MSK Red Flag OSCE Guide
The questions you must not miss in back pain and joint pain.
This guide builds on the general MSK History OSCE Guide.
In a standard MSK history, explore the presenting symptom, identify the likely pattern and assess function. This page focuses specifically on recognising serious pathology and asking red-flag questions clearly
What this Station is Testing?
In an MSK red-flags station, the examiner wants to see that you can:
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Screen for cauda equina syndrome in plain language
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Recognise possible malignancy, infection or fracture
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Identify progressive neurological symptoms
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Recognise a possible septic joint
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Escalate urgently when red flags are present
OSCE Talk Tip
The key red flag areas are:
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Bladder, bowel, sexual or saddle symptoms
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Bilateral or progressive neurological symptoms
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Cancer, infection and fracture risk
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A red, hot, severely painful joint
Cauda Equina Syndrome
Cauda equina syndrome occurs when the nerves at the bottom of the spinal canal become compressed.
Immediately refer patients with severe back pain radiating into the leg alongside new bladder, bowel or sexual dysfunction or new numbness around the perineum.
Screen for it whenever back pain is associated with new neurological or bilateral leg symptoms
Saddle Sensation
“Have you noticed any new numbness or altered feeling around your inner thighs, genitals, bottom or back passage?”
“Can you feel normally when sitting on the toilet or wiping yourself?”
Bladder Symptoms
Do not ask only about incontinence.
Cauda equina syndrome may cause difficulty starting urination, retention or loss of normal bladder sensation.
“Have you developed any difficulty starting to pass urine?”
“Can you still feel normally when your bladder is full?”
“Do you feel that your bladder is emptying properly?”
“Have you had any new leakage or accidents?”
Bowel and Sexual Symptoms
“Have you had any new difficulty controlling your bowels or knowing when you need to go?”
Signpost personal questions:
“I need to ask a personal question because these nerves also control sexual function.”
“Have you noticed any new loss of genital sensation or change in sexual function?”
Adapt the wording to the patient.
“Does the pain travel down one leg or both? ”
“Have you developed any numbness, tingling or weakness?”
“Are your legs giving way?”
“Has your walking changed?”
Bilateral symptoms, progressive weakness, saddle sensory changes and bladder or bowel dysfunction require urgent assessment.
Leg Symptoms
Other Serious Causes of Back Pain
After screening for cauda equina syndrome, briefly consider malignancy, infection and fracture.
Tailor the questions to what has already been covered rather than repeating the history.
Useful questions include:
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“Have you ever been diagnosed with cancer or lost weight without trying?”
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“Have you had any fever, recent infection or procedure, or do you take medication that suppresses your immune system?”
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“Was there any fall or injury, and do you have osteoporosis or take long-term steroid tablets?”
Progressive pain, pain that remains severe at rest or at night, systemic illness, significant trauma or new neurological symptoms should increase concern.
These features do not confirm a diagnosis on their own, but they may require urgent assessment for malignancy, spinal infection or fracture.
Do Not Miss Septic Arthritis
A short history of a severely painful, hot, swollen joint with restricted movement should raise concern about septic arthritis.
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“Did the pain and swelling come on suddenly?”
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“Has the joint become hot or red?”
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“Are you able to move it or put weight through it?”
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“Have you had a fever or felt generally unwell?”
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“Have you recently had an infection, operation or injection?”
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“Do you have an artificial joint?”
Risk is increased by:
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A prosthetic joint
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Recent joint surgery or injection
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Immunosuppression
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Diabetes
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Recent infection
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Intravenous drug use
Suspected septic arthritis, or a hot swollen joint where it cannot be safely excluded, requires immediate specialist assessment. The absence of fever does not rule it out.
Example Summary
“Peter is a 52-year-old man presenting with a three-day history of severe lower-back pain radiating into both legs. He reports progressive bilateral leg numbness, new altered sensation around the back passage and difficulty sensing when his bladder is full. He is also struggling to walk because of leg weakness. These features are concerning for cauda equina syndrome, and I would arrange immediate senior review and emergency spinal assessment.”
Examiner Questions
Q1: What serious diagnoses should be considered in back pain?
Cauda equina syndrome, spinal cord compression, malignancy, infection and fracture.
Q2: What features suggest Cauda Equina Syndrome?
New saddle sensory changes, bladder or bowel dysfunction, sexual dysfunction, bilateral sciatica or progressive leg weakness.
Q3: Why should you not ask only about Urinary Incontinence?
Cauda equina syndrome may initially cause retention, difficulty starting or loss of bladder sensation.
Q4: What features suggest malignancy?
Previous cancer, unexplained weight loss, progressive pain and new neurological symptoms.
Q5: What features suggest spinal infection?
Systemic illness, immunosuppression, recent infection or procedure, intravenous drug use and severe persistent pain.
Q6: What features suggest septic arthritis?
An acutely painful, hot, swollen joint with restricted movement.
Q7: Does the absence of fever exclude septic arthritis?
No.
Q8: What should you do if red flags are present?
Escalate urgently and arrange emergency assessment and appropriate investigation.
Quick Structure
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Ask about neurological and bilateral leg symptoms
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Ask about saddle sensation
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Ask about bladder, bowel and sexual function
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Screen for cancer, infection and fracture
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Recognise the red, hot, swollen joint
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Escalate urgently when red flags are present
