Neoangiogenesis is reduced in chronic tendinopathies of type 2 diabetic patients

Perioperative glycemic control reduces the risk of retear in diabetic patients following arthroscopic rotator cuff repair: A meta-analysis

BACKGROUND

Previous studies have associated diabetes with reduced shoulder motion, increased pain, and higher postoperative retear risk after arthroscopic rotator cuff repair (ARCR). However, the impact of glycemic control, measured by hemoglobin A1c (HbA1c) levels, on retear and revision rates after ARCR in diabetic patients remains unclear.

METHODS

This systematic review was conducted using the PubMed, Cochrane Library, Web of Science, and Embase databases according to the preferred reporting conventions for systematic reviews and meta-analyses. Only studies that compared retears and revisions in ARCR patients with documented HbA1c levels between controlled and uncontrolled diabetes groups were included. Relevant data were extracted and analyzed using STATA software. The methodological index for nonrandomized studies was employed to assess the risk of bias in the selected studies. Additionally, heterogeneity tests and sensitivity analyses were conducted to evaluate potential heterogeneity within the samples, and publication bias was also detected.

RESULTS

Six studies (4395 patients), including five retrospective cohort studies and one case‒control study, were included. Four of these studies assessed retears involving 253 patients. Lower HbA1c levels, indicating better glycemic control, were significantly associated with reduced retear rates after ARCR in diabetic patients (P = 0.000; odds ratio = 0.242, 95 % confidence interval: 0.128-0.454; I2 = 25 %). For revision evaluations, two studies, with a total of 4142 patients, found no significant difference in rates between controlled and uncontrolled diabetes groups, and no publication bias was detected.

CONCLUSION

Following ARCR in diabetic patients, effective glycemic control significantly reduces retear rates without affecting revisions, and maintaining glycemic control in the postoperative period may contribute to rotator cuff healing.

Elevated HbA1c is not associated with reoperation following arthroscopic rotator cuff repair in patients with diabetes mellitus

BACKGROUND

Hyperglycemia is a known risk factor for tendon degeneration due to oxidative stresses from production of advanced glycosylation end products. In patients with diabetes mellitus (DM), analysis of glycated hemoglobin (HbA1c) provides a 3-month window into a patient's glucose control. No guidelines exist for ideal preoperative HbA1c and glucose control prior to arthroscopic rotator cuff repair. This study evaluated if a critical HbA1c level is associated with reoperation following arthroscopic rotator cuff repair.

METHODS

We retrospectively evaluated patients with DM who underwent primary arthroscopic rotator cuff repair from January 2014 to December 2018 at a single institution. Patients required a preoperative HbA1c within 3 months of surgery. Medical records were queried to evaluate for reoperation and identify the subsequent procedures performed. Univariate statistical analysis was performed to assess factors associated with reoperation (P < .05 considered significant). Threshold, area under the curve (AUC), analysis was performed to assess if a critical HbA1c value was associated with reoperation.

RESULTS

A total of 402 patients met inclusion criteria. Patients had an average age of 65.5 years (range 40-89) at time of surgery; 244 (60.6%) patients were male; and average body mass index was 32.96 ± 5.81. Mean HbA1c was 7.36 (range 5.2-12). Thirty-three patients (8.2%) underwent subsequent reoperation. Six patients (1.5%) underwent capsular release and lysis of adhesions, 20 patients (5.0%) underwent a revision rotator cuff surgery, combination revision rotator cuff repair and lysis of adhesions, graft-augmented revision repair, or superior capsular reconstruction, and 7 patients (1.7%) underwent revision to reverse shoulder arthroplasty (1.7%). There were no cases of reoperation for infection. On AUC analysis, no critical HbA1c value was identified to predispose to reoperation. Interestingly, elevated preoperative American Society of Anesthesiologists (ASA) physical status classification score (2.8 vs. 2.28, P = .001) was associated with a higher reoperation rate.

DISCUSSION

In patients with DM, preoperative HbA1c is not a predictive factor for surgical failure requiring reoperation. Stable glycemic control is important to a patient's overall health and may play a role in minimizing postoperative medical complications, but an elevated preoperative HbA1c should not be a strict surgical contraindication for arthroscopic rotator cuff repair. In patients with DM, an elevated ASA score is associated with an increased rate of subsequent reoperation; diabetic patients should be counseled accordingly.

Effects of adipose-derived mesenchymal stem cell conditioned medium on human tenocytes exposed to high glucose

Introduction

Diabetic tendinopathy is a common invalidating and challenging disease that may be treated using stem cells. However, the effects of adipose-derived mesenchymal stem cell conditioned medium (ASC-CM) in diabetic tendinopathy have never been explored.

Objectives

The present study evaluated the effects of ASC-CM on morphology, cell viability, structure, and scratch wound closure of human tenocytes (HTNC) exposed to high glucose (HG).

Design

Experimental study.

Methods

HTNC were exposed to HG (25 mM) for 7, 14 and 21 days with or without ASC-CM for the last 24 h. CM was collected from 4 × 105 ASCs, centrifuged for 10 min at 200 g and sterilized with 0.22 μm syringe filter.

Results

At 7 days, HG-HTNC had decreased cell viability [72 ± 2%, p < 0.01 versus normal glucose (NG)] compared to NG-HTNC (90 ± 5%). A further decrement was detected after 14 and 21 days (60 ± 4% and 60 ± 5%, both, p < 0.01 versus NG and p < 0.01 versus HG7). While NG-HTNC evidenced a normal fibroblast cell-like elongated morphology, HG-HTNC showed increased cell roundness. In contrast, HG-HTNC exposed to ASC-CM showed a significant increase in cell viability, an improved cell morphology and higher scratch wound closure at all HG time points. Moreover, the exposure to ASC-CM significantly increased thrombospondin 1 and transforming growth factor beta 1 (TGF-β1) content in HG-HTNC. The TGF-β1 elevation was paralleled by higher Collagen I and Vascular Endothelial Growth Factor in HG-HTNC.

Conclusion

ASC-CM may restore the natural morphology, cell viability and structure of HTNC, promoting their scratch wound closure through TGF-β1 increase.

Isolated adductor longus avulsion in a young semi-professional football player: Imaging contribution and therapeutic considerations

Adductor longus injuries are usually observed at the proximal musculo-tendinous junction, but isolated tendinous ruptures (i.e., avulsion) at the origin on the pubic bone are uncommon. In this article, we report a new case of isolated adductor longus avulsion that occurred in a young athlete and was treated with conservative therapy. An 18 years old semi-professional football player, in the attempt to reach the ball with his right leg, reported acute pain and functional limitation in his left adductor area. Clinical examination showed tenderness on palpation associated with mild swelling. Manual strength testing of adductor muscles showed weakness and elicited moderate pain in the proximal groin region near the pubic bone. The diagnostic evaluations (ultrasound [3-14 MHz linear probe] and magnetic resonance imaging [1.5 Tesla magnetic field]), performed a few days after the event, showed a complete isolated avulsion of the proximal adductor longus tendon associated with a fluid collection, with a gap of about 9.5 mm from its insertion on the pubic bone. Degenerative alterations (sub-chondral sclerosis, bone edema, erosions, cortical irregularities, calcifications) were found. These findings were crucial in the treatment choice because conservative management is suggested when the gap is below 1 cm and when no important displacement of proximal torn tendon's end at dynamic ultrasound is appreciated. A structured rehabilitation protocol was implemented, allowing the player to come back to his full athletic activity after 146 days. Return to play was allowed when several subjective and objective parameters were fully satisfied (full hip range of motion, pain-free football-specific activities, less than a 5%-10% difference in hip adduction strength between the injured and uninjured legs, advanced anatomical healing of the adductor longus tendon seen on diagnostic exams, and Hip And Groin Outcome Score [HAGOS] scores similar to baseline data). This case report emphasizes the importance of diagnostic imaging and clinical assessments in the management of an adductor longus avulsion with short retraction (about 1 cm). Both imaging techniques are non-invasive and without risks, allow contra-lateral examination and may guide in the treatment choice; moreover, they significantly influence the post-care approach by enabling to fine-tune a safe return to full athletic activity with minor re-injury rate. While US can be used as primary imaging modality, MRI offers a higher level of accuracy.

Postoperative HbA1c Level as a Predictor of Rotator Cuff Integrity After Arthroscopic Rotator Cuff Repair in Patients With Type 2 Diabetes

Background

In patients with type 2 diabetes mellitus (DM), preoperative glycosylated hemoglobin (HbA1c) is associated with outcomes after arthroscopic rotator cuff repair (ARCR); however, the relationship between outcomes and postoperative serum glycosylated hemoglobin (HbA1c) after ARCR has not been investigated.

Purpose

To evaluate outcomes after ARCR in patients (1) with and without DM and (2) with DM according to their pre- and postoperative HbA1c levels.

Study Design

Cohort study; Level of evidence, 3.

Method

Included in this study were 148 patients without DM and 35 patients with type 2 DM who underwent ARCR between January 1, 2017, and December 31, 2019. Clinical and radiological outcomes were evaluated preoperatively and at the latest clinical follow-up. Postoperative magnetic resonance imaging was performed after 12 months. In patients with type 2 DM, HbA1c levels were evaluated preoperatively as well as 6 and 12 months postoperatively; patients with an HbA1c level of ≥7% were defined as having uncontrolled DM. Multivariate logistic regression analyses were performed to determine the factors for retears after ARCR.

Results

The retear rates after ARCR were 22.9% (8/35) and 16.9% (25/148) in patients with and without DM, respectively. The retear rates were significantly higher in the 6-month postoperative uncontrolled DM group than in the controlled DM and non-DM groups (50% vs 8.7% and 16.8%; P < .05). The odds ratio for retears in the postoperative uncontrolled DM group was 5.555 (P =0.01) compared with the non-DM group. Among the patients with DM, in the uncontrolled DM group, 6-month postoperative hyperglycemia was superior in accuracy, sensitivity, and specificity for predicting retears after ARCR than preoperative hyperglycemia (77.1% vs 62.9%, 75% vs 37.5%, and 77.8% vs 70.4%, respectively).

Conclusion

This study demonstrated the association between uncontrolled postoperative DM and an increased risk of retears compared with no DM or controlled DM. Furthermore, postoperative HbA1c values were correlated more closely with the risk of retears than preoperative HbA1c values.

Microcirculatory Responses to Muscle and Tendon Exercises in Individuals With and Without Type 2 Diabetes Mellitus and the Association Between Microcirculatory and Exercise Performance

Background: This study aimed to measure and compare (1) the microcirculation and microcirculatory responses of the muscles and tendons at rest and during isometric muscle contractions in participants with and without diabetes mellitus (DM) and (2) to determine correlations between microcirculation and muscle strength. Methods: Sixty-three participants with type 2 DM and 42 physically matched controls were recruited. Baseline measurements of the microcirculation of the rectus femoris (RF) and medial gastrocnemius (MG) muscles and patellar (PT) and Achilles tendons (AT), as well as their microcirculatory changes during maximal isometric exercises, were performed and recorded by using near-infrared spectroscopy and a red laser. Data on various laboratory tests (including glycated hemoglobin, triglyceride, high-density cholesterol), the monofilament test, and the ankle-brachial index were also obtained. Results: The baseline measurements indicated that, compared with the controls, the diabetic participants had lower oxygen saturation (SpO₂) in their RF and MG muscles (both P < 0.001), and the total hemoglobin in the diabetic PT and AT was higher (P = 0.001 and P = 0.01). The minimal SpO₂ levels in the aforementioned muscles during isometric contractions were lower in the diabetes group than in the control group (P ≤ 0.001). Furthermore, there were correlations between the microcirculatory change of the RF muscle and the knee extension force. Conclusions: This study demonstrated the effects of diabetes on the microcirculation of skeletal muscles and tendons during baseline measurements and responses to maximal isometric exercises. The results support the need for preventive strategies for diabetic muscles to prevent adverse complications when performing resistance training.

Sonoelastographic Evaluation of the Achilles Tendon in Patients With Type 2 Diabetes Mellitus

Diabetic foot is one of the dreaded complications of diabetes mellitus (DM). Alterations of the Achilles tendon (AT) may contribute to development of foot ulcers in diabetic patients. We evaluated the sonoelastographic abnormalities of the AT in 61 healthy volunteers and 81 patients with type 2 DM. The patients were further divided into those with and without peripheral neuropathy (PN). The AT thickness was measured in the proximal, middle and distal portions. Alterations in echo pattern were noted. The patients were found to have thicker tendons than the healthy volunteers (p < 0.01). Alterations in the echo pattern of the AT were more common in patients compared with healthy volunteers (p < 0.01). The shear wave velocity in the distal one-third of the AT was measured using shear wave elasticity imaging. Mean shear wave velocity values obtained were lower in patients compared with healthy volunteers (p < 0.001). No significant difference was found in the sonoelastographic findings of the AT in patients with and without PN. We conclude that there is softening, thickening and alterations in echo pattern of the AT in the form of hypoechogenicity, loss of fibrillar pattern and calcification at insertion in patients with type 2 DM, and these alterations could occur independent of onset of PN.

Ultrasonographic Evaluation of Lower Extremity Entheseal Sites in Diabetic Patients Using Glasgow Ultrasound Enthesitis Scoring System Score

Objective

The prevalence of musculoskeletal complications in diabetes mellitus (DM) increases with the duration of disease and with poor glycemic control. Our aim was to evaluate lower extremity musculoskeletal complications in patients with DM using the Glasgow Ultrasound Enthesitis Scoring System, and to reveal the relationship between clinical and sono-graphic findings.

Materials and methods

A total of 67 patients (25 men, 42 women) with DM were included in the study. All the diabetic patients were selected if they did not have any symptom of muscu-loskeletal system in the lower extremities. They were divided into four groups. Ultrasonographic assessment was performed according to the Glasgow Ultrasound Enthesitis Scoring System with an Esaote MyLab 5 device equipped with a 5-13 MHz linear transducer. Correlation between diabetes duration and lower extremity enthesopathy scores were evaluated.

Results

There was a significant correlation between duration of DM and total Glasgow Ultrasound Enthesitis Scoring System scores (p < 0.001). In addition, duration of DM was significantly correlated with enthesophyte scores and erosion scores (both p < 0.001). There was a significant difference among Groups 1 -4 for the mean enthesophyte score and mean erosion score (both, p < 0.001).

Conclusion

Musculoskeletal ultrasonography is an effective, inexpensive, and useful tool without radiation for evaluating diabetic patients for the early diagnosis of musculoskeletal complications.

Tendinopathy in diabetes mellitus patients-Epidemiology, pathogenesis, and management

Chronic tendinopathy is a frequent and disabling musculo-skeletal problem affecting the athletic and general populations. The affected tendon is presented with local tenderness, swelling, and pain which restrict the activity of the individual. Tendon degeneration reduces the mechanical strength and predisposes it to rupture. The pathogenic mechanisms of chronic tendinopathy are not fully understood and several major non-mutually exclusive hypotheses including activation of the hypoxia-apoptosis-pro-inflammatory cytokines cascade, neurovascular ingrowth, increased production of neuromediators, and erroneous stem cell differentiation have been proposed. Many intrinsic and extrinsic risk/causative factors can predispose to the development of tendinopathy. Among them, diabetes mellitus is an important risk/causative factor. This review aims to appraise the current literature on the epidemiology and pathology of tendinopathy in diabetic patients. Systematic reviews were done to summarize the literature on (a) the association between diabetes mellitus and tendinopathy/tendon tears, (b) the pathological changes in tendon under diabetic or hyperglycemic conditions, and (c) the effects of diabetes mellitus or hyperglycemia on the outcomes of tendon healing. The potential mechanisms of diabetes mellitus in causing and exacerbating tendinopathy with reference to the major non-mutually exclusive hypotheses of the pathogenic mechanisms of chronic tendinopathy as reported in the literature are also discussed. Potential strategies for the management of tendinopathy in diabetic patients are presented.

Hormones and tendinopathies: the current evidence

BACKGROUND

Tendinopathies negatively affect the quality of life of millions of people, but we still do not know the factors involved in the development of tendon conditions.

SOURCES OF DATA

Published articles in English in PubMed and Google Scholar up to June 2015 about hormonal influence on tendinopathies onset. One hundred and two papers were included following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

AREAS OF AGREEMENT

In vitro and in vivo, tenocytes showed changes in their morphology and in their functional properties according to hormonal imbalances.

AREAS OF CONTROVERSY

Genetic pattern, sex, age and comorbidities can influence the hormonal effect on tendons.

GROWING POINTS

The increasing prevalence of metabolic disorders prompts to investigate the possible connection between metabolic problems and musculoskeletal diseases.

AREAS TIMELY FOR DEVELOPING RESEARCH

The influence of hormones on tendon structure and metabolism needs to be further investigated. If found to be significant, multidisciplinary preventive and therapeutic strategies should then be developed.

Rehabilitation of Tendon Problems in Patients with Diabetes Mellitus

Exercise is crucial in the management of diabetes mellitus and its associated complications. However, individuals with diabetes have a heightened risk of musculoskeletal problems, including tendon pathologies. Diabetes has a significant impact on the function of tendons due to the accumulation of advanced glycation end-products in the load-bearing collagen. In addition, tendon vascularity and healing may be reduced due to diabetes-induced changes in the peripheral vascular system, and impaired synthesis of collagen and glycosaminoglycan. The current chapter presents an evidence-based discussion of considerations for the rehabilitation of tendon problems in people with diabetes. The following conditions are discussed in detail - calcific tendinopathy, tenosynovitis, tendon rupture, and non-calcifying tendinopathy. Common diabetes-related findings are presented, along with their potential impact on tendinopathy management and suggested modifications to standard tendinopathy treatment protocols. A holistic approach should be used to optimize musculotendinous function, including a comprehensive exercise prescription addressing strength, flexibility, and aerobic fitness.

Extensor Mechanism Injuries of the Knee: Demographic Characteristics and Comorbidities from a Review of 726 Patient Records

BACKGROUND

The purpose of our study was to describe and compare extensor mechanism injuries with regard to age, sex, body mass index (BMI), and comorbidities.

METHODS

We identified patients who had undergone surgical management of an extensor mechanism injury at two institutions between 1986 and 2012. Data analyzed included age at the time of surgery, sex, height, weight, and the presence of medical comorbidities. Patients with chronic disruption of the quadriceps or patellar tendon, those undergoing revision surgery, or those with injuries in the setting of total knee arthroplasty were excluded.

RESULTS

Seven hundred and twenty-six patients were included. There were 427 (58.8%) patellar fractures, 210 (28.9%) quadriceps tendon ruptures, and eighty-nine (12.3%) patellar tendon ruptures. Sixty-seven percent of the patellar fractures occurred in females, while 91% of the quadriceps and 95.5% of the patellar tendon ruptures occurred in males (p < 0.001). Age distribution was significantly different among the groups: the mean patient age (and standard deviation) was 61.0 ± 13.1 years (range, twenty to ninety-two years) for quadriceps tendon rupture, 56.3 ± 17.4 years (range, sixteen to ninety-one years) for patellar fracture, and 39.5 ± 12.2 years (range, eighteen to seventy-two years) for patellar tendon rupture. Patellar fractures showed a bimodal distribution with regard to both age and sex: the median age of females was sixty-two years (range, sixteen to ninety-one years), and the median age of males was forty-seven years (range, sixteen to ninety-one years) (p < 0.001). BMI varied significantly among the cohorts: a mean of 25.0 ± 5.2 kg/m2 for patellar fracture, 28.7 ± 4.97 kg/m2 for patellar tendon rupture, and 30.0 ± 6.05 kg/m2 for quadriceps tendon rupture (p < 0.001). Ninety-six percent of the females with a quadriceps or patellar tendon injury had an underlying medical comorbidity compared with 68% of the males (p = 0.008). Of the patients with underlying comorbidities, 61% of the females had comorbidities that were considered to be risk factors for tendinopathy compared with 34% of the males (p = 0.008).

CONCLUSIONS

Females with an extensor mechanism injury are more likely to sustain a patellar fracture compared with males. Younger males are more likely to sustain a patellar fracture or patellar tendon rupture; however, we found that 43% of the patellar tendon ruptures were in patients over the age of forty. Medical comorbidities were common with tendon ruptures, and we found that they were significantly more common in females than in males.

CLINICAL RELEVANCE

Surgeons treating female patients with a tendinous extensor mechanism disruption should have a low threshold to initiate a medical work-up in search of a possible undiagnosed medical comorbidity.

Alterations of tendons in diabetes mellitus: what are the current findings?

As a connective tissue, tendon connects the muscle and bone, and plays the key role in the locomotor system. Some previous studies have shown the pathological alternations in diabetic tendons, which might result in the structural and functional changes, and even accelerate the process of diabetic foot. In this review, we examined the current findings of the diabetic tendons in the form of various aspects, and summarized the clinical presentation, imaging, biomechanical, histopathological, cellular and molecular abnormalities in the diabetic tendons. The progress of diabetic tendon damage is complicated and the main hypotheses include the excessive accumulation of AGEs, the altered inflammatory response, neovascularization and insensitive neuropathy. However, the cellular and molecular mechanisms of these alterations are still ambiguous. Tendon stem/progenitor cells (TSPCs) have been discovered to play important roles in both tendon physiology and tendon pathology. Recently, we identified TSPCs from patellar tendons in our well-established diabetic rat model and found impaired tenogenic differentiation potential of these cells. We proposed a new hypothesis that the impaired cell functions of diabetic TSPCs might be the underlying cellular and molecular mechanism of the diabetic tendon alternations. These findings should be helpful to establish a better therapeutic strategy for diabetic tendon repair and regeneration.

Achilles tendons in people with type 2 diabetes show mildly compromised structure: an ultrasound tissue characterisation study

BACKGROUND

Musculotendinous overuse injuries are prevalent in people with type 2 diabetes. Non-enzymatic glycosylation of collagen resulting in tendon stiffening may play a role. In this case-control study we determined whether patients with diabetes had poorer ultrasonographic structure in their Achilles tendons compared to age-matched controls.

METHODS

People with type 1 diabetes or type 2 diabetes, and age-matched controls, had computerised ultrasound tissue characterisation of both Achilles tendons. In contiguous ultrasonographic images of the tendon, echopatterns were quantified and categorised into four echo-types. Tendon abnormality was quantified as sum of echo-types III+IV. Furthermore, skin autofluorescence (AF) of the forearm (AF-value) was gathered.

RESULTS

Twenty four type 2 diabetes patients, 24 controls, 24 type 1 diabetes patients and 20 controls were included. AF-value was higher in type 1 diabetes (1.55±0.17) than in their controls (1.39±0.18, p<0.001) and in type 2 diabetes (2.28±0.38) compared to their controls (1.84±0.32, p<0.001) Achilles tendons of type 2 diabetes patients contained more echo-types III+IV (14.1±7.9%) than matched controls (8.0±5.4%, p<0.001). There was a trend towards a difference in echo-types III+IV between type 1 diabetes patients (9.5±5.3%) and their controls (6.5±3.7%, p=0.055). In a stepwise linear regression analysis, body mass index (BMI) was moderately associated with tendon abnormality in patients with diabetes and controls (β=0.393, p<0.001).

CONCLUSIONS

Type 2, and possibly type 1, diabetes patients showed poorer ultrasonographic Achilles tendon structure that may be a risk factor for tendinopathy. Although markers for accumulation of advanced glycation end products were elevated in both diabetes populations, only BMI was associated with these abnormalities.

TRIAL REGISTRATION NUMBER

NTR2209.

Experimental diabetes induces structural, inflammatory and vascular changes of Achilles tendons

This study aims to demonstrate how the state of chronic hyperglycemia from experimental Diabetes Mellitus can influence the homeostatic imbalance of tendons and, consequently, lead to the characteristics of tendinopathy. Twenty animals were randomly divided into two experimental groups: control group, consisting of healthy rats and diabetic group constituted by rats induced to Diabetes Mellitus I. After twenty-four days of the induction of Diabetes type I, the Achilles tendon were removed for morphological evaluation, cellularity, number and cross-sectional area of blood vessel, immunohistochemistry for Collagen type I, VEGF and NF-κB nuclear localization sequence (NLS) and nitrate and nitrite level. The Achilles tendon thickness (µm/100g) of diabetic animals was significantly increased and, similarly, an increase was observed in the density of fibrocytes and mast cells in the tendons of the diabetic group. The average number of blood vessels per field, in peritendinous tissue, was statistically higher in the diabetic group 3.39 (2.98) vessels/field when compared to the control group 0.89 (1.68) vessels/field p = 0.001 and in the intratendinous region, it was observed that blood vessels were extremely rare in the control group 0.035 (0.18) vessels/field and were often present in the tendons of the diabetic group 0.89 (0.99) vessels/field. The immunohistochemistry analysis identified higher density of type 1 collagen and increased expression of VEGF as well as increased immunostaining for NFκB p50 NLS in the nucleus in Achilles tendon of the diabetic group when compared to the control group. Higher levels of nitrite/nitrate were observed in the experimental group induced to diabetes. We conclude that experimental DM induces notable structural, inflammatory and vascular changes in the Achilles tendon which are compatible with the process of chronic tendinopathy.

Occurrence of tendon pathologies in metabolic disorders

This article reviews the pathogenetic role of metabolic disorders, which are of paramount relevance to the progression of tendon damage. In diabetes, the prevalence of rheumatological diseases is high, mainly because of the deleterious effects of advanced glycation end products that deteriorate the biological and mechanical functions of tendons and ligaments. In heterozygous familial hypercholesterolaemia, most patients develop Achilles xanthomatosis, a marker of high risk for cardiovascular disease caused by cholesterol deposition in the tendons. Tendon degeneration has also been observed in non-familial hypercholesterolaemia. Monosodium urate crystal deposition in soft tissues is a hallmark of chronic gouty arthritis. In this group of diseases, the mobilization of cholesterol and uric acid crystals is presumably followed by low-grade inflammation, which is responsible for tendon degeneration. Adiposity may contribute to tendon disorders via two different mechanisms: increased weight on the load-bearing tendons and systemic dysmetabolic factors that trigger subclinical persistent inflammation. Finally, tendon abnormalities have been observed in some rare congenital metabolism disorders such as alkaptonuria.

Management of limited joint mobility in diabetic patients

Several rheumatologic manifestations are more pronounced in subjects with diabetes, ie, frozen shoulder, rotator cuff tears, Dupuytren's contracture, trigger finger, cheiroarthropathy in the upper limb, and Achilles tendinopathy and plantar fasciitis in the lower limb. These conditions can limit the range of motion of the affected joint, thereby impairing function and ability to perform activities of daily living. This review provides a short description of diabetes-related joint diseases, the specific pathogenetic mechanisms involved, and the role of inflammation, overuse, and genetics, each of which activates a complex sequence of biochemical alterations. Diabetes is a causative factor in tendon diseases and amplifies the damage induced by other agents as well. According to an accepted hypothesis, damaged joint tissue in diabetes is caused by an excess of advanced glycation end products, which forms covalent cross-links within collagen fibers and alters their structure and function. Moreover, they interact with a variety of cell surface receptors, activating a number of effects, including pro-oxidant and proinflammatory events. Adiposity and advanced age, commonly associated with type 2 diabetes mellitus, are further pathogenetic factors. Prevention and strict control of this metabolic disorder is essential, because it has been demonstrated that limited joint motion is related to duration of the disease and hyperglycemia. Several treatments are used in clinical practice, but their mechanisms of action are not completely understood, and their efficacy is also debated.

Recombinant human adiponectin as a potential protein for treating diabetic tendinopathy promotes tenocyte progenitor cells proliferation and tenogenic differentiation in vitro

Adiponectin is an adipocyte-secreting hormone that increases cell sensitivity to insulin. It has been previously demonstrated that this hormone protects against Type II Diabetes and, is found to concurrently promote cell proliferation and differentiation. It is postulated that diabetic patients who suffer from tendinopathy may benefit from using adiponectin, which not only improves the metabolism of diabetic ridden tenocytes but also promotes progenitor cell proliferation and differentiation in tendons. These changes may result in tendon regeneration, which, in diabetic tendinopathy, is difficult to treat. Considering that such findings have yet to be demonstrated, a study was thus conducted using diabetic ridden human tenocyte progenitor cells (TPC) exposed to recombinant adiponectin in vitro. TPC were isolated from tendons of diabetic patients and exposed to 10 μg/ml adiponectin. Cell proliferation rate was investigated at various time points whilst qPCR were used to determine the tenogenic differentiation potential. The results showed that adiponectin significantly reduced blood glucose in animal models. The proliferation rate of adiponectin-treated TPCs was significantly higher at 6, 8 and 10 days as compared to untreated cells (p<0.05). The levels of tenogenic genes expression (collagen I, III, tenomodulin and scleraxis) were also significantly upregulated; whilst the osteogenic (Runx2), chondrogenic (Sox9) and adipogenic (PPARУγ) gene expressions remained unaltered. The results of this study suggest that adiponectin is a potential promoter that not only improves diabetic conditions, but also increases tendon progenitor cell proliferation and differentiation. These features supports the notion that adiponectin may be potentially beneficial in treating diabetic tendinopathy.