6.1 Fractures, Dislocations & Orthopedic Trauma

Orthopedic Trauma & Fracture Principles

Evaluation of acute musculoskeletal trauma requires immediate systematic stabilization, precise physical examination, and rapid identification of neurovascular compromise. Every fracture or dislocation examination must include assessment of distal pulses, capillary refill, motor function, and cutaneous sensation before and after reduction.

Upper Extremity Fractures & Dislocations

Clavicle fractures occur primarily from direct falls onto the shoulder. The middle third of the clavicle is fractured in 80% of cases. Examination shows focal tenderness, crepitus, and downward displacement of the distal shoulder girdle. Initial management involves neurovascular examination of the subclavian vessels and brachial plexus, followed by sling immobilization. Operative open reduction and internal fixation (ORIF) is reserved for severe displacement (> 100% overlap), shortening > 2 cm, or neurovascular injury.

Dislocations of the glenohumeral joint present with distinct physical deformities:

• Anterior Shoulder Dislocation: Comprises > 95% of shoulder dislocations. Resulting from forced abduction and external rotation, the humeral head shifts anteriorly, producing flattening of the deltoid contour. The axillary nerve is at highest risk for injury, manifesting as motor weakness during shoulder abduction and sensory loss over the lateral deltoid ("regimental badge area").
• Posterior Shoulder Dislocation: Characteristic of violent muscular contractions secondary to grand mal seizures or high-voltage electrocution. The arm is held locked in adduction and internal rotation. Standard AP plain radiographs may appear falsely normal; an axillary or scapular Y-view X-ray is required to confirm posterior displacement.

Humeral shaft fractures carry a significant risk of radial nerve trauma as the nerve traverses the spiral groove, resulting in wrist drop (loss of wrist/finger extension) and sensory loss over the dorsal first interdigital web space. Supracondylar fractures of the humerus occur in children falling on an outstretched hand (FOOSH). Displaced supracondylar fractures risk injury to the brachial artery and median nerve (anterior interosseous nerve branch). Tight casting or un-recognized neurovascular compromise can precipitate Volkmann ischemic contracture of the forearm flexors.

In distal radius and carpal trauma:

• Scaphoid Fracture: Most common carpal fracture, caused by a FOOSH. Patients present with point tenderness in the anatomical snuffbox. Because blood supply enters retrograde via the radial artery, proximal pole fractures carry a high risk of avascular necrosis (AVN) and nonunion. Plain radiographs immediately after injury miss up to 20% of non-displaced fractures. If initial X-rays are negative but suspicion remains high, immobilize in a thumb spica cast with mandatory repeat plain radiographs in 10 to 14 days, or MRI/CT.
• Colles Fracture: Distal radius fracture with dorsal displacement, producing a "dinner-fork" deformity.
• Boxer's Fracture: Fifth metacarpal neck fracture from punching a closed fist. Angulation > 40 degrees requires closed reduction and ulnar gutter splinting.

Lower Extremity Trauma & Joint Injuries

Hip and pelvic injuries present with distinct limb positions:

• Femoral Neck & Intertrochanteric Fractures: Occur in elderly patients after low-energy falls. The leg is shortened and externally rotated. Femoral neck fractures disrupt the medial circumflex femoral artery, predisposing to avascular necrosis of the femoral head and necessitating hemiarthroplasty.
• Posterior Hip Dislocation: Occurs in motor vehicle accidents when the knee impacts the dashboard. The leg is shortened, adducted, and internally rotated. The sciatic nerve is susceptible to compression, causing foot drop.

Ligamentous and meniscal knee injuries include:

• Anterior Cruciate Ligament (ACL) Tear: Caused by non-contact pivoting. Patients report a loud "pop" followed by rapid intra-articular hemarthrosis within 2 hours. Physical examination reveals positive Lachman test (most sensitive) and anterior drawer test.
• Meniscal Tears: Result from twisting on a planted foot. Characterized by joint line tenderness, delayed effusion, and joint locking. The McMurray test is positive.
• Ottawa Ankle Rules: Plain ankle radiographs are indicated only if there is pain in the malleolar zone AND bone tenderness along the posterior 6 cm or tip of either malleolus, OR an inability to bear weight for 4 steps immediately and in the emergency department.

Orthopedic Emergencies: Compartment Syndrome & Fat Embolism

Acute Compartment Syndrome occurs when increased pressure within a closed fascial compartment compromises tissue perfusion, most commonly after tibial shaft fractures. The earliest and most sensitive indicator is pain out of proportion to physical findings, exacerbated by passive stretch of compartment muscles. Paresthesias, hypesthesia, pallor, and paralysis follow. Absence of distal pulses is a late sign. Diagnosis is confirmed by compartment pressure > 30 mmHg or delta pressure (diastolic BP minus compartment pressure) < 30 mmHg, mandating immediate surgical decompressive fasciotomy.

Fat Embolism Syndrome (FES) arises 24 to 72 hours following closed long-bone (femur, tibia) or pelvic fractures. Microvascular occlusion by neutral fat globules generates a classic triad:

1. Respiratory Distress: Hypoxia, dyspnea, tachypnea, and bilateral alveolar infiltrates (PaO2/FiO2 < 300).
2. Neurological Dysfunction: Acute confusion, agitation, or coma.
3. Petechial Rash: Non-palpable petechiae over the neck, axillae, chest, and conjunctivae (~50% of cases). Management is strictly supportive with high-flow oxygen and mechanical ventilation.

Open Fractures represent surgical emergencies. Immediate treatment requires parenteral antibiotics: IV cefazolin for Gustilo-Anderson Type I/II (< 10 cm wound), adding IV gentamicin for Type III (> 10 cm high-energy wound), and adding IV penicillin G for soil exposure to cover Clostridium perfringens. Formal operative debridement must occur within 24 hours.

Diagnostic Algorithm: Acute Orthopedic Trauma Triage

[ Acute Limb Trauma / Fracture Suspected ]
                   │
       ┌───────────┴───────────┐
       ▼                       ▼
[ Open Fracture ]       [ Closed Fracture ]
       │                       │
       ├─► IV Cefazolin        ├─► Assess Neurovascular Status & Compartment Pressure
       ├─► Add Gentamicin      │
       │   (if Type III)       ├─► Pain with passive stretch? / Pressure > 30 mmHg?
       ├─► Add Penicillin G    │      ├──► YES ──► Immediate Decompressive Fasciotomy
       │   (if soil exposure)  │      └──► NO  ──► Closed Reduction & Splinting
       ▼                       │
[ Operative Debridement ]◄─────┴─► Radiographic Assessment (Ottawa Rules / Snuffbox)

Summary Matrix of Orthopedic Trauma & Nerve Associations