The Search for Adjuncts in Shoulder Rehabilitation
Chronic shoulder pain, specifically stemming from subacromial impingement syndrome (SAIS), remains one of the most prevalent and persistent musculoskeletal complaints treated in orthopedic clinics. While exercise therapy remains the gold standard, clinicians frequently seek multimodal approaches to enhance outcomes, improve recruitment, and manage pain. Neuromuscular electrical stimulation and motor stimulation are often utilized as adjuncts to facilitate muscle activation patterns in the rotator cuff and deltoid complex. However, does the addition of specific axillary motor stimulation (AMS) provide a statistically significant benefit over standardized physical therapy alone?
A recent 2026 randomized controlled trial by Pierson et al., published in the American Journal of Physical Medicine & Rehabilitation, sought to answer this question. The study aimed to isolate the efficacy of AMS when combined with a standardized protocol, providing crucial data for evidence-based practice regarding resource allocation and treatment time.
Investigating the Efficacy of Motor Stimulation
The research team designed a robust dual-site, randomized, participant and assessor-blinded, placebo-controlled trial involving 116 participants. All subjects presented with chronic shoulder pain attributed to subacromial impingement syndrome. To evaluate the specific contribution of the modality, participants were randomized into two distinct groups:
- Intervention Group (n=60): Received standardized physical therapy plus active axillary motor stimulation.
- Control Group (n=56): Received standardized physical therapy plus a placebo (no stimulation).
The primary outcome measure tracked was the “worst pain in the past week” using the Brief Pain Inventory (Short Form). Secondary measures provided a comprehensive view of recovery, utilizing the Shoulder Pain and Disability Index (SPADI), the Functional Assessment Test for the upper extremity, and the Short-Form 36 (SF-36) for quality of life metrics.
Standardized Therapy Drives Outcomes
The results of the trial highlight the intrinsic value of structured exercise prescription. Both groups demonstrated statistically significant improvements over time across all assessed outcome measures. Whether the patients received the active motor stimulation or the placebo, their pain scores dropped, and their functional scores (SPADI and functional assessment tests) improved.
Crucially, the statistical analysis revealed no significant difference between the two groups. The addition of axillary motor stimulation did not accelerate recovery or result in lower pain scores compared to the group that received physical therapy alone. Furthermore, the safety profile was excellent, with no significant adverse events related to the interventions observed in either cohort.
Implications for Clinical Practice
For the practicing physiotherapist, these findings reinforce the primacy of active rehabilitation. While AMS is safe and “efficacious” in the sense that the treatment group improved, the improvement appears to be driven by the standardized physical therapy component rather than the stimulation itself.
This evidence suggests that while motor stimulation is not harmful, it may be an unnecessary expenditure of clinical time and financial resources if a patient is capable of completing a standardized exercise protocol. The data validates that a well-structured, exercise-based approach is sufficient for managing chronic subacromial impingement syndrome effectively. Clinicians can confidently focus on adherence to exercise and load management, knowing that omitting axillary motor stimulation does not compromise the patient’s potential for recovery.
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/
