Tendon disorders are common and confer a large socioeconomic burden. This Review discusses the role of inflammatory mechanisms in tendon homeostasis and resolution of tendon damage, which are crucial to consider in developing novel therapeutics for tendinopathies. Tendinopathy is a multifactorial spectrum of tendon disorders that affects different anatomical sites and is characterized by activity-related tendon pain. These disorders are common, account for a high proportion (∼30%) of referrals to musculoskeletal practitioners and confer a large socioeconomic burden of disease. Our incomplete understanding of the mechanisms underpinning tendon pathophysiology continues to hamper the development of targeted therapies, which have been successful in other areas of musculoskeletal medicine. Debate remains among clinicians about the role of an inflammatory process in tendinopathy owing to a lack of clinical correlation. The advent of modern molecular techniques has highlighted the presence of immune cells and inflammatory mechanisms throughout the spectrum of tendinopathy in both animal and human models of disease. Key inflammatory mediators — such as cytokines, nitric oxide, prostaglandins and lipoxins — play crucial parts in modulating changes in the extracellular matrix within tendinopathy. Understanding the links between inflammatory mechanisms, tendon homeostasis and resolution of tendon damage will be crucial in developing novel therapeutics for human tendon disease.

Inflammatory mechanisms in tendinopathy – towards translation

Background:The incidence of distal biceps tendon ruptures was studied more than 10 years ago in a small patient cohort. Recent diagnostic advancements have improved the ability to detect this rare injury.Hypothesis:The incidence of distal biceps tendon ruptures will be significantly greater than previously reported.Study Design:Descriptive epidemiologic study.Methods:A query of the PearlDiver Technologies national database containing public and private insurance patients was used to estimate the national incidence of distal biceps tendon ruptures in the United States. A retrospective chart review of our local population identified demographic groups and risk factors that increased likelihood of injury.Results:The estimated national incidence of distal biceps tendon rupture was 2.55 per 100,000 patient-years. The local incidence was 5.35 per 100,000 patient-years. The mean and median ages of patients in our regional cohort were 46.3 and 46 years, respectively. Males composed the majority of the injured pop...

Distal Biceps Tendon Ruptures: An Epidemiological Analysis Using a Large Population Database

There is currently great interest in the use of Extracorporeal Shock Wave Therapy (ESWT) and in clarifying the mechanisms of action in tendon pathologies. The success rate ranges from 60% to 80% in epicondylitis, plantar fasciitis, cuff tendinitis, trocanteritis, Achilles tendinitis or jumper's knee. In contrast to urological treatments (lithotripsy), where shockwaves are used to disintegrate renal stones, in musculoskeletal treatments (orthotripsy), shockwaves are not being used to disintegrate tissues, but rather to microscopically cause interstitial and extracellular biological responses and tissue regeneration. The researchers are interesting to investigate the biological effects which support the clinical successes. Some authors speculated that shockwaves relieve pain in insertional tendinopathy by hyper-stimulation analgesia. Many recent studies demonstrated the modulations of shockwave treatment including neovascularization, differentiation of mesenchymal stem cells and local release of angiogenetic factors. The experimental findings confirm that ESWT decrease the expression of high levels of inflammatory mediators (matrix metalloproteinases and inter-leukins). Therefore, ESWT produces a regenerative and tissue-repairing effect in musculoskeletal tissues, not merely a mechanical disintegrative effect as generally before assumed. Based on the encouraging results of clinical and experimental studies, the potential of ESWT appears to be emerging. The promising outcome after this non-invasive treatment option in tendinitis care justifies the indication of shockwave therapy. Further studies have to be performed in order or determine optimum treatment parameters and will bring about an improvement in accordance with evidence-based medicine. Finally, meta-analysis studies are necessary to demonstrate the efficacy and safety of ESWT in treating tendinopathies.

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The biological effects of extracorporeal shock wave therapy (eswt) on tendon tissue.

Background: Achilles tendinopathy (AT) is a common condition, causing considerable morbidity in athletes and non-athletes alike. Conservative or physical therapies are accepted as first-line management of AT; however, despite a growing volume of research, there remains a lack of high quality studies evaluating their efficacy. Previous systematic reviews provide preliminary evidence for non-surgical interventions for AT, but lack key quality components as outlined in the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) Statement. The aim of this study was to conduct a systematic review and meta-analysis (where possible) of the evidence for physical therapies for AT management. Methods: A comprehensive strategy was used to search 11 electronic databases from inception to September 2011. Search terms included Achilles, tendinopathy, pain, physical therapies, electrotherapy and exercise (English language full-text publications, human studies). Reference lists of eligible papers were hand-searched. Randomised controlled trials (RCTs) were included if they evaluated at least one non-pharmacological, non-surgical intervention for AT using at least one outcome of pain and/or function. Two independent reviewers screened 2852 search results, identifying 23 suitable studies, and assessed methodological quality and risk of bias using a modified PEDro scale. Effect size calculation and meta-analyses were based on fixed and random effects models respectively. Results: Methodological quality ranged from 2 to 12 (/14). Four studies were excluded due to high risk of bias, leaving 19 studies, the majority of which evaluated midportion AT. Effect sizes from individual RCTs support the use of eccentric exercise. Meta-analyses identified significant effects favouring the addition of laser therapy to eccentric exercise at 12 weeks (pain VAS: standardised mean difference −0.59, 95% confidence interval −1.11 to −0.07), as well as no differences in effect between eccentric exercise and shock wave therapy at 16 weeks (VISA-A:–0.55,–2.21 to 1.11). Pooled data did not support the addition of night splints to eccentric exercise at 12 weeks (VISA-A:–0.35,–1.44 to 0.74). Limited evidence from an individual RCT suggests microcurrent therapy to be an effective intervention. Conclusions: Practitioners can consider eccentric exercise as an initial intervention for AT, with the addition of laser therapy as appropriate. Shock wave therapy may represent an effective alternative. High-quality RCTs following CONSORT guidelines are required to further evaluate the efficacy of physical therapies and determine optimal clinical pathways for AT.

/pdf/physical-therapies-for-achilles-tendinopathy-systematic-22w203si7y.pdf

Physical therapies for Achilles tendinopathy: systematic review and meta-analysis

In calcific tendinopathy (CT), calcium deposits in the substance of the tendon, with chronic activity-related pain, tenderness, localized edema and various degrees of decreased range of motion. CT is particularly common in the rotator cuff, and supraspinatus, Achilles and patellar tendons. The presence of calcific deposits may worsen the clinical manifestations of tendinopathy with an increase in rupture rate, slower recovery times and a higher frequency of post-operative complications. The aetiopathogenesis of CT is still controversial, but seems to be the result of an active cell-mediated process and a localized attempt of the tendon to compensate the original decreased stiffness. Tendon healing includes many sequential processes, and disturbances at different stages of healing may lead to different combinations of histopathological changes, diverting the normal healing processes to an abnormal pathway. In this review, we discuss the theories of pathogenesis behind CT. Better understanding of the pathogenesis is essential for development of effective treatment modalities and for improvement of clinical outcomes.

/pdf/physiopathology-of-intratendinous-calcific-deposition-3vy529bx37.pdf

Physiopathology of intratendinous calcific deposition

Overuse tendinopathies are a common cause of pain and disability in athletes. According to histological findings, it is a failed healing response to overuse tendon injury. In obesity, macrophages and mast cells migrate to adipose tissue, and the resulting decreased availability of immune circulating cells should be responsible for less effective immune responses to acute tendon injury. In diabetic patients, free glucose molecules attach to collagen, alter collagen solubility, increase resistance to enzymatic degradation, and impair cross linking, contributing to the subsequent development of chronic tendinopathy secondary to a failed healing response to a tendon insult. Prolonged systemic, low-grade inflammation and impaired insulin sensitivity act as a risk factor for a failed healing response after an acute tendon insult, and predispose to the development of chronic overuse tendinopathies. Further studies may reveal novel therapeutic treatment approaches.

https://journals.sagepub.com/doi/pdf/10.1177/03946320110241S209

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Papers

Tendinopathy and inflammation: some truths.