Types and epidemiology of tendinopathy

Anatomical study of paratenons and fascia lata connections in the posteromedial knee region

INTRODUCTION

In the last decade, fascia research increased significantly in various aspects such as anatomical and biomechanical features related to epimuscular force transmission.

METHODS

The present anatomic study focuses on macroscopic observations of the potential gracilis and semitendinosus paratenons, as well as fascial surroundings connections in the posteromedial knee region on 17 lower-limbs dissections.

RESULTS

The gracilis and semitendinosus expansions and paratenons were observed in all specimen and further connections with the fascia lata and crural fascia were demonstrated. Contrary to the previously described expansions connected to the tendons, we observed that the expansions were the edges of the paratenon tunnel and that the paratenon structure surrounded the overall muscle. Both paratenons of gracilis and semitendinosus were connected to the crural fascia and, respectively, to the sartorius fascia (part of the fascia lata), to the semimembranosus and the fascia lata. Furthermore, numerous connections between the fascia lata and the neighboring structures in the posteromedial knee region are described.

DISCUSSION-CONCLUSION

The present study describes for the first time gracilis and semitendinosus paratenons and other surrounding fascial connections. Such macroscopic observations may represent a new basis for further characterization of the myofascial pathway of epimuscular force transmission in the knee region.

Does Additional Dietary Supplementation Improve Physiotherapeutic Treatment Outcome in Tendinopathy? A Systematic Review and Meta-Analysis

A systematic review and meta-analysis of randomized controlled trials was performed to evaluate the effects of dietary supplements in addition to physiotherapeutic treatment on pain and functional outcomes. PubMed, The Cochrane Library, Web of Science, and Embase were searched from inception to November 2021 (Prospero registration: CRD42021291951). Studies were eligible if the interventions consisted of physiotherapeutic approaches that were combined with dietary supplementation and if they reported measures of pain and/or function. Six studies were included in the meta-analysis. Standardized mean differences (SMD) and 95% confidence intervals (CI) were calculated and analysed using a Review Manager software. Subgroup analysis was performed to explore possible associations between the study characteristics and the effectiveness of the intervention. Additional dietary supplementation during physiotherapeutic treatment significantly improved the reduction in pain score (SMD = −0.74, 95% CI, −1.37 to −0.10; p < 0.05), while it had no effect on functional outcomes (SMD = 0.29, 95% CI, 0.00 to 0.58; p > 0.05). This systematic review and meta-analysis suggests that additional nutritional interventions may improve physiotherapeutic treatment outcomes in the management of tendinopathies.

Exosomes from tendon derived stem cells promote tendon repair through miR-144-3p-regulated tenocyte proliferation and migration

BACKGROUND

Tendon derived stem cells (TDSCs) have proven to be effective in tendon repair by secreting paracrine factors, which modulate the function of resident cells and inflammatory process. Exosomes, which are secreted from cells to mediate intercellular communication, may be used to treat tendon injuries. Here, we aimed to determine the effects of exosomes from TDSCs (TDSC-Exos) on tendon repair and to explore the underlying mechanism by investigating the role of microRNAs (miRNAs).

METHODS

TDSC-Exos were isolated from TDSC conditioned medium. In vitro studies were performed to investigate the effects of TDSC-Exos on the proliferation, migration, cytoprotection, collagen production and tendon-specific markers expression in tenocytes. In order to determine the therapeutic effects of TDSC-Exos in vivo, we used a scaffold of photopolymerizable hyaluronic acid (p-HA) loaded with TDSC-Exos (pHA-TDSC-Exos) to treat tendon defects in the rat model. Subsequently, RNA sequencing and bioinformatic analyses were used to screen for enriched miRNAs in TDSC-Exos and predict target genes. The miRNA-target transcript interaction was confirmed by a dual-luciferase reporter assay system. In order to determine the role of candidate miRNA and its target gene in TDSC-Exos-regulated tendon repair, miRNA mimic and inhibitor were transfected into tenocytes to evaluate cell proliferation and migration.

RESULTS

Treatment with TDSC-Exos promoted proliferation, migration, type I collagen production and tendon-specific markers expression in tenocytes, and also protected tenocytes from oxidative stress and serum deprivation. The scaffold of pHA-TDSC-Exos could sever as a sustained release system to treat the rat model of tendon defects. In vivo study showed that TDSC-Exos promoted early healing of injured tendons. Rats treated with TDSC-Exos had better fiber arrangement and histological scores at the injury site. Besides, the injured tendons treated with TDSC-Exos had better performance in the biomechanical testing. Therefore, the pHA-TDSC-Exos scaffold proved to facilitate tendon repair in the rat model. miR-144-3p was enriched in TDSC-Exos and promoted tenocyte proliferation and migration via targeting AT-rich interactive domain 1A (ARID1A).

CONCLUSIONS

TDSC-Exos enhanced tenon repair through miR-144-3p-regulated tenocyte proliferation and migration. These results suggest that TDSC-Exos can serve as a promising strategy to treat tendon injuries.

Restorative and pain-relieving effects of fibroin in preclinical models of tendinopathy

The term tendinopathy indicates a wide spectrum of conditions characterized by alterations in tendon tissue homeostatic response and damage to the extracellular matrix. The current pharmacological approach involves the use of nonsteroidal anti-inflammatory drugs and corticosteroids often with unsatisfactory results, making essential the identification of new treatments. In this study, the pro-regenerative and protective effects of an aqueous fibroin solution (0.5-500 μg/mL) against glucose oxidase (GOx)-induced damage in rat tenocytes were investigated. Then, fibroin anti-hyperalgesic and protective actions were evaluated in two models of tendinopathy induced in rats by collagenase or carrageenan injection, respectively. In vitro, 5-10 μg/mL fibroin per se increased cell viability and reverted the morphological alterations caused by GOx (0.1 U/mL). Fibroin 10 μg/mL evoked proliferative signaling upregulating the expression of decorin, scleraxin, tenomodulin (p < 0.001), FGF-2, and tenascin-C (p < 0.01) genes. Fibroin enhanced the basal FGF-2 and MMP-9 protein concentrations and prevented their GOx-mediated decrease. Furthermore, fibroin positively modulated the production of collagen type I. In vivo, the peri-tendinous injection of fibroin (5 mg) reduced the development of spontaneous pain and hypersensitivity (p < 0.01) induced by the intra-tendinous injection of collagenase; the efficacy was comparable to that of triamcinolone. The pain-relieving action of fibroin (peri-tendinous) was confirmed in the model of tendinopathy induced by carrageenan (intra-tendinous) where this fibrous protein was also able to improve tendon matrix organization, normalizing the orientation of collagen fibers. In conclusion, the use of fibroin in tendinopathies is suggested taking advantage of its excellent mechanical properties, pain-relieving effects, and ability to promote tissue regeneration processes.

Bibliometric Study of Exercise and Tendinopathy Research from 2001 to 2020

Background

Tendinopathy is a tendon disease that often occurs in athletes. Many studies have revealed that exercise therapy is beneficial for the nonoperative management of tendinopathy. However, the general aspect bibliometric analysis of this global research topic associated with exercise and tendinopathy is lacking. The present study aimed to make a bibliometric analysis of worldwide development tendency and research hotspots in exercise and tendinopathy research from 2001 to 2020.

Material/Methods

Using the Web of Science, articles and reviews published between 2001 and 2020 were retrieved from the Science Citation Index Expanded database. CiteSpace was used to analyze the relationship among publications, countries, institutions, journals, authors, references, and keywords.

Results

In total, 857 articles were found in this study. Over the past 20 years, there was a marked increase in the number of publications. A total of 194 different scholarly journals were dedicated to the categories Sport Sciences, Orthopedics, and Rehabilitation. The USA and La Trobe University were the most prolific country and institution, respectively. The British Journal of Sports Medicine was the prominent journal for research on exercise and tendinopathy and had the most publications. The analysis of keywords showed that rehabilitation, rotator cuff tendinopathy, stiffness, and disability of individuals with tendinopathy had become the research focus in this field.

Conclusions

Bibliometric analysis provides a historical and scientific perspective on exercise and tendinopathy research, providing relevant researchers, funding agencies, and policymakers with valuable information to explore the current research status, hotspots, and new directions for future research.

Effects of focused ultrasound and dry needling on tendon mechanical properties

Tendon injuries are extremely common, resulting in mechanically weaker tendons that could lead to tendon rupture. Dry needling (DN) is widely used to manage pain and function after injury. However, DN is invasive and high inter-practitioner variability has led to mixed success rates. Focused ultrasound (fUS) is a non-invasive medical technology that directs ultrasound energy into a well-defined focal volume. fUS can induce thermal ablation or mechanical fractionation, with bioeffect type controlled through ultrasound parameters. Tendons must withstand high physiological loads, thus treatments maintaining tendon mechanical properties while promoting healing are needed. Our objective was to evaluate mechanical effects of DN and 3 fUS parameter sets, chosen to prioritize mechanical fractionation, on Achilles and supraspinatus tendons. Ex vivo rat Achilles and supraspinatus tendons (50 each) were divided into sham, DN, fUS-1, fUS-2, and fUS-3 (n = 10/group). Following treatment, tendons were mechanically tested. Elastic modulus of supraspinatus tendons treated with DN (126.64 ± 28.1 MPa) was lower than sham (153.02 ± 29.3 MPa; p = 0.0280). Stiffness and percent relaxation of tendons treated with DN (Achilles: 114.40 ± 31.6 N/mm; 49.10 ± 6.1%; supraspinatus: 109.53 ± 30.8 N/mm; 50.17 ± 7.6%) were lower (all p < 0.0334) than sham (Achilles: 141.34 ± 20.9 N/mm; 60.30 ± 7.7%; supraspinatus: 135.14 ± 30.2 N/mm; 60.85 ± 15.4%). Modulus of Achilles and supraspinatus tendons treated with fUS-1 (159.88 ± 25.7 MPa; 150.12 ± 22.0 MPa, respectively) were similar to sham (156.35 ± 23.0 MPa; 153.02 ± 29.3 MPa, respectively). These results suggest that fUS preserves mechanical properties better than DN, with fUS-1 performing better than fUS-2 and fUS-3. fUS should be studied further to fully understand its mechanical and healing effects to help evaluate fUS as an alternative, non-invasive treatment for tendon injuries.

Current understanding of the diagnosis and management of the tendinopathy: An update from the lab to the clinical practice

Tendinopathy is labeled by many authors as a troublesome, common pathology, present in up to 30% medical care consultations involving musculoskeletal conditions. Despite the lasting interest for addressing tendon pathology, current researchers agree that even the exact definition of the term tendinopathy is unclear. Tendinopathy is currently diagnosed as a clinical hypothesis based on the patient symptoms and physical context. One of the main goals of current clinical management is to personalize treatment approaches to adapt them to the many different needs of the population. Tendons are complex structures that unite muscles and bones with two main objectives: to transmit forces and storage and release energy. Regarding the tensile properties of the tendons, several authors argued that tendons have higher tensile strength compared with muscles, however, are considered less flexible. Tendinopathy is an accepted term which is used to indicated a variety of tissue conditions that appear in injured tendons and describes a non-rupture damage in the tendon or paratendon, which is intensified with mechanical loading Even when the pathoetiology of tendinopathy is unclear, there is a wide array of treatments available to treat and manage tendinopathy. Although tendinitis usually debuts with an inflammatory response, the majority of chronic tendinopathies do not present inflammation and so the choosing of treatment should vary depending on severity, compliance, pain and duration of symptoms. The purpose of this article is to review and provide an overview about the currently research of the tendon diagnosis, management and etiology.

The Effect of Age and Intrinsic Aerobic Exercise Capacity on the Expression of Inflammation and Remodeling Markers in Rat Achilles Tendons

Old age, adiposity, and metabolic disorders are known as risk factors for chronic tendinopathy, which is a common problem in both athletes and the general population. However, the importance of these influencing factors has not yet been well understood. This study investigated alterations in gene expression and histology of Achilles tendons of young (10 weeks) and old (100 weeks) rats bred for low (low capacity runners, LCR) and high (high capacity runners, HCR) intrinsic aerobic exercise capacity. In this rat model, LCR displayed a phenotype of reduced exercise capacity, higher body weight, and metabolic dysfunctions compared to HCR. We hypothesized that the risk factors for tendinopathy in old LCR could lead to more pronounced impairments in Achilles tendon tissue. In quantitative real-time PCR (qPCR), age-related downregulation of tenocyte markers e.g., tenomodulin, genes related to matrix modeling and remodeling (e.g., collagens, elastin, biglycan, fibronectin, tenascin C) as well as transforming growth factor beta 3 (Tgfb3) have been detected. Inflammation marker cyclooxygenase 2 (Cox2) was downregulated in old rats, while microsomal prostaglandin E synthase 2 (Ptges2) was upregulated in old HCR and old LCR. In all groups, interleukin 6 (Il6), interleukin 1 beta (Il1b), and tumor necrosis factor alpha (Tnfa) showed no significant alteration. In histological evaluation, tendons of old rats had fewer and more elongated tenocyte nuclei than young rats. Even though a higher content of glycosaminoglycans, a sign of degeneration, was found in old HCR and LCR, no further signs of tendinopathy were detectable in tendons of old rats by histological evaluation. Low intrinsic aerobic exercise capacity and the associated phenotype did not show significant effects on gene expression and tendon histology. These findings indicate that aging seems to play a prominent role in molecular and structural alterations of Achilles tendon tissue and suggests that other risk factors associated with intrinsic aerobic exercise capacity are less influential in this rat model.

Early Outcome of a Single Peri-Tendinous Hyaluronic Acid Injection for Mid-Portion Non-Insertional Achilles Tendinopathy - A Pilot Study

AIM

The aim of this study was to evaluate the efficacy and safety of a single, peri-tendinous injection of hyaluronic acid for mid-portion, non-insertional Achilles tendinopathy.

MATERIALS AND METHODS

A prospective, open labelled, single center, pilot study was conducted. All patients enrolled received a single peri-tendinous injection of Ostenil Tendon™ (40 mg/2 ml 2% HA with 0.5% mannitol). Outcome measures were Visual Analogue Scale (VAS) pain score and Manchester-Oxford Foot Questionnaire (MOxFQ) scores at 2 weeks and at final follow at 12 weeks. Any major and minor adverse effects were recorded. To assess change in VAS and MOxFQ scores, t test and Wilcoxon signed rank test were employed.

RESULTS

Seventeen patients were enrolled in this study with a mean follow-up of 12 weeks. Mean pre-injection VAS score was 9.38 cm (9-9.8), which significantly reduced post-injection to a mean score of 4.09 cm (2-8) at week-2 stage, and further improved to 3.01 cm (2-3.9) at the final follow-up (p < 0.0001). MOxFQ score showed a significant improvement from pre-injection value of 67.77 (63.03-72.55) to 31.18 (13-60) at week-2 stage, and further improved to 24.20 (15.73-32.67) at the final follow-up (p < 0.0001). The mean improvement from pre-injection to the final follow up was 43.57 (34.25-52.90). No adverse effects for injections were recorded.

CONCLUSION

This small series suggests an encouraging response of a single injection of HA as an effective and safe option for non-insertional Achilles tendinopathy.

Autoregulation in Resistance Training for Lower Limb Tendinopathy: A Potential Method for Addressing Individual Factors, Intervention Issues, and Inadequate Outcomes

Musculoskeletal disorders, such as tendinopathy, are placing an increasing burden on society and health systems. Tendinopathy accounts for up to 30% of musculoskeletal disorders, with a high incidence in athletes and the general population. Although resistance training has shown short-term effectiveness in the treatment of lower limb tendinopathy, more comprehensive exercise protocols and progression methods are required due to poor long-term outcomes. The most common resistance training protocols are predetermined and standardized, which presents significant limitations. Current standardized protocols do not adhere to scientific resistance training principles, consider individual factors, or take the importance of individualized training into account. Resistance training programs in case of tendinopathy are currently not achieving the required intensity and dosage, leading to high recurrence rates. Therefore, better methods for individualizing and progressing resistance training are required to improve outcomes. One potential method is autoregulation, which allows individuals to progress training at their own rate, taking individual factors into account. Despite the finding of their effectiveness in increasing the strength of healthy athletes, autoregulation methods have not been investigated in case of tendinopathy. The purpose of this narrative review was 3-fold: firstly, to give an overview and a critical analysis of the individual factors involved in tendinopathy and current resistance training protocols and their limitations. Secondly, to give an overview of the history, methods, and application of autoregulation strategies both in sports performance and physiotherapy. Finally, a theoretical adaptation of a current tendinopathy resistance training protocol using autoregulation methods is presented, providing an example of how the method could be implemented in clinical practice or future research.

Stem cell therapies in tendon-bone healing

Tendon-bone insertion injuries such as rotator cuff and anterior cruciate ligament injuries are currently highly common and severe. The key method of treating this kind of injury is the reconstruction operation. The success of this reconstructive process depends on the ability of the graft to incorporate into the bone. Recently, there has been substantial discussion about how to enhance the integration of tendon and bone through biological methods. Stem cells like bone marrow mesenchymal stem cells (MSCs), tendon stem/progenitor cells, synovium-derived MSCs, adipose-derived stem cells, or periosteum-derived periosteal stem cells can self-regenerate and potentially differentiate into different cell types, which have been widely used in tissue repair and regeneration. Thus, we concentrate in this review on the current circumstances of tendon-bone healing using stem cell therapy.

Numerical Analysis of the ACL, with Sprains of Different Degrees after Trauma

Nowadays, cruciate ligament injuries have increased in incidence, since practicing a sport or physical activity has become a trend in current societies. Although this lifestyle generates multiple benefits, as a consequence, injury has also increased. Due to its nature and complexity, the ligaments of the knee are those that are most frequently affected, mainly the ACL (anterior cruciate ligament). This tissue reacts to overexertion or movements out of range, either caused by the exercise itself or caused by trauma caused by the practice of physical activity, causing various degrees of sprain. Whatever the etiology of these injuries, they will require a therapy indicated for each degree of injury. This therapy initially entails immobilization of the affected area and later; physical therapy will be required to a lesser or greater degree. Commonly, in the physiotherapy of these injuries, rehabilitation exercises are prescribed, where the physiotherapist asks a patient to use equipment with an estimated weight. However, the effectiveness of a generalized therapy in this way does not always give the expected results. This is related to the fact that these therapies are standardized and do not consider some factors such as the remaining muscle fibres that are not directly affected by the sprain, which does not mean that they should not be considered. Therefore, in the present work, a biomodel of a human knee has been developed and used to evaluate numerically how the ACL acts under an external load, when there are different degrees of injuries, caused by trauma. Four case studies were considered: Case 1 (control case) where the ACL is healthy, Case 2 where the ACL presents a 1^st-degree sprain, Case 3 where the ACL presents a 2^nd-degree sprain, and finally Case 4 where the ACL presents a 3^rd-sprain grade. After performing the analyses, in the control case, it was found that it presents a balance between tensile and compressive stresses. While in the 4th case, the most critical tensile stress decreases while compression stresses increase. This shows that the ligament, having considerable damage, no longer works as it should and can eventually damage the collateral structures. It was found that, when there was a sprain, where the continuity of the ligament is compromised, a second torsional moment occurs in the ACL which causes the tissue fibres not to act according to their normal physiology or in a healthy state. The results obtained from the present study provide the possibility of predicting where the following injuries will occur by considering the von Mises failure criterion. Likewise, they will allow to improve the therapeutic procedures considering not only the injured structure but also the system as a whole.

[Tendinopathies of the Achilles tendon]

Disorders of the Achilles tendon are among the most frequent musculoskeletal injuries in athletes as well as in the general population. It is very important to differentiate the different clinical pictures summarized under the general term achillodynia and to understand the pathogenesis in order to undertake the correct therapeutic measures. In the case of insertional tendinopathies in particular, a rheumatological origin should be clarified. Doppler ultrasound is the most important diagnostic tool. Evidence-based treatment methods include various training programs, shock wave treatment, diverse injection and surgical procedures, each of which are discussed in detail in this article.

Sex Differences in the Temporalis Tendon-Aponeurotic Complex: An in vivo MRI Macroscopic Analysis in Children and Adolescents

The tendon-aponeurosis complex (TAC) of the temporalis dissipates forces produced during function. Abnormally reduced temporalis TACs have been found in individuals with chronic muscular temporomandibular disorders - a painful musculoskeletal condition that is more frequent in women than men. Whether there are sex differences in the temporalis TAC in healthy individuals is currently unknown. Here, we characterized and measured the temporalis TAC in healthy male and female young individuals between 5 and 15 years old to determine whether the volume of the temporalis TAC and the TAC-to-muscle ratio are different between males and females. We collected MRI studies from 90 healthy individuals, including equal numbers (15 M and 15 F) of young children (ages 5-7), children (9-11), and adolescents (13-15) and segmented the right temporalis and its TAC using software. Using general linear models, we tested the effect of sex, age, and their interaction on the volumes of the temporalis and its TAC, and the TAC-to-muscle ratio. The volumes of the temporalis and its TAC increased with age (both p < 0.001) and were not affected by sex (p = 0.252 and p = 0.179) or by the interaction sex-by-age (p = 0.079 and p = 0.095, respectively). The TAC-to-muscle ratio did not change significantly with age (p = 0.655) and was not affected by sex (0.438) or by the interaction sex-by-age (0.524). We provide, for the first time, volumetric data of the temporalis TAC in children and adolescents. The volumes of the temporalis TAC and the TAC-to-muscle ratio are not different between male and female individuals until the age of 15.

Association of TNF-α -308G > A polymorphism with susceptibility to tendinopathy in athletes: a case-control study

BACKGROUND

High levels of the tumor necrosis factor alpha (TNF-α) induce apoptosis and pro-inflammatory effects for primary degeneration of tendon and development of tendinopathy. The aim of this study was to investigate the association between the TNF-α polymorphisms and tendinopathy in athletes.

METHODS

Two hundred and seventy athletes (135 tendinopathy cases and 135 controls) were included and genotyped (TNF-α -1031T > C; -857 C > T; -308G > A) using TaqMan validated assays. The association of the polymorphisms with tendinopathy was evaluated by a multivariate logistic regression model, using odds ratios (OR) and 95 % confidence intervals (CI).

RESULTS

The variant allele - 308 A was significantly associated with patellar (OR: 1.9; 95 % CI: 1.01-3.6) or Achilles tendinopathies (OR: 2.7; 95 % CI: 1.1-6.7). No significant differences were found in allele or genotype distributions of the - 1031T > C and - 857 C > T polymorphisms between cases and controls. TNF-α TCA haplotype was associated with increased tendinopathies risk, either considering all cases (OR: 2.6, 95 % CI: 1.3-5.3), patellar (OR: 3.3, 95 % CI: 1.5-7.3), rotator cuff (OR: 3.1, 95 % CI: 1.4-7.2) or Achilles tendinopathies (OR: 3.8, 95 % CI: 1.1-12.7).

CONCLUSIONS

These results suggest that the TNF-α polymorphisms could influence the susceptibility to developing tendinopathy among athletes. Knowledge of the TNF-α polymorphisms associated to tendinopathy in athletes can further understanding of the inflammatory role in the early stages of the disease and contribute for sports injury surveillance programmes, in which athletes with TNF-α TCA haplotype could be early subjected to cryotherapy after training and competition to avoid tendinopathy development.

Explaining Variability in the Prevalence of Achilles Tendon Abnormalities: A Systematic Review With Meta-analysis of Imaging Studies in Asymptomatic Individuals

OBJECTIVE

To estimate the prevalence of, and factors associated with, Achilles tendon abnormalities observed on imaging in asymptomatic individuals.

DESIGN

Systematic review with stratified meta-analysis and meta-regression.

LITERATURE SEARCH

Embase, Scopus, MEDLINE, CINAHL, SPORTDiscus, and Web of Science were searched from 1980 to August 2020.

STUDY SELECTION CRITERIA

We included studies that reported the prevalence of Achilles tendon abnormalities, observed with any imaging modality, in an asymptomatic population. We excluded studies if participant mean age was younger than 12 years or if participants had current/previous lower-limb tendon injuries/symptoms or other systemic conditions.

DATA SYNTHESIS

Random-effects proportion meta-analysis was used to estimate prevalence. We used meta-regression for continuous variables (mean age and body mass index [BMI], sample size, proportion of female participants) and stratified categorical variables (imaging modality and participation in physical activity) to explain between-study heterogeneity.

RESULTS

We included 91 studies (10 156 limbs, 5841 participants). The prevalence of Achilles tendon abnormalities on imaging ranged from 0% to 80% per participant. Between-study heterogeneity was high (I²>90%, P<.001), precluding data pooling. Between-study heterogeneity was partly explained by participant mean BMI (slope, 2.8% per 1-unit increase in BMI; 95% confidence interval: 0.57%, 5.03%; P = .015) and participation in physical activity per limb, and mean age of 40 years old or older (P = .022) per participant.

CONCLUSION

There was substantial variability in the prevalence of Achilles tendon abnormalities on imaging in asymptomatic individuals. Higher prevalence of abnormalities was associated with older age (40 years old or older), higher BMI, and participation in physical activity. A large proportion of heterogeneity remains unaccounted for, likely due to variations in abnormality definitions and study design. J Orthop Sports Phys Ther 2021;51(5):232-252. Epub 28 Mar 2021. doi:10.2519/jospt.2021.9970.

Mitochondrial Transplantation Modulates Inflammation and Apoptosis, Alleviating Tendinopathy Both In Vivo and In Vitro

Tendinopathy is a common musculoskeletal condition causing pain and dysfunction. Conventional treatment and surgical procedures for tendinopathy are insufficient; accordingly, recent research has focused on tendon-healing regenerative approaches. Tendon injuries usually occur in the hypoxic critical zone, characterized by increased oxidative stress and mitochondrial dysfunction; thus, exogenous intact mitochondria may be therapeutic. We aimed to assess whether mitochondrial transplantation could induce anti-inflammatory activity and modulate the metabolic state of a tendinopathy model. Exogenous mitochondria were successfully delivered into damaged tenocytes by centrifugation. Levels of Tenomodulin and Collagen I in damaged tenocytes were restored with reductions in nuclear factor-κB and matrix metalloproteinase 1. The dysregulation of oxidative stress and mitochondrial membrane potential was attenuated by mitochondrial transplantation. Activated mitochondrial fission markers, such as fission 1 and dynamin-related protein 1, were dose-dependently downregulated. Apoptosis signaling pathway proteins were restored to the pre-damage levels. Similar changes were observed in a collagenase injection-induced rat model of tendinopathy. Exogenous mitochondria incorporated into the Achilles tendon reduced inflammatory and fission marker levels. Notably, collagen production was restored. Our results demonstrate the therapeutic effects of direct mitochondrial transplantation in tendinopathy. These effects may be explained by alterations in anti-inflammatory and apoptotic processes via changes in mitochondrial dynamics.

The utilization and effects of filiform dry needling in the management of tendinopathy: a systematic review

Background: Tendinopathy is frequently associated with pain, soft tissue impairments and muscle performance limitations. Dry needling (DN) incorporates a fine filiform needle to penetrate the skin and underlying soft tissue in an effort to decrease pain and improve function. While injectable interventions and gauged-needle tendon fenestration for tendinopathy has been reviewed, DN for tendinopathy has yet to be synthesized.Objective: To systematically review the utilization and effects of DN for tendinopathy.Methods: Six electronic databases (PubMed, CINAHL, Scopus, SportDiscus, PEDro and the Cochrane Library) were searched from inception through August 15, 2020, using appropriate keywords and relevant synonyms.Results: After screening 462 articles, 10 studies met inclusion criteria. Study designs included case reports, case series, and randomized clinical trials. DN was used in isolation in 3/10 studies and as part of a multimodal approach in 7/10 studies. DN was associated with improved pain, function, muscle performance and perceived improvement in each study evaluating the relevant outcome. Conflicting results were found in comparative studies evaluating DN.Conclusions: DN may be a useful adjunctive treatment in the conservative management of tendinopathy, although its discrete effect is unclear. Very Low-quality evidence and methodological limitations suggest further investigation is warranted.

Mitochondrial dysfunction and potential mitochondrial protectant treatments in tendinopathy

Tendinopathy is a common musculoskeletal condition that affects a wide range of patients, including athletes, laborers, and older patients. Tendinopathy is often characterized by pain, swelling, and impaired performance and function. The etiology of tendinopathy is multifactorial, including both intrinsic and extrinsic mechanisms. Various treatment strategies have been described, but outcomes are often variable, as tendons have poor intrinsic healing potential compared with other tissues. Therefore, several novel targets for tendon regeneration have been identified and are being explored. Mitochondria are organelles that generate adenosine triphosphate, and they are considered to be the power generators of the cell. Recently, mitochondrial dysfunction verified by increased reactive oxygen species (ROS), decreased superoxide dismutase activity, cristae disorganization, and decreased number of mitochondria has been identified as a mechanism that may contribute to tendinopathy. This has provided new insights for studying tendinopathy pathogenesis and potential treatments via antioxidant, metabolic modulation, or ROS inhibition. In this review, we present the current understanding of mitochondrial dysfunction in tendinopathy. The review summarizes the potential mechanism by which mitochondrial dysfunction contributes to the development of tendinopathy, as well as the potential therapeutic benefits of mitochondrial protectants in the treatment of tendinopathy.

Industrial Development of Standardized Fetal Progenitor Cell Therapy for Tendon Regenerative Medicine: Preliminary Safety in Xenogeneic Transplantation

Tendon defects require multimodal therapeutic management over extensive periods and incur high collateral burden with frequent functional losses. Specific cell therapies have recently been developed in parallel to surgical techniques for managing acute and degenerative tendon tissue affections, to optimally stimulate resurgence of structure and function. Cultured primary human fetal progenitor tenocytes (hFPT) have been preliminarily considered for allogeneic homologous cell therapies, and have been characterized as stable, consistent, and sustainable cell sources in vitro. Herein, optimized therapeutic cell sourcing from a single organ donation, industrial transposition of multi-tiered progenitor cell banking, and preliminary preclinical safety of an established hFPT cell source (i.e., FE002-Ten cell type) were investigated. Results underlined high robustness of FE002-Ten hFPTs and suitability for sustainable manufacturing upscaling within optimized biobanking workflows. Absence of toxicity or tumorigenicity of hFPTs was demonstrated in ovo and in vitro, respectively. Furthermore, a 6-week pilot good laboratory practice (GLP) safety study using a rabbit patellar tendon partial-thickness defect model preliminarily confirmed preclinical safety of hFPT-based standardized transplants, wherein no immune reactions, product rejection, or tumour formation were observed. Such results strengthen the rationale of the multimodal Swiss fetal progenitor cell transplantation program and prompt further investigation around such cell sources in preclinical and clinical settings for musculoskeletal regenerative medicine.

Platelet-Rich Plasma Versus Corticosteroids in the Treatment of Chronic Plantar Fasciitis: A Systematic Review and Meta-analysis of Prospective Comparative Studies

Plantar fasciitis is a common cause of heel pain, which often results in a significant limitation of daily activity. The objective of this review was to compare platelet-rich plasma injection (PRP) and corticosteroids injection in the treatment of chronic plantar fasciitis. MEDLINE, PubMed, Web of Science, EMBASE, and the Cochrane library of clinical trials were searched in March 2019. Inclusion criteria were prospective comparative studies reporting functional scores or pain score with a minimum follow-up of 1 month. We excluded studies with patients younger than 18 years and patients with a history of surgical intervention, infection, or rheumatological disease. First author, publication year, sample size, type of intervention, outcome measures, and follow-up period were recorded. The American Orthopaedic Foot & Ankle Society score was significantly better in the PRP group at 6 months' follow-up, with a lower visual analogue scale at 6- and 12-month intervals. The Foot and Ankle Disability Index and Roles-Maudsley score were similar in the 2 treatments at 3 and 6 months. PRP injection in the treatment of chronic plantar fasciitis is considered safe, with a favorable functional outcome and pain control at intermediate and long-term follow-up in comparison to corticosteroid injection.

Platelet-Rich Plasma Versus Corticosteroids for the Treatment of Plantar Fasciitis: A Systematic Review and Meta-analysis

BACKGROUND

Plantar fasciitis is a common cause of heel pain. Corticosteroid injections are commonly used and proven to be effective, and lately platelet-rich plasma (PRP) has been used with mixed results.

PURPOSE

To perform a systematic review and meta-analysis comparing intralesional injections of PRP and steroid infiltration.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

A systematic review of Medline, Embase, Scopus, and Google Scholar including all level 1 and 2 studies from 2010 to 2019 was perfomed. American Orthopaedic Foot and Ankle Society and visual analog scale for pain scores were used as outcome variables. Publication bias and risk of bias was assessed with the Cochrane Collaboration tools. The Grading of Recommendations, Assessment, Development and Evaluations system was used to assess the quality of the body of evidence. Heterogeneity was assessed with χ² and I² statistics.

RESULTS

Fifteen studies were included in the analysis. Nine studies had a high risk of bias. There was 1 study with high quality, 9 with moderate, 2 studies with low, and 3 with very low quality. The pooled estimate for the American Orthopaedic Foot and Ankle Society score demonstrated nonsignificant differences at 1 month (P = .4) and 3 months (P = .076). At 6 months (P = .009) and 12 months (P = .009), it indicated significant differences in favor of PRP. The pooled estimate for visual analog scale demonstrated nonsignificant differences at 1 month (P = .653). At 3 months (P = .0001), 6 months (P = .002), and 12 months (P = .019), it yielded significant differences in favor of PRP.

CONCLUSION

The results of this systematic review and meta-analysis suggest that PRP is superior to corticosteroid injections for pain control at 3 months and lasts up to 1 year. In the short term, there is no advantage of corticosteroid infiltration. However, the low study quality, high risk of bias, and different protocols for PRP preparation reduce the internal and external validity of these findings, and these results must be viewed with caution.

Novel self-amplificatory loop between T cells and tenocytes as a driver of chronicity in tendon disease

OBJECTIVES

Increasing evidence suggests that inflammatory mechanisms play a key role in chronic tendon disease. After observing T cell signatures in human tendinopathy, we explored the interaction between T cells and tendon stromal cells or tenocytes to define their functional contribution to tissue remodelling and inflammation amplification and hence disease perpetuation.

METHODS

T cells were quantified and characterised in healthy and tendinopathic tissues by flow cytometry (FACS), imaging mass cytometry (IMC) and single cell RNA-seq. Tenocyte activation induced by conditioned media from primary damaged tendon or interleukin-1β was evaluated by qPCR. The role of tenocytes in regulating T cell migration was interrogated in a standard transwell membrane system. T cell activation (cell surface markers by FACS and cytokine release by ELISA) and changes in gene expression in tenocytes (qPCR) were assessed in cocultures of T cells and explanted tenocytes.

RESULTS

Significant quantitative differences were observed in healthy compared with tendinopathic tissues. IMC showed T cells in close proximity to tenocytes, suggesting tenocyte-T cell interactions. On activation, tenocytes upregulated inflammatory cytokines, chemokines and adhesion molecules implicated in T cell recruitment and activation. Conditioned media from activated tenocytes induced T cell migration and coculture of tenocytes with T cells resulted in reciprocal activation of T cells. In turn, these activated T cells upregulated production of inflammatory mediators in tenocytes, while increasing the pathogenic collagen 3/collagen 1 ratio.

CONCLUSIONS

Interaction between T cells and tenocytes induces the expression of inflammatory cytokines/chemokines in tenocytes, alters collagen composition favouring collagen 3 and self-amplifies T cell activation via an auto-regulatory feedback loop. Selectively targeting this adaptive/stromal interface may provide novel translational strategies in the management of human tendon disorders.

Bringing tendon biology to heel: Leveraging mechanisms of tendon development, healing, and regeneration to advance therapeutic strategies

Tendons are specialized matrix-rich connective tissues that transmit forces from muscle to bone and are essential for movement. As tissues that frequently transfer large mechanical loads, tendons are commonly injured in patients of all ages. Following injury, mammalian tendons heal poorly through a slow process that forms disorganized fibrotic scar tissue with inferior biomechanical function. Current treatments are limited and patients can be left with a weaker tendon that is likely to rerupture and an increased chance of developing degenerative conditions. More effective, alternative treatments are needed. However, our current understanding of tendon biology remains limited. Here, we emphasize why expanding our knowledge of tendon development, healing, and regeneration is imperative for advancing tendon regenerative medicine. We provide a comprehensive review of the current mechanisms governing tendon development and healing and further highlight recent work in regenerative tendon models including the neonatal mouse and zebrafish. Importantly, we discuss how present and future discoveries can be applied to both augment current treatments and design novel strategies to treat tendon injuries.

Three-Dimensional Mapping of Shear Wave Velocity in Human Tendon: A Proof of Concept Study

Ultrasound-based shear wave elastography (SWE) provides the means to quantify tissue mechanical properties in vivo and has proven valuable in detecting degenerative processes in tendons. Its current mode of use is for two-dimensional rendering measurements, which are highly position-dependent. We therefore propose an approach to create a volumetric reconstruction of the mechano-acoustic properties of a structure of interest based on optically tracking the ultrasound probe during free-hand measurement sweeps. In the current work, we aimed (1) to assess the technical feasibility of the three-dimensional mapping of unidirectional shear wave velocity (SWV), (2) to evaluate the possible artefacts associated with hand-held image acquisition, (3) to investigate the reproducibility of the proposed technique, and (4) to study the potential of this method in detecting local adaptations in a longitudinal study setting. Operative and technical feasibility as well as potential artefacts associated with hand-held image acquisition were studied on a synthetic phantom containing discrete targets of known mechanical properties. Measurement reproducibility was assessed based on inter-day and inter-reader scans of the patellar, Achilles, and supraspinatus tendon of ten healthy volunteers and was compared to traditional two-dimensional image acquisition. The potential of this method in detecting local adaptations was studied by testing the effect of short-term voluntary isometric loading history on SWV along the tendon long axis. The suggested approach was technically feasible and reproducible, with a moderate to very good reliability and a standard error of measurement in the range of 0.300-0.591 m/s for the three assessed tendons at the two test-retest modalities. We found a consistent variation in SWV along the longitudinal axis of each tendon, and isometric loading resulted in regional increases in SWV in the patellar and Achilles tendons. The proposed method outperforms traditional two-dimensional measurement with regards to reproducibility and may prove valuable in the objective assessment of pathological tendon changes.

Evaluation of Secretome Tenogenic Potential from Adipose Stem Cells (ACS) in Hypoxic Condition with Fresh Frozen Tendon Scaffold Using Scleraxis (Scx), Insulin-Like Growth Factor 1 (IGF-1) and Collagen Type 1

Various studies have been conducted to see the scaffold that supports the regeneration of tendon. This study aims to analyze thein vitrosecretome tenogenic potential produced by ASCs culture with fresh frozen tendon scaffold in hypoxic conditions. ELISA tests for Scx and IGF-1 levels in secretome were obtained from ASC culture with fresh frozen tendon scaffold under normoxic (21%) and hypoxia (2%) conditions. The immunohistochemical examination of COL-1 was also carried out on the 2ndand 6thdays of cell culture. The secretion of Scx and IGF-1 was increased in secretome from ASC cultures using a fresh frozen tendon scaffold compared with those which did not (p <0.05). In the normoxia condition, Scx and IGF-1 in secretome with fresh frozen tendons had better results than hypoxic conditions (p <0.05). The highest Scx levels were obtained in culture on the 6thday (p <0.05), while the highest IGF-1 levels were obtained in the culture on the 2ndday (p <0.05). There was an increase in the secretion of Scx and IGF-1 from ASC cultures with fresh frozen tendon scaffold under the hypoxic condition of 2%.

Current Advances on the Regeneration of Musculoskeletal Interfaces

The regeneration of the musculoskeletal system has been widely investigated. There is now detailed knowledge about the organs composing this system. Research has also investigated the zones between individual tissues where physical, mechanical, and biochemical properties transition. However, the understanding of the regeneration of musculoskeletal interfaces is still lacking behind. Numerous disorders and injuries can degrade or damage tissue interfaces. Their inability to regenerate can delay the tissue repair and regeneration process, leading to graft instability, high morbidity, and pain. Moreover, the knowledge of the mechanism of tissue interface development is not complete. This review presents an overview of the most recent approaches of the regeneration of musculoskeletal interfaces, including the latest in vitro, preclinical, and clinical studies. Impact statement Interfaces between soft and hard tissues are ubiquitous within the body. These transition zones are crucial for joint motion, stabilisation and load transfer between tissues, but do not seem to regenerate well after injury or deterioration. The knowledge about their biology is vast, but little is known about their development. Various musculoskeletal disorders in combination with risk factors including aging and unhealthy lifestyle, can lead to local imbalances, misalignments, inflammation, pain and restricted mobility. Our manuscript reviews the current approaches taken to promote the regeneration of musculoskeletal interfaces through in vitro, pre-clinical and clinical studies.

Exosomes derived from tendon stem cells promote cell proliferation and migration through the TGF β signal pathway

Tendon stem cells (TSCs) are a kind of progenitor cells found in tendon niches, which play a key role in the repair of tendon injuries. Exosomes that mediate cell communication are involved in physiological processes and various diseases, while the effect of exosomes derived from TSCs (TSC-exo) on TSCs is still unclear. The purpose of this study is to explore the effect of TSC-exo on TSCs. Analyzing the characteristics of TSC-exo, we found that the TSC-exo were enriched in a large amount of transforming growth factor β (TGF β) by western blotting. We also found that the TGF β carried by TSC-exo can effectively accelerate the proliferation and migration of TSCs. We further found that TGF β carried by TSC-exo can activate the TGF β-Smad2/3 and the ERK1/2 signaling pathway in TSCs. Furthermore, matrix metalloenzyme 2 (MMP2), a downstream molecule of Smad2, is regulated by TGF β carried by TSC-exo. Collectively, our findings provide molecular insights into TSC-exo and indicate that TSC-exo are a potential strategy for treating tendon injuries.

Biomechanical evaluation in runners with Achilles tendinopathy

OBJECTIVES

To evaluate the clinical characteristics, ground reaction force (GRF), and function of the plantar muscles and dorsiflexors of the ankle in runners with and without Achilles tendinopathy (AT) and in non-runners.

METHODS

Seventy-two participants (42 men, 30 women; mean age: 37.3±9.9 years) were enrolled in this cross-sectional study and divided into three groups: AT group (ATG, n=24), healthy runners' group (HRG, n=24), and non-runners' group (NRG, n=24). Both ankles were evaluated in each group. The American Orthopedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Scale was used for clinical and functional evaluation. GRF was evaluated using force plates and muscle strength was evaluated using an isokinetic dynamometer.

RESULTS

The AOFAS scores were lower in the ATG. The strike impulse was higher in the ATG than in the HRG and NRG. However, GRF was similar among the groups. The ATG exhibited lower total work at 120°/s speed than the HRG. The peak torque in concentric dorsiflexion was lower in the NRG than in the ATG and HRG. The peak torque and total work in concentric plantar flexion were lower in the NRG than in the ATG. The peak torque and total work in eccentric plantar flexion were lower in the NRG than in the ATG and HRG.

CONCLUSION

Runners with AT showed higher strike impulse, lower muscle strength of the plantar flexors, and higher clinical and functional damage.

2017 Marathon of Rome: Anthropometry and Sport Profile in 350 Runners and Association With Achilles and Patellar Tendinopathy

BACKGROUND

Achilles and patellar tendinopathy are common in runners. Despite the relevance of the problem, causative factors remain poorly understood. This cross-sectional study evaluated the association between Achilles and patellar tendinopathy and age, sex, weight, height, number of marathons, and impact profile in runners who participated in the 2017 Marathon of Rome.

METHODS

At the 2017 Marathon of Rome, 350 athletes (256 men and 94 women; mean age: 44.8 years, range 12-80 years) filled in the VISA-A and VISA-P questionnaires. A fully trained orthopedic surgeon made a diagnosis of Achilles and patellar tendinopathy according to clinical criteria.

RESULTS

Ninety-five participants were diagnosed with Achilles tendinopathy and 96 with patellar tendinopathy. There was evidence of a statistically significant positive association between age and Achilles and patellar tendinopathy, with no effect of sex, weight, and height on the presence of Achilles tendinopathy. There was no evidence of a statistically significant positive association between the number of marathons and impact profile and VISA-A score. There was a statistically significant association between VISA-P score and impact profile. Finally, there was evidence of a statistically significant positive association between VISA-A score and VISA-P score (P = 0.007).

CONCLUSIONS

In marathon runners, there was no evidence of a statistically significant association between sex, weight, height, number of marathons, and Achilles and patellar tendinopathy. However, age was associated with Achilles and patellar tendinopathy, and impact profile was associated with patellar tendinopathy.

Factors associated with outcome following exercise interventions for Achilles tendinopathy: A systematic review

OBJECTIVE

This systematic review aimed to synthesize current evidence on contributing factors influencing outcome following exercise management for Achilles tendinopathy (AT).

DATA SOURCES

Databases (PubMed, Embase, and Cochrane Library) were searched from inception to February 2020.

STUDY SELECTION

Studies investigating factors (e.g., age, BMI) associated with outcome (e.g., pain and function questionnaires) following exercise interventions for AT were included.

DATA EXTRACTION

Data were extracted into a standardized form, including patient demographics, population sample, study type, factors associated with outcome, and outcome measures.

DATA SYNTHESIS

Meta-analysis was planned to be performed, where appropriate. Where data could not be pooled, we summarized the findings descriptively.

RESULTS

Six studies investigating 11 different factors were included; overall the quality of evidence was poor. There was conflicting evidence that imaging measures had an association with a change in VISA-A outcome. These included signal intensity and tendon size determined by MRI, and Ultrasound Tissue Characterization echopattern. Three studies found that duration of symptoms was not associated with a change in VISA-A. Also, three studies found that age, and one study found that prior sporting activity level, were not associated with outcome. Baseline pain with activity, baseline VISA-A, sex, and BMI were inconsistently associated with specific outcomes.

CONCLUSION

Due to the poor quality of evidence overall, no firm conclusions can be drawn. At best, there was inconsistent evidence that imaging factors, baseline pain and function, BMI, and sex showed some associations with outcomes, but these findings need to be confirmed in more extensive studies.

Effects and Mechanism of Berberine on the Dexamethasone-Induced Injury of Human Tendon Cells

Objective

To investigate the effects of berberine (Berb) on dexamethasone- (Dex-) induced injury of human tendon cells and its potential mechanism.

Methods

CCK-8 assay was used to explore the appropriate concentration of Dex-induced injury of tendon cells and the doses of Berb attenuates Dex cytotoxicity; cell wound healing assay was used to detect the effects (P < 0.05) of Berb and Dex on the migration ability of tendon cells; flow cytometry was used to measure cell apoptosis; DCF DA fluorescent probe was used to measure the ROS activity of cells. Western blotting was used to detect the expression of phenotype related factors including smooth muscle actin α (SMA-α), type I collagen (Col I), col III, apoptosis-related factors, caspase-3, cleaved caspase-3, caspase-9, cleaved caspase-9, and PI3K/AKT.

Results

CCK-8 assay showed that 1-100 μM Dex significantly inhibited the proliferation of tendon cells in a concentration-dependent manner (P < 0.05), where the inhibitory effect of 100 μM Dex was most significant (P < 0.005), and the pretreatment of 150, 200 μM Berb could reverse those inhibitions (all P < 0.05). Compared with the control group, Dex significantly inhibited cell migration (P < 0.05), while Berb pretreatment could enhance cell migration (P < 0.05). Flow cytometry and ROS assay showed that Dex could induce apoptosis and oxidative stress response of tendon cells (all P < 0.05), while Berb could reverse those responses (P < 0.05). Western blot showed that Dex could inhibit the expression of the col I and III as well as α-SMA (all P < 0.05) and enhance the expression of apoptosis-related factors including cleaved caspase-3 and cleaved caspase-9 (all P < 0.05). Besides, Dex could also inhibit the activation of the PI3K/AKT signaling pathway (all P < 0.05), thus affecting cell function, while Berb treatment significantly reversed the expression of those above proteins (all P < 0.05).

Conclusion

Berb attenuated DEX induced reduction of proliferation and migration, oxidative stress, and apoptosis of tendon cells by activating the PI3K/AKT signaling pathway and regulated the expression of phenotype related biomarkers in tendon cells. However, further studies are still needed to clarify the protective effects of Berb in vivo.

Role of Mechanical Loading for Platelet-Rich Plasma-Treated Achilles Tendinopathy

There is no consensus on the optimal rehabilitation protocol after platelet-rich plasma (PRP) treatment for tendinopathy despite basic science studies showing the critical role of mechanical loading in the restoration of tendon structure and function posttreatment. In this article, we will review tendon mechanobiology, platelet biology, and review levels I and II Achilles tendon clinical studies paying particular attention to the role of mechanical loading in rehabilitation of injured tendons. Animal studies emphasize the synergistic effect of mechanical tendon loading and PRP to treat tendon injury while clinical studies described minimal details on loading protocols.

Regeneration of a full-thickness defect in rotator cuff tendon with umbilical cord-derived mesenchymal stem cells in a rat model

Although rotator cuff disease is a common cause of shoulder pain, there is still no treatment method that could halt or reveres its development and progression. The purpose of this study was to investigate the efficacy of umbilical cord-derived mesenchymal stem cells (UC MSCs) on the regeneration of a full-thickness rotator cuff defect (FTD) in a rat model. We injected either UC MSCs or saline to the FTD and investigated macroscopic, histological and biomechanical results and cell trafficking. Treatment with UC MSCs improved macroscopic appearance in terms of tendon thickness at two weeks, and inflammation, defect size, swelling/redness and connection surrounding tissue and slidability at four weeks compared to the saline group. Histologically, UC MSCs induced the tendon matrix formation recovering collagen organization, nuclear aspect ratio and orientation angle of fibroblast as well as suppressing cartilage-related glycosaminoglycan compared to saline group at four weeks. The UC MSCs group also improved ultimate failure load by 25.0% and 19.0% and ultimate stress by 27.3% and 26.8% at two and four weeks compared to saline group. UC MSCs labeled with PKH26 exhibited 5.3% survival at four weeks compared to three hours after injection. This study demonstrated that UC MSCs regenerated the FTD with tendon tissue similar properties to the normal tendon in terms of macroscopic, histological and biomechanical characteristics in a rat model.

A brief history of tendon and ligament bioreactors: Impact and future prospects

Bioreactors are powerful tools with the potential to model tissue development and disease in vitro. For nearly four decades, bioreactors have been used to create tendon and ligament tissue-engineered constructs in order to define basic mechanisms of cell function, extracellular matrix deposition, tissue organization, injury, and tissue remodeling. This review provides a historical perspective of tendon and ligament bioreactors and their contributions to this advancing field. First, we demonstrate the need for bioreactors to improve understanding of tendon and ligament function and dysfunction. Next, we detail the history and evolution of bioreactor development and design from simple stretching of explants to fabrication and stimulation of two- and three-dimensional constructs. Then, we demonstrate how research using tendon and ligament bioreactors has led to pivotal basic science and tissue-engineering discoveries. Finally, we provide guidance for new basic, applied, and clinical research utilizing these valuable systems, recognizing that fundamental knowledge of cell-cell and cell-matrix interactions combined with appropriate mechanical and chemical stimulation of constructs could ultimately lead to functional tendon and ligament repairs in the coming decades.

Polysaccharide Extracted from Bletilla striata Promotes Proliferation and Migration of Human Tenocytes

Tendon healing after injury is relatively slow, mainly because of the weak activity and metabolic properties of tendon cells (tenocytes). Bletilla striata polysaccharide (BSP) has been reported to enhance cell proliferation. Here, we aimed to increase tendon cell proliferation by BSP treatment. We isolated tenocytes from the flexor tendon of human origin. Moreover, we improved the process of extracting BSP. When human tenocytes (HTs) were treated with 100 μg/mL BSP, the MEK/ERK1/2 and PI3K/Akt signaling pathways were activated, thereby enhancing the proliferation ability of tenocytes. BSP treatment also increased the migration of HTs and their ability to secrete the extracellular matrix (Col-I and Col-III). In conclusion, BSP was successfully extracted from a natural Chinese herbal extract and was shown to enhance tenocytes proliferation, migration and collagen release ability. This study is the first to demonstrate improved healing of tendons using BSP.

Holistic Approach of Swiss Fetal Progenitor Cell Banking: Optimizing Safe and Sustainable Substrates for Regenerative Medicine and Biotechnology

Safety, quality, and regulatory-driven iterative optimization of therapeutic cell source selection has constituted the core developmental bedrock for primary fetal progenitor cell (FPC) therapy in Switzerland throughout three decades. Customized Fetal Transplantation Programs were pragmatically devised as straightforward workflows for tissue procurement, traceability maximization, safety, consistency, and robustness of cultured progeny cellular materials. Whole-cell bioprocessing standardization has provided plethoric insights into the adequate conjugation of modern biotechnological advances with current restraining legislative, ethical, and regulatory frameworks. Pioneer translational advances in cutaneous and musculoskeletal regenerative medicine continuously demonstrate the therapeutic potential of FPCs. Extensive technical and clinical hindsight was gathered by managing pediatric burns and geriatric ulcers in Switzerland. Concomitant industrial transposition of dermal FPC banking, following good manufacturing practices, demonstrated the extensive potential of their therapeutic value. Furthermore, in extenso, exponential revalorization of Swiss FPC technology may be achieved via the renewal of integrative model frameworks. Consideration of both longitudinal and transversal aspects of simultaneous fetal tissue differential processing allows for a better understanding of the quasi-infinite expansion potential within multi-tiered primary FPC banking. Multiple fetal tissues (e.g., skin, cartilage, tendon, muscle, bone, lung) may be simultaneously harvested and processed for adherent cell cultures, establishing a unique model for sustainable therapeutic cellular material supply chains. Here, we integrated fundamental, preclinical, clinical, and industrial developments embodying the scientific advances supported by Swiss FPC banking and we focused on advances made to date for FPCs that may be derived from a single organ donation. A renewed model of single organ donation bioprocessing is proposed, achieving sustained standards and potential production of billions of affordable and efficient therapeutic doses. Thereby, the aim is to validate the core therapeutic value proposition, to increase awareness and use of standardized protocols for translational regenerative medicine, potentially impacting millions of patients suffering from cutaneous and musculoskeletal diseases. Alternative applications of FPC banking include biopharmaceutical therapeutic product manufacturing, thereby indirectly and synergistically enhancing the power of modern therapeutic armamentariums. It is hypothesized that a single qualifying fetal organ donation is sufficient to sustain decades of scientific, medical, and industrial developments, as technological optimization and standardization enable high efficiency.

Hypoxia-Induced Mesenchymal Stem Cells Exhibit Stronger Tenogenic Differentiation Capacities and Promote Patellar Tendon Repair in Rabbits

Tendon injury is a common but tough medical problem. Unsatisfactory clinical results have been reported in tendon repair using mesenchymal stem cell (MSC) therapy, creating a need for a better strategy to induce MSCs to tenogenic differentiation. This study was designed to examine the effect of hypoxia on the tenogenic differentiation of different MSCs and their tenogenic differentiation capacities under hypoxia condition in vitro and to investigate the in vivo inductility of hypoxia in tenogenesis. Adipose tissue-derived MSCs (AMSCs) and bone marrow-derived MSCs (BMSCs) were isolated and characterized. The expression of hypoxia-induced factor-1 alpha (Hif-1α) was examined to confirm the establishment of hypoxia condition. qRT-PCR, western blot, and immunofluorescence staining were used to evaluate the expression of tendon-associated marker Col-1a1, Col-3a1, Dcn, and Tnmd in AMSCs and BMSCs under hypoxia condition, compared with Tgf-β1 induction. In vivo, a patellar tendon injury model was established. Normoxic and hypoxic BMSCs were cultured and implanted. Histological, biomechanical, and transmission electron microscopy analyses were performed to assess the improved healing effect of hypoxic BMSCs on tendon injury. Our in vitro results showed that hypoxia remarkably increased the expression of Hif-1α and that hypoxia not only promoted a significant increase in tenogenic markers in both AMSCs and BMSCs compared with the normoxia group but also showed higher inductility compared with Tgf-β1. In addition, hypoxic BMSCs exhibited higher potential of tenogenic differentiation than hypoxic AMSCs. Our in vivo results demonstrated that hypoxic BMSCs possessed better histological and biomechanical properties than normoxic BMSCs, as evidenced by histological scores, patellar tendon biomechanical parameters, and the range and average of collagen fibril diameters. These findings suggested that hypoxia may be a practical and reliable strategy to induce tenogenic differentiation of BMSCs for tendon repair and could enhance the effectiveness of MSCs therapy in treating tendon injury.

Management of Achilles and patellar tendinopathy: what we know, what we can do

Tendinopathies are challenging conditions frequent in athletes and in middle-aged overweight patients with no history of increased physical activity. The term “tendinopathy” refers to a clinical condition characterised by pain, swelling, and functional limitations of tendons and nearby structures, the effect of chronic failure of healing response. Tendinopathies give rise to significant morbidity, and, at present, only limited scientifically proven management modalities exist. Achilles and patellar tendons are among the most vulnerable tendons, and among the most frequent lower extremity overuse injuries. Achilles and patellar tendinopathies can be managed primarily conservatively, obtaining good results and clinical outcomes, but, when this approach fails, surgery should be considered. Several surgical procedures have been described for both conditions, and, if performed well, they lead to a relatively high rate of success with few complications. The purpose of this narrative review is to critically examine the recent available scientific literature to provide evidence-based opinions on these two common and troublesome conditions.

The Effectiveness of Minimally Invasive Techniques in the Treatment of Patellar Tendinopathy: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

The aim was to determine the effectiveness of minimally invasive techniques (MIT) in patients with patellar tendinopathy. Database searches were performed for randomized controlled trials (RCTs) in electronic databases (WOS, Cochrane Central, SportDiscus, and Medline via PubMed and PEDro). The inclusion criteria used were published in English or Spanish and involving adults with patellar tendinopathy (pain on the inferior pole of the patella for a minimum of 3 months), with at least one group receiving MIT. The quality of the relevant RCTs was evaluated using the PEDro scale. The primary outcome was functionality using the VISA-p questionnaire. Secondary outcome was focused on pain. A total of 1164 studies were screened for possible inclusion in our systematic review. Finally, 10 RCTs were included with a total of 326 individuals. Five RCTs were included in the meta-analysis. The quality assessment revealed that all the studies included were considered to possess high methodological quality. All studies analyzing MIT such as platelet-rich plasma (PRP), dry needling, or skin-derived tenocyte-like cells, when combined with exercise, proved to be effective for patellar tendinopathy. Moreover, the PRP technique with doses greater than 4 mL together and combined with an exercise program lasting over 6 weeks obtained better results in functionality and pain than other treatments in the short term. However, in the long term, dry needling and skin-derived tenocyte-like cells are more effective than PRP. Although the infiltration of drugs was effective at posttreatment, these improvements were not maintained over time and may have secondary effects. Although there are no RCTs analyzing the effectiveness of MIT like percutaneous needle electrolysis, there has been an increasing number of publications achieving excellent results in the last years. However, it is necessary to develop RCTs analyzing not only the effect but also comparing the effectiveness between different MIT such as dry needling and percutaneous needle electrolysis.

Physical therapy for tendinopathy: An umbrella review of systematic reviews and meta-analyses

OBJECTIVE

To summarize evidence in the last decade regarding the efficacy of physical therapy interventions to treat tendinopathy, as a single disease entity, as determined in systematic reviews (SRs) and/or meta-analyses (MAs).

METHODS

Electronic search of PubMed, PEDro, and Scopus database was performed from year 2010 to January 2020. The methodological quality of the identified studies was assessed using the AMSTAR 2 tool. Studies scoring 9 points or higher were further analyzed using GRADE principles.

RESULTS

40 SRs and/or MAs were included in qualitative synthesis, whereas only 5 MAs were included in quantitative synthesis. Low-level laser therapy (LLLT) intervention showed a pooled improvement in pain reduction of 1.53 cm; 95% CI, [1.14, 1.91] (I² = 1.9%, p = 0.361) on visual analogue scale, and grip strength of 9.59 kg; 95% CI, [5.90, 13.27].

CONCLUSIONS

Moderate-quality evidence may support these following interventions: LLLT revealed a statistically and potentially clinically significant improvement in pain and function on the short-term. Extracorporeal shockwave therapy showed a statistically significant enhancement in pain and function at all follow-up durations; however, its clinical significance was undetermined. Eccentric exercise was supported by qualitative evidence only. Caution is advised when interpreting results due to possible pathological differences in tendinopathy at each region.

Does moxonidine reduce Achilles tendon or musculoskeletal pain in women with polycystic ovarian syndrome? A secondary analysis of a randomised controlled trial

BACKGROUND

Sympathetic activity and insulin resistance have recently been linked with chronic tendon and musculoskeletal pain. Polycystic ovarian syndrome is linked with insulin resistance and increased sympathetic drive and was therefore an appropriate condition to study the effects of modulating sympathetic activity on Achilles tendon and musculoskeletal symptoms.

METHODS

A secondary analysis of a double-blinded, randomised controlled trial on women with polycystic ovarian syndrome was conducted. Participants received 12 weeks of moxonidine (n = 14) or placebo (n = 18). Musculoskeletal symptom and Victorian Institute of Sport Assessment - Achilles (VISA-A) questionnaires were distributed, and ultrasound tissue characterisation quantified tendon structure at 0 and 12 weeks. 2-way ANOVA was used for multiple comparisons.

RESULTS

There was no difference in mean change in musculoskeletal symptoms (- 0.6 ± 1.7 vs - 0.4 ± 1.8, p = 0.69) or VISA-A (moxonidine - 0.2 ± 8.8 vs placebo + 4.2 ± 14.6, p = 0.24) attributable to the intervention. There was no difference in any measures of Achilles structure. Moxonidine did not reduce sympathetic drive when compared to placebo.

CONCLUSIONS

This was the first study to investigate the effects of blocking sympathetic drive on musculoskeletal and Achilles tendon symptoms in a metabolically diverse population. While the study was limited by small sample size and lack of sympathetic modulation, moxonidine did not change tendon pain/structure or musculoskeletal symptoms.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01504321 . Registered 5 January 2012.

A Perspective on Reversibility of Tendinosis-Induced Multi-Level Adaptations

Achilles tendinopathy is a well-known pathology that can display interindividual variations in chronicity, symptom presentation, and tendon morphology. Furthermore, symptoms may fluctuate within an individual throughout the stages of the pathology. Although pain is often used as a marker of condition severity, individuals may not consistently report pain due to periods of remission. Persons with tendinosis, which is characterized by advanced morphological alterations, have shown consistent changes in neuromechanics that indicate adaptations in the sensory-motor and the central nervous systems. The current treatment strategy involves repetitive resistance exercise aiming to achieve recovery of lost function. This treatment approach, however, has gauged such functional recovery through symptom relief and return to sport, which, in our opinion, may not suffice and may not prevent symptom recurrence or tendon rupture. In this physiologically informed perspective, we briefly review what is currently known about the consequences of Achilles tendon degeneration and examine the topic of reversing these changes. Shortcomings of contemporary treatment strategies are discussed and we therefore call for a new paradigm to focus on the whole-body level, targeting not only the tendon but also the reversal of the neuromotor control system adaptations.

Effect of autologous adipose-derived mesenchymal stem cell therapy in combination with autologous platelet-rich plasma in the treatment of elbow tendinopathy

Tendinopathy is a common condition of both the athletic and general population and can be associated with significant pain and disability. The ability of mesenchymal stem cells (MSCs) to differentiate along a mesodermal cell lineage, including tenocytes, and secrete various bioactive regenerative and anti-inflammatory molecules has seen them considered as a future reparative therapy for tendinopathy. Preclinical trials with MSCs have shown promising positive functional and structural outcomes in several connective tissue related conditions. A 52-year-old male professional masters golfer presents with a clinical history of common extensor origin tendinopathy of the elbow. Subsequent formal ultrasound showed evidence of a large intrasubstance tear. The patient underwent intratendinous autologous adipose-derived MSC therapy in combination with autologous platelet-rich plasma. Following treatment, the patient reported progressive improvement as measured by the validated Numeric Pain Rating Scale and Patient-Rated Tennis Elbow Evaluation score. Repeat imaging showed successful regeneration of tendon-like tissue.

HAPTOGLOBIN POLYMORPHISM AND CHRONIC TENDINOPATHY

Introduction: Tendinopathy is a pathology of tendons of multifactorial origin displayed clinically as chronic degenerative tissue resulting in dysfunction and painful musculoskeletal system. Genetic implications in tendinopathy are not fully elucidated. Haptoglobin (Hp) polymorphism has been investigated for potential role in several diseases such as cardiovascular diseases. This study aims at investigating Hp polymorphism potential association with chronic tendinopathy in Jordan. Materials and Methods: A hospital-based case-control study, of 101 patients diagnosed with chronic tendinopathy and 104 age and gender matched controls, was employed and Hpphenotypes distributions were determined using Sodium Dodecyl Sulphate Polyacrylamide gel electrophoresis technique. Results: showed a significant association between tendinopathy cases and controls in relation to Hpphenotypes frequencies (Fisher’s Exact Test, [Formula: see text]). Odd ratios showed that the odds of tendinopathy cases in Hp2.1 group were reduced while odds in Hp2.2 and Hp1.1 were increased by 3.22 and 7.34 times, respectively, as likely compared to the controls. Conclusion: Results suggested that Hppolymorphism might play a role in chronic tendinopathy genesis.

Electrospun PLGA Fiber Diameter and Alignment of Tendon Biomimetic Fleece Potentiate Tenogenic Differentiation and Immunomodulatory Function of Amniotic Epithelial Stem Cells

Injured tendons are challenging in their regeneration; thus, tissue engineering represents a promising solution. This research tests the hypothesis that the response of amniotic epithelial stem cells (AECs) can be modulated by fiber diameter size of tendon biomimetic fleeces. Particularly, the effect of electrospun poly(lactide-co-glycolide) (PLGA) fleeces with highly aligned microfibers possessing two different diameter sizes (1.27 and 2.5 µm: ha1- and ha2-PLGA, respectively) was tested on the ability of AECs to differentiate towards the tenogenic lineage by analyzing tendon related markers (Collagen type I: COL1 protein and mRNA Scleraxis: SCX, Tenomodulin: TNMD and COL1 gene expressions) and to modulate their immunomodulatory properties by investigating the pro- (IL-6 and IL-12) and anti- (IL-4 and IL-10) inflammatory cytokines. It was observed that fiber alignment and not fiber size influenced cell morphology determining the morphological change of AECs from cuboidal to fusiform tenocyte-like shape. Instead, fleece mechanical properties, cell proliferation, tenogenic differentiation, and immunomodulation were regulated by changing the ha-PLGA microfiber diameter size. Specifically, higher DNA quantity and better penetration within the fleece were found on ha2-PLGA, while ha1-PLGA fleeces with small fiber diameter size had better mechanical features and were more effective on AECs trans-differentiation towards the tenogenic lineage by significantly translating more efficiently SCX into the downstream effector TNMD. Moreover, the fiber diameter of 1.27 µm induced higher expression of pro-regenerative, anti-inflammatory interleukins mRNA expression (IL-4 and IL-10) with favorable IL-12/IL-10 ratio with respect to the fiber diameter of 2.5 µm. The obtained results demonstrate that fiber diameter is a key factor to be considered when designing tendon biomimetic fleece for tissue repair and provide new insights into the importance of controlling matrix parameters in enhancing cell differentiation and immunomodulation either for the cells functionalized within or for the transplanted host tissue.

Bilateral changes in tendon structure of patients diagnosed with unilateral insertional or midportion achilles tendinopathy or patellar tendinopathy

PURPOSE

Changes in tendon structure are commonly seen in patients with unilateral achilles (AT) or patellar (PT) tendinopathy but might also be present on the asymptomatic side, indicating a higher risk for developing symptoms. The aim of this study is to compare tendon structure of the symptomatic side with the asymptomatic side in AT and PT patients and control subjects.

METHODS

A total of 46 patients with unilateral AT (16 insertional and 30 midportion) and 38 with unilateral PT were included. For the control group, a total of 18 Achilles tendons and 25 patellar tendons were scanned. Tendon structure was assessed using ultrasound tissue characterisation (UTC), which quantifies tendon organisation dividing the structure into four different echo types (I-IV).

RESULTS

There were significant differences in echo types I, III, and IV between symptomatic and asymptomatic sides and controls. Additionally, there was a significant difference between the symptomatic and the asymptomatic side for all tendinopathy locations. In the insertional AT tendon portion, the symptomatic side showed a higher percentage of echo type III. For the midportion AT, the symptomatic side showed a lower percentage of echo type I and a higher percentage of echo types III and IV. For the patellar tendon, the symptomatic side showed a higher percentage of echo types III and IV. All differences were higher than the minimal detectable changes.

CONCLUSION

Although patients have symptoms unilaterally, the tendon structures are compromised on both sides. These results stress the importance of monitoring both symptomatic and asymptomatic tendon structures and in addition highlight that the asymptomatic side should not be used as reference in clinical practice.

LEVEL OF EVIDENCE

III.

Efficacy of Stem Cell Therapy for Tendon Disorders: A Systematic Review

Background:

Stem cell therapy is an emerging treatment for tendon disorders.

Purpose:

To systematically review the efficacy of stem cell therapy for patients with tendon disorders.

Study Design:

Systematic review; Level of evidence, 4.

Methods:

MEDLINE/PubMed, EMBASE, CINAHL, CENTRAL, PEDro, and SPORTDiscus; trial registers; and gray literature were searched to identify randomized controlled trials (RCTs) and non-RCTs, cohort studies, and case series with 5 or more cases. Studies investigating any type of stem cell therapy for patients with tendon disorders were eligible if they included patient-reported outcome measures or assessed tendon healing. Risk of bias was assessed through use of the Cochrane risk of bias tools.

Results:

This review included 8 trials (289 patients). All trials had moderate to high risk of bias (level 3 or 4 evidence). In Achilles tendon disorders, 1 trial found that allogenic-derived stem cells led to a faster recovery compared with platelet-rich plasma. Another study found no retears after bone marrow–derived stem cell therapy was used in addition to surgical treatment. There were 4 trials that studied the efficacy of bone marrow–derived stem cell therapy for rotator cuff tears. The controlled trials reported superior patient-reported outcomes and better tendon healing. A further 2 case series found that stem cell therapy improved patient-reported outcomes in patients with patellar tendinopathy and elbow tendinopathy.

Conclusion:

Level 3 evidence is available to support the efficacy of stem cell therapy for tendon disorders. The findings of available studies are at considerable risk of bias, and evidence-based recommendations for the use of stem cell therapy for tendon disorders in clinical practice cannot be made at this time. Stem cell injections should not be used in clinical practice given the lack of knowledge about potentially serious adverse effects.

Common Musculoskeletal Disorders in the Elderly: The Star Triad

Musculoskeletal disorders are debilitating conditions that significantly impair the state of health, especially in elderly subjects. A pathological triad of inter-related disorders that are highly prevalent in the elderly consists of the following main “components”: sarcopenia, tendinopathies, and arthritis. The aim of this review is to critically appraise the literature relative to the different disorders of this triad, in order to highlight the pathophysiological common denominator and propose strategies for personalized clinical management of patients presenting with this combination of musculoskeletal disorders. Their pathophysiological common denominator is represented by progressive loss of (focal or generalized) neuromuscular performance with a risk of adverse outcomes such as pain, mobility disorders, increased risk of falls and fractures, and impaired ability or disability to perform activities of daily living. The precise management of these disorders requires not only the use of available tools and recently proposed operational definitions, but also the development of new tools and approaches for prediction, diagnosis, monitoring, and prognosis of the three disorders and their combination.

Influence of genetic factors in elbow tendon pathology: a case-control study

Elbow tendinopathy is a common pathology of the upper extremity that impacts both athletes and workers. Some research has examined the genetic component as a risk factor for tendinopathy, mainly in the lower limbs. A case-control study was designed to test for a relationship between certain collagen gene single nucleotide polymorphisms (SNPs) and elbow tendon pathology. A sample of 137 young adult athletes whose sports participation involves loading of the upper limb were examined for the presence of structural abnormalities indicative of pathology in the tendons of the lateral and medial elbow using ultrasound imaging and genotyped for the following SNPs: COL5A1 rs12722, COL11A1 rs3753841, COL11A1 rs1676486, and COL11A2 rs1799907. Anthropometric measurements and data on participants’ elbow pain and dysfunction were collected using the Disabilities of the Arm, Shoulder and Hand and the Mayo Clinic Performance Index for the Elbow questionnaires. Results showed that participants in the structural abnormality group had significantly higher scores in pain and dysfunction. A significant relationship between COL11A1 rs3753841 genotype and elbow tendon pathology was found (p = 0.024), with the CT variant associated with increased risk of pathology.