Patient-Specific Factors of Recovery in Rotator Cuff Tendinopathy

Patient-Specific Factors of Recovery in Rotator Cuff Tendinopathy PROJECT SUMMARY Rotator cuff tendinopathy is a frequent cause of shoulder pain. A known effective treatment is resistance exercise, which is the current standard of care. However, the outcomes of resistance exercise are highly variable, with 40-50% developing chronic or recurrent pain. Resistance exercise should be designed to stimulate tendon healing and individually tailored to change the biomarker of tendinopathy – tendon structure. The lack of knowledge as to how the tendon structure responds to resistance exercise, how this relates to patient-reported pain and disability, and what other factors impact the tendon response is limiting the delivery of patient-specific treatment approaches and outcomes of care. We hypothesize the tendon response and patient outcomes are affected by deficits in muscle function, brain pain processing, and psychological factors as they influence the ability and willingness to move the shoulder. To stimulate tendon structural remodeling, resistance exercise imparts load to the tendon via muscle activation. Deficits in shoulder muscle activation can reduce tendon loading and thus healing. Elevated pain-related psychological distress in the form of kinesiophobia and pain catastrophizing and deficits in pain and sensorimotor processing are associated with poorer outcomes and chronicity in individuals with rotator cuff tendinopathy. Our pilot work supports our hypotheses that higher levels of muscle activation along with lower levels of psychological distress, central pain and sensorimotor processing deficits are associated with a positive tendon structural response and patient outcomes. In this study, we will quantify the effects of resistance exercise on the biomarker of tendon structure and the impact of muscle deficits, psychological factors, and brain dysfunction in pain and sensorimotor processing on shoulder pain and disability outcomes. Patients with rotator cuff tendinopathy (N=70) will be observed during standard-of-care 8 weeks of a resistance exercise. At baseline, 4 weeks, 8 weeks we will use ultrasound to assess tendon structure, electromyography and a load cell for muscle, psychological factors via patient report, functional magnetic resonance brain imaging for pain and sensorimotor processing dysfunction, pain-rating during shoulder functional tasks, and shoulder functional outcomes. We will follow-up at 6-months on patient-reported shoulder outcomes. These data will deliver evidence to design and evaluate a future novel stepped and matched care pathway clinical trial; patients whose tendon is responsive to exercise will continue with resistance exercise, and those with limited response will be `stepped and matched' to alternative care of psychologically-informed treatment for brain dysfunction and psychological deficits, and/or alternative resistance approach to target muscle deficits. Resistance exercise is a known effective treatment, but not for everyone. Using the tendon structure as a marker of treatment response will aid in identifying the dose of exercise, and if other factors effect tendon effects and outcomes. Long-term, we aim to define patient-specific care pathways that can improve the delivery of care and optimize outcomes.