Aims. Rotator cuff muscle atrophy and fatty infiltration affect the clinical outcomes of rotator cuff tear patients. However, there is no effective treatment for fatty infiltration at this time. High-intensity interval training (HIIT) helps to activate beige adipose tissue. The goal of this study was to test the role of HIIT in improving muscle quality in a rotator cuff tear model via the β3 adrenergic receptor (β3AR). Methods. Three-month-old C57BL/6 J mice underwent a unilateral rotator cuff injury procedure. Mice were forced to run on a treadmill with the HIIT programme during the first to sixth weeks or seventh to 12th weeks after tendon tear surgery. To study the role of β3AR, SR59230A, a selective β3AR antagonist, was administered to mice ten minutes before each exercise through intraperitoneal injection. Supraspinatus muscle, interscapular brown fat, and inguinal subcutaneous white fat were harvested at the end of the 12th week after tendon tear and analyzed biomechanically, histologically, and biochemically. Results. Histological analysis of supraspinatus muscle showed that HIIT improved muscle atrophy, fatty infiltration, and contractile force compared to the no exercise group. In the HIIT groups, supraspinatus muscle, interscapular brown fat, and inguinal subcutaneous white fat showed increased expression of tyrosine hydroxylase and uncoupling protein 1, and upregulated the β3AR thermogenesis pathway. However, the effect of HIIT was not present in mice injected with SR59230A, suggesting that HIIT affected muscles via β3AR. Conclusion. HIIT improved supraspinatus muscle quality and function after rotator cuff tears by activating systemic sympathetic nerve fibre near adipocytes and β3AR. Cite this article: Bone Joint Res 2023;12(8):455–466

Aims. Rotator cuff tear (RCT) is the leading cause of shoulder pain, primarily associated with age-related tendon degeneration. This study aimed to elucidate the potential differential gene expressions in tendons across different age groups, and to investigate their roles in tendon degeneration. Methods. Linear regression and differential expression (DE) analyses were performed on two transcriptome profiling datasets of torn supraspinatus tendons to identify age-related genes. Subsequent functional analyses were conducted on these candidate genes to explore their potential roles in tendon ageing. Additionally, a secondary DE analysis was performed on candidate genes by comparing their expressions between lesioned and normal tendons to explore their correlations with RCTs. Results. We identified 49 genes in torn supraspinatus tendons associated with advancing age. Among them, five age-related genes showed DE in lesioned tendons compared to normal tendons. Functional analyses and previous studies have highlighted their specific enrichments in biological functions, such as muscle development (e.g. myosin heavy chain 3 (MYH3)), transcription regulation (e.g. CCAAT enhancer binding brotein delta (CEBPD)), and metal ion homeostasis (e.g. metallothionein 1X (MT1X)). Conclusion. This study uncovered molecular aspects of tendon ageing and their potential links to RCT development, offering insights for targeted interventions. These findings enhance our understanding of the mechanisms of tendon degeneration, allowing potential strategies to be made for reducing the incidence of RCT. Cite this article: Bone Joint Res 2024;13(9):474–484

Aims. Rotator cuff (RC) tears are common musculoskeletal injuries which often require surgical intervention. Noninvasive pulsed electromagnetic field (PEMF) devices have been approved for treatment of long-bone fracture nonunions and as an adjunct to lumbar and cervical spine fusion surgery. This study aimed to assess the effect of continuous PEMF on postoperative RC healing in a rat RC repair model. Methods. A total of 30 Wistar rats underwent acute bilateral supraspinatus tear and repair. A miniaturized electromagnetic device (MED) was implanted at the right shoulder and generated focused PEMF therapy. The animals’ left shoulders served as controls. Biomechanical, histological, and bone properties were assessed at three and six weeks. Results. Extension of the tendon from preload to the maximum load to failure was significantly better in the PEMF-treated shoulders at three weeks compared to controls (p = 0.038). The percentage strain was significantly higher in the PEMF group at both timepoints (p = 0.037). Collagen organization was significantly better (p = 0.034) as was tissue mineral density in the PEMF-treated group at three weeks (p = 0.028). Tendon immunohistochemistry revealed a prominent increase in type I collagen at the repair site at three weeks following continuous PEMF treatment compared with controls. None of the other tested parameters differed between the groups. Conclusion. MED-generated PEMF may enhance early postoperative tendon-to-bone healing in an acute rat supraspinatus detachment and repair model. Superior biomechanical elasticity parameters together with better collagen organization suggest improved RC healing. Cite this article: Bone Joint Res 2021;10(5):298–306

Aims

Rotator cuff (RC) injuries are characterized by tendon rupture, muscle atrophy, retraction, and fatty infiltration, which increase injury severity and jeopardize adequate tendon repair. Epigenetic drugs, such as histone deacetylase inhibitors (HDACis), possess the capacity to redefine the molecular signature of cells, and they may have the potential to inhibit the transformation of the fibro-adipogenic progenitors (FAPs) within the skeletal muscle into adipocyte-like cells, concurrently enhancing the myogenic potential of the satellite cells.

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

Aims

This study aimed to define the histopathology of degenerated humeral head cartilage and synovial inflammation of the glenohumeral joint in patients with omarthrosis (OmA) and cuff tear arthropathy (CTA). Additionally, the potential of immunohistochemical tissue biomarkers in reflecting the degeneration status of humeral head cartilage was evaluated.

Objectives

Indocyanine green (ICG) fluorescence angiography is an emerging technique that can provide detailed anatomical information during surgery. The purpose of this study is to determine whether ICG fluorescence angiography can be used to evaluate the blood flow of the rotator cuff tendon in the clinical setting.

Objectives

The aim of this study was to determine whether there is any significant difference in temporal measurements of pain, function and rates of re-tear for arthroscopic rotator cuff repair (RCR) patients compared with those patients undergoing open RCR.