Clinical application of musculoskeletal for supraspinatus tendon tears with fat infiltration

There is a relative scarcity of studies focusing on fat infiltration in the supraspinatus muscle using musculoskeletal ultrasound (MSK US). This study aimed to investigate the clinical application value of MSK US in assessing fat infiltration of the supraspinatus muscle in patients with supraspinatus tendon tears.

We conducted a retrospective analysis of 154 patients diagnosed with supraspinatus tendon tears by arthroscopy. All patients underwent semi-quantitative grading of supraspinatus muscle fat infiltration using MSK US, complemented by shear wave elastography (SWE). Magnetic resonance imaging (MRI) served as the gold standard. Diagnostic performance metrics were calculated for MSK US in detecting fat infiltration, and Kappa consistency analysis was assessed between MSK US and MRI findings. Additionally, Spearman correlation analysis was performed to evaluate the relationship between the degree of fat infiltration quantified by MSK US and the extent of supraspinatus tendon tear as determined arthroscopically.

Arthroscopic results revealed full-thickness tears in 50 patients (32.47%, 50/154), and partial tears in 104 patients (67.53%, 104/154). In terms of tear grades by arthroscopy, 22 cases were Grade I (14.29%, 22/154), 38 were Grade II (24.68%, 38/154), and 94 were Grade III (61.04%, 94/154). The SWE measurements demonstrated significantly lower shear wave velocity in the affected supraspinatus muscle (2.52±0.56 cm/s) compared with the healthy side (3.03±0.64 cm/s; t=7.42, P<0.001). Using MRI as a reference standard, MSK US achieved a sensitivity of 94.90%, specificity of 82.14%, positive predictive value of 90.29%, negative predictive value of 90.20%, accuracy rate of 90.26%, and an area under the receiver operating characteristic (ROC) curve of 0.89. A statistically significant positive correlation was observed between the degree of supraspinatus muscle fat infiltration assessed by MSK US and the extent of supraspinatus tendon tear determined arthroscopically (rs=0.47, P<0.001).

The fat infiltration in the supraspinatus muscle, as assessed by MSK US, demonstrated moderate consistency with MRI diagnoses, underscoring its high clinical value. A strong association was observed between supraspinatus muscle fat infiltration and the severity of supraspinatus tendon tears. Specifically, higher-grade tendon tears were significantly correlated with greater degrees of fat infiltration within the supraspinatus muscle.