Effectiveness of Different Frequencies of Interferential Therapy on Pain and Disability in Individuals with Low Back Pain: A Randomized Controlled Trial Study

INTRODUCTION

Low back pain (LBP) is described as pain in the low back region below the T12 level and above the buttocks level. The paIn can be classified into two types: acute, which lasts 1–2 months, and chronic, which lasts 2–3 years.^[1,2] LBP makes regular day activities difficult in patients with the pain, which can be specific or nonspecific. LBP is caused by a structural problem in the spine or muscle spasm in the lumbar muscles. Some LBP can radiate to the legs because of nerve involvement. Globally, more than 600 million individuals are affected by LBP, making their day to day activities harder.^[3,4] The condition has a significant impact on individuals, families, and society, particularly among the working-age population, where it leads to reduced productivity, work absenteeism, and economic burden.^[5,6] LBP also affects mental health, work capacity, and income. Both acute and chronic LBP are associated with higher disability rates, further increasing the socioeconomic burden. Interferential therapy (IFT) is a commonly used electrotherapy modality in physiotherapy for pain management. It involves combining two medium frequencies to produce one low-frequency current and interfering with the tissue to treat it.^[7,8] The IFT promotes an analgesic effect in the physiological mechanism by inhibiting the nociceptive transmission in the spinal cord, which releases the endogenous opioids as beta-endorphins that bind to the pain perception in the central nervous system. Despite the widespread clinical use of IFT, there is limited evidence regarding the optimal frequency parameters for effective pain reduction and improvement among individuals [Figure 1]. In routine clinical practice, frequency selection is often based on experience. Therefore, comparing the effectiveness of different frequencies of IFT is essential to optimize treatment outcomes and establish standardized physiotherapy protocols for managing LBP.^[9,10]

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Figure 1: Mechanism of interferential therapy (IFT).

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MATERIAL AND METHODS

The control group

In the control group, the participants were given IFT with Quadripolar AMF along with standardized physiotherapy treatment, such as pelvic bridging as showed in Figure 2 (a), to increase the strength of the low back muscles. Knee to chest (b) is given to improve the stability of the lower pelvis, which is one of the bases of the Willian flexion exercise. Cat and camel exercise (c) is used to improve spinal flexibility, reduce back pain, and strengthen core muscles. Lunges (d) are given to strengthen the quadriceps, hamstrings, Glutes, and core muscles. Crunches (e), to strengthen the transverse abdominis (deep core muscle) and erector spinae. Finally, a straight leg raise (f) is given to strengthen the core and improve lower back support. All these were prescribed and given for 2 weeks, and a set of 3 with 10 reps was advised. A total of 52 participants were placed in the control group.

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Figure 2: Exercises (a) Pelvic bridge: The participants were encouraged to lie down with trunk straight. Next we instructed them to bend their both the knees while both the arms resting on the exercise couch, followed by this with the help of hand and foot support asked them to lift the abdominal (stomach) area while upper trunk have to be in contact with the couch. The position has to be maintained for 5–10 s. (b) Single knee to chest and double knee to chest: In single knee to chest exercise the participants were encouraged to lie down facing upward. The instruction given to them are bend your one knee and bring them toward your chest to enhance the stretching in lowerback and back of your gluets hold the flexed knee with both the hands. While the other leg kept in the relaxed position. They have to maintain the position for 15–20 s and return to normal position. Whereas in double knee to chest the participants were instructed to repeat the same instead of one knee bending here both the knees has to be bent and others remains same as above. (c) Cat and Camel: In Cat and Camel exercise the participants were instructed to be in quadruped position. For camel pose they were asked to hunch their spine backward which looks like a camel hump and for cat pose they were asked to bend their spine inward. For both the positions they had to maintain the positional stretch for 10– 15 s and come back to normal position. (d) Lunges: In lunges exercise, participants were instructed to kneel down (i.e.) starting position of the exercise. To start the exercise the participant has to place one leg forward to the maximum range they can at the same time trunk has to be in neutral position. Repeat the same for the other leg too. (e) Crunches: The participants were instructed to lie down on the exercise couch then asked to bend both the knees while the head, trunk, and foot contact with the couch. Followed by this they were asked to fold their hands in order to not to be in contact with the couch, then lift their head and shoulder off the exercise couch while the back and foot remains in contact with the couch, hold the position for 10–15 s. Then come back to neutral position. (f) Straight leg raises: In straight leg raise the neutral position is lying facing upward. They were instructed to raise one leg straight without bending the knee upto their pain free range while the other leg remains in neutral position. Hold the position for 15–20 s. Return to normal position. Repeat the same exercise for the other leg too.

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NPRS

A patient marks their current level of pain on a 10-cm line with “no pain” at one end and “worst imaginable pain” at the other. The NPRS pain score is the measurement in centimeters from the “no pain” side, which aids physicians in determining the severity of pain for treatment decisions. The pain measurement is marked using the NPRS scale, which indicates 0 as no pain, up to 10, which is the most severe pain. The value is taken before and after the treatment, so we know whether the pain decreased or not.

ODI

The ODI is used to assess the functional disability in individuals with LBP using a 10-point set of questions, each valuing 0~5. The questions focus on pain intensity, personal care, lifting, walking, sitting, standing, sleeping, social life, traveling, and employment or homemaking. The total marking was calculated using the overall points from all sections using the formula percentage of (total score/50) ×100.

RESULTS

A control group (n = 52) and an experimental group (n = 50) comprised the 102 participants in the study. There was a slightly higher percentage of females in both groups, but the gender distribution was similar.

The experimental group’s mean age was (45.67 ± 8.42) years, while the control group’s was (46.78 ± 7.36) years. Both groups’ average pain duration before intervention was roughly 59 days, with comparatively high standard deviations showing participant variability. Anthropometric measures such as height and weight were closely matched between the groups.

Baseline pain intensity, as measured by the NPRS, was slightly higher in the experimental group (7.09 ± 0.9) than in the control group (6.24 ± 0.72). The ODI scores reflected severe baseline disability in both groups, with mean scores of 69.20 ± 10.7 and 71.10 ± 10.5, respectively.

DISCUSSION

A total of 102 participants completed the 2-week study, and reported no aftereffects from taking the IFT treatment along with standard exercises. This shows the effectiveness of IFT treatment in LBP.^[10,11] The quadripolar application produced a strong analgesic effect. In this study, the quadripolar technique demonstrated better outcomes because it effectively distributes the electric field, penetrating the deep tissues of the lumbar region to activate pain-inhibitory mechanisms, such as spinal gate control and endorphin-mediated analgesia and clinical data at baseline were similar in the experimental and control groups, and there were no statistically significant differences found between the two groups provided in Table 1. This showed that any differences found in pain and disability outcomes could be attributed to the intervention and not to any existing differences between the groups.

There was a significant pain reduction in the intervention group who had completed the 2-week sessions as displayed in Table 2. The complete standard exercise and IFT show a better pain reduction in the NPRS score and improvement in the functional ODI score than the control group.^[12,13] When comparing both groups, the experimental group showed a better reduction of pain than the other group as listed in Table 3. The quadripolar method showed a significant reduction of pain with standard exercises. The NPRS and ODI score changes examined in pre-post value showed a minimal clinically important difference and minimal detectable change in the mean value. This not only shows the experimental group’s statistical improvement, but also clinical improvement. When it comes to pain reduction, the quadripolar group results have higher data (p < 0.001) than the control group. The quadripolar method produces a high analgesic effect. The quadripolar shows a better outcome in the study because it distributes the current filed, which penetrates the deep tissue of the lumbar and activates the pain inhibitory mechanism, such as spinal gate control and endorphin-mediated analgesia. The importance of the study is that it compares the direct difference between two methods of IFT, which are quadripolar versus bipolar, and the frequency modulation in managing the LBP and the clinical standardized protocols.^[14,15] Quadripolar IFT produces a greater analgesic effect than bipolar due to its deeper tissue penetration, enhancing the pain-inhibitory pathways. This study also shows the greater role of exercise in restoring function in the lumbar region and reducing the stress that occurs due to mechanical stress. The exercises consist of core stability, spine control, postural correction, and improvement in mobility of the spine. The study showed a great result in the management of LBP using electrotherapy combined with exercise. This produced a good improvement compared to an exercise-alone in physiotherapy. The significance of this research is that it shows quadripolar IFT gives a moderate analgesic effect, which is comparable to that of pharmacological intervention agents such as ibuprofen. IFT provides a non-invasive method for reducing back pain with low side effects, making it useful in long-term management of musculoskeletal pain.

The implication of this study is to add IFT quadripolar to managing mechanical LBP, along with exercises to achieve a faster pain reduction in acute and chronic stages. However, it is important to acknowledge certain limitations of the study. The short duration of intervention (2 weeks) and the absence of long-term follow-up limit the ability to determine the sustained effects of treatment. Moreover, pain and disability were self-reported measures and this may introduce subjective bias. Future research involving larger sample sizes, longer follow-up periods, and objective outcome measures such as electromyographic activity or functional performance tests is warranted . Even with the limitations stated above, this study provides valuable evidence which supports the use of quadripolar IFT in physiotherapy practice. It serves as a good foundation for future randomized controlled trials to explore the frequency and duration of the management of LBP.^[16-18]

CONCLUSION

The study showed comparable demographics in both the experimental and control groups, which consisted of age, gender, pain duration, and disability level. The outcome measures (NPRS and ODI scores) demonstrated statistically significant improvements across the groups, suggesting the efficacy of the therapeutic approach. The statistical data support the data distribution of parametric analysis, which reinforces the reliability of these findings. This intervention proves the clinical value of managing LBP with an effective strategy in treating the condition. This study supports the use of the IFT quadripolar method in treating LBP, which greatly reduces the pain rating. The findings suggest that quadripolar IFT combined with exercise may offer greater short-term effectiveness compared to bipolar IFT with exercise.