42.3 Joint Dislocation Management: Nursemaid's Elbow & Shoulder Subluxation

Radial Head Subluxation ("Nursemaid's Elbow")

Radial head subluxation—colloquially known as "nursemaid's elbow" or "pulled elbow"—is the most frequent upper extremity injury presenting in toddlers and preschool-aged children. Peak incidence occurs between 1 and 4 years of age, with a slight predilection for females and the left arm (typically the arm held by an adult holding the child's hand).

                  NURSEMAID'S ELBOW PATHOANATOMY

     1. Longitudinal Axial Traction on Extended & Pronated Arm
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     2. Small, Cartilaginous Radial Head Slips Distally Beneath Annular Ligament
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     3. Annular Ligament Slips Over Radial Head into Radiohumeral Joint
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     4. Ligament Becomes Entrapped Between Radial Head & Capitellum
        ──► Toddler holds arm flexed & pronated; refuses movement

Pathophysiology

In children under 5 years of age, the annular ligament is relatively thin, pliable, and loosely attached to the radial neck. Furthermore, the pediatric radial head is predominantly cartilaginous, pliable, and lacks the prominent osseous flare of the mature adult radial head. When sudden longitudinal axial traction is applied to an extended and pronated forearm (e.g., an adult pulling a toddler by the hand to prevent a stumble, lifting a child onto a curb, or swinging a child playfully by the wrists), the radial head is pulled distally beneath the annular ligament. As traction is released, the proximal margin of the annular ligament curls over the radial head and becomes entrapped within the radiohumeral joint space, wedged between the radial head and the humeral capitellum.

Clinical Presentation & When to Avoid Radiographs

• Classic Presentation: The child cries immediately following the traction event, but rapidly settles into a quiet, protective state. The child presents holding the injured extremity splinted closely against the abdomen or lap, with the elbow held in slight flexion (20° to 30°) and pronation. The child adamantly refuses to move or use the arm—a presentation termed "pseudoparalysis".
• Physical Examination Findings: There is a striking absence of inflammatory or traumatic signs: NO localized edema, NO ecchymosis, NO warmth, and NO visible deformity. Palpation of the clavicle, acromion, humerus, olecranon, forearm, and wrist elicits no distress. Minimal, mild discomfort may be localized over the anterolateral radial head. Forearm supination is resisted.
• Radiographic Indications: Radiographs are completely normal in nursemaid's elbow because the displaced annular ligament is radiolucent. Plain radiographs are NOT required in classic presentations!
  • Radiographs are indicated ONLY when: (1) The mechanism of injury involves significant direct blunt trauma, a fall from a height, or suspected non-accidental trauma/abuse; (2) Focal bony point tenderness, significant edema, or deformity is identified on exam; or (3) The child fails to resume normal active arm use after 2 to 3 technically successful reduction attempts.

Closed Reduction Techniques: Hyperpronation vs. Supination-Flexion

Closed reduction is performed immediately at the bedside without sedation or analgesia:

                    NURSEMAID'S REDUCTION MANEUVERS

      HYPERPRONATION TECHNIQUE              SUPINATION-FLEXION TECHNIQUE
   (Higher 1st-Attempt Success: 85-95%)      (Traditional Technique: 70-75%)
  ─────────────────────────────────────     ─────────────────────────────────
  1. Examiner thumb over radial head        1. Examiner thumb over radial head
  2. Support flexed elbow at 90°            2. Apply slight axial traction
  3. Firmly HYPERPRONATE forearm            3. Fully SUPINATE forearm
  4. Palpable "click" felt at radial head   4. Fully FLEX elbow toward shoulder
  5. Child reaches for toy in 10-15 min     5. Palpable "click" felt at radial head

1. The Hyperpronation Technique:
   • Method: The clinician supports the child's elbow at 90° of flexion with one hand, placing the examiner's thumb directly over the anterolateral radial head. With the other hand, grasp the child's distal forearm and wrist, apply slight axial compression, and firmly and smoothly hyperpronate the forearm (rotating the palm downward past full pronation).
   • Endpoint: A subtle but distinct palpable "click" or snap is felt under the examiner's thumb as the annular ligament slides out of the radiohumeral joint back into anatomical position.
   • Evidence: Multiple high-quality randomized controlled trials demonstrate that the hyperpronation technique achieves a significantly higher first-attempt reduction rate (85% to 95%) compared to supination-flexion (70% to 75%), while producing less distress in the child.
2. The Supination-Flexion Technique:
   • Method: Support the elbow with the thumb over the radial head. Apply slight longitudinal traction, fully supinate the forearm (palm facing upward), and then smoothly and fully flex the elbow bringing the child's hand toward the ipsilateral shoulder.
   • Endpoint: Palpable click felt over the radial head during terminal flexion.

Clinical Endpoint & Anticipatory Guidance

• Children typically cry briefly during reduction. Do not expect instantaneous arm usage.
• Clinical Confirmation Protocol: Leave the child quietly in the parent's lap for 10 to 15 minutes. Then, present a desirable stimulus (a colorful toy, sticker, or snack) held above eye level. Successful reduction is confirmed when the child spontaneously and freely reaches overhead with the affected arm using full elbow flexion and supination.
• Disposition: No immobilization, sling, cast, or post-reduction radiograph is needed. Educate caregivers that recurrence occurs in 20% to 30% of children prior to age 5; advise all family members to avoid lifting, pulling, or swinging the child by the hands or wrists.

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Shoulder (Glenohumeral) Dislocation: Anatomy & Epidemiology

The glenohumeral joint is the most frequently dislocated major diarthrodial joint in the human body, accounting for over 50% of all major joint dislocations. The shallow glenoid fossa articulates with less than one-third of the large spherical humeral head at any given moment, sacrificing intrinsic osseous constraint for multi-axial range of motion.

• Classification by Direction:
  • Anterior Dislocation: >95% to 97% of all glenohumeral dislocations.
  • Posterior Dislocation: 2% to 4% of dislocations (frequently missed on initial presentation!).
  • Inferior Dislocation (Luxatio Erecta): <1% (arm locked in hyperabduction overhead).

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Anterior Glenohumeral Dislocation

Mechanism of Injury & Clinical Presentation

• Mechanism: Indirect traumatic force combining abduction, external rotation, and extension (e.g., an athlete's arm tackled while attempting a pass, a volleyball block, or a fall backward onto an outstretched hand).
• Physical Inspection: The patient presents in severe distress, supporting the injured arm in slight abduction and external rotation using the contralateral uninjured hand.
• The "Squared-Off" Shoulder: The lateral rounded contour of the shoulder formed by the deltoid muscle is completely lost. The prominent lateral edge of the acromion creates a sharp, right-angled "squared-off" shoulder deformity with a hollow subacromial depression.
• Palpable Fullness: The dislocated humeral head is readily palpable anteriorly in the subcoracoid or anterior axillary region.
• Dugas Sign: The patient is physically unable to place the hand of the injured arm onto the opposite shoulder while keeping the elbow flat against the chest wall.

Mandatory Neurovascular Evaluation: The Axillary Nerve

[!IMPORTANT] MANDATORY PRE- AND POST-REDUCTION NEUROVASCULAR CHECK

• The Axillary Nerve (C5-C6) winds around the surgical neck of the humerus within the quadrangular space, lying immediately adjacent to the inferior glenohumeral capsule. It is injured in 10% to 20% of anterior shoulder dislocations (primarily neuropraxia from traction/compression).
• Sensory Testing: Test light touch and pinprick sensation over the lateral aspect of the proximal arm—the "deltoid patch" or "regimental badge area".
• Motor Testing: Palpate for isometric contraction of the anterior and lateral deltoid muscle (instruct the patient to attempt gentle abduction against resistance, pain permitting).
• Documentation Requirement: Sensation over the regimental badge area and distal radial pulses MUST be documented in the medical record BEFORE and immediately AFTER closed reduction.

                 AXILLARY NERVE CLINICAL ASSESSMENT

         Deltoid Patch / Regimental Badge Area
         (Lateral Aspect of Proximal Deltoid)
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         ┌───────────────────────────────┐
         │  SENSATION: Light touch &     │
         │  pinprick over deltoid patch  │
         ├───────────────────────────────┤
         │  MOTOR: Isometric deltoid     │
         │  muscle contraction           │
         ├───────────────────────────────┤
         │  PULSE: Radial & ulnar artery │
         │  bounding pulses (<2 sec CRT) │
         └───────────────────────────────┘

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Posterior Glenohumeral Dislocation

Posterior shoulder dislocations represent only 2% to 4% of shoulder dislocations, yet over 50% of posterior dislocations are missed on initial presentation in emergency and primary care clinics, leading to chronic locked dislocations and permanent functional impairment.

The Classic Etiological Triad

Posterior dislocation occurs when the powerful internal rotators (latissimus dorsi, subscapularis, pectoralis major) overpower the relatively weaker external rotators (infraspinatus, teres minor), forcefully driving the humeral head posteriorly out of the glenoid fossa. This is classically triggered by:

1. Generalized Tonic-Clonic Epileptic Seizures;
2. High-Voltage Electrical Shocks / Electrocution;
3. Lightning Strikes. (Less commonly, severe direct frontal trauma to the adducted shoulder).

Clinical Presentation & Radiographic Hallmarks

• Clinical Presentation: The injured arm is held tightly locked in fixed adduction and internal rotation. The patient has an absolute inability to externally rotate the shoulder past neutral! Inspection reveals anterior shoulder flattening, a prominent coracoid process, and a palpable posterior fullness beneath the acromion.
• The Radiographic Trap on AP View: On standard anteroposterior radiographs, posterior dislocations appear deceptively normal because the humeral head remains centered in the vertical plane. Critical AP clues include:
  • The "Lightbulb Sign": Fixed internal rotation projects the spherical humeral head symmetrically without the normal lateral projection of the greater tuberosity, resembling a rounded lightbulb.
  • The "Trough Line" (Reverse Hill-Sachs): A vertical dense impaction line on the anteromedial humeral head where it impacts the posterior glenoid rim.
  • Widened Glenohumeral Joint Space ("Rim Sign"): Distance >6 mm between the anterior glenoid rim and the humeral articular cortex.
• MANDATORY DIAGNOSTIC VIEWS: A standard AP radiograph alone is completely insufficient! An Axillary Lateral View or Scapular Y (Outlet) View is mandatory; the axillary view is 100% definitive, clearly demonstrating the humeral head displaced posteriorly relative to the glenoid fossa.

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Diagnostic Radiographic Series for Shoulder Dislocations

Prior to performing closed reduction, a dedicated 3-view shoulder radiographic series must be obtained to confirm the direction of dislocation and exclude displaced surgical neck fractures (which carry a high risk of iatrogenic head displacement or avascular necrosis during closed reduction attempts):

1. True Anteroposterior (Grashey) View;
2. Scapular Y (Outlet) View;
3. Axillary Lateral View (or Velpeau Axillary View if the arm cannot be abducted).

• Following reduction, a repeat complete 3-view series is mandatory to verify concentric reduction and evaluate for associated osseous fractures.

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Closed Reduction Techniques for Anterior Dislocation

Adequate muscle relaxation and analgesia are essential. Intra-articular Lidocaine Injection (20 mL of 1% plain lidocaine injected into the glenohumeral space 2 cm inferior and lateral to the posterior acromion under sterile technique) provides analgesia equal to intravenous procedural sedation, with lower costs, shorter clinic times, and zero risk of opioid/sedative-induced respiratory depression.

                  CLOSED REDUCTION TECHNIQUES COMPARISON

   Technique       Mechanism & Patient Position      Clinical Advantages
   ─────────────────────────────────────────────────────────────────────────────
   Milch           Supine; gradual overhead          Gentle, atraumatic;
                   abduction + external rotation;    >90% success rate;
                   gentle anterior pressure on head  minimal patient pain

   Cunningham      Seated upright; arm at side;      No traction; relies on
                   massage trapezius, deltoid, &     muscle relaxation;
                   biceps while patient relaxes      superb in elderly

   Scapular        Prone (hanging arm) or seated;    Rotates glenoid into
   Manipulation    push inferior angle of scapula    humeral head; >85% success;
                   medially toward spine             low force required

   Hennepin        Seated or supine; elbow 90°;      Slow millimeter rotation;
   (Ext Rotation)  slowly externally rotate arm      low complication rate;
                   to 70°-80°; spontaneous slip      gentle & controlled
   ─────────────────────────────────────────────────────────────────────────────

1. The Milch Technique:
   • Method: Patient supine. The clinician gently and progressively abducts and externally rotates the arm into the overhead position over 5 to 10 minutes. Once fully abducted overhead, gentle longitudinal axial traction is applied while the clinician uses fingers in the axilla to push the humeral head superiorly and anteriorly over the glenoid rim.
   • Advantages: Highly successful (>90%), gentle, and well-tolerated.
2. The Cunningham Technique (Massage / Relaxation):
   • Method: The patient sits upright in a chair with the arm adducted at the side and elbow flexed to 90°. The examiner kneels and places the patient's hand on the examiner's shoulder. The clinician systematically massages the trapezius, deltoid, and biceps brachii muscles to abolish spasm while instructing the patient to relax the shoulders downward and backward. Within several minutes of relaxation, the humeral head slips effortlessly back into the glenoid without traction.
3. Scapular Manipulation:
   • Method: Patient prone with the injured arm hanging dependent over the edge of the examination table (with 5 to 10 lbs of hanging weights), or seated upright. The clinician stabilizes the superior aspect of the scapula with one hand and uses the other hand to push the inferior angle of the scapula medially toward the vertebral column.
   • Mechanism: Rotates the glenoid fossa to realign with the dislocated humeral head.
4. The Hennepin (External Rotation) Technique:
   • Method: Patient supine or seated with the elbow flexed to 90° against the torso. The clinician gently and slowly externally rotates the forearm millimeter by millimeter over several minutes. When external rotation reaches 70° to 85°, reduction typically occurs spontaneously without any traction.

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Associated Lesions & Age-Dependent Recurrence Risk

Traumatic glenohumeral dislocation disrupts stabilizing osseous and soft-tissue constraints, producing characteristic structural lesions:

• Bankart Lesion: Detachment or avulsion of the anteroinferior glenoid labrum from the underlying fibrous glenoid rim, present in >85% to 90% of traumatic anterior dislocations. A "Bony Bankart" involves an avulsion fracture of the anterior glenoid rim; bone loss >20% to 25% requires surgical reconstruction (Latarjet coracoid transfer).
• Hill-Sachs Lesion: A posterolateral humeral head compression fracture resulting from forceful impaction against the hard anterior glenoid rim during dislocation. Present in up to 80% of anterior dislocations and nearly 100% of recurrent cases.
• Rotator Cuff Tears: Highly prevalent in older patients! While rare in patients <30 years (<5%), full-thickness rotator cuff tears occur in 30% to 60% of patients >40 years and >80% of patients >60 years following an acute dislocation. Any patient >40 years who exhibits persistent weakness in abduction or external rotation following reduction must undergo non-contrast MRI to evaluate for acute rotator cuff disruption.

Recurrence Stratification by Patient Age

The single most critical predictor of recurrent shoulder dislocation is patient age at initial injury:

Post-Reduction Management & Rehabilitation Protocol

• Immobilization: Standard sling immobilization for 1 to 2 weeks solely for pain control. Prolonged immobilization (>2 weeks) is strongly discouraged because randomized trials show it does NOT decrease recurrence rates and promotes joint capsule stiffness and muscular atrophy.
• Rehabilitation: Initiate early protected isometric periscapular and rotator cuff strengthening exercises at 1 to 2 weeks, progressing to active-assisted range of motion. Restrict combined abduction and external rotation for at least 6 weeks.