Subluxation (partial dislocation) or dislocation occurs when the humeral head is displaced from the glenoid fossa of the shoulder
Shoulder is prone to subluxation/dislocation because of its inherent instability, particularly anteriorly (90% of subluxations/dislocations occur anteriorly)
RISK FACTORS
Prior shoulder subluxation or dislocation
Contact sports in adolescents
PATHOPHYSIOLOGY/ETIOLOGY
Anterior dislocation usually occurs when a force is applied to an arm in an abducted, extended, and externally rotated position or an anteriorly directed force to the back of the shoulder
Posterior dislocations may be due to a direct blow to the anterior aspect of the shoulder, an indirect force with the arm in flexion, adduction, and internal rotation, or a massive muscle contraction, as occurs with an electrical shock or seizure.
Some children can voluntarily dislocate their shoulder due to increased joint laxity. They will often not be in severe pain and reduction can be achieved without much or any analgesia.
COMMONLY ASSOCIATED CONDITIONS
Up to 35% of first-time anterior dislocations are associated with axillary nerve neuropraxia manifesting as decreased sensation over the deltoid.
DIAGNOSIS
HISTORY
Plausible mechanism (above)
Complaint of acute pain, made worse with any attempt at movement
PHYSICAL EXAM
Obvious deformity with a prominent acromion and flattening of the contour of the lateral upper arm
For anterior dislocation the arm is typically held in slight abduction and external rotation, and the humeral head is palpable anteriorly, with a defect inferior to the acromion
In posterior dislocation the arm is usually held in adduction and internal rotation. There is limited, painful external rotation and abduction and the shoulder will be flattened anteriorly with a prominent coracoid process and posterior appearance
DIAGNOSTIC TESTS & INTERPRETATION
Pathological Findings
Visualization of displaced humeral head
Imaging
AP, lateral and axillary view radiographs
Delaying reduction to acquire imaging if not readily available is not recommended if diagnosis can be determined from history and exam
DIFFERENTIAL DIAGNOSIS
Humeral head fracture
Ligamentous sprain
TREATMENT
MEDICATION
First Line
Pain control with morphine, 0.1mg/kg IV, max 4mg
Second Line
Consider procedural sedation in younger patients if facility is capable, consider ketamine, 1-2mg/kg IV, max 100mg
Older adolescents may tolerate pain medication and intra-articular lidocaine
SURGERY / OTHER PROCEDURES
Fast and atraumatic reduction is the key treatment, there are many methods (see additional reading)
Apply gentle, longitudinal traction through the forearm with the arm abducted and elbow flexed, the arm can be gently internally and externally rotated to help disengage the humeral head. This technique may be applied for 15 to 20 minutes to overcome muscle forces.
Perform a complete neurovascular exam after reduction
Place affected arm in a sling for comfort, instruct to wear for 2-3 weeks
DISPOSITION
Admission Criteria
Surgical management of fracture, all intra-articular fractures require orthopedic evaluation, and most require operative management
Discharge Criteria
Normal neurovascular exam
Pain controlled
Issues For Referral
Unable to reduce
Need for procedural sedation
Associated fracture
FOLLOW UP
FOLLOW-UP RECOMMENDATIONS
Discharge instructions and medications
Pain control with ibuprofen (10m/kg, max 600mg)
Pain should acutely improve after reduction, persistent pain warrants re-evaluation
Activity
As tolerated with arm in sling for 2-3 weeks
Patient Monitoring
Follow-up with pediatrician or sports medicine specialist in 1-2 weeks
Rockwood, CA. Rockwood and Wilkins’ Fractures in Children. 7th ed. Wolters Kluwer/Lippincott, Williams & Wilkins, 2010.
ADDITIONAL READING
Cochrane Review of Conservative Management: Hanchard NC et al. Conservative Management Following Closed Reduction of Traumatic Anterior Dislocation of the Shoulder. Cochrane Database System Review. April 2014.
See Also (Topic, Algorithm, Electronic Media Element)
