A systematic review of the histological and molecular changes in rotator cuff disease

Exploring cellular changes in ruptured human quadriceps tendons at single-cell resolution

Tendon ruptures in humans have often been studied during the chronic phase of injury, particularly in the context of rotator cuff disease. However, the early response to acute tendon ruptures remains less investigated. Quadriceps tendons, which require prompt surgical treatment, offer a model to investigate this early response. Therefore, this study aimed to explore the early cellular changes in ruptured compared to healthy human quadriceps tendons. Quadriceps tendon samples were collected from patients undergoing fracture repair (healthy) or tendon repair surgery (collected 7-8 days post-injury). Nuclei were isolated for single-nucleus RNA sequencing, and comprehensive transcriptomic analysis was conducted. The transcriptomes of 12,808 nuclei (7268 from healthy and 5540 from ruptured quadriceps tendons) were profiled, revealing 12 major cell types and several cell subtypes and states. Rupture samples showed increased expression of genes related to extracellular matrix organisation and cell cycle signalling, and a decrease in expression of genes in lipid metabolism pathways. These changes were predominantly driven by gene expression changes in the fibroblast, vascular endothelial cell (VEC), mural cell, and macrophage populations: fibroblasts shift to an activated phenotype upon rupture and there is an increase in the proportion of capillary and dividing VECs. A diverse immune environment was observed, with a shift from homeostatic to activated macrophages following rupture. Cell-cell interactions increased in number and diversity in rupture, and primarily involved fibroblast and VEC populations. Collectively, this transcriptomic analysis suggests that fibroblasts and endothelial cells are key orchestrators of the early injury response within ruptured quadriceps tendon. KEY POINTS: Tendon ruptures in humans have regularly been studied during the chronic phase of injury, but less is known about the early injury response after acute tendon ruptures. This study explored the early cellular changes in ruptured compared to healthy human quadriceps tendons at single-cell resolution. Fibroblasts and endothelial cells seem to be the key orchestrators of the early injury response within ruptured quadriceps tendon. Therefore, these cell types are obvious targets for interventions to enhance tendon healing. Overall, this study highlights that the development of more effective therapeutic options for tendon injury requires better understanding of the cellular, extracellular, and mechanical landscape of tendon tissue.

Risk factors for rotator cuff tear in Syrian adults: a cross-sectional study

Rotator cuff tears (RCTs) are a common shoulder condition, particularly prevalent among older individuals, even though there is limited data regarding the risk factors associated with RCT patients. This research aimed to analyze factors impact on the RCT among the Syrian population. This cross-sectional study utilized a self-administered questionnaire to gather detailed information about RCT and their individual and physical characteristics across eight orthopedic and rehabilitation centers in four provinces of Syria: Damascus, Aleppo, Homs, and Latakia. This data collection occurred from October 2021 to November 2022, with two centers chosen from each province. We assessed participants' background factors, conducted physical examinations, and performed ultrasonographic evaluations on both shoulders. The study included 236 participants (totaling 472 shoulders), comprising 107 males and 129 females (P = 0.04), with an average age of 58.5 years. Among those presenting with current symptoms, 41.2% were diagnosed with rotator cuff tears (RCT), while 58.7% did not exhibit these tears (P = 0.02). Additionally, 26.3% of asymptomatic individuals were found to have RCT, with 73.7% showing no signs of these tears (P = 0.004). Rotator cuff tears were primarily associated with advanced age, male gender, involvement of the dominant arm, engagement in heavy labor, a history of trauma, a positive impingement sign, reduced active forward elevation, and decreased muscle strength in the abduction and external rotation. Logistic regression analysis identified a history of trauma, the dominance of the affected arm, and age as significant risk factors for the occurrence of RCT. The odds ratios for a history of trauma were 2.74 (95% CI 2.36-2.92); for the dominant arm, it was 2.25 (95% CI 2.10-2.68), and for age, it was 1.76 (95% CI 1.82-2.04). This study identifies key risk factors for RCT in Syrian patients, including trauma history, arm dominance, and age. It highlights the interplay of internal and external factors in symptomatic and asymptomatic tears, with diagnostic indicators like positive impingement signs aiding early detection and management.

The elastic properties of the tendinous and capsular layers of the rotator cuff complex using fresh tissue-a biomechanical study

BACKGROUND

Elastic modulus is an important biomechanical component that indicates stiffness or elasticity of biological material. Recently the use of digital image correlation (DIC) in elastic modulus studies on fresh tissue has shown great accuracy in estimating elastic properties; thus, the aim of this study was to investigate the elasticity of capsular and tendinous layers of the rotator cuff complex employing this method.

MATERIALS AND METHODS

The supraspinatus, infraspinatus, and subscapularis from eight (n = 8) fresh/frozen tissue shoulders were reverse dissected from their origins. The muscles were separated from one another and dissected to produce 20 × 20 mm tendinous and capsular strips for each muscle. DIC was employed to measure the strain of the tendinous and capsular portions of each of the muscles during tensile testing, and tangent elastic modulus values were obtained.

RESULTS

The tendinous layers for supraspinatus, infraspinatus, and subscapularis yielded higher average tangent elastic moduli readings (62.1 MPa, 67.1 MPa, and 59.6 MPa, respectively) compared to their capsular counterparts (29.0 MPa, 32.5 MPa, and 41.5 MPa, respectively).

CONCLUSION

Different elastic moduli findings for the tendinous and capsular layers suggest these layers should be considered independently during surgical repair to avoid biomechanical imbalance which may result if these layers were to be repaired as one singular layer.

Diseased Tendon Models Demonstrate Influence of Extracellular Matrix Alterations on Extracellular Vesicle Profile

Tendons enable movement through their highly aligned extracellular matrix (ECM), predominantly composed of collagen I. Tendinopathies disrupt the structural integrity of tendons by causing fragmentation of collagen fibers, disorganization of fiber bundles, and an increase in glycosaminoglycans and microvasculature, thereby driving the apparent biomechanical and regenerative capacity in patients. Moreover, the complex cellular communication within the tendon microenvironment ultimately dictates the fate between healthy and diseased tendon, wherein extracellular vesicles (EVs) may facilitate the tendon's fate by transporting biomolecules within the tissue. In this study, we aimed to elucidate how the EV functionality is altered in the context of tendon microenvironments by using polycaprolactone (PCL) electrospun scaffolds mimicking healthy and pathological tendon matrices. Scaffolds were characterized for fiber alignment, mechanical properties, and cellular activity. EVs were isolated and analyzed for concentration, heterogeneity, and protein content. Our results show that our mimicked healthy tendon led to an increase in EV secretion and baseline metabolic activity over the mimicked diseased tendon, where reduced EV secretion and a significant increase in metabolic activity over 5 days were observed. These findings suggest that scaffold mechanics may influence EV functionality, offering insights into tendon homeostasis. Future research should further investigate how EV cargo affects the tendon's microenvironment.

Supraspinatus Muscle and Tendon Characteristics 1 Year After Surgical Rotator Cuff Repair Compared With Contralateral Shoulder: Data From the CUT-N-MOVE Trial

BACKGROUND

It is necessary to better understand the structural characteristics of the supraspinatus tendon and associated muscle after rotator cuff repair and in the event of retear.

PURPOSE

To study structural differences between the repaired and contralateral shoulders 1 year after rotator cuff repair in patients who received either progressive exercise therapy (PR) or usual care (UC) in a randomized controlled trial and to investigate whether there was interaction with tendon retear and limb dominance.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Patients with surgically repaired traumatic full-thickness rotator cuff tears involving the supraspinatus tendon were included. After surgery, they were randomized to PR or UC (active from postoperative week 2 or 6, respectively). The subacromial structures (acromiohumeral distance, supraspinatus tendon thickness, and vascularity) and the supraspinatus muscle thickness were examined with ultrasound at the 1-year follow-up.

RESULTS

A total of 79 patients were included. The characteristics of the 2 intervention groups (PR and UC) were comparable, including the Western Ontario Rotator Cuff Index score and number of retears. The authors found significantly thinner supraspinatus tendon (PR, P < .001; UC, P = .003) and reduced acromiohumeral distance (PR, P = .023; UC, P = .025) in the repaired versus the contralateral shoulders in both intervention groups. For neovascularization, there was no interlimb difference in either of the groups or between groups (PR vs UC). In patients with intact tendons, there was no interlimb difference in the muscle thickness, but in patients with tendon retear the muscle was significantly thinner on the repaired side (P = .024 and P < .001, respectively). When the dominant supraspinatus tendon was repaired (both groups), it was significantly thinner than the nondominant healthy tendon, but this difference was not seen when the nondominant supraspinatus tendon was repaired (P = .006).

CONCLUSION

One year after rotator cuff surgery, the repaired supraspinatus tendon was significantly thinner and the corresponding acromiohumeral distance was reduced. In patients with retear, the supraspinatus muscle was significantly thinner on the repaired side and early initiation of tendon-loading exercises did not affect these findings.

REGISTRATION

NCT02969135 (ClinicalTrials.gov identifier).

Influence of Frequent Corticosteroid Local Injections on the Expression of Genes and Proteins Related to Fatty Infiltration, Muscle Atrophy, Inflammation, and Fibrosis in Patients With Chronic Rotator Cuff Tears: A Pilot Study

Background

The effect of local corticosteroid (CS) injections on rotator cuff muscles remains poorly defined, despite the significance of muscle quality as a crucial prognostic factor for patients with rotator cuff tears (RCTs).

Purpose

To compare alterations in gene and protein expression patterns in the rotator cuff muscles of patients with RCTs who received frequent joint CS injections with alterations in those without a history of CS injections.

Study Design

Controlled laboratory study.

Methods

A total of 24 rotator cuff muscle samples with medium-sized tears from 12 patients with a frequent joint CS injection history (steroid group; 7 men and 5 women who had received ≥5 injections with at least 1 within the previous 3 months; mean age, 63.0 ± 7.2 years) and 12 age- and sex-matched control patients without a history of CS injections (no-steroid group) were acquired. Alterations in the expression of genes and proteins associated with adipogenesis, myogenesis, inflammation, and muscle fibrosis were compared between the groups using quantitative reverse transcription-polymerase chain reaction, Western blotting, and immunohistochemistry. Statistical analysis included comparison of group means using the Mann-Whitney U test, chi-square test, or Fisher exact test and logistic regression for multivariate analysis.

Results

In the steroid group, the mRNA expression levels of adipogenic CCAAT/enhancer-binding protein alpha (C/EBPα; P = .008) and muscle atrophy-related genes (atrogin; P = .019) were significantly higher, and those of myogenic differentiation 1 (MyoD; P = .035), inflammatory interleukin 6 (IL-6; P = .035), and high mobility group box 1 (P = .003) were significantly lower compared with the no-steroid group. In addition, MyoD (P = .041) and IL-6 (P = .026) expression were decreased in the steroid versus no-steroid group. Immunohistochemistry revealed increased expression of C/EBPα and atrogin and decreased expression of MyoD and IL-6 in the steroid versus no-steroid group.

Conclusion

Patients with RCTs and a history of frequent CS injections exhibited an upregulation of adipogenic and muscle atrophy-related genes and proteins within the rotator cuff muscles and a downregulation in the expression of myogenic and inflammatory genes and proteins in the same muscles.

Clinical Relevance

These altered gene and protein expressions by frequent local CS injections may cause poor outcomes in patients with RCTs.

A Hybrid Electrospun-Extruded Polydioxanone Suture for Tendon Tissue Regeneration

Many surgical tendon repairs fail despite advances in surgical materials and techniques. Tendon repair failure can be partially attributed to the tendon's poor intrinsic healing capacity and the repurposing of sutures from other clinical applications. Electrospun materials show promise as a biological scaffold to support endogenous tendon repair, but their relatively low tensile strength has limited their clinical translation. It is hypothesized that combining electrospun fibers with a material with increased tensile strength may improve the suture's mechanical properties while retaining biophysical cues necessary to encourage cell-mediated repair. This article describes the production of a hybrid electrospun-extruded suture with a sheath of submicron electrospun fibers and a core of melt-extruded fibers. The porosity and tensile strength of this hybrid suture is compared with an electrospun-only braided suture and clinically used sutures Vicryl and polydioxanone (PDS). Bioactivity is assessed by measuring the adsorbed serum proteins on electrospun and melt-extruded filaments using mass spectrometry. Human hamstring tendon fibroblast attachment and proliferation were quantified and compared between the hybrid and control sutures. Combining an electrospun sheath with melt-extruded cores created a hybrid braid with increased tensile strength (70.1 ± 0.3N) compared with an electrospun only suture (12.9 ± 1 N, p < 0.0001). The hybrid suture had a similar force at break to clinical sutures, but lower stiffness and stress. The Young's modulus was 772.6 ± 32 MPa for the hybrid suture, 1693.0 ± 69 MPa for PDS, and 3838.0 ± 132 MPa for Vicryl, p < 0.0001. Hybrid sutures had lower overall porosity than electrospun-only sutures (40 ± 4% and 60 ± 7%, respectively, p = 0.0018) but had a significantly larger overall porosity and average pore diameter compared with surgical sutures. There were similar clusters of adsorbed proteins on electrospun and melt-extruded filaments, which were distinct from PDS. Tendon fibroblast attachment and cell proliferation on hybrid and electrospun sutures were significantly higher than on clinical sutures. This study demonstrated that a bioactive suture with increased tensile strength and lower stiffness could be produced by adding a core of 10 μm melt-extruded fibers to a sheath of electrospun fibers. In contrast to currently used sutures, the hybrid sutures promoted a bioactive response: serum proteins adsorbed, and fibroblasts attached, survived, grew along the sutures, and adopted appropriate morphologies.

Whole Genome Expression Profiling of Semitendinosus Tendons from Children with Diplegic and Tetraplegic Cerebral Palsy

Cerebral palsy (CP) is the most common movement disorder in children, with a prevalence ranging from 1.5 to 4 per 1000 live births. CP is caused by a non-progressive lesion of the developing brain, leading to progressive alterations of the musculoskeletal system, including spasticity, often leading to the development of fixed contractures, necessitating tendon lengthening surgery. Total RNA-sequencing analysis was performed on semitendinosus tendons from diplegic and tetraplegic CP patients subjected to tendon lengthening surgery compared to control patients undergoing anterior cruciate ligament reconstructive surgery. Tetraplegic CP patients showed increased expression of genes implicated in collagen synthesis and extracellular matrix (ECM) turnover, while only minor changes were observed in diplegic CP patients. In addition, tendons from tetraplegic CP patients showed an enrichment for upregulated genes involved in vesicle-mediated transport and downregulated genes involved in cytokine and apoptotic signaling. Overall, our results indicate increased ECM turnover with increased net synthesis of collagen in tetraplegic CP patients without activation of inflammatory and apoptotic pathways, similar to observations in athletes where ECM remodeling results in increased tendon stiffness and tensile strength. Nevertheless, the resulting increased tendon stiffness is an important issue in clinical practice, where surgery is often required to restore joint mobility.

The association of metabolic syndrome with rotator cuff tendinopathy: a two-sample Mendelian randomization study

BACKGROUND

Observational research reported the underlying correlation of metabolic syndrome (MetS) and its components with rotator cuff tendinopathy (RCT), but their causality remained unclear. This study aimed to investigate whether genetically predicted MetS was related to the risk of RCT.

METHODS

Both univariable and multivariable Mendelian randomization (MR) analysis was applied using summary-level data from the most comprehensive genome-wide association studies to estimate the associations of MetS and its component with RCT, with the inverse variance weighted (IVW) as the primary method, and the method of Causal Analysis Using Summary Effect Estimates (CAUSE) as a supplement for false positives detection. The mediation analysis was furtherly used for the assessment of direct and indirect effects.

RESULTS

Univariable analysis revealed that genetically predicted MetS (OR: 1.0793; 95% CI 1.0311 to 1.1297), body mass index (BMI) (OR 1.2239; 95% CI 1.1357 to 1.3189), and waist circumference (WAC) (OR 1.3177; 95% CI 1.2015 to 1.4451) had a significant positive association with the risk of RCT. Triglycerides and systolic blood pressure were suggestively associated with RCT risk. These associations were also identified by CAUSE. There was independent causality of BMI (OR: 1.1806; 95% CI 1.0788 to 1.2920) and WAC (OR 1.3716; 95% CI 1.2076 to 1.5580) on RCT after adjustment for confounders. No mediator was found in the causal associations.

CONCLUSION

Our study revealed the genetic causality of MetS and its components, especially BMI and WAC, with RCT risk. Early prevention and diagnosis of excess central adiposity contributing to MetS are significant in the RCT risk management.

[The use of sodium hyaluronate to treat upper limb disease: A review]

The most common diseases of the upper limb are osteoarthritis (OA) of the joints of the hands, lateral epiconlitis, tendinitis of the shoulder muscles, adhesive capsulitis. OA of the shoulder and acromioclavicular joints is less common. The development of acute and subacute pain in the elbow and shoulder joints in the vast majority of cases is determined by the pathology of soft tissues: muscles, ligamentous apparatus and related synovial bags, making it difficult to diagnose. A clinical and radiological heterogeneity of OA of the joints of the hands is a very complex pathology for the study, and also to create a unified algorithms for therapy. Therapy nonsteroidal anti-inflammatory drugs are effective in the short term, but it has several side effects. Despite a variety of attempts at therapy with successful and unsuccessful outcome, the attention of researchers for several decades converted to the injection therapy with hyaluronic acid. The article presents the data of studies demonstrating the anti-inflammatory effect of hyaluronic acid in the treatment of OA, as well as the results of clinical trials and data system of meta-analysis demonstrating the effectiveness of intra-articular and extra-articular therapy tendinopathy of the upper limb. Most of the cited studies demonstrated the efficacy and good tolerance of 1% sodium hyaluronate. In the domestic market it is presented in the drug Flexotron Forte. The authors provide the results of the study results, demonstrating the efficacy and safety of using Flexotron Forte to clinical practice.

Comparison of three common shoulder injections for rotator cuff tears: a systematic review and network meta-analysis

OBJECTIVE

To compare the clinical effectiveness of three common shoulder injections mentioned in the guidelines [corticosteroid, sodium hyaluronate (SH) and platelet-rich plasma (PRP)] on rotator cuff tears.

MATERIAL AND METHODS

The PubMed, Embase and Cochrane Library databases were systematically searched up to June 1, 2022, for randomized controlled trials (RCTs) and prospective studies on the three injection therapies for rotator cuff tears. The main results were pain relief and functional improvement at 1-5 months and over 6 months, pooled using a network meta-analysis and ranked by SUCRA score. The risk of bias of the included studies was assessed using the Cochrane Collaboration tool.

RESULTS

Twelve RCTs and 4 prospective studies comprising a total of 1115 patients were included in the review. Three prospective studies were judged to be at high risk of selection bias and performance bias, and one was considered as having a high risk of detection bias. SH injection ranked first in the short term in pain relief (MD: - 2.80; 95%CI - 3.91, - 1.68) and functional improvement (MD:19.17; 95%CI 12.29, 26.05), while PRP injection obtained better results in the long term in both pain relief (MD: - 4.50; 95%CI - 4.97, - 4.03) and functional improvement (MD:11.11; 95%CI 0.53,21.68).

CONCLUSIONS

PRP injection has the potential to successfully treat rotator cuff tears as an alternative to corticosteroids in the long term, in terms of either therapeutic efficiency or adverse effects, followed by SH injection. More research is needed to make high-quality recommendations on treatment options for injection treatments of rotator cuff tears.

Are the Pathologic Features of Enthesopathy, Tendinopathy, and Labral and Articular Disc Disease Related to Mucoid Degeneration? A Systematic Review

BACKGROUND

Tendinopathy, enthesopathy, labral degeneration, and pathologic conditions of the articular disc (knee meniscus and ulnocarpal) are sometimes described in terms of inflammation or damage, while the histopathologic findings are often consistent with mucoid degeneration. A systematic review of the histopathology of these structures at diverse locations might reconceptualize these diseases as expected aspects of human aging. The potential benefits of this evolution might include healthier patient and clinician mindsets as well as a reduced likelihood of overdiagnosis and overtreatment resulting from greater awareness of base rates of pathology.

QUESTION/PURPOSE

In this systematic review of studies of surgical specimens, we asked: Are there are any differences in the histopathologic findings of structural soft tissue conditions (mucoid degeneration, inflammation, and vascularity) by anatomic site (foot, elbow, or knee) or structure (tendon body, muscle or tendon origin or insertion [enthesis], labrum, or articular disc)?

METHODS

Studies between 1980 and 2021 investigating the histopathologic findings of specimens from surgery for trigger digit, de Quervain tendinopathy, plantar fasciitis, lateral and medial elbow enthesopathy, rotator cuff tendinopathy, posterior tibial tendinopathy, patellar tendinopathy, Achilles tendinopathy, or disease of the hip labrum, ulnocarpal articular disc, or knee meniscus were searched for in the PubMed, EMBASE, and CINAHL databases. Inclusion criteria were the prespecified anatomic location or structure being analyzed histologically and any findings described with respect to inflammation, vascularity, or mucoid degeneration. Studies were excluded if they were nonhuman studies or review articles. Search terms included "anatomy," "pathology," and "histopathology." These terms were coupled with anatomic structures or disorders and included "trigger finger," "de Quervain," "fasciitis, plantar," "tennis elbow," "rotator cuff tendinopathy," "elbow tendinopathy," "patellar tendonitis," "posterior tibial tendon," and "triangular fibrocartilage." This resulted in 3196 studies. After applying the inclusion criteria, 559 articles were then assessed for eligibility according to our exclusion criteria, with 52 eventually included. We recorded whether the study identified the following histopathologic findings: inflammatory cells or molecular markers, greater than expected vascularity (categorized as quantitative count, with or without controls; molecular markers; or qualitative judgments), and features of mucoid degeneration (disorganized collagen, increased extracellular matrix, or chondroid metaplasia). In the absence of methods for systematically evaluating the pathophysiology of structural (collagenous) soft tissue structures and rating histopathologic study quality, all studies that interpreted histopathology results were included. The original authors' judgment regarding the presence or absence of inflammation, greater than expected vascularity, and elements of mucoid degeneration was recorded along with the type of data used to reach that conclusion.

RESULTS

Regarding differences in the histopathology of surgical specimens of structural soft tissue conditions by anatomic site, there were no differences in inflammation or mucoid degeneration, and the knee meniscus was less often described as having greater than normal vascularity. There were no differences by anatomic structure. Overall, 20% (10 of 51) of the studies that investigated for inflammation reported it (nine inflammatory cells and one inflammatory marker). Eighty-three percent (43 of 52) interpreted increased vascularity: 40% (17 of 43) using quantitative methods (14 with controls and three without) and 60% (26 of 43) using imprecise criteria. Additionally, 100% (all 52 studies) identified at least one element of mucoid degeneration: 69% (36 of 52) reported an increased extracellular matrix, 71% (37 of 52) reported disorganized collagen, and 33% (17 of 52) reported chondroid metaplasia.

CONCLUSION

Our systematic review of the histopathology of diseases of soft tissue structures (enthesopathy, tendinopathy, and labral and articular disc) identified consistent mucoid degeneration, minimal inflammation, and imprecise assessment of relative vascularity; these findings were consistent across anatomic sites and structures, supporting a reconceptualization of these diseases as related to aging (senescence or degeneration) rather than injury or activity.

CLINICAL RELEVANCE

This reconceptualization supports accommodative mindsets known to be associated with greater comfort and capability. In addition, awareness of the notable base rates of structural soft tissue changes as people age might reduce overdiagnosis and overtreatment of incidental, benign, or inconsequential signal changes and pathophysiology.

Risk factors for rotator cuff disease: A systematic review and meta-analysis of diabetes, hypertension, and hyperlipidemia

BACKGROUND

Rotator cuff disease is a common cause of shoulder pain. Comorbidities such as diabetes, hypertension, and hyperlipidemia may be associated with rotator cuff disease, likely because of mechanisms related to vascular insufficiency.

OBJECTIVES

We performed a systematic review of the association of diabetes, hypertension, and hyperlipidemia with the diagnosis of rotator cuff disease.

METHODS

Following systematic queries of PubMed, Embase, Cochrane, CINAHL, and Science Direct, articles meeting eligibility criteria and reporting on the association of one or more risk factors (diabetes, hypertension, and hyperlipidemia) and rotator cuff disease were considered. Meta-analysis was performed to quantitatively summarize the associations between each risk factor and rotator cuff disease. We assessed study quality with the Newcastle-Ottawa Scale (NOS) and performed a qualitative assessment of risk of bias.

RESULTS

After a full-text review of 212 articles, 12 articles assessing diabetes, 5 assessing hypertension and 8 assessing hyperlipidemia were eligible. The odds of having rotator cuff disease was increased with diabetes (odds ratio [OR] 1.49, 95% confidence interval [CI] 1.43-1.55), hypertension (OR 1.40, 95% CI 1.19-1.65) and hyperlipidemia/dyslipidemia (OR 1.48, 95% CI 1.42-1.55). Diabetes was also specifically associated with rotator cuff tears (OR 1.28, 95% CI 1.07-1.52). Synthesizing assessment for risk of bias suggested that current epidemiologic evidence for an association was plausible for diabetes and hyperlipidemia but not hypertension.

CONCLUSIONS

Diabetes, hypertension, and hyperlipidemia were associated with rotator cuff disease in our meta-analysis. However, the possibility of bias exists for all 3 co-morbidities evaluated and is likely highest for hypertension. High-quality studies with the ability to incorporate time since first diagnosis of co-morbidity are scarce and much needed.

"You have (rotator cuff related) shoulder pain, and to treat it, I recommend exercise." A scoping review of the possible mechanisms underpinning exercise therapy

BACKGROUND

Exercise is considered to be both essential and at the forefront of the management of rotator cuff-related shoulder pain (RCRSP). Despite this, many fail to substantially improve with exercise-based treatment. Hence, expanding the current knowledge about the possible mechanisms of exercise for RCRSP is critical.

OBJECTIVE

To synthesise the range of mechanisms proposed for exercise in people with RCRSP.

DESIGN

Scoping review METHODS: A systematic search of the Physiotherapy Evidence Database (PEDro) was conducted from inception to July 3, 2022. Two reviewers conducted the search and screening process and one reviewer extracted the data from each study. Randomised clinical trials using exercise for the management of RCRSP of any duration were included. The PEDro search terms used were "fitness training", "strength training", "stretching, mobilisation, manipulation, massage", "upper arm, shoulder, or shoulder girdle", "pain", and "musculoskeletal". Data were analysed using quantitative and qualitative approaches.

RESULTS

626 studies were identified and 110 were included in the review. Thirty-two unique mechanisms of exercise were suggested by clinical trialists, from which 4 themes emerged: 1) neuromuscular 2) tissue factors 3) neuro-endocrine-immune 4) psychological. Neuromuscular mechanisms were proposed most often (n = 156, 77%). Overall, biomedical mechanisms of exercise were proposed in 95% of cases.

CONCLUSIONS

The causal explanation for the beneficial effect of exercise for RCRSP in clinical research is dominated by biomedical mechanisms, despite a lack of supporting evidence. Future research should consider testing the mechanisms identified in this review using mediation analysis to progress knowledge on how exercise might work for RCRSP.

Biomolecules Related to Rotator Cuff Pain: A Scoping Review

The pathophysiology of pain in patients suffering from rotator cuff (RC) tendinopathy or tears has been examined in various ways. Several molecules from tissue samples taken from the subacromial bursa, supraspinatus tendon, glenohumeral joint fluid, and synovium as well as from peripheral blood have been investigated. This article explores these studies, the assessed biomarkers, and groups their results according to the status of tendon integrity (tendinopathy or tear). Through a structured PubMed database search, 9 out of 658 articles were reviewed. Interleukins, mostly IL-1b and its antagonist, IL-1ra, matrix Metalloproteinases (MMPs), the vascular endothelial growth factor (VEGF) and TNF-a are biomarkers directly searched for correlation to pain level. Most studies agree that IL-1b is directly positively correlated to the degree of pain in patients with RC tendinopathy, especially when the examined sample is taken from the subacromial bursa. VEGF, and TNF-a have been related to shoulder pain preoperatively and TNF-a has also been linked with sleep disturbance. Further studies pointing to more biomarkers taken from the subacromial bursa or tendon directly relating to pain degree are warranted.

Corticosteroid Injections After Rotator Cuff Repair Improve Function, Reduce Pain, and Are Safe: A Systematic Review

Purpose

To review the literature on postoperative corticosteroid injections (CSIs) following primary rotator cuff repair (RCR) to evaluate efficacy and adverse effects.

Methods

A systematic review of the MEDLINE, EMBASE, and Cochrane databases were performed to identify all studies published within the last 15 years, which reported on outcomes of postoperative CSIs following RCR. Studies including patients who received only preoperative CSIs and revision RCRs were excluded. Included studies were evaluated for study methodology, patient demographics, outcome measures, physical examination parameters, results of imaging studies, and adverse effects or clinical complications.

Results

Seven studies comprising 5,528 patients satisfied inclusion criteria. Among included patients, 54.8% were female and mean age range from 52.3 ± 13.0 to 62.7 ± 6.6 years. Only 1 included investigation was a Level I study. Overall, 4 of 5 studies reported significant improvements in pain and outcome scores (Constant score, American Shoulder and Elbow Surgeons score) compared with controls. Across all studies, the majority of these effects were statistically significant at 3 months postoperatively but not beyond this time point. Five of the 6 included investigations reported no increased rate of retears after postoperative CSIs. One study did find an increase in retear in patients receiving postoperative CSIs but was unable to determine whether these retears were present before the patient received the CSI. Another investigation reported an increased rate of infection only if the CSI was administered in the first postoperative month.

Conclusions

Postoperative CSIs may improve pain and function for up to 3 months following primary RCR but not at later follow-up time points. CSIs should be administered only after the first postoperative month to minimize the potential risk for adverse events.

Level of Evidence

Systematic review of level I-IV studies.

The Usefulness of Serological Inflammatory Markers in Patients with Rotator Cuff Disease-A Systematic Review

Background and Objectives: Rotator cuff disease (RCD) is a prominent musculoskeletal pain condition that spans a variety of pathologies. The etiology and precise diagnostic criteria of this condition remain unclear. The current practice of investigating the biochemical status of RCD is by conducting biopsy studies but their invasiveness is a major limitation. Recent biochemical studies on RCD demonstrate the potential application of serological tests for evaluating the disease which may benefit future clinical applications and research. This systematic review is to summarize the results of available studies on serological biochemical investigations in patients with RCD. Methods: An electronic search on databases PubMed and Virtual Health Library was conducted from inception to 1 September 2021. The inclusion criteria were case-control, cross-sectional, and cohort studies with serological biochemical investigations on humans with RCD. Methodological quality was assessed using the Study Quality Assessment Tool for Observational Cohort and Cross-sectional studies from the National Heart, Lung, and Blood Institute. Results: A total of 6008 records were found in the databases; of these, 163 full-text studies were checked for inclusion and exclusion criteria. Nine eligible studies involving 984 subjects with RCD emerged from this systematic review. The quality of the studies found ranged from poor to moderate. In summarizing all the studies, several fatty acids, nonprotein nitrogen, interleukin-1 β, interleukin-8, and vascular endothelial growth factor were found to be significantly higher in blood samples of patients with RCD than with control group patients, while Omega-3 Intex, vitamin B12, vitamin D, phosphorus, interleukin-10, and angiogenin were observed to be significantly lower. Conclusions: This is the first systematic review to summarize current serological studies in patients with RCD. Results of the studies reflect several systemic physiological changes in patients with RCD, which may prove helpful to better understand the complex pathology of RCD. In addition, the results also indicate the possibility of using serological tests in order to evaluate RCD; however, further longitudinal studies are required.

The Impact of Hyaluronic Acid on Tendon Physiology and Its Clinical Application in Tendinopathies

The physical-chemical, structural, hydrodynamic, and biological properties of hyaluronic acid within tendons are still poorly investigated. Medical history and clinical applications of hyaluronic acid for tendinopathies are still debated. In general, the properties of hyaluronic acid depend on several factors including molecular weight. Several preclinical and clinical experiences show a good efficacy and safety profile of hyaluronic acid, despite the absence of consensus in the literature regarding the classification according to molecular weight. In in vitro and preclinical studies, hyaluronic acid has shown physical-chemical properties, such as biocompatibility, mucoadhesivity, hygroscopicity, and viscoelasticity, useful to contribute to tendon healing. Additionally, in clinical studies, hyaluronic acid has been used with promising results in different tendinopathies. In this narrative review, findings encourage the clinical application of HA in tendinopathies such as rotator cuff, epicondylitis, Achilles, and patellar tendinopathy.

Tendon midsubstance trauma as a means for the development of translatable chronic rotator cuff degeneration in an ovine model

BACKGROUND

Chronic degeneration of rotator cuff tendons is a major contributing factor to the unacceptably high prevalence of rotator cuff repair surgery failures. The etiology of chronic rotator cuff degeneration is not well understood, and current therapies are not effective, necessitating preclinical research to fill this knowledge gap. Unfortunately, current large animal models rely on enthesis disruption as a means of model generation, which is not representative of human patients with chronic rotator cuff degeneration prior to full-thickness tears. Following, the goal of this study was to develop and characterize a translational large-animal model of chronic rotator cuff degeneration without enthesis release.

METHODS

A midsubstance damage model [i.e., "combed fenestration" (CF)] in adult sheep was generated by creating 16 longitudinal cuts within the top third of the infraspinatus tendon thickness. Tendon integrity was characterized through exhaustive non-destructive biomechanical stress relaxation testing [peak stress, peak load, percent relaxation, and cross-sectional area (CSA)], followed by histopathological degeneration scoring and analysis (Bonar score), histomorphological analysis of collagen organization and fatty atrophy (percent adipose area), and gene expression analyses.

RESULTS

The CF model tendons exhibited significantly decreased mechanical properties as evidenced by decreased peak stress (P<0.025) and increased percent relaxation (18-week vs. Control, P<0.035) at multiple strain magnitudes and across all timepoints. At all timepoints, the CF tendons exhibited pathological changes aligned with tendon degeneration, as evidenced by increased Bonar scoring (P<0.001) and decreased collagen organization (6-week vs. Control, P=0.013). Increases in intramuscular adipose content were also documented through histomorphology analysis (6- and 18-week vs. Control, P<0.077). Significant changes in gene expression were noted at all timepoints.

CONCLUSIONS

These data reveal that this new ovine CF model of chronic rotator cuff degeneration results in tendons with decreased mechanical properties, degenerative pathology characteristics, and gene expression profiles that aligned with the degenerative changes that have been noted in humans with tendinopathy. For these reasons, we believe this novel large animal model of chronic rotator cuff degeneration is a translational platform in which to test devices, therapies, and/or technologies aimed at repairing damage to the shoulder.

Effectiveness of Adding a Large Dose of Shoulder Strengthening to Current Nonoperative Care for Subacromial Impingement: A Pragmatic, Double-Blind Randomized Controlled Trial (SExSI Trial)

BACKGROUND

A strong recommendation against subacromial decompression surgery was issued in 2019. This leaves nonoperative care as the only treatment option, but recent studies suggest that the dose of strengthening exercise is not sufficient in current nonoperative care. At this point, it is unknown if adding more strengthening to current nonoperative care is of clinical value.

PURPOSE

To assess the effectiveness of adding a large dose of shoulder strengthening to current nonoperative care for subacromial impingement compared with usual care alone.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

In this double-blinded, pragmatic randomized controlled trial, we randomly allocated 200 consecutive patients referred to orthopaedic shoulder specialist care for long-standing shoulder pain (>3 months), aged 18 to 65 years and diagnosed with subacromial impingement using validated criteria, to the intervention group (IG) or control group (CG). Outcome assessors were blinded, and participants were blinded to the study hypothesis as well as to the treatment method in the other group. The CG received usual nonoperative care; the IG underwent the same plus an add-on intervention designed to at least double the total dose of shoulder strengthening. The primary outcome was the Shoulder Pain and Disability Index (SPADI; 0-100) at 4-month follow-up, with 10 points defined as the minimal clinically important difference. Secondary outcomes included shoulder strength, range of motion, health-related quality of life, and the Patient Acceptable Symptom State (PASS).

RESULTS

Intention-to-treat and per-protocol analyses showed no significant or clinically relevant between-group differences for any outcome. From baseline to 4-month follow-up, SPADI scores improved in both groups (intention-to-treat analysis; IG, -22.1 points; CG, -22.7 points; between-group mean difference, 0.6 points [95% CI, -5.5 to 6.6]). At 4 months after randomization, only 54% of the IG and 48% of the CG (P = .4127) reached the PASS. No serious adverse events were reported.

CONCLUSION

Adding a large dose of shoulder strengthening to current nonoperative care for patients with subacromial impingement did not result in superior shoulder-specific patient-reported outcomes. Moreover, approximately half of all randomized patients did not achieve the PASS after 4 months of nonoperative care, leaving many of these patients with unacceptable symptoms. This study showed that adding more exercise is not a viable solution to this problem.

REGISTRATION

NCT02747251 (ClinicalTrials.gov identifier).

Rotator cuff assessment on imaging

The rotator cuff is a group of four muscles and tendons surrounding the shoulder joint providing it strength and stability. The rotator cuff consists of the subscapularis, supraspinatus, infraspinatus and teres minor. Many shoulder complaints are caused by rotator cuff pathology such as impingement syndrome, tendon tears and other diseases e.g. calcific tendonitis. Diagnosis starts with clinical history and physical examination, after which imaging is often used to help confirm clinical findings depending on the differential diagnosis. The aim of the article is to review the frequently used imaging modalities to assess the rotator cuff and cuff-related disease, specifically focusing on radiography, ultrasonography and magnetic resonance imaging. This article will outline the advantages and disadvantages for each modality and illustrate typical radiological findings of common rotator cuff pathologies.

The interaction between human rotator cuff tendon and subacromial bursal tissue in co-culture

BACKGROUND

The role of subacromial bursa in rotator cuff pathology is unclear. Along with recognized inflammatory potential, current data demonstrate the presence of mesenchymal stem cells and potential regenerative properties of the bursa. The purpose of this study was to (1) approximate an in vitro co-culture model that represents interaction between torn rotator cuff tendon and subacromial bursa, (2) quantify the cellular activity of tendon and bursa and their interactions, (3) use this model to induce a state of inflammation present with rotator cuff pathology.

METHODS

In part 1, tendon and bursa samples were obtained from 6 patients undergoing rotator cuff repair. Tendon and bursa were cultured alone and together in co-culture wells for 21 days. Markers specific for tenocyte gene expression (tenascin C, decorin, etc) were measured in both tendon and bursa alone and compared to co-culture models. In part 2 of the study, an inflammatory state was induced with interleukin-1β treatment, and markers of inflammation were measured via protein assay at 0 and 21 days in samples from 7 additional patients.

RESULTS

There was an increase in tendon and bursa markers in nearly all groups as evidenced by increased gene expression of known tendon and bursa markers. There was a significant increase in gene expression when torn tendon was co-cultured with bursa compared with culturing alone. Additionally, a state of inflammation was induced as evidenced by increased markers of inflammation, inflammatory protein concentration, and inflammatory cells and disruption of histologic morphology.

CONCLUSION

There is a clear interaction between rotator cuff tendon and the milieu produced by the subacromial bursa in this in vitro co-culture system that is significantly different when compared to an isolated culture of tendon and bursa. This system was successfully used to induce a state of inflammation that may represent in vivo inflammation. This in vitro model of rotator cuff pathology can aid investigators in testing effects of agents proposed to improve rotator cuff healing. This can lead to further knowledge regarding effective treatment options.

Regulatory VCAN polymorphism is associated with shoulder pain and disability in breast cancer survivors

Background and purpose

Shoulder morbidity following breast cancer treatment is multifactorial. Despite several treatment- and patient-related factors being implicated, unexplained inter-individual variability exists in the development of such morbidity. Given the paucity of relavant genetic studies, we investigate the role of polymorphisms in candidate proteoglycan genes.

Patients and methods

We conducted a cross-sectional study on 254 South African breast cancer survivors, to evaluate associations between shoulder pain/disability and ten single nucleotide polymorphisms (SNPs) within four proteoglycan genes: ACAN (rs1126823 G>A, rs1516797 G>T, rs2882676 A>C); BGN (rs1042103 G>A, rs743641 A>T, rs743642 G>T); DCN rs516115 C>T; and VCAN (rs11726 A>G, rs2287926 G>A, rs309559). Participants were grouped into no–low and moderate–high shoulder pain/disability based on total pain/disability scores: < 30 and ≥ 30, respectively using the Shoulder Pain and Disability Index (SPADI).

Results

The GG genotype of VCAN rs11726 was independently associated with an increased risk of being in the moderate-to-high shoulder pain (P = 0.005, OR = 2.326, 95% CI = 1.259–4.348) or disability (P = 0.011, OR = 2.439, 95% CI = 1.235–4.762) categories, after adjusting for participants’ age. In addition, the T-T-G inferred allele combination of BGN (rs74364–rs743642)–VCAN rs11726 was associated with an increased risk of being in the moderate-to-high shoulder disability category (0 = 0.002, OR = 2.347, 95% CI = 1.215–4.534).

Conclusion

Our study is first to report that VCAN rs11726, independently or interacting with BGN polymorphisms, is associated with shoulder pain or disability in breast cancer survivors. Whereas our findings suggest an involvement of proteoglycans in the etiology of shoulder pain/disability, further studies are recommended.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40246-021-00337-0.

Comparison of Cellular Responses to TGF-β1 and BMP-2 Between Healthy and Torn Tendons

BACKGROUND

Tendons heal by fibrotic repair, increasing the likelihood of reinjury. Animal tendon injury and overuse models have identified transforming growth factor beta (TGF-β) and bone morphogenetic proteins (BMPs) as growth factors actively involved in the development of fibrosis, by mediating extracellular matrix synthesis and cell differentiation.

PURPOSE

To understand how TGF-β and BMPs contribute to fibrotic processes using tendon-derived cells isolated from healthy and diseased human tendons.

STUDY DESIGN

Controlled laboratory study.

METHODS

Tendon-derived cells were isolated from patients with a chronic rotator cuff tendon tear (large to massive, diseased) and healthy hamstring tendons of patients undergoing anterior cruciate ligament repair. Isolated cells were incubated with TGF-β1 (10 ng/mL) or BMP-2 (100 ng/mL) for 3 days. Gene expression was measured by real-time quantitative polymerase chain reaction. Cell signaling pathway activation was determined by Western blotting.

RESULTS

TGF-β1 treatment induced ACAN mRNA expression in both cell types but less in the diseased compared with healthy cells (P < .05). BMP-2 treatment induced BGN mRNA expression in healthy but not diseased cells (P < .01). In the diseased cells, TGF-β1 treatment induced increased ACTA2 mRNA expression (P < .01) and increased small mothers against decapentaplegic (SMAD) signaling (P < .05) compared with those of healthy cells. Moreover, BMP-2 treatment induced ACTA2 mRNA expression in the diseased cells only (P < .05).

CONCLUSION

Diseased tendon-derived cells show reduced expression of the proteoglycans aggrecan and biglycan in response to TGF-β1 and BMP-2 treatments. These same treatments induced enhanced fibrotic differentiation and canonical SMAD cell signaling in diseased compared with healthy cells.

CLINICAL RELEVANCE

Findings from this study suggest that diseased tendon-derived cells respond differently than healthy cells in the presence of TGF-β1 and BMP-2. The altered responses of diseased cells may influence fibrotic repair processes during tendon healing.

Electrospun Scaffold Micro-Architecture Induces an Activated Transcriptional Phenotype within Tendon Fibroblasts

Biomaterial augmentation of surgically repaired rotator cuff tendon tears aims to improve the high failure rates (∼40%) of traditional repairs. Biomaterials that can alter cellular phenotypes through the provision of microscale topographical cues are now under development. We aimed to systematically evaluate the effect of topographic architecture on the cellular phenotype of fibroblasts from healthy and diseased tendons. Electrospun polydioxanone scaffolds with fiber diameters ranging from 300 to 4000 nm, in either a highly aligned or random configuration, were produced. Healthy tendon fibroblasts cultured for 7 days on scaffolds with highly aligned fibers demonstrated a distinctive elongated morphology, whilst those cultured on randomly configured fibers demonstrated a flattened and spread morphology. The effect of scaffold micro-architecture on the transcriptome of both healthy and diseased tendon fibroblasts was assessed with bulk RNA-seq. Both healthy (n = 3) and diseased tendon cells (n = 3) demonstrated a similar transcriptional response to architectural variants. Gene set enrichment analysis revealed that large diameter (≥2000 nm) aligned scaffolds induced an upregulation of genes involved in cellular replication and a downregulation of genes defining inflammatory responses and cell adhesion. Similarly, PDPN and CD248, markers of inflammatory or "activated" fibroblasts, were downregulated during culture of both healthy and diseased fibroblasts on aligned scaffolds with large (≥2000 nm) fiber diameters. In conclusion scaffold architectures resembling that of disordered type III collagen, typically present during the earlier phases of wound healing, resulted in tendon fibroblast activation. Conversely, scaffolds mimicking aligned diameter collagen I fibrils, present during tissue remodelling, did not activate tendon derived fibroblasts. This has implications for the design of scaffolds used during rotator cuff repair augmentation.

Could superior capsule findings be used as a predictor for partial bursal-sided rotator cuff tears?

PURPOSE

The purpose of this study was to investigate the relationship between the superior capsule tear patterns and synovitis with subacromial pathologies, such as bursal-sided rotator cuff tear and subacromial impingement syndrome.

METHODS

Fifty patients who underwent arthroscopic treatment for isolated bursal-sided tear were included in the study. Fifty more patients who underwent arthroscopic treatment for isolated Superior Labrum Anterior Posterior (SLAP) 2 lesion without pathology in the rotator cuff were included in the control group. Firstly, superior capsule tear and common synovitis on the rotator cable were assessed during glenohumeral joint examination. Coracoacromial Ligament (CAL) degeneration grading was performed according to the Royal Berkshire Hospital classification. Bursal-sided partial tear grading was done using Ellman classification. Whether or not there was a relationship between synovitis, classic capsule tear, plus reverse flap capsule tear, and partial bursal-sided tear existence.

RESULTS

There were 21 patients with reverse flap capsule tear in the study group and 3 patients in the control group. In addition, there were 13 patients with synovitis in the study group and 4 in the control group. Compared to the control group, there was also a significant positive correlation in the presence of both synovitis and reverse flap capsule tear with the presence of bursal-sided tear in the study group (p = 0.000). There was, however, no significant difference between the presence of classical capsule tear and the presence of bursal-sided tear (p = 0.485).

CONCLUSION

This study shows that the presence of reverse flap capsule tear and synovitis was associated with partial bursal-sided tears. Therefore, if the reverse flap capsule tear or synovitis is detected in the superior capsule, the rotator cuff should be evaluated in more detail during subacromial bursoscopy in order not to miss a bursal-sided partial cuff tear.

Adverse Impact of Corticosteroid Injection on Rotator Cuff Tendon Health and Repair: A Systematic Review

PURPOSE

To assess adverse effects of preoperative corticosteroid injections (CSIs) in patients with rotator cuff disease, especially before rotator cuff repair (RCR).

METHODS

A systematic review of the MEDLINE database was performed according to guidelines from the Preferred Reporting Item for Systematic Reviews and Meta-Analyses for all studies reporting on adverse clinical effects of CSIs on rotator cuff tendon.

RESULTS

A total of 8 articles were identified that report on adverse outcomes and risks associated with corticosteroid injections in the setting of rotator cuff tendinosis. Among these included articles, a single CSI for rotator cuff tendinosis was associated with increased risk of revision rotator cuff repair (odds ratio [OR]: range 1.3 [1.1-1.7] to 2.8 [2.2-3.4]) when administered up to a year before surgery and postoperative infections (OR: 2.1 [1.5-2.7]) when administered within a month before RCR. The risk of adverse outcomes after rotator cuff repair are greatest if a CSI is administered within 6 months of surgery (OR: 1.8 [1.3-2.6]) or if ≥2 injections are given within a year of surgery (OR: range 2.1 [1.8-2.5] to 3.3 [2.7-4.0]).

CONCLUSION

Several recent clinical trials have demonstrated that CSIs are correlated with increased risk of revision surgery after RCR in a temporal and dose dependent matter. Caution should be taken when deciding to inject a patient, and this treatment should be withheld if an RCR is to be performed within the following 6 months.

LEVEL OF EVIDENCE

IV, systematic review of Level III and IV studies.

Adverse Impact of Corticosteroids on Rotator Cuff Tendon Health and Repair: A Systematic Review of Basic Science Studies

Purpose

To evaluate the in vitro effects of corticosteroid injections (CSIs) on rotator cuff tendon (RCT).

Methods

A systematic review of the MEDLINE database was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for all studies reporting on adverse biochemical and biomechanical effects of CSIs on RCT.

Results

Sixteen studies were identified that had been published in the last 15 years on the effects of corticosteroids on RCTs. Eight of these studies were on human RCTs, 6 were on rat tendons, 1 considered both human and rat tendons, and 1 was on dog tendon. Five studies analyzed the effects of corticosteroids on the biomechanical properties of RCT or rotator cuff repair, whereas the remaining observed the cellular and molecular effects of CSIs on RCT. Corticosteroids suppress an inflammatory response, induce apoptosis, and have negative effects on collagen and tendon cell viability in RCTs. The mechanical properties, including load to failure of RCTs and rotator cuff repair anchor pull-out strength, also are decreased by CSIs. These in vitro effects appear to be transient as well as frequency and dose dependent.

Conclusions

On a molecular level, CSIs decrease cellular proliferation, alter collagen and extracellular matrix composition, impede inflammatory pathways, decrease cellular viability, increase adipocyte differentiation, and increase apoptosis. These changes can be seen as early as 24 hours after corticosteroid exposure, last as long as 2 to 3 weeks, and are exacerbated by increased doses and decreased latency between doses. Biomechanical studies demonstrate that these changes result in decreased maximal load to failure, tendon stiffness, and suture anchor pull-out strength in rat shoulders up to 2 weeks but not at 3 and 4 weeks, post-CSI.

Clinical Relevance

Shoulder subacromial steroid injection is common, and practitioners should be aware of results both positive and deleterious.

Tendon and ligament mechanical loading in the pathogenesis of inflammatory arthritis

Mechanical loading is an important factor in musculoskeletal health and disease. Tendons and ligaments require physiological levels of mechanical loading to develop and maintain their tissue architecture, a process that is achieved at the cellular level through mechanotransduction-mediated fine tuning of the extracellular matrix by tendon and ligament stromal cells. Pathological levels of force represent a biological (mechanical) stress that elicits an immune system-mediated tissue repair pathway in tendons and ligaments. The biomechanics and mechanobiology of tendons and ligaments form the basis for understanding how such tissues sense and respond to mechanical force, and the anatomical extent of several mechanical stress-related disorders in tendons and ligaments overlaps with that of chronic inflammatory arthritis in joints. The role of mechanical stress in 'overuse' injuries, such as tendinopathy, has long been known, but mechanical stress is now also emerging as a possible trigger for some forms of chronic inflammatory arthritis, including spondyloarthritis and rheumatoid arthritis. Thus, seemingly diverse diseases of the musculoskeletal system might have similar mechanisms of immunopathogenesis owing to conserved responses to mechanical stress.

Metabolic and inflammatory links to rotator cuff tear in hand osteoarthritis: A cross sectional study

Objectives

To estimate the prevalence and associated factors of rotator cuff tear (RCT) in patients with hand osteoarthritis (HOA).

Methods

Between June 2013 and December 2015, we recruited 1150 participants in rural area of South Korea. Of the 1150 participants, 307 participants with HOA were analyzed. Plain radiography of both hands, magnetic resonance imaging of both shoulders, and serum levels of high-sensitive C-reactive protein (hsCRP) and high-density lipoprotein (HDL) were obtained for all patients. HOA and RCT were diagnosed by clinical and radiologic findings.

Results

The prevalence of RCT in patients with HOA (192/307, 62.5%) was higher than that in those without HOA (410/827, 49.5%, p<0.001). Among the 307 patients with HOA, the patients with RCT were older, and had higher hsCRP and lower HDL levels than the patients without RCT. Multiple logistic regression analysis confirmed significant associations of age (odds ratio [OR], 1.06; 95% confidence interval [CI], 1.02–1.11), serum hsCRP levels ≥0.6mg/L (OR, 1.68; CI, 1.00–2.80), and low HDL levels (male, <50 mg/dL; female, <40 mg/dL) (OR, 1.93; CI, 1.05–3.56) with RCT in patients with HOA. For patients below 60 years old, the prevalence of RCT was 2.8-fold higher in the low HDL group than normal HDL group (p = 0.048). Finally, the prevalence of RCT was 2.6-fold higher in patients with HOA with both elevated hsCRP and low HDL levels compared with those with neither (p<0.05).

Conclusions

Our findings suggest inflammation and metabolic factors were associated with the prevalence of RCT in HOA patients.

ERK1/2 drives IL-1β-induced expression of TGF-β1 and BMP-2 in torn tendons

Diseased and injured tendons develop fibrosis, driven by factors including TGF-β, BMPs and CTGF. IL-1β and its signal transducer Erk1/2 are known to regulate TGF-β expression in animal tendons. We utilised tissues and cells isolated from patients with shoulder tendon tears and tendons of healthy volunteers to advance understanding of how inflammation induces fibrosis in diseased human tendons. ERK1/2 expression was reduced in torn (diseased) compared to healthy patient tendon tissues. We next investigated the fibrotic responses of tendon-derived cells isolated from healthy and diseased human tendon tissues in an inflammatory milieu. IL-1β treatment induced profound ERK1/2 signalling, TGFB1 and BMP2 mRNA expression in diseased compared to healthy tendon-derived cells. In the diseased cells, the ERK1/2 inhibitor (PD98059) completely blocked the IL-1β-induced TGFB1 and partially reduced BMP2 mRNA expression. Conversely, the same treatment of healthy cells did not modulate IL-1β-induced TGFB1 or BMP2 mRNA expression. ERK1/2 inhibition did not attenuate IL-1β-induced CTGF mRNA expression in healthy or diseased tendon cells. These findings highlight differences between ERK1/2 signalling pathway activation and expression of TGF-β1 and BMP-2 between healthy and diseased tendon tissues and cells, advancing understanding of inflammation induced fibrosis during the development of human tendon disease and subsequent repair.

Is there an association between metabolic syndrome and rotator cuff-related shoulder pain? A systematic review

Objectives

Rotator cuff-related shoulder pain (RCRSP) is a common upper limb complaint. It has been suggested that this condition is more common among people with cardiometabolic risk factors. This systematic review has synthesised evidence from case–control, cross-sectional and cohort studies on the association between metabolic syndrome (MetS) and RCRSP.

Design and data sources

Five medical databases (MEDLINE, EMBASE, SCOPUS, CINAHL and AMED) and reference checking methods were used to identify all relevant English articles that considered MetS and RCRSP. Studies were appraised using the Newcastle-Ottawa Scale (NOS). Two reviewers performed critical appraisal and data extraction. Narrative synthesis was performed via content analysis of statistically significant associations.

Results

Three cross-sectional, two case–control and one cohort study met the inclusion criteria, providing a total of 1187 individuals with RCRSP. Heterogeneity in methodology and RCRSP or MetS definition precluded a meaningful meta-analysis. Four of the included studies identified associations between the prevalence of MetS and RCRSP. Studies consistently identified independent cardiometabolic risk factors associated with RCRSP. All studies were level III evidence.

Summary and conclusion

The low-moderate quality evidence included in this review suggests an association between MetS and RCRSP. Most studies demonstrated moderate quality on appraisal. The direction of association and cardiometabolic factors influencing should be investigated by longitudinal and treatment studies. These preliminary conclusions and clinical utility should be treated with caution due to limitations of the evidence base.

Molecular profile of ultrastructure changes of the ligamentum flavum related to lumbar spinal canal stenosis

Lumbar spinal canal stenosis (LSCS) is a degenerative disease observed by hypertrophy of the ligamentum flavum (LF) that cause compression of the lumbar neural content. Diabetes mellitus (DM) is a risk factor for the disease and we have shown previously that DM increases the fibrosis and elastic fiber loss in patients with LSCS. The purpose of this study was to find the proteins that play a role in the development of this clinical pathogenesis and the effect of DM on protein expression. LF tissue retrieved from patients diagnosed with LSCS, some were also diagnosed with DM, were compared with LF from patients diagnosed with herniated nucleus pulposus (HNP). The tissues were analyzed by mass spectrometry for proteins profile alteration. We found that LF of LSCS/DM patients exhibited significantly higher levels of proteoglycan proteins and latent transforming growth factor β-binding protein (LTBP2 and LTBP4). Additionally, an increase of HTRA serine protease 1 and insulin-like growth factor binding protein-5 were noted. The higher fibrosis was also associated with proteins related to inflammation and slower tissue repair. Collagen 6 and transforming growth factor inhibitor are related to activation of the anti-inflammatory M2 pathway that is associated with tissue repair. The decrease of these proteins expression in LSCS/DM is associated with increased levels and activation of M1 pro-inflammatory pathways. Interestingly, C3 and C4b members of the complement complex and mannose receptor-like protein (CLEC18) paralogous proteins were detectable solely at the LSCS/DM patients' samples. Histology analysis shows that inflammatory was induced by the hyperglycemic conditions in diabetic patients involve in altering the matrix compositions. Thus, the protein profiles associated with inflammatory pathways affecting the LF suggested increasing susceptibility of developing the degeneration under hyperglycemic conditions.

Fibroblast Growth Factor 2 Enhances Tendon-to-Bone Healing in a Rat Rotator Cuff Repair of Chronic Tears

BACKGROUND

The effects of fibroblast growth factor 2 (FGF-2) on healing after surgical repair of chronic rotator cuff (RC) tears remain unclear.

HYPOTHESIS

FGF-2 enhances tenogenic healing response, leading to biomechanical and histological improvement of repaired chronic RC tears in rats.

STUDY DESIGN

Controlled laboratory study.

METHODS

Adult male Sprague-Dawley rats (n = 117) underwent unilateral surgery to refix the supraspinatus tendon to its insertion site 3 weeks after detachment. Animals were assigned to either the FGF-2 group or a control group. The effects of FGF-2 were assessed via biomechanical tests at 3 weeks after detachment and at 6 and 12 weeks postoperatively and were assessed histologically and immunohistochemically for proliferating cell nuclear antigen and mesenchymal stem cell (MSC)-related markers at 2, 6, and 12 weeks postoperatively. The expression of tendon/enthesis-related markers, including SRY-box 9 (Sox9), scleraxis (Scx), and tenomodulin (Tnmd), were assessed by real-time reverse transcription polymerase chain reaction, in situ hybridization, and immunohistochemistry. The effect of FGF-2 on comprehensive gene expressions at the healing site was evaluated by microarray analysis.

RESULTS

The FGF-2 group showed a significant increase in mechanical strength at 6 and 12 weeks compared with control; the FGF-2 group also showed significantly higher histological scores at 12 weeks than control, indicating the presence of more mature tendon-like tissue. At 12 weeks, Scx and Tnmd expression increased significantly in the FGF-2 group, whereas no significant differences in Sox9 were found between groups over time. At 2 weeks, the percentage of positive cells expressing MSC-related markers increased in the FGF-2 group. Microarray analysis at 2 weeks after surgery showed that the expression of several growth factor genes and extracellular matrix-related genes was influenced by FGF-2 treatment.

CONCLUSION

FGF-2 enhanced the formation of tough tendon-like tissues including an increase in Scx- or Tnmd-expressing cells at 12 weeks after surgical repair of chronic RC tears. The increase in mesenchymal progenitors and the changes in gene expression upon FGF-2 treatment in the early phase of healing appear to be related to a certain favorable microenvironment for tenogenic healing response of chronic RC tears.

CLINICAL RELEVANCE

These findings may provide advantages in therapeutic strategies for patients with RC tears.

Short-term Changes After Corticosteroid Injections Into the Normal Tendons of Rabbits: A Controlled Randomized Study

BACKGROUND

Corticosteroid injections in or around tendons for the treatment of athletic injuries are a common practice among orthopaedic surgeons and are apparently efficacious in the short term, although controversies persist related to local complications.

PURPOSE

This study evaluated short-term (48 hours) biomechanical, biochemical, and histological alterations after a single injection of betamethasone into the normal tendons of rabbits.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 72 New Zealand White rabbits were randomly divided into 2 groups: the test group-in which 36 animals underwent 1 intratendinous injection of betamethasone (1.4 mg / 0.2 mL) in the right calcaneal tendon; the control group-in which the right calcaneal tendon of 36 animals was injected with saline (placebo control group) and the left calcaneal tendon was left untreated for normal standards (normal control). Forty-eight hours later, animals were euthanized and tendons were harvested. Metalloproteinase (MMP1 and MMP2) and interleukin (IL1 and IL6) expression levels, biomechanical resistance (load × elongation parameters), and histomorphometry (hematoxylin and eosin and picrosirius red stains for collagen fibers, tenocytes, and inflammatory cells) were analyzed in the tendons.

RESULTS

The test group had a significant reduction in MMP2 expression as compared with the control groups ( P = .027). Regarding the other parameters, there were no additional significant differences between the groups.

CONCLUSION

A single injection of corticosteroid into normal calcaneal tendons did not trigger acute local morphological, structural, or biomechanical injuries at 48 hours, but it did promote a significant decrease in MMP2 levels. Additional studies are needed with increased duration of follow-up, various doses, and multiple injections and in tendinopathic models.

CLINICAL RELEVANCE

Some previous studies demonstrated early structural changes in tendons after a single corticosteroid injection, which was not corroborated by the present study. Metalloproteinase decrease is usually associated with a reduction in collagen degradation, which would be protective for the healing process. More studies are necessary to confirm the possible beneficial effect of these results in the long term and for tendinopathies.

Subacromial decompression surgery for rotator cuff disease

BACKGROUND

Surgery for rotator cuff disease is usually used after non-operative interventions have failed, although our Cochrane Review, first published in 2007, found that there was uncertain clinical benefit following subacromial decompression surgery.

OBJECTIVES

To synthesise the available evidence of the benefits and harms of subacromial decompression surgery compared with placebo, no intervention or non-surgical interventions in people with rotator cuff disease (excluding full thickness rotator cuff tears).

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, Clinicaltrials.gov and WHO ICRTP registry from 2006 until 22 October 2018, unrestricted by language.

SELECTION CRITERIA

We included randomised and quasi-randomised controlled trials (RCTs) of adults with rotator cuff disease (excluding full-thickness tears), that compared subacromial decompression surgery with placebo, no treatment, or any other non-surgical interventions. As it is least prone to bias, subacromial decompression compared with placebo was the primary comparison. Other comparisons were subacromial decompression versus exercises or non-operative treatment. Major outcomes were mean pain scores, shoulder function, quality of life, participant global assessment of success, adverse events and serious adverse events. The primary endpoint for this review was one year. For serious adverse events, we also included data from prospective cohort studies designed to record harms that evaluated subacromial decompression surgery or shoulder arthroscopy.

DATA COLLECTION AND ANALYSIS

We used standard methodologic procedures expected by Cochrane.

MAIN RESULTS

We included eight trials, with a total of 1062 randomised participants with rotator cuff disease, all with subacromial impingement. Two trials (506 participants) compared arthroscopic subacromial decompression with arthroscopy only (placebo surgery), with all groups receiving postoperative exercises. These trials included a third treatment group: no treatment (active monitoring) in one and exercises in the other. Six trials (556 participants) compared arthroscopic subacromial decompression followed by exercises with exercises alone. Two of these trials included a third arm: sham laser in one and open subacromial decompression in the other.Trial size varied from 42 to 313 participants. Participant mean age ranged between 42 and 65 years. Only two trials reported mean symptom duration (18 to 22 months in one trial and 30 to 31 months in the other), two did not report duration and four reported it categorically.Both placebo-controlled trials were at low risk of bias for the comparison of surgery versus placebo surgery. The other trials were at high risk of bias for several criteria, most notably at risk of performance or detection bias due to lack of participant and personnel blinding. We have restricted the reporting of results of benefits in the Abstract to the placebo-controlled trials.Compared with placebo, high-certainty evidence indicates that subacromial decompression provides no improvement in pain, shoulder function, or health-related quality of life up to one year, and probably no improvement in global success (moderate-certainty evidence, downgraded due to imprecision).At one year, mean pain (on a scale zero to 10, higher scores indicate more pain), was 2.9 points after placebo surgery and 0.26 better (0.84 better to 0.33 worse), after subacromial decompression (284 participants), an absolute difference of 3% (8% better to 3% worse), and relative difference of 4% (12% better to 5% worse). At one year, mean function (on a scale 0 to 100, higher score indicating better outcome), was 69 points after placebo surgery and 2.8 better (1.4 worse to 6.9 better), after surgery (274 participants), an absolute difference of 3% (7% better to 1% worse), and relative difference of 9% (22% better to 4% worse). Global success rate was 97/148 (or 655 per 1000), after placebo and 101/142 (or 708 per 1000) after surgery corresponding to RR 1.08 (95% CI 0.93 to 1.27). Health-related quality of life was 0.73 units (European Quality of Life EQ-5D, -0.59 to 1, higher score indicating better quality of life), after placebo and 0.03 units worse (0.011 units worse to 0.06 units better), after subacromial decompression (285 participants), an absolute difference of 1.3% (5% worse to 2.5% better), and relative difference of 4% (15% worse to 7% better).Adverse events including frozen shoulder or transient minor complications of surgery were reported in approximately 3% of participants across treatment groups in two randomised controlled trials, but due to low event rates we are uncertain if the risks differ between groups: 5/165 (37 per 1000) reported adverse events with subacromial decompression and 9/241 (34 per 1000) with placebo or non-operative treatment, RR 0.91 (95% CI 0.31 to 2.65) (moderate-certainty evidence, downgraded due to imprecision). The trials did not report serious adverse events.Based upon moderate-certainty evidence from two observational trials from the same prospective surgery registry, which also included other shoulder arthroscopic procedures (downgraded for indirectness), the incidence proportion of serious adverse events within 30 days following surgery was 0.5% (0.4% to 0.7%; data collected 2006 to 2011), or 0.6% (0.5 % to 0.7%; data collected 2011 to 2013). Serious adverse events such as deep infection, pulmonary embolism, nerve injury, and death have been observed in participants following shoulder surgery.

AUTHORS' CONCLUSIONS

The data in this review do not support the use of subacromial decompression in the treatment of rotator cuff disease manifest as painful shoulder impingement. High-certainty evidence shows that subacromial decompression does not provide clinically important benefits over placebo in pain, function or health-related quality of life. Including results from open-label trials (with high risk of bias) did not change the estimates considerably. Due to imprecision, we downgraded the certainty of the evidence to moderate for global assessment of treatment success; there was probably no clinically important benefit in this outcome either compared with placebo, exercises or non-operative treatment.Adverse event rates were low, 3% or less across treatment groups in the trials, which is consistent with adverse event rates reported in the two observational studies. Although precise estimates are unknown, the risk of serious adverse events is likely less than 1%.

SUPRASPINATUS TENDON PATHOMECHANICS: A CURRENT CONCEPTS REVIEW

BACKGROUND AND PURPOSE

Tendinopathy of the supraspinatus muscle is a frequent cause of shoulder pain. Although it is a common condition, the pathophysiology is not fully understood. The purpose of this clinical commentary is to provide an overview of the pathophysiology of supraspinatus tendinopathy and discuss the conservative treatment solutions.

DESCRIPTION

Supraspinatus tendinopathy is thought to be caused by both intrinsic, and extrinsic factors. Structural and biological changes happen when tendinopathy develops. Cellular and extracellular modifications characterize tendon healing stages that continue over time. Assessment is paramount in order to differentiate the structure involved, and to offer a proper treatment solution.

RELATION TO CLINICAL PRACTICE

Knowledge of the general concepts regarding the development of supraspinatus tendinopathy, and of the healing process should guide physiotherapists when proposing treatment options. Physical modalities commonly utilized for supraspinatus tendinopathy such as: laser, ultrasound, and shock-wave therapy have little and contradictory evidence. Exercise in form of eccentric training may be considered as it seems to have beneficial effects, however, more research is needed.

Tendinopathy: Investigating the Intersection of Clinical and Animal Research to Identify Progress and Hurdles in the Field

Biological treatments, surgical interventions, and rehabilitation exercises have been successfully used to treat tendinopathy, but the development of effective treatments has been hindered by the lack of mechanistic data regarding the pathogenesis of the disease. While insightful, clinical studies are limited in their capacity to provide data regarding the pathogenesis of tendinopathies, emphasizing the value of animal models and cell culture studies to fill this essential gap in knowledge. Clinical pathological findings from imaging studies or histological analysis are not universal across patients with tendinopathy and have not been clearly associated with the onset of symptoms. There are several unresolved controversies, including the cellular changes that accompany the tendinopathic disease state and the role of inflammation. Additional research is needed to correlate the manifestations of the disease with its pathogenesis, with the goal of reaching a field-wide consensus on the pathology of the disease state. Such a consensus will allow standardized clinical practices to more effectively diagnose and treat tendinopathy.

A Systematic Summary of Systematic Reviews on the Topic of the Rotator Cuff

BACKGROUND

The number of systematic reviews and meta-analyses published on the rotator cuff (RC) has increased markedly.

PURPOSE

To quantify the number of systematic reviews and meta-analyses published on the RC and to provide a qualitative summary of the literature.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

A systematic search for all systematic reviews and meta-analyses pertaining to the RC published between January 2007 and September 2017 was performed with PubMed, MEDLINE, and the Cochrane Database of Systematic Reviews. Narrative reviews and non-English language articles were excluded.

RESULTS

A total of 1078 articles were found, of which 196 met the inclusion criteria. Included articles were summarized and divided into 15 topics: anatomy and function, histology and genetics, diagnosis, epidemiology, athletes, nonoperative versus operative treatment, surgical repair methods, concomitant conditions and surgical procedures, RC tears after total shoulder arthroplasty, biological augmentation, postoperative rehabilitation, outcomes and complications, patient-reported outcome measures, cost-effectiveness of RC repair, and quality of randomized controlled trials.

CONCLUSION

A qualitative summary of the systematic reviews and meta-analyses published on the RC can provide surgeons with a single source of the most current literature.

Changes in the expression of matrix extracellular genes and TGFB family members in rotator cuff tears

Lack of synthesis of extracellular matrix compounds may contribute to degeneration of the tendons. Thus, we aimed to evaluate the expression of extracellular matrix and TGFB family members in ruptured and non-ruptured tendons of the rotator cuff, as well as the effect of clinical factors on gene expression in tendon samples, and the relationship between histological findings and altered gene expression. Injured and non-injured supraspinatus tendon samples and subscapular non-injured tendon samples were collected from 38 patients with rotator cuff tears. Non-injured supraspinatus tendons were obtained from eight controls. Specimens were used for histological evaluation, quantification of collagen fibers, and mRNA and protein expression analyses. Increased COL1A1, COL1A2, COL3A1, COL5A1, FN1, TNC, and TGFBR1 mRNA expression was observed in the tear samples (p < 0.05). Duration of symptoms was correlated with the levels of collagen type I/III fibers (p = 0.032; ρ = 0.0447) and FN1 immunostaining (p = 0.031; ρ = 0.417). Smoking was associated with increased frequency of microcysts, myxoid degeneration, and COL5A1, FN1, TNC, and TGFB1 mRNA expression (p < 0.05). FN1 immunostaining was correlated with the number of years of smoking (p = 0.048; ρ = 0.384). Lower levels of collagen type I/III fibers were detected in samples with fissures (0 = 0.046). High frequency of microcysts was associated with increased COL5A1, FN1, and TNC expression (p < 0.05, for all comparisons). Neovascularization was associated with reduced FN1 (p = 0.035) and TGFBR1 expression (p = 0.034). Our findings show differential expression of matrix extracellular genes and TGFB family members in the degeneration process involved in rotator cuff tears. These molecular alterations are influenced by clinical factors. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2542-2553, 2018.

Enthesis Repair: Challenges and Opportunities for Effective Tendon-to-Bone Healing

On May 22, 2017, the National Institutes of Health (NIH)/National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) hosted a roundtable on "Innovative Treatments for Enthesis Repair." A summary of the roundtable discussion, as well as a list of the extramural participants, can be found at https://www.niams.nih.gov/about/meetings-events/roundtables/roundtable-innovative-treatments-enthesis-repair. This paper reviews the challenges and opportunities for developing effective treatment strategies for enthesis repair that were identified at the roundtable discussion.

Trends in the theory that inflammation plays a causal role in tendinopathy: a systematic review and quantitative analysis of published reviews

BACKGROUND/AIMS

The contribution of inflammation to tendinopathy has been debated in the scientific literature. Several factors may contribute to this lack of clarity, including inconsistent definitions of inflammation. We hypothesised that the adoption and/or rejection of a causal link between inflammation and tendinopathy varied as a function of the 'inflammatory component' (eg, immune cell and molecular mediators included in published reviews).

METHODS

Twenty data items were collected from each review to determine conclusions about the role of inflammation in tendinopathy, specific definitions of the 'inflammatory component,' quality of the review and other potential correlates. Associations between correlates and a review's conclusion about the role of inflammation in tendinopathy were tested using binomial logistic regression. The database searches retrieved 2261 unique publications: 137 fulfilled inclusion criteria after full text screenings.

RESULTS

There has been little support for an inflammatory component to tendinopathy until recently (2012-2015). Prior to 2012, the majority of published reviews did not discuss monocytes, macrophages or lymphocytes in tendinopathy; rather they focused on the lack of neutrophils, often referred to as 'the inflammatory infiltrate', or immune cells were not discussed. Reviews including monocytes and lymphocytes in their discussions were 5.23 times more likely to conclude inflammation was important than reviews that did not, p<0.001.

CONCLUSIONS

Data collected show growing support for an inflammatory component to tendinopathy, particularly among high-quality reviews and those that used more robust definitions of inflammation. This finding may have implications for explaining dissonance in the literature regarding a causal role for inflammation in the pathogenesis of tendinopathy.

Ultrasonographic Findings in 41 Dogs Treated with Bone Marrow Aspirate Concentrate and Platelet-Rich Plasma for a Supraspinatus Tendinopathy: A Retrospective Study

Objective

To report sonographic findings for dogs with a supraspinatus tendinopathy (ST) treated with an ultrasound-guided intratendinous injection of bone marrow aspirate concentrate (BMAC) and platelet-rich plasma (PRP).

Methods

Medical records for dogs diagnosed with an ST and treated with a BMAC-PRP injection were reviewed. Data collected included patient signalment, radiographic findings at the time of initial evaluation, and sonographic findings, including cross-sectional area (CSA), fiber pattern, and echogenicity.

Results

Of 70 records reviewed, 41 met the inclusion criteria. Mean CSA of the supraspinatus tendon decreased by 0.06 cm² between baseline and 45 days post-treatment (p = 0.0025), and 0.09 cm² between baseline and 90 days post-treatment (p < 0.0001). Analysis of CSA in dogs with a unilateral ST at baseline revealed a difference of 0.08 cm² between the affected and unaffected tendon at baseline, with the affected tendon measuring larger than the contralateral tendon (p < 0.0001). This difference became statistically insignificant by 45 days after treatment (u₁-u₀ = 0.04 cm², p = 0.2855) and remained so 90 days post-treatment (u₁-u₀ = 0.03 cm², p = 0.1910). In most cases (90.6%), the fiber pattern and echogenicity was considered improved 90 days post treatment. In a minority of these cases (13.8%) the fiber pattern and echogenicity abnormalities were considered resolved.

Conclusions

Using qualitative and quantitative sonographic measures, BMAC-PRP was associated with an improvement in supraspinatus tendon size, fiber pattern, and echogenicity. Given the protracted nature of tendon healing, long-term evaluation may reveal continued improvements in chronic structural changes not captured during the current study. Functional studies are required to evaluate the clinical benefits of BMAC-PRP in the treatment of STs in dogs.

Clinical significance

An ST is a common contributor to forelimb lameness in dogs and remains notoriously difficult to treat. Previous studies have been associated with inconsistent treatment outcomes. In the current study, BMAC-PRP is investigated as a minimally invasive treatment option, revealing positive sonographic results.

Supraspinatus tendon micromorphology in individuals with subacromial pain syndrome

STUDY DESIGN

Cross-sectional cohort.

INTRODUCTION

Tendon collagen organization can be estimated by peak spatial frequency radius (PSFR) on ultrasound images. Characterizing PSFR can define the contribution of collagen disruption to shoulder symptoms.

PURPOSE OF THE STUDY

The purpose of this was to characterize the (1) supraspinatus tendon PSFR in participants with subacromial pain syndrome (SPS) and healthy controls; (2) PSFR between participants grouped on a tendon visual quality score; and (3) relationship between PSFR with patient-reported pain, function, and shoulder strength.

METHODS

Participants with SPS (n = 20) and age, sex, and arm-dominance-matched healthy controls (n = 20) completed strength testing in scaption and external rotation, and patient-reported pain, and functional outcomes. Supraspinatus tendon ultrasound images were acquired, and PSFR was calculated for a region of interest 15 mm medial to the supraspinatus footprint. PSFR was compared between groups using an independent t-test and an analysis of variance to compare between 3 groups for visually qualitatively rated tendon abnormalities. Relationships between PSFR with pain, function, and strength were assessed using Pearson correlation coefficient.

RESULTS

Supraspinatus tendon PSFR was not different between groups (P = .190) or tendon qualitative ratings (P = .556). No relationship was found between PSFR and pain, functional loss, and strength (P > .05).

CONCLUSIONS

Collagen disruption (PSFR) measured via ultrasound images of the supraspinatus tendon was not different between participants with SPS or in those with visually rated tendon defects. PSFR is not related to shoulder pain, function, and strength, suggesting that supraspinatus tendon collagen disorganization may not be a contributing factor to shoulder SPS. However, collagen disruption may not be isolated to a single region of interest.

LEVEL OF EVIDENCE

3b: case-control study.

The Strengthening Exercises in Shoulder Impingement trial (The SExSI-trial) investigating the effectiveness of a simple add-on shoulder strengthening exercise programme in patients with long-lasting subacromial impingement syndrome: Study protocol for a pragmatic, assessor blinded, parallel-group, randomised, controlled trial

Background

Subacromial impingement syndrome (SIS) is a painful, and often long lasting, shoulder condition affecting patient function and quality of life. In a recent study, we observed major strength impairments in shoulder external rotation and abduction (~30%) in a population of patients with pronounced and long-lasting SIS. However, the current rehabilitation of such strength impairments may be inadequate, with novel rehabilitation programmes including exercise therapy only improving external rotation strength by 4–13%.

As these previous studies are the basis of current practice, this suggests that the strengthening component could be inadequate in the rehabilitation of these patients, and it seems likely that more emphasis should be placed on intensifying this part of the rehabilitation.

The purpose of this study is to investigate the effectiveness of a programme consisting of progressive home-based resistance training using an elastic band, aimed at improving shoulder external rotation and abduction strength, added to usual care and initiated shortly after diagnosis has been established.

Methods

A pragmatic randomised controlled superiority trial will be conducted, including 200 patients with pronounced and long-lasting SIS, diagnosed using predefined criteria. Participants will be randomised to receive either an add-on intervention of progressive home-based resistance training using an elastic band in addition to usual care or usual care alone in a 1:1 allocation ratio. The randomisation sequence is computer generated, with permuted blocks of random sizes. The primary outcome will be change in Shoulder Pain And Disability Index (SPADI) score from baseline to 16 weeks follow-up. Outcome assessors are blinded to group allocation. Intervention receivers will be kept blind to treatment allocation through minimal information about the content of the add-on intervention and control condition until group allocation is final. Analyses are performed by blinded data analysts.

Discussion

If effective, the simple shoulder strengthening exercise programme investigated in this trial could easily be added to usual care. The usefulness of the trial is further supported by the magnitude of the problem, the information gained from the study and the pragmatism, patient centeredness and transparency of the trial.

Trial registration

The trial is pre-registered at ClinicalTrials.gov with the ID NCT02747251 on April 19, 2016.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2509-7) contains supplementary material, which is available to authorized users.

Cytokines in tendon disease: A Systematic Review

OBJECTIVES

Emerging evidence indicates that tendon disease is an active process with inflammation that is critical to disease onset and progression. However, the key cytokines responsible for driving and sustaining inflammation have not been identified.

METHODS

We performed a systematic review of the literature using MEDLINE (U.S. National Library of Medicine, Bethesda, Maryland) in March 2017. Studies reporting the expression of interleukins (ILs), tumour necrosis factor alpha (TNF-α) and interferon gamma in diseased human tendon tissues, and animal models of tendon injury or exercise in comparison with healthy control tissues were included.

RESULTS

IL-1β, IL-6, IL-10, and TNF-α are the cytokines that have been most frequently investigated. In clinical samples of tendinopathy and tendon tears, the expression of TNF-α tended not to change but IL-6 increased in tears. Healthy human tendons showed increased IL-6 expression after exercise; however, IL-10 remained unchanged. Animal tendon injury models showed that IL-1β, IL-6, and TNF-α tend to increase from the early phase of tendon healing. In animal exercise studies, IL-1β expression showed a tendency to increase at the early stage after exercise, but IL-10 expression remained unchanged with exercise.

CONCLUSIONS

This review highlights the roles of IL-1β, IL-6, IL-10, and TNF-α in the development of tendon disease, during tendon healing, and in response to exercise. However, there is evidence accumulating that suggests that other cytokines are also contributing to tendon inflammatory processes. Further work with hypothesis-free methods is warranted in order to identify the key cytokines, with subsequent mechanistic and interaction studies to elucidate their roles in tendon disease development.Cite this article: W. Morita, S. G. Dakin, S. J. B. Snelling, A. J. Carr. Cytokines in tendon disease: A Systematic Review. Bone Joint Res 2017;6:656-664. DOI: 10.1302/2046-3758.612.BJR-2017-0112.R1.

Epigenetic regulation of metalloproteinases and their inhibitors in rotator cuff tears

Rotator cuff tear is a common orthopedic condition. Metalloproteinases (MMP) and their inhibitors (TIMP) seem to play a role in the development of joint injuries and in the failure of tissue healing. However, the mechanisms of regulation of gene expression in tendons are still unknown. Epigenetic mechanisms, such as DNA methylation and microRNAs regulation, are involved in the dynamic control of gene expression. Here, the mRNA expression and DNA methylation status of MMPs (MMP1, MMP2, MMP3, MMP9, MMP13, and MMP14) and TIMPs (TIMP1-3) and the expression of miR-29 family members in ruptured supraspinatus tendons were compared with non-injured tendons of individuals without this lesion. Additionally, the gene expression and methylation status at the edge of the ruptured tendon were compared with macroscopically non-injured rotator cuff tendon samples from the anterior and posterior regions of patients with tendon tears. Moreover, the possible associations between the molecular alterations and the clinical and histologic characteristics were investigated. Dysregulated expression and DNA methylation of MMP and TIMP genes were found across the rotator cuff tendon samples of patients with supraspinatus tears. These alterations were influenced at least in part by age at surgery, sex, smoking habit, tear size, and duration of symptoms. Alterations in the studied MMP and TIMP genes may contribute to the presence of microcysts, fissures, necrosis, and neovascularization in tendons and may thus be involved in the tendon healing process. In conclusion, MMPs and their inhibitors are regulated by epigenetic modifications and may play a role in rotator cuff tears.

Three Months of Progressive High-Load Versus Traditional Low-Load Strength Training Among Patients With Rotator Cuff Tendinopathy: Primary Results From the Double-Blind Randomized Controlled RoCTEx Trial

Background:

Progressive high-load exercise (PHLE) has led to positive clinical results in patients with patellar and Achilles tendinopathy. However, its effects on rotator cuff tendinopathy still need to be investigated.

Purpose:

To assess the clinical effects of PHLE versus low-load exercise (LLE) among patients with rotator cuff tendinopathy.

Study Design:

Randomized controlled trial; Level of evidence, 1.

Methods:

Patients with rotator cuff tendinopathy were recruited and randomized to 12 weeks of PHLE or LLE, stratified for concomitant administration of corticosteroid injection. The primary outcome measure was change from baseline to 12 weeks in the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire, assessed in the intention-to-treat population.

Results:

A total of 100 patients were randomized to PHLE (n = 49) or LLE (n = 51). Mean changes in the DASH questionnaire were 7.11 points (95% CI, 3.07-11.16) and 8.39 points (95% CI, 4.35-12.44) in the PHLE and LLE groups, respectively; this corresponded to a statistically nonsignificant adjusted mean group difference of −1.37 points (95% CI, −6.72 to 3.99; P = .61). Similar nonsignificant results were seen for pain, range of motion, and strength. However, a significant interaction effect was found between the 2 groups and concomitant corticosteroid use (P = .028), with the largest positive change in DASH in favor of PHLE for the group receiving concomitant corticosteroid.

Conclusion:

The study results showed no superior benefit from PHLE over traditional LLE among patients with rotator cuff tendinopathy. Further investigation of the possible interaction between exercise type and corticosteroid injection is needed to establish optimal and potentially synergistic combinations of these 2 factors.

Registration:

NCT01984203 (ClinicalTrials.gov identifier): Rotator Cuff Tendinopathy Exercise Trial (RoCTEx).