The Effect of Combining Spinal Manipulation and Dry Needling in Individuals With Non-specific Low Back
Phase: NA
Conditions: Non-specific Low Back Pain
Sponsor: University of Utah

 
 
 
The Eﬀect of Combining Spinal Manipula7on and Dry Needling in  
Individuals with Non-speciﬁc Low Back Pain 
 
 
 
Study Protocol and Sta7s7cal Analysis Plan 
 
Approved un7l 12/10/2023 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

This study will use a randomized comparative design with three intervention 
groups in individuals with nonspecific LBP. The first patient-reported outcome to be 
assessed is disability, assessed with the LBP Oswestry Disability Index Questionnaire 
(ODI). The ODI score is derived from the Oswestry Disability Questionnaire, resulting in 
a score ranging from 0-100 with higher numbers indicating a greater level of disability 
[84]. Patient-centered outcome measures represent the majority of clinical 
nonmechanistic measures from the view and disability outlook of the patient. They are 
an effective way for the patient to explain the degree of pain and disability being 
experienced from LBP.  
The second patient-reported outcome will utilize the pain rating score derived 
from the numeric pain rating scale (NPRS) to evaluate pain intensity throughout the trial. 
Participants will be asked to make separate ratings of current pain intensity and the best 
and worst intensity over the past 24 hours on a 0-10 scale (“0” no pain and “10” worst 
imaginable pain). The mean of the three ratings will be used to represent pain intensity.  
The mechanistic outcome measures include LMM, ES, and GM muscle activation 
measured by changes in contraction thickness at rest and sub-maximal isometric 
contraction. The primary comparison will consist of the combination group compared 
against each single treatment group of SMT or DN in order to evaluate the advantage of 
utilizing both modalities together. This study will further perform a secondary exploratory 
comparison of the SMT and DN only groups. The primary comparison time-point will 
evaluate these outcome measures at 4-weeks (late effect) compared to baseline and a 
secondary comparison (early effect) at 2-weeks with comparison being controlled for 
baseline value. A third comparison time-point will be evaluated at 1-week consisting of 

only patient-reported outcomes to assess initial effects of treatment on reported pain. All 
patient-reported outcomes will be assessed 48 hours following the second and fourth 
treatment sessions. The duration of the trial intervention for a participant will be four 
weeks from initial baseline assessment. Participants will be randomly assigned to one of 
three intervention groups for the first 2 weeks of treatment: combination of SMT and 
DN, DN only, and SMT only. Each treatment group will receive two treatment sessions 
per week for the first two weeks with NPRS and ODI measures assessed at baseline, 1-
week, and 2-weeks. The third and fourth weeks will consist of an at home exercise 
program with NPRS and ODI measures taken at the final assessment at the end of the 
fourth week. Diagnostic ultrasound measures of the LMM, ES, and GM muscles will be 
taken at baseline and post-treatment following the fourth and final assessment 
sessions.  
 
Randomization and data collection 
Randomization will be conducted utilizing REDCap in order to conceal sequence 
from participants and researchers. Participants will be randomized into one of three 
treatment groups. The use of standard protocols and compliance audits throughout the 
study will be utilized to minimize potential bias. Study data will be collected and 
managed using REDCap electronic data capture tools hosted at the University of Utah.  
 
Outcome measures 
After attaining informed consent, participants will complete a baseline 
assessment. Participant demographics, age, gender, race/ethnicity, body mass index, 
marital status, employment status, highest education level, current and past LBP 

interventions, and a physical examination will be collected and performed. The physical 
examination will include various tests designed to ensure proper study inclusion and to 
identify the most symptomatic side (right or left) and most symptomatic levels (L3, L4, or 
L5) for treatment and outcome assessment.  
LMM, ES, and GM muscle activation will be measured with brightness-mode 
ultrasound images using a Sonosite MicroMaxx (Sonosite Inc. Bothell, WA, USA) and a 
60-mm, 2–5 MHz curvilinear array or a Butterfly iQ+ (2020 Butterfly Network Inc., 
Burlington, Massachusetts) with both using a validated protocol. Measures for the LM 
will be taken with the participant in the prone position. The ultrasound transducer will be 
placed just lateral to the spinal midline and angled medially until a parasagittal view of 
the multifidus muscle is obtained. Images will be obtained at the most symptomatic side 
and level with the muscles at rest and during submaximal contraction in response to the 
participant raising the contralateral arm about two inches while holding a weight 
proportional to body weight, resulting in approximately 30% maximum voluntary 
isometric LMM contraction. Measurements at rest and contracted will be taken three 
times at the treatment sites. Offline measures of the multifidus muscle activation will be 
obtained for both the resting and contracted states from determining the distance 
between the posterior-most aspect of the facet joint inferiorly and the plane between the 
multifidus and throacolumbar fascia superior. Images of the GM muscle will be obtained 
with the transducer positioned midway between the posterior iliac spine (PSIS) and the 
greater trochanter. Thickness measurements will be taken between the ischium and the 
fascial plane between the GM and gluteus maximus muscles along the mid-axillary line 
and the middle of the muscle belly centered within the field of view. The ES muscle will 

be imaged following techniques used with the transducer positioned on the bulk of the 
muscle immediately above the iliac crest centered on the symptomatic side and spinal 
level. The transducer will be oriented in the sagittal plane so that it is roughly parallel to 
the muscle fibers and angled slightly medially to optimize image clarity. Muscle 
activation will be calculated as the change in thickness at rest and submaximal 
contraction (Thicknesscontracted-Thicknessrest) /(Thicknessrest). The average of the 
three measures will be calculated at each treated symptomatic spinal level. All muscle 
thickness measures will be downloaded and performed offline on a different date from 
when the images are obtained utilizing Image J software (V1.38t, National Institutes of 
Health, Bethesda, Maryland) [85]. The researcher performing the offline muscle 
thickness measures will be blinded to participant treatment group allocation and 
measurement timepoint in order to control for any potential measurement bias.  
 
Intervention groups 
This study will involve three intervention components provided in different 
sequences and combinations for four weeks. Following baseline assessment, each 
study participant will be randomized to a treatment group to receive SMT, DN, or a 
combination of DN and SMT. Each treatment session will begin with a brief assessment 
by the clinician to assure the participant has remained appropriate to receive treatment.  
All SMT treatment sessions will be provided using protocols applied in previous 
studies investigating clinical outcomes and mechanism of effect. The preferred SMT 
technique will be performed with the participant supine. The clinician will stand opposite 
the side to be manipulated and side-bend the participant. The side to be manipulated 
will be the side identified as more painful. The participant will then interlock their fingers 

behind the head. The clinician will then rotate the participant and deliver a high-velocity, 
low-amplitude (HVLA) thrust to the anterior superior iliac spine with a posterior/inferior 
direction. The clinician will note if a cavitation (i.e. a “pop”) occurs and record which 
attempt and side that it occurred. Each participant receiving SMT will have two attempts 
per side performed regardless of when a cavitation occurred. If no cavitation occurs on 
any attempt this will also be noted. The substitution of the supine position for the side-
lying technique will be permitted based on participant preference or comfort. Once 
participant preference is determined at the baseline examination the chosen technique 
will be used for the duration of the trial for that respective participant.  
DN treatment will be performed in the ES, GM, and LM at the most symptomatic 
side and spinal levels determined at baseline examination. If the clinician is unable to 
determine the most symptomatic levels or areas, treatment will be performed to the 
middle of the ES and LM bellies at the L4 and L5 levels and the ipsilateral GM. General 
needle technique utilized for all muscles will include insertion of a sterile, disposable, 
solid filament steel needle (Seirin Corp., Shizuoka, Japan) into the desired muscle. The 
size of the needle will be either 0.25 x 50mm or 0.30 x 60mm based on the size of the 
participant. “Clean needle technique” will be used throughout the treatment procedures 
which included hand washing, clean latex-free nitrile exam gloves, and cleaning the 
participants skin with an alcohol swab prior to treatment. The needle technique that will 
be utilized for the LM is to start at approximately 1.5 cm lateral to the spinous process 
angling approximately 15-20 degrees medially and slightly inferior inserting the needle 
into the depth of the muscle until the lumbar lamina was reached. For the ES muscles, 
the needle will be inserted just lateral to the paraspinal muscle bulk (approximately 5-10 

cm lateral to the spinous process) in the lateral to medial direction towards the spinous 
process. The GM will be needled in the upper lateral quadrant of the buttock between 
the region proximal to the greater trochanter and inferior to the iliac crest. The needles 
will remain in the muscle for 10 minutes with needle manipulations being delivered 
every 2 minutes to elicit a local twitch response.  
Exercise sessions will consist of a series of LM exercises targeting isometric 
muscle contraction and activation. Specific exercises were selected that not only 
activated the LM, but also the GM and ES muscles. Following the fourth treatment 
session, the participant will be assigned a home exercise program consisting of 
isometric multifidus contractions in different positions with initial clinician feedback and 
exercises to isometrically co-contract the multifidus and deep abdominal muscles. 
Participants will also perform lumbar extensor strengthening exercises shown to 
produce 20-50% multifidus maximum voluntary contraction. Participants will continue to 
perform the assigned exercises through the third and fourth weeks at home up until the 
final assessment. The prescribed exercises and participant compliance with assigned 
exercises will be recorded at the final assessment session.  
There is little to no research on which therapy should precede the other in the 
combination SMT and DN group, and instead of leaving it up to clinician preference and 
to maintain consistency in treatment, SMT was designated to be performed first with DN 
following manipulation therapy. Following the two-week intervention period of SMT and 
DN, DN, or SMT the participants will begin the second phase of treatment consisting of 
two weeks of at home activation/strengthening exercises for two weeks.  
 
Statistical methods 

The study treatments will include spinal manipulation therapy (SMT), dry 
needling (DN), and exercise (EXER). Participants will be block randomized in sizes of 3 
and 6 into three study groups: (SMT+EXER), (DN+EXER), and (SMT+DN+EXER). 
Repeated measurements of the outcomes will be collected at baseline, two weeks post-
treatment, and four weeks post-treatment. The first primary outcome is the continuous 
variable Oswestry Disability Index (ODI). The second primary outcome is the continuous 
variable 0-10 numeric pain rating scale (NPRS). The primary time point is at four weeks 
(late effect) and the secondary time point is at two weeks (early effect). To determine if 
(SMT+DN+EXER) is superior to (SMT+EXER) on the ODI outcome, a linear regression 
model will be fitted using the 2-week ODI as the outcome variable, group as the primary 
predictor [(SMT+DN+EXER) vs (SMT+EXER)], and baseline ODI as a covariate, in an 
analysis of covariance (ANCOVA) fashion. In a similar model, (SMT+DN+EXER) will be 
compared to (DN+EXER). All comparisons will be made at the alpha 0.05 level.   
Exercise compliance will be measured by participants self-reporting adherence to 
the program by selecting average number of days per week the exercises were 
completed. Self-reporting will take place during the final visit at the end of the fourth 
week. Participants will be informed of this method of self-reporting compliance in order 
to aid in tracking adherence over the two-week period. 
 
Sample size justification 
For a simple comparison of a post (week 2) standardized (z-score) outcome 
variable, which is the standardized outcome variable in the ANCOVA model, mean +/- 
SD: 0 +/- 1 versus 0.64 +/- 1 (that is, a 0.64 SD difference), we required n= 41 per group 
to achieve 80% power using a two-sided alpha 0.05 comparison. We assumed a 

correlation of r = .50 between the baseline and post-treatment outcomes, which was a 
reasonable assumption given that changes over two weeks would mostly be in the 
improvement direction, with minimal patients changing in the opposite direction. The 
n=40 per group sample size was next adjusted to account for the increased power 
achieved by the ANCOVA approach [180]. In doing this, the n = 40 was multiplied by the 
factor (1 – r2) = (1-0.502) = 0.75, so we only required n = 40 × .75 = 30 per group to 
achieve the same effect size. Based on prior work of 92% retention to a four-week trial, 
a sample size of n=99, 33 per group, accounts for potential participant drop-out 
[20,168]. This planned sample size works if a 0.64 SD difference is likely or represents 
at least a minimal clinically meaning difference. In a DN study, baseline ODI was mean 
+/- SD 31.5 +/- 11.5 which decreased to 23.4 +/- 13.5 one-week post-treatment, a mean 
difference divided by pooled SD, while assuming r=0.50, of (23.4 - 31.5)/12.6 = -0.64 
SD difference. In the same study, although a difference in NPRS was not reported, 
baseline NPRS mean +/- SD was 5.0 +/- 1.7. A 0.64 SD improvement would be (5.0/1.7) 
x 0.64 =1.9 point change. This reduction in pain would be noticeable and beneficial to 
the patient, and so is at least a minimally, clinically relevant effect size [181]. In a SMT 
study [51,182], reported baseline ODI mean +/- SD 32.2 +/- 11.9 which decreased to 
23.9±11.4 post-treatment, a (23.9-32.2)/11.7 = -0.71 SD difference. So, both DN and 
SMT achieve a 0.64 SD effect size by themselves. However, our study specifically 
tested if DN+SMT is superior to DN and is superior to SMT. Individual participant 
response to only DN or only SMT could vary, with some level of synergy of DN+SMT 
being more effective than the sum of the individual effects. Therefore, we used the 0.64 

SD effect size for this test as our minimally clinically relevant effect, consistent with the 
individual treatment effects.