Intra-articular posterior shoulder injections are as effective as intravenous sedation for treating pain associated with shoulder dislocation.^1,2

Ultrasound guidance increases the accuracy of shoulder injections compared to landmark-based techniques.³

Ultrasound can also confirm dislocation and reduction of the humeral head when landmarks are difficult to palpate.

The anterior technique can be used, but the posterior technique is easier and more effective.⁴

Reduction of a dislocated shoulder

Allergy to anesthetic

Altered or unconscious patient

Infection overlying the area

Neurologic deficit in the affected extremity

Ultrasound machine with a high-frequency linear probe

• Low-frequency curvilinear (1-5MHz) probe might be required for muscular and obese patients

Sterile ultrasound probe cover and gel

Sterile gloves

Skin disinfectant and antiseptic

Bupivacaine or ropivacaine 0.25-0.5% or lidocaine 1-2%

• Always calculate maximum dose, bupivacaine and ropivacaine 3 mg/kg and lidocaine 5 mg/kg

20- to 30-mL syringe

18-gauge needle

Intravenous access

The shoulder is a ball-and-socket joint composed of the humeral head and the glenoid fossa, which arises from the scapula and is lined by a fibrocartilaginous layer, the glenoid labrum.

Anterior shoulder dislocations (common) occur when an external force causes abduction, extension, and external rotation of the humeral head, pushing it inferiorly below the glenoid fossa.

• The pectoralis and biceps muscles subsequently contract and pull the humerus anteriorly to a location just below the glenoid fossa or coracoid.
• The axillary and musculocutaneous nerves are at risk for injury.

Posterior shoulder dislocations (rare) occur when there is forceful internal rotation and adduction of the shoulder.

Have the patient sit facing away from you, with the affected arm at the side in a neutral position. Figure 1

Place the ultrasound machine in front of the patient on the affected side.

Disinfect the skin.

Place a sterile cover over the ultrasound probe and apply sterile gel.

Place the probe in a transverse orientation over the infraspinatus and posterior glenohumeral joint, along the axis of the spine of the scapula and just caudal to the acromion. Figure 2

Identify the humeral head, glenoid labrum, infraspinatus tendon, and joint capsule.

• Normally, the humeral head is located in the glenoid fossa. Figure 3
• In an anterior shoulder dislocation, the humeral head is located in the far field (deep to the probe). Figure 4

Place a skin wheal with local anesthetic lateral to the probe with a small-bore needle.

Enter the skin 1 cm lateral to the probe and advance the needle from the lateral to medial direction.

Keep the probe in a transverse orientation and use an in-plane technique.

Enter the shoulder joint between the posterior glenoid labrum and the insertion of the infraspinatus tendon on the hyperechoic (bright) humeral head.

Accidental puncture or injection into the suprascapular or the circumflex scapular neurovascular structures

Infection

Local anesthetic systemic toxicity

• Always calculate maximum dose (bupivacaine and ropivacaine 3 mg/kg and lidocaine 5 mg/kg).

An ultrasound-guided shoulder injection requires a procedure note in the medical record.

Document:

• Clinical examination before the procedure, including neurologic and vascular examinations of the upper extremity
• Sterile preparation and local antiseptic used
• Needle approach and confirmation of needle placement
• Type and dose of anesthetic injected
• Clinical examination immediately after the procedure
• Complications

Anticoagulation is not a contraindication, but care must be taken to avoid puncturing a deep vessel.

Tell the patient about driving restrictions, work limitations, participation in sports, and so on as appropriate.

ACEP Now: POC ultrasound and shoulder dislocation

ALiEM: “Trick of the trade” on ultrasound-guided shoulder injection

emDocs: Shoulder ultrasound and intra-articular injection

SonoSite: Shoulder injection how-to