Therapeutic Exercise for Rotator Cuff Tendinopathy / Subacromial Pain Syndrome - Outcomes and Mechanisms

Mechanisms of Exercise for Rotator Cuff Tendinopathy / Subacromial Pain Syndrome

Rotator cuff tendinopathy, one of the pathologies identified as part of the cluster of shoulder symptoms known as subacromial pain syndrome, is a common musculoskeletal shoulder condition. Resolution of pain and disability is poor despite treatment, with only about 50% reporting full recovery at 12 - 18 months. Prior studies suggest therapeutic exercise when used alone and with other interventions can have positive outcomes; however, not all patients with rotator cuff tendinopathy respond. Few studies have assessed the effects of exercise for individuals with chronic pain, especially brain driven mechanisms, thought to play a key role. In this study, we will use brain imaging to understand the mechanisms, identify predictors of a positive response to exercise, and the relationship to biomechanical and pain-related factors in patients with RC tendinopathy. The findings from this study will optimize the delivery and treatment response to exercise for individuals with shoulder pain.

Theoretical models propose the development of shoulder pain from an acute injury or repetitive motion seen in sports and certain work environments. Repetitive motions, in combination with altered muscle activity and altered movement strategies, may lead to damage of the rotator cuff structures resulting in local shoulder pain. Emerging evidence supports the hypothesis that localized pain may result in chronic centralized pain over time through central sensitization. Central nervous system changes, specifically those at the level of the brain have been shown to play a role in chronic pain. Neurophysiological mechanisms have been shown to predict symptom progression in other chronic pain conditions. Despite a large body of evidence that therapeutic exercise, mechanisms leading to pain relief are still not well understood. Studies identify a critical role of exercise in modulating excitation and inhibition of key pain centers in the central nervous systems. However, limited evidence exists as to the mechanisms of exercise in the management of patients with chronic pain with therapeutic exercise.

Inclusion Criteria:

1. the clinical diagnosis for RC tendinopathy will be made with positive 3 of 5 tests: Hawkins-Kennedy, Neer, painful arc, empty can, external rotation resistance test
2. pain ≥ 3/10 on a numeric pain rating scale
3. age: 18 - 45 years
4. Participant must read, sign and date the appropriate Informed consent document.
5. Participant BMI ≤ 30

Exclusion Criteria:

1. Insufficient ability to comprehend and complete the questionnaires,
2. Inability to attend sessions,
3. Prior surgery of shoulder, neck or thoracic spine,
4. Primary complaint of neck or thoracic pain,
5. Diagnosis of cervical spinal stenosis,
6. Any serious spinal and shoulder pathology: infections, arthrosis, rheumatic disorders, acute fractures, shoulder dislocation, osteoporosis, or tumors,
7. Central Nervous System involvement, to include hyperreflexia, sensory disturbances in the hand, intrinsic muscle wasting of the hands, unsteadiness during walking, nystagmus, loss of visual acuity, impaired sensation of the face, altered taste, the presence of pathological reflexes (i.e. positive Hoffman and/or Babinski reflexes,
8. two or more neurologic signs of nerve root compression to include myotomal weakness, positive muscle stretch reflex, and dermatomal sensory loss,
9. any shoulder or arm pain with cervical spine tests of Spurling's Test, cervical rotation to the ipsilateral side, or axial compression test, or
10. primary adhesive capsulitis defined by passive range of motion loss >50% as compared bilaterally of shoulder external rotation, internal rotation, or elevation.
11. Has a device or other condition that is not safe for MRI, including pacemakers.