A detailed history and examination are important in the assessment of patients with first-time anterior shoulder dislocation. Assessment should be aimed to establish satisfactory glenohumeral joint reduction, rotator cuff function, neurovascular status, and determination of the presence of a bony Bankart lesion, as these factors can influence early management [27]. A true anteroposterior, scapular Y, and axillary views should be obtained to determine the direction of the dislocation as well as other pathology that may be apparent before any attempt of manipulation and reduction can be made [28]. Post-reduction radiography is also mandatory to confirm a congruent reduction and reassess the position of any associated fractures [29]. If there is any doubt regarding the extent of osseous injury, a 3-dimensional computed tomography (CT) scan should be performed.

A magnetic resonance imaging (MRI) is generally viewed as the gold standard for soft tissue pathology associated with shoulder instability. With MRI, capsular and ligament detachments, labral lesions, rotator cuff tears, and articular cartilage lesions can be identified more accurately than on CT scan or radiography. The addition of intraarticular contrast in an magnetic resonance arthrography identifies labral tears with a sensitivity of 88% to 96% and a specificity of 91% to 98% [30,31].

However, initial MRI is not typically required to confirm a labral tear in traumatic anterior dislocations because it is known to have a prevalence of nearly 90% in such injuries of young patients. Nevertheless, if pain and instability persist after initial closed reduction and immobilization in patients with higher risk of recurrent instability (e.g., young age, male, contact sports, or shoulder hyperlaxity), MRI should be performed to help better counsel patients regarding the benefit of early shoulder stabilization surgery as an option to decrease the risk of recurrence and associated intra-articular glenohumeral lesions [32].

Rotator cuff should be thoroughly examined in elderly patients. It can be difficult to diagnose a rotator cuff tear in the initial phase due to pain. Therefore, rotator cuff integrity should be assessed after the reduction of pain through the reduction of dislocation and immobilization within 2 weeks. Either the Jobe test or empty can test is preferred to assess the supraspinatus pathology. The belly press and modified lift off tests are commonly used to assess subscapularis tears [33]. If pain and muscle weakness after a shoulder dislocation is persisted, MRI with arthrography or CT arthrography should be performed.

Finally, a thorough neurovascular examination should be performed, paying special attention to the axillary nerve. Axillary nerve palsy is usually presented as a loss of shoulder abduction and loss of sensation in the proximal-lateral aspect of the arm. The arm is evaluated for brachial plexus injury, which is usually represented as a sensory and/or motor weakness distally in the arm. Although suggestive, these features are not diagnostic in older patients. It is critical to rule out massive rotator cuff tear before diagnosing nerve palsy. For patients with persistent symptoms after shoulder dislocation and with MRI findings that are negative for rotator cuff tear, it is reasonable to obtain electromyograpy studies to evaluate for nerve palsy [19,20,24]. Vascular injury is assessed by looking for evidence of expanding hematoma, which may indicate arterial/venous injury after recent dislocation. The distal radial and ulnar pulses should be evaluated and compared with those of the contralateral side.

Whether a patient with first-time anterior shoulder dislocation undergoes conservative or surgical treatment, immediate reduction and immobilization are initial recommendations. Reduction should be done carefully to avoid any additional bony or soft tissue injury. Because there is no significant difference in the success of reduction, familiar and skillful reduction techniques can be attempted [34,35]. The initial reduction is usually followed by a period of immobilization, which can be performed for pain control or patient There is also controversy regarding the duration of immobilization following first-time traumatic anterior shoulder dislocation in the literature. A common recommendation is immobilization for 1 to 3 weeks in a sling to allow for early capsular healing, followed by several months of rehabilitation, including range of motion and strengthening exercises.

Kiviluoto et al. [36] performed a study on 226 patients who had first-time traumatic anterior shoulder dislocation with 1-year follow-up. A significant reduction in the rate of recurrence was noted between patients with immobilization for 3 weeks and patients with immobilization for 1 week (23% vs. 50%, p<0.05). They recommended that patients should be immobilized for 3 weeks to a sling for early capsular healing. Simonet and Cofield [37] performed a study on 116 patients who were treated for anterior glenohumeral dislocation for the first time at a mean follow-up of 4.63 years. Recurrence was noted to be significantly more common in younger patients. Patients who were restricted from playing sports for 6 weeks or more had significantly better results than those restricted for less than 6 weeks. Thus, they advised immobilization for 3 to 6 weeks followed by extensive rehabilitation before returning to athletic activity [37,38]. Conversely, Paterson et al. [35] performed a meta-analysis on patients aged <30 years who were managed with immobilization in internal rotation for either <1 week or >3 weeks. There were no significant differences with respect to the recurrence rate for patients who were immobilized for <1 week compared with those who were immobilized for >3 weeks (41% vs. 37%, p>0.05). Hovelius et al. [8] reported that the duration of immobilization did not significantly affect recurrent dislocation or the need for surgery at any time point in any age subgroup.

Although there is no significant evidence currently showing that immobilization decreases the risk of recurrent instability, it is recommended to immobilize patients for 1 to 3 weeks for comfort, particularly in younger athletic population. However, due to the risk of stiffness and frozen shoulder, immobilization should not exceed 2 weeks in middle-age and elderly patients [36].

Itoi et al. [39] have reported that when the shoulder is immobilized in external rotation, the musculotendinous complex of the subscapularis will become taut, thereby closing the anterior joint cavity and reducing the labrum back to the glenoid rim. They have subsequently hypothesized that external rotation immobilization may improve healing of Bankart lesion in vivo and reduce the rate of recurrent instability due to a more anatomic positioning [40]. In a prospective, multicenter randomized clinical trial, which included 198 patients with a first-time dislocation, the recurrence rate in the external rotation group (26%) was found to be significantly lower than that in the internal rotation group (42%). In the subgroup of patients aged 30 years or younger, the relative risk reduction was 46.1% [41]. According to a recent meta-analysis comparing the position and duration of immobilization after first-time anterior shoulder dislocation, the external rotation immobilization could not reduce the rate of recurrence or improve the quality of life compared with the internal rotation immobilization [42].

Other authors have found no significant difference in the recurrence rates after immobilization between external and internal rotations in patients with first time shoulder dislocation [42,43]. Further research is required in this area to improve the outcomes after shoulder dislocation [43].

Various risk factors at the time of the first episode need to be assessed to establish a treatment protocol. The general consensus in the literature is that young males who are involved in contact sports are at significantly higher risk for recurrent instability than the general population [11,44]. There may be an interaction between sex and other risk factors, such as age or mechanism of injury. For example, young males may be more likely to sustain an instability event during contact sports [45].

Robinson et al. [7] reported survival analysis predicting the recurrent instability for patients between those who did not play sports, those who played noncontact sports, and those who played contact or overhead sports. The recurrent instability rates were 73.3%, 62.8%, and 43.9% at the end of 5 years for patients who played contact or overhead sports, noncontact sports, or no sports, respectively. Olds et al. [46] have suggested that age may be associated with recurrent instability; those under the age of 40 years showed that they may be 13.46 times more likely to suffer from recurrent instability when compared with those over the age of 40 years. They reported a recurrence rate of 51% in patients aged 15 to 20 years, 49% in patients aged 15 to 30 years, 36% in patients aged 21 to 40 years, and 11% in patients older than 40 years [46]. The recurrence rate of anterior shoulder dislocation in patients older than 60 years has been reported to be between 11% and 22% [19,47]. This may be due to the differences in biomechanical properties [48], collagen fiber type, elasticity of the capsule [9], or changes in activity level [49] as a function of age. Another possibility is the tendency to sustain rotator cuff ruptures in older patients, whereas younger patients tend to tear the anterior stabilizing structures and glenohumeral ligaments [47]. Hovelius et al. [8,9] attempted to explain the declining recurrence rate with advancing age on a pathoanatomic basis. They found that the recurrence rate was low when there was an association with tuberosity fracture even in the young. Such fractures are uncommon in younger patients, suggesting that the initial dislocation in young patients disrupts the anterior capsular structures at the glenoid side of the joint, whereas disruption may occur at the humeral side with age. Poor healing in the former impairs the anterior capsular mechanism, predisposing them to recurrence. However there are some older patients who developed instability with multiple recurrent or intractable shoulder dislocations. Levy et al. [47] have reported that a large or massive rotator cuff tear combined with an anterior capsulolabral injury, which was either a Bankart lesion or fracture of the glenoid rim, caused multiple recurrences due to the disruption of the anterior and the posterior stability mechanisms.

Moreover, those with significant bone defect of the glenoid or humeral head, general ligamentous laxity, and ALPSA lesion are at high risk for recurrence following first-time traumatic anterior shoulder dislocation [50-58].