1. Introduction
Chronic Non-Specific Low Back pain (CNSLBP) is defined as pain in the lower back area above the gluteal folds and below the lower margin of the thoracic wall with symptoms that manifest for more than 12 weeks [
1]. Lifetime prevalence of low back pain is 84% with 23% experiencing chronicity in their symptoms and 12% disability [
2]. CNSLBP is typically accompanied by reduced range of motion, long-lasting disability, and a lower quality of life, as well as psychosocial factors such as anxiety and depression [
3]. For more than three decades, low back pain has been the primary cause of disability worldwide, leading to significant expenses for healthcare and lost productivity [
3,
4]. Individuals who experience long-term disability due to chronic or recurring low back pain contribute most of the social and economic costs associated with this condition [
5].
The matter has been extensively researched but optimal therapeutical approach remains to be decided. Manual therapies such as mobilization and manipulation of the lumbar area have provided positive results in dealing with CNSLBP, reducing pain, and improving disability [
6,
7,
8,
9]. Another approach which is widely used in clinical practice and seems to be gaining ground in recent years is the use of Capacitive and Resistive Electric Transfer Therapy (TECAR). Protocols with TECAR utilize radiant energy to produce internal heat and they are used for musculoskeletal disorders due to their ability to relieve pain, relax muscles, and increase elasticity [
10,
11]. The two modes of TECAR therapy are resistive and capacitive, both of which are utilized for their therapeutic properties [
12]. Research evidence suggests that the application of TECAR therapy on the lumbar area improves pain, disability, and range of motion in individuals with CNSLBP [
12,
13] as well as amplifying the therapeutic benefits of exercise [
14]. Modern TECAR devices allow with the use of special electrodes the simultaneous application of TECAR with manual techniques or therapeutic exercise since they turn the hand of the physical therapist into an electrode, providing the possibility of a more dynamic treatment. One such electrode is the resistive electrode bracelet, which allows the emission of radiant energy through the hand of the therapist while they simultaneously apply treatment. However, to date there are no studies investigating the efficacy of applying a manual therapy protocol with a TECAR electrode in people with CNSLBP. The aim of our work is to study the efficacy of the combination of a manual therapy (MT) protocol for the treatment of chronic back pain with the simultaneous application of TECAR using a special electrode bracelet. It has been hypothesized that simultaneous effect of the two therapeutic means through MT and high-frequency current in people with CNSLBP may further improve the therapeutic effects on pain, disability, and lumbar spine mobility than MT alone. Given the wide use of TECAR therapy in physical therapy practice and the lack of high-level clinical studies on the subject, this research has to offer important knowledge on the subject.
3. Results
During December 2022, a total of 78 persons were screened for eligibility. Sixty of them (76.9%) met the inclusion criteria and were randomly allocated into one of the three groups (
Figure 2). No side effects from the treatments were reported in any group during the intervention. All participants attended the entirety of the intervention without any missed session visits or measurement appointments. Regarding dropouts, only one individual, who belonged to the control group, quit the program after two weeks. Demographic characteristics of participants per group are presented in
Table 1.
The two-way ANOVA analysis displayed a significant “Group” x “Time” interaction effect
(p < .001) for the NPRS score, while a main effect on the “Time” factor was observed (
p < .001) (
Table 2). Tukey’s (HSD) post-hoc test displayed a significant difference between groups in the NPRS score from the second week. More specifically, in the second week time point statistically significant differences were found between the two intervention groups (“MT” vs “MT + TECAR”) (
p < .05, 95% CI) as well as between each intervention group with control group (“MT” vs “control” and “MT + TECAR” vs “control”) (
p < .001, 95% CI). In the one-month follow-up time point, between groups differences were found only between each intervention group with control group (“MT” vs “control” and “MT + TECAR” vs “control” (
p < .001, 95% CI).
The two-way ANOVA analysis displayed a significant “Group” x “Time” interaction effect (
p < .001) for the RMDQ score, while a main effect on the “Time” factor was observed (
p < .001) (
Table 2). Tukey’s (HSD) post-hoc test displayed a significant difference between groups from the second week. More specifically, in the second week time point statistically significant differences were found between each intervention group with control group (“MT” vs “control” and “MT + TECAR” vs “control”) (
p < .001, 95% CI). In the one-month follow-up time point, between groups differences were found between each intervention group with control group (“MT” vs “control” and “MT + TECAR” vs “control”) (
p < .001, 95% CI), as well as between the two intervention groups (“MT” vs “MT + TECAR”) (
p < .05, 95% CI).
For the right PPT of L4-L5 paraspinal intervertebral space the two-way ANOVA analysis displayed a significant “Group” x “Time” interaction effect (
p < .001) as well as a main effect on the “Time” factor (
p < .001) (
Table 2). Tukey’s (HSD) post-hoc test displayed a significant difference between groups from the second week. Differences in the second week were found between each intervention group with control group (“MT” vs “control” and “MT + TECAR” vs “control”) (
p < .05, 95% CI). In the one-month follow-up time point, between groups differences were found only between “MT + TECAR” group vs “control” group (
p < .05, 95% CI). For the left PPT of L4-L5 paraspinal intervertebral space the two-way ANOVA analysis displayed a significant “Group” x “Time” interaction effect (p < .001) as well as a main effect on the “Time” factor (
p < .001) (
Table 2). Tukey’s (HSD) post-hoc test displayed a significant difference between groups from the second week. Differences in the second week were found between the “MT + TECAR” group and the other two groups (“MT + TECAR” vs “MT” and “MT + TECAR” vs “control”) (
p < .05, 95% CI). In the one-month follow-up time point, between groups differences were found only between the “MT + TECAR” and the “control group” (
p < .001).
For the right PPT of sacroiliac joint the two-way ANOVA analysis displayed a significant “Group” x “Time” interaction effect (
p < .001) as well as a main effect on the “Time” factor (p < .001) (
Table 2). Tukey’s (HSD) post-hoc test displayed a significant difference between groups from the second week. More specifically, in the second week time point statistically significant differences were found only between the “MT + TECAR” group with “control” group (“MT + TECAR” vs “control”) (
p < .001, 95% CI). Same differences were maintained in the one-month follow-up time point, (“MT + TECAR” vs “control”) (
p < .001, 95% CI). For the left PPT of sacroiliac joint the two-way ANOVA analysis displayed a significant “Group” x “Time” interaction effect (
p < .001) as well as a main effect on the “Time” factor (
p < .001) (
Table 2). Tukey’s (HSD) post-hoc test displayed a significant difference between groups from the second week. More specifically, in the second week time point statistically significant differences were found only between the “MT + TECAR” group with “control” group (“MT + TECAR” vs “control”) (
p < .05, 95% CI). Same differences were maintained in the one-month follow-up time point, (“MT + TECAR” vs “control”) (
p < .05, 95% CI).
The two-way ANOVA analysis displayed a significant “Group” x “Time” interaction effect (
p < .001) for the right quadratus lumborum muscle PPT, while a main effect on the “Time” factor was observed (
p < .001) (
Table 2). Tukey’s (HSD) post-hoc test displayed a significant difference between groups from the second week. More specifically, in the second week time point statistically significant differences were found between each intervention group with control group (“MT” vs “control” and “MT + TECAR” vs “control”) (
p < .05, 95% CI). These differences were maintained in the one-month follow-up time point, (“MT” vs “control” and “MT + TECAR” vs “control”) (
p < .05, 95% CI). For the left quadratus lumborum muscle PPT the two-way ANOVA analysis displayed a significant “Group” x “Time” interaction effect (
p < .001) as well as a main effect on the “Time” factor (
p < .001) (
Table 2). Tukey’s (HSD) post-hoc test displayed a significant difference between groups from the second week. More specifically, in the second week time point statistically significant differences were found between each intervention group with control group (“MT” vs “control” and “MT + TECAR” vs “control”) (
p < .05, 95% CI). These differences were maintained in the one-month follow-up time point, (“MT” vs “control” and “MT + TECAR” vs “control”) (
p < .05, 95% CI).
The two-way ANOVA analysis displayed a significant “Group” x “Time” interaction effect
(p < .001) for the
FTF test score, while a main effect on the “Time” factor was observed (
p < .001) (
Table 2). Tukey’s (HSD) post-hoc test displayed a significant difference between groups in the
FTF test score from the second week. More specifically, in the second week time point statistically significant differences were found between the two intervention groups (“MT” vs “MT + TECAR”) as well as between each intervention group with control group (“MT” vs “control” and “MT + TECAR” vs “control”) (
p < .05, 95% CI). In the one-month follow-up time point, between groups differences were found between the two intervention groups (“MT” vs “MT + TECAR”) (
p < .05, 95% CI), as well as between “MT + TECAR” and control groups (“MT + TECAR” vs “control”) (
p < .001, 95% CI).
4. Discussion
In our research, the same MT protocol was applied with and without the application of a TECAR high-frequency current to investigate whether the simultaneous application of the two means could be more effective, compared to the individual application of MT, in the treatment of symptoms in people with CNSLBP. Modern TECAR devices are widely accepted in clinical practice, allowing with special electrodes the simultaneous application of high-frequency current with therapeutic applications such as manipulation, mobilization, or therapeutic exercise. However, their efficacy has not been proven in clinical studies. Research data surrounding the applications of TECAR both in the treatment of CNSLBP [
12,
14,
27] as well as its use in other musculoskeletal disorders [
10] concern the conventional applications of these devices using simple capacitive and resistive electrodes.
The mechanisms to achieve analgesia are known. In manual therapy, the therapeutic manipulations are able, through the mobilization of the tissues and stimulation of the sensory receptors, to block the noxious stimuli of the pain receptors and simultaneously increase the local circulation, the temperature, and the local metabolism at the cellular level [
28,
29]. However, the analgesic effect of manual therapy is mainly based on mechanical stimuli while the thermal effect produced has been shown to be negligible and limited only to the superficial muscles [
28].
On the other hand, the high-frequency current emitted by a TECAR device produces an intense thermal effect in depth at the different tissue levels (muscles, tendons, cartilage, joints, and bones). Generating this deep heat through radio frequency emission has been shown to greatly increase cellular metabolism and provide intense analgesic and healing action reducing recovery time [
10].
The study was conducted on the assumption that the simultaneous emission of the high-frequency current with another means such as the therapeutic manipulations of the care provider combines the therapeutic effects of manual therapy with the effect of deep heat and possibly enhances the analgesic effect. By maintaining consistent conditions throughout the application of the ΜΤ protocol, both with and without the application of TECAR therapy, and at the same time by ensuring sample homogeneity in terms of initial measurements and demographic characteristics, any distinction between the groups can be attributed to the cumulative impact of the MT and TECAR therapeutic means.
The results of this research show that the application of the same MT protocol using a resistive electrode bracelet further improved the pain of participants. The NPRS score improved significantly in both intervention groups compared to the control group in the second week while this difference was maintained at the one-month follow-up (
Table 2). However, the decrease in NPRS score noted in the MT + TECAR group (-2.85 points corresponding to a reduction of 49.23%) was greater than that of the MT group (-2 points, 32.78% reduction) with a statistically significant difference in the second week. A possible explanation for this is that the combined effect of MT and deep heat produced by TECAR led to the maximum analgesic effect further reducing the NPRS score. The difference between the two intervention groups in the second week is clinically important to us as according to Ostelo et al. [
30] the minimally clinically important change in the NPRS score in individuals with CNSLBP is 2.5 points, which was observed only in the MT + TECAR group. However, it is worth mentioning that the difference in the NPRS score between the two groups did not remain statistically significant during the one-month follow-up, possibly due to the short intervention period. Perhaps the two weeks were not enough to maintain this difference at the same levels one month after the intervention. We concluded therefore that more long-term interventions should be implemented in the future to capture the effects of this treatment protocol in people with CNSLBP.
Our results agree with those of Tashiro et al. [
14], who also found similar positive effects on pain by adding TECAR to a therapeutic exercise program in individuals with CNSLBP. However, they used conventional TECAR electrodes without the simultaneous application of other therapeutic means through a special electrode bracelet as in our study, so a direct comparison of the results is not possible.
Corresponding differences between the groups were also noted in the RMDQ score. Both intervention groups showed statistically significant differences compared to the control group from the second week, which differences remained statistically significant during the one-month follow-up measurement. A difference was also found from the second week between the two intervention groups with the MT + TECAR group showing an improvement in the score compared to the initial measurement by 51.91% (6.1 points decrease) compared to the MT group which improved by 36.4% (4.15 points decrease). However, the differences between the two intervention groups appeared statistically significant only at the one-month follow-up with bigger mean differences between groups at the one-month follow-up related to the second week (3.05 and 2.6 respectively). This fact can be partially explained by the generally lower levels of pain experienced after the intervention by the participants of the MT + TECAR group compared to the participants of the MT group, which is also reflected by the results of the NPRS score. The difference between the two intervention groups at the one-month follow-up is also clinically significant as according to Ostelo et al. [
30] the minimally clinically important change in the RMDQ score in individuals with CNSLBP is 3.5 points. This difference was only noted in the participants of the MT + TECAR group and not in the participants of the MT group (
Table 2). The results of our research agree with those of other researchers who also found a corresponding reduction in disability with TECAR therapy in combination with exercise [
14].
Regarding the PPT values of the L4-L5 paraspinal intervertebral space on the right side, statistically significant differences were detected between the two intervention groups and the control group in the second week, while at the one-month follow-up differences were detected only between the MT + TECAR group and the control group. A possible explanation is the greater increase in the PPT value noted in the MT + TECAR group compared to the other two groups. It appears that even if the difference between the two intervention groups in the second week did not appear statistically significant, the improvement in the MT + TECAR group was maintained at high levels one month later in contrast to the MT group. This possibly explains why the MT group did not show statistically significant differences compared to the control group at the one-month follow-up (
Table 2). Therefore, it appears that the combined effect of MT and TECAR made the improvements in PPT last longer.
Concerning the L4-L5 paraspinal intervertebral space PPT on the left side, in the second week differences were detected between the two intervention groups as well as between the MT + TECAR group and the control group, which remained statistically significant during the one-month follow-up (
Table 2). Consequently, the PPT value in the MT + TECAR group (presented numerically in
Table 2) was much higher than the other two groups and this improvement was maintained one month after the intervention. On the other hand, the improvement in value noted in the MT group in the second week was not maintained one month later, which is confirmed by the fact that there were no differences between the MT group and the control group at the one-month follow up.
Regarding the sacroiliac joint PPT on both the right and left sides, the only differences noted in the second week were between the MT + TECAR group and the control group. In fact, these differences remained statistically significant during the one-month follow-up, which means that the improvement noted in the participants of the MT + TECAR group (shown numerically in
Table 2) was greater than that noted in the participants of the other two groups. Even if no statistically significant differences were noted between the two intervention groups at any time point, the fact that no corresponding differences were noted between the MT group and the control group is for us an indirect indication that the MT + TECAR approach appeared more effective than the other two in increasing PPT.
The improvements observed in the PPT values in both the L4-L5 paraspinal intervertebral space and the sacroiliac joint in the participants of the MT + TECAR group appear to be due to the combined effect of MT and TECAR. It is possible that the combination of mechanical (MT) and thermal (TECAR) effects at the same time increased the PPT values more effectively and for a longer period
Regarding the quadratus lumborum muscle PPT, both on the right and left sides, differences between the groups were detected in the second week between the two intervention groups and the control group, while these differences remained statistically significant at the one-month follow up. However, although
Table 2 shows that the improvement of the quadratus lumborum muscle PPT was greater in the participants of the MT + TECAR group compared to those of the MT group, this difference did not appear to be statistically significant. Therefore, we can say that the additional application of TECAR did not seem to add a significant additional positive effect to the improvement of the quadratus lumborum muscle PPT. On the question of why the addition of TECAR seemed to contribute more to the improvement of PPT values in the L4-L5 paraspinal intervertebral space as well as the sacroiliac joint while the same did not happen with the PPT of the quadratus lumborum muscle, a possible answer is as follows: The first two points refer to areas of the body that also contain non-contractile elements (tendons, joints, and bones), while the quadratus lumborum muscle contains soft tissues. The special bracelet electrode used to apply most of the MT manipulations in the MT + TECAR protocol was a resistive electrode, which according to the manufacturer causes a temperature increase more in areas of the body poor in fluid such as ligaments, joints, and bones and less so in muscles [
12]. More research in the future can study the effects on the different tissues of the combined MT and TECAR protocols using special electrodes depending on the target areas and depending on the operating method of the device (capacitive or resistive). In a recent study, no differences were found between the two operating methods of TECAR in individuals with CNSLBP [
12]. However, the researchers did not study the combined effect of MT and TECAR and applied their protocol with conventional TECAR electrodes. We believe that more research is needed on different combined MT and TECAR protocols using specific capacitive and resistive electrodes to have a clearer picture of their analgesic effect on different tissues.
Finally, the results of the FTF test score showed that it improved significantly in both intervention groups compared to the control group in the second week, while this difference was maintained at the one-month follow-up (
Table 2). However, the improvement in the FTF test score found in the MT + TECAR group was greater than that of the MT group with a statistically significant difference in the second week (-9.25cm, 58.91% reduction) compared to the corresponding reduction observed in the participants of the MT group (-4.3cm, 27.21% reduction). This further improvement of lumbar mobility observed in participants of the MT + TECAR group may be due to the thermal effect of TECAR. It is known that the application of TECAR increases joint mobility, especially in stiff joints and increases the range of motion [
10]. However, it is not clear from our own research whether this improvement is due to the combined effect of MT and TECAR or to the effect of TECAR alone (as for this there would have to be another group doing TECAR alone). Finally, it is worth noting that at the one-month follow-up differences were only found between the MT + TECAR group and the other two groups, which means that the individuals in this group not only showed greater improvement compared to the individuals in the other two groups, but this improvement also had a longer duration
This study had several limitations. The fact that neither participants nor care providers were blinded to the study aims was a threat. The small number of participants in combination with a short follow-up period were also a significant limitation of this research.
Author Contributions
Conceptualization, K.K., P.I., D.L., G.K. and T.A.; methodology, I.P.C., G.K., D.L., P.I. A.F. and G.T.; software, I.P.C., D.L., N.K., A.S. and T.A. validation, I.P.C., D.L. and G.C.; formal analysis, I.P.C., K.K. and G.T.; investigation, G.K., K.K., A.F., S.R.N. and P.I.; resources, G.K., I.P.C., D.L., P.I., K.K., A.F. and G.C.; data curation, I.P.C., D.L. and P.I.; writing—original draft preparation, K.K., P.I., D.L., G.K., I.P.C., A.F., S.R.N., N.K., A.S., G.C., G.T. and T.A.; writing—review and editing, T.A., G.K. and P.I.; visualization, G.K. and I.P.C.; supervision, T.A.; project administration, T.A.; funding acquisition, T.A. All authors have read and agreed to the published version of the manuscript.