Effects of Adding Interferential Therapy Electro-Massage to Usual Care after Surgery in Subacromial Pain Syndrome: A Randomized Clinical Trial

Subacromial pain syndrome (SAPS) is a prevalent condition that results in loss of function. Surgery is indicated when pain and functional limitations persist after conservative measures, with scarce evidence about the most-appropriate post-operative approach. Interferential therapy (IFT), as a supplement to other interventions, has shown to relieve musculoskeletal pain. The study aim was to investigate the effects of adding IFT electro-massage to usual care after surgery in adults with SAPS. A randomized, single-blinded, controlled trial was carried out. Fifty-six adults with SAPS, who underwent acromioplasty in the previous 12 weeks, were equally distributed into an IFT electro-massage group or a control group. All participants underwent a two-week intervention (three times per week). The control group received usual care (thermotherapy, therapeutic exercise, manual therapy, and ultrasound). For participants in the IFT electro-massage group, a 15-min IFT electro-massage was added to usual care in every session. Shoulder pain intensity was assessed with a 100-mm visual analogue scale. Secondary measures included upper limb functionality (Constant-Murley score), and pain-free passive range of movement. A blinded evaluator collected outcomes at baseline and after the last treatment session. The ANOVA revealed a significant group effect, for those who received IFT electro-massage, for improvements in pain intensity, upper limb function, and shoulder flexion, abduction, internal and external rotation (all, p < 0.01). There were no between-group differences for shoulder extension (p = 0.531) and adduction (p = 0.340). Adding IFT electro-massage to usual care, including manual therapy and exercises, revealed greater positive effects on pain, upper limb function, and mobility in adults with SAPS after acromioplasty.