The concept that a structural change such as a rotator cuff tear seen on MRI is causing pain is ingrained in modern medical thought. Doctors and patients alike believe this, but the validity of the concept is questionable. A recent shoulder study that shows that pain associated with a torn rotator cuff doesn’t depend on the size of the tear, but instead on the levels of a nasty inflammatory cytokine that’s invisible on MRI.

Patients are conditioned by their doctors to believe that what’s seen on a shoulder MRI explains their pain. Doctors who know better can find it frustrating to attempt to convince their patients otherwise. Yet one study after another continues to show that shoulder MRI results often can’t pinpoint why a patient is experiencing pain. What does explain the pain? It turns out that pain may have much more to do with invisible chemicals than with structural damage visible on MRI.

On April 30, 2015, the International Journal of Rheumatic Diseases reported results of a Japanese study in which joint fluid was obtained from 38 patients before and after orthopedic rotator-cuff surgery. The fluid then was analyzed using enzyme-linked immuno-sorbent assay (ELISA) testing for various chemical messenger molecules called cytokines. Results indicated that larger rotator-cuff tears were associated with less pain. On the other hand, more pain was reported by patients whose joint fluid showed an increase of IL-8 (an inflammatory cytokine).

Although many physicians believe deeply that what is seen on a shoulder MRI is what’s causing their patient’s pain, there’s scant supporting evidence for this widely held belief. In reality, shoulder pain associated with a torn rotator cuff appears to be determined by a chemical that’s invisible on MRI. It’s time for doctors to abandon the myth that all structural damage seen on MRI equals pain, a false belief that leads to vast numbers of unnecessary shoulder surgeries every year.

“Shoulder Rotator Cuff MRI and IL-8: Yes Virginia There is a Santa Claus?” first appeared as a post on the Regenexx blog.