Wiler, Jennifer L. MD, MBA
A 27-year-old woman with a history of seizures and one previous shoulder dislocation complains of shoulder pain. She claims she was taking off her shirt and developed acute onset of right shoulder pain and inability to flex her shoulder.
This is what the radiograph demonstrates.
What is the diagnosis and treatment? See next page.
The shoulder is the most mobile joint in the body, and by design is inherently unstable. (Clin Sports Med 2004;23:335.) That flexibility means the shoulder can dislocate anteriorly, posteriorly, or inferiorly, and the glenohumeral joint of the shoulder is the most commonly dislocated joint in the body, of which 95% are anterior dislocations. (Ann R Coll Surg Engl 2009;91:2.)
The articulation between the humerus and distal scapula border (known as the glenoid) is a ball-and-socket design stabilized by a fibrocartilaginous ring (labrum), ligaments (superior, middle, and inferior glenohumeral and coracohumeral), and muscular components.
The mechanism of dislocation is forceful external rotation while in abduction, and that dislodges the humerus from the glenoid frame anteriorly, and it becomes positioned beneath the coracoid process (75%), clavicle, or glenoid resulting in an avulsion of labrum from the anterior inferior glenoid with an associated tear in the labrum (Bankart lesion). (Br J Surg 1938;26:23.)
The humerus can collide with the anterior glenoid rim as it dislocates, creating a dent in the posterior humeral head (Hill-Sachs lesion), which is found in 54 percent of anterior dislocations. (J Bone Joint Surg Am 1996;78:1677.) The humeral head is forced out of the glenoid in acute anterior dislocations. A dislocation is disassociation of the humeral head from the glenoid fossa, which often requires manual reduction.
Anterior shoulder dislocations are most common in young male athletes after a high-velocity, direct-contact trauma. Glenohumeral joint instability, however, can also result from chronic repetitive microtrauma, congenital abnormalities (Orthop Clin North Am 2001;32:463), or connective tissue disorders. Repeat dislocations or subluxations can result in a chronically unstable joint, which is prone to dislocation after minimal trauma.
The emergency physician should obtain a history that includes patient handedness, vocation, recent trauma, and previous dislocations or subluxations and if manual reduction was required. Patients with baseline glenohumeral joint instability may complain of shoulder pain, popping, catching, locking, a “loose” sensation, stiffness, and swelling. (Clin Sports Med 2000;19:331.)
The clinical presentation of an anterior shoulder dislocation may or may not be clinically obvious. Patients may demonstrate anterior shoulder fullness by a palpable dimple in the skin beneath the acromion. Typically, the patient supports the injured arm close to the body, abducted and slightly externally rotated, with range of motion limited by pain. The patient classically cannot adduct or internally rotate the shoulder.
Axillary nerve injury is not uncommon (10%), and is more common in older patients. (Clin Sports Med 2004;23:335.) Depending on the extent of abduction of the arm and flexion at the elbow, the brachial plexus can also be injured. (J Orthop Trauma 1990;4:121.) The nerve most often injured is the axillary (42%), followed by the radial (7%), with the probability of nerve injury doubled when associated with a concomitant fracture. (Eur J Emerg Med 2006;13:233.)
Radiographs are necessary to rule out associated fractures. Complications of greater tuberosity fractures are rare (<1%) (Ann Vasc Surg 2000;14:110), but associated axillary arterial injuries have been noted, most commonly in atherosclerotic elderly patients. (Orthop Clin North Am 2000;31:231.) Signs of distal vascular compromise may be difficult because of good collateral circulation of the upper extremity, but requires definitive diagnosis by CT angiography if suspected to rule out arterial transaction or dissection versus vasospasm. (Ann R Coll Surg Engl 2009;91:2.) MRI is reserved for preoperative evaluation of the ligaments, nerves, and joint capsule. (Radiology 1996;200:519.)
Closed reduction should be performed as quickly as possible in all patients with an acute dislocation that does not spontaneously reduce. A pre-reduction x-ray should be obtained to identify any fracture fragments that may impede manual reduction. The initial radiographs should include anteroposterior, axillary lateral view, and scapular “Y” views. No consensus exists about the optimal reduction technique or sedation practice. Most recommend procedural sedation, but a few studies have advocated using intra-articular lidocaine, particularly for those patients where sedation may be risky or not optimal. (Am J Emerg Med 1999;17:566; J Bone Joint Surg Am 2002;84-A:2135.)
Many techniques have been described to reduce an anteriorly dislocated shoulder, with limited data to support the optimal method. (Sports Med Arthrosc 2006;14:192.) The decision about which technique to use depends on a number of factors, including the availability of an assistant, patient discomfort, ability to position the patient prone on bed, and operator preference.
Reduction techniques that have been successful are scapular manipulation, the external rotation method, Stimson technique (patient placed prone with 10-15 pound weight attached to wrist of affected arm), Milch (reaching up to pull an apple from a tree), traction-countertraction, and the Spaso technique (patient lays supine with arm lifted with gentle traction to 90 degrees of flexion at the shoulder, then shoulder externally rotated). (Roberts JR, Hedges JR: Clinical Procedures in Emergency Medicine, 4th ed, Philadelphia: Saunders, 2004.)
It is important that the emergency physician document the neurovascular examination before manual reduction or manipulation to distinguish between pre-existing injury and possibly unavoidable, iatrogenic injury. A review of the literature reveals no consensus on whether immobilization is helpful or what the optimal duration of immobilization may be after an initial dislocation. (Clin Sports Med 2004;23.) Some recent studies suggest that immobilization in external rotation may be of some benefit. (J Shoulder Elbow Surg 2003;12:413.) Immobilization has not been shown to decrease the rate of recurrence, and is done only for comfort. (Phys Med Rehabil Clin N Am 2004;15:575.) Ice and analgesics should be prescribed for initial pain control.
Recurrent dislocation is common (as high as 95% in patients under age 20) despite appropriate treatment, and is thought to be the result of capsular laxity. (Ann R Coll Surg Engl 2009;91:2.) Immediate orthopedic consultation is required if reduction is not achieved in the ED or for any dislocation associated with a fracture. (Prim Care 2006;33:751.) At this time, orthopedists have not yet agreed on the optimal definitive therapy (open or arthroscopic operative versus nonoperative). (J Bone Joint Surg Am 2007;89:244; Cochrane Database Syst Rev 2006 Jan 25;:CD004962.)
This patient had an atypical presentation of an anterior dislocation with an inability to adduct the shoulder. She was reduced using procedural sedation in the ED without incident, and has since followed up with orthopedics for a preoperative evaluation including a fluoroscopic-guided arthrogram for MRI.
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