Histological and molecular analysis of the biceps tendon long head post-tenotomy

Predicting anterior cruciate ligament degeneration using magnetic resonance imaging: Insights from histological evaluation

BACKGROUND

Mucoid degeneration of the anterior cruciate ligament is a pathological condition that may impair knee mechanics and contribute to the symptomatology of osteoarthritis. This study aimed to evaluate whether preoperative magnetic resonance imaging can predict anterior cruciate ligament degeneration, specifically mucoid degeneration, and to elucidate the histopathological characteristics of mucoid degeneration in knee osteoarthritis patients.

METHODS

We evaluated a total of 95 knees of osteoarthritis patients (23 males, 72 females; mean age: 72.7 ± 7.5) scheduled for total knee arthroplasty. The relationship between preoperative magnetic resonance imaging findings and the histopathological evidence of anterior cruciate ligament mucoid degeneration was examined. Immunohistochemical analysis was employed for collagen types (COL-I, COL-II), chondrogenesis (SOX9), and vascularity (CD31).

RESULTS

High signal intensity on magnetic resonance imaging showed a positive correlation with Alcian Blue staining areas (rs = 0.59, p < 0.01) and the swelling index (rs = 0.62, p < 0.01), indicating advanced mucoid degeneration. The absence of synovial lining around the anterior cruciate ligament was associated with more severe degeneration. In the histological evaluations, advanced degeneration was characterized by an increase in chondroid metaplasia and collagen disorientation. The Alcian Blue and SOX9 correlation was positive (rs = 0.69, p < 0.01), but negative with COL-I (rs = -0.38, p = 0.03) and vascularity (CD31) (rs = -0.60, p < 0.01).

CONCLUSIONS

Preoperative magnetic resonance imaging is an effective tool in assessing the severity of anterior cruciate ligament degeneration; it influences surgical decisions. High signal intensity on magnetic resonance images denotes advanced mucoid degeneration. The absence of synovial lining around the anterior cruciate ligament is associated with more severe degeneration and may accelerate degenerative changes. Chondroid metaplasia and collagen disorientation mark advanced degeneration. Magnetic resonance imaging can be used to gauge the degree of anterior cruciate ligament degeneration in osteoarthritis.

The major pain source of rotator cuff-related shoulder pain: A narrative review on current evidence

BACKGROUND

Rotator cuff-related shoulder pain (RCRSP) was proposed to have a complex pain mechanism, but the exact aetiology is still unclear. A recent review summarised the updated research to analyse the traditional concept of shoulder impingement which may not be accurate. Current studies have demonstrated that mechanical factors including a reduction in subacromial space, scapular dyskinesia and different acromial shapes are unlikely directly contributing to RCRSP.

AIMS

Since the precise RCRSP pain mechanism remains unclear, the aim of this narrative review is to discuss possible sources of pain contributing to RCRSP according to the mechanisms-based pain classifications.

RESULTS AND DISCUSSION

Research findings on potential mechanical nociceptive factors of RCRSP are conflicting; investigations of neuropathic and central pain mechanisms of RCRSP are limited and inconclusive. Overall, available evidence has indicated moderate to strong correlations between RCRSP and chemical nociceptive sources of pain.

CONCLUSION

Results from current research may provide new directions for future studies on the aetiology of RCRSP and its clinical management towards a biochemical view instead of the traditional mechanical hypothesis.

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

BACKGROUND

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

QUESTION/PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

CLINICAL RELEVANCE

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

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.

Characterization of murine subacromial bursal-derived cells

PURPOSE/AIM

The purpose of this study is to identify a cell population within the murine subcromial bursal-derived cells with characteristics compatible to an accepted mesenchymal stem cell description given by the International Society for Cellular Therapy (ISCT).

MATERIALS AND METHODS

Murine subacromial bursa was harvested using microsurgical technique. Subacromial bursal-derived cells were classified through colony-forming units, microscopic morphology, fluorescent-activated cell sorting, and differentiation into chondrogenic, adipogenic, and osteogenic lineages.

RESULTS

Subacromial bursal samples exhibited cell growth out of the tissue for an average of 115 ± 29 colony-forming units per 1 mL of complete media. Subacromial bursal-derived cells exhibited a long, spindle-shaped, fibroblast-like morphology. Subacromial bursal-derived cells positively expressed mesenchymal stem cell markers CD73, CD90, and CD105, and negatively expressed mesenchymal stem cell markers CD31 and CD45. Subacromial bursal-derived cells, examined by Image J analysis and quantitative gene expression, were found to differentiate into chondrogenic, adipogenic, and osteogenic lineages.

CONCLUSIONS

This study demonstrated the feasibility of harvesting murine subacromial bursal tissue and identified a cell population within the subacromial bursa with characteristics compatible to an accepted mesenchymal stem cell description. The results of this study suggest that the mouse subacromial bursal-derived cell population harbors mesenchymal stem cells. Murine subacromial bursal tissue is a potential source for obtaining cells with mesenchymal stem cell characteristics for future utilization in orthopedic research to look into treatment of rotator cuff pathology.

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.

Histopathology of long head of biceps tendon removed during tenodesis demonstrates degenerative histopathology and not inflammatory changes

Background

The aim of this study is to describe and quantitatively analyze the histopathology of proximal long head biceps (LHB) tendinopathy in patients who have undergone LHB tenodesis. The hypothesis is that severe histopathologic changes of the LHB tendon (LHBT) will most likely be reflected with improved postoperative clinical outcomes.

Methods

The study included patients with isolated LHB tendinopathy or LHB tendinopathy associated with concomitant shoulder pathologies. All had failed conservative treatment (12 months) and had a positive pain response (> 50% reduction) pre-operatively after LHB tendon injection with local anesthetic. All underwent biceps tenodesis procedure between 2008 and 2014. Tendon specimens were collected and histologically analyzed with the semi-quantitative Bonar scoring system. Minimum follow-up time was 1 year. A subset of patients was retrospectively reviewed postoperatively and evaluated employing visual analogue score (VAS), short form survey (SF-12), American Shoulder and Elbow Surgeon (ASES) score, Disability of Arm, Shoulder and Hand (DASH) score, and Oxford Shoulder Score (OSS) and postoperative return to work status.

Results

Forty-five biceps tendon specimens were obtained from 44 patients (mean age 50 ± 9.6 years). Histopathological analyses demonstrated advanced degenerative changes with myxoid degeneration and marked collagen disorganization. Minimal inflammation was identified. There were no regional differences in histopathological changes. Clinical outcomes did not correlate significantly with severity of histopathologic changes.

Conclusions

This study confirms that LHBT specimens in patients undergoing tenodesis demonstrate with the use of the Bonar score histopathologic changes of chronic degeneration and not inflammation. The correct histopathologic terminology for this process is LHB tendinosis. The histopathological changes appear uniform throughout the entire length of the LHBT which may inform the nature of the procedure performed.

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

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

Análise de terminações nervosas no complexo labrum-bíceps superior usando imunohistoquímica de fluorescência e microscopia a laser confocal

Objetivos As estruturas capsulo-ligamentares do ombro funcionam como estabilizadores estáticos, juntamente com os músculos do bíceps e do manguito rotador, aumentando a superfície de contato da cavidade glenoide. Terminações nervosas livres e mecanorreceptores foram identificados no ombro; no entanto, existem alguns estudos que descrevem a presença desses nervos na inserção do bíceps. Este estudo teve como objetivo descrever a morfologia e distribuição de terminações nervosas utilizando imunofluorescência com protein gene product 9.5 (PGP 9.5) e microscopia confocal.

Métodos Foram estudados seis complexos labrum-bíceps de seis cadáveres congelados frescos. Os espécimes foram cortados coronalmente e preparados pelo método de imunofluorescência. Tanto em hematoxilina e eosina (H&E) quanto em imunofluorescência, foi descrita a organização do tecido conjuntivo com fibras paralelas de colágeno.

Resultados No estudo de H&E, foram visualizadas estruturas vasculares e algumas estruturas nervosas, que foram identificadas pela presença alongada da célula nervosa. Todas as amostras analisadas com imunofluorescência e microscopia confocal demonstraram baixa ocorrência de morfotipos de corpúsculos sensoriais e terminações nervosas livres. Identificamos terminações nervosas livres localizadas no labrum, inserção bicipital e terminações nervosas esparsas ao longo do tendão. Terminais corpusculares com aspecto fusiforme, cuneiforme e oval foram identificados no tendão.

Conclusão Esses achados corroboram a hipótese de que a geração de dor nas lesões labrais superiores de anterior a posterior (SLAP, na sigla em inglês) deriva da parte mais proximal do cabo longo do bíceps e ainda mais do labrum superior. Estudos quantitativos futuros com um número maior de espécimes podem fornecer mais informações sobre esses sistemas sensoriais.

Healing of partial tear of the supraspinatus tendon after atelocollagen injection confirmed by MRI: A case report

RATIONALE

Recently, collagen therapy has been made available for treating rotator cuff tendon injuries. However, to our knowledge, there are no clinical studies objectively investigating the effect of collagen therapy.

PATIENT CONCERNS

A 53-year-old female patient visited our pain clinic because of pain in the right shoulder. Although she had never experienced trauma and had not overused her shoulder and arm, the patient showed limited range of motion with painful arc syndrome. Moreover, the Neer test and Hawkins-Kennedy test were positive with subacromial tenderness.

DIAGNOSES

The MRI findings revealed partial tears on the articular surface of the anterior supraspinatus tendon in the rotator cuff.

INTERVENTIONS

The patient was treated with injections of exogenous collagen at the site of the partial tear under ultrasound guidance.

OUTCOMES

Follow-up MRI after injection of collagen revealed healing of the previous partial rupture of the tendon without any complications. Moreover, the patient reported reduction in pain and improvement in the movement of her shoulder during the follow-up period.

LESSONS

In this report, we demonstrate healing of a partial tear of the supraspinatus tendon in the rotator cuff after injection of exogenous collagen, as confirmed by MRI.

The inflamed biceps tendon as a pain generator in the shoulder: A histological and biomolecular analysis

INTRODUCTION

The long head of the biceps (LHB) is often resected in shoulder surgery. However, its contribution to inflammatory processes in the shoulder remains unclear. In the present study, inflamed and noninflamed human LHBs were comparatively characterized for features of inflammation.

MATERIALS AND METHODS

Twenty-two resected LHB tendons were classified into inflamed ( n = 11) and noninflamed ( n = 11) samples. For histological examination, samples were stained with hematoxylin eosin, Azan, van Gieson, and Masson Goldner trichrome. Neuronal tissue was immunohistochemically visualized. In addition, specific inflammatory marker gene expression of primary LHB-derived cell cultures were analyzed.

RESULTS

Features of tendinopathy, such as collagen disorganization, infiltration by inflammatory cells, neovascularization, and extensive neuronal innervation were found in the tendinitis group. Compared to noninflamed samples, inflamed LHBs showed a significantly increased inflammatory marker gene expression.

CONCLUSION

Structural and biomolecular differences of both groups suggest that the LHB tendon acts as an important pain generator in the shoulder joint. These findings can, on the one hand, contribute to the understanding of the biomolecular genesis of LHB tendinitis and, on the other hand, provide possibilities for new therapeutic approaches.

Molecular Pattern and Density of Axons in the Long Head of the Biceps Tendon and the Superior Labrum

The type II superior labrum anterior to posterior (SLAP) repair is a viable option in young and demanding patients, although a prolonged period of pain after surgery is described in the literature. The reason for this fact remains unknown. Thus, the purpose of this study was to investigate the molecular pattern of the biceps tendon anchor, where the sutures for repair are placed. The long head of the biceps tendon (LHBT), including the superior labrum, was dissected in the setting of reverse total shoulder arthroplasty. Immunohistochemical staining was performed using neurofilament (NF) and protein gene product (PGP) 9.5 as general markers for axons and calcitonin gene-related peptide (CGRP) and substance P for nociceptive transmission. A quantitative assessment was performed according to the two regions of interest (ROIs), i.e., the anterosuperior (ROI I) and the posterosuperior labrum (ROI II). Eleven LHBTs with a mean age of 73 years (range: 66–87 years) were harvested intraoperatively. Six LHBTs were gained in osteoarthrosis and five in fractures. We found an inhomogeneous distribution of axons in the anterosuperior and posterosuperior parts of the labrum in all the specimens irrespective of the age, gender, and baseline situation. There was a significantly higher number (p < 0.01) as well as density (p < 0.001) of NF-positive axons in ROI I compared to ROI II. Nociceptive fibers were always found along the NF-positive axons. Thus, our results indicate that the biceps tendon anchor itself is a highly innervated region comprising different nerve qualities. The anterosuperior labrum contains a higher absolute number and density of axons compared to the posterosuperior parts. Furthermore, we were able to prove the presence of nociceptive fibers in the superior labrum. The results obtained in this study could contribute to the variability of pain after SLAP repair.

Identification of Inflammatory Mediators in Tendinopathy Using a Murine Subacromial Impingement Model

Subacromial impingement is associated with a spectrum of disorders-including rotator cuff disease-but their relationship is complex. We have established a novel murine model of subacromial impingement to study supraspinatus tendinopathy. The purpose of this study was to evaluate changes in gene expression in this murine shoulder impingement model to further elucidate the mechanisms underlying the development of tendinopathy. Twenty-eight C57BL/6 mice were used in this study. All mice underwent bilateral surgery with insertion of a small metal clip in the subacromial space or a sham procedure. The supraspinatus tendons underwent histological analyses, biomechanical testing, and RNA extraction for multiplex gene expression analysis (NanoString, Seattle, WA). Histology demonstrated increased cellularity and disorganized collagen fibers of the supraspinatus tendon in the clip impingement group. Mean load to failure (5.20 vs. 1.50 N, p < 0.001) and mean stiffness (4.95 vs. 1.47 N/mm, p < 0.001) were lower in the impingement group than the sham group. NanoString analyses revealed 111 differentially expressed genes (DEGs) between the impingement and sham groups. DEGs of interest included Mmp3 (expression ratio [ER]: 2.68, p = 0.002), Tgfb1 (ER: 1.76, p = 0.01), Col3a1 (ER: 1.66, p = 0.03), and Tgfbr2 (ER: 1.53, p = 0.01). Statement of clinical significance: We identified 111 DEGs that may contribute to the development of tendinopathy in this model. Further studies of these specific genes will allow identification of their roles in the initiation and regulation of tendon damage, and their potential to serve as novel therapeutic targets in the treatment of rotator cuff disease. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2575-2582, 2019.

Clinical Outcomes After Biceps Tenodesis or Tenotomy Using Subpectoral Pain to Guide Management in Patients With Rotator Cuff Tears

PURPOSE

To assess whether preoperative subpectoral tenderness in patients with rotator cuff tears was associated with arthroscopic findings of tendinopathy of the long head of the biceps, as well as whether they had resolution of their subpectoral tenderness postoperatively after tenodesis or tenotomy.

METHODS

Patients presenting between 2011 and 2016 undergoing arthroscopic rotator cuff repair were evaluated preoperatively with the subpectoral biceps test (SBT). This test is performed with the arm adducted and internally rotated to allow palpation of the biceps as it courses under the pectoralis major tendon. Preoperative SBT findings determined operative management with either tenodesis or tenotomy during rotator cuff repair. Patients were followed up postoperatively to assess resolution of subpectoral tenderness with a repeated SBT. Preoperative and postoperative Single Assessment Numeric Evaluation (SANE), American Shoulder and Elbow Surgeons, and Constant-Murley scores were recorded in all patients.

RESULTS

A total of 128 patients were enrolled in the study, with a mean age of 58 years (range, 33-82 years). Patients with a positive preoperative SBT (n = 68) had significantly lower SANE and Constant-Murley scores preoperatively (P < .01) than patients with a negative SBT (n = 60). All patients with a positive preoperative SBT underwent either tenodesis or tenotomy, with 94% of patients (n = 64) having resolution of subpectoral pain and tenderness at final follow-up. Intraoperatively, 93% of patients with a positive SBT showed gross pathologic changes in the tendon (fraying, erythema, tears, or subluxation) compared with only 65% of patients with negative preoperative examination findings (P < .01). American Shoulder and Elbow Surgeons, Constant-Murley, and SANE scores were significantly increased postoperatively in all patients (P = .02).

CONCLUSIONS

In this group of patients with rotator cuff tears surgically treated with concomitant biceps tenodesis or tenotomy, 94% had resolution of their subpectoral tenderness. A positive SBT was associated with gross pathologic changes of the biceps in 93% of patients.

LEVEL OF EVIDENCE

Level III, prospective comparative study.

Imaging of long head biceps tendon. A multimodality pictorial essay

The aim of this is article is to provide an  imaging review of normal anatomy, most common anatomical variants and pathologies of the long head of the biceps tendon (LHB) encountered during the daily practice.

MRI, arthroscopic and histopathologic cross correlation in biceps tenodesis specimens with emphasis on the normal appearing proximal tendon

PURPOSE

To correlate the histopathologic appearances of resected long head of the biceps tendon (LHBT) specimens following biceps tenodesis, with pre-operative MRI and arthroscopic findings, with attention to the radiologically normal biceps.

MATERIAL AND METHODS

Retrospective analysis of patients who had undergone preoperative MRI, subsequent arthroscopic subpectoral tenodesis for SLAP tears and histopathologic inspection of the excised sample between 2013 and 16. Those with a normal MRI appearance or mildly increased intrasubstance signal were independently analyzed by 2 blinded radiologists. A blinded orthopedic surgeon and pathologist reviewed all operative imaging and pathologic slides, respectively.

RESULTS

Twenty-three LHBT resected samples were identified on MRI as either normal (Reader 1 n = 15; Reader 2 n = 14) or demonstrating low-grade increased signal (Reader 1 n = 8; Reader 2 n = 9). Of these, 86.9% demonstrated a histopathological abnormality. 50% of samples with histopathological abnormality demonstrated normal appearance on MRI. The most common reported histopathology finding was myxoid degeneration (73.9%) and fibrosis (52.2%). The most common arthroscopic abnormality was fraying (18.2%) and erythema (13.6%). Utilizing histopathology as the gold standard, the two radiologists demonstrated a sensitivity of 35.0% v 42.9%, specificity of 66.7% v 100%, PPV of 87.5% v 100%, and NPV of 13.3% v 14.3%. Corresponding arthroscopic inspection demonstrated a sensitivity of 31.6%, specificity of 66.6%, PPV 85.7% and NPV of 13.3%. There was moderate agreement between the two radiologists, κ = 0.534 (95% CI, 0.177 to 0.891), p = 0.01.

CONCLUSION

Histopathological features of low grade tendinosis including mainly myxoid degeneration and fibrosis are frequently occult on MR imaging.

Biceps tenodesis versus biceps tenotomy for biceps tendinitis without rotator cuff tears

Disorders of the long head of the biceps tendon (LHB) are a well-recognised cause of shoulder pain despite the function of the long head of the biceps remaining poorly understood. There has been a dramatic rise in the number of biceps tenodesis procedures being performed in the last decade. This may partly be attributed to concerns regarding residual cosmetic deformity and pain after biceps tenotomy though there is little evidence to suggest that functional outcomes of tenodesis are superior to biceps tenotomy. Current literature focuses on LHB disorders with concomitant rotator cuff tears. The aim of this review is to discuss the anatomy of the LHB, the pathogenesis of tendinopathy of the LHB, indications of biceps tenodesis and tenotomy and compare the current literature on the functional outcomes of these procedures for LHB disorders in the absence of rotator cuff tears.

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

BACKGROUND

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

PURPOSE

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

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

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

RESULTS

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

CONCLUSION

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

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.

Fibrocartilaginous metaplasia identified in the long head of the biceps brachii

BACKGROUND

In the glenohumeral joint, the long head of biceps brachii (LHBB) is exposed to tension and compression loading. The short head of biceps brachii (SHBB) works only in tension. It is known that tendon under compression might develop fibrocartilaginous metaplasia that improves the resistance to compression but reduces the resistance to tension. This study evaluated the presence of cartilage in LHBB and SHBB samples, supporting its possible role in tendon tear.

METHODS

Between 2014 and 2016, 13 samples of LHBB and SHBB were collected during surgery for shoulder instability, glenohumeral arthritis, and massive rotator cuff tears. The samples were stained with hematoxylin and eosin, safranin-O, and Alcian blue (pH 1.0) for light microscopy. Immunohistochemistry was performed using anti-S100, anti-collagen I and II, and anti-tenascin-C antibodies.

RESULTS

Histochemistry: LHBB samples showed matrix disorganization, with clusters of chondrocyte surrounded by collagen fibers and glycosaminoglycans. Safranin-O showed evident metachromasia. SHBB samples did not show any matrix disorganization or cartilaginous metaplasia. Immunohistochemistry: In all LHBB samples, anti-S100 and anti-collagen II showed cartilage in proximity of the tendon tear. Tenascin C immunostained closely to the disorganized matrix areas. SHBB, however, showed no positive areas for S-100, anti-collagen II, or tenascin C.

CONCLUSIONS

According to our results, we hypothesize that the repeated stimulation in compression may induce the formation of fibrous cartilage. However, to date its role in tendon pathology remains to be clearly defined.

Neurofilament distribution in the superior labrum and the long head of the biceps tendon

BACKGROUND

The postoperative course after arthroscopic superior labrum anterior to posterior (SLAP) repair using suture anchors is accompanied by a prolonged period of pain, which might be caused by constriction of nerve fibres. The purpose was to histologically investigate the distribution of neurofilament in the superior labrum and the long head of the biceps tendon (LHBT), i.e. the location of type II SLAP lesions.

METHODS

Ten LHBTs including the superior labrum were dissected from fresh human specimen and immunohistochemically stained against neurofilament (NF). All slides were scanned at high resolution and converted into tagged image file format, and regions of interest (ROIs) were defined as follows: ROI I-superior labrum anterior to the LHBT origin, ROI II-mid-portion of the superior labrum at the origin of the LHBT, ROI III-superior labrum posterior to the LHBT origin and ROI IV-the most proximal part of the LHBT before its attachment to the superior labrum. The entire images were automatically segmented according to the defined ROIs and measured using a programmed algorithm specifically created for this purpose. The NF-positive cells were counted, and their total size and the area of other tissue were measured separately for the different ROIs.

RESULTS

Distribution of NF-positive cells in absolute numbers revealed a clear but insignificantly higher amount in favour of ROI I, representing the superior labrum anterior to the LHBT origin. Setting ROI I at 100%, a significant difference could be seen compared to ROI III, representing the superior labrum posterior to the LHBT origin (ROI I vs. ROI III with a p value < 0.05).

CONCLUSIONS

Summarizing, the density of neurofilament is inhomogeneously distributed throughout the superior labrum with the highest number of neurofilament in the anterior superior labrum. Thus, suture placement in type II SLAP repair could play an important role for the postoperative pain-related outcome.

Influence of repetitive mechanical loading on MMP2 activity in tendon fibroblasts

Matrix metalloproteinase2 has been implicated in tendon pathology caused by repetitive movements. However, its activity in the early stages of the tendon's response to overuse, and its presence in the circulation as a possible indicator of tendon degradation, remain unknown. Human tendon cells were repetitively stretched for 5 days, and the rabbit Achilles tendon complex underwent repetitive motion 3× per week for 2 weeks. Quantitative polymer chain reaction analysis was performed to detect matrix metalloproteinase2/14 and tissue inhibitor of matrix metalloproteinase2 messenger ribonucleic acid of cells and rabbit tissue, and matrix metalloproteinase2 protein levels were determined with an enzyme linked immunoassay. Matrix metalloproteinase2 activity was examined using zymography of the conditioned media, tendon and serum. Immunohistochemistry was used to localize matrix metalloproteinase2 in tendon tissue, and the density of fibrillar collagen in tendons was examined using second harmonic generation microscopy. Tendon cells stretched with high strain or high frequency demonstrated increased matrix metalloproteinase2 messenger ribonucleic acid and protein levels. Matrix metalloproteinase2 activity was increased in the rabbit Achilles tendon tissue at weeks 1 and 2; however, serum activity was only increased at week 1. After 2 weeks of exercise, the collagen density was lower in specific regions of the exercised rabbit Achilles tendon complex. Matrix metalloproteinase2 expression in exercised rabbit Achilles tendons was detected surrounding tendon fibroblasts. Repetitive mechanical stimulation of tendon cells results in a small increase in matrix metalloproteinase2 levels, but it appears unlikely that serum matrix metalloproteinase2 will be a useful indicator of tendon overuse injury. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1991-2000, 2016.

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

The long head of the biceps tendon (LHBT) occupies a unique proximal intra-articular and distal extra-articular position within the human shoulder. In the presence of a rotator cuff (RC) tear, the LHBT is recruited into an accelerated role undergoing potential mechanical and biochemical degeneration. Intra-articular sections of the LHBT were harvested during primary shoulder arthroplasty from patients with an intact or deficient RC. LHBTs were stained (H&E, Alcian Blue) and subjected to histologic analysis using the semiquantitative Bonar scale and measurement of collagen orientation. LHBTs (n = 12 per group) were also subjected to gene-expression analyses via an RT(2) -PCR Profiler Array quantifying 84 genes associated with cell-cell and cell-matrix interactions. LHBTs (n = 18 per group) were biomechanically tested with both stress-relaxation and load-to-failure protocols and subsequently modeled with the Quasilinear Viscoelastic (QLV) and Structural-Based Elastic (SBE) models. While no histologic differences were observed, significant differences in mechanical testing, and viscoelastic modeling parameters were found. PCR arrays identified five genes that were differentially expressed between RC-intact and RC-deficient LHBT groups. LHBTs display signs of pathology regardless of RC status in the arthroplasty population, which may be secondary to both glenohumeral joint arthritis and the additional mechanical role of the LHBT in this population.

Proteomics perspectives in rotator cuff research: a systematic review of gene expression and protein composition in human tendinopathy

BACKGROUND

Rotator cuff tendinopathy including tears is a cause of significant morbidity. The molecular pathogenesis of the disorder is largely unknown. This review aimed to present an overview of the literature on gene expression and protein composition in human rotator cuff tendinopathy and other tendinopathies, and to evaluate perspectives of proteomics--the comprehensive study of protein composition--in tendon research.

MATERIALS AND METHODS

We conducted a systematic search of the literature published between 1 January 1990 and 18 December 2012 in PubMed, Embase, and Web of Science. We included studies on objectively quantified differential gene expression and/or protein composition in human rotator cuff tendinopathy and other tendinopathies as compared to control tissue.

RESULTS

We identified 2199 studies, of which 54 were included; 25 studies focussed on rotator cuff or biceps tendinopathy. Most of the included studies quantified prespecified mRNA molecules and proteins using polymerase chain reactions and immunoassays, respectively. There was a tendency towards an increase of collagen I (11 of 15 studies) and III (13 of 14), metalloproteinase (MMP)-1 (6 of 12), -9 (7 of 7), -13 (4 of 7), tissue inhibitor of metalloproteinase (TIMP)-1 (4 of 7), and vascular endothelial growth factor (4 of 7), and a decrease in MMP-3 (10 of 12). Fourteen proteomics studies of tendon tissues/cells failed inclusion, mostly because they were conducted in animals or in vitro.

CONCLUSIONS

Based on methods, which only allowed simultaneous quantification of a limited number of prespecified mRNA molecules or proteins, several proteins appeared to be differentially expressed/represented in rotator cuff tendinopathy and other tendinopathies. No proteomics studies fulfilled our inclusion criteria, although proteomics technologies may be a way to identify protein profiles (including non-prespecified proteins) that characterise specific tendon disorders or stages of tendinopathy. Thus, our results suggested an untapped potential for proteomics in tendon research.

The anatomy and histology of the bicipital tunnel of the shoulder

BACKGROUND

The bicipital tunnel is the extra-articular, fibro-osseous structure that encloses the long head of the biceps tendon.

METHODS

Twelve cadaveric shoulder specimens underwent in situ casting of the bicipital tunnel with methyl methacrylate cement to demonstrate structural competence (n = 6) and en bloc harvest with gross and histologic evaluation (n = 6). The percentage of empty tunnel was calculated histologically by subtracting the proportion of cross-sectional area of the long head of the biceps tendon from that of the bicipital tunnel for each zone.

RESULTS

Cement casting demonstrated that the bicipital tunnel was a closed space. Zone 1 extended from the articular margin to the distal margin of the subscapularis tendon. Zone 2 extended from the distal margin of the subscapularis tendon to the proximal margin of the pectoralis major tendon. Zone 3 was the subpectoral region. Zones 1 and 2 were both enclosed by a dense connective tissue sheath and demonstrated the presence of synovium. Zone 3 had significantly greater percentage of empty tunnel than zones 1 and 2 did (P < .01).

CONCLUSION

The bicipital tunnel is a closed space with 3 distinct zones. Zones 1 and 2 have similar features, including the presence of synovium, but differ from zone 3. A significant bottleneck occurs between zone 2 and zone 3, most likely at the proximal margin of the pectoralis major tendon. The bicipital tunnel is a closed space where space-occupying lesions may produce a bicipital tunnel syndrome. Careful consideration should be given to surgical techniques that decompress both zones 1 and 2 of the bicipital tunnel.

Tendinopathy of the long head of the biceps tendon: histopathologic analysis of the extra-articular biceps tendon and tenosynovium

BACKGROUND

Bicipital tendinitis is a common cause of anterior shoulder pain, but there is no evidence that acute inflammation of the extra-articular long head of the biceps (LHB) tendon is the root cause of this condition. We evaluated the histologic findings of the extra-articular portion of the LHB tendon and synovial sheath in order to compare those findings to known histologic changes seen in other tendinopathies.

METHODS

Twenty-six consecutive patients (mean age 45.4±13.7 years) underwent an open subpectoral biceps tenodesis for anterior shoulder pain localized to the bicipital groove. Excised tendons were sent for histologic analysis. Specimens were graded using a semiquantitative scoring system to evaluate tenocyte morphology, the presence of ground substance, collagen bundle characteristics, and vascular changes.

RESULTS

Chronic inflammation was noted in only two of 26 specimens, and no specimen demonstrated acute inflammation. Tenocyte enlargement and proliferation, characterized by increased roundness and size of the cell and nucleus with proteoglycan matrix expansion and myxoid degenerative changes, was found in all 26 specimens. Abundant ground substance, collagen bundle changes, and increased vascularization were visualized in all samples.

CONCLUSION

Anterior shoulder pain attributed to the biceps tendon does not appear to be due to an inflammatory process in most cases. The histologic findings of the extra-articular portion of the LHB tendon and synovial sheath are similar to the pathologic findings in de Quervain tenosynovitis at the wrist, and may be due to a chronic degenerative process similar to this and other tendinopathies of the body.

Effects of repetitive platelet-rich plasma application on human tenocyte proliferation

Current clinical application of platelet-rich plasma is showing a trend toward multiple treatments. The goal of this study was to show the benefit of interval platelet-rich plasma application in the healing and recovery of human tenocytes using an in vitro cell model. Eight volunteers (6 men and 2 women) were included in this study (mean±SD age, 31.6±10.9 years). Venous blood was collected from new blood draws at 3 different times. Two blood products were prepared on each day of treatment: platelet-rich plasma derived from a single-spin process (PRPSS) and platelet-rich plasma derived from a double-spin process (PRPDS). The study had 2 limbs: 2-day and 4-day intervals. Cell proliferation, measured as disintegrations per minute, was then examined via a radioactive thymidine assay. In the 2-day-interval group, the difference in disintegrations per minute between days 0 and 2 in the PRPSS group reached statistical significance (P =.006). In the PRPDS group, statistical difference was seen between days 0 and 4 (P=.001) and between days 2 and 4 (P=.030). In the 4-day-interval group, the difference in disintegrations per minute between days 4 and 8 in the PRPSS group reached statistical significance, showing a decrease in cell proliferation (P =.013). In the PRPDS group, a statistical difference was seen between days 0 and 8 (P=.021), also showing a decrease in cell proliferation. The greatest effect of platelet-rich plasma, which has a positive effect on tenocyte proliferation and recovery, is seen on initial application. Its effect is diminished with repetitive application, and this finding leads to questioning of the efficacy of interval platelet-rich plasma dosing.

Identification of differentially expressed genes and small molecule drugs for the treatment of tendinopathy using microarray analysis

Tendinopathy is a critical clinical problem as it is often asymptomatic at onset and during development, and is only recognized upon rupture of the tendon. It is common among recreational and competitive athletes. The present study sought to examine the molecular mechanism of the progression of tendinopathy by screening out differentially expressed genes (DEGs) and investigating their functions. In addition, the present study aimed to identify the small molecules, which exhibit potential effects, which could be utilized for the treatment of tendinopathy. The gene expression profile of tendinopathy, GSE26051 was downloaded from the Gene Expression Omnibus database, which included 23 control samples and 18 samples of tendinopathy. The DEGs were identified using the Limma package in the R programming language, and gene ontology and pathway enrichment analysis were performed. In addition, the potential regulatory microRNAs and the target sites of the transcription factors were screened out based on the molecular signature database. In addition, the DEGs were mapped to the connectivity map database to identify the potential small molecule drugs. A total of 318 genes were filtered as DEGs between diseased samples and normal control tendons. Additionally, genes, including laminin, α4, platelet‑derived growth factor α, laminin γ1 and Src homology 2 transforming protein 1 may induce tendinopathy through the focal adhesion pathway. Furthermore, the transcription factor, lymphoid enhancer‑binding factor 1 and its target genes, pantothenate kinase 2 and G protein‑coupled receptor kinase 5 were identified. The most significant microRNA, miR‑499, was screened and was found to regulate specific genes, including CUGBP2 and MYB. Additionally, the small molecules, Prestwick‑1082 and viomycin were identified to have the potential to repair disordered metabolic pathways and furthermore to remedy tendinopathy. The results of the present study assessed the mechanism of tendinopathy and screened small molecule drugs as potential treatments for this condition. In addition, the present findings have the potential for use in a clinical setting for the treatment of tendinopathy in the future.

Quantitative ultrasound facilitates the exploration of morphological association of the long head biceps tendon with supraspinatus tendon full thickness tear

Backgrounds

Pathology of the long head biceps tendon (LHBT) is associated with rotator cuff tears but whether the LHBT texture changes following supraspinatus tendon full thickness tear (SSFT) can be detected at the extra-articular segment remains unknown. This cross-sectional study aimed to explore the morphological differences of the LHBT in shoulders with and without deficient rotator cuffs by using quantitative ultrasound.

Materials and Methods

We selected 145 cases with SSFT and 145 age-and- gender-matched controls. The width, thickness, flattening ratio, cross-sectional area, and echogenicity ratio of the LHBT were measured and a general linear model was used to clarify the relationship between rotator cuff pathology and LHBT morphology. The receiver operating characteristic curves of each parameter were constructed for SSFT discrimination and the maximal Youden indexes were used to define the best cut-off points.

Results

We found increased thickness and cross-sectional area but decreased flattening ratio in shoulders with SSFT, and no between-group differences in the width and echogenicity ratio. The LHBT appearance was modified by biceps peritendinous effusion and medial subluxation, but not by the size of SSFT. The flattening ratio was the best discriminator for SSFT with an area under curve of 0.81 (95% confidence interval, 0.76–0.86). The cut-off values to differentiate between the non-tear and tear groups were 2.00 mm of the thickness, 1.73 of the flattening ratio and 10.53 mm² of the cross-sectional area.

Conclusion

Quantitative ultrasound facilitated the detection of the LHBT morphological changes following SSFT and demonstrated its potential utility in discriminating rotator cuff deficiency.

Scapular dyskinesis is detrimental to shoulder tendon properties and joint mechanics in a rat model

Shoulder tendon injuries are frequently seen in the presence of abnormal scapular motion, termed scapular dyskinesis. The cause and effect relationship between scapular dyskinesis and shoulder injury has not been directly defined. We developed and used an animal model to examine the initiation and progression of pathological changes in the rotator cuff and biceps tendon. Sixty male Sprague-Dawley rats were randomized into two groups: nerve transection (to induce scapular dyskinesis, SD) or sham nerve transection (control). The animals were euthanized 4 and 8 weeks after surgery. Shoulder function and passive joint mechanics were evaluated over time. Tendon mechanical, histological, organizational, and compositional properties were evaluated at both time points. Gross observation demonstrated alterations in scapular motion, consistent with scapular "winging." Shoulder function, passive internal range of motion, and tendon mechanical properties were significantly altered. Histology results, consistent with tendon pathology (rounded cell shape and increased cell density), were observed, and protein expression of collagen III and decorin was altered. This study presents a new model of scapular dyskinesis that can rigorously evaluate cause and effect relationships in a controlled manner. Our results identify scapular dyskinesis as a causative mechanical mechanism for shoulder tendon pathology.

Overuse activity in the presence of scapular dyskinesis leads to shoulder tendon damage in a rat model

Shoulder tendon injuries are common clinical conditions and are a significant source of pain and dysfunction. These conditions are more common in individuals who perform repetitive overhead activities and in individuals who have abnormal scapular kinematics, termed scapular dyskinesis (SD). However, the long term consequences associated with overuse activity in the presence of SD are unknown. Therefore, the objective of this study was to determine the effect of overuse in combination with SD on joint mechanics and properties of the rotator cuff and biceps tendons. A rat model of scapular dyskinesis was used. Ninety adult male Sprague-Dawley rats (400-450 g) were randomized into three groups: nerve transection (SD), sham nerve transection + overuse (OV), or nerve transection + overuse (SD + OV). Rats were sacrificed at 2, 4, and 8 weeks after surgery. Shoulder function and passive joint mechanics were evaluated over time and tendon properties (mechanical, histological, organizational, and compositional) were measured. Results demonstrated that overuse activity and SD are each independently detrimental to tendon properties (e.g., diminished mechanical properties, disorganized collagen). However, tendon damage caused by the addition of overuse may be worse, with more parameters altered, than damage caused by the addition of SD. This study helps define the mechanical mechanisms leading to tendon damage and provides a framework for distinguishing treatment strategies for active patients and those with abnormal scapular mechanics.

Biomechanical and biochemical protective effect of low-level laser therapy for Achilles tendinitis

For three decades, low level laser therapy (LLLT) has been used for treatment of tendinitis as well as other musculoskeletal diseases. Nevertheless, the biological mechanisms involved remain not completely understood. In this work, the effects of LLLT and of the widely used nonsteroidal anti-inflammatory drug, diclofenac, have been compared in the case of collagenase-induced Achilles tendinitis. Wistar rats were treated with diclofenac or laser therapy. The tensile behavior of tendons was characterized through successive loading-unloading sequences. The method considered 11 characteristic parameters to describe the mechanical behavior. It was shown that during the acute inflammatory process of the tendon, the mechanical properties were significantly correlated to the high levels of MMP-3, MMP-9 and MMP-13 expression presented in a previous paper (Marcos, R.L., et al., 2012). The treatment by non-steroidal anti-inflammatory drugs such as diclofenac sodium produces a low protective effect and can affect the short-term biochemical and biomechanical properties. On the contrary, it is shown that LLLT exhibits the best results in terms of MMPs reduction and mechanical properties recovery. Thus, LLLT looks to be a promising and consistent treatment for tendinopathies.

Histomorphologic changes of the long head of the biceps tendon in common shoulder pathologies

PURPOSE

To assess molecular and histologic differences between the proximal (intra-articular) and distal (extra-articular) portions of the long head of the biceps (LHB) tendon in 3 different disease states (biceps instability, tendinosis, and degenerative joint disease [DJD]) compared with a healthy tendon (fresh frozen).

METHODS

We used 32 LHB tendons of patients undergoing tenodesis (mean age, 54.7 ± 10.1 years) and 9 harvested tissue donors. Tendons were divided according to 4 diagnostic groups: (1) biceps instability, (2) tendinosis, (3) DJD, and (4) normal control. After sectioning, tendons were fixed in formalin and stained with H&E and alcian blue for histologic analysis. Measurements of collagen organization by use of polarized light microscopy was then performed, and protein expression for type I and type III collagen, tenascin C, and decorin was determined.

RESULTS

There were no statistical differences found for protein expression of type I or type III collagen, tenascin C, or decorin. The proximal and distal regions of the tendons had statistically significant differences in alcian blue staining, with the proximal portion containing a higher amount of proteoglycan (instability, P = .001; tendinosis, P = .005; DJD, P = .008; control, P = .011). When compared with the nonpathologic control tendons, a significant increase in alcian blue staining for the proximal region was seen in all 3 groups. Total polarized light analysis showed that the distal tendon had a significantly higher intensity (organization) compared with the proximal tendon (P < .001); this was also seen in all of the diagnostic groups (instability, P = .010; tendinosis, P = .013; DJD, P = .07; control, P = .028).

CONCLUSIONS

This study showed a greater degree of degeneration of the proximal (intra-articular) regions of the LHB tendon when compared with the distal regions in all pathologic groups. However, no major differences at the cellular level were found among groups.

CLINICAL RELEVANCE

The pathomechanisms of the various forms of known LHB diagnoses are not yet fully understood and basic science studies may help in understanding their etiology and therefore optimizing treatment options.

Metalloproteases and their inhibitors are altered in both torn and intact rotator cuff tendons

BACKGROUND

We evaluated the role of matrix metalloproteases (MMPs) and their inhibitors which are involved in extracellular matrix remodeling and degradation, in the pathogenesis of chronic rotator cuff tears.

MATERIALS AND METHODS

Tendon samples were harvested from 13 patients who underwent arthroscopic repair of a rotator cuff tear. Supraspinatus biopsy specimens were harvested en bloc from the arthroscopically intact middle portion of the tendon more than 1 cm from the torn edge, from the lateral edge of the tear, and from the superior one third of the macroscopically intact subscapularis tendon used as control. Histological analysis and an evaluation of the activity of specific metalloproteases and the tissue inhibitors of metalloprotease (TIMP-1, TIMP-2) was done blindly by multiplex sandwich ELISA (Search-Light technology) in each specimen

RESULTS

Histological evidence of tendinopathy was present in all patients with a tear of the rotator cuff, and not in the macroscopically intact subscapularis tendon. There was a significant increase in MMP 1, MMP 2, MMP 3 and in TIMP-1, TIMP-2 levels in all specimens examined, including the macroscopically intact portion of the supraspinatus tendon and in the control specimens

CONCLUSIONS

The tissue in the ruptured area of the supraspinatus tendon undergoes marked rearrangement at molecular levels. This involves the activity of MMP 1, 2 and 3, and supports the critical role of MMPs in the tendon physiology. Seemingly intact parts of the injured supraspinatus tendon can present tendinopathic features, with altered cellular metabolism.

Evidence of sympathetic innervation and α1-adrenergic receptors of the long head of the biceps brachii tendon

BACKGROUND

The primary purpose of this study was to investigate the sympathetic innervation of the long head of the biceps brachii tendon LHB via immunohistochemical staining for protein S-100 and neuropeptide Y (NPY) in patients with complex proximal humerus fractures, in individuals with chronic biceps tendinosis in the setting of large rotator cuff tears (RC), and in cadaveric samples with no previously reported shoulder pathology.

METHODS

We investigated the presence of sympathetic innervation and α1-adrenergic receptors of the long head of the biceps brachii tendon (LHB) in patients with complex proximal humerus fractures and individuals with chronic biceps tendinosis in the setting of large rotator cuff tears (RC). The correlation of morphological features with immunohistochemical evidence of neural element presence was also investigated. Forty-one LHB tendon specimens were examined. Seventeen were harvested from patients who underwent hemiarthroplasty for proximal humerus fractures, 14 were from individuals with biceps tendinosis in the context of a large RC tear, and ten were from cadaveric controls with no previous shoulder pathology. Histologic examination was performed using hematoxylin and eosin. Immunohistochemistry was used to detect the expression of the protein S-100, neuropeptide Y, and α1-adrenergic receptors, as well as to characterize the potential neural differentiation of tendon cells.

RESULTS

A strong correlation between the expression of NPY/S-100, α1-adrenergic/S-100, and α1-adrenergic/NPY was found. The LHB tendon has sympathetic innervation and α1-adrenergic receptors in acute and chronic pathological conditions.

CONCLUSION

Our results provide useful guidance on the management of tendinosis and the handling of the LHB in hemiarthroplasties for fractures.

In vitro changes in human tenocyte cultures obtained from proximal biceps tendon: multiple passages result in changes in routine cell markers

PURPOSE

Results of in vitro cell models are commonly used to promote new therapies (e.g., platelet-rich plasma), and clinicians have to be aware of the specific limitations of such models. To gain a sufficient and effective cell load, many current in vitro models use cells multiplied through various passages. This is especially important in tendon-like cell (TLC) models, since native tendon tissue is not available unlimited and contains limited amount of tenocytes. The purpose was to determine the occurrence of phenotypic changes following extended monolayer culture of TLCs, according to cell-passage number.

METHODS

Tendon samples were obtained from 15 healthy patients undergoing biceps tenodesis. Tendons were digested and cultured (monolayer) for six passages. Tendon-specific markers (collagens I and III, decorin, tenascin-C, and tenomodulin) and their histology were analyzed using gene expression and protein content assays. Native cells, the cells cultured and cells passaged one to six times were analyzed at each passage.

RESULTS

Gene expression of types I and III collagen of cultured TLCs significantly decreased after two passages. Gene expression of decorin, tenascin-C, and tenomodulin exhibited a trend of decreased gene expression with increased passage. Protein levels of types I and III collagen and decorin decreased after four passages.

CONCLUSIONS

The significant findings let conclude that tenocyte-like cells obtained from human LHB can be maintained in monolayer culture at low passages, before the signs of phenotypic drift are present. But researchers must be aware of rapid phenotypic drift at higher passage numbers. Therefore, only cells within the first 3 passages should be used as a precaution for in vitro monolayer cell models, and one has to be aware of the phenotypic changes if TLCs passaged multiple times are used. The clinical relevance of this data is that understanding of in vitro TLC models, and their limitations may finally help the clinician to judge the potential of experimental data of new biologic treatment options.

The aging athlete: part 2, "boomeritis" of the upper extremity

OBJECTIVE

The purpose of this review is to describe the upper extremity injuries that frequently accompany aging, the typical clinical presentations, and the differential diagnoses with an emphasis on the injury most likely encountered with each presentation.

CONCLUSION

Expectation of continued participation in exercise and sports activities by the baby boomer population has presented new challenges to the medical field. The concepts behind factors that predispose older athletes to certain pathologic conditions that affect the muscles, tendons, and bones of the upper extremity must be understood.

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

INTRODUCTION

The pathogenesis of rotator cuff disease (RCD) is complex and not fully understood. This systematic review set out to summarise the histological and molecular changes that occur throughout the spectrum of RCD.

METHODS

We conducted a systematic review of the scientific literature with specific inclusion and exclusion criteria.

RESULTS

A total of 101 studies met the inclusion criteria: 92 studies used human subjects exclusively, seven used animal overuse models, and the remaining two studies involved both humans and an animal overuse model. A total of 58 studies analysed supraspinatus tendon exclusively, 16 analysed subacromial bursal tissue exclusively, while the other studies analysed other tissue or varying combinations of tissue types including joint fluid and muscle. The molecular biomarkers that were altered in RCD included matrix substances, growth factors, enzymes and other proteins including certain neuropeptides.

CONCLUSIONS

The pathogenesis of RCD is being slowly unravelled as a result of the significant recent advances in molecular medicine. Future research aimed at further unlocking these key molecular processes will be pivotal in developing new surgical interventions both in terms of the diagnosis and treatment of RCD.

Intra-articular changes precede extra-articular changes in the biceps tendon after rotator cuff tears in a rat model

HYPOTHESIS

Biceps tendon pathology is common with rotator cuff tears. The mechanisms for biceps changes, and therefore its optimal treatment, are unknown. Our objective was to determine the effect of rotator cuff tears on regional biceps tendon pathology. We hypothesized that histologic and compositional changes would appear before organizational changes, both would appear before mechanical changes, and changes would begin at the tendon's insertion site.

MATERIALS AND METHODS

Detachment of supraspinatus and infraspinatus tendons or sham surgery was done in 65 Sprague-Dawley rats. Rats were euthanized at 1, 4, or 8 weeks for regional measurements of histologic, compositional, organizational (1, 4 and 8 weeks), or mechanical properties (4 and 8 weeks only).

RESULTS

One week after tendon detachments, decreased organization and more rounded cell shape were found in the intra-articular space of the biceps tendon. Aggrecan expression was increased along the entire length of the tendon, whereas all other compositional changes were only at the tendon's proximal insertion into bone. With time, this disorganization and more rounded cell shape extended the length of the tendon. Organizational and cell shape changes also preceded detrimental mechanical changes: decreased modulus in the intra-articular space was found after 8 weeks.

CONCLUSIONS

Results support a degenerative component to pathology in the biceps tendon. In addition, changes resembling a tendon exposed to compressive loading occurring first in the intra-articular space indicate that the biceps tendon plays an increased role as a load-bearing structure against the humeral head in the presence of rotator cuff tears.

The rotator interval and long head biceps tendon: anatomy, function, pathology, and magnetic resonance imaging

The rotator interval is an anatomically defined triangular area located between the coracoid process, the superior aspect of the subscapularis, and the anterior aspect of the supraspinatus. It is widely accepted that the rotator interval structures fulfill a role in biomechanics and pathology of the glenohumeral joint and long head biceps tendon. However, there is ongoing debate regarding the biomechanical details and the indications for treatment. A better understanding of rotator interval anatomy and function will lead to improved treatment of rotator interval abnormalities, and guide the indications for imaging and surgical intervention.

Role of metalloproteinases in rotator cuff tear

The role of matrix metalloproteinases (MMPs) and their inhibitors (TIMPS) in the pathophysiology of rotator cuff tears has not been established yet. Recent advances empathize about the role of MMPs and TIMPS in extracellular matrix (ECM) remodeling and degradation in rotator cuff tears pathogenesis and healing after surgical repair. An increase in MMPs synthesis and the resulting MMPs mediated alterations in the ECM of tendons have been implicated in the etiopathogenesis of tendinopathy, and there is an increase in the expression of MMPs and a decrease in TIMP messenger ribonucleic acid expression in tenocytes from degenerative or ruptured tendons. Importantly, MMPs are amenable to inhibition by cheap, safe, and widely available drugs such as the tetracycline antibiotics and bisphosphonates. A better understanding of relationship and activity of these molecules could provide better strategies to optimize outcomes of rotator cuff therapy.

Bone marrow-derived mesenchymal stem cells obtained during arthroscopic rotator cuff repair surgery show potential for tendon cell differentiation after treatment with insulin

PURPOSE

The purpose of this study was to determine whether a one-time physiologic dose of insulin when compared with the growth factors insulin-like growth factor 1, β-fibroblastic growth factor, and growth differentiation factor 5 is capable of differentiating bone marrow-derived mesenchymal stem cells (MSCs) into tendon.

METHODS

Eleven patients undergoing arthroscopic rotator cuff repair consented to undergo aspiration of bone marrow. A dose-response curve was calculated to determine the optimal dose of insulin needed to differentiate MSCs into tendon. After purification of bone marrow in the operating room, MSCs were exposed to either insulin or tendon-inducing growth factors or were left untreated to serve as a control. The potential for MSCs in each of these groups to differentiate into tendon was evaluated with a multistep process that included determination of the genetic upregulation for tendon-specific proteins, confirmation that the levels of these proteins were actually increased, staining of the MSCs with antibodies for these proteins to ensure that they were expressed on the cell surface, and finally, evaluation of cell morphology to verify the MSCs' tendon-like appearance.

RESULTS

MSCs treated with insulin showed increased gene expression of tendon-specific markers (P < .05), increased content of tendon-specific proteins (P < .05), and increased receptors on the cell surface (P < .05) compared with control cells. Histologic analysis showed a tendon-like appearance compared with the control cells.

CONCLUSIONS

Bone marrow-derived MSCs treated with a single physiologic dose of insulin differentiated into cells with characteristics consistent with tendon.

CLINICAL RELEVANCE

The potential for MSCs to differentiate into tendon after a 1-time dose of insulin may assist in developing practical biologic options for augmentation of rotator cuff repairs.

Biceps tendon properties worsen initially but improve over time following rotator cuff tears in a rat model

Damage to the biceps tendon is often seen in conjunction with rotator cuff tears. However, controversy exists regarding its role in the shoulder and its optimal treatment. A previous study determined that biceps tendons were detrimentally affected in the presence of rotator cuff tears in the rat model and this damage worsened over time. However, whether this damage progresses at later time points to provide a chronic model is unknown. The objective of this study was to determine the changes in the biceps tendon in the presence of a cuff tear over time. Our hypothesis was that histological, compositional, organizational, and mechanical properties would worsen with time. We detached the supraspinatus and infraspinatus tendons of 48 rats and evaluated these properties at 1, 4, 8, and 16 weeks postdetachment. Properties worsened through 8 weeks, but improved between 8 and 16 weeks. We therefore conclude that biceps tendon changes in this model are not truly chronic. Additionally, it has been shown that infraspinatus properties in this model return to normal by 16 weeks, when biceps properties improve, indicating that earlier repair of one or more of the rotator cuff tendons may lead to resolved pathology of the long head of the biceps tendon.

Expression of matrix metalloproteinases 1, 3, and 9 in degenerated long head biceps tendon in the presence of rotator cuff tears: an immunohistological study

Background

Long head biceps (LHB) degeneration, in combination with rotator cuff tears, can be a source of chronic shoulder pain. LHB tenotomy reduces pain and improves joint function although the pathophysiological context is not well understood. Tendon integrity depends on the extracellular matrix (ECM), which is regulated by matrix metalloproteinases (MMP). It is unclear which of these enzymes contribute to LHB but we chose to study MMP 1, 3, and 9 and hypothesized that one or more of them may be altered in LHB, whether diagnosed preoperatively or intraoperatively. We compared expression of these MMPs in both LHB and healthy tendon samples.

Methods

LHB samples of 116 patients with degenerative rotator cuff tears were harvested during arthroscopic tenotomy. Patients were assigned to 4 groups (partial thickness tear, full thickness tear, cuff arthropathy, or control) based upon intraoperative findings. Partial and full thickness tears were graded according to Ellman and Bateman's classifications, respectively. MMP expression was determined by immunohistochemistry.

Results

MMP 1 and 9 expression was significantly higher in the presence of rotator cuff tears than in controls whereas MMP 3 expression was significantly decreased. MMP 1 and 9 expression was significantly higher in articular-sided than bursal-sided partial thickness tears. No significant association was found between MMP 1 and 9 expression and full thickness tears, and the extent of the cuff tear by Bateman's classification.

Conclusion

Increased MMP 1 and 9 expression, and decreased MMP 3 expression are found in LHB degeneration. There is a significant association between the size and location of a rotator cuff tear and MMP expression.

The relevance of long head biceps degeneration in the presence of rotator cuff tears

BACKGROUND

Long head biceps (LHB) degeneration in combination with rotator cuff tears can be a source of chronic shoulder pain. LHB tenotomy is an approved surgical procedure for pain reduction and improvement of joint function, however, the pathophysiology of LHB degeneration is not fully understood. In the literature, neoangiogenesis in tendon tissue has previously been shown to be associated with tendon degeneration. Vascular Endothelial Growth Factor (VEGF) is an important inducer of neoangiogenesis. The hypotheses are first that an elevated VEGF expression and vessel density can be found in degenerated LHB tissue and second that there is a relation between VEGF expression, vessel density and the different types of rotator cuff tears.

METHODS

LHB samples of 116 patients with degenerative rotator cuff tears were harvested during arthroscopic tenotomy. The samples were dehydrated and paraffin embedded. VEGF expression was determined using immunohistochemistry. Vessel density and vessel size were determined on Masson-Goldner stained tissue sections. On the basis of intraoperative findings, patients were assigned to 4 different groups (control group, partial thickness rotator cuff tear, full thickness rotator cuff tear and cuff arthropathy). Partial thickness rotator cuff tears were classified according to Ellman grade I-III, full thickness rotator cuff tears according to Bateman's classification (grade I-IV). The control group consisted of eight healthy tendon samples.

RESULTS

VEGF expression in the LHB was significantly higher in the presence of rotator cuff tears than in healthy tendons (p < 0.05) whereas vessel density and vessel size were significantly higher in the LHB of patients with cuff arthropathy (p < 0.05). Furthermore, there was significantly higher VEGF expression in LHB samples from patients with articular-sided compared to bursal-sided partial thickness rotator cuff tears (p < 0.05). No significant dependence was found between VEGF expression, vessel size and vessel density in LHB of patients with full thickness rotator cuff tears and the extent of the cuff tear following Bateman's classification.

CONCLUSION

Elevated VEGF expression can be detected in degenerated LHB tissue. The quantity of VEGF expression and vessels are related to the extent of LHB degeneration.