Labral Augmentation Decreases Humeral Head Displacement and Cartilage Stress in an Anterior Shoulder Instability Model With Subcritical Glenoid Bone Loss: A Finite Element Analysis.

PURPOSE: To investigate the influence of labral augmentation on glenohumeral biomechanics for anterior glenohumeral instability patients via finite element analysis (FEA).

METHODS: A shoulder finite element model was derived from preoperative computed tomography scans of five patients with anterior shoulder instability and subcritical glenoid bone loss (13.5%-25% of inferior glenoid width). Four models were established based on the affected shoulders, including a model of Bankart lesion combined with subcritical glenoid bone loss, a model of isolated Bankart repair, a model of Bankart repair plus remplissage, and a model of labral augmentation. The contralateral, unaffected shoulders served as normal controls. These five models were tested to assess humeral head displacement and stress on the joint capsule and cartilage.

RESULTS: Labral augmentation outperformed Bankart repair with or without remplissage in restoring native joint characteristics. It limited humeral head displacement to control-like levels (8.10 ± 0.58 vs 7.61 ± 0.46 mm, P = .18), normalized capsular stress (2.00 ± 0.20 vs 1.82 ± 0.23 MPa, P = .221), and reduced cartilage stress on the glenoid and humeral head to pre-injury baselines (glenoid: 2.65 ± 0.18 vs 2.75 ± 0.23 MPa, P = .484; humeral head: 29.70 ± 1.92 vs 30.31 ± 1.93 MPa, P = .630).

CONCLUSIONS: In this FEA of anterior shoulder instability with subcritical bone loss, labral augmentation decreased humeral head displacement and restored articular cartilage stress to an intact state compared to Bankart repair with or without remplissage.

CLINICAL RELEVANCE: This FEA study suggests labral augmentation in the context of subcritical bone loss may be a viable surgical treatment option for patients with shoulder instability.