Development of a Computational Model to Study Effects of Rotator Cuff Tear Size and Location on Muscle Moment Arms

Rotator cuff tendon tear causes alterations to cuff muscle architecture and tendons including muscle fascicle contracture and increased tendon length, fatty infiltration of the muscle fibers, muscle fiber pennation angle changes, asymmetric muscle atrophy, and altered muscle fiber type composition, e.g. [1]. These changes ultimately result in a reduction in muscle force, and frequently lead to a reduction of shoulder strength and a loss of functionality. Recently, division of the cuff tendons in a manner related to cuff tear has been shown to alter tendon excursions and cause muscle moment arms reductions in a cadaver experiment [2] and a computational study [3]. Evaluations of the effects of cuff tear size and location on cuff muscle moment arms have not been conducted. Consequently, the mechanisms by which the muscle force and moment arm changes affect joint strength are not well understood. An improved understanding of these relationships would increase potential for rehabilitation of joint strength following cuff repair. Models for evaluating rotator cuff tear are non-existent since subject-specific models have focused on healthy normal shoulders. Consequently, models have not been used to quantify the effects of clinically observed changes in muscle and tendon architecture on muscle moment arm and force generating capacity.

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Diagnostic value of the axial view of magnetic resonance imaging to identify two-dimensional shapes of full-thickness rotator cuff tears

Acta Radiologica ◽

10.1177/0284185120905098 ◽

2020 ◽

Vol 61 (11) ◽

pp. 1545-1552

Author(s):

Sung-Weon Jung ◽

Jin-Woo Jin ◽

Dong-Hee Kim ◽

Hyeon-Soo Kim ◽

Gwang-Eun Lee ◽

...

Keyword(s):

Magnetic Resonance Imaging ◽

Magnetic Resonance ◽

Rotator Cuff ◽

Rotator Cuff Tear ◽

Fatty Infiltration ◽

Rotator Cuff Tears ◽

Two Dimensional ◽

Resonance Imaging ◽

Cuff Tear ◽

Tear Size

Background Coronal and sagittal views of magnetic resonance imaging (MRI) were used to determine rotator cuff tear size and fatty infiltration, but these images were not enough to identify the tear shape. Purpose To correlate the preoperative axial MRI views and arthroscopic surgical findings to identify the two-dimensional shapes in rotator cuff tears. Material and Methods This study included 166 patients who underwent arthroscopic repair between 2015 and 2018. Preoperative coronal, sagittal, and axial MRI views were evaluated for tear size and geographic configuration in axial sections, and the length and the width were measured and were matched with arthroscopic surgical views by lateral portals. Results The agreement of axial MRI views with the arthroscopic view was 88.0% in crescent, 97.2% in longitudinal, 78.6% in massive, and 100% in rotator cuff tear arthropathy. The mean agreement rate of axial MRI views with arthroscopic view was 81.9%. Mean mediolateral and anteroposterior tear sizes on axial MRI were 16.68 mm and 19.33 mm, respectively. Mean mediolateral and anteroposterior tear sizes by arthroscopic view were 21.49 mm and 21.04 mm, respectively. Tear sizes by MRI axial images were 71.3% of arthroscopic view. SST/IST degenerative changes were noted in most patients with massive tears and rotator cuff arthropathy ( P = 0.001). Conclusion Rotator cuff tear shape on preoperative axial MRI view had close agreement (81.9%) with arthroscopic findings by lateral portal, and tear size by preoperative axial MRI views was 71.3% of that of arthroscopic view. Axial MRI views helped to predict the geometric tear shape of rotator cuff tears.

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Retinoic Acid Receptor Agonists Suppress Muscle Fatty Infiltration in Mice

The American Journal of Sports Medicine ◽

10.1177/0363546520984122 ◽

2021 ◽

Vol 49 (2) ◽

pp. 332-339

Author(s):

Hideyuki Shirasawa ◽

Noboru Matsumura ◽

Masaki Yoda ◽

Kazumasa Okubo ◽

Masayuki Shimoda ◽

...

Keyword(s):

Gene Expression ◽

Skeletal Muscle ◽

Rotator Cuff ◽

Rotator Cuff Tear ◽

Gene Expression Analysis ◽

Retinoic Acid Receptor ◽

Adipogenic Differentiation ◽

Fatty Infiltration ◽

Cuff Tear

Background: The infiltration of fat tissue into skeletal muscle, a condition referred to as muscle fatty infiltration or fatty degeneration, is regarded as an irreversible event that significantly compromises the motor function of skeletal muscle. Purpose: To investigate the effect of retinoic acid receptor (RAR) agonists in suppressing the adipogenic differentiation of fibroadipogenic progenitors (FAPs) in vitro and fatty infiltration after rotator cuff tear in mice. Study Design: Controlled laboratory study. Methods: FAPs isolated from mouse skeletal muscle were cultured in adipogenic differentiation medium in the presence or absence of an RAR agonist. At the end of cell culture, adipogenic differentiation was evaluated by gene expression analysis and oil red O staining. A mouse model of fatty infiltration—which includes the resection of the rotator cuff, removal of the humeral head, and denervation the supraspinatus muscle—was used to induce fatty infiltration in the supraspinatus muscle. The mice were orally or intramuscularly administered with an RAR agonist after the surgery. Muscle fatty infiltration was evaluated by histology and gene expression analysis. Results: RAR agonists effectively inhibited the adipogenic differentiation of FAPs in vitro. Oral and intramuscular administration of RAR agonists suppressed the development of muscle fatty infiltration in the mice after rotator cuff tear. In accordance, we found a significant decrease in the number of intramuscular fat cells and suppressed expression in adipogenic markers. RAR agonists also increased the expression of the transcripts for collagens; however, an accumulation of collagenous tissues was not histologically evident in the present model. Conclusion: Muscle fatty infiltration can be alleviated by RAR agonists through suppressing the adipogenic differentiation of FAPs. The results also suggest that RAR agonists are potential therapeutic agents for treating patients who are at risk of developing muscle fatty infiltration. The consequence of the increased expression of collagen transcripts by RAR agonists needs to be clarified. Clinical Relevance: RAR agonists can be used to prevent the development of muscle fatty infiltration after rotator cuff tear. Nevertheless, further studies are mandatory in a large animal model to examine the safety and efficacy of intramuscular injection of RAR agonists.

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Recovery of Muscle Strength After Intact Arthroscopic Rotator Cuff Repair According to Preoperative Rotator Cuff Tear Size

The American Journal of Sports Medicine ◽

10.1177/0363546515625043 ◽

2016 ◽

Vol 44 (4) ◽

pp. 972-980 ◽

Cited By ~ 9

Author(s):

Sang-Jin Shin ◽

Jaeyoon Chung ◽

Juyeob Lee ◽

Young-Won Ko

Keyword(s):

Rotator Cuff ◽

Muscle Strength ◽

Rotator Cuff Tear ◽

Rotator Cuff Repair ◽

Arthroscopic Rotator Cuff Repair ◽

Cuff Tear ◽

Arthroscopic Rotator Cuff ◽

Cuff Repair ◽

Tear Size

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The association between Interleukin-6 rs1800795/rs1800797 polymorphisms and risk of rotator cuff tear in a Chinese population

Bioscience Reports ◽

10.1042/bsr20200193 ◽

2020 ◽

Vol 40 (4) ◽

Cited By ~ 1

Author(s):

Jin Li ◽

Lifeng Jiang ◽

Xindie Zhou ◽

Lidong Wu ◽

Dong Li ◽

...

Keyword(s):

Rotator Cuff ◽

Rotator Cuff Tear ◽

Constant Score ◽

Enzyme Linked Immunosorbent Assay ◽

Mutant Genotype ◽

Cuff Tear ◽

Increased Risk ◽

Polymerase Chain ◽

Tear Size

Abstract Expression of proinflammatory cytokines, such as interleukin (IL)-6 (IL-6) and metalloproteases, are elevated in patients with rotator cuff tear (RCT). In order to investigate the role of IL-6 gene polymorphisms on RCT risk, we genotyped two SNPs on IL-6 gene (rs1800795 and rs1800797) in 138 RCT patients and 137 healthy controls using polymerase chain reaction (PCR) and Sanger sequencing. The IL-6 expression in shoulder joint synovial fluid was determined by using enzyme-linked immunosorbent assay (ELISA) method. The constant score and visual analog scale (VAS) were used to evaluate the clinical outcome of two s (surgicsal vs. conservative) for RCT patients. For rs1800795, individuals with the GG genotype or G allele had significantly higher risk of RCT. Elevated risk of tear size was associated with the GG genotype of the rs1800795 polymorphism. The IL-6 rs1800797 polymorphism was also associated with an increased risk of RCT, especially among female, drinkers, and individuals with B(MI) < 25 kg/m2. The elevated levels of IL-6 gene were observed among the mutant genotype of rs1800795/rs1800797 polymorphism. Surgical group is significantly better than conservative treatment from the perspective of constant score and VAS. Furthermore, CG genotype of rs1800795 polymorphism increased the constant score at 6 months in comparison with CC genotype. In conclusion, our study supports a role of IL-6 rs1800795/rs1800797 polymorphisms on increased RCT risk. The RCT patients with CG genotype of rs1800795 polymorphism have more obvious surgical treatment effects by influencing the IL-6 expression.

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Fatty acid-binding protein 4 regulates fatty infiltration after rotator cuff tear by hypoxia-inducible factor 1 in mice

Journal of Cachexia Sarcopenia and Muscle ◽

10.1002/jcsm.12203 ◽

2017 ◽

Vol 8 (5) ◽

pp. 839-850 ◽

Cited By ~ 10

Author(s):

Yong-Soo Lee ◽

Ja-Yeon Kim ◽

Kyung-Soo Oh ◽

Seok Won Chung

Keyword(s):

Fatty Acid ◽

Rotator Cuff ◽

Rotator Cuff Tear ◽

Fatty Acid Binding Protein ◽

Fatty Infiltration ◽

Hypoxia Inducible Factor ◽

Fatty Acid Binding ◽

Hypoxia Inducible Factor 1 ◽

Acid Binding Protein ◽

Cuff Tear

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Rotator Cuff Tear Size Regulates Fibroadipogenic Progenitor Number and Gene Expression Profile in the Supraspinatus Independent of Patient Age

The American Journal of Sports Medicine ◽

10.1177/03635465211054512 ◽

2021 ◽

pp. 036354652110545

Author(s):

Michael R. Davies ◽

Hannah Chi ◽

Gurbani Kaur ◽

Mengyao Liu ◽

C. Benjamin Ma ◽

...

Keyword(s):

Gene Expression ◽

Rotator Cuff ◽

Rotator Cuff Tear ◽

Expression Profiles ◽

Gene Expression Profiles ◽

Patient Age ◽

Cuff Tear ◽

Patient Âgé ◽

Beige Adipocytes ◽

Tear Size

Background: Fatty infiltration of rotator cuff muscle is a limiting factor in the success of repairs. Fibroadipogenic progenitors (FAPs) are a population of stem cells within the rotator cuff that can differentiate into white adipocytes, fibroblasts, and beige adipocytes. The effects of patient age and rotator cuff tendon tear size on the number, differentiation patterns, and gene expression profiles of FAPs have not yet been analyzed. Purpose: To determine if patient age and rotator cuff tear size independently regulate FAP number, differentiation patterns, and gene expression profiles. Study Design: Controlled laboratory study. Methods: Supraspinatus muscle samples were collected from 26 patients between the ages of 42 and 76 years with partial- or full-thickness rotator cuff tears. FAPs were quantified using fluorescence-activated cell sorting. Gene expression analysis was performed across a custom 96-gene panel using NanoString. In vitro differentiation assays of FAPs were conducted using adipogenic, fibrogenic, and beige-inducing (amibegron-treated) media, and quantitative polymerase chain reaction was used to assess gene expression differences between adipogenic and amibegron media conditions. Multivariable linear regressions were performed using Stata to independently analyze the effects of age and rotator cuff tear size on FAP number, differentiation, and gene expression. Results: Increasing age and tear size were independently correlated with increased FAP number (βage = 0.21, P = .03; βtear size = 3.86, P = .05). There was no clear association between age and gene expression of freshly sorted FAPs. Under adipogenic and fibrogenic media conditions, increasing age and tear size were independently associated with increased adipogenic and fibrogenic differentiation of FAPs. Under amibegron treatment conditions, age positively correlated with increased beige differentiation (β = 1.03; P < .0001), while increasing tear size showed a trend toward decreased beige differentiation (β = −4.87; P = .1). When gene expression patterns between adipogenic and amibegron media conditions were compared, larger tear size strongly inhibited beige gene expression, while advanced age did not. Conclusion: Patient age and rotator cuff tear size independently regulated FAP number, differentiation, and gene expression. Age and tear size were positively correlated with increased FAP number and fibrogenic/adipogenic differentiation. Advancing patient age did not limit FAP beige differentiation and gene expression, while increasing rotator cuff tear size strongly inhibited these processes.

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