A new method of the dynamic assessment of the supraspinatus using ultrasonography

We devised a new dynamic assessment of the supraspinatus (DAS) using ultrasonography. The objectives of this study are as follows: 1. to verify the moving distance of the supraspinatus using ultrasonography in the cadaveric shoulders; 2. to evaluate the reliability of DAS in patients with rotator cuff tear (RCT) and investigate the correlation between DAS and magnetic resonance imaging (MRI) assessments. In Part 1, the supraspinatus in both shoulders of one cadaveric specimen was pulled laterally by 5 mm and 10 mm. In the ultrasonographic movie of the supraspinatus, the moving distances of a placed marker and a representative speckle which was visually identified as a high-intensity dot with the longest track were measured. In Part 2, among 62 RCT shoulders we verified the interrater agreement of DAS and correlation between DAS and MRI findings of RCT size and muscle atrophy. In Part 1, during the supraspinatus traction, the moving distances of the marker and speckle were almost same; 1.07–2.68 mm and 1.60–2.67 mm, respectively (the pulled distance was 5 mm), 3.95–5.35 mm and 3.59–5.60 mm (the pulled distance was 10 mm). In Part 2, DAS showed a high interrater agreement of 0.74 in the kappa coefficients. DAS showed no correlations with tear size and atrophy, respectively (Spearman's rank correlation coefficient (ρ): 0.14 (p = 0.35) and 0.13 (p = 0.29)). DAS can reliably demonstrate dynamic aspects of the supraspinatus in RCT patients, which have been lacked in static imaging assessments as MRI.