Shoulder Dislocation/Instability

Key Points:

  • Skeletally immature patients more likely to have proximal humeral fracture than dislocation due to anatomical differences from adults
  • Adolescent and pre-adolescent patients have different injuries, treatments, and outcomes. 
  • Anterior dislocation most common with failure of anterior inferior glenohumeral ligaments. 
  • Axillary nerve most commonly injured neurovascular structure.

Description:

The shoulder is inherently unstable allowing for its large functional range of motion. Traumatic dislocations are rare in children under 10 years old, accounting for less than 2% of dislocations. But, 20% of shoulder dislocations occur in patients under 20 years old. Most literature focuses on treatment of adolescent/skeletally mature shoulder dislocations due to their high recurrence rates. Most dislocations are anterior dislocations. Redislocation rates are reported from 0-100%, highly variable.

Epidemiology:

Clinical Findings:

Must discern between traumatic or atraumatic dislocations, subluxation, or translational event. In skeletally immature patients, anterior-inferior dislocations present with slightly abducted, externally rotated arm. The humeral head may be palpable with a prominent acromion in thin patients. A thorough neurovascular exam including the axillary nerve should be performed. In contrast, posterior dislocations may be subtle on physical exam, with the arm typically held adducted and internally rotated against the patient’s chest.  In reduced glenohumeral joints, physical exam maneuvers include the load and shift test, sulcus sign, and apprehension/relocation tests. Patients should also have Beighton scores completed if concerned about multidirectional instability due to capsular laxity. 

Imaging Studies:

  • Shoulder radiographs with AP and axillary view should be completed in the acute setting or initial office visit. 
  • MRI with or without intra-articular contrast can provide helpful clinical information in subacute and chronic settings. 

Etiology:

Anterior and posterior bands of inferior gleno-humeral ligament resist anterior-posterior humeral translation at 90 degress of abduction and external rotation. Superior glenohumeral ligaments resist at 0 degrees and the middle glenohumeral ligament resists in midrange abduction and external rotation.  The incidence of capsulolabral injury in skeletally immature patients is low and speculated to be due to high elasticity and resilience of tissues. Additionally, the proximal humeral physis is extra-capsular except for the inferomedial physis where the joint capsule attaches more distally along the shaft. Due to this anatomy, humeral avulsions of glenohumeral ligaments (HAGL) are more likely than labral tears in skeletally immature patients. The physis, being weaker than the shoulder ligaments, is more likely to fail in pediatric patients causing a proximal humeral fracture instead of a shoulder dislocation.

Treatment:

Prompt recognition and reduction of acute shoulder dislocations is imperative. Remember the proximal humeral physis closes between ages 14 to 17 years, so gentle, constant traction should be used for reductions in order to avoid injury to the proximal humeral physis. Immobilization in adduction and internal rotation for 1-6 weeks is typical. 

Treatment after primary and recurrent dislocations is controversial. Current evidence favors nonsurgical treatment for primary dislocations in skeletally immature patients given lower recurrence rates than adolescent and adult patients.  Physical therapy for gradual strengthening and return of range of motion can vary depending on the age of the patient.

Surgical intervention is indicated for patients with recurrent dislocation who have failed nonoperative management or primary dislocations at high risk of recurrence due to MRI findings or risk factors such as age, arm dominance, sport, compliance, etc. Patients with multidirectional instability often require a labral repair with capsulorrhaphy. Open, arthroscopic assisted open, and all arthroscopic techniques have been described. 

Complications:

Complications of primary dislocations include associated soft tissue and bony injuries from the dislocation event, recurrent dislocations, and neurovascular injuries.  Axillary nerve injuries are reported in 42% of traumatic anterior shoulder dislocations. Postoperative complications include recurrent dislocation, neurovascular injury, failure of repair, and stiffness. 

References:

  1. Cordischi K, Li X, Busconi B. Intermediate Outcomes After Primary Traumatic Anterior Shoulder Dislocation in Skeletally Immature Patients Aged 10-13 Years. Orthopedics.Sept 2009;32 (9);686-690
  2. Deitch J, et al. Traumatic Anterior Shoulder Dislocation in Adolescents. Am J Sports Med. Sept-Oct 2003;31(5):758-763
  3. Jones K, et al. Functional Outcomes of Early Arthroscopic Bankart Repair in Adolescents Aged 11-18 Years. J Pediatr Orthop. 2007;27:209-213
  4. Lawton RL, et al. Pediatric Shoulder Instability: Presentation, Findings, Treatment and Outcomes. J Pediatr Orthop. 2002;22:52-61 
  5. Li X, et al. Management of Shoulder Instability in the Skeletally Immature Patient. J Am Acad Orthop Surg. 2013;21:529-537

Top Contributors:

Jennifer Beck MD