[Treatment possibilities for bony defects in posterior shoulder instability]

In contrast to anterior instability, posterior instability accounts for only a small proportion of shoulder instability cases; however, chronic or recurrent posterior instability is frequently accompanied by bone loss on the glenoid and humeral side, which plays a critical role in persistent instability and failure of isolated soft-tissue repair. Even moderate osseous defects can significantly compromise glenohumeral biomechanics and joint stability.

Posterior glenoid bone loss leads to a reduction of the concavity-compression mechanism and loss of posterior containment, whereas humeral impression defects in the form of a reverse Hill-Sachs lesion may result in engagement at the posterior glenoid rim. Consequently, surgical strategies addressing osseous deficiencies have gained increasing importance, particularly in cases of chronic instability, substantial bone loss, or failed previous stabilization procedures.

Several bone augmentation techniques have been described to restore posterior glenoid stability. Among these, the Eden-Hybinette procedure and the Kouvalchouk procedure represent established surgical options, each based on different biomechanical concepts. While the Eden-Hybinette technique aims to reconstruct the posterior glenoid rim using a free bone graft, the Kouvalchouk procedure provides functional stabilization through combination of a local posterior bone block and adherent soft tissue augmentation. On the humeral side, anatomical reconstruction of engaging reverse Hill-Sachs lesions using an autologous iliac crest bone graft has been shown to restore humeral head sphericity and prevent recurrent engagement.

Despite increasing clinical use, considerable heterogeneity remains regarding indications, surgical techniques, and reported outcomes of osseous reconstruction procedures for posterior shoulder instability. The aim of this article is to review current surgical treatment options for glenoid and humeral bone defects in posterior shoulder instability, with a particular emphasis on technical aspects, advantages, and limitations of posterior bone block procedures, as well as humeral reconstruction of reverse Hill-Sachs lesions. By critically discussing biomechanical principles, surgical techniques, and clinical outcomes, this review seeks to provide a practical framework for decision-making in the management of this complex pathology.