Chronic shoulder pain, specifically stemming from subacromial impingement syndrome (SAIS), remains one of the most persistent musculoskeletal challenges in orthopaedic rehabilitation. As clinicians, we frequently encounter patients who have failed conservative management or whose progress has plateaued. This clinical reality often drives the search for multimodal treatment adjuncts—such as peripheral nerve stimulation—to enhance the efficacy of standard exercise protocols. However, a recent high-quality Randomized Controlled Trial (RCT) published in the American Journal of Physical Medicine & Rehabilitation brings critical evidence to the conversation regarding the necessity of axillary motor stimulation.
Investigating Adjuncts for Chronic Shoulder Pain
The premise of using motor stimulation is physiologically sound: by stimulating the axillary nerve, clinicians aim to improve deltoid activation, potentially correcting glenohumeral mechanics and reducing subacromial compression during elevation. To test this hypothesis, Pierson et al. (2026) conducted a rigorous, dual-site, randomized, participant- and assessor-blinded, placebo-controlled trial. The objective was clear: determine if adding axillary motor stimulation to a standardized physical therapy program offers superior outcomes compared to physical therapy alone.
Study Design and Methodology
The research team recruited 116 participants suffering from chronic shoulder pain attributed to SAIS. The cohort was randomized 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 no-stimulation control (placebo).
Primary outcomes focused on the "worst pain in the past week" using the Brief Pain Inventory (Short Form). Secondary measures were comprehensive, including the Shoulder Pain and Disability Index (SPADI), the Functional Assessment Test, and the Short-Form 36 health survey.
Clinical Outcomes: The Power of Standardized Protocols
The results of this 2026 study provide a reassuring validation of exercise-based rehabilitation. Both groups demonstrated statistically significant improvements over time across all assessed outcome measures. Whether measuring pain reduction, functional range of motion, or quality of life, the participants improved.
However, the comparison between the groups revealed the critical clinical takeaway: there was no significant difference between the group receiving motor stimulation and the group receiving physical therapy alone. The addition of the electrical modality did not accelerate recovery or result in lower pain scores compared to the standardized exercise protocol.
Implications for Physiotherapy Practice
For the orthopaedic manual therapist and physiotherapist, these findings are highly relevant. While "no significant difference" can sometimes be viewed as a negative result, in this context, it is positive for resource management. The data suggests that standardized physical therapy—likely consisting of rotator cuff strengthening, scapular stabilization, and mobility work—is the primary driver of recovery in chronic SAIS.
While axillary motor stimulation was found to be safe (no adverse events were recorded) and efficacious as part of a package, it does not appear to be an essential component for success. Clinicians can confidently focus on optimizing exercise compliance and load management, knowing that physical therapy alone is sufficient for significant functional gains in this 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.
