THE ASPETAR APPROACH TO SURGICAL DECISION MAKING IN THE ANTERIOR SHOULDER INSTABILITY

– Written by Gazi Huri, Khalid Al-Khelaifi, Qatar, Ulas Can Kolac, and Mehmet Kaymakoglu, Türkiye

INTRODUCTION

Shoulder instability is a significant clinical issue in sports medicine, particularly among elite athletes who require optimal shoulder function for peak performance. Anterior glenohumeral (GH) instability is the most common form, often resulting from acute trauma or repetitive microinstability in overhead and contact athletes. Epidemiological studies report an incidence of primary anterior shoulder dislocation ranging from 8 to 24 per 100,000 person-years in the general population, with substantially higher rates in contact sports such as rugby, American football, and handball.

In competitive athletes, shoulder instability not only affects performance but also threatens career longevity, demanding urgent and precise clinical decision-making. Athletes, teams, and national sports organizations have high expectations for timely return to play, long-term joint health, and minimal risk of recurrence. These demands require a comprehensive, evidence-based, and interdisciplinary approach to diagnosis and treatment.

This article outlines a practical roadmap for managing GH instability in athletes, integrating biomechanical principles, clinical evaluation, and surgical decision-making. Drawing from both institutional strategies and current literature, we present an algorithmic approach to shoulder stabilization, with emphasis on bipolar lesion management and athlete-specific return-to-play considerations.

BIOMECHANICS AND PATHOANATOMY

The glenohumeral (GH) joint is the most mobile joint in the human body, allowing a wide range of motion required for many athletic activities. However, this mobility comes at the cost of inherent instability, primarily due to its anatomical configuration: a large, spherical humeral head articulates with a relatively shallow and small glenoid fossa, providing limited bony constraint. In the neutral position, only about 60% of the humeral head is in contact with the glenoid. This contact ratio decreases further in abducted and externally rotated positions—common in overhead sports—leading to increased vulnerability to dislocation or subluxation events.

Joint stability is maintained by a complex coordination of static stabilizers (including the labrum, joint capsule, GH ligaments, and glenoid bone morphology) and dynamic stabilizers (primarily the rotator cuff, long head of the biceps, and periscapular muscles). The capsulolabral complex deepens the glenoid socket and acts as a stabilizer to resist translation. The rotator cuff compresses the humeral head into the glenoid, while the scapular stabilizers maintain appropriate glenoid orientation during dynamic movements.

The classic mechanism for anterior dislocation is a forceful abduction combined with external rotation. This motion stresses the anteroinferior capsulolabral complex and may result in a Bankart lesion—an avulsion of the labrum from the glenoid rim. During the reduction phase, the posterolateral aspect of the humeral head may impact against the anterior glenoid rim, leading to a compression fracture known as a Hill-Sachs lesion. These two injuries—a Bankart lesion and a Hill-Sachs lesion—often occur together, forming what is known as a bipolar lesion, observed in over 80% of cases of traumatic anterior instability.

Recurrent instability affects shoulder kinematics and may lead to cumulative damage. Repeated subluxation or dislocation events can progressively erode the glenoid bone, increasing the likelihood of engagement and recurrence. Additionally, in high-demand athletes, even microinstability without frank dislocation can disrupt performance by causing pain, apprehension, or fatigue-induced functional instability.

Understanding these biomechanical principles is crucial not only for diagnosis but also for surgical planning. Management strategies must account for the size and interaction of the bony defects, the quality of the soft tissues, and the specific demands of the athlete’s sport. Without this foundation, treatment may fail to restore stability or allow safe return to play.

EVALUATION AND CLASSIFICATION

A comprehensive evaluation of shoulder instability must go beyond the initial physical examination. It requires a holistic approach that integrates patient history, sport-specific demands, clinical testing, and advanced imaging modalities. The goal is not only to identify structural damage but also to understand functional instability and tailor interventions accordingly—especially in elite athletes whose careers depend on precise shoulder performance.

History taking plays a pivotal role. Key elements include the mechanism of injury (traumatic vs. atraumatic), number of instability episodes, associated symptoms such as pain or weakness, and prior treatments. The athlete’s specific sport, playing position, and level of competition are essential in assessing functional demands and expectations from treatment. For instance, an overhead thrower with a single dislocation may require a different strategy than a contact athlete with multiple episodes.

Clinical examination assesses both static and dynamic stability. Provocative tests such as the apprehension, relocation, and anterior drawer tests evaluate capsulolabral integrity. Beighton score or generalized hypermobility may indicate underlying laxity. Strength testing of the rotator cuff and periscapular musculature helps identify dynamic insufficiency, which often coexists with structural lesions in athletes with subtle or recurrent instability.

Sport-specific functional assessment is equally critical. Observing movement patterns—such as throwing mechanics or tackling technique—may reveal scapular dyskinesis, altered kinetic chains, or compensatory strategies that perpetuate instability or pain. Video analysis or wearable motion sensors can further enhance evaluation in professional environments.

Advanced imaging is indispensable for preoperative planning. Magnetic resonance imaging (MRI), ideally with arthrogram (MRA), provides detailed visualization of the labrum, capsule, glenohumeral ligaments, and associated soft tissue pathology. For bone loss assessment, computed tomography (CT) with 3D reconstructions offers superior accuracy, particularly in quantifying glenoid defects and humeral head engagement.

One of the most impactful tools in modern shoulder instability classification is the on-track/off-track concept, derived from the glenoid track theory. This biomechanical model evaluates whether a Hill-Sachs lesion remains within the glenoid arc during movement (on-track) or engages the glenoid rim (off-track), significantly influencing surgical decision-making. Off-track lesions are strongly associated with failure of isolated soft-tissue repairs, necessitating additional bony or remplissage procedures.

We routinely apply the Baker classification to assess the pathoanatomy in first-time dislocators. This system stratifies injury severity and tissue quality, helping anticipate recurrence risk and guide operative versus non-operative strategies. Notably, even a single dislocation in an athlete can result in irreversible labral detachment and capsuloligamentous stretching, which compromises long-term shoulder stability.

Additional prognostic factors include patient age, with younger athletes (<25 years) exhibiting higher recurrence; joint laxity, which predisposes to both traumatic and atraumatic instability; and limb dominance, especially relevant in throwing sports. Associated injuries such as SLAP tears, rotator cuff pathology, or bony Bankart lesions further complicate the clinical picture and require tailored management.

Ultimately, classifying instability is not about assigning a static label but about dynamically integrating clinical, radiographic, and biomechanical information. This allows the treating team to stratify risk, select optimal interventions, and design personalized rehabilitation pathways that facilitate a durable and safe return to sport.

SURGICAL ALGORITHM FOR ANTERIOR GLENOHUMERAL INSTABILITY

Our treatment strategy is rooted in biomechanical logic and clinical outcomes. The key factors guiding intervention include glenoid bone loss, Hill-Sachs status, labral condition, and the athlete’s functional demands.

In cases where there is an on-track Hill-Sachs lesion with less than 10% glenoid bone loss and a repairable labrum, isolated Bankart repair is the preferred approach. This scenario is most common in younger athletes with minimal bony pathology, Figure 1.

When the labrum is degenerated or non-viable, despite the lesion being on-track, middle glenohumeral ligament (MGHL) augmentation can be used to reinforce anterior stability, providing added resistance to anterior translation, Figure 2.

For athletes presenting with off-track Hill-Sachs lesions and less than 10% glenoid bone loss, the addition of remplissage to Bankart repair is our recommended strategy. This helps prevent engagement of the Hill-Sachs lesion during functional movements, Figure 3.

In cases involving combined anterior and superior labral pathology, such as a SLAP Type II lesion accompanying a Bankart lesion, both lesions are repaired arthroscopically to restore stability, Figure 4.

Athletes with moderate glenoid bone loss (10–15%) and high functional demands, especially those engaged in overhead or collision sports, are treated with dynamic anterior stabilization (DAS). This involves transferring the long head of the biceps through a subscapularis split in combination with Bankart repair, and often with remplissage. The result is a soft-tissue sling effect that dynamically reinforces anterior restraint, Figure 5.

The Latarjet procedure is reserved for cases with more than 15% glenoid bone loss or for contact athletes who are considered at high risk of recurrence. The conjoined tendon acts as a dynamic sling, while the coracoid graft restores anterior glenoid bone stock.

Lastly, even in seemingly stable, on-track lesions, overhead or high-contact athletes may benefit from remplissage to limit subtle translation and lower the risk of recurrence under extreme loads.

SURGICAL PEARLS AND INTRAOPERATIVE ASSESSMENT

Intraoperative translation and dynamic examination are essential. If posterior translation persists after Bankart repair, remplissage is added. Single portal remplissage techniques have reduced invasiveness and improved graft integration. DAS techniques require subscapularis management and anatomical biceps transfer, validated via cadaveric dissection.

REHABILITATION AND RETURN TO SPORT

Postoperative rehabilitation is a critical component of successful treatment for shoulder instability, particularly in athletes whose performance hinges on precise, coordinated upper limb function. Rehabilitation protocols must be individualized—not only to the specific surgical procedure performed but also to the athlete’s sport, position, competition level, and overall biomechanical profile.

In high-performance environments such as Aspetar, individualized plans are developed using a multidisciplinary approach, incorporating biomechanics lab testing, clinical milestones, and sport-specific simulations. This holistic, athlete-centered approach ensures that return to competition is not only safe but also sustainable—reducing the risk of recurrence and optimizing long-term shoulder health.

CONCLUSION

GH instability in athletes must be understood as a bipolar, athlete-specific pathology. An algorithmic approach that integrates imaging, biomechanics, and individual risk profiles can help guide treatment decisions and optimize outcomes. By combining evidence-based techniques with individualized care, clinicians can achieve safe, timely, and sustainable return to sport. Dynamic stabilization, accurate preoperative classification, and strategic intraoperative decision-making are essential components of successful shoulder instability management.

Gazi Huri MD

Orthopaedic Surgeon

Coordinator of Sport Orthopedics Fellowship Programme

Aspetar Orthopaedic and Sports Medicine Hospital

Doha, Qatar

Khalid Al-Khelaifi MD

Orthopaedic Surgeon

Director of the Visiting Surgeon Program

Aspetar Orthopaedic and Sports Medicine Hospital

Doha, Qatar

Mehmet Kaymakoglu MD

Orthopaedic Surgeon

Department of Orthopaedics and Traumatology

Izmir University of Economics

Izmir, Türkiye

Ulas Can Kolac MD

Orthopaedic Surgery Resident

Department of Orthopaedics and Traumatology

Hacettepe University Faculty of Medicine

Ankara, Türkiye

Contact: gazi.huri@aspetar.com

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