Elsevier

Foot and Ankle Surgery

Volume 20, Issue 3, September 2014, Pages 154-159
Foot and Ankle Surgery

Review
The pathogenesis of Achilles tendinopathy: A systematic review

https://doi.org/10.1016/j.fas.2014.02.010Get rights and content

Abstract

Achilles tendinopathy is a degenerative, not an inflammatory, condition. It is prevalent in athletes involved in running sports.

A systematic literature review on Achilles tendon tendinopathy has been performed according to the intrinsic (age, sex, body weight, tendon temperature, systemic diseases, muscle strength, flexibility, previous injuries and anatomical variants, genetic predisposition and blood supply) and extrinsic risk factors (drugs and overuse), which can cause tendon suffering and degeneration. Different theories have been found: Neurogenic, Angiogenic, Impingement and “Iceberg” Hypotheses.

Multiple databases were utilized for articles published between 1964 and 2013.

The different hypothesis were analyzed, differently considering those concerning the pathogenesis of tendinopathy and those concerning the etiology of complaints in patients.

This review of the literature demonstrates the heterogeneity of Achilles tendinopathy pathogenesis. Various risk factors have been identified and have shown an interaction between them such as genes, age, circulating and local cytokine production, sex, biomechanics and body composition.

Introduction

The Achilles tendon is one of the most frequently injured tendons in the human body despite its strength [1]: it not only is the commonest tendon to rupture but also, along with the patellar tendon, it represents one of the two tendons most frequently impaired as a result of overuse [2]. Overuse is by definition a repetitive strain acting on a tendon, so that it can no longer endure stress and tension, but other factors may also play a role: the non-athletic population can be frequently affected [3], 30% of patients referred, do not regularly participate in sport [4]. Patients with Achilles tendinopathy commonly refers to pain in the tendon during initial loading, subsiding with continued activity; as the condition becomes chronic, pain can be persistent, resulting in activity curtailment or cessation [5], [6]. Infact Maffulli et al. [7] recently defined Achilles tendinopathy as a clinical syndrome characterized by three elements, pain, swelling and functional impairment, corresponding to the histological pattern of “tendinosis”, a term that indicates a degenerative non-inflammatory process with a disorganized collagen structure. However, it must be kept in mind that since up to 34% of asymptomatic tendons show histopathological changes [8]: this finding leads to suppose that the intratendinous degenerative changes may not be directly the cause of pain. So overuse is considered to induce the condition but the etiology and pathogenesis have not yet been scientifically clarified; the same is for the source of pain and the background of the pain mechanisms. Many different explanations have been raised and consequently the range of conservative and surgical treatment options is actually very wide [8]: a summary of the current hypotheses is provided, analyzing separately those concerning the pathogenesis of tendinopathy and those concerning the etiology of complaint in patients.

Section snippets

Materials and methods

Prisma guidelines were followed for this systematic review

Multiple databases, as PubMed, Google Scholar, Academic Search Complete, and Health and Wellness Resource Center, were searched for articles published between 1964 and 2013 concerning informations about the etiology of Achilles tendinopathy using the following search filter: “Achilles tendinopathy” and “Achilles pathogenesis” that identified a total of 480 articles dated from 1967 to 2013. The articles were combined into EndNote and

Etiology of intratendinous degenerative changes

It is widely acknowledged that causes of intratendinous changes could be divided into intrinsic and extrinsic factors; extrinsic factors play a major role in the acute lesions of the Achilles tendon, while most commonly will be a combination of both extrinsic and intrinsic factors in chronic tendinopathy [9].

According to the intrinsic risk factors, 68 articles describe the various risk factors involved [8], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24]

Discussion

The pathogenesis pathways of Achilles tendinopathy is heterogeneous (Fig. 1). Various risk factors have been identified: the aim of their identification is to develop and implement prevention strategies, since the extent of Achilles tendon injuries calls for preventive measures [39].

The highest incidence of Achilles tendinopathy is usually reported to occur in middle-age people (30–55 years old) [13]. Age is commonly associated with increased prevalence of degenerative changes, such as

Conclusions

In summary it should be kept in mind that, although loading history and individual factors may influence the onset and amount of tendon pathology, these are not generally considered when developing a treatment plan for painful tendons [138]. The goal of treatment of patients with chronic Achilles tendinopathy is to relieve pain. According to the finding that inflammation plays a role in the early phases of the disease [94] non-steroidal anti-inflammatory drugs and steroids may be beneficial,

Conflict of interest

None

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