Biomechanical Effectiveness of an Arthroscopic Posterior Bankart Repair Versus an Open Bone Block Procedure for Posterior Shoulder Instability

Abstract

Background: The most effective surgical treatment for traumatic posterior shoulder instability remains unclear.Hypothesis: An arthroscopic posterior Bankart repair is as effective as an open posterior bone block–capsulorrhaphy procedure regarding the restoration of humeral displacement with posterior and inferior forces.Study Design: Controlled laboratory study.Methods: Biomechanical testing of 16 human shoulders was performed in 3 testing conditions: after ventilation (intact joint), after creation of a posteroinferior Bankart lesion with an additional cut of the posterior band of the inferior glenohumeral ligament, and after surgical shoulder stabilization. The shoulder stabilization was performed either by an open posterior bone block procedure and glenoid-based T-capsulorrhaphy or by an arthroscopic Bankart repair. Testing was performed in 2 positions—the sulcus test position and the jerk test position—with a passive humerus load of 50 N applied in the posterior, posteroinferior, and inferior directions.Results: After the arthroscopic repair, there was no significant difference between the translation and the intact state for all tested directions. The bone block repair–capsulorrhaphy caused a significant decrease of posterior translation (sulcus test and jerk test positions) and posteroinferior translation (jerk test position). But the resulting posterior and posteroinferior translation was even significantly lower than the translation measured for the intact joints. However, the reduction of inferior translation, compared with that of the defect condition, was not significant after the bone block repair (sulcus test and jerk test positions). Compared with that of the intact joint, inferior translation after the bone block repair was significantly higher.Conclusion: The posterior bone block repair–capsulorrhaphy overcorrects posterior translation and does not effectively restore inferior stability, whereas the arthroscopic posterior Bankart repair restores posterior and inferior laxity of the intact joint.Clinical Relevance: An arthroscopic posterior capsulolabral repair more precisely restores posterior and inferior glenohumeral joint laxity and is therefore recommended as the first choice of treatment.