Comparing manual and mechanically assisted manipulations of the thoracic spine in neck pain patients : A pilot study

Manipulations of the thoracic spine are a common treatment Background: option in patients with neck pain. This approach avoids the risk of cervical arterial dissection. Currently there are different options available which have been evaluated for their efficacy. The aim of this study was to assess shortand long-term effects of two different methods of manipulating the thoracic spine in combination with a standardized exercise program for neck pain. This pilot study included patients who were over 18 years of age, Methods: able to speak and read German or English, had acute or chronic neck pain, and had not previously undergone manual therapy for the thoracic spine. Patients were recruited from private physical therapy practices. Patients were randomly assigned to two treatment groups by using block randomization. The objective was to compare the effects of manually performed manipulations and electromechanical manipulations on the thoracic spine in patients with neck pain. Primary outcome was the visual analogue pain rating scale. Secondary outcomes included Neck Disability Index, European Quality of Life scale, and Patients’ Global Impression of Change Scale. Ten patients were recruited. Five patients received manual Results: manipulations, and five received electromechanical manipulations. Both groups showed an improvement in pain scores (VAS) (X (5) = 14.161, p = 0.015) with no difference between the groups. There were no significant changes in the secondary outcomes. The electromechanical (Impulse iQ®) manipulations group showed a clinically relevant reduction in the neck disability index. Both manual and electromechanical manipulations are well Conclusion: tolerated, and show that they can be both successful treatments for neck pain in combination with exercises. Thoracic manipulations seem to be beneficial for the patient’s complaint of neck pain, while electromechanical manipulations seem to be able to reduce neck disability. Current Controlled Trials ISRCTN88585962, registered in Trial registration: January 2013. 1,2 2 1

Manipulations may be delivered either manually (high velocity low amplitude) or mechanically using different spring-loaded or electromechanical devices [24][25][26][27] .However, manual forces given by the same practitioner may vary somewhat for each manipulation session and between practitioners 28 .Forces applied by an electromechanical device are more consistent 24 .Thus far, only three studies have compared between manual and mechanical manipulations 26,27,29  The objective of our pilot study was to compare short-and long-term effects of two different ways of manipulating the thoracic spine in combination with a standardized exercise program for neck pain.

Study design
A pilot study was conducted to compare the effects of two different methods of manipulation (manual manipulation vs. electromechanical manipulation) on the thoracic spine for patients with neck pain.A complete study protocol for a randomized Additional evaluations (history taking and physical examination) of the participant were added after baseline measurements to confirm eligibility of the participant to be included in the study population 30 .

Randomization
A clinician not involved in the study randomized the participants independently into one of the two groups.Block randomization (20 blocks of 4) was carried out using a computer-based randomization program.The original list was stored in an opaque and sealed envelope, not accessible to the therapist delivering the manipulations.To reduce intervention bias, 80 individually numbered opaque and sealed envelopes were prepared, and the therapist received the assigned envelope immediately before each participant was to receive the manipulation.Additionally, after the participants completed the questionnaires, they were put into an opaque envelope that was individually and immediately sealed by the patient.The therapist was unaware of the outcome.The anonymous data were entered into the database and were untraceable to the participating patient.

Intervention
Each patient underwent three treatment sessions, with 4 days interval between each session.Additionally, during the first session, all participants were instructed to participate in an exercise program, which was to be completed as soon as possible.To evaluate compliance of the participants, they received a journal and were asked to mark the days that they had completed the required exercises.Follow-up assessments were conducted at 6 weeks, 3 months, and 6 months after the initial treatment.
Patients received the questionnaires by mail, including prepaid envelopes, to facilitate return of the completed forms.An extensive explanation of the treatments can be found elsewhere 30 .

Manual manipulations
For the manually performed manipulations, the patient was supine.The therapist's hand was placed under the thoracic spine using a pistol grip (the fingers positioned with the index finger straightened and fingers 3 to 5 flexed).The patient's forearms were crossed in front of their chest.The force was applied against the therapist's flexed fingers and the thenar eminence and slightly cranial to the transverse process of the caudal vertebrae of the segment to be treated 32 .

Electromechanical manipulations
For the electromechanical manipulations, the Impulse iQ® (Neuromechanical Innovations, Chandler, AZ, USA) was used.
The patient was prone on a treatment table, with arms parallel to the body, in a relaxed position.Before the treatment began, the patient was instructed that they would hear a rattling sound that indicated the treatment thrusts conducted by the device and a beep to signify the end of treatment.The Impulse iQ was placed onto the vertebrae previously identified as the painful segment.A double stylus and middle force setting (peak force = 200 N), as recommended by the manufacturer for the treatment of the thoracic spine, was used 33 .The device recorded and analyzed the spinal acceleration response each time a thrust was delivered by using the in-built firmware.To begin, the machine produced a series of repetitive thrusts while monitoring the acceleration response.If the response improved, the treatment thrusts continued up to 3 more seconds.If the acceleration response was negative (flat line or decrease), the thrusts delivered by the instrument ceased.

Exercise program
After the first treatment session, all patients were introduced to the home exercise program and asked to perform this program once a day for 6 weeks.Compliance with the home exercise program was assessed using a training journal as follows: (1) retraining the craniocervical muscles (e.g., training the holding capacity of the deep neck flexors and head lift), (2) retraining the scapular muscles, and (3) eye/head coordination 34,35 .For a complete overview of the study`s course see Figure 1.

Outcome measures
Baseline measures included age, weight, height, and the European Quality of Life 5 Dimensions 5 Levels (EQ-5D-5L).Furthermore, each patient's expectation of treatment outcome (the treatment he or she expected to be more beneficial) was assessed at the beginning of the study.The primary outcome measure was the Visual Analogue Pain rating scale (VAS) that assesses pain intensity level [36][37][38][39] .The VAS was completed before and after every treatment session and at all follow-up points.Secondary outcomes were the Neck Disability Index (NDI) and the Patients Global Impression of Change Scale (PGIC) [40][41][42][43][44] .
The NDI is a self-reported questionnaire to evaluate disability.It consists of 10 items that score from zero to five.The higher the total score, the higher is the disability level of the patient 41 .The NDI's minimal clinical important difference (MCID) in patients with neck pain ranges from 3.5 to 9.5, which mainly depends on the patient characteristics [45][46][47] .Pereira et al. (2015) state that in patients with chronic neck pain, the score has to be above 5.5 points, otherwise it is clinically irrelevant 45,48,49 .Before the second, third treatments and all follow-up assessment, the patients were asked about their global impression of change, using the PGIC 50 .The PGIC is a valid outcome measure that is based on a seven-point Likert scale 51 .Its purpose is to obtain a patient's report of improvement over time during treatment.The scale ranges from much better, better, somewhat better, no change, somewhat worse, worse, and much worse.Much better is rated as 7 and much worse as 1 44 .It can be used to dichotomize participants into two groups: improved (ratings of 6 and 7) and not improved (ratings 1 to 5).

Statistics
The data were stored and analyzed using the IBM SPSS 21 statistical software package (SPSS, Inc., Chicago, IL).Descriptive statistics were used to describe patient characteristics.Collected data were checked for normal distribution using the Shapiro-Wilk Test.The test identified that the scores for VAS and NDI were normally distributed.Because of outliers, the Friedman test was used as a nonparametric statistical test to retain all data points.The goal was to determine whether there were any statistically significant differences between the distributions of three or more related groups.Furthermore, pairwise comparisons were performed (SPSS Statistics, 2012) with a Bonferroni correction for multiple comparisons.

Results
The study included two male and eight female participants.Because of unknown causes, one participant dropped out of the study after the first treatment.Nine participants had experienced chronic neck pain problems (>90 days), and one patient had acute problems (<90 days) (please see Table 4).Two participants had co-morbidities such as low back pain and coccydynia.Six participants believed that the conventional (manual) manipulation would be more successful, while four believed the electromechanical manipulation would be superior.Five participants received a manual treatment, and the remaining five received an electromechanical treatment.Three participants identified the third thoracic vertebra as the most painful and two identified the seventh thoracic vertebra.The second, fourth, fifth, sixth, and the tenth thoracic vertebrae were named by one patient as the most painful ones.Table 1 presents the demographic data and baseline measurements.

PGIC
After the first treatment, four out of nine patients rated themselves as improved, five patients after the second treatment, three patients after 6 weeks, two patients after 3 months, and three patients after 6 months.All other participants stated that they had no improvement, but the pain did not get worse.In total, there were 10 ratings of improvement in the electromechanical manipulation group and 7 in the manual manipulation group (see Table 4 for a detailed rating).

Additional interventions
Overall, four participants had additional treatment during the 6 months of follow-up.After 3 months of treatment, two participants visited a physical therapist and one participant received acupuncture once a week.At the 6 months survey, another participant received chiropractic treatment (three times) and one continued to visit a physical therapist, if the neck pain was too severe.

Discussion
The main goal of our pilot study was to compare short-and long-term effects of two different ways of manipulating the thoracic spine in combination with a standardized exercise program for patients with a main complaint of neck pain.In this study, the main outcome was pain intensity using the VAS.We found a significant reduction in neck pain for all patients, but not between the groups.Additionally, there was a tendency and a clinically relevant decrease in neck disability in accordance with the report of Pereira and colleagues that state a reduction of 5.5 points on the NDI in patients with chronic neck pain is a minimal clinically important difference 49 .In particular, the electromechanical group showed a decrease in their VAS scoring of 5.5 after 6 weeks and after 3 months.Although this did not reach statistical significance, we were able to show a tendency for improvement in this group.
However, a wear off in VAS reduction was observed at 6 months.The follow-up of 6 months could have been too long.Patients may have forgotten the details of the interventions.Four of the patients had additional therapy during the follow-up period.Since our groups were small, this might have influenced the outcomes.One suggestion for further research is to use a paper-based or electronic diary to report all possible relevant incidents and interventions 52,53 .
To our knowledge this is the first study that investigated the short-and long-term outcome of electromechanical manipulation.None of the other studies, which were identified during literature review, assessed long-term outcomes of a device with a feedback loop 26,27,29 .Other studies had a follow-up period that lasted only 4 weeks 28 .Huggins and colleagues (2012) postulated the need for more studies evaluating activator adjusting instruments and their long-term outcomes 54 .Patients from previous studies received more treatment than those in our study.Our study had three treatment sessions as recommended by former clinical prediction guidelines 55 27 .Even with the fewer treatment sessions, we could reduce pain significantly.However, in this study, an important difference compared to the other studies is the addition of exercises with the spinal manipulation treatment.The combination of exercise and manipulation is currently the best evidence-based approach for neck pain 6,7 .
One important reason for conducting this study relates to the question on cervical spinal manipulation and serious adverse events such as cervical artery dissection.(see Australian Physiotherapy Association guidelines for vertebrobasilar insufficiency) 8,56 .There is a debate in the literature referring to these events, and this serious complication should be considered if a patient is going to be treated with cervical spinal manipulation (see Australian Physiotherapy Association guidelines for vertebrobasilar insufficiency) 8,[57][58][59][60][61][62][63] .In our study, no serious adverse events occurred.This suggests the treatment of patients with neck pain by manual or electromechanical manipulation of the thoracic spine may provide another treatment option.
From the findings of our pilot study, we calculated the sample size for each time point of a RCT by using the formula 2 × [(1.96 + 0.842) 2 × SD 2 ]/12 264,65 .The calculation revealed that a sample size of 20 per treatment arm at the first time point would be sufficient to show significant differences in outcomes.However, the sample size requirements increased to 24 participants at 6 weeks and 57 participants at 6 months.For a two group pre-test / post-test / follow-up design, a total sample size of 114 participants will be sufficient to reach result with 80% power at an α-level of 0.05.

Limitation
One obvious limitation was the small sample size of the study.One recruitment problem was to find patients who had not received previous manual therapy.Recruitment of chronic patients who were not already treated for their pain condition was therefore especially difficult.Furthermore, our exercise program was not tailored to the individual needs of every patient.This could have influenced the outcome because patients might have needed a more individualized exercise program to approach to their problem, although recent literature suggest, that an individualized treatment is not always superior 66 .Nevertheless, we could show that pain decreased during the intervention.

Conclusion
Neck pain can be influenced by manipulations applied to the thoracic spine in combination with exercise therapy.Additionally, our study suggests that electromechanical manipulations may be able to decrease neck disability.However, caution is advised concerning these results because of the study's small sample size.
The findings of this pilot study allowed the power calculation of the actual sample size needed for a larger randomized controlled trial aimed at studying manipulations applied to the thoracic spine in combination with exercise therapy in patients with neck pain.
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Figure 1 .
Figure 1.Flowchart of the trial, describing the process of randomization, evaluation and treatment.

Dataset 1 .
Complete set of all data recorded as part of this pilot study http://dx.doi.org/10.5256/f1000research.13780.d19247867 . Wood et al. (2001) and Schneider et al. (2011) had eight treatments sessions in 4 weeks 26,29,58 .Shearar et al. (2005) used four treatments over a 2-week period controlled trial was published in May 201530.The study received ethical approval from the Ethics Commission of the Canton of Zurich (2012-0248) and was registered at Current Controlled Trials (ISRCTN88585962).A completed CONSORT checklist can be found in Supplementary File 1.