High Yield Overview
Trauma Imaging: Systematic Approach
Imaging in Acute Orthopaedic Trauma
CTPolytrauma Gold Standard
2 ViewsMinimum for Any Bone
Joint Above/BelowInclude in Images
ATLSPrimary Survey First
Trauma Imaging Hierarchy
CXR + Pelvis XR
PatternATLS primary survey adjuncts
TreatmentLife-threatening injuries first
CT Head/C-spine/Chest/Abdomen/Pelvis
PatternPan-scan for polytrauma
TreatmentComprehensive injury assessment
Extremity X-rays
PatternAfter stabilization
Treatment2 views minimum, include joints
MRI
PatternSelected indications
TreatmentLigaments, cord, occult fractures
Critical Must-Knows
- Two views minimum: At 90° to each other. One view is never enough for fracture assessment.
- Joint above and below: Always include adjacent joints in long bone imaging.
- CT for polytrauma: Pan-scan (C-spine through pelvis) is standard for major trauma.
- Never clear C-spine on X-ray alone: CT is required for obtunded patients.
- Systematic approach: ABCS for every image - Alignment, Bone, Cartilage, Soft tissue.
Examiner's Pearls
- "Satisfaction of search: Finding one injury doesn't mean there aren't more. Complete your systematic review.
- "10% of spinal fractures have a second non-contiguous spinal injury.
- "Pelvic ring injuries require two breaks - always look for the second injury.
- "CT reconstructions (sagittal, coronal, 3D) are essential - axial slices alone are insufficient.
- "Occult fractures: If X-ray negative but clinical concern high, CT or MRI is indicated.
Never Accept One View
A single radiographic view is NEVER adequate for fracture assessment. Fractures can be invisible on one projection but obvious on another. Always obtain a minimum of two views at 90 degrees to each other. This is a fundamental principle that saves missed injuries.
ATLS Imaging Principles
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Primary Survey Imaging
CXR and Pelvis X-ray
CT Trauma Series (Pan-scan)
Extremity Imaging
When to Image
Imaging Decision in Trauma
Hemodynamically unstable patient:
- Resuscitation takes priority
- CXR and pelvis X-ray as adjuncts
- May go directly to OR or IR
- CT only if will not delay definitive treatment
Hemodynamically stable patient:
- CT pan-scan indicated for significant mechanism
- Complete secondary survey imaging
- Time for detailed fracture assessment
Plain Radiograph Principles
Fundamental Rules
Mnemonic
2-2-1Rules of Trauma Radiography
2
Two Views Minimum
At 90° to each other - one view is never enough
2
Two Joints
Include joint above and below for long bones
1
One Systematic Approach
ABCS for every image without exception
Memory Hook:2 views, 2 joints, 1 system
Why Two Views
Fractures Occult on Single Views
| Fracture | View That May Miss It | View That Shows It |
|---|---|---|
| Lateral humeral condyle (pediatric) | AP | Lateral |
| Posterior elbow dislocation | AP | Lateral |
| Scaphoid waist | PA | Scaphoid view |
| Posterior hip dislocation | AP | Lateral |
| Proximal fibula fracture | AP ankle | Full-length tibia/fibula |
ABCS Systematic Approach
Alignment
- Joint congruity
- Bone axis/angulation
- Subluxation/dislocation
- Rotational deformity
Bone
- Cortical breaks (all cortices)
- Trabecular disruption
- Bone density
- Periosteal reaction
Cartilage/Joint
- Joint space width
- Subchondral bone
- Intra-articular fragments
- Effusion
Soft Tissue
- Swelling (localization)
- Fat pads (effusion signs)
- Foreign bodies
- Gas (open fracture)
CT in Trauma
CT Trauma Protocol
Pan-scan Indications
Consider CT pan-scan for:
- High-energy mechanism (MVA greater than 60 km/h, ejection, rollover)
- Fall greater than 3 meters
- Pedestrian vs vehicle
- Motorcycle accident
- GCS less than 15
- Multiple injuries apparent
- Hemodynamically abnormal (or recently unstable)
- Polytrauma
Standard protocol: Non-contrast head → C-spine through pelvis with IV contrast
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CT Advantages
CT vs X-ray in Trauma
| Feature | Plain X-ray | CT |
|---|---|---|
| C-spine fracture detection | 50-60% | Greater than 99% |
| Pelvic fracture detail | Limited | Excellent |
| Solid organ injury | Cannot assess | Gold standard |
| Speed | Faster per image | Faster comprehensive assessment |
| Radiation | Lower per image | Higher total |
| 3D reconstruction | Not possible | Excellent for planning |
Essential CT Reconstructions
Don't Just Look at Axial Slices
Essential reconstructions:
- Sagittal: Spine alignment, vertebral body height
- Coronal: Pelvic ring, acetabular columns, alignment
- 3D Surface: Complex fracture visualization, surgical planning
Bone and soft tissue windows: Review both for all trauma CT
Common error: Reviewing only axial images and missing fractures obvious on reconstructions
Regional Trauma Imaging
Cervical Spine
C-spine Clearance Protocol
Clinical clearance (NEXUS/Canadian C-spine Rules):
- Alert, no midline tenderness, no distracting injury, no intoxication, no neuro deficit
- If criteria met: No imaging needed
If imaging required:
- CT is gold standard (NOT plain films)
- Plain films miss up to 50% of fractures
- MRI if: Neurological deficit, ligamentous injury suspected, obtunded patient with normal CT
Never clear an obtunded patient on plain films alone
Pelvic Ring
Pelvic Ring Imaging
AP pelvis X-ray:
- ATLS adjunct in primary survey
- Assess ring integrity, pubic symphysis, SI joints
CT pelvis:
- Essential for all pelvic ring injuries
- Young-Burgess classification
- Acetabular involvement
- Posterior ring assessment
Remember: Ring breaks in two places - find both injuries
Long Bone Fractures
Long Bone Imaging Principles
| Principle | Application | Why |
|---|---|---|
| Two views at 90° | AP and lateral minimum | Fractures hide on single view |
| Include joints | Above and below | Associated injuries, classify fracture |
| Assess rotation | Compare to normal side | Rotational malunion prevention |
| Consider CT | Intra-articular extension | Surgical planning |
Imaging Pitfalls
Common Missed Injuries
Mnemonic
SCALPCommonly Missed Fractures
S
Scaphoid
Initial X-ray negative in 15-20%. Repeat X-ray, MRI, or CT if clinical suspicion.
C
C-spine (upper)
C1-C2 often missed on plain films. CT is mandatory.
A
Ankle (posterior malleolus)
Subtle on mortise view. Assess on lateral.
L
Lisfranc
Requires weight-bearing views. High index of suspicion.
P
Pelvis (second break)
Ring breaks twice. Find both injuries.
Memory Hook:Don't let injuries SCALP you
Satisfaction of Search
Avoid Premature Closure
Definition: Stopping the search after finding one injury
Prevention:
- Complete ABCS for every image even after finding a fracture
- Actively look for associated injuries
- Remember patterns (ACL tear → check meniscus; pelvic ring → find second break)
- Don't anchor on the obvious injury
Example: Finding a displaced distal radius fracture but missing the associated ulnar styloid avulsion or DRUJ disruption
Adequacy Checklist
Before Calling an Image 'Normal'
Ask yourself:
- Are there two views at 90 degrees?
- Are the joints above and below included?
- Is the image quality adequate (penetration, rotation, coverage)?
- Have I completed ABCS systematically?
- Have I looked at all cortices?
- Does the clinical picture match my interpretation?
- If X-rays are normal but clinical concern persists, have I considered CT/MRI?
If any answer is 'no': Obtain additional imaging or review with senior
Special Situations
Open Fractures
Imaging Considerations in Open Fractures
Foreign body assessment:
- X-ray: Radiopaque foreign bodies (metal, glass)
- May miss wood, plastic, cloth
- CT if X-ray negative but contamination suspected
Gas in soft tissues:
- May indicate open fracture even if wound appears small
- Consider gas gangrene if delayed presentation
Antibiotic administration: Should not be delayed for imaging beyond initial X-rays
Polytrauma Patient
Imaging the Polytrauma Patient
Priorities:
- Life over limb - ATLS approach
- CXR and pelvis X-ray with primary survey
- CT pan-scan when stable
- Extremity X-rays during secondary survey
Temporary measures:
- Splint fractures before moving for CT
- Document neurovascular status before and after
- Photograph open wounds
Communication: Clear handover of imaging findings to receiving team
Pediatric Considerations
Pediatric Trauma Imaging
Different considerations:
- Growth plates (Salter-Harris)
- Plastic deformation (bowing)
- Greenstick fractures
- Higher radiation sensitivity
Comparison views: May be helpful in children (ossification centers vary)
NAI (Non-accidental injury):
- Consider when injury doesn't match history
- Full skeletal survey if suspected
- Dating fractures (callus, healing stage)
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
VIVA SCENARIOStandard
Trauma Imaging Principles
EXAMINER
"A patient presents after an MVA with left thigh pain. The AP X-ray shows no obvious fracture. Is this adequate imaging?"
EXCEPTIONAL ANSWER
No, a single AP X-ray of the femur is not adequate imaging. The fundamental rule in trauma radiography is minimum two views at 90 degrees to each other. A fracture can be invisible on one projection but obvious on another - for example, an undisplaced fracture line running parallel to the X-ray beam may not be visible. I would obtain a lateral view of the femur. Additionally, I need to include the joint above (hip) and joint below (knee) as associated injuries are common and the fracture location relative to the joints affects classification and treatment. Even if both views appear normal, if clinical suspicion remains high - such as significant tenderness, inability to weight-bear, or substantial mechanism - I would consider CT to exclude an occult fracture. I would also complete my ABCS systematic review on all images: checking alignment, all bony cortices, cartilage/joint spaces, and soft tissues for swelling that might localize injury.
KEY POINTS TO SCORE
Two views minimum at 90 degrees
Include joint above and below
Complete ABCS systematic review
CT if clinical suspicion persists despite normal X-rays
COMMON TRAPS
✗Accepting one view as adequate
✗Not including adjacent joints
✗Dismissing injury based on negative X-ray with high clinical suspicion
LIKELY FOLLOW-UPS
"What fractures are commonly missed on initial X-rays?"
"When would you order a CT for a femoral shaft fracture?"
"What is satisfaction of search?"
VIVA SCENARIOStandard
Polytrauma Imaging
EXAMINER
"A 35-year-old pedestrian struck by a car at 50km/h arrives with GCS 13. Describe your imaging approach."
EXCEPTIONAL ANSWER
This is a polytrauma patient with significant mechanism and altered consciousness, requiring systematic ATLS-based imaging. In the primary survey, I would obtain a chest X-ray and AP pelvis X-ray as adjuncts - these can identify immediately life-threatening injuries like tension pneumothorax or unstable pelvic ring injury requiring intervention. Once the patient is hemodynamically stable enough for the CT scanner, I would obtain a CT trauma pan-scan: non-contrast CT head to assess for intracranial injury explaining the reduced GCS, then CT of C-spine through pelvis with IV contrast. CT C-spine is essential - I cannot clear the cervical spine clinically in this patient, and plain films miss 50% of cervical fractures. The contrast phase helps assess for solid organ injury and vascular damage. After CT and during the secondary survey, I would obtain X-rays of any clinically concerning extremities - two views each, including joints above and below. I would systematically review all imaging using ABCS, being vigilant about satisfaction of search and looking for associated injuries.
KEY POINTS TO SCORE
ATLS approach: CXR and pelvis X-ray in primary survey
CT pan-scan when hemodynamically stable
Cannot clear C-spine clinically - CT required
Extremity X-rays in secondary survey
COMMON TRAPS
✗Delaying resuscitation for imaging
✗Trying to clear C-spine clinically in GCS less than 15
✗Forgetting secondary survey imaging
LIKELY FOLLOW-UPS
"What mechanism would not require CT pan-scan?"
"How do you clear C-spine in an obtunded patient?"
"What is the radiation dose of a trauma CT?"
VIVA SCENARIOStandard
Missed Injuries
EXAMINER
"What are commonly missed orthopaedic injuries and how do you avoid missing them?"
EXCEPTIONAL ANSWER
Commonly missed orthopaedic injuries can be remembered with the mnemonic SCALP: Scaphoid fractures (negative X-ray in 15-20%, need repeat imaging or MRI/CT if clinical suspicion); Cervical spine injuries especially upper C-spine (plain films miss up to 50%, CT is mandatory); Ankle posterior malleolus and syndesmotic injuries (subtle on mortise, need lateral view); Lisfranc injuries (require weight-bearing views, easily missed non-WB); and Pelvic ring second break (ring breaks twice, must find both). To avoid missing injuries, I employ several strategies: First, always obtain minimum two views at 90 degrees. Second, complete my ABCS systematic review for every image, even after finding an obvious injury - this prevents satisfaction of search where you stop looking after finding one problem. Third, know injury patterns and actively look for associated injuries. Fourth, if X-rays are normal but clinical suspicion is high, escalate to CT or MRI rather than discharge. Fifth, maintain a low threshold for repeat imaging or advanced imaging in high-risk situations.
KEY POINTS TO SCORE
SCALP: Scaphoid, C-spine, Ankle, Lisfranc, Pelvis
Complete ABCS even after finding an injury
Know injury patterns - look for associated injuries
Escalate imaging if clinical concern persists
COMMON TRAPS
✗Accepting normal X-rays despite high clinical suspicion
✗Stopping search after finding one injury
✗Not knowing common missed injury patterns
LIKELY FOLLOW-UPS
"What is the imaging for suspected scaphoid fracture?"
"What injuries are associated with ACL tears?"
"How do you identify a Lisfranc injury?"
Trauma Imaging Exam Day Cheat Sheet
High-Yield Exam Summary
Fundamental Rules
- •TWO views minimum at 90°
- •Include joint ABOVE and BELOW
- •Complete ABCS for every image
- •Don't stop after finding one injury
ATLS Imaging
- •Primary survey: CXR + Pelvis X-ray
- •CT pan-scan when stable
- •Never clear C-spine on X-ray alone
- •CT required for GCS less than 15
Commonly Missed (SCALP)
- •Scaphoid: MRI/CT if X-ray negative
- •C-spine: CT mandatory, not X-ray
- •Ankle: Posterior malleolus, syndesmosis
- •Lisfranc: Weight-bearing views essential
- •Pelvis: Ring breaks twice - find both
CT Essentials
- •Review sagittal AND coronal reconstructions
- •3D for complex fractures
- •Bone AND soft tissue windows
- •CT C-spine sensitivity greater than 99% vs 50% for X-ray