The impact of rotator cuff deficiency on structure, mechanical properties, and gene expression profiles of the long head of the biceps tendon (LHBT): Implications for management of the LHBT during primary shoulder arthroplasty

Imaging and histological evaluation of the long head of the biceps tendon in the presence of different types of rotator cuff tears

BACKGROUND

A comparison of changes in the long head of the biceps tendon for different types of rotator cuff tears has not been previously performed. Furthermore, the correlation between the thickening and degeneration of the long head of the biceps tendon and the cause of these changes have not been fully clarified. We evaluated the relationship between degenerative changes in the long head of the biceps tendon and rotator cuff tears in a rat model using imaging and histology.

METHODS

Ninety-six 12-week-old Sprague-Dawley rats were divided into anterior (subscapularis tear), anterosuperior (subscapularis, supraspinatus, and infraspinatus tears), superior (supraspinatus and infraspinatus tears), and control groups. The long head of the biceps tendon was harvested at 4 or 12 weeks postoperatively. The cross-sectional areas of the intra- and extra-capsular components of the tendon were measured using micro-computed tomography, and the affected/normal ratio of the cross-sectional area was calculated. Masson's trichrome staining and Alcian blue staining were performed for histologic analysis, with degenerative changes described using the modified Bonar scale. The correlation between the affected/normal ratio and Bonar scores was evaluated.

RESULTS

The affected/normal ratio was higher for the anterior and anterosuperior groups than for the control group at 4 and 12 weeks. The ratio increased for the intra-articular portion in the superior group and for both the intra- and extra-articular portions in the anterior and anterosuperior groups. Degeneration considerably progressed in the anterior and anterosuperior groups compared with the control group from weeks 4 to 12 and was greater in the intra- than in the extra-articular portion. The ratio correlated with extracellular matrix score.

CONCLUSIONS

Subscapularis tears were associated with progressive thickening and degeneration of the long head of the biceps tendon at 4 and 12 weeks postoperatively, which was more significant in the intra- than in the extra-articular portion. Histologic evaluation indicated that the extracellular matrix likely caused these degenerative changes.

mRNA and long non-coding RNA expression profiles of rotator cuff tear patients reveal inflammatory features in long head of biceps tendon

Background

This study aimed to identify the differentially expressed mRNAs and lncRNAs in inflammatory long head of biceps tendon (LHBT) of rotator cuff tear (RCT) patients and further explore the function and potential targets of differentially expressed lncRNAs in biceps tendon pathology.

Methods

Human gene expression microarray was made between 3 inflammatory LHBT samples and 3 normal LHBT samples from RCT patients. GO analysis and KEGG pathway analysis were performed to annotate the function of differentially expressed mRNAs. The real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was admitted to verify their expression. LncRNA-mRNA co-expression network, cis-acting element, trans-acting element and transcription factor (TF) regulation analysis were constructed to predict the potential molecular regulatory mechanisms and targets for LHB tendinitis.

Results

103 differentially expressed lncRNAs and mRNAs, of which 75 were up-regulated and 28 were down-regulated, were detected to be differentially expressed in LHBT. The expressions of 4 most differentially expressed lncRNAs (A2MP1, LOC100996671, COL6A4P, lnc-LRCH1-5) were confirmed by qRT-PCR. GO functional analysis indicated that related lncRNAs and mRNAs were involved in the biological processes of regulation of innate immune response, neutrophil chemotaxis, interleukin-1 cell response and others. KEGG pathway analysis indicated that related lncRNAs and mRNAs were involved in MAPK signaling pathway, NF-kappa B signaling pathway, cAMP signaling pathway and others. TF regulation analysis revealed that COL6A4P2, A2MP1 and LOC100996671 target NFKB2.

Conclusions

LlncRNA-COL6A4P2, A2MP1 and LOC100996671 may regulate the inflammation of LHBT in RCT patients through NFKB2/NF-kappa B signaling pathway, and preliminarily revealed the pathological molecular mechanism of tendinitis of LHBT.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01292-y.

Research perspectives-Pipelines to human tendon transcriptomics

Tendon transcriptomics is a rapidly growing field in musculoskeletal biology. The ultimate aim of many current tendon transcriptomic studies is characterization of in vitro, ex vivo, or in vivo, healthy, and diseased tendon microenvironments to identify the underlying pathways driving human tendon pathology. The transcriptome interfaces between genomic, proteomic, and metabolomic signatures of the tendon cellular niche and the response of this niche to stimuli. Some of the greatest bottlenecks in tendon transcriptomics relate to the availability and quality of human tendon tissue, hence animal tissues are frequently used even though human tissue is most translationally relevant. Here, we review the variability associated with human donor and procurement factors, such as whether the tendon is cadaveric or a clinical remnant, and how these variables affect the quality and relevance of the transcriptomes obtained. Moreover, age, sex, and health demographic variables impact the human tendon transcriptome. Tendons present tissue-specific challenges for cell, nuclei, and RNA extraction that include a dense extracellular matrix, low cellularity, and therefore low RNA yield of variable quality. Consideration of these factors is particularly important for single-cell and single-nuclei resolution transcriptomics due to the necessity for unbiased and representative cell or nuclei populations. Different cell, nuclei, and RNA extraction methods, library preparation, and quality control methods are used by the tendon research community and attention should be paid to these when designing and reporting studies. We discuss the different components and challenges of human tendon transcriptomics, and propose pipelines, quality control, and reporting guidelines for future work in the field.

Advances in Microscopic Studies of Tendinopathy: Literature Review and Current Trends, with Special Reference to Neovascularization Process

Tendinopathy is a process of chaotic extracellular matrix remodeling followed by increased secretion of enzymes and mediators of inflammation. The histopathological assessment of tendinous tissue is crucial to formulate the diagnosis and establish the severity of tendon degeneration. Nevertheless, the microscopic analysis of tendinous tissue features is often challenging. In this review, we aimed to compare the most popular scales used in tendon pathology assessment and reevaluate the role of the neovascularization process. The following scores were evaluated: the Bonar score, the Movin score, the Astrom and Rausing Score, and the Soslowsky score. Moreover, the role of neovascularization in tendon degeneration was reassessed. The Bonar system is the most commonly used in tendon pathology. According to the literature, hematoxylin and eosin with additional Alcian Blue staining seems to provide satisfactory results. Furthermore, two observers experienced in musculoskeletal pathology are sufficient for tendinopathy microscopic evaluation. The control, due to similar and typical alterations in tendinous tissue, is not necessary. Neovascularization plays an ambiguous role in tendon disorders. The neovascularization process is crucial in the tendon healing process. On the other hand, it is also an important component of the degeneration of tendinous tissue when the regeneration is incomplete and insufficient. The microscopic analysis of tendinous tissue features is often challenging. The assessment of tendinous tissue using the Bonar system is the most universal. The neovascularization variable in tendinopathy scoring systems should be reconsidered due to discrepancies in studies.

The Bonar Score in the Histopathological Assessment of Tendinopathy and Its Clinical Relevance-A Systematic Review

This study aimed to perform a comprehensive systematic review, which reports the role of the Bonar score in the histopathological assessment of tendinopathy and its clinical relevance. To identify all of the studies that reported relevant information on the Bonar scoring system and tendinopathy, an extensive search of the major and the most significant electronic databases (PubMed, Cochrane Central, ScienceDirect, SciELO, Web of Science) was performed. A systematic review of the literature was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The extracted data included—year of study, geographical location, type of the study, radiological modifications, gender, number of patients, region of tendinopathy, mean age, control group, characteristics of the Bonar score and alterations in the scale, mean Bonar score, number of investigators, area of tendon investigation, clinical and radiological implications. An extensive search of the databases and other sources yielded a total of 807 articles. Eighteen papers were finally included in this systematic review, and of these, 13 original papers included the clinical and radiological implications of tendinopathy. Radiological evaluation was present in eight studies (both magnetic resonance imaging (MRI) and ultrasound (US)). The clinical implications were more frequent and present in 10 studies. Using the Bonar score, it is easy to quantify the pathological changes in tendinous tissue. However, its connection with clinical and radiological evaluation is much more complicated. Based on the current state of knowledge, we concluded that the neovascularization variable in the Bonar system should be reconsidered. Ideally, the microscopic assessment score should follow the established classification scale with the radiological and clinical agreement and should have a prognostic value.

Polymorphisms and alterations in gene expression associated with rotator cuff tear and healing following surgical repair: a systematic review

BACKGROUND

Rotator cuff tears (RCTs) are a common cause of shoulder disability, yet both conservative and surgical treatment strategies can lead to poor results in some patient populations. Enhanced understanding of the genetic processes associated with RCTs can assist in the development of more effective management options and help predict individual responses to surgical treatment. This systematic review analyzes the current literature on the genetic footprint associated with RCTs and interprets these findings to enhance the current understanding of RCT pathogenesis, potential treatment regimens, and prognostic biomarkers of outcomes after surgical repair.

METHODS

A systematic search of the Embase, PubMed, and Web of Science electronic databases was performed. Medical Subject Headings (MeSH) and Emtree index terms were formulated from the concept terms "rotator cuff tear," "genetics," and "human," and synonyms of these concepts were applied to the Web of Science search. Articles were screened against predefined inclusion and exclusion criteria. Eligible studies compared gene expression patterns and genetic polymorphisms between cases (with RCTs) and controls (without RCTs). Quality assessment was performed with studies being rated as high, moderate, or poor quality. A modified best-evidence synthesis was applied, and studies were determined to be of strong, moderate, or limited evidence.

RESULTS

The search identified 259 articles. Of these studies, 26 were eligible for review. Two studies were considered poor quality; 15 studies, moderate quality; and 9 studies, high quality. Analysis of these articles found that RCTs were associated with alterations in genes that code for the extracellular matrix, cell apoptosis, immune and inflammatory responses, and growth factor pathways. In particular, there was strong evidence of a significant association between RCTs and the genes MMP3, TNC, and ESRRB. Strong evidence of an association between BMP5 upregulation and successful healing after surgical repair was also found.

CONCLUSION

This review provides strong evidence of an genetic association with RCTs. The genotype and gene expression patterns detailed within this review can assist in deciphering the biological mechanisms resulting in RCTs, as well as predicting an individual's response to surgical repair. Future research could investigate whether manipulating these genes-or their associated signaling pathways-could assist in RCT healing and whether genetic biomarkers could be used clinically to predict patient outcomes after surgical repair of RCTs.

Regional histologic differences in the long head of the biceps tendon following subpectoral biceps tenodesis in patients with rotator cuff tears and SLAP lesions

PURPOSE

The purpose of this study was to quantify the regional histology of the long head of the biceps tendon (LHBT) and compare the histopathology present to clinical findings in patients with rotator cuff tears and SLAP lesions.

METHODS

Prospectively enrolled patients undergoing an open subpectoral LHBT tenodesis in the setting of a rotator cuff (RTC) tear or SLAP lesion. Perioperative data were collected and the excised LHBT was analyzed by a fellowship trained pathologist. Tendons were sectioned into proximal (biceps anchor), middle (bicipital groove), and distal (myotendinous junction) portions. Sections were stained with Movat's pentachrome stain and digitized for analysis. Comparisons were made between the histologic findings present in the setting of a rotator cuff tear with those seen in the setting of a SLAP tear.

RESULTS

39 tendons were analyzed: 20 from patients with SLAP lesions (mean age of 44.7 years, range 23-60 years) and 19 from patients with rotator cuff tears (mean age of 58.7 years, range 43-71). Patients with the most pathologic tendons in the bicipital groove were significantly older (59.4 vs. 50.4 years; p < 0.05), reported higher pre-operative VAS scores (6.6 vs. 5.0; p < 0.02), and demonstrated lower pre-operative ASES scores (41.6 vs. 50.7; p < 0.05). The RTC group showed significantly more mucinous degeneration at both the proximal (p < 0.03) and the middle (p < 0.01) tendon portions compared to the SLAP group. In both groups, the portions of proximal tendon showed significantly (p < 0.05) more mucinous degeneration than distal portions.

CONCLUSION

Regional histologic differences exist in the LHBT. Rotator cuff patients showed the most degenerated tendon in the bicipital groove and these patients tended to be older and have higher VAS and lower ASES scores. Surgeons should consider performing a subpectoral biceps tenodesis as the bicipital groove portion of the tendon may be very degenerated, especially in patients with rotator cuff disease. Additional research is warranted to distinguish whether treating the biceps differently in distinct geographic regions affects patient outcomes.

LEVEL OF EVIDENCE

II.

The effect of Medicaid payer status on patient outcomes following repair of massive rotator cuff tears

BACKGROUND

The influence of socioeconomic status and insurance type has not been studied extensively for RCR, particularly not in the high risk massive RCT population. The purpose of this study is to identify relationships between Medicaid payer status and patient outcomes following massive RCR.

METHODS

A retrospective review of shoulder surgery database identified 29 patients undergoing massive rotator cuff repair. Patients were stratified based on insurance type into two cohorts, Medicaid (14 patients) and non-Medicaid (15 patients). Missed routine follow-up appointments and comorbidities were recorded and compared between groups. Group comparisons were made for pre- and postoperative patient-reported and functional outcomes. Outcome scores included American Shoulder and Elbow Shoulder Score (ASES), the Penn Shoulder Score, and the Subjective Shoulder Value (SSV). A p value of < 0.05 was considered significant for all statistical analyses.

RESULTS

Medicaid patients were on average 7.1 years younger than non-Medicaid patients (49.8 vs. 56.9 years, respectively), and remaining demographics were comparable between groups. Preoperative patient-reported outcomes were only significantly different for ASES and ASES pain (p = 0.010, 0.037). There was excellent average improvement for Medicaid patients but no significant differences compared to non-Medicaid patients for ASES (p = 0.630), PENN scores (p = 0.395), and SSV (p = 0.198). Medicaid patients also had a higher number of missed and canceled appointments (28%) compared to non-Medicaid patients (18%).

CONCLUSION

Medicaid coverage will expand to millions of uninsured Americans under current healthcare reform. Medicaid patients with massive RCT appear to significantly improve with surgical treatment.

Autologous tendon-derived cell-seeded nanofibrous scaffolds improve rotator cuff repair in an age-dependent fashion

Rotator cuff tendon tears are one of the most common shoulder pathologies, especially in the aging population. Due to a poor healing response and degenerative changes associated with aging, rotator cuff repair failure remains common. Although cell-based therapies to augment rotator cuff repair appear promising, it is unknown whether the success of such a therapy is age-dependent. We hypothesized that autologous cell therapy would improve tendon-to-bone healing across age groups, with autologous juvenile cells realizing the greatest benefit. In this study, juvenile, adult, and aged rats underwent bilateral supraspinatus tendon repair with augmentation of one shoulder with autologous tendon-derived cell-seeded polycaprolactone scaffolds. At 8 weeks, shoulders treated with cells in both juvenile and aged animals exhibited increased cellularity, increased collagen organization, and improved mechanical properties. No changes between treated and control limbs were seen in adult rats. These findings suggest that cell delivery during supraspinatus repair initiates earlier matrix remodeling in juvenile and aged animals. This may be due to the relative "equilibrium" of adult tendon tissue with regards to catabolic and anabolic processes, contrasted with actively growing juvenile tendons and degenerative aged tendons. This study demonstrates the potential for autologous cell-seeded scaffolds to improve repairs in both the juvenile and aged population. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1250-1257, 2017.

Qualitative Assessment and Quantitative Analysis of the Long Head of the Biceps Tendon in Relation to the Pectoralis Major Tendon Humeral Insertion: An Anatomic Study

PURPOSE

To qualitatively assess and to quantitatively analyze the long head of the biceps tendon (LHBT) in the region of the pectoralis major (PM).

METHODS

From 11 fresh cadaveric donors, 20 cadaveric shoulders without operative scars were dissected-mean age, 76.9 years (range, 61 to 93 years); male, 75%; left-sided, 55%; mean height, 67.8 inches (range, 61 to 71 inches); mean weight, 148.1 pounds (range, 106 to 176 pounds). Two specimens with discovered ruptures were excluded. The LHBT circumference was measured at the anterior edge of supraspinatus, suprapectorally, midpectorally, and subpectorally. The muscle was then removed from the LHBT and the circumference was again measured at the supra-, mid-, and subpectoral levels. These data were used to calculate the area of the tendon. All measurements were performed by 2 independent observers. Statistical analysis was performed to assess reliability of data and the difference between serial measurements.

RESULTS

The mean calculated percentage tendon decreased from 86.7% at the superior edge of the PM to 49.8% at the midpoint of the PM and to 17.5% at the inferior edge of the PM.

CONCLUSIONS

Distal to the PM, the LHBT was composed of a small percentage of tendon to muscle, which may have implications for the mechanical strength of fixation of tenodesis. The anatomic location of the musculotendinous junction of the LHBT began proximal to the superior edge of the PM tendon, which implies that restoration of anatomic tensioning may require a more proximal docking site than previously described. Tenodesis performed between the midpoint of the PM insertion and more distal points involves a significant portion of muscle, which may not be optimal.

CLINICAL RELEVANCE

Tenodesis performed between the midpoint of the PM insertion and more distal points involves a significant portion of muscle, which may affect the mechanical strength or optimal choice of fixation location.