Study seeks to understand why the same shoulder injury can cause serious pain in some patients and no symptoms in others

By Jill Pease

Dr. Federico Pozzi
Dr. Federico Pozzi

Rotator cuff tears are one of the most common causes of shoulder pain and disability, but improvements in treatment outcomes for this injury have been stubbornly slow. A new University of Florida College of Public Health and Health Professions study is designed to advance treatment options by investigating the central nervous system’s role in how people with rotator cuff tears perceive pain.

The study is supported by a five-year grant from the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health.

Rotator cuff tears are responsible for millions of Americans seeking treatment every year, yet some people with the injury don’t ever experience symptoms. The reason why some people with rotator cuff tears have debilitating pain and some people feel nothing is the million dollar question, said the new study’s lead investigator Federico Pozzi, Ph.D., P.T., an assistant professor in the UF PHHP department of physical therapy.

“Rotator cuff tears can impact patients very differently,” Pozzi said. “A good number of individuals older than 50 may have a rotator cuff tear and do not know about it because they do not have symptoms. On the other hand, individuals with symptomatic rotator cuff tears often report pain and loss of arm function, with difficulty completing activities of daily living or job duties.”

The variation in patient experience with rotator cuff tears suggests that there is more at work than structural injury to the shoulder.

“Our central hypothesis is that the nervous system plays a larger role in symptom severity and recovery than conventionally believed,” Pozzi said.

Previous research in other chronic musculoskeletal conditions points to differences in the way patients process pain, but until now, these studies have not examined rotator cuff tears. This has hindered clinicians’ ability to design targeted treatments for their patients, Pozzi said.

For the new study, Pozzi and UF colleagues will evaluate participants with both painful and asymptomatic rotator cuff tears using functional brain imaging while participants perform specific movements. Using the data they obtain on pain phenotypes, symptoms and brain function, the team will test models to predict patients’ treatment outcomes.

“Our study will build the foundational knowledge to improve the current management of rotator cuff tears and identify additional factors that may influence the variability in patient outcomes,” Pozzi said.

In addition to Pozzi, the study team includes UF investigators Mark Bishop, P.T. Ph.D., an associate professor of physical therapy; Stephen Coombes, Ph.D., an associate professor of applied physiology and kinesiology; Kevin Farmer, M.D., a professor of orthopaedic surgery and sports medicine; Subharup Guha, Ph.D., an associate professor of biostatistics; Kimberly Sibille, Ph.D., an associate professor in the departments of physical medicine & rehabilitation and anesthesiology; and Jared Tanner, Ph.D., a research assistant professor of clinical and health psychology.