Anterior shoulder instability is common in young athletes and is the most ordinary form of shoulder instability. The typical presentation of anterior shoulder instability is the result of a traumatic event leading to complete loss of the glenohumeral relationship as seen in a complete anterior shoulder dislocation. The general mechanism is a result from a direct collision or a fall on an outstretched hand with the arm abducted and externally rotated.^1,2 The incidence of traumatic anterior shoulder dislocation ranges from 11.2 to 23.9 in 100,000 injuries^3,4 and has an overall incidence of approximately 1.7% with a predominance among the male population in their second and third decades participating in contact sports.⁵

Throughout orthopedic literature, there is much debate on the most appropriate course of treatment when discussing the “first time dislocator.” In a survey of the Neer Circle of the American Shoulder and Elbow Surgeons, athletes between the ages of 14 and 30 were evaluated and surgical treatment was recommended at the end of the season when clinical findings of apprehension and bone loss were found. In recent studies, nonsurgical management has been shown to result in increased risk of recurrence and a notable increased risk of bone loss.⁶ The effectiveness of rehabilitation alone is still debated for patients who have sustained a primary traumatic dislocation. A study conducted by Burkhead and Rockwood evaluated 115 patients with traumatic and atraumatic recurrent shoulder instability, who underwent nonsurgical management with a dedicated shoulder strengthening program. They found that 16% of patients who had traumatic etiology had excellent or satisfactory results in comparison to 80% who had an atraumatic etiology.⁷ Primary surgical intervention for first-time dislocation in the collegiate athlete, however, has shown higher rates of return to sport in the upcoming season; however, in high-school-level athletes, there has been some documented success in nonsurgical management when considering return to sport.^8,9 Overall, the consensus for symptomatic athletes wishing to continue to play at an elevated level has been surgical management.

As understanding of anterior shoulder instability has advanced, and surgical technique and instrumentation has improved; arthroscopic results have now approached those seen with purely open procedures. Studies done at this author’s institution showed a 97% satisfactory outcome at short-term follow-up with 93% stable shoulders in a patient population with high physical demands and expectations.¹⁰

Several studies have demonstrated the importance of the capsulolabral structures at the anteroinferior aspect of the shoulder in maintaining a congruent and stable shoulder joint.^{11, 12, 13 and 14} The primary static restraint to anterior glenohumeral translation in the abducted shoulder is the inferior glenohumeral ligament that anchors to the anteroinferior labrum.¹⁵ An avulsion of these primary stabilizing structures from the glenoid rim and the neck has been previously described by Perthes¹⁶ and Bankart¹⁷ as the essential lesion that leads to recurrent anterior shoulder instability. During traumatic anterior shoulder instability, this essential lesion has been shown through biomechanical studies and arthroscopic observation to be present approximately 80% of the time.^11,18

As described previously, open techniques for the repair of the anteroinferior capsulolabral structures have historically been the standard of care for the anterior dislocator with documented recurrence rates of less than 10%.¹⁹ Although Rowe et al reported a 96.5% success rate, only two-thirds
of the study population were reevaluated, and only one-third of those involved in athletics returned to competitive sport.¹⁹ There are also downsides to the open technique, primarily concern with the integrity and power of the subscapularis. This can lead to postoperative complications such as loss of external rotation and deficiency in the dynamic stabilizers of the shoulder.²⁰ When looking at overhead athletes, Bigliani et al reported only a 67% rate of return to the previous level of play following an open capsular shift technique.²¹ Although surgical treatment with an open technique historically has produced excellent results, the standard of treatment has shifted toward arthroscopic treatment.

When conducting the primary evaluation of a patient with a primary anterior shoulder dislocation or chronic instability, it is paramount to perform a thorough history and physical examination. This should include a detailed assessment of additional risk factors for recurrence, as this facilitates decision making when determining the proper course of definitive management. On initial clinical evaluation, it is important to ask about present and past activity level and prior history of trauma, including complete dislocation requiring manual reduction. Patients may describe the classic “clunk” or other mechanical symptoms such as popping or clicking, and some may report the ability to relocate the shoulder independently. Others who may have more subtle instability may present with vague reports of pain or weakness when the arm is placed in certain positions, particularly in an abducted/externally rotated position, which leads to significant discomfort to the anterior shoulder and positive apprehension. A thorough history should also include questions about the patient’s age, sex, hand dominance, activity level, associated injuries, and genetic factors. Young males are known to be at an increased risk for recurrent shoulder instability. In addition, younger age at the time of primary traumatic anterior shoulder dislocation has been correlated with an increased risk for recurrent instability and athletes who participate in contact sports or athletics that involve overhead activity are at a higher risk for redislocation. During the initial evaluation, it is of foremost importance to also consider atraumatic causes of recurrent instability, which may be secondary to generalized ligamentous laxity derived from soft-tissue disorders such as Marfan syndrome and Ehlers-Danlos syndrome to name a few. Patients with generalized ligamentous laxity are at an increased risk for recurrent instability, as well as primary dislocation events, and may require additional surgical management, as opposed to, purely a Bankart procedure.

Performance of an in-depth physical examination is of utmost importance to appropriately evaluate and diagnose anterior shoulder instability. The examination must be goal-directed and conducted in a precise and sequential manner beginning with a thorough inspection of the patient’s topographical anatomy. This must be done with the shirt removed to evaluate for notable scars indicating history of trauma or surgical procedures. Atrophy of the shoulder girdle musculature and shoulder symmetry must also be evaluated carefully, as does scapular positioning and the patient’s resting posture. Once inspection is complete, the practitioner must perform an evaluation of the patient’s arc of motion in all planes, including forward flexion, abduction, internal rotation, and external rotation. This should be done actively and passively to assess for generalized shoulder weakness, physical blocks to motion, and imbalance in the soft tissues surrounding the glenohumeral joint. It is important to note the degree of soft-tissue mobility, as this may indicate underlying genetic factors that could significantly contribute to shoulder instability. All bony landmarks must be palpated, including the clavicle, the coracoid, the acromion, the acromioclavicular joint, as well as the insertion of the supraspinatus and infraspinatus. A thorough neurological evaluation must be obtained,
comparing the symmetry of muscular engagement and evaluation of each component of the rotator cuff, as massive subscapularis tears may manifest as clinical anterior shoulder instability.