High-yield overview
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.
Clinical 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.
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
Hook:2 views, 2 joints, 1 system
Principles of Trauma Imaging in the ATLS Framework
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
Why Two 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)
Clinical Imaging: 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
CT Advantages
| 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
| 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 |
Systematic Approach: 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.
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)
Differential Diagnosis: Choosing the Right Modality
Modality Selection by Clinical Problem
When initial radiographs are negative but suspicion persists, the choice between CT, MRI and bone scintigraphy depends on the anatomical region, the urgency, radiation considerations and local availability. Picking the wrong second-line test wastes time and may still miss the injury.
| Clinical Problem | First-Line | Best Second-Line | Key Reasoning |
|---|---|---|---|
| Suspected scaphoid fracture | PA, lateral, scaphoid views | MRI (or CT) | MRI sensitivity ~88%, near-perfect specificity; avoids unnecessary casting |
| Occult hip fracture (elderly, can't weight-bear) | AP pelvis + lateral hip | MRI | MRI is gold standard; CT can miss non-displaced femoral neck fractures |
| Cervical spine (high-risk or obtunded) | None - go to CT | CT C-spine | Plain films miss many fractures; CT sensitivity over 99% |
| Spinal cord injury / ligamentous | CT (bone) | MRI | MRI shows cord, disc, ligament and SCIWORA in children |
| Pelvic ring / acetabulum | AP pelvis | CT with reconstructions | Defines posterior ring, columns, planning |
| Stress / insufficiency fracture | AP/lateral region | MRI | Marrow oedema visible before cortical change |
| Solid organ / vascular injury | FAST / CXR | CT angiography | Plain films cannot assess; CTA defines active bleeding |
MRI vs CT vs Bone Scan for the Occult Fracture
For most occult fractures (scaphoid, hip, sacrum, stress fractures), MRI is the most useful single second-line test because it shows marrow oedema before any cortical change and has the best balance of sensitivity and specificity. CT is faster and excellent for cortical/comminuted detail and surgical planning but can miss non-displaced trabecular fractures. Bone scintigraphy is highly sensitive but poorly specific and involves a diagnostic delay - rarely first choice in modern practice.
Evidence Base & Landmark Studies
The modern approach to trauma imaging is built on a small number of large, high-quality decision-rule studies and one landmark randomised trial of pan-scan. Knowing these by name, design and headline number is high-yield for vivas.
Evidence
REACT-2: Immediate Total-Body CT vs Standard Work-Up (RCT)
Sierink JC, Treskes K, Edwards MJR, et al. • Lancet (2016)
Key Findings:
- International multicentre RCT of 1403 severely injured adults randomised to immediate total-body CT versus conventional imaging with selective CT.
- In-hospital mortality was identical (16% vs 16%, p=0.92), with no benefit in the polytrauma or traumatic brain injury subgroups.
Clinical implication: Pan-scan speeds diagnosis but does NOT reduce mortality for all comers; because it increases radiation dose, it should be selectively applied rather than used reflexively in every trauma activation.
Evidence
REACT-2: Cost-Effectiveness of Immediate Total-Body CT
Treskes K, Sierink JC, Edwards MJR, et al. • British Journal of Surgery (2021)
Key Findings:
- Economic analysis of 928 REACT-2 patients: overall hospital costs were similar between the two strategies.
- Immediate total-body CT had a high probability of being cost-effective specifically in multiple trauma (0.8 to 0.9) and traumatic brain injury (over 0.9).
Clinical implication: Reserve immediate pan-scan for patients with clear polytrauma or significant head injury, where it is most likely to be both clinically and economically justified.
Areas of Controversy & Uncertainty
Unresolved Questions in Trauma Imaging
- Pan-scan vs selective CT: REACT-2 showed no mortality benefit overall, yet pan-scan is widely used for speed and completeness. The debate centres on radiation stewardship and patient selection rather than diagnostic accuracy.
- Clearing the C-spine in the obtunded patient with a normal CT: Modern multidetector CT has very high sensitivity, and several groups now clear the collar on CT alone. Others still obtain MRI to exclude purely ligamentous injury. Practice varies and guidelines are not unanimous.
- Radiation in young patients: Cumulative dose from repeated CT (especially in children and young polytrauma survivors) drives an ALARA approach and increasing use of MRI and low-dose CT protocols.
- Whole-body MRI and dual-energy CT: Emerging roles for marrow oedema and bone-bruise detection without ionising radiation, but availability, time and cost limit acute use.
Guidelines, Registries & Global Practice
Global Epidemiology
Trauma is a leading cause of death and disability worldwide, accounting for roughly 4 to 5 million deaths each year, with road-traffic injury the single largest contributor and a disproportionate burden in low- and middle-income countries. Imaging is central to early decision-making, but access to CT and MRI varies enormously between high-resource trauma systems and limited-resource settings.
Side-by-Side Guideline Comparison
| Body | Cervical Spine | Whole-Body CT | Emphasis |
|---|---|---|---|
| ATLS (ACS-COT) | CXR + pelvis as primary-survey adjuncts; CT for clearance | Adjunct once stabilised | ABCDE, life-threatening injuries first |
| NICE (UK, NG39) | Canadian C-Spine Rule to select CT; CT first-line if indicated | Whole-body CT for adults with suspected multiple injuries | Selective imaging, avoid plain C-spine films in adults |
| ACR Appropriateness Criteria (US) | CT for moderate/high risk | Supports CT for major mechanism | Evidence-based modality selection |
| EFAST / WSES (Europe) | CT-led work-up | Pan-scan in haemodynamically stable polytrauma | FAST in unstable patients, CT when stable |
A Key Global Divergence
NICE explicitly advises against plain-film (three-view) cervical-spine series as the primary imaging in adults who need imaging, going straight to CT. This contrasts with older or resource-limited protocols where plain films remain the only available first-line test. Be able to justify CT-first on sensitivity grounds while acknowledging that plain radiography retains a role where CT is unavailable.
Registry & System-Level Evidence
National and regional trauma registries (for example the UK Trauma Audit and Research Network and the US National Trauma Data Bank) consistently link the introduction of in-resuscitation-room or rapid-access CT and standardised pan-scan protocols to shorter times to diagnosis and definitive care. These are observational, system-level signals rather than randomised mortality benefit, consistent with REACT-2.
High- vs Limited-Resource Practice Variation
Adapting the Approach to Available Resources
- High-resource trauma centre: CT in or adjacent to the resuscitation bay, rapid pan-scan for major trauma, MRI readily available for cord and occult fracture, formal radiologist reporting.
- Limited-resource setting: Plain radiography and clinical decision rules (NEXUS, Canadian C-Spine Rule, Ottawa rules) become even more valuable to triage scarce CT; FAST ultrasound substitutes for CT in assessing free fluid; transfer pathways and clear documentation matter most.
- Universal principles: ABCDE first, two views minimum, joint above and below, systematic ABCS review, and never clearing the obtunded C-spine clinically - these hold regardless of available technology.
Clinical Decision Scenarios
Practise clinical reasoning and management decisions out loud
Viva scenarioStandard
Trauma Imaging Principles
Clinical prompt
“A patient presents after an MVA with left thigh pain. The AP X-ray shows no obvious fracture. Is this adequate imaging?”
Practical approach
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 clinical points
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 pitfalls
Accepting one view as adequate
Not including adjacent joints
Dismissing injury based on negative X-ray with high clinical suspicion
Further questions
“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
Clinical prompt
“A 35-year-old pedestrian struck by a car at 50km/h arrives with GCS 13. Describe your imaging approach.”
Practical approach
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 clinical points
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 pitfalls
Delaying resuscitation for imaging
Trying to clear C-spine clinically in GCS less than 15
Forgetting secondary survey imaging
Further questions
“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
Clinical prompt
“What are commonly missed orthopaedic injuries and how do you avoid missing them?”
Practical approach
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 clinical points
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 pitfalls
Accepting normal X-rays despite high clinical suspicion
Stopping search after finding one injury
Not knowing common missed injury patterns
Further questions
“What is the imaging for suspected scaphoid fracture?”
“What injuries are associated with ACL tears?”
“How do you identify a Lisfranc injury?”
Viva scenarioAdvanced
Occult Fracture and Second-Line Imaging
Clinical prompt
“An 80-year-old woman cannot weight-bear after a fall, but her AP pelvis and lateral hip radiographs look normal. What is your next step and what is the evidence?”
Practical approach
I would not accept the normal radiographs in the face of this clinical picture - an elderly patient unable to weight-bear after a fall has an occult hip fracture until proven otherwise, and a missed femoral neck fracture risks displacement, avascular necrosis and major morbidity. My next step is cross-sectional imaging. MRI is the gold standard for the occult hip fracture because it detects marrow oedema before any cortical change; in a study by Mandell and colleagues, CT had 88% overall sensitivity but only 60% sensitivity for operatively-treated proximal femoral fractures and actually missed a femoral neck fracture that MRI identified. So if MRI is available and the patient can tolerate it, I would obtain a limited MRI of the pelvis and proximal femur. If MRI is contraindicated or unavailable, CT is a reasonable alternative for cortical and trochanteric fractures, but a negative CT does not fully exclude a femoral neck fracture and I would maintain a low threshold to proceed to MRI or repeat assessment. Throughout, I keep the patient non-weight-bearing, manage analgesia and assess for the cause of the fall and medical comorbidities. The same principle applies to the suspected scaphoid fracture, where the Cochrane review found MRI sensitivity around 88% with near-perfect specificity, making it the preferred second-line test over the less specific bone scan.
Key clinical points
Elderly + cannot weight-bear + normal X-ray = occult hip fracture until excluded
MRI is gold standard - detects marrow oedema before cortical change
CT can miss non-displaced femoral neck fractures (sensitivity ~60% for operative neck fractures)
Keep non-weight-bearing and treat the patient, not just the film
Common pitfalls
Discharging on a normal radiograph despite inability to weight-bear
Assuming a negative CT fully excludes a femoral neck fracture
Choosing bone scan first (sensitive but poorly specific, delayed)
Further questions
“Why is MRI preferred over CT for the occult hip fracture?”
“What is the imaging of choice for a suspected scaphoid fracture and why?”
“What are the risks of a missed femoral neck fracture?”
Exam day cheat sheet
Trauma Imaging Exam Day Cheat Sheet
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