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ORIGINAL ARTICLE
Year : 2017  |  Volume : 17  |  Issue : 2  |  Page : 93-96

Effect of pulsed electromagnetic field therapy on pain, pressure pain threshold, and pain-free grip strength in participants with lateral epicondylitis


Department of Medical Rehabilitation Sciences, College of Applied Medical Sciences, King Khalid University, Abha, Kingdom of Saudi Arabia

Date of Web Publication6-Jun-2017

Correspondence Address:
Ravi Shankar Reddy
Department of Medical Rehabilitation Sciences, College of Applied Medical Sciences, King Khalid University, Abha
Kingdom of Saudi Arabia
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DOI: 10.4103/sjsm.sjsm_16_17

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  Abstract 

Objective: The objective of this study was to examine the effectiveness of pulsed electromagnetic field (PEMF) therapy on pain, pressure pain threshold (PPT), and pain-free grip strength (PFGS) in participants with lateral epicondylitis (LE).
Methods: A total of 22 participants with LE were included in this pre- and post-test study. All participants received 6 weeks of PEMF therapy. Visual analog scale (VAS) was used to record pain levels, pressure algometer was used to measure PPT in kg/cm2, and a handheld dynamometer was used to measure PFGS in kg.
Results: All the participants improved following 6 weeks of PEMF therapy. VAS score decreased from 7.82 to 3.11, PPT improved from 2.95 kg/cm2 to 4.84 kg/cm2, and PFGS improved from 18.6 kg to 22.1 kg. All the outcome measures showed statistically significant differences (P < 0.001) following pre- and post-comparisons.
Conclusion: PEMF treatment was effective in decreasing pain and improving function in participants with LE.

Keywords: Electromagnetic fields therapy, epicondylitis, tennis elbow


How to cite this article:
Reddy RS. Effect of pulsed electromagnetic field therapy on pain, pressure pain threshold, and pain-free grip strength in participants with lateral epicondylitis. Saudi J Sports Med 2017;17:93-6

How to cite this URL:
Reddy RS. Effect of pulsed electromagnetic field therapy on pain, pressure pain threshold, and pain-free grip strength in participants with lateral epicondylitis. Saudi J Sports Med [serial online] 2017 [cited 2021 Mar 4];17:93-6. Available from: https://www.sjosm.org/text.asp?2017/17/2/93/207569


  Introduction Top


Lateral epicondylitis (LE) (also known as lateral epicondylitis, lateral epicondylosis, tennis elbow, shooter's elbow, archer's elbow, or tendonitis of the affected forearm extensor muscles) is a degenerative tendinopathy characterized by pain at the lateral epicondyle, which is aggravated by resisted muscle contraction of the extensor carpi radialis brevis.[1] LE is most prevalent disorder in workplace requiring repetitive manual tasks (30%–63% of all cases) and it results in decreased function and absenteeism from work.[2] In general population, its prevalence is reported to be 3% and in repetitive hand task occupations 15%, and in tennis players, it is estimated to be 50%.[2],[3]

Different treatment modalities have been mentioned for the conservative management of LE, including ultrasound therapy, steroid injections, taping, hyaluronan gel injections, botulinum toxin injections, topical glyceryl trinitrate, orthotics, nonsteroidal anti-inflammatory drugs, exercise therapy, manual therapy, laser therapy, acupuncture, and surgery.[3] There is a lack of scientific validation for the treatment interventions mentioned in literature. Pulsed electromagnetic field (PEMF) therapy is a conservative noninvasive therapy used for the treatment of pain in different superficial soft tissues.[4],[5] The PEMF therapy is usually administered using a portable medical device that delivers nonthermal, nonionizing pulsed electromagnetic energy to the treatment area without the need for surface or deep electrodes. The scientific evidence suggests that PEMF may induce a localized analgesic effect by modulating factors involved with pain signaling and the inflammatory mediatory response.[6],[7] Clinical studies report that PEMF is an effective therapy for pain relief as an adjuvant in different musculoskeletal conditions.[8],[9],[10] It has various biologic effects on soft tissues. PEMF is used in patients with bone fractures and many musculoskeletal disorders such as osteoarthritis, spondylitis, and rotator cuff tendonitis. Many studies have investigated and reported the benefits of PEMF.[10],[11],[12] However, there are limited studies which evaluate the success of PEMF on tennis elbow.[13] In fact, experimental studies on the biological effects of PEMF encourage the use of this modality for treating tennis elbow. The degeneration in the common wrist extensor tendons that attach to the lateral epicondyle and microtrauma in collagen fibers due to misuse, overuse, and repetitive use are responsible for the occurrence of LE.[14] No thermal effect can be observed in low-frequency PEMF applications. Effectiveness is indicated by changing the cell membrane potentials and ion transport. This leads to an anti-inflammatory effect because the edema is inhibited and microcirculation is enhanced.[15],[16] Furthermore, some in vitro cellular studies have shown that low-frequency PEMF can stimulate collagen synthesis, production, and maintain tendon alignment through the induction of collagen-producing cells and growth factor synthesis, such as transforming growth factors-β.[17],[18] It seems logical that PEMF can decrease edema and induce the healing of collagen fibers in tennis elbow.

In the light of the unmet need for safe, effective, and noninvasive interventions for LE, a pre- and post-test study was conducted to evaluate the analgesic effectiveness of PEMF therapy.


  Methods Top


Study design

A pre- and post-test study was conducted with 22 participants enrolled between November 2014 and February 2016. The study was conducted in the Physiotherapy department of King Khalid University, Saudi Arabia.

Subjects

Twenty-two male and female participants with lateral epicondylalgia aged between 18 and 50 years were screened and enrolled for the study. Inclusion criteria included pain over lateral epicondyle (humeral) while gripping, with resisted wrist extension and passive wrist flexion with elbow extension. Participants excluded if they had any neuromuscular disease, cervical radiculopathy, previous trauma or surgery to elbow, any peripheral nerve entrapment, and congenital or acquired deformities of the elbow. Approval from the Institutional Research Committee and the Institutional Ethical Committee was sought and all participants were asked to read and sign informed consent before the commencement of the study. Each participant was evaluated for pain, pressure pain threshold (PPT), and pain-free grip strength (PFGS) before and after completing 6 weeks of PEMF therapy.

Procedure

A magnetotherapy device (BTL-09, manufactured by BTL Benesov, Czech Republic) was used to produce active PEMF therapy. The affected elbow of each patient was put in a prone position in the middle portion of a big circle solenoid applicator. The dose and application time were selected according to the recommendations of the manufacturer. The total dosage was 6 mT/session. This dose was completed by applying the PEMF at a frequency of 25 Hz and a frequency of 4.6 Hz consecutively. A therapy session lasted for 30 min and 30 sessions were performed during the 6-week period (5 sessions a week for 6 weeks).

Outcome measures

Patients graded their pain using a visual analog scale (VAS). This scale consisted of a simple horizontal line, 100 mm in length, on a white loose leaf of paper.[19] The following wording was used: “Show me your pain level on the line, here is no pain, and there is the worst possible pain.” Patients were asked to mark on the line the point that they felt represented their perception of pain in their current state. The PPT was obtained by applying the 1 cm 2 rubber probe tip of a digital algometer to the most palpably tender site over the lateral epicondyle, with the arm at 30° of abduction and the elbow at 90° of flexion; and with the forearm, wrist, and hand supported. PPT is defined as the pressure at which the participant first felt pain.[20] It was measured 3 times, with 20 s rest intervals between each measurement. For analysis, the mean value (in kg/cm 2) of the three efforts was noted. PFGS was measured with Jamar Hand Dynamometer (Chaitillon) as described by the American Society for Surgery of Hand.[20],[21] Participants were seated on a chair with the elbow flexed to 90° and the forearm in mid prone. Participants were asked to smoothly increase their grip force and to stop pressing at the onset of lateral epicondylar pain. PFGS was measured three times with 20 s rest intervals between each measurement. Mean value (in kg) of the three efforts was noted.

Data analysis

Data analysis was computed using SPSS software Version 20.0 for Windows (IBM-SPSS Inc, Armonk, NY). The normality of the data was analyzed using the Shapiro–Wilk test and by observing the normality curve using a histogram. Since data were found to be normally distributed, a paired t-test was used to compare pre- and post-differences in the VAS score, PPT, and PFGS. The level of significance was set as ≤0.05, which kept the power of the study at 80%.


  Results Top


Twenty-two patients based on the selection criteria (with a mean age of 33.4 years) were enrolled in the study, out of which nine were female. The average duration of symptoms was around 16 months and 20 participants had dominant right side affection. The demographics of the study participants are shown in [Table 1]. Following 6 weeks of PEMF therapy, VAS score decreased from 7.82 to 3.11, PPT increased from 2.95 kg/cm 2 to 4.84 kg/cm 2, and PFGS improved from 18.6 kg to 22.1 kg. All the outcome measures showed statistically significant differences (P < 0.001) following pre- and post-comparisons [Table 2].
Table 1: Demographic characteristics of the study participants (n=22)

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Table 2: Pre- and post-differences for pain, pressure pain threshold, and pain-free grip strength

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  Discussion Top


The study aimed to observe the effectiveness of PEMF on LE, and the results show that this therapy is effective in decreasing pain and improving PPT and PFGS. The original basis for the trials of this form of therapy was the observation that physical stress causes the appearance of tiny electric currents (piezoelectric potentials) that are thought to be the mechanism of transduction of the physical stresses into a signal that promotes the healing of structures such as collagen, cytoskeletal system structures, and the extracellular matrix.[22] PEMF treatment is considered to promote the formation of collagen [23] and human chondrocytes [24] and to accelerate tissue repair.[24],[25]

The results of the current study are in accordance with the Uzunca et al. study.[26] Patients with LE received PEMF therapy for 3 months (5 sessions a week) and showed decreased resting and activity pain levels and improved PPT in the affected elbow. This study differed from Devereaux et al.[27] in 1985. No difference of pain reduction effect could be found after 6 weeks after active PEMF therapy when compared with sham PEMF. Although the improvements in hand-grip strength and thermographic parameters were greater in the PEMF group and continued until the 8th week, the difference between the groups did not reach statistical significance. The study of Devereaux et al. was stopped in the eighth week, and as a result, the long-term benefits of PEMF therapy could not be evaluated.[27] The applied frequency and dosage were also different than the parameters that were used in this study. The difference between the application methods, dosage, and the evaluation time may be the main reasons for the opposite findings of this study.

The nature of the short-term follow-up in this study can be criticized, but the self-limiting character of LE in 8–12 months could confuse long-term results. This study did not have a control group to show the effect purely because of PEMF therapy, and also this study did not consider the daily living activities and functional status of the tennis elbow patients.


  Conclusion Top


PEMF therapy seems to reduce pain and it may be a helpful modality in the conservative treatment of LE. Although the treatment time is quite long and necessitates compliance, it can be used for patients interested in avoiding invasive approaches.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
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