Effect of localized tendon remodeling on supraspinatus tear propagation.
Rotator cuff tear propagation is multifactorial and may be due to localized changes in mechanical properties from tendon remodeling based on the inhomogeneous stresses experienced by a tendon with a tear. The objective of this study was to investigate the effect of localized tendon remodeling on tear propagation for simulated supraspinatus tendon tears. A validated computational model of a supraspinatus tendon using subject-specific geometry and material properties with a 1 cm wide anterior tear was used. The medial edge of the supraspinatus tendon was displaced 5 mm to induce tear propagation and cohesive elements were used to model tear propagation. Four remodeling scenarios were investigated: (1) Baseline (no remodeling), (2) Positive remodeling (increased fiber stiffness) and (3) Negative remodeling (decreased fiber stiffness) at tear tips, and (4) Negative remodeling along the medial-lateral tear edge. Output parameters included the amount of tear propagation, critical load to propagate the tear, and maximum principal stress at the tear tips. Positive remodeling at the tear tips resulted in the largest amount of tear propagation (18.4 mm), highest peak maximum principal stress (25.2 MPa), and lowest critical load to propagate the tear (249N). Conversely, negative remodeling at the tear tips resulted in the least amount of tear propagation (16 mm), lowest peak maximum principal stress (17.6 MPa) and highest critical load to propagate the tear (278N). Overall, remodeling at the tear tips has the greatest effect on tear propagation. Therefore, a better method for clinicians to measure tendon stiffness at the tear tips would be helpful to improve outcome of patients.