Practice Essentials
The shoulder is the most frequently dislocated joint. It moves almost without restriction but pays the price of stability. The shoulder’s integrity is maintained by the glenohumeral joint capsule, the cartilaginous glenoid labrum (which extends the shallow glenoid fossa), and muscles of the rotator cuff. Most dislocations are anterior, but less frequently, posterior, inferior (luxatio erecta), superior, and intrathoracic dislocations are also possible.
Arthroscopic stabilization is performed in nearly 90% of shoulder stabilization surgeries in the United States.
Patients with shoulder dislocation generally complain of severe shoulder pain and an associated decreased range of motion of the affected extremity.
Shoulder dislocations constitute up to 50% of all major joint dislocations. Anterior dislocations occur in as many as 97% of cases.
Anterior displacement of the humeral head is the most common dislocation seen by emergency physicians and is depicted in the image below.
Y-view radiograph of the right shoulder shows anterior dislocation of the humeral head relative to the glenoid fossa.
Posterior displacement is the next most frequently occurring dislocation (2-4%). Inferior (luxatio erecta), superior, and intrathoracic dislocations are rare (< 1%)and are usually associated with complications.
Anterior dislocation is characterized by subcoracoid position of the humeral head in the anteroposterior (AP) view. 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 on the degree of rotation. The scapular “Y” view reveals the humeral head behind the glenoid (the center of the “Y”). Arteriography, angiography, and Doppler flow studies may be used to evaluate suspected vascular injury. Electromyography (EMG) may be used later to evaluate nerve injuries.
Procedural sedation and analgesia (PSA) protocols, intra-articular lidocaine, and ultrasound-guided brachial plexus nerve block assist in making reduction an easier and more comfortable procedure.
For excellent patient education resources, visit eMedicineHealth’s First Aid and Injuries Center. Also, see eMedicineHealth’s patient education article Shoulder Dislocation.