Finite Element Analysis of Remplissage With Bankart Repair for Anterior Glenohumeral Instability: Reducing Anterior Humeral Head Displacement by Implanting Anchors in the Upper Region of Hill-Sachs Lesions.

Abstract

<h4>Background</h4>The optimal position and number of anchors that need to be implanted in Hill-Sachs lesions (HSLs) during remplissage with Bankart repair (RMBR) to correct anterior glenohumeral instability remain unclear. Previous studies have mainly focused on anchor placement in the central, medial, and peripheral regions, as well as the superior and inferior poles of the HSL, but anchor placement in the upper or lower regions of the HSL has not been investigated.<h4>Purpose</h4>To assess, using finite element analysis, the effect of placing 2 anchors in the superior or inferior regions of the HSL during RMBR on humeral head displacement and postoperative joint stability.<h4>Study design</h4>Controlled laboratory study.<h4>Methods</h4>Finite element models of the glenohumeral joint in the abduction external rotation position were created, including normal models and models with 2 anchors placed in the superior, inferior, or central regions of the HSL. Models with Bankart lesions and HSLs were established based on the normal glenohumeral joint model. Humeral head displacement was calculated by applying anterior dislocation forces and muscle contractions from the infraspinatus and teres minor muscles.<h4>Results</h4>Models with 2 anchors placed in the superior (1.92 ± 0.00 mm) region of the HSL showed less anterior humeral head displacement than those with anchors in the lower (1.95 ± 0.00 mm) or central (1.95 ± 0.00 mm) regions under anterior dislocation load. However, posterior displacement was greater (2.05 ± 0.00 mm vs 1.90 ± 0.00 mm and 1.87 ± 0.00 mm) with anchors placed in the superior region under muscle contraction.<h4>Conclusion</h4>The placement of 2 anchors in the upper portion of the HSL more effectively (<i>P</i> < .001) reduced anterior humeral head displacement than did the placement of anchors in the lower or central regions of the HSL. In clinical practice, external forces on the shoulder joint comparable with those causing dislocation may amplify this displacement difference, rendering it more prominent and clinically relevant. This provides a more refined reference for determining the position and number of anchors that need to be implanted into the HSL during RMBR surgery.<h4>Clinical relevance</h4>The placement of 2 anchors in the upper region of the HSL effectively reduces anterior displacement under simulated dislocation loads, while increasing posterior displacement under muscle contraction. This may enhance postoperative glenohumeral stability and reduce the risk of recurrent dislocations, offering valuable insights for clinical practice.