Abnormality
A 2026 Finnish study published in JAMA Internal Medicine that used magnetic resonance imaging (MRI) scans to look at patients’ shoulders found that 99% of Finnish adults over 40 have at least one rotator cuff abnormality.
The rotator cuff is a collection of muscles and tendons that keep the upper arm bone in the shoulder socket, and it’s complex and fiddly enough that many people experience rotator cuff injuries at some point in their lives, those injuries blamed for pain and use-related symptoms.
This study showed, however, that the vast majority of people without symptoms (no pain, no issues using their shoulder) also have rotator cuff abnormalities that are visible in MRI scans, including partial- and full-thickness tears, and tendon swelling and thickening (tendinopathy).
The implication here is that while MRI scans might be valuable in some cases for some patients, if 99% of the people scanned have rotator cuff abnormalities but most have no pain or other issues with their rotator cuff, the correlation between irregularity and problem might not be as tight as assumed, and the utility of these scans may be overstated.
There’s also a possibility that the concept of ‘abnormality’ may need to be revisited here, as something that 99% of patients have can hardly be called abnormal, and not having such issues show up on the scan is clearly the outlier.
The researchers behind this study suggest that, instead, we might consider rotator cuff tears, thickening, and swelling to be normal age-related changes—the wear-and-tear we can expect to experience as we grow older—and that might clear away some of the noise so that doctors can instead focus on truly abnormal issues that are more closely associated with pain and use-related problems.
As a side-benefit of this kind of change, patients might be less likely to assume the worst, as being told they have normal age-related changes in their shoulder would probably be a lot less worrying than being told they have abnormalities. And this could even lead to fewer unnecessary MRI scans, doctors only taking that approach when an injury clearly warrants it, and otherwise adopting a less invasive watch-and-wait stance, helping their patients regain function via rest and physical therapy.