Glenoid augmentation for subcritical bone loss: a narrative review.

Background and Objective: Anterior shoulder instability can be debilitating for young, active individuals, and increasing magnitudes of glenoid bone loss (GBL) predisposes patients to recurrent instability and increases the likelihood of failure of soft-tissue only repairs. It is widely accepted that GBL >25% should be treated with a glenoid bone grafting procedure. However, consensus is lacking on the optimal management in the setting of subcritical GBL, typically classified as >13.5%. This article reviews the pathoanatomy relevant to anterior shoulder instability and subcritical GBL, while highlighting existing evidence regarding open augmentation procedures in comparison to other treatment options for this subpopulation. Methods: A narrative review of the current literature was conducted focusing on subcritical GBL in anterior glenoid stabilization procedures, including review of forward citation and reference lists of selected articles. Key Content and Findings: Computed tomography (CT) is the modality of choice for obtaining precise measurements of subcritical GBL, defined as <13.5%, using the best-fit circle method. There is debate surrounding the optimal surgical management of subcritical GBL. Arthroscopic Bankart repair (ABR) remains the predominate surgery performed for primary anterior shoulder instability, while glenoid augmentation and open Bankart repair continue to be used sparingly in the United States. Historically, the Latarjet procedure was considered for substantial glenoid defects, but the illumination of subcritical GBL has expanded its indications. Arthroscopic, soft tissue-only repairs with the addition of remplissage, has been shown to have similar 2-year outcomes to the Latarjet in patients with >15% GBL, which has been limited in the study of subcritical GBL. Additionally, utilization of distal tibial allograft and local autograft is becoming increasingly prevalent. However, again, with limited prospective studies in the subcritical GBL population. Conclusions: There is no consensus regarding the optimal treatment approach to recurrent shoulder instability in the setting of subcritical GBL. Conversely, there is a growing agreement that isolated ABR is likely inadequate and subcritical GBL should prompt consideration of a more robust operation. To this end, interest in glenoid bone augmentation continues to grow as a reliable technique for recreating the native architecture and restoring glenohumeral stability are developed.