Hypothesis and background: Abnormalities of the rotator cuff are more common with age, but the exact prevalence of abnormalities and the extent to which the presence of an abnormality is associated with symptoms are topics of debate. Our aim was to review the published literature to establish the prevalence of abnormalities of the rotator cuff and to determine if the prevalence of abnormalities increases with older age in 10-year intervals. In addition, we assessed prevalence in 4 separate groups: (1) asymptomatic patients, (2) general population, (3) symptomatic patients, and (4) patients after shoulder dislocation.
Methods: We searched PubMed, EMBASE, and the Cochrane Library up to February 24, 2014, and included studies reporting rotator cuff abnormalities by age. Thirty studies including 6112 shoulders met our criteria. We pooled the individual patient data and calculated proportions of patients with and without abnormalities per decade (range, younger than 20 years to 80 years and older).
Results: Overall prevalence of abnormalities increased with age, from 9.7% (29 of 299) in patients aged 20 years and younger to 62% (166 of 268) in patients aged 80 years and older (P < .001) (odds ratio, 15; 95% confidence interval, 9.6-24; P < .001). There was a similar increasing prevalence of abnormalities regardless of symptoms or shoulder dislocation.
Discussion and conclusion: The prevalence of rotator cuff abnormalities in asymptomatic people is high enough for degeneration of the rotator cuff to be considered a common aspect of normal human aging and to make it difficult to determine when an abnormality is new (e.g., after a dislocation) or is the cause of symptoms.