Most Common Orthopaedic Questions in FRCEM

Topic priority at a glance

Orthopaedics is a high-yield area in MRCEM and FRCEM because it tests core emergency medicine judgement rather than operative detail. Examiners want safe ED practice: recognising limb-threatening problems, choosing the right imaging, giving timely analgesia, documenting neurovascular findings properly, reducing when appropriate, and referring or discharging safely. The commonest marks come from injuries and complications seen every day in UK emergency departments: open fractures, compartment syndrome, septic arthritis, hip fracture, shoulder dislocation, distal radius fracture, scaphoid injury, ankle trauma, knee dislocation, and occult fractures with normal initial X-rays.

The recurring exam theme is simple: treat the patient, not the film. A normal X-ray does not exclude important injury. Palpable pulses do not exclude compartment syndrome or arterial injury. “Neurovascularly intact” is not enough documentation. If a wound lies near a fracture, think open fracture until proven otherwise. If a joint is hot, swollen and painful, think septic arthritis until excluded. These are the decisions that separate safe candidates from unsafe ones.

Why These Orthopaedic Questions Matter in FRCEM

Musculoskeletal presentations make up a large proportion of ED workload. Most are minor, but a small number are time-critical and limb-threatening. Orthopaedic questions are therefore common in both written and clinical exams because they reflect real emergency practice.

In exam terms, orthopaedics tests whether you can:

• identify red flags early
• prioritise immediate ED actions over definitive orthopaedic management
• choose appropriate imaging and know when plain films are not enough
• perform and document a focused neurovascular examination
• recognise injuries needing urgent reduction, antibiotics, admission or theatre referral
• discharge stable injuries safely with appropriate follow-up and safety-netting

Commonly tested themes include:

• open fracture management
• compartment syndrome
• septic arthritis
• hip fracture and occult hip fracture
• shoulder dislocation, especially missed posterior dislocation
• distal radius fracture reduction and analgesia
• scaphoid injury with normal X-rays
• Ottawa ankle and knee rules
• Lisfranc injury and tibial plateau fracture
• knee dislocation with vascular risk
• paediatric supracondylar fracture and pulled elbow

Key Definitions

Open fracture
A fracture with communication between the fracture and the external environment. Any wound near a fracture should be treated as an open fracture until proven otherwise.

Compartment syndrome
Raised pressure within a closed fascial compartment causing impaired tissue perfusion and risk of muscle and nerve necrosis. It is a clinical diagnosis and a surgical emergency.

Septic arthritis
Infection within a joint space causing rapid cartilage destruction and systemic illness. It requires urgent specialist involvement and usually admission.

Occult fracture
A clinically important fracture not visible on initial plain radiographs.

Neurovascular compromise
Impaired distal perfusion or nerve function associated with a fracture or dislocation. This may require urgent reduction or specialist intervention.

Reduction
Manipulation of a fracture or dislocation to restore alignment. In ED questions, the issue is usually whether reduction is needed urgently and how to do it safely.

Essential Pathophysiology

Most orthopaedic emergencies are dangerous because of one of four mechanisms:

• loss of perfusion, as in arterial injury or compartment syndrome
• progressive soft tissue damage, as in dislocation or unstable fracture
• infection, as in open fracture or septic arthritis
• occult structural instability, where normal initial imaging falsely reassures

Compartment syndrome develops when tissue pressure rises above capillary perfusion pressure. Muscle and nerve ischaemia follow. Pain out of proportion and pain on passive stretch are early signs. Pulselessness is late and unreliable.

Open fractures carry a high risk of contamination, infection and soft tissue injury. Early antibiotics, splintage and specialist referral matter more in the ED than fracture classification.

Septic arthritis rapidly destroys cartilage and may present without dramatic systemic signs, especially in older adults and immunosuppressed patients.

Dislocations can stretch or compress nerves and vessels. Delay in reduction increases pain, swelling and risk of complications. Hip dislocation is particularly time-critical because of the risk of avascular necrosis.

Occult fractures are common where anatomy is complex or overlap obscures injury. Typical examples are scaphoid fracture, occult hip fracture, posterior shoulder dislocation, Lisfranc injury and tibial plateau fracture.

Clinical Presentation

Orthopaedic presentations in the ED usually fall into a few recognisable patterns.

• Pain, swelling and deformity after trauma: think fracture or dislocation
• Pain out of proportion, tense limb, pain on passive stretch: think compartment syndrome
• Hot swollen painful joint with reduced range of movement: think septic arthritis
• Inability to weight bear after a fall, especially in an older adult: think hip fracture even if X-rays are normal
• Wound near a fracture: think open fracture
• Normal AP shoulder film but fixed internal rotation and limited external rotation: think posterior shoulder dislocation
• Midfoot pain after twisting or crush injury with plantar bruising: think Lisfranc injury
• Snuffbox tenderness after a fall onto an outstretched hand: think scaphoid injury even if X-rays are normal

Always ask about mechanism, timing, ability to weight bear or use the limb, anticoagulants, tetanus status where relevant, and baseline mobility or function.

Red Flags and High-Risk Features

The highest-yield orthopaedic red flags are:

• open fracture
• compartment syndrome
• septic arthritis
• dislocation with neurovascular compromise
• knee dislocation or suspected spontaneously reduced knee dislocation
• pelvic fracture with haemodynamic instability
• hip dislocation
• suspected occult hip fracture in a non-weight-bearing patient
• cauda equina or spinal cord symptoms in trauma overlap cases

Specific red flag clues:

Differential Diagnosis

Common differentials that appear in exams include:

• fracture versus dislocation versus severe soft tissue injury
• septic arthritis versus crystal arthropathy versus reactive arthritis
• scaphoid fracture versus wrist sprain
• ankle fracture versus ligamentous injury
• Lisfranc injury versus simple midfoot sprain
• occult hip fracture versus soft tissue hip injury
• compartment syndrome versus severe bruising or post-injury pain
• posterior shoulder dislocation versus frozen shoulder or rotator cuff injury
• tibial plateau fracture versus ligamentous knee injury

In exam stems, the discriminator is usually not the full differential list but the clue that makes one diagnosis unsafe to miss.

Initial ED Assessment

Start with ABCDE in major trauma or any unstable patient. Orthopaedic injuries can distract from life-threatening problems.

For isolated limb injury, a safe ED sequence is:

1. Analgesia early
2. Immobilise or splint
3. Assess skin and look for open fracture
4. Perform and document neurovascular examination
5. Image appropriately
6. Reduce urgently if indicated
7. Repeat and document neurovascular examination after intervention
8. Decide on referral, admission or discharge

Neurovascular assessment must be specific. Document:

• distal pulses and perfusion
• colour, warmth and capillary refill where relevant
• motor function by named nerve
• sensation by named nerve territory
• pain limiting examination if applicable
• findings before and after reduction, splintage or cast application

Examples of high-yield nerve checks:

Do not write only “NVI”. That is poor exam technique and poor documentation.

Investigations

Plain radiographs are first-line for most injuries, but the exam repeatedly tests when plain films are not enough.

Plain radiographs

Request the correct views and include the joint above and below where relevant. Common traps are inadequate views and failure to request additional views for suspected dislocation.

Examples:

• shoulder trauma: AP plus axillary or scapular Y view if dislocation is possible
• wrist trauma: standard wrist series; consider scaphoid views depending on local pathway
• ankle trauma: standard ankle views if Ottawa criteria met
• knee trauma: standard knee views if Ottawa criteria met

Ottawa rules

These are common exam questions. They reduce unnecessary imaging but apply only in appropriate clinical settings and do not replace judgement.

Ottawa ankle rules: ankle X-ray if pain in malleolar zone and any of:

• bony tenderness at posterior edge or tip of lateral malleolus
• bony tenderness at posterior edge or tip of medial malleolus
• inability to bear weight both immediately and in ED for four steps

Foot X-ray if pain in midfoot zone and any of:

• bony tenderness at base of fifth metatarsal
• bony tenderness at navicular
• inability to bear weight both immediately and in ED for four steps

Ottawa knee rule: knee X-ray if acute knee injury and any of:

• age 55 or over
• isolated patellar tenderness
• tenderness at fibular head
• inability to flex knee to 90 degrees
• inability to bear weight for four steps both immediately and in ED

Use caution if assessment is unreliable because of intoxication, communication difficulty, distracting injury or altered mental state.

When X-rays are normal but suspicion remains high

Blood tests

Blood tests are not routine for simple fractures. They are relevant in:

• suspected septic arthritis: FBC, CRP, U&Es, blood cultures if febrile or septic
• major trauma or pelvic injury: trauma bloods, group and save or crossmatch as indicated
• older adults with hip fracture: routine admission bloods and ECG according to pathway

Joint aspiration

Joint aspiration may be required in suspected septic arthritis, usually after discussion with the relevant team and by a clinician competent to perform it. Send aspirate for microscopy, culture and crystal analysis. If the patient is septic or unstable, do not delay antibiotics for aspiration.

Management in the Emergency Department

The exam usually asks for the immediate ED step, not definitive orthopaedic management. A safe answer starts with analgesia, immobilisation, neurovascular assessment and recognition of emergencies.

General ED management sequence

1. ABCDE if major trauma or unstable
2. Give prompt analgesia
3. Immobilise the limb or joint
4. Assess for open fracture and skin compromise
5. Document neurovascular status
6. Image appropriately
7. Reduce urgently if indicated and safe
8. Repeat neurovascular examination and obtain post-reduction imaging where appropriate
9. Refer, admit or discharge with clear follow-up and safety-netting

Analgesia and regional anaesthesia

Analgesia should be proportionate and early. Severe traumatic pain usually needs prompt strong analgesia, often titrated IV opioid, plus splintage and simple analgesics where appropriate. In children or where IV access is delayed, intranasal opioid may be appropriate according to local practice.

Do not delay analgesia until after imaging.

Hip fracture: NICE supports offering a nerve block such as fascia iliaca block for suspected hip fracture, delivered by trained staff under local governance. This is a classic UK exam point. Key safety points are:

• confirm the correct side
• use local procedural safety checks
• calculate local anaesthetic dose carefully
• aspirate and inject incrementally according to technique
• monitor the patient appropriately
• be prepared to recognise and treat local anaesthetic systemic toxicity
• use it as part of a broader analgesic plan, not as the only intervention

Distal radius reduction: for exam purposes, Bier’s block remains a traditional UK answer for suitable closed distal radius reduction where trained staff, monitoring and governance arrangements exist. Real-world practice varies and may include haematoma block or procedural sedation. The best answer depends on the st