Review Question - QID 220051

This patient presents with recurrent anterior shoulder instability and an off-track, bipolar lesion with critical glenoid bone loss (25%). Of the answers provided, the most appropriate treatment includes a coracoid autograft transfer (i.e., Latarjet procedure) to address the critical glenoid bone loss and provide long-term stability (Answer 4).

Shoulder dislocations often result in long-term anterior shoulder instability. Contributing factors include the patient's type of sport/occupation, age at first dislocation, hyperlaxity, and glenoid bone loss. First-time dislocations in the younger, athletic population result in injury to the anterior-inferior glenohumeral ligament (i.e., Bankart injury), where a trial of nonoperative treatment can be considered versus primary labral repair. Repeated dislocations may result in added anterior-inferior bone loss, which must be considered during operative planning. In general, critical bone loss (~25% of the glenoid width, as demonstrated in this patient) mandates some form of bony augmentation of the anterior-inferior glenoid to prevent recurrent instability. This can be performed via autograft coracoid transfer (Latarjet procedure, Answer 4) or allograft augmentation (i.e., distal tibial allograft).

If there is a concomitant bony injury to the posterior humerus (i.e., Hill-Sachs lesions), it is considered a “bipolar” lesion. Contemporary evaluation and treatment of shoulder instability utilize the concepts of “on-track” and “off-track” lesions (Illustration 1) to help determine the most appropriate treatment options. In cases of subcritical bone loss (~13-25%), bankart repair with concomitant Remplissage can serve as a powerful all-arthroscopic, soft-tissue-only treatment that negates the need for glenoid bone augmentation. However, glenoid bone augmentation is still considered the standard of care for critical bone loss.

Shin and colleagues performed a case-control study investigating the degree of anterior glenoid bone loss that results in recurrent glenohumeral instability after arthroscopic repair. The authors utilized receiver operating characteristics (ROC) in a cohort of 169 patients. They found that at >17.3% bone loss, there was a significantly increased risk for poor outcomes and surgical failure (43.9% recurrence) compared to patients with <17.3% bone loss (3.7% recurrence). The authors concluded that anterior glenoid bone loss of 17.3% or more should be considered a critical amount of bone loss, warranting bone augmentation procedures over arthroscopic labral repair alone.

Itoi provided a comprehensive review regarding “on-track” and “off-track” shoulder lesions. They highlight the concept of the glenoid track, which is the area of the posterior humeral articular surface in contact with the glenoid when the arm moves along the posterior end-range of motion. The authors note that if the Hill-Sachs lesion stays within the glenoid track, no engagement/dislocation should occur. They conclude with an algorithmic treatment approach considering the on-track/off-track concept and degree of the glenoid and Hill-Sachs bone loss.

Privitera and colleagues retrospectively reviewed their institutional outcomes when performing the Latarjet procedure in contact or collision athletes. The authors included 73 shoulders evaluated at a mean follow-up of 52 months and found that approximately half of the patients returned to their pre-operative sports level. Further, patients with multiple prior stabilization procedures before the Latarjet procedure demonstrated a lower likelihood of returning to their original sport. They concluded that the outcomes of the Latarjet procedure in high-risk contact or collision athletes are variable.

Figure A demonstrates the “en-face” view of this patient’s CT 3D reconstruction with 25% glenoid bone loss (60mm / 80mm). Figure B demonstrates their concomitant Hill-Sachs lesion, which extends 17mm from the footprint of the rotator cuff. Illustration 1 demonstrates how to calculate the glenoid track and Hill-Sachs interval to determine if the injury is “on track” (lower risk for recurrent dislocations) or “off track” (higher risk for recurrent dislocations).

Incorrect answers:
Answer 1: All bankart repair procedures should utilize a minimum of 3 anchors for labral repair (<3 anchors incur a risk of inadequate repair and failure with recurrent dislocations). However, due to this patient’s significant glenoid bone loss, performing revision arthroscopic bankart repair alone would portend a high risk for failure and continued instability.
Answer 2: While open bankart repair used to be considered superior to arthroscopic (particularly in revision cases), advances in arthroscopic techniques and implants have resulted in an equivalent risk for recurrent instability. In either case, neither procedure would address this patient’s critical glenoid bone loss.
Answer 3: The Remplissage procedure addresses the Hill Sachs defect by “filling in” the void with soft tissue imbrication (i.e., posterior capsule and infraspinatus). While Remplissage alone would functionally convert his bipolar, off-track lesion to an on-track lesion, it would not address his critical anterior-inferior glenoid bone loss when performed in isolation.
Answer 5: Given his young age, shoulder arthroplasty should only be reserved as a salvage reconstruction option if the patient fails glenoid bone augmentation procedures.