Active vs. sham pulsed electromagnetic field therapy added to standardized conservative care for partial-thickness supraspinatus tears: study protocol for a randomized, assessor-blinded, sham-controlled trial.

Background: Partial-thickness supraspinatus tears commonly cause shoulder pain and functional limitation. Although conservative treatment can improve symptoms, whether pulsed electromagnetic field (PEMF) therapy provides additional clinically meaningful benefit remains uncertain. Existing PEMF evidence is mainly derived from rotator cuff tendinopathy or subacromial impingement populations, whereas sham-controlled evidence in MRI-confirmed partial-thickness supraspinatus tears remains sparse. Methods: This is a single-center, parallel-group, randomized, assessor-blinded, sham-controlled trial. Fifty adults with symptomatic MRI-confirmed partial-thickness supraspinatus tears and baseline activity-related shoulder pain of at least 3 cm on a 10-cm Visual Analog Scale (VAS) will be recruited at Yibin Hospital of Traditional Chinese Medicine and randomized 1:1 to active PEMF plus standardized conservative care or sham PEMF plus identical standardized conservative care. Standardized conservative care includes oral nonsteroidal anti-inflammatory drugs when indicated, low-frequency pulsed electrical stimulation, activity modification, and a structured home exercise program. Active PEMF will be delivered using the YS2002 device (30 mT, 40 Hz) for 20 min once daily for 4 weeks; the sham procedure will be identical in appearance, treatment schedule, indicator lights/sounds, heat, vibration, and staff interaction but will not deliver an effective electromagnetic field. The randomized contrast therefore isolates the electromagnetic-field component of the YS2002 platform, because all other conservative-care elements, heat/vibration settings, and staff interactions will be standardized in both groups. Outcomes will be assessed at baseline, Week 4, and at 3, 6, and 12 months. The primary outcome is the between-group difference in Constant-Murley Score at Week 4 adjusted for baseline score, defined as an early clinical functional endpoint rather than a measure of structural tendon healing. Secondary outcomes include pain, range of motion, Shoulder Pain and Disability Index, MRI structural outcomes at 6 months, adverse events, adherence, and additional shoulder-related interventions during follow-up. Discussion: This trial will provide sham-controlled evidence on whether active electromagnetic-field delivery provides additional short-term symptomatic and functional benefit and acceptable safety when added to a standardized conservative-care package for symptomatic partial-thickness supraspinatus tears. The 6-month MRI outcomes and longer-term clinical outcomes will be interpreted as exploratory signals to inform future multicenter trials rather than definitive evidence of biological repair.