Contrast-enhanced ultrasound characterization of the vascularity of the rotator cuff tendon: Age- and activity-related changes in the intact asymptomatic rotator cuff
The natural history of the blood supply to the rotator cuff and its role in the etiology of rotator cuff disease has not been definitively established. To date, there has not been an in-vivo dynamic assessment of the baseline vascularity of the asymptomatic rotator cuff. This study was designed to test the hypothesis that regional variations in supraspinatus tendon vascularity exist with an age-dependent decrease in asymptomatic individuals with intact rotator cuffs. Lipid microsphere, contrast-enhanced ultrasound shoulder examinations were done in 31 patients with a mean age of 41.5 years (range, 22-65 years). Images were obtained at baseline, after contrast administration at rest, and after contrast administration following exercise to visualize the intratendinous blood flow to the supraspinatus tendon. Qualitative and quantitative analysis was performed by determining 4 regions of interest (bursal medial, articular medial, bursal lateral, and articular lateral) with quantification and analysis software (QLAB Philips, Andover, MA) to examine each region of interest and normalize data for interpretation of the mean intensity per pixel. A statistically significant decrease in blood flow to the supraspinatus tendon with age was observed in a comparative analysis of patients aged younger than 40 and older than 40, (P < .05 for all 4 zones after exercise and for the bursal medial, articular medial, and bursal lateral zones after exercise; P = .07 for the articular lateral zone after exercise). A statistically significant increase in blood flow with exercise was observed in an analysis of all patients (P < .001). The age-related decrease in the vascular supply of the tendon observed in this study is consistent with published reports demonstrating an increasing prevalence of rotator cuff pathology with age and may predispose to the development of rotator cuff tendinopathy and, ultimately, attritional tears.