Dislocated shoulder
The most frequently dislocated joint in the human body.
A dislocated shoulder occurs when the ball of the upper arm bone comes out of its socket in the shoulder blade. This joint is the one most often dislocated in the body, accounting for half of all joint dislocations. People with this injury typically feel pain in the shoulder and a sense that the joint is unstable.
There are several types of shoulder dislocation. The most common by far is an anterior dislocation, which makes up 97% of cases. Posterior dislocations are less frequent, occurring in 2–4% of cases, and inferior dislocations are the rarest, at under 1%. These less common types usually result from a traumatic accident or impact. Dislocations can also be partial (subluxation) or complete.
Anterior dislocations often happen when the arm is forcefully rotated outward and away from the body, especially in sports like swimming and tennis that involve overhead motion. Doctors typically suspect a dislocation based on the person’s symptoms and history, and they usually confirm it with X-rays.
Signs of a dislocation include significant pain that may radiate down the arm, a feeling that the shoulder is slipping out of place during certain movements, and the arm being held in an unusual position—externally rotated for anterior dislocations, or internally rotated and pulled in for posterior ones. The shoulder may look visibly out of place, sometimes appearing square, and there may be numbness in the arm. Movement is generally resisted due to pain.
Diagnosis is often made from the person’s account and a physical exam, with X-rays used to confirm the problem. Most dislocations are obvious on standard X-rays, though posterior ones can be harder to see on a front-facing view. After the joint is put back in place, X-rays are usually repeated to check that the reduction is successful and to look for bone damage. For people with repeated dislocations, an MRI may help assess soft tissue injuries. Tests like the apprehension test (for anterior instability) and the sulcus sign (for inferior instability) can help predict future dislocations.
Complications can include a Bankart lesion (damage to the labrum), a Hill-Sachs lesion (a dent in the humeral head), a rotator cuff tear, or injury to the axillary nerve. Severe cases may also involve fractures of nearby bones.
Quick Facts
- Field
- Emergency medicine, orthopedics
- Symptoms
- Shoulder pain
- Complications
- Bankart lesion, Hill-Sachs lesion, rotator cuff tear, axillary nerve injury
- Types
- Anterior, posterior, inferior, superior
- Causes
- Extreme rotation, traumatic impact
- Diagnosis
- Based on symptoms, X-rays
- Treatment
- Shoulder reduction, arm sling
- Medication
- Procedural sedation and analgesia, intraarticular lidocaine
- Prognosis
- Recurrence common in young people
- Frequency
- 24 per 100,000 per year (US)
Facts from the source article.
Lore & Background
There are multiple types of shoulder dislocation, with anterior dislocation being by far the most common, comprising 97% of all shoulder dislocations. Less common types include posterior (2-4% of all shoulder dislocations) and inferior shoulder dislocation (<1% of all shoulder dislocations), as these latter types tend to involve a traumatic accident and/or impact. Shoulder dislocations can also be divided into subluxation (partial dislocation) or full dislocation. Common causes of anterior shoulder dislocation include extreme rotation, particularly abduction and external rotation of the shoulder. Athletes playing sports that involve overhead extension such as swimming and tennis are susceptible for shoulder dislocation.
Reader's Guide
A dislocated shoulder is a significant medical condition due to its high frequency and potential complications. Diagnosis is typically made based on symptoms and may be confirmed by X-rays. Complications may include a Bankart lesion, Hill-Sachs lesion, rotator cuff tear, or injury to the axillary nerve. Treatment is by shoulder reduction which may be accomplished by a number of techniques, including traction-countertraction, external rotation, scapular manipulation, and the Stimson technique. After reduction X-rays are recommended for verification. The arm may then be placed in a sling for a few weeks. Surgery may be recommended in those with recurrent dislocations. Not all patients require surgery following a shoulder dislocation. There is moderate quality evidence that patients who receive physical therapy after an acute shoulder dislocation will not experience recurrent dislocations. About 1.7% of people have a shoulder dislocation within their lifetime. In the United States this is about 24 per 100,000 people per year. They make up about half of major joint dislocations seen in emergency departments.
Did You Know?
- The shoulder is the most commonly dislocated joint, comprising 50% of all joint dislocations.
- Anterior dislocation accounts for 97% of all shoulder dislocations.
- The axillary nerve is injured in 37% of anterior dislocations, making it the most commonly injured structure.
- About 1.7% of people experience a shoulder dislocation within their lifetime.
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