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.

Objective: This meta-analysis aims to compare the minimally invasive percutaneous plate osteosynthesis (MIPPO) versus intramedullary nail (IMN) for distal tibial fractures. The comparison focuses on postoperative functional outcomes, complication rates, time to fracture union, and other relevant clinical indicators. Methods: A comprehensive computerized search was conducted across PubMed, Web of Science, Cochrane Library, and Embase, covering all available publications up to 4 August 2024. Two independent researchers assessed the quality of the selected studies using predefined inclusion and exclusion criteria. Key demographic and clinical data, such as patient gender, age, surgery duration, postoperative functional outcomes, and complication rates, were collected from the included studies. Statistical analysis was performed using Review Manager 5.3. Results: A total of 23 studies, involving 1742 patients, were included in the meta-analysis, with 858 patients treated using MIPPO and 884 patients treated with IMN. The pooled data revealed that patients who underwent IMN experienced a shorter time to bone union, along with a lower incidence of infection, ankle stiffness, and soft tissue complications. Conversely, MIPPO demonstrated advantages in reducing the rates of malalignment and anterior knee pain. No significant differences were observed between the two methods in terms of functional scores, delayed or non-union rates, and overall complication rates. Conclusions: IMN was found to promote faster bone union compared to MIPPO with high heterogeneity but no difference was found in function score between the two groups. Although both techniques exhibited similar overall complication rates, the specific types of complications varied between the two. The MIPPO group showed lower rate of malalignment rate and knee pain, whereas the IMN group had fewer infections, ankle stiffness, and soft tissue issues. No significant difference was noted in the rates of delayed or non-union. The choice of surgical method may depend on individual patient conditions, with different techniques potentially better suited for reducing the risk of certain complications. Further clinical studies are needed to better understand patient preferences and optimize treatment strategies for distal tibial fractures.

Introduction: Promoting muscle regeneration through stem cell therapy has potential risks. We investigated the effect of umbilical cord mesenchymal stem cells (UMSCs) Exosomes (Exo) Follistatin on muscle regeneration.Material and methods: The Exo was derived from UMSCs cells and was utilized to affect the mice muscle injury model and C2C12 cells myotubes atrophy model. The western blot, qRT-PCR and IF were utilized to determine the effects of Exo on the levels of Follistatin, MyHC, MyoD, Myostatin, MuRF1, MAFbx, α-SMA, Collagen I, Smad2, and AKT. In addition, HE and Masson staining were used to assess muscle tissue damage in mice.Results: The level of Follistatin in Exo was significantly higher than that in UMSCs. UMSCs-Exo increased the levels of Follistatin, MyHC, MyoD, and p-Smad2 and decreased the levels of Myostatin, MuRF1, MAFbx, α-SMA, Collagen I, p-AKT, and p-mTOR in mice or C2C12 cells. In addition, UMSCs-Exo decreased levels of inflammation and fibrosis in mice. However, UMSCs-Exo-si-Follistatin reversed the effect of UMSCs-Exo. Transfection of oe-Smad2 up-regulated the protein levels of Collagen I, α-SMA, and changed the ratio of p-Smad2/Smad2 expression to 0.33, and 0.34, 0.73. LY294002 decreased the levels of MyHC, MyoD, and the ratio of p-AKT/ AKT and p-mTOR/mTOR expression to 0.12, 0.17, 0.33, and 0.41, increased the levels of MuRF1 and MAFbx to 0.36 and 0.34.Conclusions: This study demonstrated that Follistatin in UMSCs-Exo inhibits fibrosis and promotes muscle regeneration in mice by regulating Smad and AKT signaling.