The purpose of this study was to investigate clinical characteristics of asymptomatic rotator cuff tears. 211 of 283 shoulders diagnosed with rotator cuff tears by ultrasonography (male: 81 of 114 shoulders, female: 130 of 169 shoulders, mean age; 65.5 years old) were divided into two groups according to the presence or absence of pain: asymptomatic rotator cuff tear group (group A) and symptomatic rotator cuff tear group (group S). Age, sex, occupation, dominant arm, trauma history, impingement sign, degree of active anterior elevation, abduction strength and external rotation strength were compared between these 2 groups. Using logistic analysis, the clinical characteristics of asymptomatic rotator cuff tears were also investigated. There were 185 shoulders (65.4%) in group A, and 98 shoulders (34.6%) in group S. Although there was no significant difference in age, sex or occupation, dominant arm injury (A;51.9%, S;72.4%), positive impingement sign (A;5.9%, S;41.8%), active anterior elevation (A;150.7, S;146.1), weakness of abduction strength (A;16.8%, S;40.8%), and weakness of external rotation strength (A;12.4% S;36.7%) significantly differed. Logistic analysis showed that dominant arm (odds ratio=2.99), impingement sign (odds ratio=10.18) and external rotation strength (odds ratio=3.10) were significant. When all 3 factors were negative, 93.8% of the rotator cuff tears in this series were asymptomatic. Asymptomatic rotator cuff tear more frequently involved the non-dominant arm, was negative for impingement sign, and showed greater active anterior elevations preserved abduction strength and external rotation strength.
