Ultrasound-Guided Percutaneous Electrolysis Plus Exercise for Chronic Supraspinatus Tendinopathy

\*\*Background and Rationale\*\*

Chronic supraspinatus tendinopathy is a frequent cause of rotator cuff-related shoulder pain and is associated with impaired shoulder function, reduced tolerance to mechanical loading, and limitations in daily activities. Progressive exercise-based rehabilitation is widely recommended as a first-line conservative treatment. However, clinical outcomes remain heterogeneous, and additional therapeutic strategies may be beneficial for patients with persistent symptoms.

Ultrasound-guided percutaneous electrolysis (EPI) is an invasive physiotherapy technique involving the application of a low-intensity galvanic current through a solid filiform needle inserted into the affected tendon under ultrasound guidance. Experimental evidence suggests that galvanic stimulation may activate biological pathways associated with tendon remodeling and collagen production, although the clinical relevance of these mechanisms remains uncertain.

Previous randomized controlled trials have reported favorable outcomes following percutaneous electrolysis in individuals with supraspinatus tendinopathy. However, the additional clinical benefit of combining this intervention with a standardized progressive exercise program has not been fully established.

\*\*Study Objectives\*\*

The primary objective of this study is to determine whether adding ultrasound-guided percutaneous electrolysis to a standardized exercise rehabilitation program results in greater improvements in shoulder pain and disability compared with exercise therapy alone in individuals with chronic supraspinatus tendinopathy.

Secondary objectives include evaluating changes in pain intensity, pain-related self-efficacy, and active pain-free shoulder range of motion, as well as monitoring intervention-related adverse events.

\*\*Study Design\*\*

This study is designed as a prospective, two-arm, parallel-group randomized controlled trial with blinded outcome assessment.

Participants will be randomly allocated in a 1:1 ratio to either an experimental group receiving ultrasound-guided percutaneous electrolysis combined with exercise therapy or a control group receiving exercise therapy alone.

Randomization will be performed using a computer-generated allocation sequence. Allocation concealment will be maintained using sequentially numbered, opaque, sealed envelopes prepared by an independent researcher.

Outcome assessors and data analysts will remain blinded to group allocation. Blinding of participants and treating physiotherapists will not be feasible because of the nature of the interventions.

\*\*Intervention Protocol\*\*

Both groups will participate in a standardized six-week exercise-based rehabilitation program consisting of progressive rotator cuff strengthening, eccentric loading of the supraspinatus tendon, and scapular stabilization exercises.

The rehabilitation program will include one supervised physiotherapy session per week and daily home exercises. Exercise intensity and progression will be individualized according to participants' symptoms, perceived exertion, and tolerance to mechanical loading.

Participants assigned to the experimental group will additionally receive ultrasound-guided percutaneous electrolysis once weekly for six consecutive weeks.

The electrolysis procedure will be performed under real-time ultrasound guidance to identify the affected region of the supraspinatus tendon and ensure accurate needle placement. A sterile filiform needle will be inserted into the target tendon region, followed by the application of a low-intensity galvanic current.

The electrolysis protocol will consist of a continuous galvanic current of 350 microamperes applied for 72 seconds during each treatment session.

Both groups will receive the same exercise rehabilitation program to isolate the additional clinical effects of percutaneous electrolysis.

\*\*Outcome Assessment\*\*

Clinical assessments will be conducted at baseline and six weeks after the beginning of the intervention.

The primary outcome will be the change in shoulder pain and disability measured using the Shoulder Pain and Disability Index (SPADI).

Secondary outcomes will include pain intensity at rest, during shoulder movement, and at night; pain-related self-efficacy assessed using the Pain Self-Efficacy Questionnaire (PSEQ); and active pain-free shoulder range of motion measured using standardized goniometric procedures.

Adverse events potentially associated with the interventions, including post-needling soreness, minor bleeding, bruising, vasovagal reactions, and symptom exacerbation, will be monitored throughout the intervention period.

Treatment adherence will be assessed using exercise diaries, supervision records, and attendance at scheduled treatment sessions.

\*\*Expected Contribution\*\*

This study aims to provide additional evidence regarding the clinical effectiveness of ultrasound-guided percutaneous electrolysis as an adjunct to exercise-based rehabilitation in individuals with chronic supraspinatus tendinopathy.

The findings may help clarify whether combining a tendon-directed intervention with progressive therapeutic loading provides additional short-term clinical benefits compared with exercise therapy alone.

Participants in this group will receive ultrasound-guided percutaneous electrolysis combined with a standardized exercise-based rehabilitation program over six weeks. Both interventions will be delivered concurrently throughout the treatment period.

Procedure: Ultrasound-Guided Percutaneous Electrolysis

Participants in this group will receive the same standardized six-week exercise-based rehabilitation program as the experimental group, without the addition of percutaneous electrolysis.

Behavioral: Progressive Exercise-Based Rehabilitation

Ultrasound-guided percutaneous electrolysis will be administered once weekly for six consecutive weeks by an experienced physiotherapist.

Following skin disinfection with chlorhexidine, a sterile filiform needle (0.30 × 40 mm) will be inserted into the affected region of the supraspinatus tendon under real-time B-mode ultrasound guidance using a high-frequency linear transducer.

A continuous galvanic current of 350 microamperes (µA) will be applied for 72 seconds, corresponding to an electrical charge of approximately 25.2 millicoulombs per session.

A single application will be performed during each treatment session, targeting the tendon region showing the greatest ultrasonographic alterations.

No local anesthetic will be administered. Participants will receive six electrolysis sessions in addition to the standardized exercise rehabilitation program.

Participants will complete a standardized six-week exercise-based rehabilitation program comprising progressive rotator cuff strengthening, eccentric loading of the supraspinatus tendon, and scapular stabilization and motor control exercises.

The program will include one supervised physiotherapy session per week and daily home exercises.

Rotator cuff strengthening will involve isometric and isotonic exercises performed in the scapular plane. Eccentric supraspinatus exercises will emphasize a controlled lowering phase lasting 3-4 seconds. Scapular exercises will target the serratus anterior and lower trapezius muscles.

Exercises will be prescribed as three sets of ten repetitions. Load progression will be individualized according to symptom tolerance, allowing pain of no more than 3/10 during exercise and no symptom exacerbation within the following 24 hours.

The same exercise protocol will be administered to both treatment groups.

Plazo: Baseline and 6 weeks

Shoulder pain and disability will be assessed using the Shoulder Pain and Disability Index (SPADI), a validated 13-item self-reported questionnaire comprising pain (5 items) and disability (8 items) subscales. The total score ranges from 0 to 100, with higher scores indicating greater shoulder pain and disability. The primary outcome will be the change in the SPADI total score from baseline to week 6, calculated as the week 6 score minus the baseline score. Negative changes indicate improvement.

Plazo: Baseline and 6 weeks

Pain intensity at rest will be assessed using an 11-point Numerical Rating Scale (NRS), ranging from 0 (no pain) to 10 (worst imaginable pain). Participants will report their average pain intensity at rest. Changes will be calculated as the week 6 score minus the baseline score, with negative values indicating pain reduction.

Plazo: Baseline and 6 weeks

Pain intensity during shoulder movement will be assessed using an 11-point Numerical Rating Scale (NRS), ranging from 0 (no pain) to 10 (worst imaginable pain). Participants will report their average pain intensity during shoulder movement. Changes will be calculated as the week 6 score minus the baseline score, with negative values indicating pain reduction.

Plazo: Baseline and 6 weeks

Night pain intensity will be assessed using an 11-point Numerical Rating Scale (NRS), ranging from 0 (no pain) to 10 (worst imaginable pain). Participants will report their average shoulder pain intensity experienced at night. Changes will be calculated as the week 6 score minus the baseline score, with negative values indicating pain reduction.

Plazo: Baseline and 6 weeks

Pain-related self-efficacy will be evaluated using the Pain Self-Efficacy Questionnaire (PSEQ), a validated 10-item self-report instrument assessing confidence in performing daily activities despite pain. Total scores range from 0 to 60, with higher scores indicating greater pain self-efficacy. Changes will be calculated as the week 6 score minus the baseline score, with positive values indicating improvement.

Plazo: Baseline and 6 weeks

Active pain-free shoulder range of motion (ROM) will be assessed using a universal goniometer in four movement planes: flexion, abduction, external rotation, and internal rotation. Each movement will be measured in degrees following standardized procedures. Two consecutive measurements will be performed for each movement, and their mean will be recorded for analysis. Changes will be calculated as the week 6 measurement minus the baseline measurement, with positive values indicating improved mobility. Each movement will be analyzed separately.

Plazo: Baseline and 6 weeks

The proportion of participants achieving a clinically important improvement in shoulder pain and disability will be calculated using the change in the Shoulder Pain and Disability Index (SPADI) total score from baseline to week 6. A clinically important improvement will be defined using a prespecified threshold established in the study protocol.

Plazo: Throughout the 6-week intervention period

Adherence to the prescribed exercise program will be assessed using participant training diaries and weekly supervision records. Adherence will be calculated as the percentage of completed exercise sessions relative to the total number of prescribed sessions during the six-week intervention period.

Plazo: Throughout the 6-week intervention period

Adherence to percutaneous electrolysis will be assessed in the experimental group by recording attendance at the six scheduled treatment sessions. Adherence will be expressed as the percentage of completed electrolysis sessions relative to the six prescribed sessions.

Effects of Ultrasound-Guided Percutaneous Electrolysis Combined With Exercise Therapy Versus Exercise Therapy Alone in Patients With Chronic Supraspinatus Tendinopathy: A Randomized Controlled Trial