The impact of supraspinatus tear on subscapularis muscle atrophy and fatty infiltration

Abstract

Background: Aimed to report the prevalence and predisposing factors affecting subscapularis muscle atrophy and fatty infiltration (MAFI) in patients without a subscapularis tear, and to analyze the effect of this condition on surgical outcomes.

Methods: Between 2020 and 2022, 153 patients (mean age 58.1 ± 10.2 years; 84 men and 69 women) who underwent repair of posterosuperior cuff tears, with no subscapularis tears identified during arthroscopy were retrospectively analyzed. Baseline characteristics, preoperative and follow-up (6 months) magnetic resonance imaging findings, arthroscopic findings, and clinical outcomes (>1 year) were recorded.

Results: The prevalence of subscapularis MAFI (Goutallier grade 1 or 2) was 73.9% (113/153), of which the prevalence of Goutallier grade 2 was 23.5% (36/153). From multivariable logistic regression analysis, female sex (odds ratio [OR], 5.6; 95% CI, 1.7-18.6; P=0.005), older age (OR, 1.1; 95% CI, 1.0-1.1; P=0.052), advanced supraspinatus MAFI by Goutallier grade (OR, 3.2; 95% CI, 1.5-6.9; P=0.004), and synovitis (OR, 2.8; 95% CI, 1.1-7.9; P=0.030) were identified as independent predisposing factors for subscapularis MAFI. However, patients with preoperative subscapularis MAFI exhibited similar final range of motion, pain and function, and belly press strength compared to those without preoperative subscapularis MAFI.

Conclusions: Subscapularis MAFI is frequently observed conditions even in the absence of subscapularis tears, and this condition could be affected by supraspinatus MAFI, female sex, older age, and synovitis. However, because subscapularis MAFI does not affect the surgical outcome, surgeons need not be concerned about this condition when repairing posterosuperior rotator cuff tear. Level of evidence: IV.

Keywords: Arthroscopy; Magnetic resonance imaging; Muscular atrophy; Subscapularis; Rotator cuff.

Fig. 1.

(A) Patients with isolated small to medium-sized supraspinatus tendon tear (arrow). (B) The Y-view of sagittal oblique imaging shows Goutallier grade 3 muscle atrophy and fatty infiltration in the supraspinatus and Goutallier grade 2 in the subscapularis (arrow: cog-shaped appearance in the upper subscapularis muscle). (C) However, no tear of the subscapularis tendon was identified during intra-articular arthroscopy (arrow).

Fig. 2.

Flow diagram of patient inclusion.

Fig. 3.

Modified Patte’s classification for rotator cuff retraction. (A) The distance from the greater tuberosity to the upper margin of the glenoid is divided into six segments, with scores ranging from 0 to 6. This modification offers a more detailed assessment of supraspinatus tendon retraction relative to the original Patte’s classification, independent of patient size. (B) A retraction of 1/6 of the supraspinatus tendon just medial to the greater tuberosity footprint (asterisk) is assigned a score of 1. (C) A retraction of half the supraspinatus tendon, reaching the upper tip of the humeral head (asterisk), is assigned a score of 3.

Fig. 4.

Goutallier classification grading. The corresponding areas for each grade are indicated by arrows: (A) Grade 1, a fatty streak observed between the subscapularis tendons. (B) Grade 2, less fat than muscle in the upper half of the muscle, presenting a cog-shaped appearance in the upper subscapularis muscle. (C) Grade 3, more fat than muscle in the upper half of the muscle, with normal or fatty streaks in the lower half. (D) Grade 4, more fat than muscle throughout the muscle.