Imaging Modalities & Basics - Tools of Trade
- X-ray (Radiography):
- First-line for suspected fractures/dislocations.
- Requires 2+ orthogonal views (e.g., AP, Lateral); special views (scaphoid, mortise) if needed.
- Pros: Widely available, quick, inexpensive. Cons: Poor soft tissue detail, ionizing radiation.
- CT (Computed Tomography):
- Indications: Complex/occult fractures (articular involvement), pre-operative planning, spinal trauma.
- Pros: Excellent bone detail, multiplanar reconstruction. Cons: Higher radiation dose, more expensive.
- MRI (Magnetic Resonance Imaging):
- Indications: Soft tissue injuries (ligaments, tendons, menisci, cartilage), occult fractures (bone marrow edema), spinal cord injury, osteomyelitis, AVN.
- Pros: Superior soft tissue contrast, no ionizing radiation. Cons: Expensive, time-consuming, contraindications.
- US (Ultrasonography):
- Indications: Superficial soft tissue injuries (tendons, muscles), joint effusions, foreign bodies, pediatric fractures (cartilage), dynamic assessment.
- Pros: Real-time, dynamic, no radiation, portable. Cons: Operator-dependent, limited deep penetration.
⭐ Initial imaging for suspected fracture is X-ray (at least 2 orthogonal views).
Appendicular Skeleton Trauma - Limbs in Distress
Rapid identification of fracture patterns and dislocations is crucial. Common injuries include:
| Injury Type | Key X-ray Signs / Eponyms / Notes |
|---|---|
| Upper Limb | |
| Shoulder Dislocation | Anterior (>95%): Subcoracoid. Bankart, Hill-Sachs lesions. Posterior (rare): "Lightbulb" sign, trough line. Axillary view essential. |
| Colles' Fracture | Distal radius, dorsal displacement & angulation. "Dinner fork" deformity. FOOSH. |
| Smith's Fracture | Distal radius, volar displacement & angulation. "Garden spade" deformity. Reverse Colles'. |
| Monteggia Fracture | Proximal ulna fracture + anterior dislocation of radial head. |
| Galeazzi Fracture | Distal third radial shaft fracture + dislocation of distal radioulnar joint (DRUJ). |
| Lower Limb | |
| Hip Fracture | Intracapsular (subcapital, transcervical): Garden classification I-IV. High risk of AVN. Extracapsular (intertrochanteric, subtrochanteric). |
| Ankle Fracture (Weber) | Relates to fibula # level reference to syndesmosis. A: Below. B: At level. C: Above. Stability decreases A→C. |
📌 Mnemonic (GRIMUS): Galeazzi - Radius #, Inferior (Distal) RUJ dislocation; Monteggia - Ulna #, Superior (Proximal) Radial head dislocation.
Axial & Special Cases - Core & Unique Injuries
-
Physeal Injuries (Salter-Harris Classification):
- 📌 SALTER Mnemonic:
- I: Slipped (through physis)
- II: Above (physis + metaphysis)
- III: Lower (physis + epiphysis, intra-articular)
- IV: Through (metaphysis + physis + epiphysis, intra-articular)
- V: ERasure/Rammed (crush of physis)
⭐ Salter-Harris Type II is the most common physeal fracture, involving fracture through the physis and metaphysis.
- 📌 SALTER Mnemonic:
-
Pelvic Ring Injuries: Stability is paramount.
- Young-Burgess: APC, LC, VS, CM. Tile: A (Stable), B (Rotationally Unstable), C (Vertically & Rotationally Unstable).
- Initial Stability Assessment:
- Spinal Trauma:
- Unstable examples: Jefferson (C1 burst), Hangman's (C2 pedicles), Chance (flexion-distraction).
- Denis 3-column theory: Involvement of ≥2 columns often implies instability.
High‑Yield Points - ⚡ Biggest Takeaways
- X-ray is first-line for suspected fractures/dislocations; obtain two orthogonal views.
- CT excels for complex/occult fractures (scaphoid, femoral neck) and surgical planning.
- MRI is best for soft tissue injuries (ligaments, tendons, menisci) and bone marrow edema.
- Salter-Harris fractures affect pediatric growth plates; accurate classification is vital.
- Positive fat pad signs (e.g., elbow) strongly suggest an occult fracture.
- Ultrasound (MSK) useful for superficial soft tissues, effusions, and dynamic assessment.
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