of intervention varied from a few minutes to 12 weeks.

JPS

Description of intervention and outcome measures

Eight studies evaluated the effect of external supports on JPS. Of the five studies evaluating the effect of orthosis, one study used rigid orthosis [16] and others used soft and/or semi-rigid orthosis, with two studies examining only the immediate effects [13,14], one assessing only longer-term effects (4 weeks [37]) and two assessing both immediate and longer-term effects (2 h [12] and 3 weeks [16]) (Table 3). Of the three studies examining the effect of kinesio-tape [15,17,56], one assessed the immediate effects [17] and the two others longer-term effects (30 min [15] and 3 days [56]). Out of eight studies, three studies included only healthy individuals [13,15,16], two studies [37,56] only patients with LBP and the other three studies [12,14,17] both healthy individuals and patients with LBP.

Since all eight studies measured active JPS using absolute error (AE) as an outcome measure (Table 4), only AE results were presented in the bar plots. JPS was measured in sitting position in five studies [14–17,37] and in standing position in three studies [12,13,56]. In two studies, the target was set in neutral-spine-posture [15,16] by returning from flexion in one study [15] and from axial rotation in the other one [16]. The target was set at a position far from neutral-spine-posture, i.e., flexion in six studies [12,13,15,17,37,56], extension in three studies [12,37,56], lateral bending in one study [12], and rotation in one study [14].

Table 4. Measurement protocol of studies investigating the effects of orthosis and kinesio-tape on JPS.

Author	Method of joint position sense measurement (active/passive)	Equipment/ instrument	Test position	Movement performed	Movement velocity	Target position	Target position presentation method	Number of practice trials	Number of measurement trials	Outcome measure (absolute/constant, variable error)
Abbasi et al. [56]	Active	Bubble inclinometer; one inclinometer was placed at T12–L1, and the other one located over the S1	Standing	Flexion, Extension	NR	45° and 60° flexion from neutral spinal posture 15° extension from neutral spinal posture	NR	1	3	AE; CE
Boucher et al. [14]	Active	Custom-built apparatus to produce passive motion of the lumbar spine in the transverse plane. The upper body was fixed to the backrest with a 4-point seatbelt, while the seat was driven by a stepper motor at a steady slow rate	Sitting (EC)	Rotation	2°/s	10° left axial rotation from neutral trunk position 10° right axial rotation from neutral trunk position	Press the hand-held button	2 per direction	10 per belt condition (5 per direction)	AE; CE; VE; total variability
Cholewicki et al. [16]	Active and passive	A specially built apparatus to produce passive motion of the lumbar spine in the transverse plane. The upper body was fixed to the backrest with a 4-point seatbelt, while the seat was driven by a stepper motor at a steady slow rate	Sitting	Trunk axial rotation	Passive movement: 0.2°/s	Neutral trunk position from 20° rotation	Pressing the switch	NR	8 per active and passive JPS measurement (4 per direction)	AE; CE; VE
Hidalgo et al. [17]	Active	Optoelectronic device (The Elite 3D track-system) with markers placed on S2 and T12	Sitting (EC)	Flexion	Subject’s self-selected speed	30° trunk flexion from neutral trunk position	NR	NR	10	AE, VE
McNair and Heine [13]	Active	Electrogoniometer	Standing	Flexion	NR	6 targets throughout the trunk flexion range of motion from neutral trunk position	NR	NR	NR	AE; CE; VE
Newcomer et al. [12]	Active	3-space tracker with 2 magnetic sensors placed over T1 and S1	Standing (EC)	Flexion; extension; right side-bending; left side-bending	5 s to reach target	30%, 60%, and 90% of the maximal ROM (in each direction) from neutral trunk position	NR	NR	NR	AE
Ruggiero et al. [15]	Active	Opto-electronic markers (Optotrak 3D Investigator, Northern Digital, Waterloo, Canada) placed over the spine at the upper sacral (S1), lower thoracic (T12) and mid-thoracic (T6) vertebral levels	Sitting in a kneeling chair	Extension	NR	Neutral trunk position from 45° flexion 45° trunk flexion from full flexion	NR	NR	3	AE
Samani et al. [37]	Active	Isokinetic dynamometer	Sitting (EC)	Flexion and extension	2°/s	30° trunk flexion from neutral trunk position 15° trunk extension from neutral trunk position	Press the stop bottom	3 trials	NR	AE

NR: not reported; AE: absolute error; CE: constant error; VE: variable error; EC: eyes closed.

Difference between pre-test/intervention and post-test/intervention

The immediate effects of orthosis were examined in 14 experimental conditions (i.e., n = 14) contributed by four studies (Figure 2). JPS error was reduced (JPS improved) by wearing orthosis in a total of five conditions related to two studies. In conditions with improved JPS, the participants were either LBP patients (n = 3, one study) or healthy individuals (n = 2, two studies). In the other 14 experimental conditions investigating the longer-term effects (n = 14, three studies), wearing orthosis was associated with improvement (n = 3, one study) in LBP patients, or deterioration of JPS (n = 3, two studies) in healthy subjects.

Figure 2. Bar plot representing the immediate and longer-term effect of lumbar orthosis on absolute JPS error in healthy and LBP people.

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The bar chart shows the effect of lumbar orthosis on JPS. Of 14 conditions examining the immediate effects (contributed by four studies), five conditions (two studies) were associated with improvement of JPS in either LBP patients (one study) or healthy individuals (two studies). In the other 14 experimental conditions investigating the longer-term effects (contributed by three studies), JPS improved in a total of three conditions (one study) in LBP patients and deteriorated in three other conditions (two studies) in healthy subjects.

The two experimental conditions related to a single study investigating the immediate effect of kinesio-tape in LBP patients (n = 1) or healthy subjects (n = 1) showed that kinesio-tape was associated with increased JPS error (Figure 3). In the other five conditions contributed by two studies examining the longer-term effects, no significant differences were found.

Figure 3. Bar plot representing the immediate and longer-term effect of kinesio-tape on absolute JPS error in LBP and/or healthy people.

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The bar chart shows the effect of kinesio-tape on JPS. Of two conditions examining the immediate effects (contributed by one study), both were associated with increased JPS error, either in LBP patients or healthy individuals. In the other five conditions examining the long-term effects (contributed by two studies) in either LBP or healthy subjects, no significant differences were found.

Postural control

Description of intervention and outcome measures

Sixteen studies [15,38,39,43–53,55,57] evaluated the effect of orthoses (n = 11) or kinesio-tape (n = 5) on postural control (Table 5). Of the 11 studies which used orthosis, four studies administered a rigid orthosis [43,45,51,52] and others used soft and/or semi-rigid orthoses. Eight of these 11 studies examined the immediate effect [38,43–45,47,51,53,57]; the length of intervention in studies examining longer-term effects was 4 weeks [48,49,52]. The tape application method was inconsistent between the five studies administering kinesio-tape [15,39,46,50,55]. The length of intervention varied from a few minutes to 7 days. Six out of the 16 studies included only healthy subjects [15,38,39,43–45], one study [57] both healthy subjects and LBP patients, and nine other studies only LBP patients [46–53,55].

Table 5. Measurement protocol of studies investigating the effects of orthosis and kinesio-tape on postural control.

Author	Test position (sitting/standing)	Equipment	Type of sensory manipulation (visual/proprioceptive/vestibular)	Duration of measurement trials (s)	Number of measurement trials	Outcome measure
Abbasi et al. [46]	Standing	Force platform	EO; EC	20	2	SD amplitude (AP and ML), RMS velocity (total, AP and ML)
Azadinia et al. [47]	Standing	Force platform	Firm surface: EO, EC Soft surface: EC	60	3	Area (95% confidence ellipse), mean total velocity, SD amplitude (AP and ML)
Azadinia et al. [48]	Standing	Force platform	Firm surface: EO, EC Soft surface: EC	60	3	Sample entropy (AP and ML), correlation dimension (AP and ML), determinism% (AP and ML)
Azadinia et al. [49]	Standing	Force platform	Firm surface: EO, EC Soft surface: EC	60	3	Area (95% confidence ellipse), mean total velocity, SD velocity (AP and ML), phase plane portrait (AP, ML, total)
Cholewicki et al. [38]	Sitting	Force platform	Unstable surface, EO	20	3	Mean velocity (AP, ML, and total)
Ghofrani et al. [53]	Standing	Force platform	EO; EC	30	3	Area; AP and ML displacement; total mean velocity
Jassi et al. [55]	Standing	Force plate	Firm surface: EO, EC Soft surface: EO, EC	40	3	Mean sway speed between AP, ML directions, COP area, RMS in AP and ML directions
Kang et al. [52]	Standing	Biodex Balance System	NR	NR	NR	Overall stability index; AP stability index; ML stability index
Mathias and Rougier [45]	Sitting	Force platform	EC	32	6	Area (ellipse); variance of the COP position (AP, ML); Mean velocity; Mean position (AP, ML)
Mi et al. [57]	Standing	Neurocom International Balance Master System	Firm surface: EO, EC Soft surface: EO, EC	10	3	COP sway velocity
Munoz et al. [43]	Sitting	Force platform	Stable, slightly unstable (seesaws with long radius) and highly unstable (seesaws with short radius) surface; EC	64	2	Variance of COP displacement (AP); Fractional Brownian motion parameters (Δt, Δx^2, Hll, Hcl)
Munoz et al. [51]	Standing	Force platform	EC	64	Not clear	Mean COP position; area (90% confidence interval); fractional Brownian analysis (Δt, Δx^2, Hll, Hcl)
Reeves et al. [44]	Sitting	Hemisphere located on a force platform	Unstable surface: EO, EC	20	3	COP velocity
Ruggiero et al. [15]	Sitting	Force platform	Unstable surface (balancing board), EO	40	3	Maximum excursion (AP, ML); RMS excursion (AP and ML); maximum velocity (AP and ML); Mean absolute velocity (AP and ML)
Toprak Celenay et al. [39]	Standing	Force platform	EO; EC	30	NR	Area (ellipse)
Toprak Celenay and Ozer Kaya [50]	Standing	Biodex Balance System	Unstable surface, EO	32	NR	Static overall stability index; static AP stability index; static ML stability index; dynamic overall stability index; dynamic AP stability index; dynamic ML stability index

NR: not reported; EO: eyes open; EC: eyes closed; AP: anteroposterior; ML: mediolateral; SD: standard deviation; RMS: root mean square; COP: center of pressure.

Out of 16 studies, 11 studies assessed postural control during standing [39,46–53,55,57] and five studies during sitting [15,38,43–45]. In all 11 studies, postural control was assessed during standing on firm surface. Additionally, proprioceptive feedback was manipulated in five of these studies by standing on foam surface [47–49,55,57]. The effect of orthoses or kinesio-tape on the postural control has been evaluated in either eyes-open (EO) [50,52] or eyes-closed (EC) condition [51] or both EO and EC conditions [46–50,53,55,57]. Among studies assessing sitting posture, four studies evaluated postural control while sitting on an unstable surface in EO (n = 2) [15,38], EC (n = 1) [43], or in both EO and EC (n = 1) [44] conditions. One study investigated the postural control in EC condition while sitting on a stable surface [45].

The most commonly used COP parameters to quantify postural sway in the included studies were sway area, amplitude, and velocity. Where both sway amplitude and velocity were available, only sway velocity measures were included as they are more reliable [58] and represent both spatial and temporal aspects of COP oscillations; otherwise, sway amplitude measures were included.

Difference between pre-test/intervention and post-test/intervention: standing

A decrease in the amount of COP fluctuations was found in three conditions out of 15 experimental conditions contributed by four studies investigating the immediate (n = 6, three studies) and/or longer-term (n = 9, one study) effects of orthosis in LBP patients (Figure 4). All three conditions were related to a single study assessing longer-term effects of orthosis on postural stability tasks while standing on foam with EC.

Figure 4. Bar plot representing the immediate and/or longer-term effect of lumbar orthosis on standing stability (COP velocity (upper panel) and area (lower panel)) in LBP subjects. Asterisks indicate significant differences. RSEO: rigid-surface eyes-open; RSEC: rigid-surface eyes-closed; FSEO: foam-surface eyes-open; FSEC: foam-surface eyes-closed.

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The bar chart shows the effect of lumbar orthosis on standing stability. Of 15 conditions (contributed by four studies) examining the immediate (three studies) and/or longer-term effects (one study) in LBP patients, three conditions were accompanied with a decrease in COP fluctuations; all these three conditions were related to a single study assessing longer-term effects on postural stability while standing on foam with EC.

The immediate and or longer-term effects of kinesio-tape on standing postural control have been investigated in 22 conditions contributed by three studies, but no significant change was observed in any of the testing conditions (Figure 5).

Figure 5. Bar plot representing the immediate and longer-term effect of kinesio-tape on standing stability in LBP (upper panel) and the longer-term effect in healthy subjects (lower panel). RSEO: rigid-surface eyes-open; RSEC: rigid-surface eyes-closed; FSEO: foam-surface eyes-open; FSEC: foam-surface eyes-closed. In the study of Toprak Celenay and Ozer Kaya [50], mean and SD were estimated on the basis of range and median values. Jassi et al.: mean sway velocity between AP and ML direction.

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The bar chart shows the effect of kinesio-tape on standing stability. No change was observed in any of 22 conditions (contributed by three studies) examining the immediate and long-term effects in LBP patients (two studies) and long-term effects in healthy individuals (one study).

Additional variables

Assessment of the immediate effects of orthosis on standing postural control using NeuroCom Balance Master showed reduced COP velocity (quantified in degrees/second) in the most challenging conditions (i.e., standing on foam surface with EO and EC) in both LBP patients and healthy controls [57] (Table S2). Longer-term effects of both soft and rigid orthoses were examined in LBP patients using the Biodex Balance System, and the results showed a decrease in mediolateral stability index (MLSI) and overall stability index (OSI) in the rigid orthosis group and a decrease in anteroposterior stability index (APSI), MLSI, and OSI in the soft orthosis group [52]. No significant changes were found when longer-term effects of orthosis on the dynamical structure of COP were examined in LBP patients [48].

Longer-term use of kinesio-tape reduced static APSI and OSI obtained from Biodex Balance System in LBP patients [50].

Difference between pre-test/intervention and post-test/intervention: sitting

Significant changes were found in three out of a total of 13 conditions contributed by four studies examining the immediate effects of wearing orthosis on sitting postural stability in healthy subjects (Figure 6). The changes included a decrease in the COP mean velocity during sitting on the stable surface with EC (n = 2, one study) or an increased COP variance during sitting on a highly unstable surface with EC following wearing a lordotic LSO (n = 1, one study).

Figure 6. Bar plot representing the immediate effect of lumbar orthosis on sitting stability (COP velocity (upper panel) and variance (lower panel)) in healthy people. Asterisks indicate significant differences. SSEC: stable-surface eyes-closed; USEO: unstable-surface eyes-open; USEC: unstable-surface eyes-closed.

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The bar chart shows the effect of lumbar orthosis on sitting stability. Of 13 conditions (contributed by four studies) examining the immediate effects in healthy subjects, three conditions were associated with either a decrease (one study) or increase (one study) in COP fluctuations.

Three conditions from six conditions related to a single study examining the longer-term effects of kinesio-tape application on sitting postural stability found kinesio-tape application to be associated with reduced COP variables (Figure 7).

Figure 7. Bar plot representing the longer-term effect of kinesio-tape on sitting stability with eyes-open in healthy people. Asterisks indicate significant differences.

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The bar chart shows the effect of kinesio-tape on sitting stability. Of six conditions (contributed by a single study) examining the longer-term effects on sitting stability with EO in healthy individuals, three conditions were associated with a reduction in COP fluctuations.

APAs and CPAs

Description of intervention and outcome measures

Five studies [37,40–42,54] examined the effect of orthoses (three studies) or kinesio-tape (two studies) on APAs and/or CPAs (Table 6). Among studies examining the efficiency of orthosis, two studies assessed the longer-term effects by utilizing a rigid orthosis applied for 3 weeks [40] or a semi-rigid orthosis in combination with NSAIDs for 4 weeks [37]. The only study which examined the immediate effects of orthosis used soft elastic belts [41]. Two of these five studies evaluated the effect of kinesio-tape alone [42] or in combination with routine physical therapy [54], but with inconsistent methods of taping. The intervention lasted one hour in one of the studies [42], and 12 weeks in another one [54]. Of these five studies, the participants were healthy individuals in three studies [40–42] and chronic LBP patients in two studies [37,54].

Table 6. Measurement protocol of studies investigating the effects of orthosis and kinesio-tape on anticipatory and compensatory postural adjustments.

Author	Test position	Type of perturbation (predictable/unpredictable)	Perturbation characteristics	Measurement methods (EMG)	Outcome measures (onset/amplitude of APA or CPA)
Bae et al. [54]	Sitting	Predictable (APA)	Arm raising (flexion) in response to an auditory cue	DL; TrA; OE	Onset time (difference between activation onset of DL and activation onset of the trunk muscles)
Cholewicki et al. [40]	Semi-seated	Unpredictable (CPA)	Quick force release (via a cable attached to a thoracic harness at T5 level) during isometric exertion of trunk flexion, extension, left side-bending and right rotation; Amount of resisting force: 115 N for male and 80 for female	RA, OE, OI, LD, ES thoracic, ES lumbar	Onset time; number of muscles switching – on and switching – off
Lavender et al. [41]	Standing	Unpredictable (CPA)	Sudden symmetric and asymmetric pre-loading and loading (via a container held in the hands); Amount of applied load: 7.5% maximum voluntary trunk extensor strength (isokinetic); Direction of applied load: mid-sagittal plane (symmetric) or 25 cm shifted laterally from mid-sagittal plane (asymmetric); EC	LD; ES; OE; RA	Peak EMG amplitude
Samani et al. [37]	Standing	Predictable (APA) and unpredictable (CPA)	Perturbation applied to the pelvis by releasing a pendulum; amount of load: 20% subject’s BMI; EO (APA); EC (CPA)	RA; OE; OI; TrA; ES lumbar	Amplitude and onset time (difference between contact of pendulum with subject’s body and activation onset of trunk muscles)
Voglar and Sarabon [42]	Standing	Predictable (APA) and unpredictable (CPA) perturbations	APA: Fast bilateral shoulder flexion (to raise a 0.3 kg bar) in response to an auditory cue CPA: Sudden loading; amount of load: 7 kg for male and 4 kg for female	DL; MF; ES lumbar; RA; OE; OI	Onset time (APA: difference between activation onset of DL and activation onset of the trunk muscles; CPA: delay from force release to trunk muscle activation)

APA: anticipatory postural adjustment; CPA: compensatory postural adjustment; BMI: body mass index; DL: deltoid; ES: erector spinae; OE: obliquus externus; RA: rectus abdominis; TrA: transverse abdominis; MF: multifidus; OI: obliquus internus; LD: latissimus dorsi.

Two studies evaluated the effect of orthoses using CPA paradigms [40,41], one study examined the effect of kinesio-tape using only an APAs paradigm [54], and two studies investigated the effect of orthoses [37] or kinesio-tape [42] using both APAs and CPAs paradigms. To assess APAs, expected perturbation was exerted by fast arm raising in sitting [54] or standing position [42] or by releasing a swinging pendulum in a standing position [37]. To assess CPA, unexpected perturbation was administered by applying a sudden loading into the subject's hand [41,42] or by impacting of a swinging pendulum to the pelvis while standing [37] or by a sudden force release in flexion, extension, and lateral bending through a cable connected to the thoracic region during the semi-seated position [40].

Difference between pre-test/intervention and post-test/intervention: APAs

The longer-term effects of orthosis in response to predictable perturbation in LBP patients were investigated in four muscles. All these belonged to one study [37], in which a semi-rigid LSO was prescribed in two different pressure levels (normal- and high-pressure). Out of eight assessments (four muscles × two orthosis conditions) per outcome, only three statistically significant benefits in favor of orthoses were observed, including a decrease in the amplitude of EMG of erector spinae (ES) muscle in the both groups of normal- and high-pressure orthosis, and earlier activation of transversus abdominis (T_rA) muscle in the normal-pressure orthosis group.

The longer-term effects of tape application on the timing of muscle activity in response to predictable perturbations (i.e., APAs) were investigated in seven muscles contributed by two studies. The significant findings included earlier activation of ES and multifidus muscles in healthy subjects in one study, and earlier activation of obliquus externus (OE) abdominis and T_rA muscles in LBP patients in another study.

Difference between pre-test/intervention and post-test/intervention: CPA

None of two studies examining the immediate or longer-term effects of orthosis on onset delays in six muscles reported significant changes. When the immediate or longer-term effects on amplitude of activity were examined in five muscles contributed by two studies, significant changes were found in a few experimental conditions. The significant findings included reduced activity of right OE and right rectus abdominis in healthy subjects in one study examining the immediate effects, and reduced activity of ES in LBP patients in another study examining the long-term effects of wearing orthosis with high pressure.

In a single study examining the longer-term effect of kinesio-tape in healthy subjects, none of five studied muscles showed significant changes.

Assessment of methodological quality

Out of 27 included studies, 11 articles received the complete score of reporting bias (Table 7). Aims (item 1) and outcomes (item 2) were clearly described by all studies. Nine studies did not describe the characteristics of participants in the experiment (item 3) and eight studies did not clearly describe the details of the administered external support (item 4). Only two studies failed to clearly describe the details of their findings (item 5). All but four studies provided an estimate of variance of their data (item 6). Eight studies did not declare actual p values for the main outcome measures (item 7).

Table 7. Methodological quality rating of included studies.

Author	Reporting bias							External validity		Internal validity					Power	Total score
	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15
Abbasi et al. [56]	1	1	1	1	1	1	0	0	0	1	1	1	0	0	1	10
Abbasi et al. [46]	1	1	1	1	1	1	1	0	0	0	1	0	0	0	0	8
Azadinia et al. [47]	1	1	1	1	1	1	1	0	0	0	1	1	0	1	0	10
Azadinia et al. [48]	1	1	1	0	1	1	1	0	0	0	1	1	0	1	1	10
Azadinia et al. [49]	1	1	1	0	1	1	1	0	0	0	1	1	0	1	1	10
Bae et al. [54]	1	1	1	1	1	1	0	0	0	0	1	1	0	0	0	8
Boucher et al. [14]	1	1	1	1	1	1	1	0	0	0	1	1	0	1	1	11
Cholewicki et al. [40]	1	1	0	0	1	1	1	0	0	0	1	1	0	1	0	8
Cholewicki et al. [38]	1	1	0	0	1	1	1	0	0	0	1	1	0	1	0	8
Cholewicki et al. [16]	1	1	0	1	1	1	0	0	0	0	1	1	0	1	0	8
Ghofrani et al. [53]	1	1	1	1	1	1	1	0	0	1	1	1	0	1	1	12
Hidalgo et al. [17]	1	1	1	1	0	0	0	0	0	0	1	1	1	1	1	9
Jassi et al. [55]	1	1	1	1	1	1	1	0	0	1	1	1	0	1	1	12
Kang et al. [52]	1	1	1	0	1	1	0	0	0	0	1	1	0	1	0	8
Lavender et al. [41]	1	1	0	1	1	0	1	0	0	0	1	1	0	1	0	8
Mathias and Rougier [45]	1	1	0	1	1	1	0	0	0	0	1	1	0	1	0	8
McNair and Heine [13]	1	1	0	0	1	1	0	0	0	0	0	1	1	1	0	7
Mi et al. [57]	1	1	1	1	1	1	1	0	0	0	1	1	0	1	1	11
Munoz et al. [43]	1	1	0	1	0	0	1	0	0	0	1	1	0	1	0	7
Munoz et al. [51]	1	1	0	1	1	1	0	0	0	0	1	1	0	1	0	8
Newcomer et al. [12]	1	1	1	1	1	1	1	0	0	0	0	1	1	1	0	10
Reeves et al. [44]	1	1	0	0	1	0	1	0	0	0	1	1	0	1	0	7
Ruggiero et al. [15]	1	1	1	0	1	1	1	0	0	0	1	1	0	0	1	9
Samani et al. [37]	1	1	1	1	1	1	1	0	0	0	1	0	0	1	1	10
Toprak Celenay and Ozer Kaya [50]	1	1	1	1	1	1	1	0	0	0	1	0	0	0	1	9
Toprak Celenay et al. [39]	1	1	1	1	1	1	1	0	0	0	1	0	0	1	1	10
Voglar and Sarabon [42]	1	1	1	1	1	1	1	0	0	0	1	1	0	1	1	11

Neither of the included studies reported the source population of the selected sample (item 8) and the representative of the sample (item 11). Therefore, all studies obtained zero score for external validity.

For internal validity, only in three studies assessors were blinded (item 10). With the exception of two studies, the rest of studies did not perform data dredging (item 11). Appropriate statistical tests (item 12) were used in all but four studies. Only three studies reported the acceptable reliability of their outcome measures (item 13). With the exception of few (n = 5), all studies reported random allocation to group and/or experimental conditions (item 14). More than half of the included studies (n = 14) failed to provide information regarding power calculation (item 15).

Discussion

The present systematic review investigated the change in sensorimotor function following immediate and longer-term application of external lumbar supports. Findings supported moderate effects of lumbosacral orthosis on specific aspects of sensorimotor control such as JPS and to a lesser extent postural stability (standing). Kinesio-tape had negligible effect on all domains of sensorimotor control. These findings will be discussed below in further detail.

JPS

Wearing orthosis was associated with immediate slight improvement of JPS for both LBP (one out of two studies [12,14]) and healthy (two out of four studies [12–14,16]) groups. Since none of studies assessed JPS using targets located at neutral-spine-posture, it is hard to attribute the positive findings to a specific type of target-matching task. However, if we assume that positions farther from neutral-spine-posture are more dependent on proprioceptive input as they are less practiced, then the role of orthotic devices in enhancing proprioceptive feedbacks play a more crucial role in non-neutral positions. Additionally, forces applied by the orthosis to the body, are likely larger in farther from neutral posture, which may enhance effect of the orthosis. However, further investigation is needed to explore posture dependency and the underlying mechanism of target-matching tasks on the relationship between lumbar supports and JPS.

Longer-term effects of orthosis on enhancement of JPS were positive for LBP (one out of two studies [12,37]) but negative for healthy subjects (two out of two studies [12,16]). One plausible explanation is that both groups may, over time, rely more on information provided by the orthosis and less on proprioception. This would work out negative for healthy individuals with normal proprioception but improve JPS in LBP patients with impaired proprioception.

The limited evidence regarding the effect of tape application on lumbar position sense showed mixed results. In terms of immediate effects of kinesio-tape, the results of the single included study [17] showed an increase of JPS error in both LBP and healthy groups. This is not consistent with the findings reported for longer-term effects by the other two included studies. They both reported no change of proprioceptive acuity either in healthy [15] or LBP subjects [56]. Even though the study of Abbasi et al. [56] outperformed other two studies in terms of studied population (LBP with impaired proprioception), taping method (star shape technique as the most effective method) and duration of intervention (72 h), there was only a tendency towards improvement of JPS following application of kinesio-tape (Figure 2). The insignificant findings could be due to limited sample size and consequently a lack of power of this specific study. Additionally, it is surprising that the direction of the non-significant effect (positive) is also opposite to the short-term effects (negative).

Postural control

Standing

No data regarding the effect of orthosis on standing postural control in healthy subjects exist when considering traditional COP measures. Only one of four studies [47,49,51,53] assessing postural control in LBP found a small positive effect following longer-term application of orthosis. The results of this study [49] showed that wearing orthosis reduced postural sway in the most difficult postural condition, i.e., standing on foam surface with EC. Indication of postural improvement following application of orthosis was also found when postural control was measured using other parameters and/or instruments. For instance, in the study of Mi et al. [57] wearing orthosis was associated with immediate decrease of postural sway when standing on foam with either EO or EC in both healthy and LBP groups. Similarly, LBP patients showed improvement of postural control when standing on a movable support surface (Biodex Balance System) following longer-term application of orthosis [52]. These findings are consistent with the results of a systematic review [59] which showed larger COP displacement in patients with LBP compared to healthy subjects during standing in more challenging conditions, such as standing on an unstable surface or with EC. Since LBP patients rely more on visual inputs [9] and ankle strategy [60] to maintain postural stability due to impaired lumbar proprioception, it makes sense that demands on lumbar proprioception increase in the absence of visual inputs or standing on an unstable surface (which disrupts afferent information from foot mechanoreceptors). In such cases, wearing orthosis may have improved the ability to detect body position by increasing tactile sensation, which in turn reduces postural sway.

When postural control was analyzed using traditional COP measures, none of the studies [39,46,55] found an effect of kinesio-tape following either immediate or longer-term application. Only the single study that measured postural control when standing on a dynamic support surface (Biodex Balance System) [50] reported improvement of postural stability following longer-term use of kinesio-tape in patients with LBP. If we assume that postural control should be improved through enhancing proprioceptive feedback, absence of a positive effect of kinesio-tape on JPS leaves no surprise to see postural control is unaffected following application of kinesio-tape.

Sitting

Among studies that evaluated the effect of orthosis on sitting postural stability using traditional COP parameters, only two out of four studies [38,43–45] reported an effect of wearing orthosis in healthy subjects. The results were contradictory, with one study [45] reporting a small amount of improvement (decrease) in postural sway as a result of immediate effect of wearing of orthosis (either neutral or lordotic orthosis) and the other one [43] finding a negative impact of wearing lordotic lumbosacral orthosis on postural stability during sitting on a highly unstable surface. This discrepancy could be attributed to the task difficulty. Whereas Mathias and Rougier [45] measured orthosis effects in a stable seated position with the feet unsupported (making correction by lower extremity possible), Munoz et al. [43] tested participants in a highly unstable position with both feet placed on a foot support (excluding correction by lower extremity). With an increased seat instability in the latter condition, larger adjustments are needed to be imposed by trunk to control balance. However, it is possible that orthosis makes it difficult for trunk to compensate this large amount of external perturbation. Given that all studies investigated only the immediate effects in healthy subjects, the longer-term effects of orthosis especially in LBP patients are unclear.

Only one study [15] evaluated longer-term effects (30 min) of kinesio-tape on sitting postural stability in healthy subjects and found a decrease in some COP velocity parameters. However, their findings could be related to a placebo effect because the same results were found in sham group. Moreover, according to the pretest/posttest design in their study, the evaluations were repeated 30 min after the tape application without controlling the order effect. Therefore, it is possible that the results have been subjected to a learning effect. Furthermore, the validity of outcome measures such as maximum velocity used in this study which are calculated based on only a single data point of the whole measurement trial is questionable [61].

APAs and CPAs

Studies investigating measures of postural adjustments reported mostly no effect of either orthosis or kinesio-tape. All studies measured the response of multiple trunk muscles to verify postural adjustments. Since the majority of studies reported no change of muscular activity in most or all muscle groups, it is possible that the rare positive effects are coincidental. However, the limited number of studies investigating APAs/CPAs makes it hard to draw firm conclusion regarding the efficacy of orthosis and kinesio-tape.

Methodological quality

The overall quality was relatively similar between studies that found an effect and those that did not find an effect, specifically determined per population (LBP and healthy) and duration of effect (immediate and longer-term). Detailed inspection of important parameters such as sample size and reliability of measures did not show a difference between the two groups of studies neither. The fact that many studies did not find an effect does not seem to be a power problem. Most non-significant results also showed almost equal bars in the figures.

Proposed mechanisms of actions

Various mechanisms have been hypothesized to explain change of JPS and postural control following use of lumbar orthosis, where the most significant effects were located. Enhanced proprioceptive acuity through stimulation of cutaneous mechanoreceptors is one of the proposed mechanisms. Previous research has noted that feedbacks from skin receptors improve various aspects of motor control including proprioception [62] and postural sway [63]. However, the skin contribution to improved JPS following application of orthosis can rapidly decrease over time. For instance, Newcomer et al. [12] found a reduction in JPS as an immediate effect of wearing orthosis in LBP patients but no change after two hours of wearing orthosis. A possible justification for these findings is the rapid adaptation of cutaneous receptors and losing their sensitivity to tactile pressure over time [64]. Furthermore, based on the findings of the study by Samani et al. [37], the JPS error decreased after 4 weeks of wearing orthosis. Given that they evaluated proprioception without wearing an orthosis, the improvement in proprioception could not be attributed to an increase in tactile sensation.

Some researchers suggest that orthoses decrease trunk muscle co-contraction and the activity of back-extensor muscles during daily activities by passively stiffening the trunk [65]. This gives rise to reducing muscular fatigue [66] which can lead to improvement of lumbar spine proprioception [67] and even postural sway [68]. External lumbar supports may also enhance sensorimotor function by increasing perception of security and confidence [69]. Alteration of brain regional activity is another proposed mechanism for improved proprioception. The change in brain activity during active lower extremity movement was examined while manipulating proprioceptive feedback by wearing a tight brace, a moderate tight sleeve and no brace/sleeve [70]. The findings showed higher level of brain activation while wearing external supports especially tight brace which provoke proprioception the most. Despite the above propositions, the exact mechanism by which external lumbar supports increase proprioception or its indirect measures, i.e., postural control, is still unclear.

Limitations

In this study, definition of proprioception was narrowed to JPS and among different measures of JPS only AE was analyzed. This was due to the limited number of studies which investigated other aspects or measures of JPS as well as an attempt to decrease the heterogeneity of outcome measures which helps to improve the interpretation of results. Despite narrowing down the outcome measures, we were still not able to perform a meta-analysis and hence could not provide a precise estimate of the total effect size.

This review also included studies that used different external lumbar supports with various materials, structures, or fittings which implies that findings should be interpreted cautiously because these factors may affect functioning of sensorimotor control. For instance, some evidence suggests that only a non-extensible (non-elastic) lumbar orthosis can increase trunk stiffness and thereby reduce trunk muscle co-contraction [71]. However, Boucher et al. [14] did not show a difference between the two types of extensible and non-extensible orthoses. It is quite possible that the pattern of sensorimotor behavior emerges as a result of interaction of lumbar orthoses with other components of the motor system. For instance, Munoz et al. [43] findings suggest that the effect of an orthosis on sitting postural stability can be neutral, positive, or negative based on the degree of seat instability and the structure of the orthosis.

Even though more positive findings have been reported for lumbosacral orthoses, no definitive conclusion can be drawn whether they deliver better outcomes than kinesio-tapes. It would be ideal if these two types of external lumbar supports were compared directly or if there was no difference in the way that studies were conducted, for example in terms of studied population, design, methods of assessment, etc.

Conclusions

Given that enhancing proprioception and its indirect measure, i.e., postural control, has been postulated as a putative mechanism of action of lumbar orthosis and kinesio-tape, there was a demand for a review to summarize all past research and deliver a clear and comprehensive overview of evidence on this topic. As the first review to synthesize evidence on the effect of external lumbar supports on sensorimotor control, our results indicate moderate effect of lumbar orthosis on neuromuscular adaptation. However, there was no substantial evidence for an effect of kinesio-tape. Future randomized clinical trials with high-quality methodology and long-term follow-up are warranted to determine the efficacy of external lumbar support in terms of sensorimotor performance.

Disclosure statement

The authors report no conflicts of interest.