9.05 Shoulder dislocation

agk’s Library of Common Simple Emergencies

Presentation

The patient was holding his shoulder abducted horizontally to the side when a blow knocked the humeral head anteriorly. He arrives holding the shoulder abducted ten degrees from his side, unable to move it without increasing the pain. The delto-pectoral groove is now a bulge (caused by the dislocated head of the humerus) and the acromion is prominent laterally, with a depression below (where the head of the humerus sits on the undislocated shoulder).

What to to:

• Provide analgesia. Ketorolac (Toradol) 60mg im or 30mg iv is good, but you may need intravenous narcotics. To abolish muscle spasm and provide conscious sedation for a difficult reduction, but have the patient awake enough to go home in an hour, one recommended regimen is intravenous midazolam (Versed) 5mg and fentanyl (Sublimaze) 0.1mg, given ten minutes before the procedure, with continuous pulse oximetry, iv fluids running, and the physician by the bedside with bag-valve-mask and endotracheal intubation kit ready. Many shoulders, however, can be reduced without conscious sedation.
• When analgesia is required, another alternative is th use intra-articular lidocaine. After preparing the skin with povidone-iodine, using a 1.5 inch 20 gauge needle, inject 20 mL of 1% lidocaine 2 cm inferiorly and directly lateral to the acromion, in the lateral sulcus left by the absent humeral head.
• If available, obtain a pre-reduction x ray to rule out fractures or unreduceable injuries. This image may be deferred and speed treatment and relief if the injury was recurrent and relatively atraumatic.
• Test and record the sensation over the deltoid to establish if there is an injury of the axillary nerve (rare) and confirm the circulation, sensation, and movement in the elbow, wrist and hand.
• Gain the patient’s confidence by holding his arm securely, asking him to relax, telling him that you will not do anything suddenly and that if any pain occurs you will stop. Then in a very calm and gentle manner ask him to let his muscles go loose so his shoulder can stretch out.
• With the elbow flexed at 90 degrees, apply steady traction at the distal humerus. Pull inferiorly and at the same time externally rotate the forearm very, very slowly. If the patient complains of pain, stop rotating, allow him to relax and let the shoulder muscles stretch while you continue to maintain traction along the humerus. Resume external rotation when he is comfortable again. Using this method, full external rotation alone will reduce most anterior shoulder dislocations.
• If you do not feel or see the shoulder joint reduce, then, while maintaining traction and external rotation, slowly and gently adduct the humerus until it is against the chest wall and then slowly internally rotate the forearm against the anterior chest. The vase majority of shoulder dislocations can be reduced comfortably this way, often without the use of any analgesics.
• An alternative technique when you can palpate the lateral border of the scapula is reduction by scapular manipulation. With the patient sitting up, place the uninjured shoulder firmly against an immovable support such as a wall or the raised head of the stretcher. Have an assistant face the patient and gently lift the outstretched wrist of the affected arm until it is horizontal. The assistant then places the palm of his free hand against the mid-clavicular area of the injured shoulder as counterbalance, and then gently put firmly pulls the patients arm towards him. At the same time manipulate the scapula by adducting the inferior tip using thumb pressure, while stabilizing the superior aspect with your upper hand.
• When the patient is comfortable and range of motion has been restored, secure the reduction in a sling and a swath around the arm and chest. Obtain post-reduction x rays, and discharge the patient once he is alert, with a prescription of analgesics as needed and an appointment for orthopedic follow up in a week (sooner if any problem).

What not to do:

• Do not use the forearm as a lever to fracture the neck of the humerus.
• Do not redislocate the shoulder by repeating the motions of the mechanism of injury.

Discussion

Your strategy is to relocate the shoulder with minimal damage to the joint capsule and anterior labrum of the glenoid fossa, hoping the patient does not become a chronic dislocator with an unstable shoulder. Chronic dislocators are easier to reduce, and come less often to the ED, because they learn how to relocate their own shoulders.

Posterior dislocations are caused by internal rotation of the shoulder, as during a seizure, and are more subtle to diagnose. Subglenoid dislocation or luxatio erecta is rare and unmistakable, with the arm raised and abducted.

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