Genetic influences in the progression of tears of the rotator cuff

Rotator cuff tears

Rotator cuff tears are the most common upper extremity condition seen by primary care and orthopaedic surgeons, with a spectrum ranging from tendinopathy to full-thickness tears with arthritic change. Some tears are traumatic, but most rotator cuff problems are degenerative. Not all tears are symptomatic and not all progress, and many patients in whom tears become more extensive do not experience symptom worsening. Hence, a standard algorithm for managing patients is challenging. The pathophysiology of rotator cuff tears is complex and encompasses an interplay between the tendon, bone and muscle. Rotator cuff tears begin as degenerative changes within the tendon, with matrix disorganization and inflammatory changes. Subsequently, tears progress to partial-thickness and then full-thickness tears. Muscle quality, as evidenced by the overall size of the muscle and intramuscular fatty infiltration, also influences symptoms, tear progression and the outcomes of surgery. Treatment depends primarily on symptoms, with non-operative management sufficient for most patients with rotator cuff problems. Modern arthroscopic repair techniques have improved recovery, but outcomes are still limited by a lack of understanding of how to improve tendon to bone healing in many patients.

Biological and Mechanical Factors and Epigenetic Regulation Involved in Tendon Healing

Tendons are an important part of the musculoskeletal system. Connecting muscles to bones, tendons convert force into movement. Tendon injury can be acute or chronic. Noticeably, tendon healing requires a long time span and includes inflammation, proliferation, and remodeling processes. The mismatch between endogenous and exogenous healing may lead to adhesion causing further negative effects. Management of tendon injuries and complications such as subsequent adhesion formation are still challenges for clinicians. Due to numerous factors, tendon healing is a complex process. This review introduces the role of various biological and mechanical factors and epigenetic regulation processes involved in tendon healing.

Ethnicity, sex, and socioeconomic disparities in the treatment of traumatic rotator cuff injuries in Aotearoa/New Zealand

HYPOTHESIS AND BACKGROUND

Traumatic rotator cuff injuries can be a leading cause of prolonged shoulder pain and disability and contribute to significant morbidity and health care costs. Previous studies have shown evidence of sociodemographic disparities with these injuries. The purpose of this nationwide study was to better understand these disparities based on ethnicity, sex, and socioeconomic status, in order to inform future health care strategies.

METHODS

Accident Compensation Corporation (ACC) is a no-fault comprehensive compensation scheme encompassing all of Aotearoa/New Zealand (population in 2018, 4.7 million). Using the ACC database, traumatic rotator cuff injuries were identified between January 2010 and December 2018. Injuries were categorized by sex, ethnicity, age, and socioeconomic deprivation index of the claimant.

RESULTS

During the 9-year study period, there were 351,554 claims accepted for traumatic rotator cuff injury, which totaled more than NZ$960 million. The greatest proportion of costs was spent on vocational support (49.8%), then surgery (26.3%), rehabilitation (13.1%), radiology (8.1%), general practitioner (1.6%), and "Other" (1.1%). Asian, Māori (indigenous New Zealanders), and Pacific peoples were under-represented in the age-standardized proportion of total claims and had lower rates of surgery than Europeans. Māori had higher proportion of costs spent on vocational support and lower proportions spent on radiology, rehabilitation, and surgery than Europeans. Males had higher number and costs of claims and were more likely to have surgery than females. There were considerably fewer claims from areas of high socioeconomic deprivation.

DISCUSSION AND CONCLUSION

This large nationwide study demonstrates the important and growing economic burden of rotator cuff injuries. Indirect costs, such as vocational supports, are a major contributor to the cost, suggesting improving treatment and rehabilitation protocols would have the greatest economic impact. This study has also identified sociodemographic disparities that need to be addressed in order to achieve equity in health outcomes.

Genetic Characterization in Familial Rotator Cuff Tear: An Exome Sequencing Study

Background: multiple gene variants seem to contribute to rotator cuff (RC) tear susceptibility. The aim of the study is to perform an exome sequencing analysis within a family to identify rare gene variants predisposing to the development of RC tear. Material and methods: the exome sequencing was conducted in a family consisting of four individuals, two healthy and the remaining ones with bilateral RC tears. Variants in common among the two affected subjects were selected, and those in common with the healthy subject and those with a frequency >1% were removed. The potential pathogenicity of the variants was investigated using the predictions of several in silico tools from VarSome. Results: the exome sequencing yielded approximately 600,000 variants per patient, subsequently filtered according to frequency <1% and absence of association with other diseases. Removing variants common with the healthy subject, 348 rare variants among 248 genes were identified. Based on the risk of damaging, three candidate genes for RC tear were found: COL23A1, EMILIN3, and HDAC10. Conclusion: this is the first whole-exome sequencing analysis within a family to explore genetic predisposition in RC tear. The results reveal the presence of common damaging variants among affected individuals in the COL23A1, EMILIN3, and HDAC10 genes.

The role of familial predisposition in imaging-confirmed atraumatic rotator cuff tears

BACKGROUND

The etiology of atraumatic rotator cuff tears is not completely understood. Limited data suggest the role of genetic and familial predisposition in the etiology of rotator cuff tears. The purpose of this study was to assess whether there is an increased likelihood of rotator cuff tears in family members of patients with rotator cuff tears vs. those without tears. This would provide evidence for whether there is an association between familial predisposition and rotator cuff tearing.

METHODS

Patients presenting to a shoulder clinic were recruited in this study. They provided information on personal medical history, shoulder symptoms, and family history of rotator cuff tears. The diagnosis of rotator cuff tears was based on imaging (magnetic resonance imaging or computed tomography arthrogram) confirmation of a structural defect in the rotator cuff. The association between family history of rotator cuff problems and the likelihood of an imaging-confirmed rotator cuff tear diagnosis was evaluated using multivariate logistic regression, adjusting for age, sex, race/ethnicity, cigarette smoking, hypertension, diabetes, and depression.

RESULTS

In our cohort of 2335 patients, 52.6% (n = 1229) of patients had a rotator cuff tear. Among patients with tears, 17.9% (n = 220) of patients reported a family history of rotator cuff issues vs. 11.1% (n = 123) in patients without tears. A family history of rotator cuff problems was significantly associated with the diagnosis of an imaging-confirmed rotator cuff tear (odds ratio [OR] 2.24, 95% confidence interval [CI] 1.71, 2.95). Other confounding variables such as increasing age (OR 1.06, 95% CI 1.05, 1.07) and Hispanic race/ethnicity as compared to non-Hispanic white race/ethnicity (OR 1.48, 95% CI 1.07, 2.05) were significantly associated with rotator cuff tears. Sex, smoking, hypertension, diabetes, and depression were not significantly associated with rotator cuff tearing.

CONCLUSION

Our study shows that individuals with rotator cuff tears were more than 2 times as likely to have a family member with a tear as compared to patients without tears. Increasing age and patients who identified as being of Hispanic ancestry were also significantly associated with higher odds of rotator cuff tears.

The role of MicroRNAs in tendon injury, repair, and related tissue engineering

Tendon injuries are one of the most common musculoskeletal disorders that cause considerable morbidity and significantly compromise the patients' quality of life. The innate limited regenerative capacity of tendon poses a substantial treating challenge for clinicians. MicroRNAs (miRNAs) are a family of small non-coding RNAs that play a vital role in orchestrating many biological processes through post-transcriptional regulation. Increasing evidence reveals that miRNA-based therapeutics may serve as an innovative strategy for the treatment of tendon pathologies. In this review, we briefly present miRNA biogenesis, the role of miRNAs in tendon cell biology and their involvement in tendon injuries, followed by a summary of current miRNA-based approaches in tendon tissue engineering with a special focus on attenuating post-injury fibrosis. Next, we discuss the advantages of miRNA-functionalized scaffolds in achieving sustained and localized miRNA administration to minimize off-target effects, and thus hoping to inspire the development of effective miRNA delivery platforms specifically for tendon tissue engineering. We envision that advancement in miRNA-based therapeutics will herald a new era of tendon tissue engineering and pave a way for clinical translation for the treatments of tendon disorders.

Association between type of rotator cuff tear and functional outcomes in patients with massive and irreparable rotator cuff tear: A pre-post intervention study

BACKGROUND

The aim of this study was to analyze: (1) the differences in the pre-post change in functional outcomes after a physical therapy program by the type of massive and irreparable rotator cuff tear (MIRCT) controlling for potential confounders, and (2) the influence of lifestyle behaviors and demographic and tear tendon characteristics on function in patients over 60 years of age with conservatively treated MIRCT.

MATERIALS AND METHODS

In this pre-post intervention study, 92 patients were prospectively recruited at the Clinical Hospital San Borja Arriaran, with atraumatic MIRCT, between 60 and 75 years of age (mean: 67.9 ± 4.5 years), and the mean of length of symptoms was 16.5 months (±5.7 months). Patients received a physical therapy program consisting of manual therapy and a specific exercise program of 2 sessions per week for 12 weeks. The imaging findings were performed by 2 medical radiologists who classified the rotator cuff tear according to the criteria proposed by Collins. Shoulder function, upper limb function, and pain intensity were assessed with the Constant-Murley; Disabilities of the Arm, Shoulder, and Hand; and visual analog scale (VAS), respectively. Analysis of covariance models were estimated to assess differences in MIRCT categories between functional outcomes. Multiple regression model analysis was used for the association between the change in functional outcomes and lifestyle behaviors, and demographic and tear tendon characteristics.

RESULTS

The results showed no pre-post change in functional outcomes by type of MIRCT in all models (P > .05). There is an association between length of symptoms (P = .000), and the baseline values of the 3 functional measures (P = .000) are associated with changes in Constant-Murley; Disabilities of the Arm, Shoulder, and Hand; and VAS. In addition, changes in VAS are associated with body mass index (BMI) (P = .000), and changes in Constant-Murley are associated with gender (P = .023), BMI (P = .000), and tobacco consumption (P = .000).

CONCLUSION

There is no difference in functional outcomes by type of MIRCT after a physical therapy program controlling for potential confounders. In addition, there is an association of length of symptoms with all functional outcomes, an association of BMI with VAS and Constant-Murley questionnaire, and an association between tobacco consumption and Constant-Murley questionnaire. Our results could influence the orthopedic surgeon's decisions; thus, not predicting the functional outcome through imaging findings could lead clinicians to reconsider the need for surgery in the treatment algorithm in patients over 60 years with MIRCT. In addition, demographic characteristics and lifestyle behaviors might be considered within the patient's evaluation and follow-up to decide on surgical interventions and evaluate the clinical course of the disease. Further studies measuring additional variables and longer follow-up are needed to confirm these results.

Genetic Aspects in Shoulder Disorders

The influence of genetic inheritance has been increasingly investigated in shoulder disorders, such as rotator cuff injury, instability and frozen shoulder. Although the initial findings are enlightening, it is necessary to progressively build a database of genetic markers to catalog genomic profiles that, later, may contribute for predicting the risk of the disease, as well as to the development of better diagnostic and treatment tools. The present article seeks to update what is evidence of genetic studies in the literature for these diseases, from polymorphism analyses, expression of candidate genes in tissues and broad genomic association studies (GWAS). However, it is necessary to point out that there is great difficulty in replicating and using the findings, mainly due to the lack of statistical power, the high rate of false-positive results and the large number of variables involved.

SAP30BP gene is associated with the susceptibility of rotator cuff tear: a case-control study based on Han Chinese population

Background

Multiple studies have indicated that genetic components contribute significantly to the risk of rotator cuff tears. Previous studies have suggested that the SAP30BP gene may play an essential role in the development of rotator cuff tears. The aim of this study was to evaluate the potential association of the SAP30BP gene with the susceptibility to rotator cuff tears in a Han Chinese population.

Methods

A total of 394 patients with rotator cuff tears and 998 healthy controls were included in the study. Twelve tag single nucleotide polymorphisms (SNPs) located in the region of the SAP30BP gene were selected for genotyping. Genetic association analyses were performed using χ² tests for each SNP. Significant associations were searched in the GTEx database for their functional consequences.

Results

SNP rs820218 was significantly associated with rotator cuff tears (χ² = 9.49, P = 0.0021, OR [95% CI] = 0.67 [0.52–0.87]). In addition, SNP rs820218 was found to be significantly associated with the gene expression level of SAP30BP in whole blood (NES = 0.12, P = 1.00 × 10⁻⁶).

Conclusion

Our study has shown that the genetic polymorphism of SAP30BP contributes to the risk of rotator cuff tears in Chinese Han people. Individuals with the A allele for SNP rs820218 were less susceptible to developing rotator cuff tears.

Genetic basis of rotator cuff injury: a systematic review

Background

Rotator cuff disease is a widespread musculoskeletal pathology and a major cause of shoulder pain. Studies on familial predisposition suggest that genetic plays a role in the pathogenesis of rotator cuff disease. Several genes are responsible for rotator cuff disease. The aim of this study was to perform a systematic review on genetic association between rotator cuff disease and genes variations.

Methods

A systematic review of the literature was performed, in accordance with the PRISMA guidelines. PubMed, Medline, CINAHL, Cochrane, Embase and Google Scholar databases were searched comprehensively using the keywords: “Rotator cuff”, “Gene”, “Genetic”, “Predisposition”, “Single-nucleotide polymorphism” and “Genome-wide association”.

Results

8 studies investigating genes variations associated with rotator cuff tears were included in this review. 6 studies were case-control studies on candidate genes and 2 studies were GWASs. A significant association between SNPs and rotator cuff disease was found for DEFB1, FGFR1, FGFR3, ESRRB, FGF10, MMP-1, TNC, FCRL3, SASH1, SAP30BP, rs71404070 located next to cadherin8. Contradictory results were reported for MMP-3.

Conclusion

Further investigations are warranted to identify complete genetic profiles of rotator cuff disease and to clarify the complex interaction between genes, encoded proteins and environment. This may lead to individualized strategies for prevention and treatment of rotator cuff disease.

Level of evidence

Level IV, Systematic Review.

Rotator Cuff Degeneration: The Role of Genetics

BACKGROUND

The literature is certain regarding the multifactorial etiology of rotator cuff degeneration. However, it remains unclear if rotator cuff degeneration exclusively depends on intrinsic and extrinsic factors or if it is also genetically determined. We compared the health status of cuff tendons, evaluated with a magnetic resonance imaging (MRI) study, between elderly monozygotic and dizygotic twins with the aim of separating the contributions of genetics from shared and unique environments.

METHODS

The rotator cuff tendon status was assessed using the Sugaya classification by MRI. Heritability, defined as the proportion of total variance of a specific characteristic in a particular population due to a genetic cause, was calculated as twice the difference between the intraclass correlation coefficients for monozygotic and dizygotic pairs. The influence of shared environment, which contributes to twin and sibling similarity, was calculated as the difference between the monozygotic correlation coefficient and the heritability index.

RESULTS

We identified 33 pairs of elderly twins: 17 monozygotic pairs and 16 dizygotic pairs, with a mean age (and standard deviation) of 64.62 ± 3.32 years. The polychoric correlation was 0.62 in monozygotic twins and 0.53 in dizygotic twins. The calculated heritability index was 0.18 (18%), and the contribution was 0.44 (44%) for the shared environment and 0.38 (38%) for the unique environment.

CONCLUSIONS

The role of genetics in rotator cuff degeneration is quantified by our study on elderly monozygotic and dizygotic twins; however, it is only partial with respect to the contribution of shared and unique environments.

Recovery of Range of Motion and Decrease in Pain after Progression of Supraspinatus Tendon Tear: A Case Report

Rotator cuff disease is one of the most prevalent shoulder disabilities especially in the elderly population. Tear progression is significantly greater in the symptomatic patients than in the asymptomatic ones. From these aspects, shoulder surgeons interpret surgical indications and counsel patients regarding the risk of non-operative treatments. However, there were a few reports that pain and duration of symptoms were not strongly associated with severity of rotator cuff tears, and non-operative management with physical therapy was effective. There have remained controversies for the treatment of rotator cuff tears.

A 59-year-old man with a sedentary work life experienced right shoulder pain with abduction at night. However, the pain kept worsening after two months, and he finally visited our clinic three months after the onset of pain. Magnetic resonance imaging in the coronal and axial planes showed effusion around the subacromial and subcoracoid bursae and joint-side tear of the supraspinatus tendon. A range of motion in the right shoulder was severely restricted at the initial visit of our clinic. After sufficient rehabilitation, the symptoms were not changed and an arthroscopic rotator cuff repair was scheduled. However, during waiting for surgery, he felt something popped in the right shoulder while wearing a jacket. Immediately after this, pain during motion and at night decreased, and he experienced no difficulty with activities of daily living and the surgery was cancelled. This is the first case with a recovery of range of motion and a decrease in pain after progression of a supraspinatus tendon tear.

Genetics of rotator cuff tears: no association of col5a1 gene in a case-control study

Background

The incidence of RC tears increases with aging, affecting approximately 30 to 50% of individuals older than 50 years, and more than 50% of individuals older than 80 years. Intrinsic factors (age or gender), extrinsic factors (sports activity or occupation), and biological factors were identified in the onset and progression of RC tears. The attention in the study of aetiology of RC tendinopathy has shifted to the identification of gene variants. Genes encoding for proteins regulating the concentration of pyrophosphate in the extracellular matrix and genes encoding for fibroblastic growth factors, defensin beta 1 and estrogen-related receptor-beta were analyzed. However, only in one study the role of variants of collagen type V alpha 1 (col5a1) gene in RC tears was assessed. The objective of this study was to determine whether a col5a1 DNA sequence variant, rs12722 (C/T) was associated with rotator cuff (RC) tears in a case-control study.

Methods

The study included 93 Caucasian patients undergoing surgery for RC tears and 206 patients with no history and sign of RC disease as evaluated by MRI. Patients were divided into two groups. Group 1 included patients with RC tear diagnosed on clinical and imaging grounds and confirmed at the time of surgery. Group 2 (control group) included patients without history or clinical symptoms of RC disorders and with a MRI negative for RC disease. DNA was obtained from approximately 1.2 ml of venous blood using the MagCore extractor system H16 with a MagCore Genomic DNA Large Volume Whole Blood Kit (RBC Bioscience Corp., Taiwan). All study participants were genotyped for SNPs rs12722.

Results

We first estimated that our study had 92% power at p < 0.05 to detect a genetic effect size of 2.05 in the RT tears (93 individuals) and healthy population (206 individuals) cohorts, assuming a minor allele frequency for col5a1 variant rs12722 of 0.5707 in the Italian population (gnomAD frequency). No significant difference in allele and genotype frequencies was observed between RT tears patients and healthy controls. Similarly, no significant association was seen between the RT tears and healthy controls participants in the combined genotype distributions.

Conclusion

In conclusion, no correlations between the SNP rs12722 of col5a1 gene and RC tears susceptibility was found.

Patients with a long-standing cuff tear in one shoulder have high rates of contralateral cuff tears: a study of patients with arthroscopically verified cuff tears 22 years ago

BACKGROUND

The prevalence of contralateral full-thickness cuff tears (FTTs) and cuff tear arthropathy (CTA) is presumed to be higher in patients with long-standing cuff tears than in those with newly diagnosed tears, but data are currently lacking.

METHODS

Sixty-one patients with 38 partial and 23 full-thickness tears of 1 shoulder at arthroscopy were examined with bilateral radiographs, ultrasound, and the Constant-Murley score at a mean of 22 years (range, 21-25 years) after arthroscopy.

RESULTS

The overall rate of full-thickness tears in the contralateral shoulder was 50.8%. In patients with a full-thickness tear and CTA (Hamada grade ≥2) in the index shoulder at follow-up, 18 of 20 (90%) had a contralateral full-thickness tear and 4 of 20 (20%) had CTA. In patients with a partial tear in the index shoulder at follow-up, 3 of 22 (13.6%) had a contralateral full-thickness tear and none had CTA. CTA changes were more common in patients with FTT and a previous acromioplasty (P < .001). The correlation between shoulders was 0.72 for the number of tendons with FTT (P <.001), 0.31 for the Hamada grade (P = .016), and 0.65 for the absolute Constant-Murley score (P <.001). The number of tendons with a full-thickness tear at follow-up was a risk factor (odds ratio, 3.28; 95% confidence interval, 1.67-6.44; P <.001) for a contralateral full-thickness tear. Patients with a partial or full-thickness tear in the contralateral shoulder had pain in 39.2% of cases.

CONCLUSION

Patients with long-standing cuff tears have high rates of contralateral cuff tears. The severity of the condition is strongly correlated between the shoulders. Patients with full-thickness tears and a previous acromioplasty have a significantly higher frequency of CTA than patients with cuff tears who had not undergone a previous acromioplasty.

The potential role of angiogenesis in the development of shoulder pain, shoulder dysfunction, and lymphedema after breast cancer treatment

Shoulder morbidity is a well-documented sequela of breast cancer treatment, which includes various manifestations such as pain, reduced range of motion, and lymphedema, among others. The multifactorial nature of such morbidities has long been appreciated, and research on reliable risk predictors of development thereof still continues. Previous studies have demonstrated the potential of different types of physical therapy to treat such shoulder problems, and the integration of such interventions into routine care for breast cancer survivors is a requirement in most high-income countries. Although patients at risk for developing shoulder problems would most likely benefit from posttreatment physical therapy, currently, there is no gold standard for identifying this patient group. This is particularly important in low- and middle-income countries where scarce monetary resources need to be directed specifically to those most in need. Modulators of the angiogenesis pathway have been implicated in noncancer shoulder conditions such as rotator cuff disease, adhesive capsulitis, and tendon injuries. The present review summarizes the role of angiogenesis in the development of shoulder morbidity among breast cancer survivors and sets forth the rationale for our belief that angiogenesis signaling may help explain a proportion of the reported clinical variability noted in the development of shoulder pain and dysfunction and upper-limb lymphedema after breast cancer treatment.

Genome-wide association study identifies a locus associated with rotator cuff injury

Rotator cuff tears are common, especially in the fifth and sixth decades of life, but can also occur in the competitive athlete. Genetic differences may contribute to overall injury risk. Identifying genetic loci associated with rotator cuff injury could shed light on the etiology of this injury. We performed a genome-wide association screen using publically available data from the Research Program in Genes, Environment and Health including 8,357 cases of rotator cuff injury and 94,622 controls. We found rs71404070 to show a genome-wide significant association with rotator cuff injury with p = 2.31x10-8 and an odds ratio of 1.25 per allele. This SNP is located next to cadherin8, which encodes a protein involved in cell adhesion. We also attempted to validate previous gene association studies that had reported a total of 18 SNPs showing a significant association with rotator cuff injury. However, none of the 18 SNPs were validated in our dataset. rs71404070 may be informative in explaining why some individuals are more susceptible to rotator cuff injury than others.

Chronic inflammation is a feature of Achilles tendinopathy and rupture

Background

Recent investigation of human tissue and cells from positional tendons such as the rotator cuff has clarified the importance of inflammation in the development and progression of tendon disease. These mechanisms remain poorly understood in disease of energy-storing tendons such as the Achilles. Using tissue biopsies from patients, we investigated if inflammation is a feature of Achilles tendinopathy and rupture.

Methods

We studied Achilles tendon biopsies from symptomatic patients with either mid-portion tendinopathy or rupture for evidence of abnormal inflammatory signatures. Tendon-derived stromal cells from healthy hamstring and diseased Achilles were cultured to determine the effects of cytokine treatment on expression of inflammatory markers.

Results

Tendinopathic and ruptured Achilles highly expressed CD14+ and CD68+ cells and showed a complex inflammation signature, involving NF-κB, interferon and STAT-6 activation pathways. Interferon markers IRF1 and IRF5 were highly expressed in tendinopathic samples. Achilles ruptures showed increased PTGS2 and interleukin-8 expression. Tendinopathic and ruptured Achilles tissues expressed stromal fibroblast activation markers podoplanin and CD106. Tendon cells isolated from diseased Achilles showed increased expression of pro-inflammatory and stromal fibroblast activation markers after cytokine stimulation compared with healthy hamstring tendon cells.

Conclusions

Tissue and cells derived from tendinopathic and ruptured Achilles tendons show evidence of chronic (non-resolving) inflammation. The energy-storing Achilles shares common cellular and molecular inflammatory mechanisms with functionally distinct rotator cuff positional tendons. Differences seen in the profile of ruptured Achilles are likely to be attributable to a superimposed phase of acute inflammation and neo-vascularisation. Strategies that target chronic inflammation are of potential therapeutic benefit for patients with Achilles tendon disease.

Increased 15-PGDH expression leads to dysregulated resolution responses in stromal cells from patients with chronic tendinopathy

The mechanisms underpinning the failure of inflammation to resolve in diseased musculoskeletal soft tissues are unknown. Herein, we studied bioactive lipid mediator (LM) profiles of tendon-derived stromal cells isolated from healthy donors and patients with chronic tendinopathy. Interleukin(IL)-1β treatment markedly induced prostaglandin biosynthesis in diseased compared to healthy tendon cells, and up regulated the formation of several pro-resolving mediators including 15-epi-LXA₄ and MaR1. Incubation of IL-1β stimulated healthy tendon cells with 15-epi-LXA₄ or MaR1 down-regulated PGE₂ and PGD₂ production. When these mediators were incubated with diseased cells, we only found a modest down regulation in prostanoid concentrations, whereas it led to significant decreases in IL-6 and Podoplanin expression. In diseased tendon cells, we also found increased 15-Prostaglandin Dehydrogenase (15-PGDH) expression as well as increased concentrations of both 15-epi-LXA₄ and MaR1 further metabolites, 15-oxo-LXA₄ and 14-oxo-MaR1. Inhibition of 15-PGDH using either indomethacin or SW033291 significantly reduced the further conversion of 15-epi-LXA₄ and MaR1 and regulated expression of IL-6, PDPN and STAT-1. Taken together these results suggest that chronic inflammation in musculoskeletal soft tissues may result from dysregulated LM-SPM production, and that inhibition of 15-PGDH activity together with promoting resolution using SPM represents a novel therapeutic strategy to resolve chronic tendon inflammation.

Genetic and familial predisposition to rotator cuff disease: a systematic review

BACKGROUND

Rotator cuff disease is a common disorder leading to shoulder pain and loss of function. Its etiology in atraumatic cases is uncertain and is likely to extend beyond repetitive microtrauma or overuse. Our objective was to determine whether there is a genetic or familial predisposition to rotator cuff disease.

METHODS

A literature search of PubMed and Embase databases identified 251 citations. After review of the titles, abstracts, and full articles, 7 met our inclusion and exclusion criteria.

RESULTS

Four studies assessed familial predisposition to rotator cuff disease. One of these demonstrated that siblings of an individual with a rotator cuff tear were more likely to develop a full-thickness tear and more likely to be symptomatic. A 5-year follow-up showed that the relative risks were increased for the siblings to have a full-thickness tear, for a tear to progress in size, and for being symptomatic. Another study demonstrated that a significantly higher number of individuals with tears had family members with a history of tears or surgery than those without tears did. The other 3 studies investigated whether a genetic predisposition to rotator cuff disease exists and found significant association of haplotypes in DEFB1, FGFR1, FGF3, ESRRB, and FGF10 and 2 single-nucleotide polymorphisms within SAP30BP and SASH1.

CONCLUSION

Prior studies provide preliminary evidence for genetic and familial predisposition to rotator cuff disease. However, there is a lack of large genome-wide studies that can provide more definitive information and guide early detection of individuals at risk, prophylactic rehabilitation, and potential gene therapies and regenerative medicine interventions.

Persistent stromal fibroblast activation is present in chronic tendinopathy

Background

Growing evidence supports a key role for inflammation in the onset and progression of tendinopathy. However, the effect of the inflammatory infiltrate on tendon cells is poorly understood.

Methods

We investigated stromal fibroblast activation signatures in tissues and cells from patients with tendinopathy. Diseased tendons were collected from well-phenotyped patient cohorts with supraspinatus tendinopathy before and after sub-acromial decompression treatment. Healthy tendons were collected from patients undergoing shoulder stabilisation or anterior cruciate ligament repair. Stromal fibroblast activation markers including podoplanin (PDPN), CD106 (VCAM-1) and CD248 were investigated by immunostaining, flow cytometry and RT-qPCR.

Results

PDPN, CD248 and CD106 were increased in diseased compared to healthy tendon tissues. This stromal fibroblast activation signature persisted in tendon biopsies in patients at 2–4 years post treatment. PDPN, CD248 and CD106 were increased in diseased compared to healthy tendon cells. IL-1β treatment induced PDPN and CD106 but not CD248. IL-1β treatment induced NF-κB target genes in healthy cells, which gradually declined following replacement with cytokine-free medium, whilst PDPN and CD106 remained above pre-stimulated levels. IL-1β-treated diseased cells had more profound induction of PDPN and CD106 and sustained expression of IL6 and IL8 mRNA compared to IL-1β-treated healthy cells.

Conclusions

We conclude that stromal fibroblast activation markers are increased and persist in diseased compared to healthy tendon tissues and cells. Diseased tendon cells have distinct stromal fibroblast populations. IL-1β treatment induced persistent stromal fibroblast activation which was more profound in diseased cells. Persistent stromal fibroblast activation may be implicated in the development of chronic inflammation and recurrent tendinopathy. Targeting this stromal fibroblast activation signature is a potential therapeutic strategy.

Inflammation activation and resolution in human tendon disease

Improved understanding of the role of inflammation in tendon disease is required to facilitate therapeutic target discovery. We studied supraspinatus tendons from patients experiencing pain before and after surgical subacromial decompression treatment. Tendons were classified as having early, intermediate, or advanced disease, and inflammation was characterized through activation of pathways mediated by interferon (IFN), nuclear factor κB (NF-κB), glucocorticoid receptor, and signal transducer and activator of transcription 6 (STAT-6). Inflammation signatures revealed expression of genes and proteins induced by IFN and NF-κB in early-stage disease and genes and proteins induced by STAT-6 and glucocorticoid receptor activation in advanced-stage disease. The proresolving proteins FPR2/ALX and ChemR23 were increased in early-stage disease compared to intermediate- to advanced-stage disease. Patients who were pain-free after treatment had tendons with increased expression of CD206 and ALOX15 mRNA compared to tendons from patients who continued to experience pain after treatment, suggesting that these genes and their pathways may moderate tendon pain. Stromal cells from diseased tendons cultured in vitro showed increased expression of NF-κB and IFN target genes after treatment with lipopolysaccharide or IFNγ compared to stromal cells derived from healthy tendons. We identified 15-epi lipoxin A4, a stable lipoxin isoform derived from aspirin treatment, as potentially beneficial in the resolution of tendon inflammation.

The Incidence of Subsequent Surgery After Outpatient Arthroscopic Rotator Cuff Repair

PURPOSE

To quantify the incidence and risk factors associated with subsequent shoulder procedures in individuals undergoing outpatient arthroscopic rotator cuff repair (ARCR).

METHODS

We examined the New York Statewide Planning and Research Cooperative Systems outpatient database from 2003 through 2014 to identify patients undergoing isolated ARCR with or without concomitant acromioplasty. Patients were longitudinally followed up for a minimum of 2 years to determine the incidence of subsequent ipsilateral shoulder surgery. The impact of age, sex, insurance, concomitant acromioplasty, and tobacco use on reoperation was explored.

RESULTS

Between 2003 and 2012, 30,430 patients underwent isolated ARCR. The mean age was 56.6 ± 11.5 years, and 55.1% were male patients. A total of 1,826 patients (6.0%) underwent subsequent ipsilateral outpatient shoulder surgery a mean of 24.3 ± 27.1 months after the initial ARCR. Of patients who underwent repeat surgery, 57.3% underwent a revision cuff repair. Patients who underwent additional outpatient shoulder surgery were significantly younger (53.7 ± 10.9 years v 56.8 ± 11.5 years, P < .001). Tobacco use was associated with an increased rate of subsequent surgery (7.3% v 5.9%, P = .044) and accelerated time to reoperation (16.9 months v 24.7 months, P < .001). Independent risk factors for subsequent ipsilateral surgery after initial ARCR were presence of a Workers' Compensation claim (odds ratio, 2.11; 95% confidence interval, 1.89-2.36; P < .001) and initial ARCR without acromioplasty (odds ratio, 1.20; 95% confidence interval, 1.09-1.34; P < .001).

CONCLUSIONS

We identified a 6.0% incidence of repeat ipsilateral surgery after isolated ARCR. Although reasons for reoperation are likely multifactorial, younger age, Workers' Compensation claim, and absence of acromioplasty at the time of initial ARCR remained independent predictors of subsequent outpatient procedures, whereas a history of tobacco use was associated with accelerated time to subsequent surgery.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Risk Factors, Pathobiomechanics and Physical Examination of Rotator Cuff Tears

Background:

It is important to appreciate the risk factors for the development of rotator cuff tears and specific physical examination maneuvers.

Methods:

A selective literature search was performed.

Results:

Numerous well-designed studies have demonstrated that common risk factors include age, occupation, and anatomic considerations such as the critical shoulder angle. Recently, research has also reported a genetic component as well. The rotator cuff axially compresses the humeral head in the glenohumeral joint and provides rotational motion and abduction. Forces are grouped into coronal and axial force couples. Rotator cuff tears are thought to occur when the force couples become imbalanced.

Conclusion:

Physical examination is essential to determining whether a patient has an anterosuperior or posterosuperior tear. Diagnostic accuracy increases when combining a series of examination maneuvers.

Identification of a genetic variant associated with rotator cuff repair healing

BACKGROUND

A familial and genetic predisposition for the development of rotator cuff tearing has been identified. The purpose of this study was to determine if a familial predisposition exists for healing after rotator cuff repair and if the reported significant association with a single-nucleotide polymorphism (SNP) in the ESRRB gene is present in patients who fail to heal.

MATERIALS AND METHODS

The study recruited 72 patients undergoing arthroscopic rotator cuff repair for a full-thickness posterosuperior tear. Magnetic resonance imaging studies were performed at a minimum of 1 year postoperatively (average, 2.6 years). Healing failures were classified as lateral or medial. Self-reported family history of rotator cuff tearing data and genome-wide genotypes were available. Characteristics of cases with and without a family history of rotator cuff tearing were compared, and a comparison of the frequency of SNP 1758384 (in ESRRB) was performed between patients who healed and those who failed to heal.

RESULTS

Of the rotator cuff repairs, 42% failed to heal; 42% of patients reported a family history of rotator cuff tear. Multivariate regression analysis showed a significant association between familiality and overall healing failure (medial and lateral failures) (P = .036) and lateral failures independently (P = .006). An increased risk for the presence of a rare allele for SNP rs17583842 was present in lateral failures compared with those that healed (P = .005).

CONCLUSIONS

Individuals with a family history of rotator cuff tearing were more likely to have repair failures. Significant association of a SNP variant in the ESRRB gene was also observed with lateral failure.

Rotator cuff tears: Review of epidemiology, clinical assessment and operative treatment

Rotator cuff tears (RTCs) are the most common cause of shoulder disability. There has been a proportional increase in the prevalence of RCT in accordance with the rising trend of an ageing population. In this article we review the current literature encompassing RCT epidemiology, risk factors and aetiopathogenesis. We also summarize the current diagnostic modalities, treatment options, rehabilitation and outcomes.

Utility of features of the patient's history in the diagnosis of atraumatic shoulder pain: a systematic review

BACKGROUND

Whereas physical examination tests for shoulder disorders have numeric values that describe the utility of the test and its effect on the probability of having a diagnosis, this information is lacking for elements of the history. The purpose of this study was to conduct a systematic review of the literature to determine numeric data (sensitivity, specificity, predictive values, and likelihood or odds ratios) for elements of the history with regard to diagnoses in patients with chronic atraumatic shoulder pain.

METHODS

We performed a systematic review to extract information from the existing literature regarding the numeric utility of different features of the patient history as they pertain to chronic atraumatic shoulder pain. Data sources were MEDLINE through PubMed (1946-January 2012) and EMBASE through Ovid (1980-January 2012).

RESULTS

Twenty-one studies met inclusion criteria. A diagnosis of rotator cuff tear was more likely with a history of hypercholesterolemia, having a relative with rotator cuff disease, excessive lifting, above-shoulder work, hand-held vibration work, or age older than 60 years. Acromioclavicular arthritis was more likely in weightlifters. Glenohumeral arthritis was more likely if the patient has a history of prior dislocation, age >75 years, or a diagnosis of knee osteoarthritis. Adhesive capsulitis was more likely with a history of diabetes or thyroid disorder. Posterior labral tear was more likely in football players.

CONCLUSIONS

The numeric values for the utility of these history features will help establish numeric probabilities for diagnoses in patients with shoulder pain.

Genome-wide association study for rotator cuff tears identifies two significant single-nucleotide polymorphisms

BACKGROUND

The precise etiology of rotator cuff disease is unknown, but prior evidence suggests a role for genetic factors. Limited data exist identifying specific genes associated with rotator cuff tearing. The purpose of this study was to identify specific genes or genetic variants associated with rotator cuff tearing by a genome-wide association study with an independent set of rotator cuff tear cases.

MATERIALS AND METHODS

A set of 311 full-thickness rotator cuff tear cases genotyped on the Illumina 5M single-nucleotide polymorphism (SNP) platform were used in a genome-wide association study with 2641 genetically matched white population controls available from the Illumina iControls database. Tests of association were performed with GEMMA software at 257,558 SNPs that compose the intersection of Illumina SNP platforms and that passed general quality control metrics. SNPs were considered significant if P < 1.94 × 10(-7) (Bonferroni correction: 0.05/257,558).

RESULTS

Tests of association revealed 2 significantly associated SNPs, one occurring in SAP30BP (rs820218; P = 3.8E-9) on chromosome 17q25 and another occurring in SASH1 (rs12527089; P = 1.9E-7) on chromosome 6q24.

CONCLUSIONS

This study represents the first attempt to identify genetic factors influencing rotator cuff tearing by a genome-wide association study using a dense/complete set of SNPs. Two SNPs were significantly associated with rotator cuff tearing, residing in SAP30BP on chromosome 17 and SASH1 on chromosome 6. Both genes are associated with the cellular process of apoptosis. Identification of potential genes or genetic variants associated with rotator cuff tearing may help in identifying individuals at risk for the development of rotator cuff tearing.

Assessment and treatment strategies for rotator cuff tears

Tears of the rotator cuff are common and becoming an increasingly frequent problem. There is a vast amount of literature on the merits and limitations of the various methods of clinical and radiological assessment of rotator cuff tears. This is also the case with regard to treatment strategies. Certain popular beliefs and principles practiced widely and the basis upon which they are derived may be prone to inaccuracy. We provide an overview of the historical management of rotator cuff tears, as well as an explanation for how and why rotator cuff tears should be managed, and propose a structured methodology for their assessment and treatment.

Natural History of Rotator Cuff Disease and Implications on Management

Degenerative rotator cuff disease is commonly associated with ageing and is often asymptomatic. The factors related to tear progression and pain development are just now being defined through longitudinal natural history studies. The majority of studies that follow conservatively treated painful cuff tears or asymptomatic tears that are monitored at regular intervals show slow progression of tear enlargement and muscle degeneration over time. These studies have highlighted greater risks for disease progression for certain variables, such as the presence of a full-thickness tear and involvement of the anterior aspect supraspinatus tendon. Coupling the knowledge of the natural history of degenerative cuff tear progression with variables associated with greater likelihood of successful tendon healing following surgery will allow better refinement of surgical indications for rotator cuff disease. In addition, natural history studies may better define the risks of nonoperative treatment over time. This article will review pertinent literature regarding degenerative rotator cuff disease with emphasis on variables important to defining appropriate initial treatments and refining surgical indications.

Significant association of full-thickness rotator cuff tears and estrogen-related receptor-β (ESRRB)

BACKGROUND

The precise etiology of rotator cuff disease is unknown, but prior evidence suggests a role for genetic factors. Variants of estrogen-related receptor-β (ESRRB) have been previously associated with rotator cuff disease. The purpose of the present study was to confirm the association between multiple candidate genes, including ESRRB, and rotator cuff disease in an independent set of patients with rotator cuff tear.

MATERIALS AND METHODS

The Illumina 5M (Illumina Inc, San Diego, CA, USA) single nucleotide polymorphism (SNP) platform was used to genotype 175 patients with rotator cuff tear. Genotypes were used to select a set of 2595 genetically matched Caucasian controls available from the Illumina iControls database. Tests of association were performed with Genome-wide Efficient Mixed Model Association (GEMMA) software at 69 SNPs that fell within 20 kb of 6 candidate genes (DEFB1, DENND2C, ESRRB, FGF3, FGF10, and FGFR1).

RESULTS

Tests of association revealed 1 significantly associated SNP occurring in ESRRB (rs17583842; P = 4.4E-4). Another SNP within ESRRB (rs7157192) had a nominal P value of 7.8E-3. FastPHASE software estimated 2 frequent haplotypes among 54 individuals who carried both risk alleles at these 2 SNPs. The first haplotype had a frequency of 13.9% (n = 15) in risk-allele carriers and only 2.2% in controls (odds ratio, 6.9; 95% confidence interval, 3.9-2.2). The second haplotype had a frequency of 12.9% in risk-allele carriers and only 2.7% in controls (odds ratio, 5.3; 95% confidence interval, 3.0-9.5).

CONCLUSIONS

The significant association and the presence of high-risk haplotypes identified in the ESRRB gene confirm the association of variants in ESRRB and rotator cuff disease.

Incidence of familial tendon dysfunction in patients with full-thickness rotator cuff tears

Background

A familial predisposition to the development of rotator cuff tearing has been previously reported. Very little information exists on the development of global tendon dysfunction in patients with rotator cuff tears. The purpose of the current study was to determine the incidence of global tendon dysfunction as well as the need for surgery for tendon dysfunction in patients with rotator cuff tears and their family members and compare them to age-matched controls.

Methods

Ninety two patients with full-thickness rotator cuff tears and 92 age-matched controls with no history of shoulder dysfunction or surgery responded to several questions regarding tendon diseases in themselves as well as their family members. Individuals were queried regarding the presence of tendon diseases other than the rotator cuff, the need for surgery on these other tendinopathies, the presence of family members having tendinopathies including rotator cuff disease, and the need for family members to have surgery for these problems. Chi-square analysis was performed to compare the incidences between cases and controls (P<0.05 was considered significant).

Results

The average age of patients in the rotator cuff tear group and control groups were 58.24±7.4 and 58.42±8.5 years, respectively (P=0.876). Results showed 32.3% of patients in the rotator cuff tear group reported that family members had a history of rotator cuff problems or surgery compared to only 18.3% of the controls (P=0.035), and 38.7% of patients in the rotator cuff tear group reported they had a history of other tendon problems compared to only 19.3% of individuals in the control group (P=0.005).

Conclusion

Individuals with rotator cuff tears report a higher incidence of family members having rotator cuff problems or surgery as well as a higher incidence of other tendinopathies compared to controls. This data further supports a familial predilection for the development of rotator cuff tearing and generalized tendinopathies.

Evidence of genetic variations associated with rotator cuff disease

BACKGROUND

Rotator cuff disease (RCD) is a complex process influenced by a multitude of factors, and a number of gene pathways are altered in rotator cuff tears. Polymorphisms in these genes can lead to an extended tendon degeneration process, which explains why subsets of patients are more susceptible to RCD.

MATERIALS AND METHODS

Twenty-three single-nucleotide polymorphisms within 6 genes involved in repair and degenerative processes (DEFB1, DENND2C, ESRRB, FGF3, FGF10, and FGFR1) were investigated in 410 patients, 203 with a diagnosis of RCD and 207 presenting with absence of RCD. Exclusion criteria were patients older than 60 years and younger than 45 years with a history of trauma, rheumatoid arthritis, autoimmune syndrome, pregnancy, and use of corticosteroids. Genomic DNA was obtained from saliva samples. Genetic markers were genotyped with TaqMan real-time polymerase chain reaction. The χ(2) test compared genotypes and haplotype differences between groups. Multivariate logistic regression analyzed the significance of many covariates and the incidence of RCD.

RESULTS

Statistical analysis revealed female sex (P = .001; odds ratio, 2.07 [1.30-3.30]) and being white (P = .002; odds ratio, 1.88 [1.21-2.90]) to be risk factors for RCD development. A significant association of haplotypes CCTTCCAG in ESRRB (P = .05), CGACG in FGF3 (P = .01), CC in DEFB1 (P = .03), and FGFR1 rs13317 (P = .02) with RCD could be observed. Also, association between FGF10 rs11750845 (P = .03) and rs1011814 (P = .01) was observed after adjustment by ethnic group and sex.

CONCLUSIONS

Our work clearly supports the role of DEFB1, ESRRB, FGF3, FGF10, and FGFR1 genes in RCD. Identification of these variants can clarify causal pathways and provide a clue for therapeutic targets.

A history of shoulder surgery

Shoulder surgery has emerged from being a marginalised sub-speciality to being an area of much research and advancement within the last seventy years. This has been despite the complexity of the joint, and success majorly rests on parallel development of biomedical technology. This article looks at the past and present of shoulder surgery and discusses future directions in the speciality.

Arthroscopic treatment for cuff tear: strength recovery at 12 months of follow-up

The rotator cuff tear is one of the most frequent musculoskeletal disorders, but the real incidence is not clearly known because it's usually asymptomatic, even if it's more common in patients with shoulder pain (36%). The prevalence of the complete tear among general population is estimated approximately around 20.7% and it is more usual with the increasing of the age. The aim of this study is to evaluate a group of patients with any size of full-thickness cuff tear treated by arthroscopic technique, comparing the clinical and functional recovery (isokinetic, isotonic and isometric strength) with the un-operated side. Between October 2009 and June 2011, 74 patients, mean age 59 (20-72) years old, underwent arthroscopic treatment for rotator cuff tear. Forty-two patients were finally included in the study, 20 men and 22 women, mean age of 55 (20-68) years old. The mean follow-up was 12 months (6-23 months). The strength of each patient's shoulder, both operated and un-operated, was evaluated using isokinetic, isotonic and isometric tests (BIODEX Medical System). The functional outcome showed no significant differences between operated and un-operated shoulder, confirmed by Constant-Murley score and DASH score. The isokinetic, isotonic and isometric tests are valid support to clinical evaluation in order to obtain an objective data on shoulder recovery.

Elevated plasma levels of TIMP-1 in patients with rotator cuff tear

BACKGROUND AND PURPOSE

Extracellular matrix remodeling is altered in rotator cuff tears, partly due to altered expression of matrix metalloproteinases (MMPs) and their inhibitors. It is unclear whether this altered expression can be traced as changes in plasma protein levels. We measured the plasma levels of MMPs and their tissue inhibitors (TIMPs) in patients with rotator cuff tears and related changes in the pattern of MMP and TIMP levels to the extent of the rotator cuff tear.

METHODS

Blood samples were collected from 17 patients, median age 61 (39-77) years, with sonographically verified rotator cuff tears (partial- or full-thickness). These were compared with 16 age- and sex-matched control individuals with sonographically intact rotator cuffs. Plasma levels of MMPs and TIMPs were measured simultaneously using Luminex technology and ELISA.

RESULTS

The plasma levels of TIMP-1 were elevated in patients with rotator cuff tears, especially in those with full-thickness tears. The levels of TIMP-1, TIMP-3, and MMP-9 were higher in patients with full-thickness tears than in those with partial-thickness tears, but only the TIMP-1 levels were significantly different from those in the controls.

INTERPRETATION

The observed elevation of TIMP-1 in plasma might reflect local pathological processes in or around the rotator cuff, or a genetic predisposition in these patients. That the levels of TIMP-1 and of certain MMPs were found to differ significantly between partial and full-thickness tears may reflect the extent of the lesion or different etiology and pathomechanisms.

Epidemiology, natural history, and indications for treatment of rotator cuff tears

The etiology of rotator cuff disease is likely multifactorial, including age-related degeneration and microtrauma and macrotrauma. The incidence of rotator cuff tears increases with aging with more than half of individuals in their 80s having a rotator cuff tear. Smoking, hypercholesterolemia, and genetics have all been shown to influence the development of rotator cuff tearing. Substantial full-thickness rotator cuff tears, in general, progress and enlarge with time. Pain, or worsening pain, usually signals tear progression in both asymptomatic and symptomatic tears and should warrant further investigation if the tear is treated conservatively. Larger (>1-1.5 cm) symptomatic full-thickness cuff tears have a high rate of tear progression and, therefore, should be considered for earlier surgical repair in younger patients if the tear is reparable and there is limited muscle degeneration to avoid irreversible changes to the cuff, including tear enlargement and degenerative muscle changes. Smaller symptomatic full-thickness tears have been shown to have a slower rate of progression, similar to partial-thickness tears, and can be considered for initial nonoperative treatment due to the limited risk for rapid tear progression. In both small full-thickness tears and partial-thickness tears, increasing pain should alert physicians to obtain further imaging as it can signal tear progression. Natural history data, along with information on factors affecting healing after rotator cuff repair, can help guide surgeons in making appropriate decisions regarding the treatment of rotator cuff tears. The management of rotator cuff tears should be considered in the context of the risks and benefits of operative versus nonoperative treatment. Tear size and acuity, the presence of irreparable changes to the rotator cuff or glenohumeral joint, and patient age should all be considered in making this decision. Initial nonoperative care can be safely undertaken in older patients (>70 years old) with chronic tears; in patients with irreparable rotator cuff tears with irreversible changes, including significant atrophy and fatty infiltration, humeral head migration, and arthritis; in patients of any age with small (<1 cm) full-thickness tears; or in patients without a full-thickness tear. Early surgical treatment can be considered in significant (>1 cm-1.5 cm) acute tears or young patients with full-thickness tears who have a significant risk for the development of irreparable rotator cuff changes.

Lessons we can learn from gene expression patterns in rotator cuff tears and tendinopathies

Persistently high failure rates that are reported after rotator cuff repairs have encouraged greater understanding of the pathophysiology that underlies rotator cuff tears. Biologic changes that contribute to the pathogenesis of rotator cuff tears and tendinopathies, as well as adaptation after these changes, have been well described. A subset of patients with a genetic predisposition to early onset of rotator cuff tears and earlier symptom and disease progression have been identified. Many biologic changes occurring at the gene level have been identified. Pathways that are believed to contribute to rotator cuff tendinopathies include extracellular matrix remodeling, angiogenesis, changes in metabolism, apoptosis, and stress-related genes. Metaplasia of rotator cuff cells is contributed to by changes in gene expression. Modification of these gene changes may be possible through mechanical loading, drugs, or cellular manipulation. Gene changes may offer greater insight into why certain tears fail to heal and help to identify therapeutic targets.

Wound healing differences between Yorkshire and red Duroc porcine medial collateral ligaments identified by biomechanical assessment of scars

BACKGROUND

Currently, there are no large animal models to assess potential genetic contributions to ligament biomechanics during an injury repair response. Yorkshire and red Duroc pigs display phenotypically and genetically different skin wound healing responses; red Duroc skin scars were hyper-contracted and hyper-pigmented, whereas Yorkshire skin scars were not. Such findings raise the question whether connective tissues of synovial joints display a similar differential healing response in these pig breeds. This study assessed medial collateral ligament healing in Yorkshire and red Duroc pigs at the functional (biomechanical) level.

METHODS

Surgical injury was created in the right hind limb medial collateral ligament of Yorkshire and red Duroc pigs. After 10 weeks of healing, low-load (laxity and creep) and high-load (failure) mechanical properties were measured.

FINDINGS

Large, complete ligament scars formed by 10 weeks post-injury. A differential healing response was observed between the breeds, where red Duroc ligament scars had larger cross-sectional areas, exhibited greater static and total creep responses, failed at greater deformations and strains (P ≤ 0.05), and failed with strong trends for higher loads and lower moduli (P=0.06) than Yorkshire ligament scars.

INTERPRETATION

The ligament healing response of red Duroc pigs differs from Yorkshire pigs. Previously observed breed differences in dorsal skin wound healing are not restricted to skin. Such findings support a genetic basis for breed differences in response to connective tissue injury. Since this animal model is physiologically comparable to humans, these findings could provide further insight into identification of specific genetic contributions to ligament repair in human populations.

Biological factors in the pathogenesis of rotator cuff tears

Rotator cuff tears are common, and lead to shoulder pain and functional impairment. Despite their frequency and related disability, etiology and pathogenesis are still debated. Multiple factors contribute to tears of the rotator cuff. Extrinsic factors are anatomic variables, such as acromial morphologic characteristics, os acromiale, and acromial spurs that compress the rotator cuff by bony impingement or direct pressure from the surrounding soft tissue. Intrinsic factors arise from the tendon itself, because of tensile overload, aging, microvascular supply, traumatisms, or degeneration. Little information is available from a cellular and molecular point of view. We reviewed the biological factors involved in the pathogenesis of rotator cuff tears. Understanding the mechanism of rotator cuff pathology would facilitate the rationale for therapeutic interventions, by guiding the design, selection, and implementation of treatment strategies such as biologic modulation and preventive measures.

Expression of matrix metalloproteinases 1, 3, and 9 in differing extents of tendon retraction in the torn rotator cuff

PURPOSE

Differing extents of tendon retraction are found in full-thickness rotator cuff tears. The pathophysiologic context of tendon degeneration and the extent of tendon retraction are unclear. Tendon integrity depends on the extracellular matrix, which is regulated by matrix metalloproteinases (MMP). It is unknown which enzymes play a role in tendon degeneration. The hypotheses are that (1) the expression of MMPs 1, 3, and 9 is altered in the torn rotator cuff when compared with healthy tendon samples; and (2) that there is a relationship between MMP expression and the extent of tendon retraction in the torn cuff.

METHODS

Rotator cuff tendon samples of 33 patients with full-thickness rotator cuff tears (Bateman grade III) were harvested during reconstructive surgery. Samples were dehydrated and paraffin-embedded. Immunohistologic determination of MMP 1, 3, and 9 expression was performed by staining sample slices with MMP antibody. The extent of tendon retraction was determined intraoperatively according to Patte's classification and patients were assigned to 4 groups (control group, and by tendon retraction grade Patte I-III). The control group consisted of six healthy tendon samples.

RESULTS

Expression of MMPs 1 and 9 was significantly higher in torn cuff samples than in healthy tendons whereas MMP 3 expression was significantly decreased (P < 0.05). MMP 9 expression significantly increased with rising extent of tendon retraction in the torn cuff (P < 0.05). No significant association was found between expression of MMPs 1 and 3 and the rising extent of tendon retraction by Patte's classification.

CONCLUSION

Elevated expression of MMPs 1 and 9 as well as decreased MMP 3 expression can be detected in torn rotator cuff tendon tissue. There is a significant association between the extent of tendon retraction and MMP 9 expression. The results of this study give evidence that early surgical treatment of small and partial-thickness rotator cuff tears is required.