Objective: Coracoid impingement has been recognized as an etiology for anterior shoulder pain; however, no imaging reference standard exists. We used sonography to compare the coracohumeral interval (CHI) in asymptomatic volunteers with the CHI in patients with coracoid impingement.
Methods: Bilateral shoulder sonography was performed in 19 asymptomatic volunteers (10 men and 9 women) and in 8 shoulders in 7 patients (6 men and 1 woman) with a clinical diagnosis of coracoid impingement. With the arm adducted across the chest, the interval between the coracoid process and the lesser tuberosity of the humerus was measured using a linear array ultrasound transducer with a peak frequency of 13 MHz.
Results: In the asymptomatic volunteers, the mean +/- SD for the CHI was 12.2 +/- 2.5 mm (range, 7.8-17.5 mm). In the symptomatic shoulders, the mean +/- SD for the CHI was 7.9 +/- 1.4 mm (range, 5.9-9.6 mm). Repeated measures analysis of variance revealed the CHI to be significantly narrower in symptomatic shoulders than in asymptomatic volunteers (P < .0001).
Conclusions: These data suggest a role for sonography in diagnosing coracoid impingement.