Differentiation Ability of Tendon-Derived Stem Cells and Histological Characteristics of Rotator Cuff Remnant on the Greater Tuberosity Degenerated With Age and Chronicity

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.

Outcomes After Combined Remnant Preservation and Bone Marrow Stimulation for Acute Rotator Cuff Tears

Background

Both remnant preservation (RP) and bone marrow stimulation (BMS) enhance the healing potential of the repaired rotator cuff by improving the biological milieu of the tendon-bone interface.

Purpose

To evaluate the clinical and imaging outcomes of arthroscopic rotator cuff repair using a combined RP-BMS technique in patients with acute rotator cuff tears.

Study Design

Cohort study; Level of evidence, 3.

Methods

Between January 2016 and June 2019, a total of 56 patients were diagnosed with acute rotator cuff tears; 29 patients underwent conventional repair (group 1), and 27 patients underwent RP-BMS (group 2). At a minimum follow-up period of 2 years, the authors compared clinical outcomes with the University of California-Los Angeles; Constant; American Shoulder and Elbow Surgeons; and pain visual analog scale scores as well as shoulder range of motion. Tendon integrity and retear were assessed on magnetic resonance imaging according to the Sugaya classification (intact, grades 1-3; retear, grades 4-5). Between-group comparisons were conducted using the Student t test or Mann-Whitney U test for continuous variables and the Pearson chi-square test or Fisher exact test for categorical variables.

Results

In both groups, patients had significant preoperative to postoperative improvement on all clinical outcome measures (P = .001 for all). Shoulder abduction in group 2 was significantly greater compared with group 1 at the postoperative 3-month (107.37° ± 8.32° vs 95.44° ± 8.78°; P = .001), 6-month (155.25° ± 10.02° vs 144.72° ± 9.28°; P = .001), and final (165.15° ± 9.17° vs 158.31° ± 8.01°; P = .021) follow-ups. At the final follow-up, significantly more patients in group 2 had intact tendons (Sugaya grades 1-3) compared with group 1 (P = .015), and the tendon retear rate was lower in group 2 (1/27; 3.70%) than in group 1 (7/29; 24.14%) (P = .033).

Conclusion

Both surgical techniques led to satisfactory clinical outcomes, but shoulder abduction was greater after the RP-BMS technique compared with conventional repair. RP-BMS may be an alternative surgical technique to improve tendon integrity and retear rates after the repair of acute rotator cuff tears.

Healing of Ligaments and Tendons: Tissue Engineering and Models

The aim of this Special Issue is to summarize the latest developments in tendon/ligament research and tissue engineering (TE), providing helpful approaches for future tendon/ligament reconstruction (Figure 1) [...].

Editorial Commentary: Tendon-Derived Stem Cells Are in the Rotator Cuff Remnant and Decline With Age and Tear Chronicity-But the Clinical Relevance Is Not Known

The presence of tendon-derived stem cells (TDSCs) and progenitor cells in tendon tissue has been established previously. These cells are part of the mesenchymal adult stem cell line, are multipotent, and can differentiate into several mesenchymal cell lines: osteogenic, chondrogenic, adipogenic, and tenogenic. Mechanical loading may play an important role in the differentiation process and regulates cell differentiation via several signaling pathways. TDSCs can therefore differentiate into several tissues, and the potential for chondrogenic and osteogenic differentiation may be beneficial in tendon-bone regeneration. TDSCs are present in the tendon stumps, and numerous tests have shown that these cells are alive and have the potential to differentiate. Age is a predictor of TDSC activity, and in patients older than 60 years, cell viability and the potential to differentiate are reduced. Despite the theoretical potential that TDSCs may have for tendon healing and improved function, the potential for clinical applications is unclear.