A pertinent history must be acquired when dealing with shoulder complaints. This includes age, arm dominance, location and intensity of pain, when the injury occurred, aggravating and alleviating factors, radiation of pain, and the mechanism of the injury.

Patients should be fully undressed to expose both shoulders and allow for a complete inspection. Assessment of the range of motion should be performed to evaluate the limits of internal and external rotation along with flexion and extension of the shoulder. Up to 50% of posterior dislocations are missed on the initial evaluation. On exam, assess for any associated neurovascular injuries. Inspection and palpation of the anterior, lateral, and posterior shoulder may show the posterior prominence of the shoulder with the loss of the normal anterior contour along with a prominent coracoid and acromion. The arm is usually adducted with slight internal rotation. Patients will not allow external rotation or abduction secondary to severe pain.

Pre- and post-reduction radiographs are standard when evaluating a shoulder dislocation. When there has been significant trauma, dislocation and fracture-dislocation can have similar findings on physical exam. Post-reduction radiographs are necessary to confirm reduction and rule out any injury or fracture during the reduction procedure. In very select cases of atraumatic chronic dislocation, radiographs may be omitted.

A three view shoulder series is standard when evaluating a painful shoulder. Anterior-posterior (AP) and scapular "Y" view radiographs should be obtained to assess for posterior shoulder dislocations; however, approximately 50% are initially missed on standard AP views. Therefore, the scapular "Y" view can help confirm the diagnosis with the humeral head displaced posterior to the glenoid, with the glenoid being at the center of the "Y" of the scapula.  However this view is sometimes obscured by the soft tissues of the shoulder girdle and the bony anatomy of the scapula and the ribs. The most accurate radiographic image to diagnose a posterior shoulder dislocation is the axillary lateral view. This view eliminates most of the overlying bony and soft tissue structures that could obscure the relationship between the humeral head and glenoid.

On AP views, the normally visualized humerus is internally rotated, this causes the humeral head to appear symmetrical, and it has been compared to the shape of a light bulb or drumstick. A "rim sign" can occur when the space between the articular surface of the humeral head and the anterior glenoid rim exceeds 6 mm; also occasionally seen is a "trough sign", which may appear as a dense line on the medial aspect of the humeral head that represents a compression fracture. Further, it is important to identify if there is a reverse Hill-Sachs deformity which may lead to chronic pain and ultimately to avascular necrosis. [6][7][8][9] These fractures are common with posterior shoulder injuries and represent an impaction fracture of the anteromedial humeral head as it abuts against the glenoid rim during the dislocation injury.

CT scan can be considered when suspected posterior dislocations are not seen on radiographs. More recently bedside ultrasound has also successfully been used to diagnose dislocations with high accuracy, but fracture diagnosis is limited.

Posterior dislocations commonly are associated with severe pain and muscle spasm; therefore, procedural sedation is frequently administered. Intra-articular injections of Lidocaine or Bupivacaine have also been used as an adjunct to pain management to aid in the reduction. Closed reduction is accomplished with in-line traction on the affected arm, which lies internally rotated and adducted. The traction along with gentle, anteriorly-directed manipulation of the humeral head, will help guide it into the glenoid sulcus. Counter-traction can be applied with a sheet around the affected axilla. Forceful external rotation should be avoided as this can put undue stress on the proximal humerus, leading to fracture. The successful reduction is evident when a "clunk" is felt as the joint is reduced, pain is relieved, and range of motion allows the patient to place the palm of the injured arm on the opposite shoulder. If unsuccessful, orthopedic consultation is indicated for closed reduction, and at times, open reduction.

Once reduction is accomplished, reassess the neurovascular status. Post-reduction radiographs are useful for confirmation and documentation of successful reduction and diagnosis of any injuries occurring during the reduction procedure. Patients should have their shoulder immobilized with a sling or shoulder immobilizer in external rotation and slight abduction for a few weeks.  Early orthopedic follow-up is necessary to ensure proper healing, early range of motion, and rehabilitation.

In cases that are diagnosed late or are more chronic, orthopedic consultation is indicated because these patients often require semi-elective open reduction and internal fixation or even arthroplasty. Early operative repair may decrease the incidence of recurrence as well.[10][11][12]

• Acromioclavicular joint injury 

• Bicipital tendonitis 

• Clavicle fractures

• Rotator cuff injury 

• Shoulder dislocation 

• Swimmer's shoulder

Complications of any shoulder dislocation include fracture and neurovascular injury. However, in contrast to anterior dislocations, neurovascular injuries are less common due to the anterior location of the neurovascular structures and the posterior location of the humeral head in this type of dislocation. Soft tissue injuries such as rotator cuff tears are also common, especially in the elderly. Reverse Hill-Sachs deformities, reverse Bankart lesions, and glenoid rim fractures are associated with an increased incidence of recurrence and prolonged recovery. Proper referral to an orthopedist or specialist in shoulder injury should be ensured to avoid the long-term complications that can be associated with posterior shoulder dislocations.

Posterior shoulder dislocation are often managed by an inter-professional team that includes an orthopedic nurse, emergency department physician, orthopedic surgeon and a trauma surgeon. While the diagnosis is relatively simple, sometimes those injuries are missed and present late, and can have a profound impact on the patient's function. Healthcare workers need to be aware of the potential complications which include fracture and neurovascular injury. In addition, patients may develop soft tissue injuries such as rotator cuff tears, especially in the elderly, and these need to be promptly recognized and addressed to reduce the risk of long-term disability. Recurrence of posterior shoulder dislocation can occur and is often associated with prolonged recovery.

Proper referral to an orthopedist or specialist in shoulder injury should be ensured to avoid the long-term complications that can be associated with posterior shoulder dislocations.[13]