Abstract:
"A Theoretical Model of the Effect of Bone Defects on Anterior Shoulder Instability: A finite Element Approach"
Anterior shoulder instability, often leading to subluxation and recurrent dislocation, is a prevalent orthopedic issue. The presence of glenohumeral bone defects, such as a Hill-Sachs lesion on the humeral head or a bony Bankart lesion on the glenoid, has been identified as a significant contributing factor to this instability. While previous biomechanical studies have typically investigated the effects of isolated humeral or glenoid defects, the reality of clinical scenarios often involves combined defects, which may exacerbate instability through complex biomechanical interactions. This study addresses this critical gap by employing a sophisticated computer-based finite element (FE) approach to investigate the intricate effects of both isolated and combined glenoid and humeral defects on the stability of the glenohumeral joint.
A generic biomechanical model of the glenohumeral joint, encompassing both cartilage and bone components of the glenoid and humerus, was meticulously developed based on comprehensive previously published anatomical and mechanical data. Static analysis with displacement control was utilized, specifically applying anterior-inferior displacement to simulate instability events, alongside a 50-N compressive load to replicate physiological joint loading. The model systematically simulated various defect configurations, including different sizes and locations of Hill-Sachs and bony Bankart lesions, both in isolation and in combination. This allowed for a detailed biomechanical assessment of their individual and synergistic impacts on joint kinematics, contact mechanics, and overall stability.
The results of this biomechanical investigation demonstrate that the presence of combined bone defects significantly compromises glenohumeral joint stability to a greater extent than isolated defects, leading to increased joint translation and reduced load-bearing capacity. The model provided quantitative predictions of how defect size and location influence the risk of subluxation and dislocation. This theoretical biomechanical framework offers invaluable insights into the complex interplay between humeral and glenoid bone loss, providing a robust tool for understanding the biomechanical mechanisms underlying recurrent anterior shoulder instability. The findings have direct clinical implications for guiding surgical decision-making, particularly in cases where combined bone defects are present, aiming to restore optimal shoulder biomechanics and prevent recurrent instability.
