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  • 1
    In: Acta Biomaterialia, Elsevier BV, Vol. 70 ( 2018-04), p. 165-176
    Type of Medium: Online Resource
    ISSN: 1742-7061
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2018
    detail.hit.zdb_id: 2173841-5
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    Wiley ; 2022
    In:  Journal of Orthopaedic Research Vol. 40, No. 4 ( 2022-04), p. 977-986
    In: Journal of Orthopaedic Research, Wiley, Vol. 40, No. 4 ( 2022-04), p. 977-986
    Abstract: Rotator cuff disease pathogenesis is associated with intrinsic (e.g., age, joint laxity, muscle weakness) and extrinsic (e.g., mechanical load, fatigue) factors that lead to chronic degeneration of the cuff tissues. However, etiological studies are difficult to perform in patients due to the long duration of disease onset and progression. Therefore, the purpose of this study was to determine the effects of altered joint loading on the rotator cuff. Mice were subjected to one of three load‐dependent rotator cuff tendinopathy models: underuse loading, achieved by injecting botulinum toxin‐A into the supraspinatus muscle; overuse loading, achieved using downhill treadmill running; destabilization loading, achieved by surgical excision of the infraspinatus tendon. All models were compared to cage activity animals. Whole joint function was assessed longitudinally using gait analysis. Tissue‐scale structure and function were determined using microCT, tensile testing, and histology. The molecular response of the supraspinatus tendon and enthesis was determined by measuring the expression of 84 wound healing‐associated genes. Underuse and destabilization altered forepaw weight‐bearing, decreased tendon‐to‐bone attachment strength, decreased mineral density of the humeral epiphysis, and reduced tendon strength. Transcriptional activity of the underuse group returned to baseline levels by 4 weeks, while destabilization had significant upregulation of inflammation, growth factors, and extracellular matrix remodeling genes. Surprisingly, overuse activity caused changes in walking patterns, increased tendon stiffness, and primarily suppressed expression of wound healing‐related genes. In summary, the tendinopathy models demonstrated how divergent muscle loading can result in clinically relevant alterations in rotator cuff structure, function, and gene expression.
    Type of Medium: Online Resource
    ISSN: 0736-0266 , 1554-527X
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2022
    detail.hit.zdb_id: 2050452-4
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  • 3
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2018
    In:  Cardiovascular Engineering and Technology Vol. 9, No. 1 ( 2018-3), p. 105-119
    In: Cardiovascular Engineering and Technology, Springer Science and Business Media LLC, Vol. 9, No. 1 ( 2018-3), p. 105-119
    Type of Medium: Online Resource
    ISSN: 1869-408X , 1869-4098
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2018
    detail.hit.zdb_id: 2543111-0
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  • 4
    Online Resource
    Online Resource
    MyJove Corporation ; 2019
    In:  Journal of Visualized Experiments , No. 152 ( 2019-10-15)
    In: Journal of Visualized Experiments, MyJove Corporation, , No. 152 ( 2019-10-15)
    Type of Medium: Online Resource
    ISSN: 1940-087X
    Language: English
    Publisher: MyJove Corporation
    Publication Date: 2019
    detail.hit.zdb_id: 2259946-0
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  • 5
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    Online Resource
    SAGE Publications ; 2019
    In:  Orthopaedic Journal of Sports Medicine Vol. 7, No. 7_suppl5 ( 2019-07), p. 2325967119S0030-
    In: Orthopaedic Journal of Sports Medicine, SAGE Publications, Vol. 7, No. 7_suppl5 ( 2019-07), p. 2325967119S0030-
    Abstract: Partial patellar tendon tears (PPTTs) can be a frustrating injury for athletes and physicians. Determining the location and size of the PPTT are fundamental in understanding prognosis and selecting the most effective treatment. With recent enhancements in MRI quality, the size and dimensions of the tear can be more easily and accurately estimated. While some PPTTs respond to therapy, medication, bracing, biologic injections, and/or ultrasound procedures, other PPTTs in do not respond and require surgical intervention. The goal of this study is to correlate PPTT size and location to clinical outcomes, in order to create a classification system to help guide treatment decisions for athletes with PPTT. Methods: 112 athletic patients (range: 15-45 y/o, mean 23.9+7.2 y/o) who underwent knee MRI were included in this study. 85 of those patients (mean 24.9+8.1 y/o) presented with history and physical examination concerning for recalcitrant patellar tendonitis or suspicion of a partial patellar tendon tear. The other 27 athletic patients (mean 25.6+6.3 y/o) underwent MRI for other pathology and were included as age-matched controls. MR scans were evaluated for patellar tendon tear size, thickness, and location with respect to the entire patellar tendon. Descriptive statistics were used to evaluate tendon size and tear distributions. Pearson correlation, univariate regressions, and logistic regression were performed to correlate tendon geometry and tear sizes. Tear geometry variables were compared to patient outcome measures (return to previous activity level, surgical treatment) using t-tests. Results: 56 out of 85 symptomatic patients had partial patellar tendon tears. 91% of PPTTs involved the posterior and posteromedial region of the proximal patellar tendon (Figure 1). On axial MRI imaging, patients with PPTT had mean tendon thickness of 10 mm compared to 5.9 mm for athletes with no PPTT, including healthy controls (p 〈 .0001). There was a significant correlation between patellar tendon thickness and PPTT size (R=0.85, p 〈 0.0001). Logistic regression analysis showed that athletes with patellar tendon thickness above 7.45 mm are likely to have PPTTs (100% sensitivity). Tear distributions according to MRI grading are shown in Table 1. 11 out of 56 patients underwent surgery for PPTT. All 11 of these patients had tear sizes on axial images 〉 50% of tendon thickness (mean thickness of tear 6.3 mm). Logistic regression showed that patellar tendon thickness 〉 8.8 mm, and/or tear size 〉 55% correlated with surgical intervention. Five of the surgical patients did not make a return to sport at the same level. No patient in this series had surgery for tear thickness less than 4.5 mm. Basketball, track and field and soccer were the most common sports involved in the study. Conclusion: PPTTs are located posterior/posteromedially in the proximal patellar tendon. The most sensitive metric for PPTTs are patellar tendon thickness (anterior to posterior), where thickness more than 8.8 mm is strongly predictive of having a partial tear in the tendon. Athletes with greater than a 55% tear thickness on axial MRI imaging or with a tear measuring more than 4.5 mm on axial cuts are less likely to respond to non-operative treatment. Tracking thickness changes on axial views, specifically in the posterior/posteromedial region, may predict effectiveness of non-operative therapy. [Table: see text][Figure: see text]
    Type of Medium: Online Resource
    ISSN: 2325-9671 , 2325-9671
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2019
    detail.hit.zdb_id: 2706251-X
    SSG: 31
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  • 6
    In: Science Advances, American Association for the Advancement of Science (AAAS), Vol. 7, No. 48 ( 2021-11-26)
    Abstract: Architectured materials offer tailored mechanical properties but are limited in engineering applications due to challenges in maintaining toughness across their attachments. The enthesis connects tendon and bone, two vastly different architectured materials, and exhibits toughness across a wide range of loadings. Understanding the mechanisms by which this is achieved could inform the development of engineered attachments. Integrating experiments, simulations, and previously unexplored imaging that enabled simultaneous observation of mineralized and unmineralized tissues, we identified putative mechanisms of enthesis toughening in a mouse model and then manipulated these mechanisms via in vivo control of mineralization and architecture. Imaging uncovered a fibrous architecture within the enthesis that controls trade-offs between strength and toughness. In vivo models of pathology revealed architectural adaptations that optimize these trade-offs through cross-scale mechanisms including nanoscale protein denaturation, milliscale load-sharing, and macroscale energy absorption. Results suggest strategies for optimizing architecture for tough bimaterial attachments in medicine and engineering.
    Type of Medium: Online Resource
    ISSN: 2375-2548
    Language: English
    Publisher: American Association for the Advancement of Science (AAAS)
    Publication Date: 2021
    detail.hit.zdb_id: 2810933-8
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  • 7
    Online Resource
    Online Resource
    SAGE Publications ; 2020
    In:  The American Journal of Sports Medicine Vol. 48, No. 2 ( 2020-02), p. 359-369
    In: The American Journal of Sports Medicine, SAGE Publications, Vol. 48, No. 2 ( 2020-02), p. 359-369
    Abstract: Patellar tendinopathy is an overuse injury of the patellar tendon frequently affecting athletes involved in jumping sports. The tendinopathy may progress to partial patellar tendon tears (PPTTs). Current classifications of patellar tendinopathy are based on symptoms and do not provide satisfactory evidence-based treatment guidelines. Purpose: To define the relationship between PPTT characteristics and treatment guidelines, as well as to develop a magnetic resonance imaging (MRI)–based classification system for partial patellar tendon injuries. Study Design: Cohort study (prognosis); Level of evidence, 2. Methods: MRI characteristics and clinical treatment outcomes were retrospectively reviewed for 85 patients with patellar tendinopathy, as well as 86 physically active control participants who underwent MRI of the knee for other conditions. A total of 56 patients had a PPTT and underwent further evaluation for tear size and location. The relationship between tear characteristics and clinical outcome was defined with use of statistical comparisons and univariate and logistic regression models. Results: Of the 85 patients, 56 had partial-thickness patellar tendon tears. Of these tears, 91% involved the posterior and posteromedial regions of the proximal tendon. On axial MRI views, patients with a partial tear had a mean tendon thickness of 10 mm, as compared with 6.2 mm for those without ( P 〈 .001). Eleven patients underwent surgery for their partial-thickness tear. All of these patients had a tear 〉 50% of tendon thickness (median thickness of tear, 10.3 mm) on axial views. Logistic regression showed that tendon thickness 〉 8.8 mm correlated with the presence of a partial tear, while tendon thickness 〉 11.45 mm and tear thickness 〉 55.7% predicted surgical management. Conclusion: Partial-thickness tears are located posterior or posteromedially in the proximal patellar tendon. The most sensitive predictor for detecting the presence of a partial tear was patellar tendon thickness, in which thickness 〉 8.8 mm was strongly correlated with a tear of the tendon. Tracking thickness changes on axial MRI may predict the effectiveness of nonoperative therapy: athletes with patellar tendon thickness 〉 11.5 mm and/or 〉 50% tear thickness on axial MRI were less likely to improve with nonoperative treatment. A novel proposed classification system for partial tears, the Popkin-Golman classification, can be used to guide treatment decisions for these patients.
    Type of Medium: Online Resource
    ISSN: 0363-5465 , 1552-3365
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2020
    detail.hit.zdb_id: 2063945-4
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  • 8
    Online Resource
    Online Resource
    The Royal Society ; 2021
    In:  Journal of The Royal Society Interface Vol. 18, No. 185 ( 2021-12)
    In: Journal of The Royal Society Interface, The Royal Society, Vol. 18, No. 185 ( 2021-12)
    Abstract: Tendons of the body differ dramatically in their function, mechanics and range of motion, but all connect to bone via an enthesis. Effective force transfer at the enthesis enables joint stability and mobility, with strength and stiffness arising from a fibrous architecture. However, how enthesis toughness arises across tendons with diverse loading orientations remains unclear. To study this, we performed simultaneous imaging of the bone and tendon in entheses that represent the range of tendon-to-bone insertions and extended a mathematical model to account for variations in insertion and bone geometry. We tested the hypothesis that toughness, across a range of tendon entheses, could be explained by differences observed in interactions between fibre architecture and bone architecture. In the model, toughness arose from fibre reorientation, recruitment and rupture, mediated by interactions between fibres at the enthesis and the bony ridge abutting it. When applied to tendons sometimes characterized as either energy-storing or positional, the model predicted that entheses of the former prioritize toughness over strength, while those of the latter prioritize consistent stiffness across loading directions. Results provide insight into techniques for surgical repair of tendon-to-bone attachments, and more broadly into mechanisms for the attachment of highly dissimilar materials.
    Type of Medium: Online Resource
    ISSN: 1742-5662
    Language: English
    Publisher: The Royal Society
    Publication Date: 2021
    detail.hit.zdb_id: 2156283-0
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  • 9
    Online Resource
    Online Resource
    SAGE Publications ; 2021
    In:  The American Journal of Sports Medicine Vol. 49, No. 3 ( 2021-03), p. 780-789
    In: The American Journal of Sports Medicine, SAGE Publications, Vol. 49, No. 3 ( 2021-03), p. 780-789
    Abstract: More than 450,000 rotator cuff repairs are performed annually, yet healing of tendon to bone often fails. This failure is rooted in the fibrovascular healing response, which does not regenerate the native attachment site. Better healing outcomes may be achieved by targeting inflammation during the early period after repair. Rather than broad inhibition of inflammation, which may impair healing, the current study utilized a molecularly targeted approach to suppress IKKβ, shutting down only the inflammatory arm of the nuclear factor κB (NF-κB) signaling pathway. Purpose: To evaluate the therapeutic potential of IKKβ inhibition in a clinically relevant model of rat rotator cuff repair. Study Design: Controlled laboratory study. Methods: After validating the efficacy of the IKKβ inhibitor in vitro, it was administered orally once a day for 7 days after surgery in a rat rotator cuff repair model. The effect of treatment on reducing inflammation and improving repair quality was evaluated after 3 days and 2, 4, and 8 weeks of healing, using gene expression, biomechanics, bone morphometry, and histology. Results: Inhibition of IKKβ attenuated cytokine and chemokine production in vitro, demonstrating the potential for this inhibitor to reduce inflammation in vivo. Oral treatment with IKKβ inhibitor reduced NF-κB target gene expression by up to 80% compared with a nontreated group at day 3, with a subset of these genes suppressed through 14 days. Furthermore, the IKKβ inhibitor led to enhanced tenogenesis and extracellular matrix production, as demonstrated by gene expression and histological analyses. At 4 weeks, inhibitor treatment led to increased toughness, no effects on failure load and strength, and decreases in stiffness and modulus when compared with vehicle control. At 8 weeks, IKKβ inhibitor treatment led to increased toughness, failure load, and strength compared with control animals. IKKβ inhibitor treatment prevented the bone loss near the tendon attachment that occurred in repairs in control. Conclusion: Pharmacological inhibition of IKKβ successfully suppressed excessive inflammation and enhanced tendon-to-bone healing after rotator cuff repair in a rat model. Clinical Relevance: The NF-κB pathway is a promising target for enhancing outcomes after rotator cuff repair.
    Type of Medium: Online Resource
    ISSN: 0363-5465 , 1552-3365
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2021
    detail.hit.zdb_id: 2063945-4
    SSG: 31
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  • 10
    Online Resource
    Online Resource
    American Association for the Advancement of Science (AAAS) ; 2019
    In:  Science Translational Medicine Vol. 11, No. 481 ( 2019-02-27)
    In: Science Translational Medicine, American Association for the Advancement of Science (AAAS), Vol. 11, No. 481 ( 2019-02-27)
    Abstract: Tendon disorders represent the most common musculoskeletal complaint for which patients seek medical attention; inflammation drives tendon degeneration before tearing and impairs healing after repair. Clinical evidence has implicated the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway as a correlate of pain-free return to function after surgical repair. However, it is currently unknown whether this response is a reaction to or a driver of pathology. Therefore, we aimed to understand the clinically relevant involvement of the NF-κB pathway in tendinopathy, to determine its potential causative roles in tendon degeneration, and to test its potential as a therapeutic candidate. Transcriptional profiling of early rotator cuff tendinopathy identified increases in NF-κB signaling, including increased expression of the regulatory serine kinase subunit IKKβ, which plays an essential role in inflammation. Using cre-mediated overexpression of IKKβ in tendon fibroblasts, we observed degeneration of mouse rotator cuff tendons and the adjacent humeral head. These changes were associated with increases in proinflammatory cytokines and innate immune cells within the joint. Conversely, genetic deletion of IKKβ in tendon fibroblasts partially protected mice from chronic overuse–induced tendinopathy. Furthermore, conditional knockout of IKKβ improved outcomes after surgical repair, whereas overexpression impaired tendon healing. Accordingly, targeting of the IKKβ/NF-κB pathway in tendon stromal cells may offer previously unidentified therapeutic approaches in the management of human tendon disorders.
    Type of Medium: Online Resource
    ISSN: 1946-6234 , 1946-6242
    Language: English
    Publisher: American Association for the Advancement of Science (AAAS)
    Publication Date: 2019
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