Managing bone loss in shoulder instability

When I am seeing a patient with a history of shoulder instability, the first question I ask myself is: “How much bone loss are we dealing with?” This is especially true for patients who sustained a high energy injury or have had recurrent episodes of instability. The amount of glenoid (bony Bankart) and/or humeral head (Hill-Sachs defect) bone loss in the setting of shoulder instability is a well-known risk factor for failure of an arthroscopic repair and, therefore, is important to consider when choosing the appropriate treatment.

Bone loss in the shoulder is typically reported as a percentage of the expected native bone. In my experience, the most accurate method to assess the amount of bone loss is with a 3D computed tomography (CT) scan using humeral head subtraction. Glenoid bone loss is commonly referred to as either minimal (<10%), moderate (10−25%), or severe (>25%). Hill-Sachs lesions are also best measured on CT scan and are typically classified as small (<20%), medium (20–40%), or large (>40%). The concept of a glenoid track is an important classification for Hill-Sachs lesions because it accounts for both glenoid and humeral bone loss. Lesions are termed “on-track” or “off-track.” Off-track lesions are those that will engage the anterior rim of the glenoid with normal shoulder range of motion and thus require additional attention.

Picking the correct surgery for your patient with shoulder instability and bone loss can be challenging and these options are a topic of frequent debate among shoulder surgeons. In general, when there is significant bone loss, those patients are going to be best treated with a procedure that restores the bony architecture of the joint. It is the patient with minimal to moderate bone loss who can pose a more challenging treatment dilemma.

In my practice, patients with a history of anterior shoulder instability without prior surgery, <15% glenoid bone loss, and an on-track Hill-Sachs lesion will be treated with an arthroscopic Bankart repair. When there is an off-track Hill-Sachs lesion and <15% glenoid bone loss, I recommend the addition of a remplissage. For >15% glenoid bone loss or in the setting of a failed repair, then I would recommend bony augmentation with a Latarjet. The Laterjet procedure does not adequately augment patients with >30% bone loss and therefore in this challenging patient, I recommend iliac crest autograft or fresh osteoarticular distal tibial allograft reconstruction. I would like to note that one should avoid the pitfall of making treatment recommendations based solely on radiographic imaging. Each patient should be considered individually, and the best-fit treatment plan should also take into consideration the patient’s age, activity level, and sport of choice.

When the correct surgery is chosen, the outcomes of an arthroscopic Bankart repair (with or without   remplissage) have been shown to be similar to that of an open Latarjet. A meta-analysis by Haourn et al¹ demonstrated that for patients with <20% glenoid bone loss treated for anterior shoulder instability with either an arthroscopic Bankart repair and remplissage or open Latarjet, the rate of recurrent instability had comparable risk ratios. Additionally, there was no significant difference in postoperative range of motion or Rowe or visual analog scale pain scores. The Latarjet group, however, had significantly more complications. Hurley et al² reported no significant differences in return to play, return to preinjury level, or recurrent dislocation rates in patients treated with an open Latarjet (average glenoid bone loss 11.8% and 45% with off-track Hill-Sachs lesions) versus an arthroscopic Bankart repair (average glenoid bone loss 1.9% and 9.7% with off-track Hill-Sachs lesions). There are obvious differences in the amount of bone loss between these groups, highlighting the importance of picking the correct surgery. In another study by MacDonald et al³, the addition of a remplissage to an arthroscopic Bankart for treatment of an off-track lesion in the setting of minimal glenoid bone loss has been shown to significantly reduce the redislocation rate without significant decrease in range of motion.

In conclusion, when caring for a patient with anterior shoulder instability, always consider the possibility of bone loss either on the glenoid or the humeral head as a possible contributing factor to their instability. Minimal bone loss can be successfully managed with an arthroscopic repair whereas consideration for a bony augmentation should be made in patients with significant bone loss. Similar results can be expected when the correct surgery is chosen but it is important to consider the additional complication risk with associated with the Latarjet procedure.