Stress Distribution within the Rotator Cuff Tendon with a Crescent-shaped and an L-shaped Tears

INTRODUCTION: There are various shapes of full-thickness rotator cuff tears, but they are mainly categorized into two types; crescent-shaped and L-shaped tears. Although it is widely accepted that the tear often propagates with time, the exact propagation pattern in each type of tear is still remains unknown. In the present study, we attempted to clarify the stress distribution in the tendons with a full-thickness rotator cuff tear using threedimensional finite element (FE) method. Particularly, we compared the stress distribution pattern between a crescent-shaped and an L-shaped tears to clarify the differences of their propagation patterns. MATERIALS AND METHODS: Geometric data of the specimen A normal cadaveric shoulder (69-year-old male) was used for the current study (Fig. 1-a). All soft tissues except the rotator cuff tendons were removed and the specimen was examined with CT scan to obtain its DICOM-format data. Then, the data were imported to a workstation to develop a three-dimensional model of the rotator cuff tendons attached to the humeral head using software designed for the finite element analysis, Mechanical Finder (version 6.0, extended edition, Research Center of Computational Mechanics Inc., Tokyo, Japan). The specimen was modeled with 1.0-mm tetrahedron solid elements (Fig. 1c).