Pediatric Glenohumeral Dislocations: Causes, Evaluation, and Treatment
Learn about the epidemiology, anatomy, mechanism, evaluation, and treatment of pediatric glenohumeral dislocations. Explore common complications and discover the best techniques for managing this condition in children.
Epidemiology
Rare in children; Rowe reported that only 1.6% of shoulder dislocations occurred in patients <10 years of age, whereas 10% occurred in patients 10 to 20 years of age.
Ninety percent are anterior dislocations.
Anatomy
The glenohumeral articulation, with its large convex humeral head and correspondingly flat glenoid, is ideally suited to accommodate a wide range of shoulder motion. The articular surface and radius of curvature of the humeral head are about three times those of the glenoid fossa.
Numerous static and dynamic stabilizers of the shoulder exist; these are covered in detail in 14.
The humeral attachment of the glenohumeral joint capsule is along the anatomic neck of the humerus, except medially where the attachment is more distal along the shaft. The proximal humeral physis is therefore extra-articular except along its medial aspect.
As in most pediatric joint injuries, the capsular attachment to the epiphysis renders failure through the physis much more common than true capsuloligamentous injury; therefore, fracture through the physis is more common than a shoulder dislocation in a skeletally immature patient.
In neonates, an apparent dislocation may actually represent a physeal injury.
Mechanism of Injury
- Neonates: Pseudodislocation may occur with traumatic epiphyseal separation of the proximal humerus. This is much more common than a true shoulder dislocation, which may occur in neonates with underlying birth trauma to the brachial plexus or central nervous system.
- Anterior glenohumeral dislocation may occur as a result of trauma, either direct or indirect.
- Direct: An anteriorly directed impact to the posterior shoulder may produce an anterior dislocation.
- Indirect: Trauma to the upper extremity with the shoulder in abduction, extension, and external rotation is the most common mechanism for anterior shoulder dislocation.
- Posterior glenohumeral dislocation (2% to 4%):
- Direct trauma: This results from force applied to the anterior shoulder, dislocating the humeral head posteriorly.
- Indirect trauma: This is the most common mechanism. The shoulder is typically in the position of adduction, flexion, and internal rotation at the time of injury with axial loading.
- Electric shock or convulsive mechanisms may produce posterior dislocation owing to the overwhelming of the external rotators of the shoulder (infraspinatus and teres minor muscles) by the internal rotators (latissimus dorsi, pectoralis major, and subscapularis muscles).
- Atraumatic dislocations: Recurrent instability related to congenital or acquired laxity or volitional mechanisms may result in anterior dislocation with minimal trauma.
Clinical Evaluation
Patient presentation varies according to the type of dislocation encountered.
Anterior Dislocation
The patient typically presents with the affected upper extremity held in slight abduction and external rotation. The acutely dislocated shoulder is painful, with muscular spasm in an attempt to stabilize the joint.
Examination typically reveals squaring of the shoulder caused by a relative prominence of the acromion, a relative hollow beneath the acromion posteriorly, and a palpable mass anteriorly.
A careful neurovascular examination is important with attention to axillary nerve integrity. Deltoid muscle testing is usually not possible, but sensation over the deltoid may be assessed. Deltoid atony may be present and should not be confused with axillary nerve injury. Musculocutaneous nerve integrity can be assessed by the presence of sensation on the anterolateral forearm.
Patients may present after spontaneous reduction or reduction in the field. If the patient is not in acute pain, examination may reveal a positive apprehension test, in which passive placement of the shoulder in the provocative position (abduction, extension, and external rotation) reproduces the patient’s sense of instability and pain. Posteriorly directed counterpressure over the anterior shoulder may mitigate the sensation of instability.
Posterior Dislocation
Clinically, a posterior glenohumeral dislocation does not present with striking deformity; moreover, the injured upper extremity is typically held in the traditional sling position of shoulder internal rotation and adduction.
A careful neurovascular examination is important to rule out axillary nerve injury, although it is much less common than with anterior glenohumeral dislocations.
On examination, limited external rotation (often <0 degrees) and limited anterior forward elevation (often <90 degrees) may be appreciated.
A palpable mass posterior to the shoulder, flattening of the anterior shoulder, and coracoid prominence may be observed.
Atraumatic Dislocation
Patients present with a history of recurrent dislocations with spontaneous reduction.
Often, the patient will report a history of minimal trauma or volitional dislocation, frequently without pain.
Multidirectional instability may be present bilaterally, as may characteristics of multiple joint laxity, including hyperextensibility of the elbows, knees, and metacarpophalangeal joints. Skin striae may be present.
Sulcus sign: This is dimpling of skin below the acromion with longitudinal traction.
Superior and Inferior (Luxatio Erecta) Dislocation
This is extremely rare in children, although cases have been reported.
It may be associated with hereditary conditions such as Ehlers-Danlos syndrome.
Radiographic Evaluation
A trauma series of the affected shoulder is indicated: AP, scapular-Y, and axillary views.
Velpeau axillary view: Compliance is frequently an issue in the irritable, injured child in pain. If a standard axillary view cannot be obtained, the patient may be left in a sling and leaned obliquely backward 45 degrees over the cassette. The beam is directed caudally, orthogonal to the cassette, resulting in an axillary view with magnification.
Special views (see 14)
- West Point axillary view: Taken with the patient prone with the beam directed cephalad to the axilla 25 degrees from the horizontal and 25 degrees medially. It provides a tangential view of the anteroinferior glenoid rim.
- Hill-Sachs view: An AP radiograph is taken with the shoulder in maximal internal rotation to visualize posterolateral defect (Hill-Sachs lesion) caused by an impression fracture on the glenoid rim.
- Stryker notch view: The patient is supine with the ipsilateral palm on the crown of head and the elbow pointing straight upward. The x-ray beam is directed 10 degrees cephalad, aimed at coracoid. One is able to visualize 90% of posterolateral humeral head defects.
Computed tomography may be useful in defining humeral head or glenoid impression fractures, loose bodies, and anterior labral bony injuries (bony Bankart lesion).
Single- or double-contrast arthrography may be utilized in cases in which the diagnosis may be unclear; it may demonstrate pseudosubluxation, or traumatic epiphyseal separation of the proximal humerus, in a neonate with an apparent glenohumeral dislocation.
Magnetic resonance imaging may be used to identify rotator cuff, capsular, and glenoid labral (Bankart lesion) pathology.
Atraumatic dislocations may demonstrate congenital aplasia or absence of the glenoid on radiographic evaluation.
Classification
- Degree of stability: Dislocation versus subluxation
- Chronology: Congenital
Acute versus chronic
Locked (fixed)
Recurrent - Acquired: generally from repeated minor injuries (swimming, gymnastics, weights); labrum often intact; capsular laxity; increased glenohumeral joint volume; subluxation common
- Force:
Atraumatic: usually owing to congenital laxity; no injury; often asymptomatic; self-reducing
Traumatic: usually caused by one major injury; the anteroinferior labrum may be detached (Bankart lesion); unidirectional; generally requires assistance for reduction - Patient contribution: Voluntary versus involuntary
- Direction: Subcoracoid
Subglenoid
Intrathoracic
Treatment
Closed reduction should be performed after adequate clinical evaluation and administration of analgesics and/or sedation. Described techniques include (the figures in 14):
- Traction–countertraction: With the patient in the supine position, a sheet is placed in the axilla of the affected shoulder with traction applied to counter axial traction placed on the affected upper extremity. Steady, continuous traction eventually results in fatigue of the shoulder musculature in spasm and allows reduction of the humeral head.
- Stimson technique: The patient is placed prone on the stretcher with the affected upper extremity hanging free. Gentle, manual traction or 5 lb of weight is applied to the wrist, with reduction effected over 15 to 20 minutes.
- Steel maneuver: With the patient supine, the examiner supports the elbow in one hand while supporting the forearm and wrist with the other. The upper extremity is abducted to 90 degrees and is slowly externally rotated. Thumb pressure is applied by the physician to push the humeral head into place, followed by adduction and internal rotation of the shoulder as the extremity is placed across the chest. There is a higher incidence of iatrogenic fracture.
Following reduction, acute anterior dislocations are treated with sling immobilization. Total time in sling is controversial but may be up to 4 weeks, after which an aggressive program of rehabilitation for rotator cuff strengthening is instituted. Posterior dislocations are treated for 4 weeks in a commercial splint or shoulder spica cast with the shoulder in neutral rotation, followed by physical therapy.
Recurrent dislocation or associated glenoid rim avulsion fractures (bony Bankart lesion) may necessitate operative management, including reduction and internal fixation of the anterior glenoid margin, repair of a Bankart lesion (anterior labral tear), capsular shift, or capsulorrhaphy. Postoperatively, the child is placed in sling immobilization for 4 to 6 weeks with gradual increases in range-of-motion and strengthening exercises.
Atraumatic dislocations rarely require reduction maneuvers as spontaneous reduction is the rule. Only after an aggressive, supervised rehabilitation program for rotator cuff and deltoid strengthening has been completed should surgical intervention be considered. Vigorous rehabilitation may obviate the need for operative intervention in up to 85% of cases.
Psychiatric evaluation may be necessary in the management of voluntary dislocators.
Complications
- Recurrent dislocation: The incidence is 50% to 90%, with decreasing rates of recurrence with increasing patient age (up to 100% in children less than 10 years old). It may necessitate operative intervention, with >90% success rate in preventing future dislocation.
- Shoulder stiffness: Procedures aimed at tightening static and dynamic constraints (subscapularis tendon-shortening, capsular shift, etc.) may result in “overtightening,” resulting in a loss of range of motion, as well as possible subluxation in the opposing direction with subsequent accelerated glenohumeral arthritis.
- Neurologic injury: Neurapraxic injury may occur to nerves in proximity to the glenohumeral articulation, especially the axillary nerve and less commonly the musculocutaneous nerve. These typically resolve with time; a lack of neurologic recovery by 3 months may warrant surgical exploration.
- Vascular injury: Traction injury to the axillary artery has been reported in conjunction with nerve injury to the brachial plexus.
1. Which age group is most affected by pediatric glenohumeral dislocations?
Answer: b) Adolescents. Pediatric glenohumeral dislocations are rare in children, with the majority occurring in adolescents aged 10 to 20 years.
2. What is the most common type of glenohumeral dislocation in children?
Answer: e) Anterior dislocation. Approximately 90% of pediatric glenohumeral dislocations are anterior dislocations.
3. Which mechanism of injury is most commonly associated with anterior shoulder dislocation?
Answer: b) Indirect trauma. Trauma to the upper extremity with the shoulder in abduction, extension, and external rotation is the most common mechanism for anterior shoulder dislocation.
4. What is the recommended treatment for acute anterior dislocations?
Answer: c) Sling immobilization. Acute anterior dislocations are typically treated with sling immobilization. After 4 weeks, rehabilitation for rotator cuff strengthening is initiated.
5. What is the primary complication associated with pediatric glenohumeral dislocations?
Answer: a) Recurrent dislocation. The incidence of recurrent dislocation is high in pediatric glenohumeral dislocations, ranging from 50% to 90%. Surgical intervention may be necessary to prevent future dislocations.