Functional Outcomes After Imaging- and Orthopedic Test-Guided Evaluation of Shoulder Disorders: Systematic Review and Meta-Analysis.

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Abstract

Conflict of interest statement: The authors declare no conflicts of interest. 11. J Orthop Res. 2022 Apr;40(4):977-986. doi: 10.1002/jor.25113. Epub 2021 Jun 13. The role of loading in murine models of rotator cuff disease. Abraham AC(1), Fang F(2), Golman M(3), Oikonomou P(3), Thomopoulos S(2)(3). Author information: (1)Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, Michigan, USA. (2)Department of Orthopaedic Surgery, Columbia University Irving Medical Center, New York, New York, USA. (3)Department of Biomedical Engineering, Columbia University, New York, New York, USA. 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. © 2021 Orthopaedic Research Society. Published by Wiley Periodicals LLC. DOI: 10.1002/jor.25113 PMCID: PMC8639823