Detection of subacromial bursa thickening by sonography in shoulder impingement syndrome

Background: Normally, the subacromial-subdeltoid bursa is thinner than 2 mm using ultrasound examination. The subtle thickening of the bursa could be an early sign of subacromial impingement and possibly a rotator cuff tear. The aim of this study was to compare the thickness of subacromial bursa measured using ultrasonography in the painful shoulder with normal side, and also to differentiate Neer stages I and II impingements in patients with unilateral shoulder pain. Methods: We performed bilateral shoulder sonography in 268 consecutive patients with unilateral shoulder pain and clinical suggestion of rotator cuff pathology. The study group consisted of 102 cases of Neer stage I and 166 cases of Neer stage II impingement syndrome. The bursa thickness was calculated from the superficial peribursal fat to the upper margin of the supraspinatus. Results: A statistically significant association was detected (p <.0001) between the symptomatic shoulder and asymptomatic side (mean thickness, 1.27 mm/0.75 mm). The thickness of bursa in patients with Neer stage I impingement had no statistically important link the results of the patients with Neer stage II impingement. Conclusion: Increased bursa thickness in the symptomatic side may be an alternative sonographic indicator of subacromial bursitis and partial-thickness rotator cuff tears, even when measured to be less than 2 mm. Sonographic examination of subacromial bursa thickness is not an appropriate technique to differentiate the Neer stages 1 and II impingement. Further study is needed to quantify the echogenicity of the supraspinatus tendon and to show a level of accuracy in patients with rotator cuff tendinosis or partial tears.