Clinical application of musculoskeletal for supraspinatus tendon tears with fat infiltration

Introduction

Supraspinatus tendon tears are commonly associated with fat infiltration, a pathological process that increases tendon brittleness and thereby predisposes patients to re-tear as well as muscle belly atrophy (1,2). Furthermore, fat infiltration exceeding 50% is widely regarded as a relative contraindication to surgical intervention (3,4). Early detection of fat infiltration in the supraspinatus muscle holds significant clinical importance for predicting re-tears of the supraspinatus tendon (3,4).

Magnetic resonance imaging (MRI) is widely used to evaluate fat infiltration of the supraspinatus muscle in clinical practice, demonstrating relatively high diagnostic reliability. Fat infiltration appears hyperintense on T1-weighted imaging (T1WI) (5,6). The Goutallier classification system—among the most commonly employed semi-quantitative grading methods—assesses fat infiltration severity based on high-signal intensity observed in oblique sagittal T1WI sequences. A grade ≥3 indicates severe fat infiltration (7). However, practical limitations—such as scheduling requirements and its incompatibility in patients with metal implants—have somewhat restricted its broader clinical application (8). In contrast, musculoskeletal ultrasound (MSK US) has gained traction in the clinical diagnosis of limb joints and peripheral nerves, owing to its advantages of convenience, absence of radiation exposure, and high resolution.

Nevertheless, there is a relative scarcity of studies focusing on fat infiltration in the supraspinatus muscle using MSK US. This study aimed to investigate fat infiltration in patients with supraspinatus tendon tears using MSK US, with a focus on exploring its imaging characteristics and clinical significance. We present this article in accordance with the STROBE reporting checklist (available at https://qims.amegroups.com/article/view/10.21037/qims-2025-2024/rc).

Methods

Study subjects

In this retrospective study, a total of 155 patients with arthroscopically confirmed supraspinatus tendon tears were enrolled at Huzhou Central Hospital. Comprehensive medical histories and findings from physical examinations were systematically collected for all participants. All patients underwent both MSK US and MRI evaluations for the supraspinatus muscle. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. This study was approved by the Medical Ethics Committee of Huzhou Central Hospital (No. 202110024-02). Written informed consent was obtained from all the patients.

Inclusion criteria were as follows (4,9): (I) a documented history of shoulder joint pain accompanied by restricted mobility; (II) clinical history and physical examination indicative of a supraspinatus tendon injury; (III) definitive diagnosis of supraspinatus tendon tear established by shoulder arthroscopy.

Exclusion criteria were as follows: (I) neuromyography findings indicating abnormal sensory or motor amplitudes in the suprascapular nerve; (II) individuals exhibiting an allergy to gadolinium contrast agents when undergoing ultrasound-guided magnetic resonance angiography examination; (III) patients who underwent shoulder joint puncture and presented with abnormal coagulation function; those who had not ceased antiplatelet medication for at least three days prior to assessment; or those with active infection involving the shoulder joint or other body regions; (IV) individuals showing severe dysfunctions related to cardiac, hepatic, renal systems or those unable to tolerate the examination procedures; (V) a previous surgical history involving the shoulder joint; (VI) presence of other rheumatic autoimmune diseases such as osteoarthritis or rheumatoid arthritis.

Clinical examination

The enrolled patients were evaluated using Visual Analog Scale (VAS) scores for pain assessment, Active Range of Motion (AROM) scores for measuring shoulder flexion, extension, abduction, external rotation, and internal rotation, and Constant-Murley scores for comprehensive assessment of overall shoulder function (10).

Instrumentation and parameters

MSK US examination

MSK US examinations were performed using the Mindray R7T and Canon Aplio 900 ultrasound systems, featuring a probe frequency of 12 MHz. Examinations were conducted under specific conditions, with the color Doppler settings configured as follows: low-pass filtering, pulse repetition frequency ranging from 400 to 1,800 Hz, and maximum gain adjusted to ensure absence of Doppler signal posterior to the cortical bone.

The MSK US examination was collaboratively performed by an associate chief physician and a senior attending physician. Both of them received standardized training in the classification system and strictly adhered to the shoulder joint scanning protocols specified in the “Chinese Musculoskeletal Ultrasound Examination Guidelines”. In cases where diagnostic opinions diverged, resolution was sought through mutual consultation; any discrepancies remaining after discussion were excluded from consideration. Two-dimensional gray-scale ultrasound imaging was employed to scan the supraspinatus muscle located within the supraspinatus fossa on the affected side of each patient. For evaluating supraspinatus muscle fat infiltration, target areas were selected based on marked echogenic enhancement observed in both longitudinal and transverse planes; these regions were systematically evaluated utilizing combined transverse and longitudinal scanning (9).

The SWE assessment was performed with the region of interest (ROI) positioned along the long axis of supraspinatus muscle (square ROI: 1 cm × 1 cm; depth: centered at the mid-portion of the supraspinatus muscle) (11). The patient was seated in a standardized position: shoulder at 0° abduction and 0° flexion, with neutral rotation; elbow flexed 90° and forearm resting gently on the ipsilateral thigh. The shoulder was maintained in a completely relaxed state without active contraction or passive tension before shear wave elastography (SWE) was performed. This method showed significant echo enhancement due to fat infiltration within the supraspinatus muscle; SWE values were recorded accordingly. Measurements were taken three times for each site to obtain an average value. In instances where there was no evidence of fat infiltration by MSK US in patients, SWE measurements focused on targeting the center along the long axis of the supraspinatus muscle (9).

Semi-quantitative grading for assessing fat infiltration in the supraspinatus muscle by MSK US was outlined as follows (4).

• Grade 1: normal appearance characterized by clear pennate structural texture within the supraspinatus muscle; moderate hypoechoic echogenicity observed; smooth cortex noted within suparspinous fossa with sharp edges; prominent echo enhancement accompanied by distinct acoustic shadowing (Figure 1A).
• Grade 2: the supraspinatus muscle exhibited localized blurring of its pennate structural texture. Echogenicity was enhanced in specific areas, approaching but not surpassing the echo intensity of the cortical bone within the supraspinatus fossa. The boundary between the supraspinatus muscle and the cortical bone remained distinctly defined. Additionally, mind blurring of the cortical bone shadow was observed (Figure 1B).
• Grade 3: the pennate structural texture of the supraspinatus muscle were notably blurred, accompanied by patchy echo enhancement within the muscle itself. The delineation between the supraspinatus muscle and the adjacent cortical bone became indistinct. Furthermore, the cortical bone exhibited diminished hyperechoic signal and acoustic shadowing; both sound and shadow appeared blurred, resulting in an unclear boundary with respect to the supraspinatus muscle (Figure 1C).
• Grade 4: marked blurring of the pennate texture within the supraspinatus muscle was present, with significant enhancement observed in echo intensity. The interface between the supraspinatus muscle and the underlying cortical bone lacked clarity; critically, strong echoes and acoustic shadows from this cortical bone were absent (Figure 1D).

Figure 1 Semi-quantitative grading for assessing fat infiltration in the supraspinatus muscle by MSK US. (A) Grade 1. (B) Grade 2. (C) Grade 3. (D) Grade 4. Long arrows indicated the echogenicity and texture of the supraspinatus, while dovetail arrows highlighted the cortical bone echo of the supraspinatus fossa. MSK US, musculoskeletal ultrasound.

MRI examination

A GE 3.0 T MRI scanner (GE Healthcare, USA) equipped with a dedicated shoulder coil was used for MRI examination. Standard imaging planes included transverse, oblique sagittal and oblique coronal orientations. The imaging protocol comprised the following sequences: spin echo (SE) T1WI coronal and oblique sagittal planes [repetition time (TR) 500 ms, echo time (TE) 22 ms, matrix 256×256, slice thickness 3 mm, interval 0.3 mm], fast SE (FSE), T2-weighted imaging (T2WI) coronal (TR 3,000 ms, TE 85 ms, matrix 256×256, slice thickness 3 mm, interval 0.3 mm) and protondensity weighted imaging. The semi-quantitative grading of supraspinatus muscle fatty infiltration by MRI was performed independently by two MRI physicians with reference to Goutallier grading method (7).

Semi-quantitative grading of supraspinatus muscle fat infiltration by MRI was as follows.

• Grade 0: normal muscle appearance with no evident fat infiltration (Figure 2A).
• Grade 1: minimal fat infiltration was present, characterized by a few streaks or bands of high signal intensity within the supraspinatus muscle (Figure 2B).
• Grade 2: the presence of patchy high-signal areas within the supraspinatus muscle, occupying <50% of the total muscle volume (Figure 2C).
• Grade 3: patchy high-signal areas within the supraspinatus muscle equal to or exceeding 50% of the muscle volume (Figure 2D).
• Grade 4: a substantial patch of high-signal area within the supraspinatus muscle, with fat occupying >50% of the total muscle volume (Figure 2E).

Figure 2 MRI images illustrating grades of fat infiltration in the supraspinatus muscle from Grade 0 to 4. (A) Grade 0. (B) Grade 1. (C) Grade 2. (D) Grade 3. (E) Grade 4. MRI, magnetic resonance imaging.

Arthroscopic examination

Shoulder arthroscopy was performed utilizing the Xerox arthroscopy system, in collaboration with an associate chief physician from the Department of Joint Surgery and an attending physician. The severity of supraspinatus tendon tears was classified according to Ellman’s tear classification: Grade I (mild): tear depth <3 mm; Grade II (moderate): 3 mm ≤ tear depth ≤6 mm; Grade III (severe): tear depth >6 mm (12).

Statistical analysis

Statistical analyses were conducted using SPSS version 21.0. Qualitative data were presented as rates, while quantitative data that conformed to a normal distribution were expressed as mean ± standard deviation (±s). For non-normally distributed continuous variables, data were reported as median (M) and interquartile range (Q). Group differences were assessed using t-tests, Chi-squared tests, or Fisher’s exact probability method. Receiver operating characteristic (ROC) curve was utilized to evaluate the sensitivity and specificity; the area under the ROC curve (AUC) and optimal cut-off value were calculated accordingly. The consistency of diagnoses between the two examination methods was evaluated through Cohen’s kappa (κ) statistic: κ>0.75 indicated good consistency; 0.4≤κ≤0.75, moderate consistency; κ<0.4, poor consistency. Spearman’s rank correlation analysis was performed to assess associations between ordinal or non-normally distributed continuous variables. A P<0.05 was considered statistically significant.

Results

General clinical data

Among the 155 patients initially screened, one case was excluded due to incomplete data. Consequently, a total of 154 patients with supraspinatus tendon tears were enrolled in this study, comprising 42 males (27.27%) and 112 females (72.73%). The average age of participants was 51.26±10.45 years, with a mean disease duration of 6.12±2.36 months. Preoperative assessments revealed an average VAS score for pain of 7.32±3.81, a mean AROM score of 17.61±6.94 for shoulder joint mobility, and a Constant-Murley score of 44.63±5.61, reflecting overall shoulder function.

Arthroscopic examination classified the tears as follows: full-thickness tears were identified in 50 patients (32.47%), and partial tears were observed in the remaining 104 patients (67.53%). Among the partial tears, 34 (22.08%) were lateral articular-sides, 32 (20.78%) were lateral bursal-sided, and 38 (24.68%) were interstitial. In terms of tear severity classification, 22 cases (14.29%) were Grade I, 38 (24.68%) were Grade II, and 94 (61.04%) were Grade III.

Comparison of shear wave velocities of fat infiltration in the supraspinatus muscle among patients with supraspinatus tendon tears

Among 154 patients with supraspinatus tendon tears, SWE on the affected side was significantly lower (2.52±0.56 cm/s) than that recorded on the healthy side (3.03±0.64 cm/s); this difference was statistically significant (t=7.42, P<0.001).

Comparison of MSK US and MRI for fat infiltration in the supraspinatus muscle

Among 154 patients with supraspinatus muscle fat infiltration identified by MSK US, the distribution of cases by grade was as follows: Grade 1 (n=51), Grade 2 (n=59), Grade 3 (n=29) and Grade 4 (n=15) (Table 1). By contrast, MRI-based grading yielded the following distribution: Grade 0 (n=56), Grade 1 (n=49), Grade 2 (n=34), and Grade 3/4 (n=15). Using MRI as the gold standard, MSK US demonstrated 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 AUC of 0.89 [95% confidence interval (CI): 0.77–0.98] (Figure 3). The consistency of the diagnosis between MSK US and MRI for fat infiltration was moderate, with Cohen’s kappa coefficient of 0.75 (95% CI: 0.67–0.84, P<0.0001).

Figure 3 The AUC value of MSK US for diagnosing fat infiltration in the supraspinatus muscle. AUC, area under the receiver operating characteristic curve; MSK US, musculoskeletal ultrasound.

Correlation between degree of supraspinatus tendon tear and degree of fat infiltration in the supraspinatus muscle by MSK US

The relationship between the degree of supraspinatus tendon tear, as assessed by Shoulder arthroscopy, and the degree of supraspinatus muscle fat infiltration by MSK US is presented in Table 2. Spearman’s rank correlation analysis revealed a significant correlation between the degree of fat infiltration in the supraspinatus muscle through MSK US and the extent of arthroscopically confirmed supraspinatus tendon tear among the 154 patients (r_s=0.47, P<0.001). These findings indicated that more severe tears in the supraspinatus tendon were associated with higher degrees of fat infiltration within its corresponding muscle.

Discussion

Following a supraspinatus tendon tear, both the supraspinatus muscle and its tendon are prone to fat infiltration—a pathological process that further exacerbates tendon brittleness, impairs supraspinatus muscle function, and elevates the risk of tendon re-tear. This creates a vicious cycle (7,13,14). Consequently, early detection of fat infiltration in the supraspinatus muscle and timely intervention are critically important for preserving shoulder joint function and preventing re-tears.

With the increasing clinical application of MSK US, this imaging method is capable not only in detecting supraspinatus tendon tears but also in evaluating the degree of fat infiltration by observing changes in echo intensity within the supraspinatus muscle belly (1,3,13). Tseng et al. reported that MSK US in diagnosing supraspinatus muscle fat infiltration showed high concordance with the Goutallier classification method employed by MRI (15). Khoury et al. found that MSK US diagnosis of fat infiltration in the supraspinatus muscle exhibited a strong correlation with MRI diagnoses (R=0.9) (1). Our study indicated that MSK US achieved an overall accuracy of 90.3%, an AUC of 0.89 and a Cohen’s kappa coefficient of 0.75, suggesting moderate diagnostic consistency between MSK US and MRI regarding grading fat infiltration in the supraspinatus muscle. When performing MSK US to detect fat infiltration in the supraspinatus muscle, careful attention should be paid to the integrity and definition of the central pennate architecture; the presence of diffuse or focal hyperechoic areas—representing fatty infiltration or deposition—should be systematically assessed. In atypical cases, enhancing echo contrast, with either superficial trapezius muscles or healthy portions of the supraspinatus, can significantly improve diagnostic reliability concerning fat infiltration assessment by MSK US (13,16).

Among 154 patients with supraspinatus tendon tears, the results of SWE revealed that tendon rupture altered the elastic mechanical properties of the muscle, resulting in reduced muscle stiffness. SWE quantifies tissue stiffness by measuring the propagation speed of shear waves. In this study, the SWE results on the affected side were significantly lower than that on the healthy side—consistent with the expected biomechanical consequences of tendon injury on muscle function. However, our findings partially diverge from those reported by Peeters et al. (17). Their study found only a weak correlation between SWE measurements and conventional MRI-based grading of rotator cuff fat infiltration and muscle atrophy, concluding that SWE lacked sufficient reliability for assessing rotator cuff tissue texture. This discrepancy may stem from differences in study design and analytical focus: our study employed a within-subject (ipsilateral-contralateral) control design to minimize inter-individual variability and specifically examined the direct effect of tendon tear on supraspinatus muscle elasticity; in contrast, Peeters et al. primarily evaluated the complementary diagnostic utility of SWE relative to established imaging-based grading systems. It is important to recognize that SWE reflects the integrated mechanical behavior of tissue, which is influenced by multiple coexisting pathological processes—including fat infiltration, fibrosis, and edema. Consequently, SWE cannot isolate or precisely quantify any single histopathological change. Nevertheless, its sensitivity to overall alterations in muscle elasticity remains robust and clinically meaningful.

Following a supraspinatus tendon tear occurs, adipose tissue accumulates both within and around the muscle bundle, as well as within the tendon itself; this contributes to increased brittleness of the muscle belly and tendon (18,19). Watanabe et al. observed that the intensity and proportion of hyperechoic areas in the abdominal region of the supraspinatus muscle escalated with the severity of supraspinatus tendon tears (20). Similarly, Barry et al. reported a close relationship between fat infiltration in the supraspinatus muscle and both the size and severity of supraspinatus tendon tears, and multivariate analysis indicated that the degree of supraspinatus tendon tear was an independent risk factor for fat infiltration in the supraspinatus muscle (7). Collectively, our results demonstrated a significant correlation between fat infiltration and the extent of supraspinatus tendon tears by MSK US; notably, fat infiltration increased concomitantly with greater degrees of tendonal injury.

The underlying mechanisms driving fat infiltration in the supraspinatus muscle remain incompletely understood. Emerging evidence indicated that this pathological process may be associated with chronic strain on muscles or tendons, pathological changes in the nerves controlling these muscles, and age-related factors (18,21). Beeler et al. observed no significant difference in either the degree or distribution pattern of fat infiltration in the supraspinatus muscle between patients with supraspinatus tendon tears and those with supraspinatus neuropathy (22). However, they noted that, in patients with tendon tears, progressive fat infiltration was accompanied by a gradual loss of demarcation at the infiltrative boundary within the supraspinatus muscle. Furthermore, advancing age has been consistently correlated with increased intramuscular fat deposition. Sunny et al. showed that among patients aged ≥60 years with supraspinatus tendon tears, up to 40% demonstrated fat infiltration graded at grade ≥2 (23). Barry et al. identified age (odds ratio =1.05) as an independent risk factors contributing to supraspinatus muscle fat infiltration in a multivariate regression analysis (7).

The origin of adipocytes during the fat infiltration following a supraspinatus tendon tear remains incompletely clarified. These adipocytes may derive from pluripotent stem cells within the supraspinatus tendon tissue or from pre-existing adipocytes in other tissues by chemotaxis. Under conditions of tension and traction, muscle fibers would activate the Wnt signaling pathway, which serves to inhibit the activation of adipocytes. Conversely, when tendons lose their adhesion, the Wnt signaling pathway will be affected. This influence facilitates the transformation of pluripotent stem cells within muscle fiber tissue into adipocytes, leading to fat infiltration in the affected tissue. Consequently, addressing how to effectively repair supraspinatus tendon tears and restore tendon tension is crucial for mitigating fat infiltration into both the supraspinatus tendon and surrounding abdominal muscles. This approach is essential for reducing re-tearing incidents and preventing recurrence. Emerging minimally invasive technologies, such as platelet-rich plasma regenerative medicine and radiofrequency thermocoagulation, hold promise for enhancing tendon healing.

There are several limitations in this study: (I) no reliability studies; (II) no assessment of infraspinatus or teres minor muscles; (III) the relationship with tear chronicity is not provided; (IV) in this study, supraspinatus tendon tear severity was classified based on tear depth. For tears classified at the same severity grade, differences may exist regarding the extent of the tear and degree of fat infiltration into the supraspinatus muscle. We plan to expand our sample size for more comprehensive research in future studies.

Conclusions

The diagnostic consistency between MSK US and MRI for assessing fat infiltration in the supraspinatus muscle was found to be moderate, indicating significant clinical applicability. Furthermore, fat infiltration in the supraspinatus muscle exhibited a strong correlation with the severity of supraspinatus tendon tears. Specifically, an increase in the degree of supraspinatus tendon tear was associated with a greater extent of fat infiltration within the supraspinatus muscle by MSK US imaging.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://qims.amegroups.com/article/view/10.21037/qims-2025-2024/rc

Data Sharing Statement: Available at https://qims.amegroups.com/article/view/10.21037/qims-2025-2024/dss

Funding: This study was funded by Medical and Health Science and Technology Project of Zhejiang Province (No. 2022RC263).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-2025-2024/coif). All authors report receiving funding from the Medical and Health Science and Technology Project of Zhejiang Province. The authors have no other conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. This study was approved by the Medical Ethics Committee of Huzhou Central Hospital (No. 202110024-02). Written informed consent was obtained from all the patients.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Khoury V, Cardinal E, Brassard P. Atrophy and fatty infiltration of the supraspinatus muscle: sonography versus MRI. AJR Am J Roentgenol 2008;190:1105-11. [Crossref] [PubMed]
2. Yamamoto N, Mineta M, Kawakami J, Sano H, Itoi E. Risk Factors for Tear Progression in Symptomatic Rotator Cuff Tears: A Prospective Study of 174 Shoulders. Am J Sports Med 2017;45:2524-31. [Crossref] [PubMed]
3. Stengaard K, Hejbøl EK, Jensen PT, Degn M, Ta TML, Stensballe A, Andersen DC, Schrøder HD, Lambertsen KL, Frich LH. Early-stage inflammation changes in supraspinatus muscle after rotator cuff tear. J Shoulder Elbow Surg 2022;31:1344-56. [Crossref] [PubMed]
4. Chen PC, Wu KT, Chen YC, Huang YC, Chang CD, Lin WC, Chou WY. Predicting the surgical reparability of large-to-massive rotator cuff tears by B-mode ultrasonography: a cross-sectional study. Ultrasonography 2022;41:177-88. [Crossref] [PubMed]
5. Davis DL, Gilotra MN, Calderon R, Roberts A, Hasan SA. Reliability of supraspinatus intramuscular fatty infiltration estimates on T1-weighted MRI in potential candidates for rotator cuff repair surgery: full-thickness tear versus high-grade partial-thickness tear. Skeletal Radiol 2021;50:2233-43. [Crossref] [PubMed]
6. Ro K, Kim JY, Park H, Cho BH, Kim IY, Shim SB, Choi IY, Yoo JC. Deep-learning framework and computer assisted fatty infiltration analysis for the supraspinatus muscle in MRI. Sci Rep 2021;11:15065. [Crossref] [PubMed]
7. Barry JJ, Lansdown DA, Cheung S, Feeley BT, Ma CB. The relationship between tear severity, fatty infiltration, and muscle atrophy in the supraspinatus. J Shoulder Elbow Surg 2013;22:18-25. [Crossref] [PubMed]
8. Kim JH, Park JW, Heo SY, Noh YM. Magnetic resonance imaging analysis of rotator cuff tear after shoulder dislocation in a patient older than 40 years. Clin Shoulder Elb 2020;23:144-51. [Crossref] [PubMed]
9. Lawrence RL, Ruder MC, Moutzouros V, Makhni EC, Muh SJ, Siegal D, Soliman SB, van Holsbeeck M, Bey MJ. Ultrasound shear wave elastography and its association with rotator cuff tear characteristics. JSES Int 2021;5:500-6. [Crossref] [PubMed]
10. Jo YH, Lee KH, Jeong SY, Kim SJ, Lee BG. Shoulder outcome scoring systems have substantial ceiling effects 2 years after arthroscopic rotator cuff repair. Knee Surg Sports Traumatol Arthrosc 2021;29:2070-6. [Crossref] [PubMed]
11. Wong KY, Lau MW, Lee MH, Chan CH, Mak SH, Ng CF, Ying MTC. Study on the effects of arm abduction angle and cushion support during sonographic examination on the stiffness of supraspinatus muscle of sonographers using shear wave elastography. J Occup Health 2021;63:e12306. [Crossref] [PubMed]
12. Ellman H. Diagnosis and treatment of incomplete rotator cuff tears. Clin Orthop Relat Res 1990;64-74.
13. Park BK, Hong SH, Jeong WK. Effectiveness of Ultrasound in Evaluation of Fatty Infiltration in Rotator Cuff Muscles. Clin Orthop Surg 2020;12:76-85. [Crossref] [PubMed]
14. Donohue NK, Nickel BT, Grindel SI. High-Grade Articular, Bursal, and Intratendinous Partial-Thickness Rotator Cuff Tears: A Retrospective Study Comparing Functional Outcomes After Completion and Repair. Am J Orthop (Belle Mead NJ) 2016;45:E254-60.
15. Tseng YH, Chou WY, Wu KT, Chang CD, Chen YC, Huang YC, Lin WC, Chen PC. Use sonoelastography to predict the reparability of large-to-massive rotator cuff tears. Medicine (Baltimore) 2020;99:e21139. [Crossref] [PubMed]
16. Seo JB, Yoo JS, Ryu JW. The accuracy of sonoelastography in fatty degeneration of the supraspinatus: a comparison of magnetic resonance imaging and conventional ultrasonography. J Ultrasound 2014;17:279-85. [Crossref] [PubMed]
17. Peeters NHC, van der Kraats AM, van der Krieken TE, van Iersel D, Janssen ERC, Heerspink FOL. The validity of ultrasound and shear wave elastography to assess the quality of the rotator cuff. Eur Radiol 2024;34:1971-8. [Crossref] [PubMed]
18. Sahai A, Jones DL, Hughes M, Pu A, Williams K, Iyer SR, Rathinam C, Davis DL, Lovering RM, Gilotra MN. Fibroadipogenic progenitor cell response peaks prior to progressive fatty infiltration after rotator cuff tendon tear. J Orthop Res 2022;40:2743-53. [Crossref] [PubMed]
19. Mendez GM, Manske RC, Smith BS, Prohaska DJ. Supraspinatus Fatty Infiltration Correlation with Handgrip Strength, Shoulder Strength, and Validated Patient-Reported Outcome Measures in Patients with Rotator Cuff Tears. Kans J Med 2022;15:155-9. [Crossref] [PubMed]
20. Watanabe T, Terabayashi N, Fukuoka D, Murakami H, Ito H, Matsuoka T, Seishima M. A pilot study to assess Fatty infiltration of the supraspinatus in patients with rotator cuff tears: comparison with magnetic resonance imaging. Ultrasound Med Biol 2015;41:1779-83. [Crossref] [PubMed]
21. Cartucho A. Tendon transfers for massive rotator cuff tears. EFORT Open Rev 2022;7:404-13. [Crossref] [PubMed]
22. Beeler S, Ek ET, Gerber C. A comparative analysis of fatty infiltration and muscle atrophy in patients with chronic rotator cuff tears and suprascapular neuropathy. J Shoulder Elbow Surg 2013;22:1537-46. [Crossref] [PubMed]
23. Cheung S, Dillon E, Tham SC, Feeley BT, Link TM, Steinbach L, Ma CB. The presence of fatty infiltration in the infraspinatus: its relation with the condition of the supraspinatus tendon. Arthroscopy 2011;27:463-70. [Crossref] [PubMed]