title: Supraspinatus tendon overuse results in degenerative changes to tendon insertion region and adjacent humeral cartilage in a rat model.
abstract: The etiology of rotator cuff tendon overuse injuries is still not well understood. Furthermore, how this overuse injury impacts other components of the glenohumeral joint, including nearby articular cartilage, is also unclear. Therefore, this study sought to better understand the time course of tendon protease activity in a rat model of supraspinatus overuse, as well as determine effects of 10 weeks of overuse on humeral head articular cartilage. For these studies, multiplex gelatin zymography was used to characterize protease activity profiles in tendon and cartilage, while histological scoring/mechanical testing and micro-computed tomography (μCT) imaging were used to quantify structural damage in the supraspinatus tendon insertion and humeral articular cartilage, respectively. Histological scoring of supraspinatus tendon insertions revealed tendinopathic cellular and collagen fiber changes after 10 weeks of overuse when compared to controls, while mechanical testing revealed no significant differences between tensile moduli (overuse: 24.5 ± 11.5 MPa; control: 16.3 ± 8.7 MPa). EPIC-μCT imaging on humeral articular cartilage demonstrated significant cartilage thinning (overuse: 119.6 ± 6.34 μm; control: 195.4 ± 13.4μm), decreased proteoglycan content (overuse: 2.1 ± 0.18 cm-1; control: 1.65 ± 0.14 cm-1), and increased subchondral bone thickness (overuse: 216.2 ± 10.9 μm; control: 192 ± 17.8μm) in the overuse animals. Zymography results showed no significant upregulation of cathepsins or matrix metalloproteinases in tendon or cartilage at 2 or 10 weeks of overuse compared to controls. These results have further elucidated timing of protease activity over 10 weeks and suggest that damage occurs to other tissues in addition to the supraspinatus tendon in this overuse injury model. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1910-1918, 2017.
authors.affiliation: W.H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 313 Ferst Drive, Atlanta, Georgia 30332.
authors.forename: Akia N
authors.initials: AN
authors.lastname: Parks
authors.affiliation: W.H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 313 Ferst Drive, Atlanta, Georgia 30332.
authors.forename: Jennifer
authors.initials: J
authors.lastname: McFaline-Figueroa
authors.affiliation: W.H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 313 Ferst Drive, Atlanta, Georgia 30332.
authors.forename: Anne
authors.initials: A
authors.lastname: Coogan
authors.affiliation: W.H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 313 Ferst Drive, Atlanta, Georgia 30332.
authors.forename: Emma
authors.initials: E
authors.lastname: Poe-Yamagata
authors.affiliation: Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, 315 Ferst Drive, Atlanta, Georgia 30332.|George Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 801 Ferst Drive, Atlanta, Georgia 30332.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Guldberg
authors.affiliation: W.H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 313 Ferst Drive, Atlanta, Georgia 30332.|Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, 315 Ferst Drive, Atlanta, Georgia 30332.
authors.forename: Manu O
authors.initials: MO
authors.lastname: Platt
authors.affiliation: W.H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 313 Ferst Drive, Atlanta, Georgia 30332.|Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, 315 Ferst Drive, Atlanta, Georgia 30332.
authors.forename: Johnna S
authors.initials: JS
authors.lastname: Temenoff
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000000981:diagnostic imaging / Q000201:enzymology / Q000473:pathology*; D002403:Cathepsins / Q000378:metabolism; D012090:Cumulative Trauma Disorders / Q000000981:diagnostic imaging / Q000201:enzymology / Q000473:pathology*; D004195:Disease Models, Animal; D008297:Male; D020782:Matrix Metalloproteinases / Q000378:metabolism; D020303:Rats, Inbred Dahl; D017006:Rotator Cuff / Q000000981:diagnostic imaging / Q000201:enzymology / Q000473:pathology*; D000070636:Rotator Cuff Injuries / Q000000981:diagnostic imaging / Q000201:enzymology / Q000473:pathology*; D012785:Shoulder Joint / Q000000981:diagnostic imaging / Q000201:enzymology / Q000473:pathology*; D055114:X-Ray Microtomography
chemical_list: D002403:Cathepsins; D020782:Matrix Metalloproteinases
keywords: cartilage; micro-computed tomography; overuse injury; supraspinatus tendon; zymography