The Mechanical Environment of the Supraspinatus During Arm Elevation: A Three-Dimensional Finite Element Analysis

Abstract

Rotator cuff pathology is extremely common, and can significantly reduce one’s function in activities of daily living. The mechanisms of rotator cuff pathology are not well understood. This study aims to understand how supraspinatus stress and strain vary across a range of scapular plane elevation. Secondarily, to understand how imposing humeral head translations in the superior and inferior directions (±2 and ±5 mm) affect tendon mechanics. It was found that both stress and strain increased across the range of arm elevation. The posterior portion of the tendon underwent the greatest amount of strain, while the anterior portion near the footprint experienced the greatest levels of stress. With superior humeral head translation, the maximum stress and strain decreased, while inferior translation caused stress and strain increased. Further study is required to validate the finite element model. Alterations to the model may be done in order to address more clinical questions, such as how varying anatomy and subject specific kinematics affect rotator cuff mechanics.