8.3 Upper Extremity Fractures, Dislocation Management & Peripheral Nerve Injuries

Upper Extremity Fractures, Dislocation Management & Peripheral Nerve Injuries

Clinical Core Principle: Upper extremity injuries directly threaten functional independence and hand dexterity. Because major peripheral nerves (radial, median, ulnar, and axillary) and vital vascular conduits course in intimate proximity to bony cortices and joint capsules, orthopaedic nurses must integrate systematic neurovascular mapping with rapid recognition of reduction emergencies.

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1. Clavicle Fractures: Anatomy, Deforming Forces & Skin Tenting

The clavicle acts as a strut connecting the axial skeleton to the upper extremity. Fractures are classified anatomically (Allman classification):

• Group I (Middle Third / Midshaft): Accounts for ~80% of all clavicle fractures. The midshaft is the thinnest portion of the bone and lacks muscular or ligamentous attachments.
• Group II (Distal / Lateral Third): Accounts for ~15%; involves coracoclavicular (CC) ligament disruption.
• Group III (Proximal / Medial Third): Accounts for ~5%; results from high-energy direct anterior chest impacts.

                     CLAVICLE DEFORMING MUSCLE FORCES
  ┌──────────────────────────────────┬──────────────────────────────────┐
  │ Proximal / Medial Segment        │ Distal / Lateral Segment         │
  ├──────────────────────────────────┼──────────────────────────────────┤
  │ • Sternocleidomastoid (SCM)      │ • Weight of the arm & gravity    │
  │ • Displaced Superiorly & Post.   │ • Pectoralis major & Latissimus  │
  │                                  │ • Displaced Inferiorly & Med.    │
  └──────────────────────────────────┴──────────────────────────────────┘

Critical Complications & Nursing Alerts

1. Impending Open Fracture ("Skin Tenting"): When a sharp, displaced medial or lateral cortical fragment elevates, stretches, and blanches the overlying skin. The cutaneous microcirculation becomes occluded, creating rapid full-thickness skin necrosis that converts a closed fracture into an open, contaminated wound. Nursing Action: Support the arm in a sling to remove downward traction, avoid manipulating the tented area, and immediately alert the orthopaedic surgeon for urgent reduction or operative stabilization.
2. Neurovascular & Pleural Compromise: The subclavian artery, subclavian vein, and cords of the brachial plexus pass directly posterior to the middle third of the clavicle over the first rib. Nurses must assess bilateral radial pulses, capillary refill, and motor/sensory function across the median, ulnar, and radial distributions. Auscultate bilateral breath sounds to rule out apical pneumothorax or hemothorax.
3. Immobilization: Modern clinical trials show that a simple standard arm sling yields equivalent healing rates, lower complication rates, and superior patient comfort compared to rigid figure-of-eight bandages (which frequently cause axillary skin breakdown and brachial plexus compression).

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2. Proximal Humerus Fractures: The Neer Classification

Proximal humerus fractures are common fragility injuries in elderly adults with osteoporosis following ground-level falls onto an outstretched hand (FOOSH), but also occur in young individuals following high-energy trauma.

Codman's Four Anatomic Segments & The Neer Criteria

Charles Neer categorized proximal humerus fractures based on four distinct structural components:

1. Articular surface of the humeral head (anatomic neck)
2. Greater tuberosity (insertion site for supraspinatus, infraspinatus, and teres minor)
3. Lesser tuberosity (insertion site for subscapularis)
4. Humeral shaft (surgical neck)

The Neer Displacement Rule: A segment is clinically defined as a separate "part" ONLY if it is displaced by greater than 1.0 cm of translation or angulated by greater than 45 degrees from its anatomic position. If fracture lines are present without meeting these displacement criteria, the injury is classified as a One-Part (nondisplaced) fracture, regardless of the number of fracture lines.

                    NEER PROXIMAL HUMERUS CLASSIFICATION
  ┌────────────────┬────────────────────────────────────┬────────────────────────────┐
  │ Classification │ Structural Criteria                │ Management Approach        │
  ├────────────────┼────────────────────────────────────┼────────────────────────────┤
  │ One-Part       │ Minimal / No displacement (<1cm)   │ Sling + Early PROM (14d)   │
  │ Two-Part       │ 1 segment displaced (>1cm / >45°)  │ Closed vs. ORIF / Plating  │
  │ Three-Part     │ 2 segments displaced; head intact  │ ORIF (PHILOS Plate)        │
  │ Four-Part      │ All 4 segments displaced; head out │ Arthroplasty (rTSA / Hemi) │
  └────────────────┴────────────────────────────────────┴────────────────────────────┘

Axillary Nerve Assessment

The axillary nerve winds directly around the posterior aspect of the surgical neck of the humerus within the quadrangular space. Fractures of the surgical neck or anterior glenohumeral dislocations frequently cause axillary neuropraxia. The nurse evaluates axillary nerve integrity by:

• Sensory: Testing light touch over the lateral aspect of the upper arm ("regimental badge" or deltoid patch).
• Motor: Palpating for isometric contraction of the deltoid muscle during attempted active shoulder abduction (avoiding active arm movement if the fracture is unreduced).

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3. Humeral Shaft Fractures & Radial Nerve Neuropraxia

Diaphyseal humeral fractures (AO/OTA Type 12) result from direct lateral blows (transverse/bending wedge) or rotational twisting forces (spiral/helical patterns).

                   RADIAL NERVE & THE HOLSTEIN-LEWIS FRACTURE
  ┌─────────────────────────────────────────────────────────────────────────────┐
  │  • Radial nerve wraps around posterior spiral groove of mid-diaphysis       │
  │  • Pierces lateral intermuscular septum in distal third of humerus          │
  │  • Distal-third spiral fracture = Holstein-Lewis Fracture                   │
  │  • Radial nerve entrapped / stretched -> Classic "Wrist Drop"               │
  └─────────────────────────────────────────────────────────────────────────────┘

The Holstein-Lewis Fracture & Radial Nerve Palsy

In the distal third of the humerus, the radial nerve is tethered as it pierces the lateral intermuscular septum to enter the anterior compartment. A spiral fracture of the distal third of the humeral shaft—termed a Holstein-Lewis fracture—carries an exceptionally high rate of radial nerve entrapment or traction injury (~15–20%).

• Clinical Manifestations of Radial Nerve Palsy:
  • Motor Deficit: Inability to actively extend the wrist ("wrist drop"), inability to extend the fingers at the metacarpophalangeal (MCP) joints, and loss of active thumb extension/abduction (extensor pollicis longus/brevis).
  • Sensory Deficit: Paresthesia, numbness, or loss of two-point discrimination over the dorsal surface of the first web space (dorsum between thumb and index finger).
• Conservative Management & Sarmiento Bracing: Over 85% to 90% of closed radial nerve palsies represent a neuropraxia that resolves spontaneously within 3 to 6 months. Closed humeral shaft fractures are initially managed with a coaptation splint, followed at 1 to 2 weeks by transition to a functional Sarmiento brace (circumferential hydrostatic compression of the arm musculature while permitting free active elbow and shoulder motion). Surgical nerve exploration is reserved for open fractures, secondary palsies developing after closed manipulation, or failure to demonstrate electromyographic (EMG) recovery by 4 to 6 months.

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4. Distal Radius Fractures: Colles vs. Smith & Acute Carpal Tunnel Syndrome

Distal radius fractures are the most frequent fractures of the upper extremity, reflecting distinct injury mechanisms and displacement vectors:

Acute Carpal Tunnel Syndrome (Median Nerve Emergency)

The median nerve travels through the rigid fibro-osseous carpal tunnel immediately adjacent to the volar cortical rim of the distal radius. Post-traumatic hematoma, severe fracture displacement, or extreme wrist flexion during splinting elevates carpal tunnel pressure, inducing acute median nerve ischemia.

• Clinical Indicators: Progressive burning pain, numbness, and paresthesia in the volar thumb, index, middle, and radial half of the ring finger, accompanied by progressive weakness of thumb abduction (abductor pollicis brevis / loss of palmar opposition).
• Emergency Nursing Intervention: Immediately loosen or remove constrictive dressings/splints, reposition the wrist into a neutral (slight 10°–15° extension) position (avoiding the historical Cotton-Loder position of extreme flexion and ulnar deviation), and urgently notify the surgeon for emergency bedside closed reduction or open carpal tunnel release.

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5. Scaphoid Fractures & Emergency Joint Dislocations

                  UPPER EXTREMITY NERVE MAPPING AT A GLANCE
  ┌───────────────┬───────────────────────────────┬─────────────────────────────┐
  │ Nerve         │ Motor Testing Action          │ Autonomous Sensory Area     │
  ├───────────────┼───────────────────────────────┼─────────────────────────────┤
  │ Axillary      │ Isometric Deltoid Contraction │ Lateral Deltoid Patch       │
  │ Radial        │ Wrist & MCP Finger Extension  │ 1st Dorsal Web Space        │
  │ Median        │ Thumb Opposition ("OK" sign)  │ Palmar Index Finger Tip     │
  │ Ulnar         │ Finger Abduction (Interossei) │ Palmar Little Finger Tip    │
  │ Musculocut.   │ Biceps Flexion / Supination   │ Lateral Forearm             │
  └───────────────┴───────────────────────────────┴─────────────────────────────┘

Scaphoid (Navicular) Fractures

The scaphoid is the most commonly fractured carpal bone (~70%). It is typically injured during a FOOSH with the wrist loaded in hyperextension and radial deviation.

• Physical Examination: Tenderness upon deep palpation within the anatomical snuffbox (bounded by the extensor pollicis longus tendon medially, and extensor pollicis brevis and abductor pollicis longus tendons laterally), pain with axial compression of the thumb metacarpal, and scaphoid tubercle tenderness.
• Retrograde Blood Supply: The scaphoid receives its primary blood supply from branches of the radial artery entering at the distal pole and coursing retrogradely to supply the proximal pole. Fractures through the proximal third sever this blood supply, resulting in a high incidence of avascular necrosis (AVN) and nonunion (scaphoid nonunion advanced collapse [SNAC]).
• Presumed Fracture Protocol: Initial radiographs may be completely normal in up to 15% to 20% of acute scaphoid fractures. Any patient with clinical snuffbox tenderness following trauma must be placed in a Thumb Spica splint/cast and re-imaged with repeat radiographs or MRI in 10 to 14 days.

Emergency Joint Dislocations

1. Anterior Shoulder (Glenohumeral) Dislocation (~95% of shoulder dislocations):
   • Mechanism: Abduction, extension, and external rotation force.
   • Presentation: Arm held in slight abduction and external rotation; flattening of normal lateral deltoid contour ("squared-off shoulder") with a palpable empty glenoid fossa.
   • Nerve at Risk: Axillary Nerve (assess lateral deltoid sensory patch).
2. Posterior Elbow Dislocation (~90% of elbow dislocations):
   • Mechanism: Severe hyperextension load onto an outstretched hand.
   • Presentation: Olecranon prominent posteriorly, forearm shortened, elbow locked in flexion.
   • Neurovascular Risks: Brachial Artery occlusion/laceration and Median / Ulnar Nerve entrapment. High risk for forearm acute compartment syndrome (Volkmann's ischemic contracture).
3. Posterior Hip Dislocation:
   • Mechanism: High-velocity deceleration impacts ("dashboard injury") where an axial load is transmitted down the femoral shaft with the hip flexed and adducted.
   • Presentation: The injured limb is shortened, internally rotated, and adducted (distinguishing it from a hip fracture, which is externally rotated).
   • The Six-Hour Emergency Rule: Closed or open hip reduction MUST be achieved within 6 hours of injury. Delays beyond 6 hours cause irreversible femoral head avascular necrosis (AVN) due to severe compression of the medial femoral circumflex vessels. Assess the Sciatic Nerve (specifically the peroneal division, testing for foot drop and numbness over the dorsum of the foot).