Available in Chile
1.1 Study Type and Design: Experimental design for a non-controlled clinical trial.The
study will be conducted in the Electrophysical Agents Laboratory (KIN 401) at the School
of Physical Therapy, Faculty of Rehabilitation Sciences, Casona de las Condes Campus,
Universidad Andrés Bello, located at Calle Fernández Concha Nº700, Las Condes, Santiago,
Chile. The sample will be selected from the university population of the same faculty.
The study group will be determined through a non-probabilistic sampling process.
Participants will be recruited via a closed-ended questionnaire constructed according to
selection criteria. The minimum number of participants required for the study will be
calculated using the G-Power program, with a minimum of 20 participants. Subjects with
CNNP pain will be recruited and will receive 8 sessions of HILT and stretching exercises
over 4 weeks. Relevant outcomes will include resting pain intensity (RPI), movement pain
intensity (MPI), and pressure pain threshold (PPT). Additionally, cervical range of
motion (CROM) and neck disability (ND) will be assessed. Evaluations will be conducted at
three time points: before treatment, at the end of treatment, and at a one-month
follow-up evaluation.
1.2 Overall Objective To evaluate the effect of high-intensity laser therapy on reducing
pain, increasing pain pressure threshold, improving cervical range of motion, and
decreasing cervical disability in patients with non-specific chronic neck pain.
1.3 Specific Objectives - Determine the difference in cervical pain intensity before and
after high-intensity laser therapy treatment.
- Assess the change in cervical pain pressure threshold before and after treatment
with high-intensity laser therapy.
- Measure improvement in cervical range of motion in terms of flexion, extension,
rotation, and lateral bending following high-intensity laser therapy.
- Evaluate the reduction in cervical disability using the cervical disability index
before and after treatment with high-intensity laser therapy.
- Investigate the correlation between pain reduction, pain pressure threshold,
improvement in range of motion, and reduction in cervical disability in response to
high-intensity laser therapy.
1.4 Phases of the clinical trial
- Study Preparation and Design: In this initial stage, the experimental design of the
non-controlled clinical trial will be established, defining study objectives and
selecting key variables for measurement. Additionally, the laboratory environment
will be prepared, and the research protocol will be designed.
- Treatment Implementation and Execution: During this phase, the study will be
implemented, involving sample selection through a non-probabilistic sampling
process, administration of the treatment (HILT and stretching exercises) to
recruited participants, and collection of relevant clinical data.
- Evaluation and Results Analysis: The final stage will focus on evaluating the
obtained results, including measurement of variables such as pain intensity, pain
pressure threshold, cervical range of motion, and cervical disability. Statistical
analyses will be conducted to determine treatment efficacy, and conclusions will be
drawn based on the study findings.
2.1 Conceptual Definition of Variables:
- Pain intensity at rest: discomfort or more intense forms of pain localized in the
cervical region, lateral neck, shoulders, or scapular region, reported by
participants while at rest.
- Pain intensity at movement: discomfort or more intense forms of pain localized in
the cervical region, lateral neck, shoulders, or scapular region, manifested by
participants during neck movements.
- Pain pressure threshold: the minimum amount of pressure applied to a specific area
of the body that induces the sensation of pain.
- Cervical range of motion: capacity of movement in the cervical spine, including
movements in various anatomical planes such as flexion, extension, lateral bending,
and rotation.
- Neck disability: limitation or restriction in neck functional capacity, manifested
as difficulty in performing daily activities such as neck movement, maintaining an
upright posture, performing work tasks, or engaging in recreational activities.
- Stretching exercises: static passive stretching exercises performed bilaterally by
the therapist on the upper trapezius, levator scapulae, and scalene muscles, each
held for 30 seconds with 30-second intervals, totaling 3 sets for each muscle group.
- High-intensity laser therapy uses concentrated laser light with power greater than
0.5 watts to treat musculoskeletal injuries, chronic pain, and promote healing
through thermal effects and photobiomodulation.
2.2 Operational Definition of Variables: - Pain intensity at rest: assessed using the
Numeric Pain Rating Scale (NPRS) from Gymna (R). measured on a scale from 0 to 10, where
0 represents no pain and 10 represents the most pain the participant reported.
- Pain intensity at movement: assessed using the Numeric Pain Rating Scale (NPRS) from
Gymna (R). measured on a scale from 0 to 10, where 0 represents no pain and 10
represents the most pain the participant reported.
- Pain pressure threshold: assessed using pressure algometry with the FPX Wagner
pressure algometer (R). The pressure threshold will be measured in pounds per square
centimeter (lb/cm2).
- Cervical range of motion: assessed using inclinometry with the CROM device. The
range of motion will be quantified in degrees (°).
- Neck disability is assessed using the Neck Disability Index (NDI). Cervical
disability will be expressed as a percentage, where 0% indicates no disability and
100% indicates maximum disability.
- Stretching exercises: static and passive stretching exercises performed bilaterally
by the therapist on the upper trapezius, levator scapulae, and scalene muscles. Each
exercise will be held for 30 seconds with 30-second intervals, and 3 sets will be
performed for each muscle group.
- High-intensity laser: application of a high-power laser using the BTL-6000 device at
12 Watts.
2.3 Types of Variables:
- Pain intensity at rest: dependent variable, ordinal qualitative.
- Pain intensity at movement: dependent variable, ordinal qualitative.
- Pain pressure threshold: dependent variable, continuous quantitative.
- Cervical range of motion: dependent variable, continuous quantitative.
- Neck disability: dependent variable, continuous quantitative.
- Cervical stretching exercises: independent variable, nominal qualitative.
- High-intensity laser therapy: independent variable, continuous quantitative.
3. Ethical Considerations: The study received approval from the Ethics Committee
of the Metropolitan East Health Service of Santiago, Chile, on October 26,
2022, in accordance with the principles of the Declaration of Helsinki
(approval number 20200234).
4. Participants: Participants will be recruited from the community of Universidad
Andrés Bello. The study will be advertised through official channels, including
email distribution and publication on the institutional website. Additionally,
communication channels such as emails, social media, and panels within the
Physical Therapy Department will be utilized. Volunteers will be contacted via
telephone or email to attend the Electrophysical Agents Laboratory at the
Faculty of Rehabilitation Sciences.
5. Sample size: The sample size will be determined using G-Power software,
considering a power of 90% (1-β), a confidence level of 95%, a significance
level of 5% (α), and an effect size of 0.6. Previous studies in individuals
with CNP have shown differences in pain intensity, favoring HILT plus exercise
over ultrasound plus exercise. Therefore, a minimum sample size of 17
participants will be established. To accommodate potential dropouts during the
study or follow-up, an additional 15% will be added to the sample, resulting in
a total of at least 20 participants.
6. Intervention: Participants will form a study group receiving HILT as an
intervention. Alongside laser therapy, they will undergo a regimen of passive
bilateral static stretching exercises targeting the upper trapezius, levator
scapulae, and scalene muscles, with each stretch held for 30 seconds per set.
These stretching exercises will be conducted immediately following the HILT
treatment. The interventions will take place twice weekly over a span of four
weeks, totaling eight sessions. These interventions will occur twice a week for
four weeks, totaling eight sessions. Each treatment will be administered by an
independent therapist ensuring intervention blindness.
- High-intensity laser therapy. For laser therapy, the BTL-6000 device with 12W power
and a wavelength of 1,064 nm will be used. The treatment protocol integrates manual
scanning and point techniques following De la Barra et al. It consists of three
phases: Phase 1, manual scanning with 12 W power for 42 seconds per upper trapezius
muscle, delivering 1,000 J in total; Phase 2, point technique (static) using 4 W
power for 10 seconds per point, delivering 120 J in total; Phase 3, manual scanning
with 6 W power for 83 seconds per upper trapezius muscle, delivering 1,000 J in
total.
- Stretching exercise. Participants will also undergo passive bilateral static
stretching exercises targeting the upper trapezius, levator scapulae, and scalene
muscles. A therapist will administer these exercises, lasting 30 seconds each with a
30-second rest between sets, following the HILT treatment.
7. Outcomes of Interest: The primary outcome measures will include resting pain
intensity (RPI), pain intensity during movement (MPI), both assessed using the
Numerical Pain Rating Scale (NPRS), and pain pressure threshold (PPT),
evaluated with algometry. Algometry will assess six bilateral points across the
cervical region, shoulders, and interscapular region. Secondary outcomes will
encompass cervical range of motion (CROM), evaluated using inclinometry, and
cervical disability, assessed with the Neck Disability Index (NDI). Evaluations
will occur at three time points: baseline (before treatment), immediately
post-treatment, and four weeks post-treatment (follow-up assessment). Two
independent evaluators will conduct the assessments to ensure blindness in the
evaluation process: one will handle the algometry assessment and NPRS
application, while the other will handle the CROM evaluation. Neck disability
will be assessed using the self-administered NDI questionnaire.
8. Statistical Analysis: Descriptive statistics such as means, standard
deviations, medians, and interquartile ranges will be used to analyze the
variables RPI, MPI, PPT, CROM, and ND, based on data distribution. Tables will
be created with demographic data such as gender and body mass index. For
inferential analysis, tests for normality and homoscedasticity, such as the
Shapiro-Wilk test and Bartlett's test, respectively, will be employed.
Depending on the results, parametric or non-parametric tests will be selected:
a one-way ANOVA or Kruskal-Wallis test to evaluate differences between
sessions. Post-hoc analyses will be conducted using Tukey's or Bonferroni's
tests for multiple comparisons. The significance level will be set at 0.05, and
data analysis will be performed using IBM Statistical Package for the Social
Sciences (SPSS) software (version 26; SPSS Inc.; Chicago, IL).
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