Functional anatomy, histology and biomechanics of the human Achilles tendon - A comprehensive review.

OBJECTIVES: The aim of this study was to provide a comprehensive overview of the anatomical, histological, and biomechanical aspects of the Achilles tendon. METHODS: A comprehensive search on the relevant aspects of the Achilles tendon was performed through the main electronic databases up to October 2019. Data from relevant articles was gathered, analyzed, and included in this review. RESULTS: This review outlines crucial topics on the anatomy, histology, and biomechanics of the Achilles tendon. The first part, focusing on clinically relevant anatomy, describes the tendon as well as its surrounding structures. Particular focus is made on anatomical divisions. The second part discusses histologic features, contrasting normal morphology with pathologic changes. The third part summarizes various biomechanical aspects of the Achilles tendon, especially those crucial to understanding the key functionality of the tendon. These components make up this review aimed to aggregate relevant information regarding the Achilles tendon to provide an up to date assessment of current knowledge, as well as visions for future directions of Achilles tendon research. CONCLUSIONS: Comprehensive knowledge regarding the Achilles tendon is crucial whilst rates of injury continue to be relevant. A proper understanding of the anatomy, histology, and biomechanics is vital for clinical perception as well as establishing the direction of further research in new therapies.

TIMP-1 association with collagen type I overproduction in hereditary gingival fibromatosis.

OBJECTIVES: To investigate the processes associated with the excessive production of collagen I in hereditary gingival fibromatosis (HGF). MATERIALS AND METHODS: Three HGF subjects and five controls were enrolled in the study. Histomorphological and immunohistological analyses were performed on gingival tissues. The expression of heat-shock protein 47 (HSP47), collagen I, transforming growth factor-ß1 (TGF-ß1), connective tissue growth factor (CTGF), matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) by gingival fibroblasts isolated from HGF and controls was analysed using qRT-PCR, Western blotting and ELISA. RESULTS: Considerable accumulation of fibrotic fibrils and increased synthesis of HSP47 were noted in HGF gingival tissues. The synthesis of collagen I, HSP47, TGF-ß1, CTGF and TIMP-1 was significantly elevated in HGF gingival fibroblasts compared with controls, while the production of MMP-1 was decreased. CONCLUSIONS: We report that fibrosis in HGF gingival tissues is associated with increased synthesis of HSP47. This finding was confirmed by an in vitro study, where excessive production of collagen I was associated with increased synthesis of HSP47, TGF-ß1 and CTGF by HGF gingival fibroblasts. Moreover, the shift in the TIMP-1/MMP-1 ratio identifies increased synthesis of TIMP-1 as one of the processes associated with collagen I overproduction in HGF fibroblasts.