Elasticity of torn supraspinatus tendons measured by shear wave elastography: a potential surrogate marker of chronicity?

Purpose: This study investigated whether shear wave elastography (SWE) could be used to estimate the chronicity of supraspinatus tendon (SST) tears. Methods: A retrospective study was performed. From November 2015 to July 2016, 113 patients (52 men, 61 women; age range, 21 to 79 years) with persistent shoulder pain underwent 119 rotator cuff tendon examinations by routine B-mode ultrasonography, while SST elasticity was measured using SWE. Following the exclusion of eight suboptimal examinations, four examinations with missing SST measurements, and 27 examinations of patients with other conditions, 80 examinations were analyzed. A torn SST was found in 54 examinations (27 with a partial-thickness tear and 27 with a full-thickness tear). Elasticity values were compared in multiple ways. The results were analyzed using the Mann-Whitney U test or Kruskal-Wallis test. Results: No statistically significant difference in elasticity values (in kPa) was found between normal (median, 94.65; interquartile range [IQR], 87.43 to 105.47) and torn SSTs (median, 96.79; IQR, 86.71 to 108.56) or between full-thickness tears (median, 93.80; IQR, 82.50 to 108.33) and partial-thickness tears (median, 96.83; IQR, 90.60 to 112.20). However, there was a statistically significant difference in elasticity according to whether the duration of symptoms was 1 year or less (median, 92.20; IQR, 84.01 to 104.38) or longer than 1 year (median, 105.10; IQR, 100.41 to 116.03; P=0.032). Conclusion: Elasticity values were significantly higher in torn SSTs in patients with chronic shoulder pain that had persisted for more than 1 year. Further studies with larger samples seem warranted to determine whether elasticity values measured by SWE can be used preoperatively as a surrogate marker of the chronicity of a rotator cuff tendon tear.