Qualitative analysis of the supraspinatus muscle fatty infiltration on MRI: correlation of the tangent sign with Goutallier grade at the Y view and medial scapular border in large retracted rotator cuff tears

Background: Surgically repairing rotator cuff tears with a higher extent of fatty infiltration (FI) is controversial. Current evidence sup- ports performing rotator cuff repair in patients exhibiting Goutallier stage 3-4 FI. However, the presence of retraction complicates ac- curate assessment using the Goutallier Classification, particularly on the lateral Y-view. A shift toward classifying FI in more medial regions may enhance the precision of tissue quality quantification. The objective of this study was to analyze the uniformity of FI within the entire supraspinatus muscle using the Goutallier Classification across 3 scapular Y-view sections and to examine the association between Goutallier grade, tangent sign, and modified Patte stage. Methods: A retrospective evaluation was conducted on preoperative magnetic resonance imaging scans from a consecutive series of 97 patients who had previously undergone arthroscopic rotator cuff repairs. Three supraspinatus sections on the magnetic resonance imaging sagittal plane were identified: the lateral Y-view (section 1), a medial section at the suprascapular notch anatomical landmark (section 2), and a section 3 cm medial from the suprascapular notch Medial Scapular Body (section 3). Goutallier grade, tangent sign, and modified Patte stage were used to evaluate FI, muscle atrophy, and tendon retraction, respectively. Results: Section 1 had the highest Goutallier grade, while section 3 had the lowest. Intraobserver rest retest reliability analysis showed excellent consistency in all sections with section 2 (intraclass correlation coefficient [ICC] = 0.920, 95% confidence interval [CI]), sec- tion 2 (ICC = 0.917, 95% CI), and section 3 (ICC = 0.923, 95% CI) for Goutallier grade. Interobserver reliability analysis also revealed excellent consistency in section 1 (ICC = 0.951, 95% CI), section 2 (ICC = 0.949, 95% CI), and section 3 (ICC = 0.922, 95% CI) for Goutallier grade. A strong correlation was observed between Goutallier grade and modified Patte stage (tb = 0.43-0.56, P = .001), and between Goutallier grade and tangent sign (tb = 0.43-0.54, P = .001) across all sections. Conclusion: The severity of FI within the supraspinatus muscle belly is inconsistent, with the lateral portion being the most severe and the medial portion the least severe. Goutallier grade demonstrates a strong correlation with tangent sign and modified Patte stage. This suggests that tendon retraction results in a potential overestimation in the amount of FI defining some tears unjustly irreparable when measuring at the traditionally described lateral Y-view position compared with 3 cm medial. Level of evidence: Anatomy Study; Imaging (c) 2024 The Author(s). This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).