Shoulder Dislocations Overview

Etiology

The shoulder joint is the most regularly dislocated joint in the body. The shoulder can dislocate forward, backward, or downward, and completely or partially, though most occur anteriorly. Fibrous tissue that joins the bones can be stretched or torn, complicating a dislocation. It takes a strong force, such as a blow to the shoulder to pull the bones out of place. Extreme rotation can pop the shoulder out of its socket. Contact sports injuries often cause a dislocated shoulder. Trauma from motor vehicle accidents and falls are also a common source of dislocation.[4][5][6][7]

Epidemiology

The shoulder is the most regularly dislocated joint in the body; the dislocation may anteriorly, posteriorly, inferiorly, or anterior-superiorly. Anterior locations are the most common. Patients with prior shoulder dislocation are more prone to redislocation. Reoccurance occurs because the tissue does not heal properly or it becomes lax. Younger patients have a much higher frequency of redislocation; most like due to higher activity level. Patients who tear their rotator cuffs or fracture the glenoid also have a higher incidence of redislocation.

Pathophysiology

Types of Dislocation[5][8][9][10]

Anterior dislocation is the most common, accounting for up to 97% of all shoulder dislocations.

• Mechanism of injury is usually a blow to an abducted, externally rotated and extended extremity.
• It may also occur with posterior humerus force or fall on an outstretched arm.
• On exam, the arm is usually abducted and externally rotated, and the acromion appears prominent
• There are associated injuries in up 40% of anterior dislocations including nerve damage, or tears and fractures associated with the labrum, glenoid fossa, and/or humeral head.

Posterior dislocations account for 2% to 4% of shoulder dislocations.

• Usually, the injury is caused by a hit to the anterior shoulder and axial loading of the adducted internally rotated arm.
• It may also be a result of violent muscle contractions (seizures, electrocution).
• On exam, the arm is usually held in adduction, and internal rotation and patient is unable to rotate externally.
• Higher risk of associated injuries such as fractures of surgical neck or tuberosity, reverse Hill-Sachs lesions (also called a McLaughlin lesion which is an impaction fracture of anteromedial aspect of humeral head), and injuries of the labrum or rotator cuff.

Inferior dislocations (also known as luxatio erecta) are the most uncommon type (less than 1%).

• Usually caused by hyperabduction or with axial loading on the abducted arm.
• On exam, the arm is held above and behind the head and patient is unable to adduct arm.
• Often associated with nerve injury, rotator cuff injury, tears in the internal capsule, and the highest incidence of axillary nerve and artery injury of all shoulder injuries.

History and Physical

History

Patients may report:

• A popping sensation
• Sudden onset of pain with decreased range of motion
• The sensation of joint rolling out of the socket.

Remember to ask about any previous dislocations. When the shoulder dislocates, the nerves can get stretched out. Some patients report stinging and numbness in the arm at the time of the dislocation.

Physical

The physical examination should confirm a suspected dislocation.

• Range of motion is diminished and painful
• Anterior dislocation, the anterior arm is abducted and externally rotated In thin patients, there may be a prominent humeral head felt anteriorly, and the void can be seen posteriorly in the shoulder
• Posterior dislocations are easy to miss because the arm is in internal rotation and adduction. In thin patients, the prominent head can be palpated posteriorly. Practitioners can miss posterior shoulder dislocations because the patient appears only to be guarding the extremity.

Performing a detailed neurovascular examination before reduction is imperative. Injury to the axillary nerve during shoulder dislocation is as high as 40%. Practitioners should record the neuromuscular examination before and after any dislocated shoulder.

Evaluation

Diagnosis and Management

Carefully examine the patient for neurovascular compromise. Axillary nerve injury is most common. The axillary nerve innervates deltoid and teres minor and provides sensation to lateral shoulder. Axillary nerve compromise presents in over 40% of dislocations, but usually, resolves with reduction. Although dislocation is often obvious, pre-reduction imaging for associated fractures can be useful and should be done when trauma is known. Clinically important fractures occur in about 25% of dislocations.[11][12]

• Fractures of tuberosity, surgical neck fractures may occur and should not be reduced in emergency department
• Bankart lesion develops when the glenoid labrum is disrupted with or without the addition of avulsed bone fragment (bony Bankart). Soft Bankart lesions involving the inferior anterior labrum are more common.
• Hill-Sachs deformity is a compression fracture of the posterolateral humeral head primarily with anterior dislocations.
• Reverse Hill-Sachs lesions seen in posterior dislocations (also called a McLaughlin lesion) which is an impaction fracture of the anteromedial aspect of the humeral head.

Reduction of the Dislocated Shoulder

Often conscious sedation with fentanyl, midazolam, ketamine, etomidate, or propofol used. This is done with continuous monitoring with capnography. If conscious sedation not needed, an intraarticular injection of 10 cc of local lidocaine or similar anesthetic may be helpful.

Contraindications to reduction in ED

Anterior Dislocation

• Fractures of humeral neck can lead to avascular necrosis
• Subclavicular and/or intrathoracic dislocations include a subacute dislocation in an elderly patient and an associated surgical neck fracture
• Avoid multiple attempts in injuries that include neurovascular compromise (including brachial plexus involvement, axillary nerve, a musculocutaneous nerve, etc.).  If prompt reduction cannot occur without further injury, may need surgical help.  
• The suspected arterial injury may need urgent angiography first.

Posterior Dislocation

• Delayed presentation to the emergency department (more than 6 weeks)
• Multipart or displaced fracture/dislocations

Inferior Dislocation

• Humeral neck or shaft fractures should be done in a surgical setting
• Any potential of vascular injury

Treatment / Management

Reduction techniques for anterior shoulder dislocation

Scapular Manipulation  (80% to 100% successful)

• Upright or prone
• In upright position, the patient is sitting up, may rest unaffected shoulder against upright head of bed
• Stand behind patient and use one thumb over tip of scapula and push medially while pushing acromion inferiorly with the other thumb
• Assistant simultaneously provided traction by grabbing patient’s wrist with one hand and flexed elbow with other hand and pushing down on elbow
• The reduction may be subtle, without obvious “clunk.”
• Reduced risk of associated fractures

External Rotation Technique 

The external rotation technique reduces anterior glenohumeral dislocation by overcoming spasm of the internal rotators of the humerus, unwinding the joint capsule, and enabling the external rotators of the rotator cuff to pull the humerus posteriorly.

• Easy and can do alone
• With patient supine, elbow flexed to 90 degrees, elbow held with one hand, and wrist is held with another hand
• Slowly, have patient allow the arm to fall to the side, externally rotating forearm. The patient pauses with pain and allows muscles to relax. Over 5 to 10 minutes, the arm externally rotates, and reduction occurs
• Reduction usually occurs with arm externally rotated between 70 to 110 degrees

Cunningham Technique

• Patient is seated with examiner seated in front of patient, and the patient places ipsilateral hand on top of examiner’s shoulder
• The clinician rests one arm in patient’s elbow crease and uses the other hand to massage the patient’s biceps, deltoid, and trapezius muscles
• Have patient relax and instruct to pull their shoulder blades together and straighten their back
• Popular technique now since rarely conscious sedation needed

Milch Technique  (add Milch technique if external rotation unsuccessful)

• Patient is supine, fingers over the shoulder with thumb in axilla to stabilize
• Arm is externally rotated and then abducted over patient’s head while maintaining external rotation with simultaneously placing direct pressure over the humeral head

Stimson Technique

• No assistant needed and no need for conscious sedation
• Patient is prone with affected arm hanging off the side of bed with 5 lb (2.3 kg) to  15 lb (6.8 kg) of weight
• Reduction is usually achieved within 30 minutes

Traction Countertraction

• A sheet is wrapped under the axilla, and one assistant provides continuous traction at the wrist or elbow while the other provides countertraction with the sheet from the opposite side

Spaso Technique

• Patient is supine while examiner grasps wrist or distal forearm and lifts vertically with gentle vertical traction and external rotation

Fares Technique

• Patient is supine with upper extremity at their side
• The examiner holds patient’s wrist and gently pulls the arm to provide traction
• The arm is abducted while continuously moving arm in anteriorly and posteriorly in small oscillating movements (about 10 cm)
• If shoulder has not reduced by 90 degrees of abduction, add external reduction

Fulcrum Technique

• Patient is supine or sitting, and a rolled towel or sheet is placed in axilla
• The distal humerus is adducted with simultaneous posterolateral force on the humeral head
• Requires increased force, may have increased complications

Kocher’s and Hippocratic Techniqueoot placed in patient’s axilla before traction) no longer recommended due to higher risk of complications

Posterior Shoulder Reduction

• The patient is in the supine position. An assistant applies anterior pressure to humeral head while examiner applies axial traction to the humerus with internal and external rotation of humerus

Disposition After Shoulder Reduction

• Place patient in a sling
• Neurovascular exam
• Post-reduction imaging
• Follow-up with an orthopedic surgeon

Differential Diagnosis

• Acromioclavicular joint injury

• Bicipital tendonitis

• Clavicle fracture

• Rotator cuff injury

• Shoulder dislocation

• Swimmer’s shoulder