Is supraspinatus pathology as defined by magnetic resonance imaging associated with clinical sign of shoulder impingement?

To examine the association between supraspinatus pathology and clinical sign of impingement, 42 workers with and 31 age-matched workers without signs of subacromial impingement had their shoulder examined by magnetic resonance imaging. All subjects were selected from an epidemiologic study evaluating the risk of shoulder impingement syndrome in relation to ergonomic exposure. Physical examination was conducted according to the same protocol and included assessment of shoulder function. Magnetic resonance images were evaluated in a blinded manner with regard to clinical status and age. Twenty-two (55%) subjects in the impingement group and 16 (52%) subjects in the control group had a pathologic supraspinatus tendon (odds ratio 1.13 [95% confidence interval 0.45 to 2.88]). The prevalence of supraspinatus pathology increased from 32% in the youngest to 48% in the middle and 72% in the oldest age group. The results of this study indicate that supraspinatus pathology is related to age rather than to clinical sign of impingement.