Anterior shoulder dislocations occur when the humeral head translates anterior to the glenoid cause pain, stiffness, and glenoid bone loss. If left untreated, the risk of recurrence can be up to or greater than 90%. The only surgically modifiable factor to reduce the risk of recurrence is the glenoid bone loss (GBL), where surgeons have the ability to recreate the shape of the glenoid and reduce the risk of recurrent shoulder dislocations.

Established boney procedures for shoulder instability include the Latarjet and free bone block procedures, such as the Anatomic Glenoid Reconstruction (AGR). The Latarjet is well known for its lower rate of recurrent instability, but raises concerns due to under-appreciated complications rates. The AGR is a newer surgical approach that has garnered attention for its low rate of recurrent instability and complication profile. Both treatments can reduce pain, increase function following surgery and reduce the risk of recurrent instability. However, these two established approaches have yet to be directly compared and studied on a larger scale.

The purpose of this randomized control trial is to compare clinical and radiographic outcomes pre- and post-operatively between the Latarjet to the AGR.

Anterior shoulder dislocations are painful and highly prevalent. If left untreated, rates of recurrence can be up to and greater than 90%. The risk of recurrence room is increased with younger age (< 40), male sex, hyperlaxity, participation in contact sports, and GBL. From these factors, GBL is the only modifiable factor and surgical intervention is required. Managing the bone deficiency for instances of shoulder instability has proven to be a surgical challenge.

Established boney procedures for shoulder instability include the open and arthroscopic Latarjet and open and arthroscopic free bone block interventions. Latarjet is considered the gold standard for treating anterior shoulder instability with bone loss, where the coracoid process is cut and transferred with the conjoin tendon through the subscapularis. The coracoid process is then fixed to the anterior glenoid increasing glenohumeral surface area and stability by the addition of the sling effect. Latarjet has proven to result in low recurrent instability but raises concerns due to underappreciated complication rates (15-30%). The arthroscopic glenoid reconstruction (AGR) with distal tibia allograft is an arthroscopic bone block procedure that has recently garnered attention for its low rate of recurrent instability and complications, high levels of patient satisfaction and avoidance of splitting the subscapularis tendon. AGR with a distal tibia uses a new far medial portal, (i.e., Halifax portal) to avoid damaging the neurovascular or musculature while allowing for anatomic repair of the glenoid.

This randomized control trial will compare the gold standard Latarjet to the AGR. This study aims to randomize 68 individuals who experience anterior shoulder instability with GBL. Through a series of clinical and radiographic outcome measures, the study investigators hypothesize the AGR group will demonstrate smaller complication rates, but remain a similar post-operative recurrence rate, and patient reported outcomes. This trial will be the first multi-centre control trial evaluating the Latarjet to the AGR for patients with critical bone loss (>20%). This research has the potential to demonstrate clinical efficacy of a procedure that is safer, more anatomic, with less damage to the subscapular muscle, and an easier revision surgery.

Inclusion Criteria:

• Patients with one or more instances of anterior shoulder dislocation; pre-operative CT scan illustrating >20% bone loss.

Exclusion Criteria:

• posterior shoulder instability; multidirectional shoulder instability; massive rotator cuff teats (MRI proven); history of substance abuse, patients unable to provide informed consent, patients refusing randomization.

The participant will be unaware of the procedure they were randomized to until the 1-year time point.