Translational therapy from preclinical animal models for muscle degeneration after rotator cuff injury

Studying intramuscular fat deposition and muscle regeneration: insights from a comparative analysis of mouse strains, injury models, and sex differences

Intramuscular fat (IMAT) infiltration, pathological adipose tissue that accumulates between muscle fibers, is a shared hallmark in a diverse set of diseases including muscular dystrophies and diabetes, spinal cord and rotator cuff injuries, as well as sarcopenia. While the mouse has been an invaluable preclinical model to study skeletal muscle diseases, they are also resistant to IMAT formation. To better understand this pathological feature, an adequate pre-clinical model that recapitulates human disease is necessary. To address this gap, we conducted a comprehensive in-depth comparison between three widely used mouse strains: C57BL/6J, 129S1/SvlmJ and CD1. We evaluated the impact of strain, sex and injury type on IMAT formation, myofiber regeneration and fibrosis. We confirm and extend previous findings that a Glycerol (GLY) injury causes significantly more IMAT and fibrosis compared to Cardiotoxin (CTX). Additionally, females form more IMAT than males after a GLY injury, independent of strain. Of all strains, C57BL/6J mice, both females and males, are the most resistant to IMAT formation. In regard to injury-induced fibrosis, we found that the 129S strain formed the least amount of scar tissue. Surprisingly, C57BL/6J of both sexes demonstrated complete myofiber regeneration, while both CD1 and 129S1/SvlmJ strains still displayed smaller myofibers 21 days post injury. In addition, our data indicate that myofiber regeneration is negatively correlated with IMAT and fibrosis. Combined, our results demonstrate that careful consideration and exploration are needed to determine which injury type, mouse model/strain and sex to utilize as preclinical model especially for modeling IMAT formation.

Aging-Related Rotator Cuff Tears: Molecular Mechanisms and Implications for Clinical Management

Shoulder pain and disabilities are prevalent issues among the elderly population, with rotator cuff tear (RCT) being one of the leading causes. Although surgical treatment has shown some success, high postoperative retear rates remain a great challenge, particularly in elderly patients. Aging-related degeneration of muscle, tendon, tendon-to-bone enthesis, and bone plays a critical role in the development and prognosis of RCT. Studies have demonstrated that aging worsens muscle atrophy and fatty infiltration, alters tendon structure and biomechanical properties, exacerbates enthesis degeneration, and reduces bone density. Although recent researches have contributed to understanding the pathophysiological mechanisms of aging-related RCT, a comprehensive systematic review of this topic is still lacking. Therefore, this article aims to present a review of the pathophysiological changes and their clinical significance, as well as the molecular mechanisms underlying aging-related RCT, with the goal of shedding light on new therapeutic approaches to reduce the occurrence of aging-related RCT and improve postoperative prognosis in elderly patients.

Postoperative Antiosteoporotic Treatment with Zoledronic Acid Improves Rotator Cuff Healing but Does Not Improve Outcomes in Female Patients with Postmenopausal Osteoporosis: A Prospective, Single-Blinded, Randomized Study

PURPOSE

To investigate the effect of the antiosteoporotic agent zoledronic acid (ZA) on rotator cuff healing and clinical outcomes in patients with postmenopausal osteoporosis.

METHODS

We prospectively enrolled 138 female patients with postmenopausal osteoporosis who were scheduled to undergo arthroscopic rotator cuff repair (ARCR) from March 2020 to March 2021. Patients were randomly allocated to the ZA group (ARCR followed by intravenous ZA infusions at postoperative Day 1 and 1 year later) and the control group (ARCR alone). All patients were followed up for 24 months. Tendon healing was evaluated by ultrasonography at 6 weeks and 24 months after surgery. The American Shoulder and Elbow Surgeons (ASES) score, Western Ontario Rotator Cuff (WORC) index, and Numeric Rating Scale (NRS) for pain were recorded at each follow-up, and the minimal clinically important difference (MCID) was calculated.

RESULTS

A total of 124 patients were included in the final analysis, 61 in the ZA group and 63 in the control group. There was no statistically significant difference in participant characteristics between the 2 groups. The ZA group had a significantly higher tendon healing rate than the control group at 2 years after surgery (odds ratio = 5.0; 95% confidence interval [CI], 1.4-18.7; P = .014). Regarding clinical outcomes, 100% of patients exceeded the MCID in both groups, and no significant differences were found at 2 years after surgery between the 2 groups (ASES: 2.5 [95% CI, -2.2 to 7.2; P = .291]; WORC index: 4.5 [95% CI, -0.117 to 9.117; P = .056]; NRS: -0.1 [95% CI, -0.3 to 0.1; P = .394]).

CONCLUSIONS

Antiosteoporotic treatment with ZA reduced the retear rate but did not significantly influence the clinical outcomes after ARCR in female patients with postmenopausal osteoporosis. Outcomes of ARCR showed good results in both groups and exceeded the MCID.

LEVEL OF EVIDENCE

Level I, randomized controlled trial.

Clinical effects of sodium hyaluronate combined with platelet-rich plasma injection on rotator cuff injury in arthroscopic repair

Objective

Rotator cuff injury is one prevalent shoulder condition that often leads to pain and dysfunction. The study explored the clinical effects of sodium hyaluronate combined with platelet-rich plasma (PRP) injection on rotator cuff injury in arthroscopic repair.

Methods

A total of 92 cases with rotator cuff injury were randomly divided into the control group (n = 46, treated with shoulder arthroscopy repair combined with subacromial space injection of sodium hyaluronate) and the experimental group (n = 46, treated with subacromial space injection of autologous PRP on the basis of the treatment in the control group). Visual analogue scale (VAS), Constant-Murley scale (CMS), University of California, Los Angeles (UCLA), American Shoulder and Elbow Society (ASES), and quality of life (QOL) scores, as well as complications were compared in the two groups before surgery and at 3 and 6 months after surgery. Shoulder range of motion (ROM) was measured before and after surgery.

Results

VAS scores of patients in the two groups at 3 and 6 months after surgery were lower than those before surgery, and the VAS scores of patients in the experimental group at 3 and 6 months after surgery were much lower than those in the control group (all P < 0.05). The scores of CMS, UCLA, ASES, and QOL, and shoulder ROM in both groups at 3 and 6 months after surgery were higher than those before surgery, and these shoulder joint function scores, QOL and shoulder ROM in the experimental group at 3 and 6 months after surgery were higher than those in the control group (all P < 0.05). No statistically significant difference presented in the incidence of complications between the two groups (P > 0.05).

Conclusion

Arthroscopic rotator cuff repair and sodium hyaluronate combined with PRP injection can effectively reduce pain symptoms, improve shoulder joint function and shoulder ROM, and improve QOL in patients with rotator cuff injury.

Intermittent fasting promotes repair of rotator cuff injury in the early postoperative period by regulating the gut microbiota

Background

The repair of rotator cuff injury is affected by lifestyle and metabolic factors. Intermittent fasting (IF) can promote repair of damaged tissue by regulating intestinal flora, which provides an idea of therapy for rotator cuff injury. The aim of this study was to investigate the effects of fasting on rotator cuff repair after injury, and the role of intestinal flora or a single strain in this process.

Methods

Mice underwent rotator cuff injury were treated with intermittent fasting or fed ad libitum. Fasting began one month before surgery and continued until euthanasia. Fresh feces were collected at 2 weeks before surgery, on the day of surgery, and 2, 4, 8 weeks postoperatively for 16S rRNA microbiome sequencing. Supraspinatus tendon-humerus ​(SSTH) complex was collected at 2, 4 and 8 weeks after surgery. Live parabacteroides distasonis (Parabacteroides distasonis) was used for repair of rotator cuff injury, with equal amount of pasteurized P. distasonis (KPD) or sterile anaerobic phosphate buffer saline (PBS) as control. Biomechanical, radiological, histological analysis were used to assess the effect of rotator cuff repair.

Results

Biomechanical, radiological and histological analysis indicated that intermittent fasting significantly promoted the repair of rotator cuff injury in the early postoperative period (P ＜ 0.05), but significantly inhibited the repair of rotator cuff injury at 4 weeks postoperatively (P ＜ 0.05). 16S rRNA Microbiome sequencing result showed that P. distasonis was the species with the most obvious changes in intestinal flora of mice after fasting. The results of tensile test, X-ray analysis and histological analysis indicated that the live P. distasonis (LPD) significantly impaired the biomechanical properties, bone regeneration and fibrocartilage regeneration of enthesis postoperatively (P ＜ 0.05).

Conclusion

Intermittent fasting promoted repair of rotator cuff injury in the early postoperative period by regulating the gut microbiota, in which P. distasonis played an important role.

The translational potential of this article

Intermittent fasting (IF) may be a beneficial lifestyle for the repair of rotator cuff injury in the early postoperative period in clinical, and the influence of a certain strain on the repair of rotator cuff injury may also provide an idea for the treatment of rotator cuff injury in the future.

Arthroscopic therapy of rotator cuff diseases: A bibliometric study of the past 2 decades (2002–2021)

Purpose

Rotator cuff diseases, as a common cause of shoulder pain and disability, have seriously affected the patients' daily life. Rotator cuff repair techniques have been a hot topic in the arthroscopic therapy field. Our study was to use bibliometrics analysis to clarify the current status and research trends in the field of arthroscopic therapy of rotator cuff diseases.

Methods

The publications relating to arthroscopic therapy of rotator cuff diseases published from 2001 to 2021 were obtained from the Web of Science Core Collection (WoSCC) database. The R software and VOSviewer software were used for the cross-sectional bibliometric and scientometric analysis.

Results

A total of 4,567 publications about arthroscopic therapy of rotator cuff diseases published between 2002 and 2021 retrieved from the WoSCC database were analyzed in our study. The results showed that the United States made the largest contribution to this field. The most relevant institutions were Seoul National University, Rush University, and Hospital for Special Surgery. Stephen S Burkhart was the most relevant researcher in this field with the largest number of publications, as well as the highest H-index and G-index. The journal ARTHROSCOPY contributed the largest number of publications in the past 2 decades. Considering the H-index and G-index, ARTHROSCOPY was also the journal with the largest impact in this field.

Conclusions

Arthroscopic Therapy of Rotator Cuff Diseases Related research presented a rising trend in the past 2 decades. The United States can be regarded as the leader because of its huge contributions to this field. The journal ARTHROSCOPY published the largest number of publications in this field. It can be predicted that research about advanced arthroscopic techniques and postoperative pain management of patients with rotator cuff diseases will be the next research hotspots in the following years.