Background: Low back pain is a major public health problem that affects most people at some point in life, and results in major psychosocial, economic, functional and physical consequences that can last for days and months. Most cases are undiagnosed and become chronic non-specific low back pain. Studies showed that these patients presented changes in postural control, yet the information is inconsistent, as well as the effects of Functional Taping (FT).

Objectives: The aim of this study will be to investigate the immediate and one-month follow-up effects of the use of Functional Taping to lumbar spine on pain intensity and postural control in patients with chronic nonspecific low back pain (CLBP).

Methods: This study will be a sham-controlled and randomized clinical trial. Participants: One hundred and twenty participants (18 and 50 years) both genders. Interventions: Participants will be randomly allocated to receive three possible interventions: Functional Star-shape Taping, Sham Functional Taping (both interventions during seven days) and a Minimal Intervention (MI) (one session). Main outcome measures: Primary outcomes will be pain intensity and posturography to assess balance parameters. Low back pain related disability, global perceived effect of treatment and fear avoidance beliefs will be considered as secondary outcomes. Four measurements of static posturography will be conducted: pre-intervention, immediately after application of the tape, after seven days post-intervention (after removal of the tape) and after one month follow-up period. Secondary and primary outcomes will be assessed on three occasions: pre-intervention, seven days post-intervention and after one month follow-up period. All statistical analysis will be conducted following the principles of intention to treat, and the effects of treatment will be calculated using linear mixed models.

BACKGROUND

Considering that evidence suggests that patients with CLBP have changes in postural control, we highlight the importance of conduct studies to identify treatment strategies that can influence postural control like as FT. In this way, the objective of the present study is to compare the effects of Functional Star-shape Taping (FST) vs. Sham-FT vs. MI on pain intensity and postural control (primary outcomes) in CLBP patients. The secondary outcomes will be low back pain related disability, global perceived effect of treatment and fear avoidance beliefs.

METHODS

Study design

This study will be a sham-controlled, randomized, three-arm parallel-group clinical Study participants

The sample will be composed of 120 participants (both genders) with nonspecific CLBP, who will be referred to the physiotherapy clinic of the UENP Center for Health Sciences (Paraná state, Brazil).

Allergy test

Firstly, an assessor blinded to the treatment allocation collected the baseline data and performed an allergy test on all participants. This allergy test consisted of applying a small patch of FT over the skin. Participants kept this patch on for 24 hours and will be instructed to remove the patch and call the researchers if any allergic reaction occurred. Only patients without allergic reaction to the patch test were then scheduled to undergo randomization.

Randomisation and allocation

The proposed study will follow the recommendations described in Consolidated Standards of Reporting Trials (CONSORT) statement (Moher et al., 2010). Once the patient has accepted an invitation to participate, they will give written consent before being assessed for eligibility. Firstly, one researcher will gather the clinical assessment and allergy test to exclude noneligible participants. Only patients without allergic reaction to the patch test will be scheduled to randomisation. After this initial assessment, participants will be randomly assigned following simple randomisation procedures (computerized random numbers) to 1 of 3 treatment groups (opaque sealed envelopes containing cards will be used): (1) Functional Star-shape Taping (FST), (2) Sham-FT and (3) (MI). The allocation sequence will be generated by a researcher not involved in the assessment and interventions, and one research assistant will assign participants to interventions.

Procedures

Following the allocation process, a blinded investigator will conduct clinical assessments and collect primary and secondary outcomes and psychosocial variables. In the same session, another investigator who is a certified Kinesio tape practitioner, will proceed with the treatment according to the group assignment, and will be therefore responsible for applying the functional tape and MI. Patients in the FST and Sham-FT groups will be blinded to interventions (sham or not) and will be advised to leave the tape in situ for one week. The MI group will receive a booklet with biopsychosocial education and orientations.

Initial evaluation

The evaluations will be carried out according to the recommendations of the Initiative on Methods, Measurement and Pain Assessment in Clinical Trials (IMMPACT) for chronic pain.

Primary Outcomes

Pain intensity

Measurement of pain intensity will accomplish using the application of the NPRS, which consists of a sequence of numbers from 0 to 10, in which 0 represents "no pain" and 10 represents "worst pain imaginable".

Postural control on force platform - Static Posturography with and without a secondary task

Static posturography will be evaluated using a force platform (400 Biomec, EMG system of Brazil Ltda®, São José dos Campos, Brazil), with frequency acquisition of 100 Hz and a second-order 35 Hz low pass Butterworth filter. Posturography analysis of the COP will be carried out by four main parameters of balance: (1) ellipse (95%) of the COP in square centimeters (A-COP in cm2); (2) Root Mean Square of oscillation of the COP (RMS in cm2); (3) mean speed (MVeloc in cm/s) of the displacement of the COP in anteroposterior (A/P) and medial-lateral (M/L) directions; and (4) mean frequency (MF in Hz) of the displacement of the COP in anteroposterior (A/P) and medial-lateral (M/L) directions.

A modified clinical test of sensory interaction for balance (CTSIBm) will be used by measuring the static balance in four sensory conditions: (1) eyes open on stable surface; (2) eyes closed on stable surface; (3) eyes open on unstable surface; (4) eyes closed on unstable surface. For each condition, the participant will be evaluated three times for 40 seconds with a 30-second interval between assessments.

For the assessment of static posturography with a secondary task, volunteers will be requested to perform a fast movement of shoulder flexion (bilateral). Participants will be trained to carry out the tests with maximum arm speed (approximately 120º/seg) and amplitude at about 60º immediately after the auditory stimulus. Participants will perform five movements (open and closed eyes), with a time interval of 30 seconds between each repetition and an auditory stimulus will precede the trigger by a random period of 0.5-2 s.

Secondary Outcomes

Disability and Participant ratings of global improvement and satisfaction with treatment - Global perceived effect Fear avoidance beliefs questionnaire (FABQ).

Psychosocial Measures - Baseline measure

Hospital anxiety and depression scale - HADS and Pain catastrophizing scale - PCS and Chronic Pain Self-Efficacy Scale - CPSS.

Interventions

Functional Taping Intervention

Participants will be subjected to one of two possible intervention procedures with FT: 1) Functional Star-shape Taping (FST); 2) Sham Functional Taping (Sham-FT). The participants will be blinded as to whether they received SFT, or Sham-FT, and the two interventions will be performed in the lumbar region. The elastic adhesive bandage used will have 5.0 cm wide and 0.5 mm thick (Kinesio Tex Gold® brand, Kinesio Holding Corporation, Albuquerque, USA) and resistant to contact with water. All participants will be informed that they would receive one of the two types of FT application. During this period of application, the participants will be directed to maintain their daily life activities, and will be blinded with respect to which intervention procedure they received (if sham or not).

Minimal Intervention Strategy (MI)

The MI group will receive an educational and counseling booklet (a booklet based on The Back Book).

Data analysis

The two primary outcome variables (posturography and pain intensity) were considered for calculation of sample size. For posturography, we will consider an improvement of at least 20% mean speed of oscillation of the COP pre- and immediate post-treatment. The sample size was 27 participants. The following specifications were considered: α=5% and 95% statistical power and effect size of 0.76 for F-test. For pain intensity, an improvement of at least 20% on the NPRS (pre-treatment: 5.6 and post-treatment and follow-up: 4, SD = 1.8). The sample size obtained was 93 (31 participants per group). The following specifications were considered: α=5% and statistical power of 95% and effect size of 0.41 for F-test. Thus, to ensure a power suitable and assuming sample losses, 120 participants will be considered (at least #9 losses per group) (GPower 3.0.10, University of Kiel, Germany).

The statistician will be given grouped data, but data will be coded so that the statistician will remain blinded to patients' group allocation and to protect patient confidentiality. The mean effects of the interventions and the group differences for all outcomes (primary and secondary) will be calculated using linear mixed models that incorporated terms for the treatment groups, time (post-intervention and follow-up), and interaction terms (treatment subgroups and time) as well as psychosocial variables, sex and age as covariates. Secondary analysis will be conducted using regression models to determine whether baseline scores of psychosocial variables (HADS, PCS, CPSS) will moderate the effect of treatments (FT, sham FT or MI). The analyzes will follow the intention-to-treat principles.

Additionally, analyzes will be performed on subgroups of patients with worse and better postural control parameters by determining cut-off values for instability based on data previously published in the literature. These analyzes will be carried out to identify potential subgroups of better and worse rates of postural control and possible effects of FT. The same procedure will be performed to analyze psychosocial subgroups.

For all of these analyzes, we will use the IBM SPSS software package, version 22 (IBM Corp, Armonk, New York).

Inclusion Criteria:

• (1) aged between 18 and 50 years;
• (2) medical diagnosis of chronic non-specific low back pain in the last 3 months and/or pain during at least half of the days in the past 6 months (Deyo et al. 2014), that is located between T12 and the gluteal folds;
• (3) pain intensity equal to or greater than three;
• (4) pain caused by certain postures, activities and movements; and
• (5) score greater than 14% on the Oswestry Lumbar Disability Index (Vibe Fersum et al. 2013).

Exclusion Criteria:

• (1) red flags (neoplastic diseases or tumors in the spine, inflammatory diseases, infections and fractures);
• (2) serious neurological (or central and peripheral neurological) symptoms, psychiatric, rheumatologic and cardiac diseases;
• (3) disc herniation;
• (4) lumbar stenosis;
• (5) spondylolisthesis;
• (6) history of spinal surgeries;
• (7) pregnancy;
• (8) menstrual period;
• (9) underwent physical therapy treatments (less than 6 months before the evaluation period);
• (10) participants with previously diagnosed balance disorders or with disorders that may interfere with balance (vestibular diseases, whiplash injuries, functional ankle instability or report of "giving" way sensation in ankle during the past 6 months); and
• (11) using medications that alter or cause suppression of sensory perception.