Editorial Commentary: Recurrent Anterior Shoulder Instability With Glenoid Bone Loss Requires Restoring the Bone

The success of treating anterior glenohumeral instability relies on multiple factors, including glenoid bone loss. Subcritical bone loss (<13.5%) has proven again and again to be a critical consideration when treating this problem. This proves more challenging in a population that participates in contact sports. The importance of restoring native anatomy, including the glenoid bone, is critical in ensuring a successful outcome. This is especially true in the setting of a bony Bankart lesion, where merely repairing the soft tissues and ignoring the bony fragment leads to unfavorable results.     

Editorial Commentary: Dynamic Anterior Stabilization via Biceps Tenodesis to the Glenoid Is an Option for Anterior Shoulder Instability With Subcritical Glenoid Bone Loss

A nuanced approach to treatment of anterior shoulder instability is encouraged, particularly in patients with subcritical glenoid bone loss. In patients with bone loss, recurrent instability after isolated arthroscopic Bankart repair has dampened enthusiasm for this procedure. Adjunctive treatment with remplissage or dynamic anterior stabilization via biceps tenodesis to the glenoid is an alternative to bone transfer procedures, which are effective but have higher complication rates. Dynamic anterior stabilization or tenodesis of the long head of the biceps to the 3-o’clock position on the glenoid through a subscapularis split is biomechanically superior to isolated Bankart repair for reducing anterior translation, even in the setting of minor glenoid bone loss due to a sling effect similar to that produced by the Latarjet procedure. A disadvantage is placement of a large implant into the small space of the anterior glenoid and creation of a soft-tissue defect in the capsule.     

Glenoid Bone Loss in Shoulder Instability: Superiority of Three-Dimensional Computed Tomography over Two-Dimensional Magnetic Resonance Imaging Using Established Methodology

BackgroudRecent literature suggests that three-dimensional magnetic resonance imaging (3D MRI) can replace 3D computed tomography (3D CT) when evaluating glenoid bone loss in patients with shoulder instability. We aimed to examine if 2D MRI in conjunction with a validated predictive formula for assessment of glenoid height is equivalent to the gold standard 3D CT scans for patients with recurrent glenohumeral instability.MethodsPatients with recurrent shoulder instability and available imaging were retrospectively reviewed. Glenoid height on 3D CT and 2D MRI was measured by two blinded raters. Difference and equivalence testing were performed using a paired t-test and two one-sided tests, respectively. The interclass correlation coefficient (ICC) was used to test for interrater reliability, and percent agreement between the measurements of one reviewer was used to assess intrarater reliability.ResultsUsing an equivalence margin of 1 mm, 3D CT and 2D MRI were found to be different (p = 0.123). The mean glenoid height was significantly different when measured on 2D MRI (39.09 ± 2.93 mm) compared to 3D CT (38.71 ± 2.89 mm) (p = 0.032). The mean glenoid width was significantly different between 3D CT (30.13 ± 2.43 mm) and 2D MRI (27.45 ± 1.72 mm) (p < 0.001). The 3D CT measurements had better interrater agreement (ICC, 0.91) than 2D MRI measurements (ICC, 0.8). intrarater agreement was also higher on CT.ConclusionsMeasurements of glenoid height using 3D CT and 2D MRI with subsequent calculation of the glenoid width using a validated methodology were not equivalent, and 3D CT was superior. Based on the validated methods for the measurement of glenoid bone loss on advanced imaging studies, 3D CT study must be preferred over 2D MRI in order to estimate the amount of glenoid bone loss in candidates for shoulder stabilization surgery and to assist in surgical decision-making.     

Editorial Commentary: Free Bone Block With Remplissage Provides Less Translation Than Free Bone Block Alone in Shoulder Instability Patients With Bipolar Bone Loss

It would stand to reason that, in shoulder instability patients with bipolar bone loss, the combination of a bone block procedure and a remplissage procedure would provide better results than each one alone. Why would this be the case? When performing these procedures in the lateral decubitus position for patients with critical bipolar bone loss, the humeral head is anteriorly and inferiorly subluxed. This is most likely due to the incompetent restraints when in traction. A bone block procedure alone doesn’t necessarily reduce the glenohumeral center of rotation; rather, it increases the “jump distance,” making it more difficult for the humerus to dislocate over the bone block. However, the remplissage procedure not only makes the Hill-Sachs lesion extra-articular and prevents the defect from levering out the humerus, but also seems to pull the humeral head posteriorly centering it in the glenoid. This provides a posterior tether to the humeral head while increasing the jump distance over the bone block even further. In the future, one can anticipate a significant increase in remplissage-augmented bone block procedures in patients with bipolar bone loss.     

Editorial Commentary: Bone Loss in Shoulder Instability Occurs in 3 Dimensions

The continued debate regarding the appropriate threshold to consider performing bony stabilization procedures in the treatment of shoulder instability has contributed to a recent boom of new research in this area. The contribution of both glenoid bone loss and version in predicting potential clinical failure after soft tissue stabilization is one of those topics. The authors of the featured study demonstrate the relationship between measured glenoid version and bone loss, which can assist us in our clinical decision making. To date, most measures of glenoid version have been reported based on analysis of 2 dimensions. However, with 2-dimensional analysis, bone loss may result in potentially errant measurement of version and require subsequent correction. Moreover, 3-dimensional analysis could result in a more nuanced understanding of the complexities of glenoid pathologic study in patients with shoulder instability.     

Editorial Commentary: Shoulder Remplissage Is a Beneficial Addition to Bankart or Glenoid Bone Loss Treatment: Stay on Track and Use Wisely

In patients with on-track shoulder Hill–Sachs lesions, the addition of remplissage using a double-pulley technique to Bankart repair improves outcomes including residual apprehension and without loss of external rotation. A caveat is that measurement of both the Hill–Sachs lesion and glenoid bone loss may be inconsistent. A second caveat is that determination of the glenoid track can be affected by scapular positioning. Not all “on-track” lesions are alike. In terms of outcome assessment, apprehension has up to 95% specificity for anterior shoulder instability and is a key finding in determining the results of shoulder stabilization. Recurrent instability may not be as sensitive of an outcome measure, because patients will avoid positions of apprehension. Finally, remplissage should be used cautiously in peripheral track lesions. For smaller Hill–Sachs lesions, remplissage can provide extraordinary success, and for larger lesions that are close to engaging, glenoid bone loss must also be treated, especially in a younger, active patient.     

Proper Evaluation of Bone Loss Determines Shoulder Instability Indications and Outcomes

One of the most-read articles published in the history of Arthroscopy: The Journal of Arthroscopic and Related Surgery is “Evolving Concept of Bipolar Bone Loss and the Hill-Sachs Lesion: From ‘Engaging/Non-Engaging’ Lesion to ‘On-Track/Off-Track’ Lesion” by Di Giacomo, Itoi, and Burkhart. This 2014 article is a modern classic and has inspired a plethora of recent research as well as infographics published in Arthroscopy. We now understand, to the great benefit of patients, that proper evaluation of bone loss determines shoulder instability surgical indications and outcomes.