Effects of tendon injury on uninjured regional tendons in the distal limb: An in-vivo study using an ovine tendinopathy model.

Albert S Tsang,Andrew J Dart,Christopher B Little,Leo B Jeffcott,Margaret M Smith,Sara A Biasutti,James H-C Wang

doi:10.1371/journal.pone.0215830

Albert S Tsang, Andrew J Dart + Show 5 more

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https://doi.org/10.1371/journal.pone.0215830

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Journal: PloS one	Publication Date: Apr 23, 2019
Citations: 10	License type: CC BY 4.0

Affiliation: University of Sydney, Royal North Shore Hospital

Abstract

Following injury to a tendon little is known about potential for pathology to develop in other regional tendons from overloading or altered function. The aim of this study was to investigate the gene expression and histopathological changes that occur 1) within the deep digital flexor tendon (DDFT) after injury to the superficial digital flexor tendon (SDFT) and 2) within the flexor tendons (SDFT and DDFT) after injury to the extensor tendons. Merino wethers [Ovis aries] (n = 18) were divided into three equal groups and underwent either partial transection of the SDFT, complete transection of the extensor tendons or were left as non-operated controls. Tendons were harvested and sampled regionally for gene expression (real time PCR) and histologic analysis eight weeks after surgery. Transection of the SDFT resulted in increased expression of collagen III, versican, biglycan, lumican and MMP1 (P<0.026 for all genes) within the DDFT. There was no effect of transecting the extensor tendons on the expression of any gene tested in either the SDFT or the DDFT. The DDFT had elevated histopathology scores induced by transection of the SDFT, eight weeks previously. There were minimal histological differences in either the SDFT or DDFT after transection of the extensor tendons. Transection of the SDFT results in a mild, subclinical tendinopathy within the DDFT with potential implications on treatment and rehabilitation of SDFT injuries. Injury to the extensor tendons has minimal measured effect on the SDFT or DDFT.

Highlights

Tendon injuries are a common problem in human and equine athletes [1,2,3]
No gross abnormalities were noted in the deep digital flexor tendon (DDFT) after partial transection of the superficial digital flexor tendon (SDFT) or the SDFT and DDFT after complete transection of the extensor tendons
Aspects of the tendinopathic changes observed in the SDFT, such as cellularity, collagen fibre malalignment and vascularity, did not appear to resolve over time and the authors considered that this pathology is likely to persist in the long term and have implications on the structure and function of the tendon [1, 18]

Summary

Introduction

Tendon injuries are a common problem in human and equine athletes [1,2,3]. They are the most common form of musculoskeletal injury in the horse and have been reported to account for up to 46% of all musculoskeletal injuries in athletic horses [4]. Due to the limited amount of soft tissue on the distal limb of horses, traumatic lacerations often involve the underlying tendons and bones [6, 7]

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