Analysis of Rotator Cuff Muscle Injury on the Drawing Side of the Recurve Bow: A Finite Element Method

BACKGROUND: This study establishes the shoulder model on the drawing side of recurve archers by the finite element method and finds out the stress changes on the rotator cuff muscles in the position of the humerus and scapula under different stages of special techniques. The aim of this study is to investigate the mechanism of rotator cuff damage on a recurve archer's drawing arm. METHODS: A 22-year-old healthy male's shoulder CT and MRI data were collected, and the drawing side shoulder joint finite element model was constructed, which contains the structure of the shoulder blades, clavicle, humerus, supraspinatus, infraspinatus, teres minor, and subscapularis. The humerus on the drawing arm was simulated to raising the bow, drawing, holding, and releasing on the scapula plane, and stress changes in rotator cuff muscles are analyzed. RESULTS: The peak stress on the infraspinatus increased slowly, and from the start of raising the bow to hold and release, the stress peak increased from 0.007 MPa to 0.009 MPa. The peak stress on teres minor rises slowly from 0.003 MPa at the start of raising the bow to 0.010 MPa at the moment of releasing. The peak stress in the subscapularis increased from 0.096 MPa to 0.163 MPa between the start of raising the bow and releasing. The peak stress on the supraspinatus varied greatly, and from the start of raising the bow to the start of drawing, the stress peak increased markedly from 1.159 MPa to 1.395 MPa. Subsequently, the stress peak immediately decreased to 1.257 MPa at the start of holding and then increased to 1.532 MPa at releasing. CONCLUSION: The position of the humerus and scapula would change with the different stages of special techniques. It causes stress changes in the rotator cuff muscles, and when the stress accumulates over time, the shoulder 5on the drawing side will gradually become injured and dysfunctional. In combination with the depth of the structural site and the surrounding structural features, corrective exercises can be used to prevent injury to the rotator cuff muscles.