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Journal of Back and Musculoskeletal Rehabilitation 27 (2014) 435–443 DOI 10.3233/BMR-140464 IOS Press

Does microwave diathermy have an effect on clinical parameters in chronic low back pain? A randomized-controlled trial Dilek Durmusa,∗, Yasemin Ulusa , Gamze Alaylia , Ye¸sim Akyola, Ayhan Bilgicia , Kamil Yazicioglub and Omer Kurua a

Department of Physical Medicine and Rehabilitation, Medical Faculty, Ondokuz Mayis University, Samsun, Turkey b Department of Physical Medicine and Rehabilitation, Gülhane Military Medical Academy, Turkish Armed Forces Rehabilitation Center, Ankara, Turkey

Abstract. OBJECTIVE: The aim of this trial was to investigate the effect of therapeutic microwave diathermy (MD) on pain, disability, trunk muscle strength, walking performance, mobility, quality of life (QOL), and depression in the patients with chronic low back pain (CLBP). METHODS: A total of 39 patients were included in this study. The patients were randomized into two groups. Group 1 (n = 19) received MD treatment and exercises. Group 2 (n = 20) was given only exercises. The pain (visual analog scale), disability (Oswestry Disability Questionnaire and pain disability index), walking performance (6 minute walking test, 6MWT), depression and QOL (Short Form 36) of all participants were evaluated. Patients were assessed before treatment (BT), after treatment (AT), and at a 1-month follow-up (F). RESULTS: The patients with CLBP in each group had significant improvements in pain, disability, muscle strength, endurance, 6MWT, mobility, QOL, and depression AT and F when compared with their initial status. There was no statistically significant difference between the groups regarding the change scores between AT–BT test and F–BT test. CONCLUSION: Since a 2,450-MHz MD showed no beneficial effects on clinical parameters, exercise program could be preferable for the treatment of patients with CLBP alone. Keywords: Chronic low back pain, microwave diathermy, trunk muscle strength, pain, disability, endurance, quality of life, depression

1. Introduction Chronic low back pain (CLBP) is one of the most common health problems that affects 50–80% of adults at some time during their lives. It is also an important medical condition with physical, emotional, and psy-

∗ Corresponding author: Dilek Durmus, Department of Physical Medicine and Rehabilitation, Medical Faculty, Ondokuz Mayis University, Samsun, Turkey. Tel.: +90 362 312 19 19 3091; Fax: +90 362 4576041; E-mail: [email protected].

chosocial consequences that eventually cause deterioration of quality of life (QOL) [1,2]. The purpose of management of the CLBP is to lessen pain, improve mobility and QOL, and minimize disability. Management options include pharmacologic interventions, exercise therapy, and modalities including electrotherapy, cold, and heat therapy. Exercise has an important role in the management of CLBP [3]. It was recently reported that exercise therapy is effective in relieving the pain and disability as well as improving spinal mobility, endurance, proprioception, and strength [4,5].

c 2014 – IOS Press and the authors. All rights reserved ISSN 1053-8127/14/$27.50 

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Techniques for heat therapy include the application of superficial heat and application of electromagnetic energy. Heat therapy has long been used in the management of CLBP. Heat can be administered by a variety of techniques, including ultrasounds, short-wave or microwave diathermy (MD), local application of hot packs or immersion in warm water and wax baths [6, 7]. The resulting hyperthermia is believed to act by increasing local blood flow, which accelerates metabolic processes, thereby facilitating tissue repair and promoting pain relief [8,9]. MD is a well-established deep heating modality that converts electromagnetic energy to thermal energy. Thermal energy is produced by increased kinetic energy of molecules within the microwave Weld. Federal Communications Commission – approved frequencies for therapeutic microwave are 915 MHz (wavelength 33 cm) and 2,456 MHz (wavelength 12 cm). The lower frequency has the advantage of increased depth of penetration but also the disadvantages of greater beam dispersion and the requirement of larger applicators. If muscle heating is primary objective, 915-MHz applicators are preferable to 2,456-MHz applicators. Average temperatures of approximately 41◦ C at a depth of 1–3 cm have been demonstrated [8–10]. Effects of the MD treatment on the clinical parameters (pain, etc.) in the musculoskeletal disorders are controversial [11–14]. While, some investigators found beneficial effects, others did not. In the literature, to the best of our knowledge there is no controlled study investigating the effectiveness of therapeutic MD in the treatment of CLBP. So, in the present study, we aimed to determine the impact of therapeutic MD on pain, disability, trunk muscle strength, walking performance, mobility, QOL, and depression in the patients with CLBP.

housewives, employee, or they were retired (they had been living a sedentary life and had no regular or irregular sports habits). A complete examination was performed by the same physician.

3. Study design This study was prospective, randomized-controlled trial. Before treatment, the patients were informed about the purpose of the study and gave their consent. The study protocol was approved by the local ethics committee. 3.1. Exclusion criteria were the following (1) patients with acute radicular signs or symptoms, (2) those who had radiographic evidence of inflammatory disease affecting the spine, tumor, spondylolisis, spondylolisthesis, or sacroiliitis, (3) serious medical conditions for which exercise would be contraindicated, (4) neuromuscular or dermatologic disease that involves the lumbar and abdominal area, (5) had exercise program that may cause increase of muscle strength within the previous 6 months, (6) specific contraindication to MD (conditions known to be sensitive to increase cell proliferation rates or skin treated in the past 6 months with radiotherapy, ischemia, local thrombosis or defective arterial circulation, impaired cutaneous thermal sensitivity, metal implants, local infections, and indwelling electronic equipment, e.g., pumps or cardiac pacemakers), (7) contracture, (8) previous trauma, (9) history of the spinal surgery, (10) the pregnancy, (11) presence of severe structural deformity. 3.2. Randomization

2. Materials and methods The present study was conducted at the Physical Medicine and Rehabilitation Department of Medical Faculty of “Ondokuz Mayis University”. A total of forty-two female patients who had been experiencing low back pain for at least 3 months were enrolled in the study. Thirty-nine patients completed the study (one patient in the MD group and two patients in the control group could not to be assessed after treatment). A demographic data including age, body mass index (BMI) (kg/m2), educational level, and duration of symptoms (years) were recorded. The subjects were

The patients were randomized into two groups. Randomization was allocated by numbered envelopes method. The same physician who was blind to patients’ clinical data applied the therapy. Group 1 (n = 19) received MD treatment and exercises. For MD, 20 min duration therapeutic MD was applied. For two groups, 60 min duration exercise therapy was applied. Group 2 (n = 20) was accepted as the control group and was given only exercises. All programs were performed 3 days a week, for duration of 6 weeks. Patients were assessed before treatment (BT), at sixth weeks of the therapy (AT), and at a 1-month follow-up (F).

D. Durmus et al. / Effects of microwave diathermy on clinical parameters in low back pain

The use of NSAID, other analgesic drugs, and antidepressant drugs was not permitted during the study period; any pretreatment with these drugs had to be discontinued 7 days before the start of study. The use of other medication for comorbid diseases was permitted during study period. No adverse events had occurred during or after the MD treatment periods. 3.3. Microwave diathermy Curadar 409 (Enraf–Nonius, The Netherlands) was used for active MD treatment. It was equipped with 2,450 MHz microwaves generator with a maximum output power of 100 W. MD was applied for 20 min. 3.4. Exercise therapy All patients came to the outpatient department for exercise treatments. Exercises were taught by a physiatrist. The subjects in both groups received a groupexercise program composed of 60 min back and abdominal exercises with a warm-up and cool-down period of 10 min stretching exercises 3 days a week under the supervision of the same physiatrist. Both groups were given an exercise program, which consisted of 4 exercises: 1. Motion, flexibility, and back strengthening exercises of the cervical, thoracic, and lumbar spine; stretching of the erector spine muscle, hamstring muscles, pelvic muscles, and abdominal muscles: (1) pelvic tilt, (2) knee to chest, (3) lower abdominal exercises, (4) cat and camel, (5) back extension exercises. 2. Special exercises to correct mobility of the spine and hip joints, activate the stabilizing muscles of the spine, and increase flexibility of the lower limb muscles. 3. Functional exercises to improve postural control, dynamic body balance, and coordination. 4. Progressive relaxation exercises to normalize muscle tension.

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higher scores indicating more pain). The Oswestry Disability Questionnaire (ODQ) and pain disability index (PDI) were used to assess pain and disability in the study group. ODQ has 10 subgroups and these are evaluated with 0–5 scores. Subgroups are pain severity, self care, walking, sitting, standing, sexual function, traveling, and social life. The maximum score in ODQ is 70, which means 100% disability [15,16]. Pain disability index has eight subgroups. These are social activities, leisure activities, self care, job, sexual function, daily life activities. Each group is evaluated 0–50 scores. Higher score of the PDI reflects greater disability. 3.7. Walking performance The 6-min walk distance (6MWD) test was used as a test of objective assessment of functional performance and endurance. Subjects were given the same standard verbal instructions before each test and instructed to walk their maximum distance in a 6-min period. The total distance covered in meters during the 6 min of walking was used as the score for each session. 3.8. Muscle strength

The patients were compared before and after the treatment, in accordance with pain, disability, walking performance, abdominal and extensor endurance, isometric trunk flexor muscle strength and extensor muscle strength, QOL, and depression. Pain, walking performance, abdominal and extensor endurance, isometric trunk flexor, and EMS were measured BT and at TS, and at F.

Trunk flexor muscle strength (FMS) and extensor muscle strength (EMS) were measured with a handheld dynamometer (Baseline Push-Pull Dynamometer, Digital (LCD) hydraulic New York, USA) by the same tester. FMS was measured with the subject in supine, arms resting at side, head mid-line. The end piece of the dynamometer was applied on the sternum at the center of the chest. Subject was asked to take 1 or 2 s to come to maximum efort and, then, tester pushed down body as forcefully as possible. EMS was measured with the subject in prone, arms resting at side, head mid-line. The end piece of the dynamometer was applied at the inferior angle of the scapulae on the center of the back between the shoulder blades. Subject was asked to take 1 or 2 s to come to maximum effort and, then, tester pushed down body as forcefully as possible. The maximum force realized during a 3- to 5-s effort was recorded in kilogram. The test was performed three times with a 30-s interval and the average was recorded. Muscle strength was measured before treatment and third and sixth weeks of the therapy.

3.6. Pain and disability

3.9. Endurance

The global pain of the patients was assessed by visual analog scale (VAS) pain score (0–100 mm, with

The subject is placed prone with the legs extended while holding the sternum of the floor. A small pil-

3.5. Clinical assessments

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low is placed under the lower abdomen to decrease the lumbar lordosis. The subject is asked to maintain maximal flexion of the cervical spine, pelvic stability being maintained through gluteal muscle contraction. Subject is asked to maintain this position for as long as possible, to a maximum of 300 s. Endurance time (in s) is recorded by an examiner (extensor endurance test) [17]. The flexor endurance test required subjects to sit on the test bench and place the upper body against a support with an angle of 60◦ from the test bed. Both the knees and hips were flexed to 90◦ . The arms were folded across the chest with the hands placed on the opposite shoulder and toes were placed under toe straps. Subjects were instructed to lift their upper body away from the support and kept it parallel with the support (as instructed by the examiner). Subjects were instructed to maintain the body position as long as possible. The test ended when the upper body fell below the 60◦ angles and came in contact with the back support. Endurance time (in s) is recorded by an examiner [18]. 3.10. Spinal mobility The spinal mobility was assessed by lumbar Schober test, and finger tip to floor distance [19]. 3.11. Quality of life Quality of life was assessed with Short Form 36 (SF-36). The SF-36 is a widely applied generic instrument for measuring health status and consists of eight dimensions: physical functioning, social functioning, physical role, emotional role, mental health, vitality, bodily pain, and general health perceptions. Scores range from 0 (worst) to 100 (best) with higher scores indicating better health status [20]. 3.12. Depression Depression was assessed with Beck Depression Inventory (BDI). BDI is a 21-item test presented in multiple-choice format, which purports to measure presence and degree of depression. Responses are made on a four-point, minimally anchored scale, ranging from 0 to 3, with 3 representing the most severe symptoms [21]. 3.13. Statistical analysis Statistical analyses were performed with SPSS 16.0 for windows. Descriptive data were presented as mean

± standard deviation (SD) or minimum–maximum (median) when needed according to the normal distribution of the parameters. The Shapiro–Wilk test was used to analyze normal distribution assumption of the quantitative outcomes. All outcomes were not normally distributed and evaluated by Wilcoxon sign rank test within each group. To compare the changes of the scores between two groups, Mann-Whitney U test were used. The sociodemographical characteristics of the groups were evaluated by Chi-square test. P values less than 0.05 were considered statistically significant.

4. Results Demographic properties of the patients are shown in Table 1. There was no statistically significant difference for age, gender, BMI, duration of symptoms, job, and education between groups (P > 0.05). There was also no significant difference between the groups in terms of pain, disability, walking performance, trunk muscle strength, endurance, QOL, and depression scores BT (P > 0.05) (Table 2). 4.1. Pain, disability, trunk muscle strength, endurance, and walking test Statistically significant difference was found within groups regarding the VAS pain, ODQ and PDI, trunk muscle strength, endurance, 6MWT, and mobility over time. Compared with initial VAS pain, ODQ and PDI, trunk muscle strength, endurance, mobility, and 6MWT of both groups also showed improvements AT, and these improvements remained unchanged during 1-month follow-up period (P < 0.05). There were no statistically significant differences between the groups for VAS pain, ODQ and PDI, trunk muscle strength, endurance, mobility, and 6MWT regarding the change scores between AT–BT test and F–BT test (P > 0.05) (Table 2). 4.2. Quality of life and depression Statistically significant difference was found within groups regarding the subgroups of SF-36, and depression over time. Compared with initial subgroups of SF36, and depression of both groups also showed improvements AT (P < 0.05). These improvements remained unchanged during 1-month follow-up period. There were no statistically significant differences between the groups for subgroups of SF-36, and depression regarding the change scores between AT–BT test and F–BT test (P > 0.05) (Table 3).

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Table 1 Sociodemographic characteristics of the patients Characteristics

Age (years) Body mass index (kg/m2 ) Duration of symptoms (month) Education Literate Primary education Secondary education College Job Housewife Officer Retired

Group 1 (Microwave treatment, N = 19) Mean ± SD Med (min; max) 56.21 ± 7.00 54 (47; 70) 27.00 ± 3.24 27 (22; 33) 10.26 ± 6.63 10 (2; 30)

Group 2 (Exercise treatment, N = 20) Mean ± SD Med (min; max) 52.90 ± 7.29 54.5 (32; 68) 28.20 ± 3.15 28 (23; 37) 8.60 ± 3.71 9.5 (2; 15)

p

4 (21.1) 4 (21.1) 5 (26.3) 6 (31.5)

3 (15) 3 (15) 6 (30) 8 (40)

0.619

11 (57.9) 2 (10.5) 6 (31.6)

6 (30) 2 (10) 12 (60)

0.178

0.380 0.296 0.444

Mean ± SD: mean ± standard deviation, Med (min;max): median (minimum; maximum); P value is significant when < 0.05. Table 2 Clinical parameters of patients for before treatment and change scores between after treatment-before treatment test and follow up-before treatment test by groups Characteristics

Lumbar shober (cm)

Finger tip to floor distance (cm)

PDI

ODQ (%)

6MWT

VAS pain (cm)

FMS (kg)

EMS(kg)

AET (sn)

EET (sn)

BT AT-BT F-BT BT AT-BT F-BT BT AT-BT F-BT BT AT-BT F-BT BT AT-BT F-BT BT AT-BT F-BT BT AT-BT F-BT BT AT-BT F-BT BT AT-BT F-BT BT AT-BT F-BT

Group 1 (Microwave treatment, n = 19) Mean ± SD Med (min;max) 13.55 ± 0.66 13.5 (12; 15) 0.47± 0.38 0.5 (0; 1) 0.47 ± 0.38 0.5 (0; 1) 4.10 ± 4.14 4 (0; 11) −1.27 ± 1.71 −1 (−6; 0) −1.02 ± 1.63 −1 (−6; 0) 20.78 ± 7.02 21 (7; 37) −13.10 ± 5.48 −13 (−20; −3) −12.50 ± 5.96 −12 (−22; −3) 18.00 ± 4.48 17 (9; 28) −10.22 ± 4.15 −10 (−16; −4) −10.52 ± 4.35 −10 (−15; −6) 470.84 ± 81.93 468 (240; 640) 99.84 ± 4.54 93 (48; 210) 85.78 ± 4.51 80 (47; 210) 6.42 ± 1.50 6 (4; 9) −3.84± 1.67 −4 (−8; 0) −3.36 ± 1.38 −4 (−6; 0) 18.31 ± 2.45 18 (14; 24) 5.34 ± 1.35 5 (2; 8) 4.47 ± 1.30 4 (2; 8) 21.52 ± 3.00 21 (18; 26) 7.18 ± 1.73 7 (2; 12) 6.84 ± 1.42 6 (2; 11) 36.89 ± 16.16 39 (14; 74) 40.63 ± 22.1 30 (5; 97) 36.26 ± 20.03 30 (2; 88) 39.94 ± 33.50 38 (13; 150) 58.68 ± 26.9 52 (23; 104) 52.68 ± 24.2 47 (22; 99)

Group 2 (Exercise treatment, n = 20) Mean ± SD Med (min;max) 13.97 ± 0.89 14 (12; 16) 0.42 ± 0.37 0.5 (0; 1) 0.35 ± 0.46 0.25 (0.5; 1) 2.20 ± 4.61 2 (0; 18) −0.80 ± 0.97 0 (−6; 0) −0.65 ± 1.34 0 (−5; 0) 18.45 ± 12.2 15 (2; 53) −11.75 ± 9.66 −8.5 (−39; −1) −11.40 ± 9.73 −8.5 (−39; −1) 14.95 ± 6.01 15.5 (3; 30) −9.75 ± 4.60 −9.5 (−17; 0) −9.00 ± 4.67 −8 (−14; 0) 501.45 ± 69.38 481 (406; 649) 97.40 ± 4.96 97 (32; 283) 84.30 ± 4.88 80.5 (7; 263) 6.15 ± 0.39 6 (3; 10) −3.50 ± 1.43 −3.5 (−6; −1) −3.15 ± 1.46 −3 (−7; −1) 17.25 ± 2.46 17.5 (12; 21) 6.20 ± 2.68 6 (0; 13) 5.80 ± 3.07 5.5 (0; 15) 20.50 ± 2.48 20 (17; 25) 7.90 ± 2.38 8 (4; 13) 7.30 ± 2.49 7 (3; 13) 38.40 ± 21.01 35.5 (14; 115) 45.00 ± 39.8 32.5 (5; 133) 40.60 ± 38.0 30.5 (0; 127) 53.00 ± 40.24 38.5 (14; 145) 57.40 ± 39.5 45.5 (15; 126) 53.10 ± 37.01 44 (15; 120)

p

0.089 0.728 0.396 0.095 0.659 0.289 0.184 0.052 0.089 0.095 0.678 0.799 0.322 0.052 0.061 0.569 0.496 0.365 0.296 0.064 0.084 0.336 0.298 0.182 0.989 0.588 0.496 0.184 0.569 0.627

ODQ The Oswestry Disability Questionnaire, PDI Pain Disability Index, BT Before treatment, AT After treatment, F follow up, 6MWT 6 Minute Walking Test, VAS pain visual analog scale, FMS Flexor muscle strength, EMS Extensor muscle strength, AET Flexor endurance test, EET extensor endurance test, Mean ± SD Mean ± Standard Deviation, Med (min;max): median (minimum; maximum), P value is significant when < 0.05.

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Table 3 Quality of life and depression measurements of patients for before treatment and change scores between after treatment-before treatment test and follow up-before treatment test by groups Characteristics

Beck depression score

SF-36 subscale Physical function

Social function

Physical role limitation

Emotional role limitation

Mental health

Energy

Pain

General health

BT AT-BT F-BT

Group 1 (Microwave treatment, n = 19) Mean ± SD Med (min;max) 6.57 ± 2.09 5 (1; 8) −3.05 ± 1.98 −4.00 (−8; 0) −3.03 ± 1.59 −3.80 (−9; 0)

Group 2 (Exercise treatment, n = 20) Mean ± SD Med (min;max) 7.70 ± 6.17 6.5 (1; 27) −3.95± 3.53 −3.5 (−13; 0) −3.55 ± 3.45 −3.30 (−13; 0)

0.396 0.647 0.945

BT AT-BT F-BT BT AT-BT F-BT BT AT-BT F-BT BT AT-BT F-BT BT AT-BT F-BT BT AT-BT F-BT BT AT-BT F-BT BT AT-BT F-BT

76.84 ± 11.92 14.47 ± 9.26 12.89 ± 9.90 53.94 ± 16.20 11.10 ± 10.80 10.05 ± 9.58 67.78 ± 28.06 26.25 ± 24.9 0.56 ± 0.47 66.84 ± 25.99 23.31 ± 21.6 17.78 ± 18.9 62.84 ± 13.54 14.73 ± 10.38 12.94 ± 9.47 62.36 ± 8.22 17.63 ± 10.05 13.94 ± 8.75 61.94 ± 12.81 25.47 ± 13.50 21.73 ± 13.53 53.94 ± 16.20 16.57 ± 14.62 13.68 ± 13.10

74.50 ± 12.01 16.25 ± 8.12 14.25 ± 8.19 67.70 ± 18.32 11.85 ± 11.30 9.00 ± 9.15 59.40 ± 31.14 31.10 ± 27.10 0.43 ± 0.57 64.20 ± 25.99 27.30 ± 23.4 24.55 ± 21.6 60.20 ± 12.68 15.95 ± 10.86 13.75 ± 8.79 57.00 ± 11.85 17.50 ± 14.64 14.75 ± 14.18 57.75 ± 13.76 28.60 ± 12.54 24.65 ± 12.99 52.00 ± 14.72 15.75 ± 12.06 13.00 ± 9.65

0.396 0.771 0.901 0.835 0.771 0.749 0.444 0.396 0.380 0.771 0.380 0.336 0.588 0.813 0.687 0.127 0.708 0.771 0.336 0.749 0.667 0.569 0.989 0.901

80 (50; 95) 15 (0; 40) 10 (0; 40) 55 (25; 85) 10 (0; 33) 10 (0; 33) 75 (25; 100) 27.5 (0; 75) 14 (0; 75) 66 (25; 100) 14 (0; 65) 14 (0; 65) 60 (44; 80) 17 (0; 38) 12.2 (0; 38) 65 (45; 75) 15 (0; 40) 10 (0; 30) 66 (44; 88) 31 (0; 55) 24 (0; 55) 55 (25; 85) 20 (0; 55) 10 (0; 50)

77.5 (60; 95) 15 (0; 40) 10 (0; 40) 52.5 (25; 85) 10.5 (0; 33) 8 (0; 33) 50 (25; 100) 27.5 (0; 75) 0.45 (−1; 1) 66 (25; 100) 34 (0; 75) 24 (0; 67) 60 (44; 80) 16.5 (0; 42) 14.5 (0; 32) 55 (25; 75) 15 (0; 55) 10 (0; 55) 55 (44; 88) 32 (0; 55) 23 (0; 55) 52.5 (25; 85) 20 (0; 35) 15 (0; 30)

p

BT before treatment, AT after treatment, F follow up, SF-36 Short Form 36, Mean ± SD: mean ± standard deviation, Med (min;max): median (minimum;maximum), P value is significant when < 0.05.

5. Discussion Several treatment programs exist to decrease pain, to increase mobility, to prevent disability, and to improve QOL and physical functions in the management of patients with CLBP. Medical treatment, superficial and deep heat applications, electrotherapy, massage and traction, and exercises are often administered. Although international guidelines do not recommend the use of these modalities as a sole treatment for musculoskeletal disorders [22–24], physical therapy modalities are very popular in the treatment of musculoskeletal disorders for many years. The physical therapy modalities are usually used in combinations together with the exercises. The effects of the physical therapy modalities on the CLBP have been shown in mostly uncontrolled trials. There are few randomized-controlled studies investigating the effect of these modalities and there is no consensus on which treatment methods are more effective [25–27]. This study was planned as a randomized controlled study to investigate efficacy of

MD on pain, disability, trunk muscle strength, walking performance, mobility, QOL, and depression in the patients with CLBP. The results of present study demonstrated no differences between the treatment group (therapeutic MD + exercise) and the exercise group regarding pain, disability, trunk muscle strength, walking performance, mobility, QOL, and depression. The depth to which microwave energy penetrates varies according to tissue and frequency. Microwaves with a frequency of 2450 MHz penetrate 1.7 cm in muscle and skin, and 11.2 cm in fat and bone, whilst at 915 MHz these values increase to 3.04 cm and 17.7 cm respectively. Experiments with dead pig tissue demonstrate that at 2450 MHz, subcutaneous tissue with a depth greater than 2 cm warms excessively and will reduce the heating of muscle, although at 900 MHz, much less energy is deposited in the superficial layers. Clinical studies have confirmed these findings, although frequency-dependent differences in temperature distribution are much reduced by the forced convection of the circulation [10,28–30].

D. Durmus et al. / Effects of microwave diathermy on clinical parameters in low back pain

To the best of our knowledge, at present, there is no clinical study focusing on the effect of MD on pain, disability, trunk muscle strength, walking performance, mobility, QOL, and depression in patients with CLBP. In the literature, there are limited studies about the effects of MD in patients with musculoskeletal diseases [6,11–14,31–34]. Di Cesare et al. [34] assessed the therapeutic effects of local MD at 434 MHz, three times a week for four weeks on calcific tendinopathy of shoulder in two middle-aged patients. In this case study, authors reported that MD is a safe option in the management of calcific tendinopathy of shoulder. In another study, investigators reported that MD treatment at 434 and 915 MHz can be effective in the short-term management of musculoskeletal injuries [6]. Akyol et al. [11] showed no beneficial effects of MD treatment at 2,450-MHz on subacromial impingement syndrome to pain, shoulder ROM, disability, shoulder muscles and grip strength, QOL, and depression. Similarly, Andrade Ortega et al. [12] determined that MD provides no additional benefit to a treatment regimen of chronic neck pain, that already involves other treatment approaches (e.g. exercise, TENS) in terms of pain, disability, and QOL. In another study, Spiegel et al. [35] and Weinberger et al. [36] demonstrated the beneficial effects of a microwave device operating at 915 MHz with an air cooling system in rheumatoid arthritis patients. Rabini et al. [14] determined the beneficial effects of local MD regimen to shoulder pain and function in the patients with Rotator Cuff Tendinopathy. More recently, Cetin et al. [37] demonstrated that among different physical agents, use of MD before isokinetic exercises in women with knee OA leads to increased exercise performance, reduced pain, and improved function. Giombini et al. [13] and Rabini et al. [7] showed the beneficial effects of MD regimen on moderate knee osteoarthritis to reduce pain and to improve their physical function. In this study [13], they applied 433.92-MHz MD therapy, three 30-min treatment sessions per week for 4 weeks, for a total of 12 sessions [13]. In the present study, the 2,450-MHz MD therapy was performed for 20 min, 3 days a week, for duration of 6 weeks, and a total of 18 sessions. We found no beneficial effect of MD treatment in the patients with CLBP. Since MD was applied for a longer period, lower frequency, and more duration of session in these studies, the improvement in the clinical measurements might be due to the duration of the therapy, duration of session, and difference in frequency. CLBP leads to pain, disability, muscle weakness, and psychological distress, resulting in altered move-

441

ment patterns and functional limitation [38]. The aims of exercise therapy are to correct posture, prevent muscle spasm, strengthen body muscles, increase general aerobic capacity, and maintain active life style [39,40]. Most clinical guidelines for the treatment of CLBP include some form of supervised exercise as an intervention method [41]. According to the most systematic reviews, exercise for CLBP is seen to be effective in decreasing pain and improving function, muscle strength, and QOL [42,43]. Hayden and colleagues [41] stated that, in order to be effective for an exercise intervention program, it should carry fallowing features; individually tailored, delivered in a supervised format, regularly followed-up with the therapist. They also found the most effective exercise program was the one that stressed muscle strengthening. In another study, there is evidence to support the idea that exercises are effective in patients with CLBP in returning to their daily activities, restoring their functionality and work at long-term follow-up [42]. Similarly, some studies conclude that pain intensity and disability are significantly reduced by exercise therapy at short-term follow-up [39,43]. Although a recent Cochrane review emphasizes that exercise is an effective treatment for LBP, no specific exercise program is being pointed out as a more effective method [44]. Up to date, varies exercise programs have been proposed for the treatment of CLBP. Patient characteristics would make selection of specific exercises possible that would create economy in terms of time and the need to supervision, especially considering the fact that these class of patients generally need to continue the exercise program for months and make lifestyle changes to prevent recurrences. Smith and et al. [45] stated that isolated lumbar extension exercise is very effective in reducing pain in CLBP, if pelvis kept stabilized. Shnayderman et al. [46] found that six-week walk training program was as effective as six weeks specific strengthening exercises program. Sorosky et al. [47] declared that yoga and pilates may be helpful tools in managing LBP. Additionally, the importance of core strengthening has been widely recognized in CLBP [48,49]. In the present study, all participants received stretching, strengthening, mobility exercises, and functional exercises to improve postural control, dynamic body balance, and coordination for 60 min with physiatrist. After the treatment, pain intensity, disability level, muscle strength, QOL scores improved significantly in both groups and these improvements remained unchanged during 1-month follow-up period. And there were no significant differences between groups for these clini-

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cal parameters AT and F period. The addition of MD to exercise program for CLBP was not superior to exercise alone. The major limitation of our study is that the limited number of patients in each group. Future studies should include larger populations. Further research is also needed to determine the relative efficacy of diathermy when used as an independent modality. This trial is the first study evaluating the efficacy of MD on pain, disability, trunk muscle strength, walking performance, spinal mobility, QOL, and depression in patients with CLBP. While significant improvements in clinical parameters were obtained with therapeutic MD+exercise and exercise alone in patients with CLBP, we determined no differences between the outcomes of two groups. Considering the time and cost of combination therapy, the comprehensive exercise program, as it is efficient, may be preferable for the treatment of CLBP, alone. However, our results need to be clarified by further studies.

[8]

[9]

[10] [11]

[12]

[13]

[14]

Conflict of interest None.

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