Source: Rachel Liu, BAO, MBBCh, Emergency Medicine, Yale School of Medicine, New Haven, Connecticut, USA

The anterior shoulder dislocation is one of the most common joint dislocations seen in emergency settings. In anterior shoulder dislocation, the humeral head is displaced out of the glenohumeral joint in front of the scapular glenoid, resulting in a loss of the articulation between the arm and the rest of the shoulder. This can be caused by a fall onto an abducted, extended, and externally rotated arm, such as in a bicycle or running accident. Sometimes anterior shoulder dislocation can be due to a minor trauma or even result from rolling over in bed with an externally rotated and stretched overhead arm.

Anterior shoulder dislocation is a painful injury. Patients cannot actively abduct, adduct or internally rotate the shoulder. Reduction of the shoulder is the best form of analgesia and, of course, is necessary to restore arm function. While it is current practice for patients to undergo procedural sedation during the shoulder reduction procedure, the sedatives have serious side effects (cardiac and respiratory depression), and require long stays in the emergency department (ED), dedicated nursing staff, multiple radiographs, and consulting services.

Intra-articular injection with a local anesthetic, such as lidocaine, offers significant pain relief in patients with shoulder dislocations and during the reduction procedure. It is a technically simple procedure that doesn't require long ED stays or significant hospital resources. The success of the intra-articular anesthesia can be enhanced further by performing the procedure under the guidance of bedside ultrasound, which allows real-time visualization of the needle tip reaching the appropriate area.