We have long been taught that among people fortunate enough to survive into their 80s, 70% to 80% will have a torn rotator cuff— that it’s part of life just like degenerating lumbar discs. These figures were based on cadaveric studies, a study design that comes with a whole spectrum of issues around detection and selection bias.
However, in the January 21, 2015 issue of The Journal, Keener et al. provide us with much more reliable data regarding the progression of asymptomatic rotator cuff tears in a population of 224 subjects. The cohort included people with an asymptomatic rotator cuff tear in one shoulder and pain due to rotator cuff disease in the contralateral shoulder. As determined by ultrasound, 118 had full thickness tears, and 56 had partial thickness tears. Importantly, the study also included 50 controls with no ultrasound evidence of rotator cuff tear in one shoulder and painful cuff disease in the contralateral shoulder. Researchers followed the cohort for a mean of more than 5 years.
The good news is that neither age nor gender was found to be related to the risk of tear enlargement. Tear enlargement occurred in 49% of all the shoulders at a median of 2.8 years, and the risk of enlargement was 4.2 times and 1.5 times higher in subjects with full thickness tears, relative to controls and those with partial thickness tears, respectively. Both tear type and tear enlargement were associated with the onset of “new pain,” further assuring us that following our rotator cuff patients clinically is a sound and cost-efficient strategy.
What I found most interesting is that progressive muscular degeneration in the supraspinatus muscle belly, as detected by ultrasound, was associated with tear enlargement. This strengthens our recommendations—to our patients and ourselves—to engage in rotator cuff strengthening as a part of overall resistance training for lifelong maintenance of function and preservation of muscle mass.
So…. to protect our cuff integrity and for innumerable other reasons, back to the gym we go.
Marc Swiontkowski, MD