Introduction: Little comparative information is available regarding asymptomatic and symptomatic rotator cuff tears. This data may lend insight to Natural History. The purpose of this study was to compare the morphology and incidence of cuff disease in people with unilateral painful shoulders.

Methods: 588 consecutive shoulder ultrasounds were reviewed in patients presenting with unilateral pain. Ultrasound has been validated in our institution as highly accurate. There were 212 pt/bilat intact cuffs, 191pt/unilateral tears, and 185pt/bilateral tears. Data for age, cuff thickness, tear size, and symptoms were tested for associations.

Results: Cuff disease increased with average age, (no tear/48.7yo,unilateral tear/58.7yo,bilateral tears/67.8yo). Logistic regression showed a 50% likelihood of bilateral tears after age 66(p< .01). Overall, a pt. with a full tear on the symptomatic side had a 35.5% incidence of an asymptomatic tear. In contrast, a symptomatic nl. or partial tears had only a 0.5% or 4.3% incidence of contralateral tear. In patients with bilateral tears, the symptomatic side was larger (p< .01). 65% of painful tears were on the dominant side(p< .01). For intact cuffs, avg thickness equaled 4.7 mm and was not affected by age, gender, or symptoms.

SUMMARY: The high incidence of asymptomatic and bilateral tears with age suggests that for some, cuff disease is intrinsic; however, the association with symptoms of hand dominance and increased tear size indicate that extrinsic factors may be important in the development of pain.