Biomechanical analysis of a finite element model of rotator cuff

Abstract

Objective To establish a finite element model of rotator cuff which can be used to simulate the rotator cuff injury and to evaluate the biomechanical effects of rotator cuff surgery. Methods The DICOM CT images of the right shoulder of a Chinese healthy volunteer were used to establish models of the scapula, humerus and clavicle. The rotator cuff structures were separated and modeled based on the MRI images and anatomical knowledge. After the rotator cuff model was introduced into the finite element analysis software Abaqus 6.12, the anatomical positions were simulated when the shoulder was at 30° internal rotation, 30° external rotation, 30° abduction, 30° adduction, 30° flexion and 30° extension. Results When the shoulder was in 30° flexion, the average stress was 52.2 kPa on the supraspinatus, 223.0 kPa on the infraspinatus and the teres minor, and 90.4 kPa on the subscapularis. When the shoulder was in 30° extension, the average stress was 105.0 kPa on the supraspinatus, 78.2 kPa on the infraspinatus and the teres minor, and 55.7 kPa on the subscapularis, indicating that the muscle and tendon of the supraspinatus was subjected to greater stress and the humerus and the scapula produced less stress compared with the shoulder in 30° flexion. Conclusion Since our finite element model of the rotator cuff can simulate common activities of the shoulder joint and obtain stress values of the corresponding rotator cuff muscles, it can be used in simulation of rotator cuff injury and its surgery. Key words: Finite element analysis; Shoulder; Biomechanics