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Glenohumeral Dislocation
Glenohumeral dislocation occurs when the humeral head exceeds its physiologic limitations, causing it to translate beyond its position in the glenoid rim. It often requires some form of reduction to relocate the humeral head.
Lesser events that are self-limited are termed subluxation or subjective instability.
During these events the humeral head translates too, but not past the glenoid rim to cause a dislocation.
Often the cause of dislocation is traumatic, with the most common direction of humeral head translation being anteriorly and inferiorly.
Some anterior dislocations may cause a tear of the anteroinferior glenoid labrum (Bankart lesion).
Less commonly the head may dislocate posteriorly, such as during seizures or electrocution.
Multidirectional instability predisposes patients to dislocation and is present in a small number of patients.
Frequent subluxations or dislocations may occur in multiple directions and result in excessive joint laxity. They may occur with minimal trauma and are often bilateral.
Symptoms & Clinical Features of Glenohumeral Dislocation
Traumatic:
- •The arm is held in external rotation with anterior dislocation and internal rotation with posterior dislocation.
- •Slight movement is possible without pain.
- •The acromion may appear more prominent, and there may be an absence of the normal “fullness” beneath the acromion.
- •Status of the axillary nerve must always be checked before and after reduction (sensation to the lateral shoulder and ability to gently activate the deltoid).
- •Fractures of the humeral head or glenoid rim may occur and predispose patients to future instability and dislocation events.
Multidirectional:
- •Often present after minimal trauma or with recurrent episodes of “giving out,” weakness, and popping.
- •Sulcus sign may be positive (as the arm is pulled inferiorly with the patient upright, an indentation forms between the acromion and humeral head, indicating excessive inferior movement of the head).
- •Other signs of generalized joint laxity may be present, such as elbow hyperextension, extension of the small finger metacarpophalangeal joint >90 degrees, or flexion of the thumb down to the volar forearm (Beighton criteria).
What causes Glenohumeral Dislocation?
- •Anterior: Due to trauma, often with the arm abducted and externally rotated
- •Posterior: Often secondary to seizure or electrical shock
- •Multidirectional: Secondary to generalized joint laxity
Differential Diagnosis
- •Proximal humerus fracture
- •Grade 3 or greater acromioclavicular (AC) joint injury: Presents with pain and prominent AC joint
Imaging Studies
- •Acute shoulder injury: True anteroposterior (AP) (aimed 15 degrees across the body for a perpendicular view of the glenohumeral joint), scapular “Y” view, and an axillary lateral
- 1.Internal/external rotation variations in the true AP image may reveal bony injury to the proximal humerus.
- •CT: Useful to evaluate fractures of the glenoid and/or humerus. May include contrast arthrogram to evaluate labrum and rotator cuff
- •MRI: Useful to evaluate soft tissue only, including labral injury or rotator cuff tear
Treatment
- •Reduction of the acute dislocation by gentle distal traction in the relaxed patient should be followed by brief immobilization with a sling (less than 1 wk for simple dislocations).
- •Posterior dislocations, inferior dislocations, or fracture-dislocations should be reduced by an experienced practitioner.
- •Gentle limited range-of-motion exercises as pain subsides followed by strengthening exercises at 2 wk.
Disposition
- •Recurrence of anterior dislocation is common in the young population; patients under 30 yr should be referred to an orthopedist for further evaluation.
- •Primary dislocations in patients >40 yr are not generally complicated by recurrence but may result in shoulder stiffness and associated rotator cuff tears.
- •There is an almost 100% recurrence after the third dislocation.
Referral
Surgical reconstruction may be required in patients with recurrent dislocations.
Pearls & Considerations
- •X-rays in two orthogonal planes are always indicated to confirm dislocation or reduction. A single radiograph is never acceptable.
- •It is important to know if there was an injury involved in the first episode and if a radiograph was taken to determine direction of the dislocation.
- •Up to 50% of posterior dislocations are missed by the first examiner, usually the result of an inadequate lateral radiograph of the glenohumeral joint.
- •“Voluntary” dislocators should typically be treated nonsurgically.
- •Sports activities may be resumed when there is pain-free full motion with normal strength.
- •Multidirectional instabilities are usually treated nonsurgically with strengthening exercises and rehabilitation.
- •Dislocations in either direction are occasionally overlooked. If the injury is over 2 to 4 wk old, enough tissue healing will have occurred to make closed reduction nearly impossible. Open surgical reduction may then be needed.
Seek Additional Information
- Gil J.A., et al.: Current concepts in the diagnosis and management of traumatic, anterior glenohumeral subluxations. Orthop J Sport Med 2017; 5 (3): 2325967117694338.
- Kane P et al: Approach to the treatment of primary anterior shoulder dislocation: a review. Phys Sportsmed 43(1):54–64. https://doi.org/10.1080/00913847.2015.1001713.
- Youm T., et al.: Acute management of shoulder dislocations. J Am Acad Orthop Surg 2014; 22 (12): pp. 761-771.