Working Diagnosis:
Left shoulder anterior glenohumeral dislocation without evidence of fracture.

Treatment:
Following a discussion regarding reduction options between conscious sedation versus a regional block, the patient opted for a regional block. An interscalene block was then performed, using a bedside ultrasound. The carotid artery was first identified Case Photo #7 Case Photo #8 . Next, the ultrasound probe was moved posterolaterally until the roots of the brachial plexus were identified Case Photo #3 Case Photo #4 . Under direct ultrasound visualization, 20 milliliters of 2% lidocaine without epinephrine was infiltrated around the nerve roots using a 22 gauge needle Case Photo #5 Case Photo #6 . Concurrently, a nasal cannula with 3 liters oxygen flow was secured onto the patient in anticipation of left diaphragmatic hemiparesis. Ten minutes following the injection, the patient noted subjective shortness of breath but had a normal exam. Shoulder reduction was successful using Matsen's traction-countertraction maneuver with no additional complication.

Outcome:
Following the shoulder reduction, the patient was fitted with a sling. Post-reduction x-rays confirmed appropriate humeral articulation with the glenoid, and no fractures were present. He was monitored for approximately one hour with serial neurovascular checks to ensure he remained stable. Once he regained sensory function, he was instructed to keep the affected arm in the sling, and was discharged home with an orthopedic follow-up visit scheduled within three days. A second, two week follow up visit was completed via telephone call at which point the patient informed the medical staff that he had slowly weaned out of the sling and had been cleared by orthopedics to gradually progress back into sports.

Author's Comments:
Peripheral nerve blocks can serve to eliminate the need for procedural sedation while still providing adequate anesthesia during painful procedures. An ultrasound guided interscalene block not only administers adequate anesthesia and muscle relaxation for shoulder reduction, but also provides rapid analgesia, a quick recovery, and maintains patient alertness. An additional benefit to this procedure is that time of recent food consumption is not a limiting factor whereas it can be a contraindication if considering moderate conscious sedation.

It is critical, however, to obtain a careful and thorough past medical history prior to determining if an interscalene block is a reasonable option. Ipsilateral phrenic nerve block and diaphragmatic hemiparesis is a well known and almost inevitable event when performing these blocks. Caution must be taken with patients with pre-existing pulmonary pathology, as it can result in a temporary 25% reduction in pulmonary function. Furthermore, the recurrent laryngeal nerve may be blocked, resulting in complete airway obstruction in anyone who already has a vocal cord palsy. Additional risks include a misguided needle which can result in a pneumothorax, nerve damage, or local anesthetic toxicity.
We used the Matsens traction-countertraction maneuver to reduce this anterior shoulder dislocation. This maneuver consists of the patient lying in a supine position with a sheet around his thorax and also around the waist of the assistant standing at the contralateral side of the affected shoulder. A second sheet is wrapped around the waist and forearm of the practitioner standing on the side of the dislocated shoulder near the waist of the patient while holding the elbow of the patient in 90 degrees of flexion and the shoulder in 90 degrees of abduction. The practitioner applies traction to the affected arm by leaning backwards while the assistant provides countertraction. Other methods, such as Kocher Techniques, Eskimo Approach, and Spaso Technique, are alternative reduction methods commonly used.
When addressing a shoulder reduction, one must look for Hill-Sachs or Bankart lesion on x-ray film. A Hill-Sachs lesion is a humeral head bony defect that is frequently associated with recurrent anterior shoulder instability. In fact, it has been demonstrated that the Hill-Sachs lesion is quite common, appearing in 67 % to 93% of anterior dislocations and up to 100% in patients with recurrent anterior shoulder instability. Bankart lesions, on the other hand, are injuries that occur specifically at the anteroinferior aspect of the glenoid labral complex - also a common complication of anterior dislocations. They are commonly seen in conjunction with a Hill-Sachs defects.

It is important to educate any patient regarding the high rate of recurrent dislocation following relocation. Following a traumatic dislocation, there is a nearly 40% chance of recurrence, particularly if the patient is under the age of 40.

Editor's Comments:
An interscalene injection has been used as an alternative to conscious sedation for shoulder dislocation in the emergency department as well as in the outpatient setting. The injection anesthetizes most of the brachial plexus while sparing the inferior trunk. This provides adequate analgesia and muscle relaxing effects to the area of the shoulder and proximal humerus.

The most common side effects and complications include a phrenic nerve block causing difficulty breathing, a pneumothorax, and potentially Horner syndrome. Using low volumes of anesthetic and bedside ultrasound can minimize the risk of these adverse outcomes.

Contraindications to interscalene injection include suspected axillary nerve injury and preexisting respiratory disease such as asthma or chronic obstructive pulmonary disease.

In the hospital setting, it is important to obtain x-rays prior to as well as following the shoulder reduction to confirm appropriate bony alignment and to confirm no underlying fracture.

References:
Alkaduhimi H, van der Linde JA, Flipsen M, van Deurzen DF, van den Bekerom MP. A systematic and technical guide on how to reduce a shoulder dislocation. Turk J Emerg Med. 2016;16(4):155-168.

Bhoi S, Chandra A, Galwankar S. Ultrasound-guided nerve blocks in the emergency department. J Emerg Trauma Shock. 2010;3(1):82-88.

Blaivas M, Lyon M. Ultrasound-guided interscalene block for shoulder dislocation reduction in the ED. Am J Emerg Med. 2006 May;24(3):293-6.

Fox JA, Sanchez A, Zajac TJ, Provencher MT. Understanding the Hill-Sachs Lesion in Its Role in Patients with Recurrent Anterior Shoulder Instability. Curr Rev Musculoskelet Med. 2017 Dec;10(4):469-479.

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