Etiologic and pathogenetic factors for rotator cuff tendinopathy

Partial-thickness rotator cuff tears: a review of current literature on evaluation and management

Rotator cuff disease is a common cause of shoulder pain for which partial-thickness rotator cuff tears occupy a significant proportion. Such tears are often difficult to diagnose and manage in the general clinic setting. A review of the available literature from well-known databases was performed in this study to provide a concise overview of partial-thickness rotator cuff tears to aid physicians in their understanding and management.

Immediate effects of myofascial release to the pectoral fascia on posture, range of motion, and muscle excitation: a crossover randomized clinical trial

CONTEXT

Forward shoulder posture (FSP) is a risk factor for shoulder pathology. Manual therapists often use myofascial release (MFR) to elongate restricted pectoral fascia to reduce FSP and improve shoulder function; however, the effects of this treatment approach remain anecdotal.

OBJECTIVE

Determine the acute effects of 4-min of MFR, compared to a soft-touch control (CON), to the pectoral fascia on: 1) FSP, 2) shoulder horizontal abduction ROM (HA-ROM), and 3) muscle excitation of the trapezius (upper, middle, lower [UT, MT, LT]) and pectoralis major (PEC).

METHODS

Fifty-nine right-handed participants (27 ± 9 years, 30 female) with FSP, but otherwise asymptomatic shoulders participated in a randomized crossover clinical trial by attending two experimental sessions: one MFR and one CON treatment, each administered by a Registered Massage Therapist. FSP, HA-ROM, and muscle excitation during a reaching task, were measured before and after each treatment.

RESULTS

There was a significant interaction between treatment and time for FSP (p = .018, ηp = .093) with FSP decreasing from PRE MFR (128 ± 19 mm) to POST MFR (123 ± 19 mm; p < .001, ηp = .420) and PRE CON (126 ± 19 mm) to POST CON (124 ± 18 mm; p < .001, ηp = .191) interventions. There were no significant differences in HA-ROM or muscle excitation.

CONCLUSION

Four minutes of MFR or CON to the pectoral fascia acutely reduces FSP.

Supraspinatus extraction from MRI based on attention-dense spatial pyramid UNet network

BACKGROUND

With potential of deep learning in musculoskeletal image interpretation being explored, this paper focuses on the common site of rotator cuff tears, the supraspinatus. It aims to propose and validate a deep learning model to automatically extract the supraspinatus, verifying its superiority through comparison with several classical image segmentation models.

METHOD

Imaging data were retrospectively collected from 60 patients who underwent inpatient treatment for rotator cuff tears at a hospital between March 2021 and May 2023. A dataset of the supraspinatus from MRI was constructed after collecting, filtering, and manually annotating at the pixel level. This paper proposes a novel A-DAsppUnet network that can automatically extract the supraspinatus after training and optimization. The analysis of model performance is based on three evaluation metrics: precision, intersection over union, and Dice coefficient.

RESULTS

The experimental results demonstrate that the precision, intersection over union, and Dice coefficients of the proposed model are 99.20%, 83.38%, and 90.94%, respectively. Furthermore, the proposed model exhibited significant advantages over the compared models.

CONCLUSION

The designed model in this paper accurately extracts the supraspinatus from MRI, and the extraction results are complete and continuous with clear boundaries. The feasibility of using deep learning methods for musculoskeletal extraction and assisting in clinical decision-making was verified. This research holds practical significance and application value in the field of utilizing artificial intelligence for assisting medical decision-making.

Compensation strategy of shoulder synergist muscles is not stereotypical in patients with rotator cuff repair

Rotator cuff tear is a common shoulder injury that causes shoulder dysfunction and pain. Although surgical repair is the primary treatment for rotator cuff tear, it is well recognized that impaired force exertion of muscles connecting to the involved tendon and subsequent complemental change in the force exertion of synergist muscles persist even after repair. This study aimed to identify the compensation strategy of shoulder abductors by examining how synergist muscles respond to supraspinatus (SSP) muscle force deficit in patients with rotator cuff repair. Muscle shear modulus, an index of muscle force, was assessed for SSP, infraspinatus, upper trapezius, and middle deltoid muscles in repaired and contralateral control shoulders of 15 patients with unilateral tendon repair of the SSP muscle using ultrasound shear wave elastography while the patients passively or actively held their arm in shoulder abduction. In the repaired shoulder, the shear modulus of the SSP muscle declined, whereas that of other synergist muscles did not differ relative to that of the control. To find the association between the affected SSP and each of the synergist muscles, a regression analysis was used to assess the shear moduli at the population level. However, no association was observed between them. At the individual level, there was a tendency of variation among patients with regard to a specific muscle whose shear modulus complementarily increased. These results suggest that the compensation strategy for SSP muscle force deficit varies among individuals, being nonstereotypical in patients with rotator cuff injury.

Mechanical characteristic of supraspinatus muscle changes independent of its size and intramuscular fat in patient with rotator cuff repair

PURPOSE

This study aimed i) to investigate the mechanical, morphological, and compositional characteristics of the supraspinatus muscle after rotator cuff repair by using ultrasound shear wave elastography (SWE) and B-mode imaging, and ii) to determine whether the morphological or compositional characteristics are associated with the mechanical characteristic of the supraspinatus during contraction.

METHODS

Using SWE and B-mode imaging, active and passive shear moduli, muscle thickness, and echo intensity of the supraspinatus were measured from the repaired and contralateral control shoulders of 22 patients with rotator cuff repair. The shear modulus, muscle thickness, and echo intensity were compared between the repaired and control shoulders. The association between the active shear modulus and the other variables was determined.

RESULTS

While the active and passive shear moduli were lower in the repaired shoulder compared to the control, the muscle thickness and echo intensity did not vary between them. Interestingly, the passive shear modulus was positively correlated with the active shear modulus only in the control shoulder.

CONCLUSION

The mechanical characteristic of supraspinatus remains impaired, even without degenerative changes in the morphological and compositional characteristics after rotator cuff repair. Furthermore, the association between contractile and elastic characteristics in the supraspinatus was deteriorated in control shoulder.

Anatomic characteristics of shoulder based on MRI accurately predict incomplete rotator cuff injuries in patients: relevance for predictive, preventive, and personalized healthcare strategies

Background and PPPM-related working hypothesis

In the diagnosis of incomplete rotator cuff injuries (IRCI), magnetic resonance imaging (MRI) and ultrasound examination often have false-positive and false-negative results, while arthroscopy is expensive, invasive, and complex. From the strategy of predictive, preventive, and personalized medicine (PPPM), shoulder anatomical characteristics based on MRI have been demonstrated to accurately predict IRCI and their clinical applicability for personalized prediction of IRCI.

Aims

This study aimed to develop and validate a nomogram based on anatomical features of the shoulder on MRI to identify IRCI for PPPM healthcare strategies.

Methods

The medical information of 257 patients undergoing preoperative MRI examination was retrospectively reviewed and served as the primary cohort. Partial-thickness rotator cuff tears (RCTs) and tendinopathy observed under arthroscopy were considered IRCI. Using logistic regression analyses and least absolute shrinkage and selection operator (LASSO), IRCI was identified among various preoperative factors containing shoulder MRI and clinical features. A nomogram was constructed and subjected to internal and external validations (80 patients).

Results

The following eight independent risk factors for IRCI were identified:AgeThe left injured sidesThe Goutallier classification of supraspinatus in oblique coronal positionThe Goutallier classification of supraspinatus in the axial positionAcromial thicknessAcromiohumeral distanceCoracohumeral distanceAbnormal acromioclavicular joint signalsThe nomogram accurately predicted IRCI in the development (C-index, 0.932 (95% CI, 0.891, 0.973)) and validation (C-index, 0.955 (95% CI, 0.918, 0.992)) cohorts. The calibration curve was consistent between the predicted IRCI probability and the actual IRCI ratio of the nomogram. The decision curve analysis and clinical impact curves demonstrated that the model had high clinical applicability.

Conclusions

Eight independent factors that accurately predicted IRCI were determined using MRI anatomical findings. These personalized factors can prevent unnecessary diagnostic interventions (e.g., arthroscopy) and can assist surgeons in implementing individualized clinical decisions in medical practice, thus addressing the goals of PPPM.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-023-00333-5.

Advances in the Treatment of Rotator Cuff Tears: Management of Rotator Cuff Tears in the Athlete

Unique biomechanical factors in the overhead and throwing athlete lead to a spectrum of rotator cuff pathology, usually with progressive lateralization of the supraspinatus footprint. Initial comprehensive nonoperative management is indicated for all athletes. Progression to arthroscopic debridement, repair of concomitant injuries, and possible rotator cuff repair with a transosseous equivalent technique are the current management strategies for athletes when nonoperative management fails.

Platelet lysate and tendon healing: comparative analysis of autologous frozen-thawed PRP and ketorolac tromethamine in the treatment of patients with rotator cuff tendinopathy

Platelet-rich blood derivatives are being nowadays increasingly used in the treatment of tendon-related pathologies as a rich source of growth factors. We sought to ascertain if local application of platelet lysate (PL) to augment rotator cuff repair ameliorates patient outcomes compared to ketorolac tromethamine treated group. A total of forty patients, with clinical diagnosis of Rotator Cuff Tendinopathy were randomized to receive sub acromial injections of PL every week for a total of 3 injections and two injection of ketorolac tromethamine once every two weeks. Subjective assessments included VAS, SPADI and shoulder range of motion were assessed at baseline and at 1 and 6 months after injection. Taking both control and PL groups, it was vividly seen that the outcomes were identical at the initial state, as well as the short-term one; whereas, when considering the 6-month period, there is a seemingly remarkable superiority in PL group in all parameters.

The Relationship of Aging and Smoking With Rotator Cuff Disease: A Systematic Review and Meta-analysis

OBJECTIVE

Despite rotator cuff disease being one of the most common causes of shoulder pain, its pathogenesis and biology are poorly understood. In this study, we synthesized evidence from studies reporting associations for aging and smoking status in relation to rotator cuff disease.

DESIGN

A systematic review was performed using multiple databases (PubMed, Embase, Cochrane, CINAHL, and Science Direct). Articles that met our eligibility criteria and presented data on the association between aging and/or smoking status and rotator cuff disease were included. We performed meta-analyses and reported cumulative effects using odds ratios and corresponding 95% confidence intervals.

RESULTS

Of the 212 articles eligible for full-text review, seven studies reported on the relationship between aging and rotator cuff disease, and 10 studies reported on the relationship between smoking and rotator cuff disease. Aging was consistently associated with increased odds of having rotator cuff disease when assessed continuously (per 10-yr increase: odds ratio = 1.20, 95% confidence interval = 1.18-1.21) or categorically (ages <40 yrs vs: [a] 40-44 yrs [odds ratio = 2.71, 95% confidence interval = 1.78-4.13], [b] 45-49 yrs [odds ratio = 4.33, 95% confidence interval = 2.88-6.55], and [c] ≥50 yrs [odds ratio = 6.97, 95% confidence interval = 4.85-10.01]). Assessing studies that reported smoking status as current smokers versus nonsmokers, current smokers were more likely to have rotator cuff disease (odds ratio = 1.94, 95% confidence interval = 1.52-2.48). However, a statistically significant association was not found when never smokers were compared with former smokers (odds ratio = 1.08, 95% confidence interval = 0.97-1.20) and to current smokers (odds ratio = 0.97, 95% confidence interval = 0.87-1.07).

CONCLUSIONS

In this systematic review and meta-analysis, increasing age was a strong risk factor for rotator cuff disease. The finding that current smokers are more likely to have rotator cuff disease as compared with nonsmokers implies that cessation of smoking can potentially lead to mitigation of this risk factor.

Factors Associated With Symptomatic Rotator Cuff Tears: The Rotator Cuff Outcomes Workgroup Cohort Study

OBJECTIVE

Although rotator cuff tear is one of the most common musculoskeletal disorders, its etiology is poorly understood. We assessed factors associated with the presence of rotator cuff tears in a cohort of patients with shoulder pain.

DESIGN

From February 2011 to July 2016, a longitudinal cohort of patients with shoulder pain was recruited. Patients completed a detailed questionnaire in addition to a magnetic resonance imaging scan and a clinical shoulder evaluation. The association of multiple factors associated with rotator cuff tears was assessed using multivariate logistic regression.

RESULTS

In our cohort of 266 patients, 61.3% of patients had a rotator cuff tear. Older age (per 1 yr: odds ratio = 1.03, 95% confidence interval = 1.02-1.07), involvement of the dominant shoulder (odds ratio = 2.02, 95% confidence interval = 1.16-3.52), and a higher body mass index (per 1 kg/m2: odds ratio = 1.06, 95% confidence interval = 1.03-1.12) were independently associated with rotator cuff tears. Sex, depression, smoking status, shoulder use at work, hypertension, and diabetes were not significantly associated with rotator cuff tear.

CONCLUSIONS

In a cohort of patients with shoulder pain, we identified older age, involvement of the dominant shoulder, and a higher body mass index to be independently associated with rotator cuff tear. The mechanism of how these factors possibly lead to rotator cuff tears needs further research.

TO CLAIM CME CREDITS

Complete the self-assessment activity and evaluation online at http://www.physiatry.org/JournalCME.

CME OBJECTIVES

Upon completion of this article, the reader should be able to: (1) Identify factors associated with an increased risk of developing rotator cuff tears in adults; (2) Describe the current epidemiological trends of rotator cuff tears in the United States; and (3) Discuss the pathophysiological role of aging in the development of nontraumatic rotator cuff tears.

LEVEL

Advanced.

ACCREDITATION

The Association of Academic Physiatrists is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.The Association of Academic Physiatrists designates this Journal-based CME activity for a maximum of 1.0 AMA PRA Category 1 Credit(s)™. Physicians should only claim credit commensurate with the extent of their participation in the activity.

Editorial Commentary: Biologically-Enhanced Patch Augmentation: The Perfect Marriage of Mechanical Stability and Biology for Rotator Cuff Healing? Unfortunately, Not Yet

Recurrent rotator cuff tears are a frequent cause of shoulder disability. To repair a rotator cuff, the surgeon faces both mechanical and biological challenges. Patch use as a scaffold for rotator cuff repair is well-described, as is biological augmentation, with clinical indications and efficacy being the subjects of ongoing study. However, a clinical report of dermal allograft patch augmentation combined with attempts at supercharging the biology is novel. This technique would benefit from controlled, prospective studies, with tight inclusion criteria.

Acromioplasty in the surgical operations of partial-thickness rotator cuff tears: A comprehensive review

The partial-thickness rotator cuff tears (PTRCTs) are known as a prevalent pathology, which cause inability mostly in athletes. So far, a number of treatments have been suggested depending on patient characteristics and size and location of the tears. Surgical repair in rotator cuff tears that include 50% or more of the tendon thickness is the accepted practice in the following failure of nonoperative treatment. In the surgical procedure, acromioplasty is known as a long-established component and used to modify the detrimental acromion morphology, which accounts for rotator cuff tearing. A range of trials has been reported that compare the results of surgical procedure with and without acromioplasty in patients undergoing rotator cuff repairs. According to the findings of 15 studies including ~1,500 patients, with mean age 60 years (range 5-80 years) and mean follow-up of 22 months (range 13-26 months) found by searching on Cochrane Register of Controlled Trials databases, Excerpta Medica/Embase, and Medline/PubMed, we revealed that acromioplasty cannot present an impressive effect on patient outcome scores at intermediate and short-term follow-ups. In fact, despite the theoretic advantages of acromioplasty in the setting of PTRCTs, it has reported little or no efficacy on outcomes of postoperative patients.

Efficacy of Extracorporeal Shockwave Therapy on Calcified and Noncalcified Shoulder Tendinosis: A Propensity Score Matched Analysis

Background

Extracorporeal shock wave therapy (ESWT) had been proved to be beneficial in calcific tendinosis; however, the treatment efficacy in noncalcific tendinosis of rotator cuff still remains controversial. The present study was to compare the outcomes ESWT among the noncalcific rotator cuff tendinosis and different types of calcific tendinosis on the basis of similar shoulder functional status.

Methods

A retrospective, comparative study was conducted with the enrollment of 20 patients in each group through propensity score matching in a 1:1:1 ratio from 291 patients who underwent single ESWT for painful shoulder tendinosis. The patients were divided into three groups which included noncalcified tendinosis (NCTS), type I dense calcified tendinosis of shoulder (DCTS), and type II and type III translucent calcified tendinosis of shoulder (TCTS) according to Gartner and Heyer classification. The clinical evaluation included the subjective pain score with visual analog scale (VAS) and functional outcome with Constant and Murley score (CMS).

Results

Twelve months after ESWT, the VAS in TCTS (1.5 ± 2.48) was statistically significant lower than NCTS (2.9 ± 2.86) and DCTS (3.8 ± 2.46) (p=.011). For the functional outcome, the overall CMS was superior in TCTS than the NCTS and DCTS (86.9 ± 19.7 versus 78.7 ± 18.3 and 71.1 ± 17.8, p=.014). Besides, the subscales of pain score, strength, and range of motion in TCTS improved significantly better than NCTS and DCTS. 70% of patients were complaint-free in TCTS group, which was higher than the NCTS group (15%) and DCTS group (25%) (p<0.05).

Conclusion

The present study indicated that the high-dose ESWT posed superior clinical efficacy in type II/III calcification tendinosis rather than type I calcification and noncalcific shoulder tendinosis.

Occupational cranking operations: The scapula perspective

Cranking the landing gear is a common task performed by truck drivers to raise or lower trailers. This task poses a risk to the shoulder joint due to the required forceful exertion and the posture constrained to the hand-handle interface. As a potential occupational risk, there has been no definitive guideline for best practices among truck drivers. An operator can crank perpendicular (frontal) or parallel (sagittal) to the crank rotation. In this laboratory study, the effects of cranking method and resistance on scapular range of motion and shoulder muscle activity were observed in 12 participants. Scapular posture was measured using an optical motion tracking system. EMG was monitored on 16 muscles contributing to shoulder movement. The results show that during frontal cranking, the scapular range of protraction was 28 ± 11.6°, which was more than the sagittal cranking (23 ± 10.4°), indicating a decreased subacromial space and elevated shoulder impingement risk. Seven muscles (all three deltoid muscles, middle trapezius, supraspinatus, infraspinatus, and teres minor) demonstrated that when the crank resistance was low, the front cranking method resulted in lower activity than the side cranking. When the crank resistance was 20 Nm, the muscle activity on these seven muscles was greater when cranking from the front than from the side. Based on these observations, we suggest that when the resistance is low (lowering the trailer) the driver should stand facing the trailer. On the contrary, it is advantageous to stand parallel to the trailer and crank while raising the trailer to apply the full body strength to reduce the shoulder load.

Grade of coracoacromial ligament degeneration as a predictive factor for impingement syndrome and type of partial rotator cuff tear

BACKGROUND

The purpose of this study was to investigate the role of coracoacromial ligament degeneration and specific anatomic parameters in the etiology of partial-thickness rotator cuff tears.

MATERIALS AND METHODS

This study retrospectively assessed 96 patients (mean age, 50.1 years [17-76]; 34 men, 62 women) diagnosed with bursal-side and articular-side rotator cuff tears with a history of failed conservative treatment and persistent shoulder pain who underwent arthroscopic surgery. Video records of the surgery were used to evaluate the type of cuff tear, grade of coracoacromial ligament degeneration, and associated pathologic changes; preoperative magnetic resonance images were used to measure acromioglenoid angle, supraspinatus glenoid angle, and subacromial distance.

RESULTS

Most of the patients with articular-side tears demonstrated grade 0 and grade 1 coracoacromial ligament degeneration, whereas patients with bursal-side tears had grade 1 and grade 2. There was a significant positive correlation between the grade of coracoacromial ligament degeneration and bursal-side partial rotator cuff tears, whereas no correlation was observed with articular-side tears. There was no significant difference between bursal-side and articular-side partial cuff tears regarding acromioglenoid angle, supraspinatus glenoid angle, and subacromial distance.

CONCLUSIONS

Grade 1 and grade 2 coracoacromial ligament degeneration is a strong predictive factor for impingement syndrome in the etiology of bursal-side partial cuff tears and can guide the surgeon to consider ligament release and débridement or acromioplasty in these patients.

Clinical outcomes and prognostic factors depending on implant design in the treatment of proximal humeral fractures: A retrospective study

PURPOSE

We aimed to examine the clinical outcomes of proximal humeral fractures treated with different intramedullary nail shapes.

METHODS

Thirty-seven patients were divided into two groups depending on the implant shape. We also defined F group as a subgroup of fracture classification.

RESULTS

In the F group, the flexion of the shoulder joint was significantly greater in S (mean, 134.6°) than in C groups (mean, 109°) (p = 0.04). The complication rate was significantly larger in the C group (p = 0.04).

CONCLUSIONS

Patients with one kind of fracture and who were treated with straight nails had better outcomes.

Tendinopathy: Update on Pathophysiology

Synopsis Tendinopathy has become the accepted term to describe a spectrum of changes that occur in damaged and/or diseased tendons. Over the past 2 decades, there have been new insights into tendon pathophysiology of relevance to clinicians, including (1) better characterization of the overuse injury process and the resultant structural and functional disruption in chronically painful tendons, (2) improved understanding of the pathomechanics associated with chronic tendon injury, and (3) greater knowledge about the influence of lifestyle factors and drugs on tendon pathology. The implications of these new insights are discussed. J Orthop Sports Phys Ther 2015;45(11):833-841. Epub 21 Sep 2015. doi:10.2519/jospt.2015.5884.

Is acromioplasty necessary in the setting of full-thickness rotator cuff tears? A systematic review

BACKGROUND

The benefits of acromioplasty in treating rotator cuff disease have been debated. We systematically reviewed the literature regarding whether acromioplasty with concomitant coracoacromial (CA) release is necessary for the successful treatment of full-thickness rotator cuff tears.

MATERIALS AND METHODS

We identified randomized controlled trials that reported on patients who underwent rotator cuff repair with or without acromioplasty and used descriptive statistics to summarize the findings.

RESULTS

Four studies fulfilled the inclusion criteria. They reported on 354 patients (mean age, 59 years; range 3-81 years) with a mean follow-up of 22 months (range 12-24 months). There were two level-I and two level-II studies. Two studies compared rotator cuff repair with versus without acromioplasty, and two studies compared rotator cuff repair with versus without subacromial decompression (acromioplasty, CA ligament resection, and bursectomy). The procedures were performed arthroscopically, and the CA ligament was released in all four studies. There were no statistically significant differences in clinical outcomes between patients treated with acromioplasty compared with those treated without acromioplasty.

CONCLUSIONS

This systematic review of the literature does not support the routine use of partial acromioplasty or CA ligament release in the surgical treatment of rotator cuff disease. In some instances, partial acromioplasty and release of the CA ligament can result in anterior escape and worsening symptoms. Further research is needed to determine the optimum method for the operative treatment of full-thickness rotator cuff tears.

LEVEL OF EVIDENCE

Level I, systematic review of level I and II studies.

Rotator cuff biology and biomechanics: a review of normal and pathological conditions

The glenohumeral joint is a complex anatomic structure commonly affected by injury such as tendinopathy and rotator cuff tears. This review presents an up-to-date overview of research on tendon biology and structure, shoulder joint motion and stability, tendon healing, and current and potential future repair strategies. Recent studies have provided information demonstrating the serious impact on uninjured tissues after a rotator cuff tear or other cause of altered shoulder joint mechanics. Another major focus of recent research is biological augmentation of rotator cuff repair with the goal of successfully reinstating normal tendon-to-bone structure. To effectively treat shoulder pathologies, clinicians need to understand normal tendon biology, the healing process and environment, and whole shoulder stability and function.

Evidence-based practice: best imaging practice in musculoskeletal disorders

As musculoskeletal disorders are a common cause of emergency department visits in the United States, it is vital for nurses and nurse practitioners to understand the decision rules for ordering imaging tests when triaging patients with musculoskeletal complaints. Proper knowledge and command of selecting the most appropriate imaging for these frequent emergency department presentations will help reduce costs, decrease ionizing radiation exposure, and increase patient throughput. This article reviews the current evidence-based literature for musculoskeletal imaging in the emergency department and discusses the epidemiology, etiology, management, and prevention of the most common musculoskeletal disorders.

Cyclic strain alters the expression and release of angiogenic factors by human tendon cells

Angiogenesis is associated with the tissue changes underlying chronic overuse tendinopathy. We hypothesized that repetitive, cyclic loading of human tendon cells would lead to increased expression and activity of angiogenic factors. We subjected isolated human tendon cells to overuse tensile loading using an in vitro model (1 Hz, 10% equibiaxial strain). We found that mechanically stimulated human tendon cells released factors that promoted in vitro proliferation and tube formation by human umbilical vein endothelial cells (HUVEC). In response to cyclic strain, there was a transient increase in the expression of several angiogenic genes including ANGPTL4, FGF-2, COX-2, SPHK1, TGF-alpha, VEGF-A and VEGF-C, with no change in anti-angiogenic genes (BAI1, SERPINF1, THBS1 and 2, TIMP1-3). Cyclic strain also resulted in the extracellular release of ANGPTL4 protein by tendon cells. Our study is the first report demonstrating the induction of ANGPTL4 mRNA and release of ANGPTL4 protein in response to cyclic strain. Tenocytes may contribute to the upregulation of angiogenesis during the development of overuse tendinopathy.

A randomised controlled feasibility study investigating the use of eccentric and concentric strengthening exercises in the treatment of rotator cuff tendinopathy

Objectives:

To conduct a feasibility study to compare concentric and eccentric rotator cuff strengthening exercises for rotator cuff tendinopathy.

Methods:

A total of 11 patients with rotator cuff tendinopathy who were on the waiting list for arthroscopic subacromial decompression surgery were randomised to perform eccentric rotator cuff strengthening exercises, concentric strengthening exercises or no exercises. Patients were evaluated in terms of levels of pain and function using the Oxford Shoulder Score and a Visual Analogue Scale initially, at 4 weeks and at 8 weeks.

Results:

The study design was found to be acceptable to patients and achieved a high level of 86% compliance. The drop-out rate was 0%. Two patients performing eccentric strengthening exercises improved sufficiently to cancel their planned surgery.

Conclusion:

Further research in this area is recommended. The study design was feasible and power calculations have been conducted to aid future research planning.

Posterior glenohumeral joint capsule contracture

Glenohumeral joint posterior capsule contracture may cause shoulder pain by altering normal joint mechanics. Contracture is commonly noted in throwing athletes but can also be present in nonthrowers. The cause of contracture in throwing athletes is assumed to be a response to the high amount of repetitive tensile force placed on the tissue, whereas the mechanism of contracture in nonthrowers is unknown. It is likely that mechanical and cellular processes interact to increase the stiffness and decrease the compliance of the capsule, although the exact processes that cause a contracture have not been confirmed. Cadaver models have been used to study the effect of posterior capsule contracture on joint mechanics and demonstrate alterations in range of motion and in humeral head kinematics. Imaging has been used to assess posterior capsule contracture, although standard techniques and quantification methods are lacking. Clinically, contracture manifests as a reduction in glenohumeral internal rotation and/or cross body adduction range of motion. Stretching and manual techniques are used to improve range of motion and often decrease symptoms in painful shoulders.

Histopathology of rotator cuff tears

The pathogenesis of rotator cuff tears is multifactorial. Tendon abnormalities of the rotator cuff include alteration of collagen fiber structure, tenocytes, cellularity, and vascularity. Ruptured tendons show marked collagen degeneration and disordered arrangement of collagen fibers. Fibroblast population decreases as the size of the tear in the rotator cuff increases. The larger fibroblast population seen in the smaller tears is also actively proliferating and is part of an active reparative process. Inflammatory cell infiltrate correlates inversely to rotator cuff tear size in the torn supraspinatus tendon samples, with larger tears showing a marked reduction in all cell types. As tear size increase, there is also a progressive decrease in the number of blood vessels. Whether rotator cuff tear heals spontaneously is an important pathologic and clinical question. Histologic changes indicative of repair and inflammation lead to consider biological options in addition to biomechanical treatment of the rotator cuff tears.

Early response to tendon fatigue damage accumulation in a novel in vivo model

This study describes the development and application of a novel rat patellar tendon model of mechanical fatigue for investigating the early in vivo response to tendon subfailure injury. Patellar tendons of adult female Sprague-Dawley rats were fatigue loaded between 1-35N using a custom-designed loading apparatus. Patellar tendons were subjected to Low-, Moderate- or High-level fatigue damage, defined by grip-to-grip strain measurement. Molecular response was compared with that of a laceration-repair injury. Histological analyses showed that progression of tendon fatigue involves formation of localized kinked fiber deformations at Low damage, which increased in density with presence of fiber delaminations at Moderate damage, and fiber angulation and discontinuities at High damage levels. RT-PCR analysis performed at 1- and 3-day post-fatigue showed variable changes in type I, III and V collagen mRNA expression at Low and Moderate damage levels, consistent with clinical findings of tendon pathology and were modest compared with those observed at High damage levels, in which expression of all collagens evaluated were increased markedly. In contrast, only type I collagen expression was elevated at the same time points post-laceration. Findings suggest that cumulative fatigue in tendon invokes a different molecular response than laceration. Further, structural repair may not be initiated until reaching end-stage fatigue life, where the repair response may unable to restore the damaged tendon to its pre-fatigue architecture.

Pathogenesis of tendinopathies: inflammation or degeneration?

The intrinsic pathogenetic mechanisms of tendinopathies are largely unknown and whether inflammation or degeneration has the prominent role is still a matter of debate. Assuming that there is a continuum from physiology to pathology, overuse may be considered as the initial disease factor; in this context, microruptures of tendon fibers occur and several molecules are expressed, some of which promote the healing process, while others, including inflammatory cytokines, act as disease mediators. Neural in-growth that accompanies the neovessels explains the occurrence of pain and triggers neurogenic-mediated inflammation. It is conceivable that inflammation and degeneration are not mutually exclusive, but work together in the pathogenesis of tendinopathies.

The association of scapular kinematics and glenohumeral joint pathologies

There is a growing body of literature associating abnormal scapular positions and motions, and, to a lesser degree, clavicular kinematics with a variety of shoulder pathologies. The purpose of this manuscript is to (1) review the normal kinematics of the scapula and clavicle during arm elevation, (2) review the evidence for abnormal scapular and clavicular kinematics in glenohumeral joint pathologies, (3) review potential biomechanical implications and mechanisms of these kinematic alterations, and (4) relate these biomechanical factors to considerations in the patient management process for these disorders. There is evidence of scapular kinematic alterations associated with shoulder impingement, rotator cuff tendinopathy, rotator cuff tears, glenohumeral instability, adhesive capsulitis, and stiff shoulders. There is also evidence for altered muscle activation in these patient populations, particularly, reduced serratus anterior and increased upper trapezius activation. Scapular kinematic alterations similar to those found in patient populations have been identified in subjects with a short rest length of the pectoralis minor, tight soft-tissue structures in the posterior shoulder region, excessive thoracic kyphosis, or with flexed thoracic postures. This suggests that attention to these factors is warranted in the clinical evaluation and treatment of these patients. The available evidence in clinical trials supports the use of therapeutic exercise in rehabilitating these patients, while further gains in effectiveness should continue to be pursued.

LEVEL OF EVIDENCE

Level 5.

A stochastic analysis of glenoid inclination angle and superior migration of the humeral head

BACKGROUND

Superior glenoid inclination, which is a relatively upward facing of the glenoid in the plane of the scapula, has been associated with rotator cuff pathology. Increased glenoid inclination may cause superior humeral head migration, which can cause impingement of the supraspinatus tendon. The purpose of this study was to test the hypothesis that inclination angle affects the probability of superior humeral head migration.

METHODS

A three-dimensional model of the glenohumeral joint was developed in which muscle forces were modeled as random variables. Monte Carlo simulation was used to compute the probability that the glenohumeral reaction force was directed such that superior humeral head migration should occur. An electromyogram-driven model was used to estimate shoulder muscle forces in healthy volunteers performing arm elevation.

FINDINGS

The model predicted that the probability of superior humeral head migration increased as glenoid inclination angle was increased. This finding was independent of the assumed shape of the muscle force probability distributions.

INTERPRETATION

The results support the theory that glenoid inclination may be a risk factor for rotator cuff pathology.

Rat supraspinatus tendon expresses cartilage markers with overuse

The goals of this study were to investigate the response of the rat supraspinatus tendon to overuse at the molecular level using transcriptional profiling, and to identify potential markers of tendinopathy. Adult rats were subjected to an overuse protocol that consists of downhill running (10% grade) at 17 m/min for 1 h/day, 5 days/week, for a total of either 1, 2, or 4 weeks. Another group of rats served as nonrunning time 0 controls. Transcriptional profiling was performed on the supraspinatus and patellar tendons using an Affymetrix rat genome array. A gene was considered to be differentially expressed if the p value from an ANOVA test was less than 0.01 and the difference between runners and controls was at least twofold at any time point. The supraspinatus tendon had increased expression of well-known cartilage genes such as col2a1, aggrecan, and sox9. These genes were not regulated in the patellar tendon, an internal comparator. Few genes associated with inflammation, or angiogenesis, were differentially expressed, and no significant change in the regulation of matrix metalloproteinases was detected. The results of this study suggest that by expressing more cartilage genes, the tendon is converting toward a fibrocartilage phenotype as a result of the repetitive loading and repeated compression of the tendon as it passes through the acromial arch.

3D kinematics of the glenohumeral joint during abduction motion: an ex vivo study

The clinical tolerance of rotator cuff tears is extremely variable, so the question is, what is the role of the deltoid in the shoulder stability? First of all, ex vivo experiments are necessary to analyse its effect. The aims of this study were: (1) to propose a testing protocol to measure the glenohumeral joint kinematics during the abduction motion by pulling on the deltoid without constraining the humerus and (2) to evaluate the repeatability of the 3D measurements. Six fresh-frozen anatomic specimens were tested. The kinematics follow-up of the osseous parts was carried out using an optoelectronic system (Polaris((R)), NDI, Canada). The abduction motion is realized by the pulling on anterior and medium fibers of the deltoid. For a 25 mm displacement, the range of motion: for the abduction was 24 degrees to 30.5 degrees , for the flexion was 1.5 degrees to -30.5 degrees (extension), for the medio-lateral rotation was 12 degrees (lateral rotation) to -5 degrees (medial rotation). For a displacement of the whole acromion-clavicle between 0 and 25 mm, the three humeral head translations were less than 5 mm. The three rotations and three translations were (with SD 95%): abduction: 0.5 degrees , flexion: 1 degrees , medio-lateral rotation: 1.5 degrees , three translations: 0.5 mm. The results showed a very high repeatability of the values. Results suggest that the deltoid alone can realize a motion of lateral elevation with a good stability in the glenohumeral joint as shown by the slight translation motion of the head and the value reproducibility. The protocol can be used to validate a finite element model of the glenohumeral joint.

Interleukin-6-induced activation of signal transducer and activator of transcription-3 in ruptured rotator cuff tendon

The aim of this study was to examine interleukin-6 production and the activation of signal transducer and activator of transcription-3 (STAT3) in ruptured rotator cuff tendon. Specimens of ruptured rotator cuff tendons were analysed using real-time reverse transcriptase polymerase chain reaction, Western blotting and immunohistochemistry. Specimens of co-existing inflammatory subacromial synovia were examined for comparison. The level of interleukin-6 messenger RNA was increased in ruptured rotator cuff tendon as well as in subacromial synovium. Western blot analysis showed constitutive production of activated, phosphorylated STAT3 in ruptured rotator cuff tendon and co-existing subacromial synovium. Immunohistochemical examination detected cells producing interleukin-6, interleukin-6 receptor and phosphorylated STAT3 in ruptured rotator cuff tendon, mainly in proliferative vessels and, to a lesser extent, in tendon fibroblasts around the vessels. This study demonstrates that activation of STAT3 induced by interleukin-6 is promoted mainly by proliferative vessels in ruptured rotator cuff tendon.

Upper-extremity pain disorders in breast cancer

Upper-extremity pain is a common and debilitating problem for patients with breast cancer. Although there is considerable literature describing symptoms, little is available on the specific disorders responsible for pain and debility in these patients. Cervical radiculopathy, brachial plexopathy, neuropathy, rotator cuff tendonitis, adhesive capsulitis, epicondylitis, postmastectomy syndrome, swelling, and bone metastases are among the common disorders responsible for upper-extremity pain in breast cancer patients.

OVERALL ARTICLE OBJECTIVE

To discuss common upper-extremity pain disorders in patients with breast cancer.

Current concepts in the management of tendon disorders

Primary disorders of tendons are common and constitute a high proportion of referrals to rheumatologists. Certain tendons are particularly vulnerable to degenerative pathology; these include the Achilles, patella, elements of the rotator cuff, forearm extensors, biceps brachi and tibialis posterior tendons. Disorders of these tendons are often chronic and can be difficult to manage successfully in the long term. Significant advances have been made in understanding the pathophysiology of these conditions. Histopathological evidence, together with advances in imaging techniques, has made us more appreciative of the degenerative (rather that inflammatory) nature of these conditions. Additionally the presence of neovascularization is now well-recognized in long-standing tendinopathy. We review the mechanical, vascular and developing neural theories that attempt to explain the aetiology of degenerative tendinopathy. We also explore theories of why specific tendons (such as the Achilles and supraspinatus tendons) are particularly prone to degenerative pathology. Traditionally, treatments have placed a heavy emphasis on anti-inflammatory strategies, which are often inappropriate. Recently, however, significant advances in the practical management of tendon disorders have been made. In particular the advent of 'eccentric loading' training programmes has revolutionized the treatment of Achilles tendinopathy in some patients. This concept is currently being extended to include other commonly injured tendons. Other current treatments are reviewed, as are potential future treatments.

IGF-I activates PKB and prevents anoxic apoptosis in Achilles tendon cells

Anoxia and apoptosis are both implicated in chronic tendon pathology, however the influence of anoxia on the viability of tendon cells is not known. The objectives of the current study were to (i) investigate the effect of oxygen withdrawal on the viability of porcine Achilles tendon cells (ATCs), and (ii) examine the ability of IGF-I, a factor with known regenerative properties in tendon, to prevent ATC death. Cultured ATCs were enclosed in an anaerobic chamber. The mechanism of cell death was examined by flow cytometry of ATCs double labeled with Annexin-V and propidium iodide (PI). Caspase activity was determined by a fluorometric assay, and nuclear morphology was examined by Hoechst staining. The cell death induced by anoxia was time-dependent, and was characterized by phosphatidylserine exposure on the outer membrane, caspase activation and DNA fragmentation. Death was inhibited by the addition of IGF-I in a dose-dependent manner. The ability of IGF-I to activate the pro-survival PKB pathway in ATCs was inhibited by LY294002, indicating the importance of PI3K in the response of ATCs to IGF-I. These data suggest that cell death induced by lack of oxygen is predominantly apoptotic and can be prevented by pro-survival IGF-I signaling. This mechanism may contribute to the beneficial effect of IGF-I on tendon.

Rotator cuff injuries and treatment

Rotator cuff problems are among the most commonly encountered disorders of the shoulder, and are commonly seen by primary care physicians. Their exact mechanism for susceptibility to injury remains unclear; however, with an understanding of the shoulder's anatomy and biomechanics, we are better able to treat the insults incurred on the cuff. Early recognition, proper treatment, and appropriate follow-up may expedite healing and prevent the occurrence of further injury or complications.