The majority of rotator cuff tears is asymptomatic {1}. What makes a rotator cuff tear symptomatic or asymptomatic in humans?
References:
{1} Minagawa, Hiroshi, Nobuyuki Yamamoto, Hidekazu Abe, Masashi Fukuda, Nobutoshi Seki, Kazuma Kikuchi, Hiroaki Kijima, and Eiji Itoi. "Prevalence of symptomatic and asymptomatic rotator cuff tears in the general population: from mass-screening in one village." Journal of orthopaedics 10, no. 1 (2013): 8-12. https://scholar.google.com/scholar?cluster=6848408356619886538&hl=en&as_sdt=0,22 ; https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3768248/
In conclusion, our survey of 664 residents in one village demonstrated that the prevalence of rotator cuff tear was 22.1% in the general population, which increased with age. Asymptomatic tear was twice as common as symptomatic tear.
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In this study, “asymptomatic” was defined as having neither pain nor any other symptoms related to the shoulder when the survey was conducted including the past history of shoulder pain, whereas “symptomatic” was defined as having pain or any other symptoms related to the shoulder when the survey was conducted.
Caption: Prevalence of symptomatic and asymptomatic tears. Asymptomatic tear accounted for 50% of all tears in the 50s. However, in the 60s and over, the percentage of asymptomatic tear was significantly greater than that of symptomatic tear.