Shoulder Dislocation in Emergency Medicine Workup

Updated: Sep 04, 2016
  • Author: Sharon R Wilson, MD; Chief Editor: Trevor John Mills, MD, MPH  more...
  • Print
Workup

Imaging Studies

Radiographs

Anterior dislocation is characterized by subcoracoid position of the humeral head in the anteroposterior (AP) view. Management of anterior shoulder dislocation starts with an analysis of the causative mechanism and a physical exam to establish the diagnosis, and the case can be classified as simple or accompanied by complications (most notably vascular or nerve injuries). Two radiographs perpendicular to each other can confirm the diagnosis and should then be repeated after reduction. Additional imaging studies may be necessary to assess bony lesions (eg, impaction lesions or fractures). [15, 16]

The dislocation is often more obvious in a scapular view, where the humeral head lies anterior to the "Y." In an axillary view, the "golf ball" (ie, humeral head) is said to have fallen anterior to the "tee" (ie, glenoid). In posterior dislocation, the AP view may show a normal walking stick contour of the humeral head, or it may resemble a light bulb or ice cream cone, depending upon the degree of rotation. The scapular "Y" view reveals the humeral head behind the glenoid (the center of the "Y"). In an axillary view, the "golf ball" falls posteriorly off the "tee." [9, 17, 18]  In inferior dislocation (luxatio erecta), the AP view may show the arm raised over the head with the radial head inferior to the glenoid.

Prereduction films are commonly performed to document the nature of the dislocation and to establish the existence of any associated pathology, such as a Hill-Sachs lesion or other humeral fractures. In cases where patients have experienced repeated anterior dislocations, prereduction films may not be necessary prior to attempts at reduction. [19]

Postreduction films confirm relocation of the humerus and may reveal new or previously obscured pathology. Postreduction immobilization is imperative. A prospective observational study examined whether postreduction radiographs add clinically important information to what is seen on prereduction radiographs in patients with anterior shoulder dislocations who are seen in the ED. The authors found that, although most fractures (62.5%) were seen on prereduction radiographs, more than one third (37.5%) were only visible on postreduction films. None of the missed fractures changed ED management, and no persistent dislocations were found on postreduction films. [20]

Other imaging

Arteriography, angiography, and Doppler flow studies may be used to evaluate suspected vascular injury. Electromyography (EMG) may be used later to evaluate nerve injuries. [21]

In a study of computed tomography for the detection of Hill-Sachs lesions, 142 shoulders were evaluated preoperatively by CT (30 with primary instability and 112 with recurrent instability) before arthroscopic Bankart repair. Hill-Sachs lesions were detected in 90 shoulders by initial CT evaluation and were found in 118 shoulders at arthroscopy. In patients with primary subluxation, the prevalence of Hill-Sachs lesions was 26.7%; primary dislocation, 73.3%; and all shoulders, 56.3%. In patients with recurrent episodes of complete dislocation, the prevalence of Hill-Sachs lesions was increased, and the lesions were larger. [10]

Horst et al used magnetic resonance imaging to identify the correlation between Bankart and Hill-Sachs lesions in 105 patients with anterior shoulder dislocation. They found that the co-occurrence of injuries was high [odds ratio (OR) = 11.47; 95% confidence interval (CI) = 3.60-36.52; P < 0.001] and that Bankart lesions co-occurred more often with large Hill-Sachs lesions (O  = 1.24; 95% CI = 1.02-1.52; P = 0.033). In addition, patients older than 29 years more often presented with a bilateral injury (OR = 16.29; 95% CI = 2.71-97.73; p = 0.002). If either lesion was diagnosed, the patient was 11 times more likely to have suffered the associated injury. [11]

Magnetic resonance angiography has been shown to have a high sensitivity when used to identify associated injuries in shoulder dislocation. [22]

In a study of point-of-care ultrasonography for shoulder dislocation in emergency departments, sensitivity and specificity for identifying dislocation were both 100%. For excluding shoulder fracture, point-of-care ultrasound had a sensitivity of 100% and a specificity of 84.2%. [23]

Next:

Procedures

The key to a successful reduction is slow and steady application of a maneuver with adequate analgesia and relaxation.

Procedural sedation and analgesia (PSA) protocols in the ED assist in relaxing the musculature of the shoulder and make reduction a more comfortable and easier procedure. (For further information, see Procedural Sedation.)

Other adjuncts to facilitate reduction for patients who are high risk or may not be candidates for PSA include intra-articular lidocaine and ultrasound-guided interscalene (lidocaine) block of the brachial plexus.

Successful reduction is evidenced by marked reduction in pain and increased range of motion. A palpable or audible relocation ("clunk") may also be noted.

The patient may be asked to touch the uninjured shoulder to safely demonstrate a successful reduction.

Some authors recommend an orthopedic consultation prior to reduction of posterior and inferior dislocations.

After the completion of all reductions, apply a shoulder immobilizer with a sling and swathe. A careful neurovascular examination must be performed prereduction and postreduction.

Post-reduction radiography is still recommended, especially if the procedure was difficult.

Inappropriate traction and poor technique can result in complications with otherwise safe methods of reduction. The Kocher method has been discouraged because of the increased incidence of complications. When performed correctly, it does not involve traction and has been demonstrated to be a safe technique. Reduction of an anterior dislocation may include the following: (For further information, see Joint Reduction, Shoulder Dislocation, Anterior.)

In Kocher's original method, bend the arm at the elbow, press it against the body, rotate outwards until resistance is felt. Lift the externally rotated upper part of the arm in the sagittal plane as far as possible forwards and finally turn inwards slowly.

The Stimson technique requires that the patient lie prone on the bed with the dislocated arm hanging over the side. Traction is provided by up to 10 kg of weight attached to the wrist or above the elbow. Apply gentle internal/external humeral rotation. Reduction may take 20-30 minutes.

In the external rotation method, while the patient lies supine, adduct the arm and flex it to 90° at the elbow. Slowly rotate the arm externally, pausing for pain. Reduce the shoulder before reaching the coronal plane. Often successful, this procedure requires only one physician and little force (see Special Concerns).

For traction-countertraction, while the patient lies supine, apply axial traction to the arm with a sheet wrapped around the forearm and the elbow bent at 90°. An assistant should apply countertraction using a sheet wrapped under the arm and across the chest while the shoulder is gently rotated internally and externally to disengage the humeral head from the glenoid.

Scapular rotation is a less traumatic technique and has success rates of more than 90% in experienced hands, often without sedation. With the patient lying prone, apply manual traction or 5-15 lb of hanging weight to the wrist. After relaxation, rotate the inferior tip of the scapula medially and the superior aspect laterally. Alternatively, the patient can be seated while an assistant provides traction-countertraction by pulling on the wrist with one hand and bracing the upper chest with the other. The same scapular rotation is then performed.

For reduction of a posterior dislocation, apply gentle, prolonged axial traction on the humerus. Then, add gentle anterior pressure while coaxing the humeral head over the glenoid rim. Slow external rotation may be needed.

For reduction of an inferior dislocation, maintain gentle axial traction on the humerus while gentle abduction is applied. Apply countertraction across the ipsilateral shoulder. Following reduction, slowly adduct the arm. Buttonholing of the humeral head through the capsule usually requires open reduction.

Previous