More tendon degeneration in patients with shoulder osteoarthritis

Translational genomics of osteoarthritis in 1,962,069 individuals

Osteoarthritis is the third most rapidly growing health condition associated with disability, after dementia and diabetes1. By 2050, the total number of patients with osteoarthritis is estimated to reach 1 billion worldwide2. As no disease-modifying treatments exist for osteoarthritis, a better understanding of disease aetiopathology is urgently needed. Here we perform a genome-wide association study meta-analyses across up to 489,975 cases and 1,472,094 controls, establishing 962 independent associations, 513 of which have not been previously reported. Using single-cell multiomics data, we identify signal enrichment in embryonic skeletal development pathways. We integrate orthogonal lines of evidence, including transcriptome, proteome and epigenome profiles of primary joint tissues, and implicate 700 effector genes. Within these, we find rare coding-variant burden associations with effect sizes that are consistently higher than common frequency variant associations. We highlight eight biological processes in which we find convergent involvement of multiple effector genes, including the circadian clock, glial-cell-related processes and pathways with an established role in osteoarthritis (TGFβ, FGF, WNT, BMP and retinoic acid signalling, and extracellular matrix organization). We find that 10% of the effector genes express a protein that is the target of approved drugs, offering repurposing opportunities, which can accelerate translation.

Effects of adipose allograft matrix on viability of humeral head cartilage and rotator cuff tendon

BACKGROUND

Rotator cuff repairs may fail because of compromised blood supply, suture anchor pullout, or poor fixation to bone. To augment the repairs and promote healing of the tears, orthobiologics, such a platelet-rich plasma (PRP), and biologic scaffolds have been applied with mixed results. Adipose allograft matrix (AAM), which recruits native cells to damaged tissues, may also be a potential treatment for rotator cuff tears.

METHODS

To assess the potential use of AAM on rotator cuff tears, humeral head cartilage and subscapularis tendon were collected from patients undergoing reverse shoulder arthroplasty (RSA). Punch biopsies of the tissues were used to create explants for tissue culture, and the remaining tissue was digested to isolate the chondrocytes and tenocytes for cell culture. Explants and cells were then cultured in media containing AAM. After 48 h, the tissues and cells were measured for cell viability, cell proliferation, extracellular matrix (ECM) and metalloproteinase (MMP) gene expression and for MMP, inflammatory cytokine, and growth factor concentrations.

RESULTS

Cell viability was increased in humeral head chondrocytes and rotator cuff tenocytes cultured with AAM. Gene expression of the matrix proteoglycan, aggrecan, and of the proteolytic enzyme MMP-13 were downregulated in humeral head chondrocytes. MMP-13 concentrations were increased in subscapularis tenocytes and in humeral head chondrocyte/subscapularis tenocyte co-cultures. The anti-inflammatory cytokine, IL-1ra was increased in cartilage/tendon explant co-cultures. TGF-β1 concentrations were increased in chondrocytes, but decreased in tenocytes.

CONCLUSIONS

Overall, AAM had no significant negative effects on the cells or explants. The results of these experiments provide the basis for the future use of AAM as a scaffolding for tissue engineering, preclinical animal models of rotator cuff tear and glenohumeral osteoarthritis, and clinical models.

CLINICAL TRIAL NUMBER

Not applicable.

Defining the extracellular matrix in non-cartilage soft-tissues in osteoarthritis: a systematic review

Aims

Extracellular matrix (ECM) is a critical determinant of tissue mechanobiology, yet remains poorly characterized in joint tissues beyond cartilage in osteoarthritis (OA). This review aimed to define the composition and architecture of non-cartilage soft joint tissue structural ECM in human OA, and to compare the changes observed in humans with those seen in animal models of the disease.

Methods

A systematic search strategy, devised using relevant matrix, tissue, and disease nomenclature, was run through the MEDLINE, Embase, and Scopus databases. Demographic, clinical, and biological data were extracted from eligible studies. Bias analysis was performed.

Results

A total of 161 studies were included, which covered capsule, ligaments, meniscus, skeletal muscle, synovium, and tendon in both humans and animals, and fat pad and intervertebral disc in humans only. These studies covered a wide variety of ECM features, including individual ECM components (i.e. collagens, proteoglycans, and glycoproteins), ECM architecture (i.e. collagen fibre organization and diameter), and viscoelastic properties (i.e. elastic and compressive modulus). Some ECM changes, notably calcification and the loss of collagen fibre organization, have been extensively studied across osteoarthritic tissues. However, most ECM features were only studied by one or a few papers in each tissue. When comparisons were possible, the results from animal experiments largely concurred with those from human studies, although some findings were contradictory.

Conclusion

Changes in ECM composition and architecture occur throughout non-cartilage soft tissues in the osteoarthritic joint, but most of these remain poorly defined due to the low number of studies and lack of healthy comparator groups.

A new frontier in temporomandibular joint osteoarthritis treatment: Exosome-based therapeutic strategy

Temporomandibular joint osteoarthritis (TMJOA) is a debilitating degenerative disease with high incidence, deteriorating quality of patient life. Currently, due to ambiguous etiology, the traditional clinical strategies of TMJOA emphasize on symptomatic treatments such as pain relief and inflammation alleviation, which are unable to halt or reverse the destruction of cartilage or subchondral bone. A number of studies have suggested the potential application prospect of mesenchymal stem cells (MSCs)-based therapy in TMJOA and other cartilage injury. Worthy of note, exosomes are increasingly being considered the principal efficacious agent of MSC secretions for TMJOA management. The extensive study of exosomes (derived from MSCs, synoviocytes, chondrocytes or adipose tissue et al.) on arthritis recently, has indicated exosomes and their specific miRNA components to be potential therapeutic agents for TMJOA. In this review, we aim to systematically summarize therapeutic properties and underlying mechanisms of MSCs and exosomes from different sources in TMJOA, also analyze and discuss the approaches to optimization, challenges, and prospects of exosome-based therapeutic strategy.

Breakthrough of extracellular vesicles in pathogenesis, diagnosis and treatment of osteoarthritis

Osteoarthritis (OA) is a highly prevalent whole-joint disease that causes disability and pain and affects a patient's quality of life. However, currently, there is a lack of effective early diagnosis and treatment. Although stem cells can promote cartilage repair and treat OA, problems such as immune rejection and tumorigenicity persist. Extracellular vesicles (EVs) can transmit genetic information from donor cells and mediate intercellular communication, which is considered a functional paracrine factor of stem cells. Increasing evidences suggest that EVs may play an essential and complex role in the pathogenesis, diagnosis, and treatment of OA. Here, we introduced the role of EVs in OA progression by influencing inflammation, metabolism, and aging. Next, we discussed EVs from the blood, synovial fluid, and joint-related cells for diagnosis. Moreover, we outlined the potential of modified and unmodified EVs and their combination with biomaterials for OA therapy. Finally, we discuss the deficiencies and put forward the prospects and challenges related to the application of EVs in the field of OA.

Arthritis Severity and Medical Comorbidities Are Prognostic of Worse Outcomes Following Arthroscopic Rotator Cuff Repair in Patients With Concomitant Glenohumeral Osteoarthritis

Purpose

To assess demographic factors, comorbidities, radiographic variables, and injury patterns as potential prognostic indicators of poor functional and patient-reported outcomes following arthroscopic rotator cuff repair in patients with concomitant glenohumeral osteoarthritis.

Methods

A retrospective review of consecutive patients with glenohumeral osteoarthritis who underwent arthroscopic supraspinatus repairs between 2013 and 2018 with a minimum of 1-year follow up was performed. Demographic variables included age, tobacco use, alcohol use, diabetes, sex, hypercholesterolemia, and body mass index while injury patterns included partial- versus full-thickness tear, bicep tendon involvement, and osteoarthritis severity. Multivariate linear regression was used to identify independent predictors of visual analog pain scale (VAS), subjective shoulder value (SSV), and American Shoulder and Elbow Surgeons (ASES) score as well as active range of motion (ROM) in forward flexion (FF) and external rotation (ER). Binary logistic regression was used to identify predictors of repair failure as well as postoperative strength in FF and ER.

Results

In total, 91 patients (mean age 61.48 ± 9.4 years) were identified with an average follow up of 26.3 ± 5.7 months. Repair failures occurred in 9.9% (9/91 patients) of the total cohort. Postoperative outcomes were significantly improved with regards to visual analog pain scale, subjective shoulder value, ASES score, ROM in FF, FF strength, and external rotation strength compared with preoperative baseline. Obesity (P = .023) and diabetes (P = .010) were significant independent predictors of greater pain scores postoperatively. Obesity (P = .029) and tobacco use (P = .007) were significant predictors of lower ASES scores postoperatively. Finally, moderate-to-severe osteoarthritis was a significant risk factor for poor ROM and strength in FF postoperatively compared to mild osteoarthritis (P = .029). No variables were predictive of repair failure.

Conclusions

Tobacco use, obesity, and diabetes are associated with worse pain and patient-reported outcomes following arthroscopic rotator cuff repair in the context of glenohumeral OA. In addition, moderate-to-severe OA is associated with worse strength and forward flexion compared to those with mild OA.

Level of Evidence

Level III, retrospective cohort study.

An interexaminer agreement and reliability study on cadavers with musculoskeletal ultrasound of the shoulder performed by physiotherapists and radiologists compared with dissection

STUDY DESIGN

A cross-sectional inter-examiner agreement and reliability study on fresh frozen cadaver shoulders.

BACKGROUND

Musculoskeletal ultrasound (MSU) is frequently used by physical therapists and radiologists to improve specific diagnosis in rotator cuff related pathology. The evaluation of the rotator cable seems to be important as stabilizing structure when cuff tears occur.

OBJECTIVES

To evaluate the inter-examiner agreement and reliability of MSU of the shoulder to detect rotator cuff-pathology and the involvement of the rotator cable in comparison to "dissection".

METHODS

Physical therapists, a radiologist and an orthopedic surgeon (dissection) investigated 40 fresh frozen cadaver shoulders in order to detect shoulder pathology including rotator cable involvement. Examiners were blinded to each other's findings.

RESULTS

We found a strong and significant agreement between the raters: PTs, the radiologist and the dissector in this cadaver study for all rotator cuff, the long head of the biceps pathologies and in detecting abnormalities of the rotator cable. The kappa value was substantial to (almost) perfect agreement for all diagnostic outcome categories.

CONCLUSIONS

This study shows that among a limited group of physical therapists, one radiologist and a dissector a strong level of agreement with kappa values from substantial to (almost) perfect in finding subacromial pathology.

Clinical outcomes of rotator cuff repair in patients with concomitant glenohumeral osteoarthritis

BACKGROUND

Glenohumeral osteoarthritis (OA) is a common comorbidity in patients with rotator cuff tears. However, the efficacy of rotator cuff repair in patients with concomitant glenohumeral OA is still heavily debated. Thus, the purpose of this study was to compare the clinical and functional outcome measures following arthroscopic rotator cuff repairs in patients with concomitant glenohumeral OA vs. those without glenohumeral OA.

METHODS

A retrospective review of 206 consecutive patients who underwent arthroscopic supraspinatus repairs (both isolated and with accompanying infraspinatus and/or subscapularis involvement) between 2013 and 2018 with a minimum of 1-year follow-up was performed. Patients were separated into 2 groups based on the presence or absence of concomitant glenohumeral OA. The primary outcome was failure of repair, defined as the need for revision repair or a retear confirmed on postoperative magnetic resonance imaging. The secondary outcomes were patient-reported outcome measures including the visual analog scale pain score, Subjective Shoulder Value, and American Shoulder and Elbow Surgeons score; active range of motion (ROM); and strength testing. Within the OA cohort, a subgroup analysis was conducted to compare outcomes between patients with mild OA and patients with moderate to severe OA.

RESULTS

There were 91 patients in the glenohumeral OA group and 115 patients in the control group. Significant differences in postoperative forward flexion (FF) ROM (153.55° ± 21.07° vs. 160.14° ± 17.26°, P = .001) and external rotation (ER) ROM (46.91° ± 11.95° vs. 52.25° ± 11.60°, P = .001) were observed between the glenohumeral OA and control groups. There were no significant differences between groups in revision repairs, retears, postoperative internal rotation ROM, all preoperative ROMs, all patient-reported outcome measures, and all strength parameters (all P > .05). For the subgroup analysis, there were 70 patients in the mild OA group and 21 patients in the moderate to severe OA group. We found a significant difference in postoperative FF strength (88.4% vs. 61.9% with 5 of 5 strength, P = .010) and ER strength (89.9% vs. 71.4% with 5 of 5 strength, P = .046) between the mild OA group and moderate to severe OA group. There were no significant differences between the groups in all other outcome measures.

DISCUSSION

Rotator cuff repair remains an excellent treatment option in patients with concomitant glenohumeral OA. The data in this study demonstrate that rotator cuff repairs in patients with concomitant glenohumeral OA have similar clinical and functional outcomes to repairs in patients without OA with the exception of slightly decreased postoperative FF and ER ROM. Patients with moderate to severe OA may have slightly decreased FF and ER strength outcomes compared with patients with mild OA.

The role of the long head of the biceps tendon in posterior shoulder stabilization during forward flexion

BACKGROUND

The role of the long head of the biceps tendon (LHBT) in glenohumeral stability is not fully understood. Most objects are lifted in the sagittal plane with forward flexion, which stresses the posterior aspect of the unconstrained glenohumeral joint. Determining the mechanism by which the shoulder maintains stability with functional motions is important to understanding the pathoanatomy of degenerative shoulders. Our hypothesis was that the LHBT resists posterior translation of the humeral head (HH) during forward flexion by tensioning the posterior capsuloligamentous complex.

METHODS

Ten fresh-frozen cadaveric shoulders were tested using an established shoulder simulator that loads the LHBT, rotator cuff, and deltoid tendons through a system of pulleys. A motion tracking system recorded glenohumeral translations with an accuracy of ±0.2 mm. In each subject, the scapula was fixed and the humerus was tested in 6 positions: 30° and 60° of glenohumeral forward flexion at (1) maximum internal rotation (IR), (2) neutral rotation, and (3) maximum external rotation (ER). The deltoid was loaded with 100 N, and the infraspinatus and subscapularis were loaded with 22 N each. The difference in glenohumeral translation was calculated at each position comparing the LHBT loaded with 45 N or unloaded.

RESULTS

At 30° of glenohumeral forward flexion, unloading the LHBT increased HH posterior translation by 2.5 mm (±0.9 mm; P < .001), 1.7 mm (±1.0 mm; P < .001), and 1.0 mm (±0.9 mm; P = .01) at maximum ER, neutral rotation, and maximum IR, respectively. At 60° of glenohumeral forward flexion, unloading the LHBT increased HH posterior translation by 2.8 mm (±1.2 mm; P < .001), 2.4 mm (±1.6 mm; P < .001), and 1.7 mm (±1.4 mm; P < .001) at maximum ER, neutral rotation, and maximum IR, respectively.

CONCLUSION

LHBT loading resists posterior translation of the HH during forward flexion. These data support the role of the LHBT as a posterior stabilizer of the shoulder, specifically when a person is carrying objects in front of them. Further work is needed to determine if unloading the LHBT, as is done with biceps tenotomy or tenodesis, may eventually lead to posterior labral pathology, or to the posterior glenoid wear commonly seen with osteoarthritis.

The role of the tendon ECM in mechanotransduction: disruption and repair following overuse

Purpose: Tendon overuse injuries are prevalent conditions with limited therapeutic options to halt disease progression. The specialized extracellular matrix (ECM) both enables joint function and mediates mechanical signals to tendon cells, driving biological responses to exercise or injury. With overuse, tendon ECM composition and structure changes at multiple scales, disrupting mechanotransduction and resulting in inadequate repair and disease progression. This review highlights the multiscale ECM changes that occur with tendon overuse and corresponding effects on cell-matrix interactions and cellular response to load.Results: Different functional joint requirements and tendon types experience a wide range of loading profiles, creating varied downstream mechanical stimuli. Distinct ECM structure and mechanical properties within the fascicle matrix, interfascicle matrix, and enthesis and their varied disruption with overuse are considered. The pericellular matrix (PCM) comprising the microscale tendon cell environment has a unique composition that changes with overuse injury and exercise, suggesting an important role in mechanotransduction and promoting repair. Cell-matrix interactions are mediated by structures including cilia, integrins, connexins and cytoskeleton that signal downstream homeostasis, adaptation, or repair. ECM disruption with tendon overuse may cause altered mechanical loading and cell-matrix interactions, resulting in mechanobiological understimulation, apoptosis, and ineffective repair. Current interventions to promote repair of tendon overuse injuries including exercise, targeting cell signaling, and modulating inflammation are considered.Conclusion: Future therapeutics should be assessed with regard of their effects on multiscale mechanotransduction in addition to joint function, with consideration of the central role of ECM.

The natural history of greater trochanteric pain syndrome: an 11-year follow-up study

Background

Greater trochanteric pain syndrome (GTPS) is a musculoskeletal condition which can cause disability and reduce quality of life. However, limited evidence is available on the long-term outcomes of people with GTPS. Our aims were to determine the long-term prevalence of GTPS; to calculate the proportion of people with GTPS who had developed hip osteoarthritis (OA); and to determine the level of function and quality of life, 11-years after initial GTPS diagnosis.

Methods

A prospective 11-year natural history study. Two groups [GTPS group (n = 24), asymptomatic control (ASC) group (n = 20)] were evaluated at baseline, 12-months and 11-years. At 11-years all participants completed the modified Harris Hip Score (mHHS), Oswestry Disability Index (ODI) and Assessment of Quality-of-Life questionnaire. At 11-year follow-up 20/24 GTPS and 19/20 ASC participants were clinically assessed for GTPS and hip OA, completed the 10 metre-walk-test, timed up and go, and hip abduction and external rotation strength testing.

Results

At 11-year follow-up 45.0% of GTPS participants had GTPS compared to 5.3% of ASC participants (p = 0.008), OR [95% CI]: 10.19 [1.95, 104.3], and 35.0% of GTPS participants were clinically diagnosed with hip OA compared to none of the ASC participants (p = 0.002), OR [95% CI]: 21.6, [2.3, 2898.0]. GTPS participants reported more pain and disability than ASC participants via the ODI, mean difference [95% CI]: 6.1 [0.7, 11.6] but not the modified Harris Hip Score, mean difference [95% CI]: -3.3 [-10.3, 3.7]. Both groups had similar levels of quality of life and measures of function.

Conclusions

GTPS is a chronic condition: people with GTPS at baseline had twice the odds of being clinically diagnosed with GTPS or hip OA than the control group at 11-years. Further, there appears to be a temporal relationship between GTPS and the development of hip OA. This finding highlights the need to identify effective treatments that address the underlying impairments associated with GTPS. Pain and function results varied depending on the assessment tools used. Between group differences in quality of life seen at baseline are not found at the 11-year follow-up. The small sample size means the results must be considered with caution.

Level of Evidence

Level II Natural history Study.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04935-w.

When should reverse total shoulder arthroplasty be considered in glenohumeral joint arthritis?

Anatomical total shoulder arthroplasty (TSA) has been used widely in treatment of glenohumeral osteoarthritis and provides excellent pain relief and functional results. Reverse total shoulder arthroplasty (RSA) was created to treat the complex problem of rotator cuff tear arthropathy. RSA also has been performed for glenohumeral osteoarthritis even in cases where the rotator cuff is preserved and has shown good results comparable with TSA. The indications for RSA are expanding to include tumors of the proximal humerus, revision of hemiarthroplasty to RSA, and revision of failed TSA to RSA. The purposes of this article were to describe comprehensively the conditions under which RSA should be considered in glenohumeral osteoarthritis, to explain its theoretical background, and to review the literature.

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.

Histological and ultrastructural degenerative findings in the gluteus medius tendon after hip arthroplasty

Background

Despite gluteus medius (GMED) tendinosis being relatively common, its presence in association with hip osteoarthritis (OA) or total hip arthroplasty (THA) is not well studied. It was hypothesized that more tendon degeneration would be found in patients with OA of the hip and in those that had undergone THA than that in a control group.

Methods

One hundred patients were included between 2016 and 2019 and were included into 4 groups; the patients were undergoing revision surgery in two groups and primary THA in the other two groups; 22 patients had previously undergone primary THA through a direct lateral approach (involving sectioning of the GMED tendon), 24 patients had previously undergone primary THA through a posterior approach (leaving the GMED tendon intact), 29 patients had primary hip OA, and 25 patients who suffered a femoral neck fracture served as controls. Biopsies from the GMED tendon were obtained at the time of the primary THA or the hip revision surgery. The tendon biopsies were examined ultrastructurally and histologically.

Results

Ultrastructurally, the direct lateral and posterior revision groups had statistically significantly more collagen fibrils with smaller diameters compared with the fracture and primary THA groups. Moreover, the direct lateral revision group had more collagen fibrils with smaller diameters compared with the posterior revision group.

Histologically, the direct lateral revision group had a higher total degeneration score (TDS) compared with the primary hip OA group.

Conclusions

The GMED tendon shows more ultrastructural degeneration in patients who undergo hip revision arthroplasty than in patients with primary OA of the hip and control patients, who had suffered a femoral neck fracture. Furthermore, patients who had previously undergone primary THA through a direct lateral approach revealed more histological GMED tendon degeneration than patients who suffer primary hip OA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02434-1.

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

BACKGROUND

Untreated rotator cuff tears lead to irreversible tendon degeneration, resulting in unacceptable repair prognosis. The inability of current animal models of degenerated rotator cuff tendons to more fully emulate the manifestation and degree of pathology seen in humans with a previously torn rotator cuff tendon (s) significantly impairs the development of novel therapeutics. Therefore, the objective of this study was to develop a large-animal translational model of enthesis damage to the rotator cuff tendons to mimic the chronic degenerative changes that occur in patients that demonstrate clinical manifestations of tendinopathy.

METHODS

A partial enthesis tear model (i.e., sharp transection) in adult sheep was created by cutting the tendon fibers perpendicularly through the enthesis midpoint, while leaving the other portion of the tendon in-tact. To assess tendon integrity, non-destructive biomechanical tests were performed, followed by histopathological, histomorphological, and gene expression analysis. Samples of degenerated human rotator cuff tendons obtained from patients undergoing reverse total shoulder arthroplasty to use for comparative pathological analysis.

RESULTS

In the sheep model, transected tendons at all timepoints had significantly decreased mechanical properties. Histopathologic evaluation and Bonar scoring revealed that the tendons in sheep underwent degenerative changes similar in magnitude and manifestation as the degenerated human tendon samples. Furthermore, similar levels of collagen disorganization were noted between the 6 and 12-week ovine samples and the degenerated human samples.

CONCLUSIONS

These findings indicate that the new sheep model of rotator cuff injury reliably recapitulates the structural and cellular changes that occur clinically in humans with chronic rotator cuff tendon injuries and suggest that this new model is well suited to evaluation of new therapeutic interventions.

Quantitative T2 mapping of the glenohumeral joint cartilage in asymptomatic shoulders and shoulders with increasing severity of rotator cuff pathology

•

Glenohumeral cartilage T2 values were correlated to increasing rotator cuff pathology severity.

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Massive tear versus lesser injury differences were most evident in superior humeral cartilage.

•

Sagittal T2 mapping best captures superior humeral head cartilage change in massive tear patients.

Purpose

To examine the relationship between glenohumeral cartilage T2 mapping values and rotator cuff pathology.

Method

Fifty-nine subjects (age 48.2 ± 13.5 years, 15 asymptomatic volunteers and 10 tendinosis, 13 partial-thickness tear, 8 full-thickness tear, and 13 massive tear patients) underwent glenohumeral cartilage T2 mapping. The humeral head cartilage was segmented in the sagittal and coronal planes. The glenoid cartilage was segmented in the coronal plane. Group means for each region were calculated and compared between the groups.

Results

Massive tear group T2 values were significantly higher than the asymptomatic group values for the humeral head cartilage included in the sagittal (45 ± 7 versus 32 ± 4 ms, p <  .001) and coronal (44 ± 6 versus 38 ± 1 ms, p =  0.01) plane images. Mean T2 was also significantly higher for massive than full-thickness tears (45 ± 7 versus 38 ± 5 ms, p =  0.02), massive than partial-thickness tears (45 ± 7 versus 34 ± 4 ms, p <  0.001), and massive tears than tendinosis (45 ± 7 versus 35 ± 4 ms, p =  0.001) in the sagittal-images humeral head region and significantly higher for massive tears than asymptomatic shoulders (44 ± 6 versus 38 ± 1 ms, p =  0.01) in the coronal-images humeral head region.

Conclusion

Humeral head cartilage T2 values were significantly positively correlated with rotator cuff pathology severity. Massive rotator cuff tear patients demonstrated significantly higher superior humeral head cartilage T2 mapping values relative to subjects with no/lesser degrees of rotator cuff pathology.

No significant histological or ultrastructural tendinosis changes in the hamstring tendon in patients with mild to moderate osteoarthritis of the knee?

PURPOSE

To investigate the periarticular degenerative changes of the knee joint in association with osteoarthritis (OA). More tendinosis was expected to be found in the semitendinosus tendon in patients with knee OA than in patients without knee OA.

METHODS

Samples from 41 patients were included between January 2016 and October 2017. Twenty-one patients median age 53 (33-63) years with mild to moderate OA underwent high tibial osteotomy (HTO) and 20 patients median age 38 (31-57) years without OA underwent anterior cruciate ligament reconstruction (ACLR). Biopsies from the semitendinosus tendon were obtained at the time of surgery and examined histologically, morphologically and ultrastructurally using light and electron microscope.

RESULTS

The histological evaluation of the semitendinosus tendon revealed the presence of more hemosiderin in the ACLR group. No significant morphological or ultrastructural differences were shown between patients in the HTO and ACLR group.

CONCLUSION

Patients with mild and moderate medial compartment knee OA displayed no more degenerative changes in their semitendinosus tendon than patients without OA, as seen in both the light and the electron microscope.

LEVEL OF EVIDENCE

III.

Exosomes: roles and therapeutic potential in osteoarthritis

Exosomes participate in many physiological and pathological processes by regulating cell-cell communication, which are involved in numerous diseases, including osteoarthritis (OA). Exosomes are detectable in the human articular cavity and were observed to change with OA progression. Several joint cells, including chondrocytes, synovial fibroblasts, osteoblasts, and tenocytes, can produce and secrete exosomes that influence the biological effects of targeted cells. In addition, exosomes from stem cells can protect the OA joint from damage by promoting cartilage repair, inhibiting synovitis, and mediating subchondral bone remodeling. This review summarizes the roles and therapeutic potential of exosomes in OA and discusses the perspectives and challenges related to exosome-based treatment for OA patients in the future.

Risk Factors for Rotator Cuff Disease: An Experimental Study on Intact Human Subscapularis Tendons

Although several studies revealed a multifactorial pathogenesis of degenerative rotator cuff disorders, the impact and interaction of extrinsic variables is still poorly understood. Thus, this study aimed at uncovering the effect of patient- and pathology-specific risk factors that may contribute to degeneration of the rotator cuff tendons. Between 2015 and 2018, 54 patients who underwent arthroscopic shoulder surgery at three specialized shoulder clinics were prospectively included. Using tendon samples harvested from the macroscopically intact subscapularis (SSC) tendon, targeted messenger RNA expression profile analysis was performed in the first cohort (n = 38). Furthermore, histological analyses were conducted on tendon tissue samples obtained from a second cohort (n = 16). Overall, both study cohorts were comparable concerning patient demographics. Results were then analyzed with respect to specific extrinsic factors, such as patient age, body mass index, current as well as previous professions and sport activities, smoking habit, and systemic metabolic diseases. While patient age, sports-activity level, and preexisting rotator cuff lesions were considered to contribute most strongly to tendinopathogenesis, no further coherences were found. With regards to gene expression analysis, change in expression correlated most strongly with patient age and severity of the rotator cuff pathology. Further, chronic disorders increased overall gene expression variation. Taken together, our study provides further evidence that tendon degeneration is the consequence of a multifactorial process and pathological changes of the supraspinatus tendon affect the quality of SSC tendon and most likely vice versa. Therefore, the rotator cuff tendons need to be considered as a unit when managing rotator cuff pathologies. © 2019 The Authors. Journal of Orthopaedic Research^® published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society J Orthop Res 38:182-191, 2020.