The Challenge of Chronic Subacromial Pain
Chronic shoulder pain, particularly stemming from subacromial impingement syndrome (SAIS), remains one of the most persistent musculoskeletal complaints encountered in outpatient orthopedic clinics. For physiotherapists, the management of SAIS often involves a multimodal approach, combining manual therapy, therapeutic exercise, and occasionally, electrophysical agents. While the efficacy of therapeutic exercise is well-established, the search for adjunct therapies that can enhance motor recruitment and pain modulation continues. One such emerging intervention is peripheral motor stimulation.
Specifically, axillary motor stimulation has been theorized to enhance the efficacy of traditional physical therapy by potentially improving deltoid and rotator cuff recruitment patterns or providing neuromodulatory pain relief. However, does the addition of this technology yield statistically significant benefits over a robust, standardized physical therapy protocol alone? A recent randomized controlled trial by Pierson et al. (2026) sought to answer this question.
Investigating Axillary Motor Stimulation
The study, published in the American Journal of Physical Medicine & Rehabilitation, utilized a rigorous dual-site, randomized, participant- and assessor-blinded, placebo-controlled design. The researchers recruited 116 participants suffering from chronic shoulder pain attributed to subacromial impingement syndrome.
The cohort was divided into two distinct groups:
- Intervention Group (n=60): Received standardized physical therapy combined with active axillary motor stimulation.
- Control Group (n=56): Received the same standardized physical therapy protocol combined with a sham (no stimulation) intervention.
The primary outcome measure tracked was the “worst pain in the past week” using the Brief Pain Inventory (Short Form). Secondary measures included the Shoulder Pain and Disability Index (SPADI), functional assessment tests, and the Short-Form 36 health survey. This comprehensive array of metrics allowed the authors to evaluate not just pain intensity, but also functional capacity and quality of life.
Outcomes: The Power of Standardized Protocols
The results of the trial offer a validating, albeit nuanced, message for the physiotherapy profession. Both groups demonstrated significant improvements over time across all assessed outcome measures. Whether the patient received the active motor stimulation or the sham, their pain decreased, and their function improved significantly.
Crucially, however, the statistical analysis revealed no significant difference between the two groups. The addition of axillary motor stimulation did not provide a superior clinical outcome compared to physical therapy alone. This suggests that the standardized physical therapy protocol—likely consisting of rotator cuff strengthening, scapular stabilization, and mobility work—was the primary driver of recovery.
Clinical Implications for Therapists
For the practicing clinician, these findings are highly relevant. While neuromuscular electrical stimulation (NMES) and other motor stimulation modalities have their place in rehabilitation—particularly for muscle re-education post-surgery—their utility in chronic SAIS may be limited when a patient is capable of completing a structured exercise program.
The study concludes that while physical therapy plus motor stimulation is efficacious, physical therapy alone is sufficient. This reinforces the value of active rehabilitation. Clinicians should feel confident that adhering to evidence-based, standardized exercise protocols is the most critical factor in resolving chronic subacromial pain. Time and resources may be better spent ensuring patient adherence to exercise rather than applying passive adjuncts that do not demonstrate added value in this specific population.
References
Pierson, C. J., Jain, N. B., Hansen, K., Hisel, T. Z., Frost, S. K., Whitehair, V. C., Konda, C., DeVahl, J. M., Van Acker, G., DiLorenzo, D. R., Chae, J., Gunzler, D. D., Kim, C. H., & Wilson, R. D. (2026). Efficacy of Standardized Physical Therapy and Axillary Motor Stimulation for Chronic Shoulder Pain: A Randomized Controlled Trial. American Journal of Physical Medicine & Rehabilitation. https://pubmed.ncbi.nlm.nih.gov/41707131/
