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Exposure-dependent increases in IL-1beta, substance P, CTGF, and tendinosis in flexor digitorum tendons with upper extremity repetitive strain injury.

Authors
Fedorczyk-JM; Barr-AE; Rani-S; Gao-HG; Amin-M; Amin-S; Litvin-J; Barbe-MF
Source
J Orthop Res 2010 Mar; 28(3):298-307
NIOSHTIC No.
20036522
Abstract
Upper extremity tendinopathies are associated with performance of forceful repetitive tasks. We used our rat model of repetitive strain injury to study changes induced in forelimb flexor digitorum tendons. Rats were trained to perform a high repetition high force (HRHF) handle-pulling task (12 reaches/min at 60 +/- 5% maximum pulling force [MPF]), or a low repetition negligible force (LRNF) reaching and food retrieval task (three reaches/min at 5 +/- 5% MPF), for 2 h/day in 30 min sessions, 3 days/week for 3-12 weeks. Forelimb grip strength was tested. Flexor digitorum tendons were examined at midtendon at the level of the carpal tunnel for interleukin (IL)-1beta, neutrophil, and macrophage influx, Substance P, connective tissue growth factor (CTGF), and periostin-like factor (PLF) immunoexpression, and histopathological changes. In HRHF rats, grip strength progressively decreased, while IL-1beta levels progressively increased in the flexor digitorum peritendon (para- and epitendon combined) and endotendon with task performance. Macrophage invasion was evident in week 6 and 12 HRHF peritendon but not endotendon. Also in HRHF rats, Substance P immunoexpression increased in week 12 peritendon as did CTGF- and PLF-immunopositive fibroblasts, the increased fibroblasts contributing greatly to peritendon thickening. Endotendon collagen disorganization was evident in week 12 HRHF tendons. LRNF tendons did not differ from controls, even at 12 weeks. Thus, we observed exposure-dependent changes in flexor digitorum tendons within the carpal tunnel, including increased inflammation, nociceptor-related neuropeptide immunoexpression, and fibrotic histopathology, changes associated with grip strength decline.
Keywords
Animal-studies; Cellular-reactions; Cumulative-trauma; Cumulative-trauma-disorders; Ergonomics; Histopathology; Injuries; Laboratory-animals; Repetitive-work; Tissue-disorders; Author Keywords: cytokines; inflammation; flexor digitorum tendon; repetitive task; PLF; CTGF; WMSD
Contact
Mary F. Barbe, Department of Physical Therapy, Thomas Jefferson University, 130 South 9th Street, Philadelphia, Pennsylvania 19107
CODEN
JOREDR
Publication Date
20100301
Document Type
Journal Article
Email Address
mary.barbe@temple.edu
Funding Type
Grant
Fiscal Year
2010
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-R01-OH-003970
Issue of Publication
3
ISSN
0736-0266
Source Name
Journal of Orthopaedic Research
State
PA
Performing Organization
Temple University
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