Effect of Transfer Energy Capacitive and Resistive Therapy on Shoulder Pain, Disability, and Range of Motion in Patients With Adhesive Capsulitis: A Study Protocol for a Randomized Controlled Trial

Abstract

Objective

We describe a protocol to evaluate the effectiveness of transfer energy capacitive and resistive (TECAR) therapy on shoulder passive range of motion, shoulder pain, and disability index in patients with adhesive capsulitis.

Methods

This study will be a double-blinded randomized clinical trial with a 1-month follow-up. For the purpose of this research, 30 patients with a 3-month history of shoulder pain and disability diagnosed as adhesive capsulitis will be selected and then randomized into 2 groups, including conventional physiotherapy consisting of electrophysical modalities and therapeutic exercises, which will be given to the control group. In the intervention group, after conventional physiotherapy, 10 minutes of TECAR therapy in resistive mode will be applied on both the anterior and inferior aspects of the shoulder joint. Outcome measures will be related to shoulder passive range of abduction, flexion, and external rotation that will be measured using a digital inclinometer, as well as shoulder pain and disability index that will be assessed by the validated questionnaire. Assessment will be done at baseline, 1 day after the intervention, and by passing 1 month.

Results

The statistical analysis will describe within-group and between-group comparisons; the findings will be illustrated in tables and charts.

Conclusion

Given the reason that the effectiveness of TECAR therapy has not been widely evaluated in adhesive capsulitis, the findings of this pilot study would provide baseline information on the effectiveness and complications of this treatment method and possibly propose a more appropriate protocol for patients with adhesive capsulitis.

Introduction

Adhesive capsulitis (also known as frozen shoulder) is a common glenohumeral joint disorder occurring owing to the raised collagen fiber in the capsule, which consequently results in shoulder capsular thickening, pain, and stiffness.¹ The prevalence rate of primary adhesive capsulitis, which mainly occurs during the fifth and sixth decades of life, is between 2% and 5% among the general population.² Passive external rotation restriction despite normal radiograph is known as the essential clinical feature of the adhesive capsulitis differential diagnosis.³ The average time for restoring shoulder mobility is about 30 months; however, some patients cannot reach a proper functional level.⁴

Physiotherapy is the usual treatment used to prevent the progression of adhesive capsulitis symptoms, which includes joint mobilization, stretching exercises, modalities, and patient education regarding the disease course and modifying daily activities.⁵ Various modalities, such as ultrasound (US), transcutaneous electrical nerve stimulation, and shortwave diathermy (SWD), are used for adhesive capsulitis treatment.⁶ The application of SWD in medical clinics has recently decreased because of safety concerns like the risk of skin burns, especially in patients with metal implants and sensory impairment, and the possibility of radio interference with other devices.⁷ Additionally, US concentrates energy near the bone, increases periosteum inflammation risk, and has a small treatment area.⁸

One of the alternate methods used instead of the above-mentioned modalities for the treatment of musculoskeletal diseases is transfer energy capacitive and resistive or TECAR therapy, which is a deep heat-generating modality delivering radiofrequency energy ranged from 300 kHz to 1 MHz.⁹ TECAR therapy enhances the physiological tissue metabolism by transferring energy and increasing electrolytic motions within tissues, causing the increased deep temperature, microcirculation, vasodilatation, and muscles flexibility.9, 10, 11

TECAR therapy has 2 treatment options using capacitive or resistive electrodes, affecting various tissues. The capacitive electrode concentrates heat in high electrolytic tissues like muscles, and on the other hand, the resistive one generates heat in higher resistance tissues, such as tendons and joint capsules.¹⁰ As well, some unique features have been considered for TECAR therapy compared to other modalities, including the possibility of applying with little to no thermal effects in acute and subacute diseases,¹² as well as the capability of combining physiotherapists' manual techniques and exercises simultaneously with this modality while performing the treatment to make more satisfactory results for both therapist and patient.^9,13

TECAR therapy differs from the other deep thermal modalities, such as SWD and US.⁸ Ultrasound devices have a 1- to 3-MHz frequency, causing slight circular motion in molecules through ultrasonic waves.¹⁴ The SWD machines have an 8- to 14-MHz frequency, which is significantly higher than the TECAR's frequency, and produce external heat.⁸ According to the TECAR manufacturer's statement, there is no limitation on the use of the capacitive mode in areas with metal prostheses; the operator is close to the therapist, with the ability to adjust the power and energy according to the patient's feedback.¹⁵

A recent systematic review indicated that TECAR therapy could effectively improve pain, disabilities, and quality of life in patients with musculoskeletal disorders. This review reported that, although most of the included studies were randomized controlled trials (RCTs), only 2 of them (2/9) had bias with low risk, which recommended designing more standardized trials in order to obtain more concise results.¹⁶

Recent studies have examined TECAR therapy's effectiveness in connective tissue disorders, such as muscles and tendons.^11,13 For example, one study showed the usefulness of TECAR therapy in developing quadriceps flexibility after fatiguing exercise.¹¹ Moreover, another study that used TECAR alone without any therapeutic exercise showed that TECAR therapy significantly improved the Achilles tendon's blood circulation and caused no tendon elongation.¹³ Another study indicated that hamstring flexibility is improved with TECAR therapy and static stretching more than stretching alone.¹⁷

Another study reported that TECAR therapy is the most helpful therapy in tissue healing and pain-relieving if combined with other therapies.¹⁰ Few studies were found on TECAR therapy effectiveness for shoulder disorders in the literature review. One study compared TECAR therapy with sham TECAR in patients with shoulder impingement syndrome, assessed pain and functional impairment with a 2-month follow-up, and finally reported that TECAR therapy significantly improved all variables compared with baseline. Therefore, they considered TECAR therapy as a helpful treatment for these patients.¹²

One study evaluated the effect of TECAR therapy in 22 patients with different cervical and upper limb pathologies, of whom 4 people had shoulder stiffness. As a result, they reported a significant improvement in patient symptoms without any side effect and recommended using TECAR therapy for the treatment of some orthopedic problems.¹⁸

Considering the importance of proper adhesive capsulitis treatment and the lack of rigorous studies, especially RCTs, on the effects of TECAR therapy in adhesive capsulitis management and capsular extensibility, we propose the following study. The purpose of this article is to describe a study protocol to evaluate the effect of this modality on shoulder passive range of motion (SPROM) besides the Shoulder Pain and Disability Index (SPADI), in comparison with conventional physiotherapy in patients with adhesive capsulitis (Table 1). The findings of this study would provide a baseline and implacable information in this field.

Table 1.

List of Outcome Measures

Outcome Measures	Measurement Tool
Pain and disability	SPADI questionnaire
Passive range of motion: abduction, flexion, external rotation	Digital inclinometer

SPADI, Shoulder Pain and Disability Index.

Methods

Study Design

This study will be performed as a 2-arm, parallel double-blinded (patient and assessor) pilot RCT on 30 patients with adhesive capsulitis who will be recruited through advertisements and meetings with the local orthopedic specialist to inform them about the trial's aims and to ask them to refer patients. The participants will be notified of the study's aims, rights to refuse participation at any time, and possible procedure risks by a physiotherapist who is in charge of performing the designed interventions in both study groups. Afterward, they will be asked to sign the written consent before the study initiation. The study will be conducted at a private physiotherapy center in Isfahan, Iran.

This study was approved by the physiotherapy review board and regional ethics committee of Isfahan University of Medical Sciences with the approval code IR.MUI.RESEARCH.REC.1398.447. The Iranian Registry of Clinical Trials registered the present study with the approval code IRCT20191130045550N1.

Participants

The inclusion criteria are chronic patients between 41 and 72 years of age with shoulder pain and stiffness for at least 3 months,¹⁹ Numeric Pain Scale at rest below 7, restriction of passive external rotation besides at least another glenohumeral movement higher than 30° compared with the opposite side, and enough literacy to complete the questionnaire.²⁰

The exclusion criteria are bilateral adhesive capsulitis,²¹ systemic diseases such as rheumatoid arthritis, malignancies, heart diseases, infections, coagulation disorders, full rotator cuff tear,¹⁹ history of recent shoulder surgery, neurological problems involving the upper extremity, shoulder joint osteoarthritis,²⁰ upper extremity fractures, cervical radiculopathy,²² impaired sensation, having a heart pacemaker, pregnancy,²³ physiotherapy treatment in the previous 6 weeks,²⁰ and consuming sedatives or anti-inflammatory drugs.²³

Sample Size

This study will be a pilot RCT because no similar study was found in the literature. The sample size of pilot studies has been recommended to be 12 cases for each group²⁴; thus, the sample size was determined as 15 patients per group for this study by considering a 20% dropout rate.

Allocation and Randomization

All patients who have consent for their participation and meet the inclusion criteria will be assigned into 2 study groups, using randomized block design with a 1:1 allocation, by a therapist who will not be involved in the study. Allocation concealment will be ensured, as the randomization code will not be released until the patient is recruited into the trial and baseline measurements are completed. Conventional physiotherapy will be given to the control group, and conventional physiotherapy, in addition to TECAR therapy, will be given to the intervention group (Fig 1). All patients will be blinded to their study group's assignment. A trained assessor blinded to the treatment allocation will obtain demographic data and outcome measures. All outcomes will be measured at baseline, 1 day after the treatment completion, and after a 1-month follow-up (Table 2). Notably, the physiotherapist, the first author, who will perform the trial procedures, has 4 years of clinical experience in this field.

Fig 1.

Study flow diagram of the randomized controlled trial. SPADI, Shoulder Pain and Disability Index; TECAR, transfer energy capacitive and resistive.

Table 2.

Time Schedule of Enrollment, Intervention, and Assessments

	-1	0		T1	F1
Time point	Pre-study Enrollment and/or Screening and/or Consent	Pre-study Baseline and/or Randomization	Study Intervention (8 Sessions)	1 Day After Study Completion	Follow-Up 1 Month
Enrollment
Eligibility screen	X
Informed consent	X
Demographic data		X
Allocation		X
Interventions
Conventional physiotherapy			X
Conventional physiotherapy + TECAR therapy			X
Assessments
Shoulder passive range of motion: abduction, flexion, external rotation		X		X	X
Shoulder Pain and Disability Index		X		X	X

TECAR, transfer energy capacitive and resistive.

Control Group

The control group will receive 8 sessions of conventional physiotherapy during 3 weeks (3 sessions per week), including modalities and therapeutic exercises in terms of the guideline.²⁵ This protocol will include 5 minutes of continuous US (1-MHz frequency – 1.5-W/cm² intensity) on the anterior-inferior aspect of the shoulder joint,²⁶ 20 minutes of transcutaneous electrical nerve stimulation (80-µs duration – 150-Hz frequency) on the shoulder joint,²⁷ and a home exercise program, including 3 to 4 sets of 10 repetitions per day of wall climbing, pendulum, and stretching exercises (including passive external-rotation stretching, passive horizontal-adduction stretching, passive forward-elevation stretching with the patient supine, and passive internal-rotation stretching in standing position).⁵

Adherence to the home exercise program will be documented daily on a chart given to each patient at the final session. Performing the exercises will be reminded by a phone call every week during the 1-month follow-up. As mentioned earlier, consuming sedatives or anti-inflammatory drugs is considered as one of the exclusion criteria. However, regarding the other medications, participants should continue to take them as usual during trial performance.

Intervention Group

The intervention group will receive the same conventional physiotherapy sessions as the control group, in addition to TECAR therapy (Doctor Tecar, Mectronic, Italy) at the end of each session. In order to apply TECAR therapy, the patient will lie supine, with the passive electrode, a flexible rectangular stainless steel plate measuring 150 × 200 mm, placed under the affected side's scapula. A rigid circular metallic electrode with a 60-mm diameter will be used as the active electrode. Using the resistive mode with the power of 8 to 10 mA, the active electrode will be circularly moved continuously for 10 minutes on the anterior-inferior shoulder capsule while the patient's arm will be held at the end existing range of abduction and external rotation. As well, a manufacturer conductive cream will be used as a coupling medium between the electrodes and the skin. Based on the manufacturer's recommendation for safe performance, the TECAR intensity will be set as the most effective method, causing no pain based on each patient's feedback.

The symptom's progression will be clinically monitored and then evaluated by an independent observer. Any allergic skin reactions, skin hurt, or worsening of the patient's symptoms will be considered as criteria for withdrawing from the trial intervention and reported as an adverse event. Of note, any serious adverse event that is life-threatening will be reported to the regional ethics committee. However, adverse events caused by this treatment are rare; the research team will accept all the costs of treatment if occurred.

Evaluations

Shoulder passive range of motion (abduction, flexion, external rotation) is the primary outcome that will be measured using a digital inclinometer (Baseline 12-1057; Fabrication Enterprises). The interclass correlation coefficient of intrarater reliability for SPROM measurements with inclinometer has been reported to be between 0.66 and 0.82.²⁸

The abduction range will be measured in a standing position, and the flexion and external rotation in supine. The inclinometer device will be fixed on the anterior arm, lateral arm, and distal forearm for abduction, flexion, and external rotation measurements, respectively. It should be noted that the patient's shoulder will be placed in a 45° abduction, if available, and a 90° elbow flexion for external rotation measurement. The maximum pain-free range of each motion will be measured 3 times, and its average value will be considered as the current range.

The second outcome measure is SPADI, a questionnaire used to assess the effects of disease on shoulder pain and disability. This self-administered questionnaire has 13 questions, and each item is scored from 0 to 10. The first 5 items are related to pain severity, and the last 8 parts indicate shoulder function in daily activities. The SPADI is scored between 0 and 100 by averaging the 2 subscale's scores; a score of 0 shows no pain and disability, and a higher score represents higher shoulder pain and dysfunction. The validity and reliability of the Persian version of SPADI have been proven with the internal consistency (Cronbach's α) and an interclass correlation coefficient of 0.94 and 0.84, respectively.²⁹

Statistical Analysis

SPSS software, version 21 (IBM Corp., Armonk, NY), will be used for statistical analysis, and the statistician will remain blinded to the patients’ allocation. The analysis will be performed to describe both within-group and between-group comparisons by passing 1 day from the intervention and after a 1-month follow-up period. The Kolmogorov-Smirnov test will be used to determine the normality of the data; if the distribution is normal, repeated-measures analysis of variance will be used, and if otherwise, the Friedman test will be used. The level of significance will be set at α = 0.05. Qualitative data will be shown in tables and charts.

Data Management

All data will be collected on paper forms and then entered into electronic devices. Participants’ files and information will be kept secure and stored in numerical order, with the right of giving access to all principal trial investigators.

No data monitoring committee will be necessary because of the low harm risk and shortness of the trial duration. There will be no auditing for trial conduct monitoring.

Discussion

This study aims to evaluate the effectiveness of TECAR therapy on SPROM and SPADI in patients with adhesive capsulitis, a disease that consequently results in shoulder pain and stiffness due to capsular contracture. It is documented that increasing tissue temperature to 3°C to 4°C higher than baseline could improve extensibility and help in the treatment of chronic connective tissue disorders and, if combined with stretch simultaneously, have an extra gain on collagen structural changes.^30,31 Deep heat produced by SWD, in addition to stretching exercises, has been reported to be more effective than superficial heat by hot pack or stretching exercises alone in the treatment of adhesive capsulitis.²³

Transfer energy capacitive and resistive therapy, as a new deep thermal modality, has some unique characteristics, including affecting different tissues from muscles to joint capsules without the limitations of other similar modalities, such as US and SWD. Previous studies reported that TECAR therapy could effectively improve muscles flexibility and tendon blood circulation, so it is described as a helpful method for managing musculoskeletal disorders.^11,13,16,17

This study will compare the outcomes of TECAR therapy plus conventional physiotherapy against conventional physiotherapy alone with a 1-month follow-up among patients with adhesive capsulitis and determine which protocol will improve shoulder pain and function more effectively in the short term. Because no study has examined the influence of TECAR intervention on shoulder stiffness to date, it is hoped that the findings of this study will provide valuable data, which might help physiotherapists in selecting the most effective approach in managing this disease, thereby boosting patients’ quality of care and life. There are few studies for comparing this study's findings with theirs in the literature review, so the results of this study could be compared with other studies that evaluated TECAR therapy's effectiveness in different diseases and disabilities.

Conclusion

Given that the effectiveness of TECAR therapy has not been widely evaluated in adhesive capsulitis, the findings of this pilot study would provide baseline information on the effectiveness and complications of this treatment method and possibly determine a more appropriate protocol for patients with adhesive capsulitis.