MRI quantification of fatty infiltration and muscle atrophy in a mouse model of rotator cuff tears

Background: Rotator cuff muscle atrophy and fatty infiltration are predictors of negative outcomes after rotator cuff repair. However, the impact of muscle degeneration on nonsurgical treatment is unknown. Hypothesis: Rotator cuff muscle atrophy and fatty infiltration will reduce the outcomes of operative repair while having a minimal effect on nonsurgical treatment. Additionally, in the setting of atrophy and fatty infiltration, surgical and nonsurgical treatment will produce equivalent outcomes. Study Design: Cohort study; Level of evidence, 2. Methods: Patients undergoing operative and nonoperative treatment of full-thickness rotator cuff tears were prospectively enrolled into a nonrandomized cohort study. Muscle quality was assessed on magnetic resonance imaging by use of the supraspinatus tangent sign, Warner atrophy, and Goutallier fatty infiltration classifications. Grading was performed by 2 independent observers who were blinded to patient treatment and outcomes. Normalized Western Ontario Rotator Cuff (WORC) index was the primary patient-reported outcome. Multivariate linear regression analysis was used to determine the impact of muscle quality on treatment outcomes. Results: The cohort consisted of 157 patients, 89 (57%) surgical and 68 (43%) nonsurgical, with a mean follow-up of 2.4 years (range, 1-5 years). Tangent sign had the best inter- and intrarater reliability, with kappa statistics of 0.81 and 0.86, respectively. Reliability for Warner atrophy was 0.69 to 0.76 and for Goutallier classification was 0.54 to 0.64. Overall, improvement in WORC scores was higher in the surgical group than the nonsurgical group (39.3 vs 21.2; P < .001). A positive tangent sign was the only independent predictor ( P < .01) of worse outcomes in the surgical group, accounting for an estimated 22-point lower improvement in WORC scores. Conclusion: A positive tangent sign was predictive of worse operative outcomes, resulting in equivalent improvements between surgical and nonsurgical treatment. The tangent sign is a reliable, prognostic indicator that clinicians can use when counseling patients on the optimal treatment of rotator cuff tears.

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A Mouse Model of Delayed Rotator Cuff Repair Results in Persistent Muscle Atrophy and Fatty Infiltration

The American Journal of Sports Medicine ◽

10.1177/0363546518793403 ◽

2018 ◽

Vol 46 (12) ◽

pp. 2981-2989 ◽

Cited By ~ 15

Author(s):

Zili Wang ◽

Xuhui Liu ◽

Michael R. Davies ◽

Devante Horne ◽

Hubert Kim ◽

...

Keyword(s):

Rotator Cuff ◽

Mouse Model ◽

Mechanical Testing ◽

Muscle Atrophy ◽

Molecular Mechanisms ◽

Ex Vivo ◽

Fatty Infiltration ◽

Shoulder Function ◽

Muscle Weight ◽

Orthopaedic Patients

Background: Rotator cuff (RC) tears are common tendon injuries seen in orthopaedic patients. Successful repair of large and massive RC tears remains a challenge due to our limited understanding of the pathophysiological features of this injury. Clinically relevant small animal models that can be used to study the pathophysiological response to repair are limited by the lack of chronic repair models. Purpose: To develop a highly clinically relevant mouse model of delayed RC repair. Study Design: Controlled laboratory study. Methods: Three-month-old C57BL/6J mice underwent unilateral supraspinatus (SS) and infraspinatus (IS) tendon tear with immediate, 2-week delayed, or 6-week delayed tendon repair. Animals with no repair or sham surgery served as controls. Gait analysis was conducted to measure shoulder function at 2 weeks and 6 weeks after surgery. Animals were sacrificed 6 weeks after the last surgery. Shoulder joint, SS, and IS muscles were harvested and analyzed histologically. Ex vivo mechanical testing of intact and repaired SS and IS tendons was conducted. Reverse-transcriptase polymerase chain reaction was performed on SS and IS muscles to quantify atrophy, fibrosis, and fatty infiltration–related gene expression. Results: Histological and tendon mechanical testing showed that torn tendons could be successfully repaired as late as 6 weeks after transection. However, significant atrophy and fatty infiltration of muscle, with impaired shoulder function, were persistent in the 6-week delayed repair group. Shoulder function correlated with the severity of RC muscle weight loss and fatty infiltration. Conclusion: We successfully developed a clinically relevant mouse model of delayed RC repair. Six-week delayed RC repair resulted in persistent muscle atrophy and fatty infiltration with inferior shoulder function compared with acute repair. Clinical Relevance: Our novel mouse model could serve as a powerful tool to understand the pathophysiological and cellular/molecular mechanisms of RC muscle and tendon degeneration, eventually improving our strategies for treating and repairing RC tears.

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How common is fatty infiltration of the teres minor in patients with shoulder pain? A review of 7,367 consecutive MRI scans

Journal of Experimental Orthopaedics ◽

10.1186/s40634-021-00325-2 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

William R. Aibinder ◽

Derrick A. Doolittle ◽

Doris E. Wenger ◽

Joaquin Sanchez-Sotelo

Keyword(s):

Rotator Cuff ◽

Shoulder Pain ◽

Muscle Atrophy ◽

External Rotation ◽

Reverse Shoulder Arthroplasty ◽

Fatty Infiltration ◽

Deltoid Muscle ◽

Rotator Cuff Tears ◽

Shoulder Mri ◽

Teres Minor

Abstract Purpose The teres minor is particularly important for activities that require external rotation in abduction in the settings of both rotator cuff tears and reverse shoulder arthroplasty. This study sought to assess the incidence of teres minor fatty infiltration in a large cohort of consecutive patients evaluated with shoulder MRI for shoulder pain and to identify all associated pathologies in an effort to determine the various potential etiologies of teres minor involvement. Methods A retrospective review of 7,376 non-contrast shoulder MRI studies performed between 2010 and 2015 were specifically evaluated for teres minor fatty infiltration. Studies were reviewed by two fellowship trained musculoskeletal radiologists. Muscle atrophy was graded on a 3-point scale according to Fuchs and Gerber. The remaining rotator cuff tendons and muscles, biceps tendon, labrum, and joint surfaces were assessed on MRI as well. Results In this series, 209 (2.8%) shoulders were noted to have fatty infiltration of the teres minor. The rate of isolated fatty infiltration of the teres minor was 0.4%. Concomitant deltoid muscle atrophy was common, and occurred in 68% of the shoulders with fatty infiltration of the teres minor. Tearing of the teres minor tendon was extremely rare. Conclusion Fatty infiltration of the teres minor can occur in isolation, be associated with deltoid muscle atrophy only, or occur in the setting of rotator cuff full tears. Thus, fatty infiltration of the teres minor may be related to a neurologic process or disuse. Further long term longitudinal studies are necessary to be elucidate the etiologies. Level of Evidence Level IV.

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Fatty infiltration in the intact supraspinatus tendon; a normal physiological response with increasing age and female gender

Shoulder & Elbow ◽

10.1177/17585732211024504 ◽

2021 ◽

pp. 175857322110245

Author(s):

Ailsa Wilson ◽

Simon BM MacLean

Keyword(s):

Rotator Cuff ◽

Muscle Atrophy ◽

Surgical Repair ◽

Fatty Infiltration ◽

Female Gender ◽

Supraspinatus Tendon ◽

Rotator Cuff Tears ◽

Supraspinatus Muscle ◽

Cuff Tear ◽

3.0 T

Background Fatty infiltration and muscle atrophy of supraspinatus are used as markers of chronicity in rotator cuff tears and are known to both be independently related to poorer outcomes following surgical repair.1 We hypothesized that supraspinatus muscle atrophy and fatty infiltration increases with age irrespective of whether the rotator cuff is intact and therefore cannot be used as accurate markers for chronicity. Method Retrospective review of 280 patients who underwent 3.0 T shoulder MRI’s with either a normal scan or rotator cuff tear. Two independent observers reviewed the images. Data collected included intact rotator cuff tendons looking specifically at supraspinatus muscle height/length: suprascapular fossa ratio, tangent sign and Goutallier grade for fatty infiltration. Results There were 90 scans with intact rotator cuff tendons. Mean age was 51 years (range 17–86); 52 males, 38 females. On multiple regression analysis, there was a positive correlation of age with fatty infiltration and muscle atrophy on all parameters in the normal intact cuff. Females were significantly more likely than males to have a higher grade of fatty infiltration. Conclusion Age and female gender are risk factors for rotator cuff atrophy and fatty infiltration in patients with normal rotator cuffs. Therefore, these parameters should be used with caution by surgeons when deciding on tear chronicity and the potential to repair the torn rotator cuff.

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Primary versus revision arthroscopic bridging reconstruction using dermal allograft: a clinical and radiographic analysis (243)

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967121s00351 ◽

2021 ◽

Vol 9 (10_suppl5) ◽

pp. 2325967121S0035

Author(s):

Ivan Wong ◽

Sara Sparavalo ◽

Jie Ma ◽

Nedal Alkhatib

Keyword(s):

Rotator Cuff ◽

Muscle Atrophy ◽

Fatty Infiltration ◽

Rotator Cuff Tears ◽

Primary Group ◽

Dash Score ◽

Massive Rotator Cuff Tears ◽

Western Ontario Rotator Cuff ◽

Goutallier Classification

Objectives: Large or massive rotator cuff tears make up between 10-40% of all rotator cuff tears, yet there is no agreement on the best treatment. Previous studies have shown that acellular human dermal allograft (AHDA) can be used for bridging reconstruction with positive patient outcomes. The use of this surgical technique has not been extensively studied in the primary or revision surgical setting. The main objective of this study was to compare the clinical and radiographic outcomes of patients who received primary or revision arthroscopic bridging reconstruction. Methods: This study is a retrospective review of a sequential series of patients who underwent arthroscopic bridging reconstruction (ABR) using AHDA by the primary author (IW). A total of 130 patients underwent ABR between 2010 and 2018. The inclusion criteria were patients with completed Western Ontario Rotator Cuff (WORC) questionnaire, Disabilities of the Arm, Shoulder, and Hand (DASH) score, or both pre-operatively and at multiple post-operative timepoints. Patients with missing WORC scores were excluded from the study. Eighty-three patients were included following chart review. Patients with available post-operative MRIs were also used for radiological assessment by an independent MSK-trained radiologist. Post-operative MRIs were reviewed to assess for graft integrity and changes to rotator cuff muscle atrophy (using the Warner classification) and fatty degeneration (using the Goutallier classification). Results: There were 46 patients who received primary ABR and 37 who received revision ABR. Forty-eight patients had a post-operative MRI available for review (Primary: 25; Revision: 23). The demographics are summarized in Table 1. Both groups showed a significant improvement in WORC score post-operatively (p<0.001). Primary ABR resulted in higher post-operative WORC scores as compared to revision ABR (p=0.015; Figure 1). The incidence of complete re-tears in the primary group was 8% and 17.4% in the revision group. More than 35% of patients in the primary group showed improvement in fatty infiltration of the infraspinatus and supraspinatus muscles. There was a higher progression in muscle atrophy in the revision group as compared to the primary group (74% and 30%, respectively). Conclusions: Arthroscopic primary arthroscopic bridging reconstruction for large/massive rotator cuff tears using acellular human dermal allograft had better improvement in their WORC scores compared to revision group at the final follow-up. Although the revision group had improved at the two-year follow-up, these changes in WORC score were not sustained at the final follow-up while the improvements were maintained for the primary group. The primary group had a smaller re-tear rate, better fatty infiltration and muscle atrophy as compared to the revision group. This suggests that primary bridging reconstruction provides better outcomes than a revision surgery.

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