The Fate of the Shoulder Post Rotator Cuff Repair: Biomechanical Properties of the Supraspinatus Tendon and Surrounding Structures

Background: Rotator cuff injuries, particularly involving the supraspinatus tendon, are common among individuals engaged in overhead activities and can lead to significant complications and loss of shoulder function. Understanding the biomechanical properties of the supraspinatus tendon and surrounding structures following repair is crucial for optimizing treatment strategies. The healing process after rotator cuff repair often results in changes to the mechanical environment of the shoulder that can affect outcomes. The aim of this study is to investigate how different types of rotator cuff tears impact the biomechanical properties of the supraspinatus tendon and its surrounding structures, providing insights that may guide clinical decision-making. Methods: This study employed finite element analysis (FEA) to assess the biomechanical properties of the supraspinatus tendon under various conditions. Six fresh-frozen cadaveric specimens were analyzed to create three-dimensional models representing low-grade and high-grade tears from both articular and bursal sides. The models were subjected to simulated loading conditions to evaluate changes in strain, failure load, and modulus of elasticity across different types of tears. The analysis focused on comparing mechanical properties between articular side tears and bursal side tears to determine their sensitivity to progression and outcomes of surgical intervention. Results: The analysis revealed significant differences in the mechanical properties of the supraspinatus tendon based on the type and severity of the tear. Bursal side tears exhibited lower failure loads and moduli compared to articular side tears, indicating a greater risk for tear progression. Specifically, high-grade tears on the bursal side showed a ۴۲.۵% reduction in failure load and a ۵۰.۵% decrease in modulus compared to their low-grade counterparts. In contrast, high-grade articular side tears demonstrated a ۲۲.۶% reduction in failure load and a ۴۰.۸% decrease in modulus compared to low-grade tears. These findings indicate that bursal side tears are mechanically weaker and more susceptible to further injury under stress, underscoring the need for cautious management strategies for this type of injury. Conclusion: This study highlights the importance of understanding the biomechanical changes that occur after rotator cuff repair, particularly regarding the supraspinatus tendon. It also illustrates that partial thickness rotator cuff tears on the bursal side exhibit poor mechanical properties that, without proper management, may lead to higher rates of progression. Physicians should consider these findings when developing treatment plans, as they suggest that bursal side injuries may require more aggressive intervention strategies compared to articular side injuries. Future research should focus on validating these findings through clinical trials and examining optimal rehabilitation protocols tailored to different tear types.

کلیدواژه ها:

Rotator cuff ، supraspinatus tendon ، biomechanical properties ، finite element analysis ، tears ، failure load ، modulus of elasticity