Inflammatory mechanisms linking obesity and tendinopathy

Effect of Prior Bariatric Surgery on the Outcomes of Joint Arthroplasty: A Systematic Review and Meta-Analysis

OBJECTIVE

Obesity is a risk factor for joint arthroplasty complications. With this systematic review and meta-analysis, we assessed whether a positive history of bariatric surgery influences postoperative outcomes in patients undergoing various types of joint arthroplasty.

METHODS

We conducted a comprehensive search database such as Scopus, PubMed, Medline Ovid, CNKI, and CENTRAL for studies comparing outcomes between patients undergoing arthroplasty with and without a history of bariatric surgery. We extracted data on short-term medical complications, venous thromboembolism (VTE), periprosthetic infections, superficial wound infections, hospital stay length, and operative time. We used the data to conduct meta-analyses using random-effects models and subgroup analyses based on the type of arthroplasty.

RESULTS

Overall, 15 studies with nearly 150,000 participants were included. The analysis showed that prior bariatric surgery did not significantly affect overall medical complications post-arthroplasty, with OR of 0.968 (95%CI, 0.706-1.327). For VTE, the results similarly indicated no substantial difference, with an OR of 0.912 (95%CI, 0.644-1.291). In assessing periprosthetic infections, the OR was 0.754 (95%CI, 0.535-1.064), showing comparable rates between patients with and without a history of bariatric surgery.Regarding superficial wound infections, the analysis produced an OR of 2.390 (95%CI, 0.723-7.897), indicating variability but not statistical significance. Hospital stay length was reduced in patients with a history of bariatric surgery, reflected by SMD of -0.113 (95%CI, -0.221 to -0.005). Lastly, operative time also showed a significant reduction, with an SMD of -0.462 (95%CI, -0.865 to -0.059).

CONCLUSIONS

Prior bariatric surgery does not reduce the risk of short-term complications post-arthroplasty, but it seems to reduce the hospital stay length and operative time. The effects vary significantly across different types of joint arthroplasty, suggesting a need for tailored preoperative assessments and care protocols.

PROTOCOL REGISTRATION

This systematic review and meta-analysis was registered at PROSPERO, with the number: CRD42024539052.

Obesity-driven musculotendinous remodeling impairs tissue resilience to mechanical damage

Obesity has been associated with lower muscle strength-to-body mass ratio. Here, we evaluated the effects of diet-induced obesity on the mechano-structural properties of isolated muscles and tendons. Thirty 10-week-old male C57BL/6 J mice were randomly assigned to either an obesogenic high-fat diet group (OB) for 24 weeks or a control group (CN) maintained on a standard chow diet. Soleus muscle (SOL) and Achilles tendon (AT) specimens were isolated and subjected either to failure testing, 300 cycles of passive stretch-destretch, or isometric twitch contractions. Morpho-structural and protein expression analyses were conducted to assess collagen and adipose tissue accumulation, concentrations of cross-linking factors, and any alterations in the POSTN-TGFβ1-Akt signaling pathway. OB SOL and AT tissues were more fragile than those from CN (p < 0.05). A piecewise linear regression model revealed a tendency for OB tissues to exhibit steeper mechanical property changes within the first 20 cycles compared to CN, followed by a similar plateau phase in both groups. OB SOL-AT complexes showed a slower twitch-contraction-relaxation pattern than CN (p < 0.05). OB tendons and muscles were larger than those of the CN, with muscles featuring bigger fibers, and higher collagen area fraction (p < 0.05). Elevated TGFβ1 and POSTN concentrations were observed in OB tissues (p < 0.05), alongside increased P-Akt and P-4EBP1 expression (p < 0.05). These findings highlight the detrimental effects of obesity on the structural integrity of muscle and tendon tissues and suggest a significant role of POSTN-TGFβ1-Akt signaling in obesity-associated musculotendinous remodeling.

Risk factors for atraumatic isolated subscapularis tear: glenoid retroversion

BACKGROUND

Subscapularis tendon (SSC) tears have recently become an area of current research focus. However, the risk factors for atraumatic isolated SSC tears, particularly anatomical factors, remain poorly determined. Therefore, the purpose of this study was to identify the associated factors contributing to isolated SSC tears.

METHODS

This study involved single shoulders of 605 subjects drawn from a cohort of rural residents. The inclusion criteria required each subject to sign an informed consent document and to have a complete clinical evaluation. The exclusion criteria comprised the absence of a complete magnetic resonance imaging study, current medication use that might have affected serum lipid levels, a history of shoulder trauma or surgery, and the presence of osteoarthritis, calcific tendinitis, frozen shoulder, or superior or posterosuperior rotator cuff tear. Diagnoses of isolated SSC tear were based on magnetic resonance imaging findings. Logistic regression analysis was conducted using demographic, physical, social, anatomical, comorbidities, and serological parameters. Anatomical variables included the supraspinatus fossa glenoid angle on axial (SGAX), a method to measure glenoid version, coracohumeral distance on axial and sagittal plans, and coracoid index. When multicollinearity among studied variables was detected, separate multivariable analyses were performed to address this issue, with each analysis including only one of those multicollinear variables along with the other significant variables obtained from univariate analyses.

RESULTS

Among anatomical variables, coracohumeral distance on axial and sagittal planes, as well as the coracoid index, did not show significant associations. However, SGAX, an index of glenoid version, was found to be significantly associated with atraumatic isolated SSC tears. Greater glenoid retroversion is significantly associated with atraumatic isolated SSC tears, along with age, waist circumference, dominant side involvement, manual labor, diabetes, metabolic syndrome, and biceps tendon injury (P ≤ .013).

CONCLUSIONS

The SGAX, serving as an index for glenoid version, is an independently associated factor for atraumatic isolated subscapularis tendon tears, with greater glenoid retroversion being an anatomical risk factor for these tears, along with overuse-related factors such as dominant-side involvement and manual labor, as well as metabolic factors such as obesity, diabetes, metabolic syndrome, and biceps tendon injury.

Myricetin promotes migration and prevents palmitate-induced apoptosis in cultured tenocytes through AMPK-dependent pathways

Myricetin (Myr), a flavonoid present in vegetables and fruits, has been shown to ameliorate inflammation and oxidative stress in various disease models. However, the effects of Myr on hyperlipidemic tenocytes have not been studied. Herein, we aimed to investigate the effects of Myr on the features of tendinopathy in cultured tenocytes under hyperlipidemic conditions. Reactive oxygen species (ROS) were detected by DCFDA. Hydrogen peroxide (H2O2), malondialdehyde (MDA), and caspase 3 activity were quantified via matched assay kits. Apoptotic cells were detected via TUNEL staining. Proteins investigated in this study were evaluated through Western blotting. Treatment with Myr enhanced tenocyte migration and prevented apoptosis, inflammation and oxidative stress in palmitate-treated tenocytes. Myr treatment increased the phosphorylation of AMPK, and the expression of PGC1α and FGF2. siRNA targeting AMPK abrogated the effects of Myr on palmitate-treated tenocytes. However, FGF2 siRNA reduced the impacts of Myr on only cell migration and ECM signaling. These in vitro results suggest that Myr promotes tenocyte migration and ECM signaling via AMPK/FGF2 signaling and attenuates apoptosis through the AMPK-mediated suppression of inflammation and oxidative stress in hyperlipidemic tenocytes. This study sheds light on therapeutic strategies for treating obesity-related tendinopathy.

Modifiable risk factors and inflammation-related proteins in polymyalgia rheumatica: genome-wide meta-analysis and Mendelian randomization

OBJECTIVE

PMR is an age-related inflammatory disease of unknown cause. We aimed to identify potentially modifiable risk factors and therapeutic targets for preventing or treating PMR.

METHODS

We meta-analysed genetic association data from 8156 cases of PMR (defined using diagnostic codes and self-report) and 416 495 controls of European ancestry from the UK Biobank and FinnGen. We then performed Mendelian randomization analyses to estimate the association between eight modifiable risk factors (using data from up to 1.2 million individuals) and 65 inflammation-related circulating proteins (up to 55 792 individuals), using the inverse variance weighted and pleiotropy robust methods.

RESULTS

We identified three novel genome-wide significant loci in the IL1R1, NEK6 and CCDC88B genes and confirmation of previously described associations with HLA-DRB1 and ANKRD55. Genetically predicted smoking intensity (OR 1.32; 95%CI 1.08-1.60; P = 0.006) and visceral adiposity (OR 1.22; 95%CI 1.10-1.37; P = 3.10 × 10-4) were associated with PMR susceptibility. Multiple circulating proteins related to IL-1 family signalling were associated with PMR. IL-1 receptor-like 2, also known as IL-36 receptor (OR 1.25; P = 1.89 × 10-32), serum amyloid A2 (OR 1.06, 9.91 × 10-10) and CXCL6 (OR 1.09, P = 4.85 × 10-7) retained significance after correction for multiple testing.

CONCLUSION

Reducing smoking and visceral adiposity at a population level might reduce incidence of PMR. We identified proteins that may play causal roles in PMR, potentially suggesting new therapeutic opportunities. Further research is needed before these findings are applied to clinical practice.

Panda Rope Bridge Technique promoted Achilles tendon regeneration in a novel rat tendon defect model

PURPOSE

This study aimed to determine whether the Achilles tendon tissue can undergo the pathological process of Achilles tendon regeneration after the Panda Rope Bridge Technique (PRBT).

METHODS

Rats (n = 120) that operated with Achilles tendon rupture were divided into three treatment groups: Defect group (D group), PRBT group and Defect + Fix group (DF group). The D group represented natural healing with no treatment, the PRBT group represented healing receiving PRBT treatment and the DF group represented healing through conservative treatment by ankle fixation. The morphological, histological and biomechanical properties of the defective Achilles tendon were assessed at 7, 10, 12, 14, 28 and 56 days postoperatively.

RESULTS

Compared to that observed in the other two groups, defected rat Achilles tendons that underwent PRBT recruited more cells earlier, eventually forming mature tendons, as revealed by histological analysis. PRBT also enabled defected tendons to regain stronger mechanical properties, thereby improving the prognosis. This improvement may be related to the earlier polarization of macrophages.

CONCLUSION

By establishing and using a novel surgical model of Achilles tendon rupture in rats, most injured Achilles tendons can regenerate and regain normal histological properties, whereas tendons with other interventions formed fibrotic scar tissue. The strong regenerative capacity of tendon tissue enabled us to describe the pathological process of tendon regeneration after PRBT surgery in detail, which would aid in the treatment of tendon injuries. PRBT promotes Achilles tendon regeneration and has the potential to become a standard treatment.

LEVEL OF EVIDENCE

Not applicable.

Lower calf raise efficiency in obesity is partially related to higher triceps surae MTU passive stiffness, hysteresis, and reduced relative strength

The objective of this study was to assess the efficiency of calf raise exercise in individuals with obesity, and to what extent this is related to the structural and mechanical properties of the triceps surae muscle-tendon-unit (MTU). In 22 obese (body mass index; BMI, 32.2 ± 1.5 kg/m2) and 22 nonobese (BMI, 23.3 ± 1.5 kg/m2) men we measured anthropometric parameters, gas exchange, heart rate, and rating of perceived exertion in sitting, standing, and during a self-paced 30-s calf raise exercise. Maximal voluntary isometric contraction of the plantar flexor muscles and passive resistive torque of the triceps surae MTUs were measured using an isokinetic dynamometer. B-mode ultrasound imaging of plantar flexor muscles and Achilles tendon was also performed. Individuals with obesity exhibited a greater metabolic energy cost during standing and calf raise exercise, and a lower exercise efficiency and ankle mobility (P < 0.05). Plantar flexor MTUs stiffness and hysteresis were greater, whereas gastrocnemius-medialis tendon strain was lower in subjects with obesity compared with controls (P < 0.05). There was a negative correlation between calf raise exercise net efficiency, plantar flexor MTUs hysteresis (r = 0.38; P < 0.05), and the body mass by maximal voluntary isometric torque ratio (r = 0.41; P < 0.05). These observations indicate that increased musculotendinous stiffness and hysteresis, together with a lower strength to body mass ratio, are among the factors contributing to higher metabolic energy costs, and lower exercise efficiency in individuals with obesity.NEW & NOTEWORTHY Obesity is associated with greater triceps surae muscle-tendon stiffness, hysteresis, and a lower muscle strength to body mass ratio that, reduce calf raise efficiency, contributing to reduced exercise tolerance in individuals with obesity.

Is Obesity a Risk Factor for Developing Trigger Finger? A Case-Control Analysis of 198 804 Patients

BACKGROUND

Trigger finger (TF) causes pain and functional impairment. Previous studies have associated TF with carpal tunnel syndrome, which has been linked to obesity. This study investigated the relationship between obesity and the prevalence of TF.

METHODS

A retrospective analysis was conducted using data from the TriNetX Research Network (2006-2024). Patients with risk factors for TF (rheumatoid arthritis, gout, amyloidosis, prior carpal tunnel release, spontaneous rupture of flexor tendons, hypothyroidism, Dupuytren disease, and diabetes mellitus) were excluded. Two cohorts were compared: (1) patients diagnosed with TF; and (2) those without. The groups underwent propensity score matching based on demographic attributes using a 1:1 nearest neighbor approach. Each patient's mean body mass index (BMI) was calculated by averaging all BMI measurements. Obesity was defined as a mean BMI greater than or equal to 30 kg/m2. Multiple linear regression and logistic regression, incorporating TF diagnosis, BMI, and matched covariates, were used to adjust for confounding factors and estimate risk and odds ratios.

RESULTS

Data from 198 804 patients (99 402 per group) were analyzed. The prevalence of TF was positively associated with increasing BMI. Multiple linear regression revealed that BMI accounted for a small portion of the variance in TF prevalence. Logistic regression demonstrated an adjusted risk ratio of 1.02 (95% CI = [1.01, 1.03]) and an odds ratio of 1.03 (95% CI = [1.01, 1.05]), indicating a 2% to 3% increased risk of TF in obese patients.

CONCLUSION

Obesity was independently associated with TF. Obese patients had a 2% increased risk of TF compared with nonobese patients.

High-fat diet-induced obesity exacerbated collagenase-induced tendon injury with upregulation of interleukin-1beta and matrix metalloproteinase-1

AIMS

Obesity increases tendinopathy's risk, but its mechanisms remain unclear. This study examined the effect of high-fat diet (HFD)-induced obesity on the outcomes and inflammation of collagenase-induced (CI) tendon injury.

METHODS

Mice were fed with standard chow (SC) or HFD for 12 weeks. Bacterial collagenase I or saline was injected over the patellar tendons of each mouse. At weeks 2 and 8 post-injection, the patellar tendons were harvested for histology, immunohistochemical staining, and gait analysis. The difference (Δ) of limb-idleness index (LII) at the time of post-injury and pre-injury states was calculated. Biomechanical test of tendons was also performed at week 8 post-injection.

RESULTS

HFD aggravated CI tendon injury with an increase in vascularity and cellularity compared to SC treatment. The histopathological score (week 2: p = 0.025; week 8: p = 0.013) and ΔLII (week 2: p = 0.012; week 8: p = 0.005) were significantly higher in the HFD group compared to those in the SC group after CI tendon injury. Stiffness (saline: p = 0.003; CI: p = 0.010), ultimate stress (saline: p < 0.001; CI: p = 0.006), and Young's modulus (saline: p = 0.017; CI: p = 0.007) were significantly lower in the HFD group compared to the SC group at week 8 after saline or collagenase injection. HFD induced higher expression of IL-1β (week 2: p = 0.010; week 8: p = 0.025) and MMP-1 (week 2: p = 0.010; week 8: p = 0.004) compared to SC treatment after CI tendon injury at both time points.

CONCLUSIONS

HFD-induced obesity exacerbated histopathological, functional, and biomechanical changes in the CI tendon injury model, which was associated with an upregulation of IL-1β and MMP-1.

Characteristics of patients seeking national health service (NHS) care for Achilles tendinopathy: A service evaluation of 573 patients

BACKGROUND

Achilles tendinopathy is a common condition that is often still symptomatic 10 years after onset. Much of the available research has focussed on active populations, however our experience is patients seeking care in the UK's National Health Service (NHS) may be different.

OBJECTIVES

To determine the characteristics of patients receiving NHS care for Achilles tendinopathy (AT). To describe the utilisation of resources and the effectiveness of AT management in the NHS.

METHODS

A data extraction tool was developed and used to retrospectively extract the characteristics of 573 patients diagnosed with Achilles tendinopathy.

RESULTS

NHS Achilles tendinopathy patients averaged 57 years old, had a Body Mass Index of 31, and 69% had at least one other long-term health condition. These included musculoskeletal complaints (59%), hypertension (30%), Chronic Obstructive Pulmonary Disease or asthma (17%), cardiovascular disease (13%) and diabetes (13%). Subsequently medication usage was higher than the general population and included drugs that have been linked to the pathogenesis of tendinopathy. On average, healthcare providers conducted 3.8 therapy sessions and 26% of patients had radiological investigations. Outcome measures were commonly absent with Visual Analog Scale (VAS) scores documented in 51% of records, and patient-reported outcome measures like VISA-A only appearing in 3% of cases. Reports on psychosocial factors were seldom documented.

CONCLUSION

Individuals diagnosed with Achilles tendinopathy through NHS services exhibit distinct characteristics that diverge considerably from those currently represented in the published research used to develop clinical guidelines. NHS Achilles tendinopathy patients have multiple long-term health conditions and higher medication usage.

Upregulation of FABP4 induced inflammation in the pathogenesis of chronic tendinopathy

Objectives

Excessive inflammation contributes to the pathogenesis of tendinopathy. Fatty acid binding protein 4 (FABP4) is a pro-inflammatory adipokine mediating various metabolic and inflammatory diseases. This study aimed to examine the expression of FABP4 and its association with the expressions of inflammatory cytokines in tendinopathy. The effects of a single injection of FABP4 on tendon pathology and inflammation were examined. The effect of FABP4 on the expressions of inflammatory cytokines and the effect of IL-1β on the expression of FABP4 in tendon-derived stem/progenitor cells (TDSCs) were also investigated.

Methods

1) Clinical patellar tendinopathy samples, healthy hamstring tendon samples, and healthy patellar tendon samples, 2) rotator cuff tendinopathy samples and healthy hamstring tendon samples; and 3) Achilles tendons of mice after saline or collagenase injection (CI) were stained for FABP4, IL-1β, IL-6, TNF-α and IL-10 by immunohistochemistry (IHC). For the rotator cuff tendinopathy samples, co-localization of FABP4 with IL-1β and TNF-α was done by immunofluorescent staining (IF). Mouse Achilles tendons injected with FABP4 or saline were collected for histology and IHC as well as microCT imaging post-injection. TDSCs were isolated from human and mouse tendons. The mRNA expressions of inflammatory cytokines in human and mouse TDSCs after the addition of FABP4 was quantified by qRT-PCR. The expression of FABP4 in TDSCs isolated from rotator cuff tendinopathy samples and healthy hamstring tendon samples was examined by IF. Mouse Achilles TDSCs were treated with IL-1β. The mRNA and protein expressions of FABP4 were examined by qRT-PCR and IF, respectively.

Results

There was significant upregulation of FABP4 in the patellar tendinopathy samples and rotator cuff tendinopathy samples compared to their corresponding controls. FABP4 was mainly expressed in the pathological areas including blood vessels, hypercellular and calcified regions. The expressions of IL-1β and TNF-α increased in human rotator cuff tendinopathy samples and co-localized with the expression of FABP4. Collagenase induced tendinopathic-like histopathological changes and ectopic calcification in the mouse Achilles tendinopathy model. The expressions of inflammatory cytokines (IL-1β, IL-6, TNF-α, IL-10) and FABP4 increased in hypercellular region, round cells chondrocyte-like cells and calcified regions in the mouse Achilles tendons post-collagenase injection. A single injection of FABP4 in mouse Achilles tendons induced histopathological changes resembling tendinopathy, with increased cell rounding, loss of collagen fiber alignment, and additionally presence of chondrocyte-like cells and calcification post-injection. The expressions of IL1-β, IL-6, TNF-α and IL-10 increased in mouse Achilles tendons post-FABP4 injection. FABP4 increased the expressions of IL10, IL6, and TNFa in human TDSCs as well as the expressions of Il1b, Il6, and Il10 in mouse TDSCs. Human tendinopathy TDSCs expressed higher level of FABP4 compared to healthy hamstring TDSCs. Besides, IL-1β increased the expression of FABP4 in mouse TDSCs.

Conclusion

In conclusion, an upregulation of FABP4 is involved in excessive inflammation and pathogenesis of tendinopathy. TDSCs is a potential source of FABP4 during tendon inflammation.

Translation potential of this article

FABP4 can be a potential treatment target of tendinopathy.

Influence of body mass index on severity of rotator cuff tears

BACKGROUND

Research on the relationship between obesity and rotator cuff tears (RCTs) has been limited to the impact of obesity on the results of arthroscopic repair of RCTs; thus, a need for rigorous research controlling for other factors affecting RCTs is warranted, especially to better understand the impact of body mass index (BMI) on RCT severity.

METHODS

A retrospective study of admission records contained in electronic medical records pertaining to patients who were admitted for RCT repair on 1 shoulder between January 2018 and July 2022 was conducted. In total, 386 patients were included. In accordance with guidance regarding obesity from Taiwan's Ministry of Health and Welfare, patients were divided into three groups: underweight or normal weight (BMI <24.0 kg/m2), overweight (BMI 24.0-26.9 kg/m2), or obese (BMI ≥27.0 kg/m2). Magnetic resonance imaging was used to assess RCT severity in terms of four parameters: Patte stage (PS), fatty infiltration (FI), anteroposterior tear size (AP), and retraction size. Multinomial logistic regression analysis was performed on PS and FI grade data, and multiple linear regression analysis was performed on AP tear size and retraction size in order to analyze impact.

RESULTS

Our results revealed that the average age of the 386 patients was 63.41 years (SD = 9.29) and the mean BMI was 25.88 (SD = 3.72) kg/m2. We found significant differences in PS (P = .003), FI (P < .001), retraction size (P = .001), and AP tear size (P = .001) among patients who were underweight or normal weight, overweight, and obese. After controlling for other risk factors, including age, gender, RCT-prone occupation, duration of shoulder pain prior to surgery, history of shoulder injury, and tobacco use, we found that obese patients had higher severity levels in PS (B = 1.21, OR = 3.36, P = .029), FI (B = 1.38, OR = 3.96, P < .001), retraction size (β = 0.18, P = .001), and AP tear size (β = 0.18, P = .001) compared to underweight or normal weight patients.

CONCLUSIONS

Our study demonstrates that a correlation exists between BMI-measured obesity and RCT severity. We therefore suggest that adults control their weight given that maintaining a healthy weight is highly associated with better shoulder health.

Possible relationship between the gut leaky syndrome and musculoskeletal injuries: the important role of gut microbiota as indirect modulator

This article aims to examine the evidence on the relationship between gut microbiota (GM), leaky gut syndrome and musculoskeletal injuries. Musculoskeletal injuries can significantly impair athletic performance, overall health, and quality of life. Emerging evidence suggests that the state of the gut microbiota and the functional intestinal permeability may contribute to injury recovery. Since 2007, a growing field of research has supported the idea that GM exerts an essential role maintaining intestinal homeostasis and organic and systemic health. Leaky gut syndrome is an acquired condition where the intestinal permeability is impaired, and different bacteria and/or toxins enter in the bloodstream, thereby promoting systemic endotoxemia and chronic low-grade inflammation. This systemic condition could indirectly contribute to increased local musculoskeletal inflammation and chronificate injuries and pain, thereby reducing recovery-time and limiting sport performance. Different strategies, including a healthy diet and the intake of pre/probiotics, may contribute to improving and/or restoring gut health, thereby modulating both systemically as local inflammation and pain. Here, we sought to identify critical factors and potential strategies that could positively improve gut microbiota and intestinal health, and reduce the risk of musculoskeletal injuries and its recovery-time and pain. In conclusion, recent evidences indicate that improving gut health has indirect consequences on the musculoskeletal tissue homeostasis and recovery through the direct modulation of systemic inflammation, the immune response and the nociceptive pain.

Effect of Diabetes on Tendon Structure and Function: Not Limited to Collagen Crosslinking

Diabetes mellitus (DM) is associated with musculoskeletal complications-including tendon dysfunction and injury. Patients with DM show altered foot and ankle mechanics that have been attributed to tendon dysfunction as well as impaired recovery post-tendon injury. Despite the problem of DM-related tendon complications, treatment guidelines specific to this population of individuals are lacking. DM impairs tendon structure, function, and healing capacity in tendons throughout the body, but the Achilles tendon is of particular concern and most studied in the diabetic foot. At macroscopic levels, asymptomatic, diabetic Achilles tendons may show morphological abnormalities such as thickening, collagen disorganization, and/or calcific changes at the tendon enthesis. At smaller length scales, DM affects collagen sliding and discrete plasticity due to glycation of collagen. However, how these alterations translate to mechanical deficits observed at larger length scales is an area of continued investigation. In addition to dysfunction of the extracellular matrix, tendon cells such as tenocytes and tendon stem/progenitor cells show significant abnormalities in proliferation, apoptosis, and remodeling capacity in the presence of hyperglycemia and advanced glycation end-products, thus contributing to the disruption of tendon homeostasis and healing. Improving our understanding of the effects of DM on tendons-from molecular pathways to patients-will progress toward targeted therapies in this group at high risk of foot and ankle morbidity.

Chronic post-traumatic pain: rheumatological and orthopedic aspects

Trauma causes a complex local and systemic reaction of the macroorganism, the consequences of which can be various functional, neurological and psychoemotional disorders. One of the most painful complications of injuries of the musculoskeletal system is chronic post-traumatic pain (CPTP), which occurs, depending on the severity of the damage, in 10–50% of cases. The pathogenesis of this syndrome is multifactorial and includes the development of chronic inflammation, degenerative changes (fibrosis, angiogenesis, heterotopic ossification), pathology of the muscular and nervous systems, neuroplastic changes leading to the development of central sensitization, as well as depression, anxiety and catastrophization. Risk factors for CPTP should be considered the severity of injury, comorbid diseases and conditions (in particular, obesity), stress and serious trauma-related experiences (within the framework of post-traumatic stress disorder), the development of post-traumatic osteoarthritis and chronic tendopathy, genetic predisposition, deficiencies in treatment and rehabilitation in the early period after injury. To date, there is no clear system of prevention and treatment of CPTP. Considering the pathogenesis of this suffering, adequate anesthesia after injury, active anti–inflammatory therapy (including local injections of glucocorticoids), the use of hyaluronic acid, slow-acting symptomatic agents and autologous cellular preparations – platelet-riched plasma, mesenchymal stem cells, etc. are of fundamental importance. However, therapeutic and surgical methods of CPTP control require further study

Flavonoids from Lycium barbarum leaves attenuate obesity through modulating glycolipid levels, oxidative stress, and gut bacterial composition in high-fat diet-fed mice

Traditional herbal therapy made from Lycium barbarum leaves has been said to be effective in treating metabolic diseases, while its exact processes are yet unknown. Natural flavonoids are considered as a secure and reliable method for treating obesity. We thus made an effort to investigate the processes by which flavonoids from L. barbarum leaves (LBLF) reduce obesity. To assess the effectiveness of the intervention following intragastric injection of various dosages of LBLF (50, 100, and 200 mg/kg⋅bw), obese model mice developed via a high-fat diet were utilized. Treatment for LBLF may decrease body weight gain, Lee’s index, serum lipids levels, oxidative stress levels, and hepatic lipids levels. It may also enhance fecal lipids excretion and improve glucose tolerance. Additionally, LBLF therapy significantly restored gut dysfunction brought on by a high-fat diet by boosting gut bacterial diversities and altering the composition of the gut bacterial community by elevating probiotics and reducing harmful bacteria.

Roles of Oxidative Stress in Acute Tendon Injury and Degenerative Tendinopathy-A Target for Intervention

Both acute and chronic tendon injuries are disabling sports medicine problems with no effective treatment at present. Sustained oxidative stress has been suggested as the major factor contributing to fibrosis and adhesion after acute tendon injury as well as pathological changes of degenerative tendinopathy. Numerous in vitro and in vivo studies have shown that the inhibition of oxidative stress can promote the tenogenic differentiation of tendon stem/progenitor cells, reduce tissue fibrosis and augment tendon repair. This review aims to systematically review the literature and summarize the clinical and pre-clinical evidence about the potential relationship of oxidative stress and tendon disorders. The literature in PubMed was searched using appropriate keywords. A total of 81 original pre-clinical and clinical articles directly related to the effects of oxidative stress and the activators or inhibitors of oxidative stress on the tendon were reviewed and included in this review article. The potential sources and mechanisms of oxidative stress in these debilitating tendon disorders is summarized. The anti-oxidative therapies that have been examined in the clinical and pre-clinical settings to reduce tendon fibrosis and adhesion or promote healing in tendinopathy are reviewed. The future research direction is also discussed.

Causal Associations of Obesity With Achilles Tendinopathy: A Two-Sample Mendelian Randomization Study

BACKGROUND

Achilles tendinopathy (AT) is associated with severe pain and is the cause of dysfunction and disability that are associated with significant reduction in social and economic benefits. Several potential risk factors have been proposed to be responsible for AT development; however, the results of observational epidemiological studies remain controversial, presumably because the designs of these studies are subject to residual confounding and reverse causality. Mendelian randomization (MR) can infer the causality between exposure and disease outcomes using genetic variants as instrumental variables, and identification of the causal risk factors for AT is beneficial for early intervention. Thus, we employed the MR strategy to evaluate the causal associations between previously reported risk factors (anthropometric parameters, lifestyle factors, blood biomarkers, and systemic diseases) and the risk of AT.

METHODS

Univariable MR was performed to screen for potential causal associations between the putative risk factors and AT. Bidirectional MR was used to infer reverse causality. Multivariable MR was conducted to investigate the body mass index (BMI)-independent causal effect of other obesity-related traits, such as the waist-hip ratio, on AT.

RESULTS

Univariable MR analyses with the inverse-variance weighted method indicated that the genetically predicted BMI was significantly associated with the risk of AT (P=2.0×10^-3), and the odds ratios (95% confidence intervals) is 1.44 (1.14-1.81) per 1-SD increase in BMI. For the other tested risk factors, no causality with AT was identified using any of the MR methods. Bidirectional MR suggested that AT was not causally associated with BMI, and multivariable MR indicated that other anthropometric parameters included in this study were not likely to causally associate with the risk of AT after adjusting for BMI.

CONCLUSIONS

The causal association between BMI and AT risk suggests that weight control is a promising strategy for preventing AT and alleviating the corresponding disease burden.