A 53-year-old woman with known metastatic breast cancer presents to the Emergency Department with a 4-week history of worsening lower back pain, bilateral leg weakness, and urinary hesitancy that has progressed to urinary retention over the past 24 hours. On examination, power is 2/5 in both legs, there is saddle anaesthesia, and reduced anal tone. An urgent MRI demonstrates cord compression at L1. After commencing high-dose dexamethasone, what is the timeframe within which definitive treatment should be administered to optimise neurological recovery?
Q92
Which anatomical structure forms the boundary between intracapsular and extracapsular neck of femur fractures?
Q93
A 69-year-old woman with a displaced intracapsular neck of femur fracture undergoes a cemented hemiarthroplasty. During cement insertion, she suddenly becomes hypotensive (blood pressure 75/40 mmHg), bradycardic (heart rate 42 bpm), and her oxygen saturations drop to 82%. She rapidly loses consciousness. What is the underlying pathophysiological mechanism of this complication?
Q94
A 44-year-old woman presents with a 5-month history of lower back pain radiating to both buttocks and posterior thighs. The pain is worse after walking 200 metres and is relieved by sitting or leaning forward. She describes having to stop and lean on a shopping trolley for relief. Neurological examination is normal when supine but after walking, she develops reduced sensation in L5 and S1 distributions bilaterally. What is the most likely diagnosis?
Q95
A 76-year-old man undergoes internal fixation with three cannulated screws for an undisplaced Garden II intracapsular neck of femur fracture. On the second postoperative day, he develops sudden onset confusion, tachypnoea (respiratory rate 32/min), and oxygen saturations of 88% on room air. His heart rate is 115 bpm and blood pressure 95/60 mmHg. A petechial rash is noted on his chest. What is the most likely diagnosis?
Q96
What is the blood supply to the femoral head that is derived from the obturator artery and travels through the ligamentum teres?
Q97
A 59-year-old man presents with a 2-week history of progressive lower back pain and new onset urinary retention requiring catheterisation. He has a past medical history of prostate cancer treated with radiotherapy 3 years ago. On examination, he has reduced power (3/5) in both legs, absent ankle reflexes bilaterally, and a palpable bladder. What is the most appropriate immediate management?
Q98
An 83-year-old woman sustains a Garden IV displaced intracapsular neck of femur fracture. She was fully mobile pre-injury using a walking stick outdoors. She has moderate dementia (Abbreviated Mental Test Score 6/10) but recognises family members and cooperates with care. Her comorbidities include hypertension and osteoarthritis of both knees. Which surgical procedure would provide the best functional outcome?
Q99
A 26-year-old man presents to his GP with a 10-week history of lower back pain and stiffness that is worse in the morning and improves with exercise. He reports buttock pain that alternates sides. His father has a history of inflammatory bowel disease. On examination, there is reduced lumbar spine flexion with a Schober's test of 3 cm (normal >5 cm). Which initial investigation would be most appropriate to support the suspected diagnosis?
Q100
A 71-year-old woman presents to the Emergency Department following a fall from standing height. She has severe pain in her right hip and is unable to weight-bear. Examination reveals a shortened and externally rotated right leg. Plain radiograph confirms an intertrochanteric femur fracture with loss of the posteromedial cortical buttress. What is the most appropriate surgical management?
Orthopaedics & MSK UK Medical PG Practice Questions and MCQs
Question 91: A 53-year-old woman with known metastatic breast cancer presents to the Emergency Department with a 4-week history of worsening lower back pain, bilateral leg weakness, and urinary hesitancy that has progressed to urinary retention over the past 24 hours. On examination, power is 2/5 in both legs, there is saddle anaesthesia, and reduced anal tone. An urgent MRI demonstrates cord compression at L1. After commencing high-dose dexamethasone, what is the timeframe within which definitive treatment should be administered to optimise neurological recovery?
A. Within 6 hours of symptom onset
B. Within 24 hours of diagnosis (Correct Answer)
C. Within 48 hours of symptom onset
D. Within 1 week of presentation
E. Within 2 weeks of diagnosis
Explanation: ***Within 24 hours of diagnosis***
- For **Malignant Spinal Cord Compression (MSCC)**, NICE guidelines specify that definitive treatment, such as **surgical decompression** or **radiotherapy**, must be initiated within **24 hours** of MRI confirmation.
- This timeframe is critical for maximizing **neurological recovery**, particularly for regaining motor function and **sphincter control** in patients with acute deterioration.
*Within 6 hours of symptom onset*
- While rapid intervention is essential, the **6-hour window** is more commonly associated with acute **ischaemic stroke** (thrombolysis) or **compartment syndrome**, rather than the standard for MSCC.
- The guidelines for MSCC specifically anchor the 24-hour target to the **time of diagnosis** rather than the initial onset of vague symptoms.
*Within 48 hours of symptom onset*
- Waiting for **48 hours** from symptom onset is inappropriate because symptoms in this patient began **4 weeks ago**, making this timeframe irrelevant to the current emergency.
- Delaying treatment beyond 24 hours from diagnosis significantly increases the risk of **permanent paraplegia** and irreversible loss of bladder function.
*Within 1 week of presentation*
- A **one-week** delay is far too long for an **oncological emergency** and would likely lead to a complete lack of neurological recovery.
- Such a timeframe may be applicable for elective spinal procedures but not for **acute paralysis** or **cauda equina-like symptoms**.
*Within 2 weeks of diagnosis*
- This duration is associated with poor outcomes, as the greatest chance of recovery occurs if the patient is treated while still **ambulatory**.
- By two weeks, the spinal cord damage from **ischaemia** and mechanical compression is usually **permanent** and refractory to late decompression.
Question 92: Which anatomical structure forms the boundary between intracapsular and extracapsular neck of femur fractures?
A. Insertion of the iliofemoral ligament
B. Intertrochanteric line anteriorly and intertrochanteric crest posteriorly
C. Attachment of the hip joint capsule to the femoral neck (Correct Answer)
D. Level of the lesser trochanter
E. Proximal extent of the periosteal covering of the femur
Explanation: ***Attachment of the hip joint capsule to the femoral neck*** - This anatomical landmark serves as the definitive boundary, as any fracture within this **fibrous capsule** is termed intracapsular and carries a high risk of **avascular necrosis**. - The capsule attaches to the **intertrochanteric line** anteriorly but stays roughly 1 cm proximal to the **intertrochanteric crest** posteriorly, defining the intracapsular space. *Insertion of the iliofemoral ligament* - The **iliofemoral ligament** (Bigelow's ligament) is a component of the fibrous capsule and reinforces it anteriorly, but the ligament itself is not the boundary identifier. - While it attaches near the **intertrochanteric line**, the anatomical definition of the fracture type is based on the entire **capsular reflection**, not a single ligament. *Intertrochanteric line anteriorly and intertrochanteric crest posteriorly* - This describes the **anatomical neck-shaft** junction, but the posterior attachment of the capsule occurs **proximal** to the crest. - Relying solely on the crest as a landmark would incorrectly classify the most distal portion of the posterior neck as **intracapsular**, when it is actually extracapsular. *Level of the lesser trochanter* - The **lesser trochanter** is a landmark for **extracapsular fractures**, specifically serving as a reference point for intertrochanteric and subtrochanteric classifications. - Fractures at this level do not disrupt the **retinacular vessels** found within the joint capsule, thus they have better healing potential than neck fractures. *Proximal extent of the periosteal covering of the femur* - The intracapsular neck is notable for its lack of a thick **periosteal layer**, which limits its ability to form a **callus** during fracture healing. - While this histological feature explains why these fractures are prone to **non-union**, the primary surgical boundary is defined by the **capsular attachment** site.
Question 93: A 69-year-old woman with a displaced intracapsular neck of femur fracture undergoes a cemented hemiarthroplasty. During cement insertion, she suddenly becomes hypotensive (blood pressure 75/40 mmHg), bradycardic (heart rate 42 bpm), and her oxygen saturations drop to 82%. She rapidly loses consciousness. What is the underlying pathophysiological mechanism of this complication?
A. Anaphylactic reaction to methylmethacrylate monomer
B. Air embolism from pressurisation of the femoral canal
C. Fat and cement emboli causing pulmonary hypertension and right heart strain (Correct Answer)
D. Acute myocardial infarction due to hypotension and tachycardia
E. Cerebrovascular accident due to paradoxical embolism
Explanation: ***Fat and cement emboli causing pulmonary hypertension and right heart strain***- This patient is experiencing **Bone Cement Implantation Syndrome (BCIS)**, caused by high pressure in the femoral canal forcing **fat, marrow, and cement particles** into the venous system.- These emboli increase **pulmonary vascular resistance**, leading to acute **right heart failure**, which manifests as severe **hypotension, hypoxia, and bradycardia** shortly after cement insertion.*Anaphylactic reaction to methylmethacrylate monomer*- While the monomer can cause direct **vasodilation**, true IgE-mediated anaphylaxis is very rare in this context.- The timing and hemodynamic collapse are more characteristic of **mechanical embolic obstruction** than an allergic reaction.*Air embolism from pressurisation of the femoral canal*- Though **air** can contribute to the embolic load during femoral canal pressurization, it is rarely the sole cause of cardiovascular collapse.- The clinical syndrome of BCIS is primarily driven by a shower of **marrow contents** and fat rather than simple air bubbles.*Acute myocardial infarction due to hypotension and tachycardia*- While hypotension can trigger a **Type 2 MI**, the primary event here is pulmonary hypertension; the patient is also **bradycardic**, not tachycardic.- An MI is a secondary consequence of the **circulatory collapse** caused by the emboli, not the primary pathophysiology of the sudden decline during cementation.*Cerebrovascular accident due to paradoxical embolism*- A **paradoxical embolism** would require a right-to-left shunt (like a patent foramen ovale) and would typically cause **focal neurological deficits**.- The systemic presentation of **hypoxia and hypotension** points towards a catastrophic pulmonary/cardiac event rather than a primary stroke.
Question 94: A 44-year-old woman presents with a 5-month history of lower back pain radiating to both buttocks and posterior thighs. The pain is worse after walking 200 metres and is relieved by sitting or leaning forward. She describes having to stop and lean on a shopping trolley for relief. Neurological examination is normal when supine but after walking, she develops reduced sensation in L5 and S1 distributions bilaterally. What is the most likely diagnosis?
A. Cauda equina syndrome
B. Lumbar spinal stenosis (Correct Answer)
C. Ankylosing spondylitis
D. Bilateral lumbar disc herniation
E. Peripheral vascular disease
Explanation: ***Lumbar spinal stenosis***- Characterized by **neurogenic claudication**, where leg pain and numbness are triggered by walking and relieved by spine flexion (the **'shopping trolley sign'**).- It occurs due to the narrowing of the spinal canal; symptoms worsen with **extension** (standing/walking) and improve as **flexion** (leaning forward) increases canal diameter.*Cauda equina syndrome*- Typically presents acutely with **saddle anesthesia**, **urinary retention**, and loss of anal sphincter tone, which are absent here.- It is a **surgical emergency** characterized by compression of multiple nerve roots, usually not relieved simply by leaning forward.*Ankylosing spondylitis*- Presents as **inflammatory back pain** that is typically worse in the morning and **improves with exercise**, the opposite of this patient's presentation.- Usually affects younger patients and is associated with **spinal stiffness** and sacroiliitis rather than exercise-induced neurological deficits.*Bilateral lumbar disc herniation*- While it can cause bilateral symptoms, it typically presents with **radicular pain** that is often worsened by sitting or coughing rather than walking.- It usually involves a more **constant neuropathic pain** pattern and is less likely to show the classic postural relief seen in stenosis.*Peripheral vascular disease*- Causes **vascular claudication** where pain is relieved simply by **standing still**, whereas neurogenic claudication specifically requires sitting or spinal flexion.- Physical examination would likely show **diminished peripheral pulses** and skin changes (atrophy/coolness), and is not typically associated with postural sensory changes.
Question 95: A 76-year-old man undergoes internal fixation with three cannulated screws for an undisplaced Garden II intracapsular neck of femur fracture. On the second postoperative day, he develops sudden onset confusion, tachypnoea (respiratory rate 32/min), and oxygen saturations of 88% on room air. His heart rate is 115 bpm and blood pressure 95/60 mmHg. A petechial rash is noted on his chest. What is the most likely diagnosis?
A. Pulmonary embolism
B. Bone cement implantation syndrome
C. Acute myocardial infarction
D. Fat embolism syndrome (Correct Answer)
E. Hospital-acquired pneumonia
Explanation: ***Fat embolism syndrome***- This patient presents with the classic triad of **Fat Embolism Syndrome (FES)**: **respiratory distress** (hypoxia, tachypnoea), **neurological deficit** (confusion), and a **petechial rash** on the chest.- FES typically occurs **24-72 hours** after an orthopedic procedure or long bone fracture, like a neck of femur fracture, due to the release of fat globules into the systemic circulation.*Pulmonary embolism*- While PE causes sudden **hypoxia** and **tachypnoea**, it is not typically associated with a **petechial rash** or acute global neurological symptoms like confusion.- PE usually presents slightly later in the postoperative course unless a **deep vein thrombosis (DVT)** was already present, and the rash is a key differentiating feature.*Bone cement implantation syndrome*- This involves hypoxia and hypotension occurring specifically during the **intraoperative period** at the time of cementation for arthroplasty.- This patient underwent **internal fixation with screws** without the use of bone cement, making this diagnosis impossible.*Acute myocardial infarction*- MI would typically present with **chest pain**, ECG changes, and elevated cardiac biomarkers like **troponins**.- While surgery can trigger a cardiac event, the specific triad of **hypoxia, confusion, and petechiae** is not characteristic of an acute myocardial infarction.*Hospital-acquired pneumonia*- HAP usually presents after **48 hours** with productive cough, fever, and focal consolidation on a chest X-ray.- It does not explain the **petechial rash** or the acute sudden onset of global neurological confusion seen here.
Question 96: What is the blood supply to the femoral head that is derived from the obturator artery and travels through the ligamentum teres?
A. Superior gluteal artery
B. Medial circumflex femoral artery
C. Lateral circumflex femoral artery
D. Artery of ligamentum teres (Correct Answer)
E. Inferior gluteal artery
Explanation: ***Artery of ligamentum teres***
- This vessel, also known as the **foveal artery**, is a branch of the **obturator artery** that travels within the **ligamentum teres** to supply the femoral head.
- While it provides a significant portion of blood supply in **children**, its contribution in adults is minimal, typically accounting for only **10-15%** of femoral head vascularity.
*Superior gluteal artery*
- This artery exits the pelvis through the **greater sciatic foramen** and primarily supplies the **gluteus medius** and **gluteus minimus** muscles.
- It does not travel through the ligamentum teres or provide direct blood supply to the **femoral head**.
*Medial circumflex femoral artery*
- This is the **dominant blood supply** to the adult femoral head, providing approximately **70%** of its vascularity via the **retinacular vessels**.
- It originates from the **profunda femoris** and is frequently damaged in **intracapsular hip fractures**, leading to **avascular necrosis**.
*Lateral circumflex femoral artery*
- This artery primarily supplies the **femoral neck**, greater trochanter, and the **vastus lateralis** muscle.
- It contributes to the extracapsular **arterial ring** at the base of the femoral neck but does not supply the head via the ligamentum teres.
*Inferior gluteal artery*
- This vessel supplies the **gluteus maximus** muscle and contributes to the **cruciate anastomosis** of the thigh.
- It does not enter the hip joint capsule to provide nutrients to the **articular surface** of the femoral head.
Question 97: A 59-year-old man presents with a 2-week history of progressive lower back pain and new onset urinary retention requiring catheterisation. He has a past medical history of prostate cancer treated with radiotherapy 3 years ago. On examination, he has reduced power (3/5) in both legs, absent ankle reflexes bilaterally, and a palpable bladder. What is the most appropriate immediate management?
A. Urgent MRI whole spine within 24 hours
B. Prostate-specific antigen testing and urology referral
C. CT lumbar spine and referral to spinal surgery within 1 week
D. Lumbar spine radiographs and routine orthopaedic referral
E. Commence high-dose oral dexamethasone and arrange urgent MRI (Correct Answer)
Explanation: ***Commence high-dose oral dexamethasone and arrange urgent MRI***
- The patient's presentation with progressive back pain, new urinary retention, bilateral leg weakness, absent ankle reflexes, and a history of prostate cancer strongly indicates **metastatic spinal cord compression (MSCC)** or severe **cauda equina syndrome**.
- Immediate administration of **high-dose dexamethasone** is crucial to reduce peritumoural oedema, followed by an **urgent MRI of the whole spine** to localize the compression and guide definitive treatment.
*Urgent MRI whole spine within 24 hours*
- While an **urgent MRI** is indispensable for diagnosis, it should not precede the immediate administration of **corticosteroids**.
- Delaying steroid therapy can lead to irreversible **neurological damage** by allowing peritumoural oedema to worsen spinal cord compression.
*Prostate-specific antigen testing and urology referral*
- **PSA testing** and urology referral address the underlying cancer but do not provide immediate management for the acute neurological emergency.
- This approach would result in a critical delay in treating **spinal cord compression**, risking permanent **paraplegia** and loss of bladder/bowel function.
*CT lumbar spine and referral to spinal surgery within 1 week*
- A **CT scan** is inferior to MRI for visualizing soft tissues like the spinal cord and nerve roots, making it less suitable for diagnosing compression.
- A 1-week timeline for referral is unacceptable for such a severe neurological presentation, which requires **immediate intervention**.
*Lumbar spine radiographs and routine orthopaedic referral*
- **Plain radiographs** have poor sensitivity for detecting soft tissue compression of the spinal cord and cannot effectively rule out metastatic disease.
- A **routine referral** is inappropriate for red-flag symptoms of **cauda equina syndrome** or MSCC, which necessitate emergency hospital admission and management.
Question 98: An 83-year-old woman sustains a Garden IV displaced intracapsular neck of femur fracture. She was fully mobile pre-injury using a walking stick outdoors. She has moderate dementia (Abbreviated Mental Test Score 6/10) but recognises family members and cooperates with care. Her comorbidities include hypertension and osteoarthritis of both knees. Which surgical procedure would provide the best functional outcome?
A. Cannulated screw fixation
B. Uncemented hemiarthroplasty
C. Cemented hemiarthroplasty
D. Uncemented total hip replacement
E. Cemented total hip replacement (Correct Answer)
Explanation: ***Cemented total hip replacement***
- According to **NICE guidelines**, patients who were able to **walk independently outdoors** (with no more than a stick) and are medically fit should be offered a total hip replacement (THR) over a hemiarthroplasty.
- **Cemented fixation** is preferred in elderly patients to reduce the risk of **periprosthetic fractures**, minimize postoperative pain, and ensure better long-term implant stability.
*Cannulated screw fixation*
- This approach is generally reserved for **undisplaced (Garden I and II)** fractures; in a **Garden IV displaced** fracture, the risk of **non-union** and **avascular necrosis** is unacceptably high.
- Displaced fractures in patients over 65 are routinely managed with **arthroplasty** rather than internal fixation to allow for immediate weight-bearing.
*Uncemented hemiarthroplasty*
- **Uncemented implants** in the elderly are associated with a higher risk of **intraoperative fractures** and increased mid-term postoperative thigh pain compared to cemented options.
- Large randomized trials have demonstrated that **cemented arthroplasty** provides superior functional outcomes and lower mortality in this age group.
*Cemented hemiarthroplasty*
- While a reasonable alternative, this patient meets the criteria for THR because she was **independently mobile** outdoors and her **Abbreviated Mental Test Score (6/10)** does not represent severe cognitive impairment.
- THR provides superior **long-term functional outcomes** and lower rates of reoperation due to **acetabular erosion** compared to hemiarthroplasty.
*Uncemented total hip replacement*
- Similar to hemiarthroplasty, **uncemented THR** carries a significantly higher risk of **periprosthetic femoral fracture** in osteoporotic elderly bone.
- Standard evidence-based practice favors **cemented components** to ensure better initial stability and a more reliable bond between the bone and the prosthesis.
Question 99: A 26-year-old man presents to his GP with a 10-week history of lower back pain and stiffness that is worse in the morning and improves with exercise. He reports buttock pain that alternates sides. His father has a history of inflammatory bowel disease. On examination, there is reduced lumbar spine flexion with a Schober's test of 3 cm (normal >5 cm). Which initial investigation would be most appropriate to support the suspected diagnosis?
A. MRI lumbar spine (Correct Answer)
B. HLA-B27 testing
C. Plain radiograph of sacroiliac joints
D. Erythrocyte sedimentation rate and C-reactive protein
E. Rheumatoid factor and anti-CCP antibodies
Explanation: ***MRI lumbar spine***
- **MRI** is the gold standard for detecting **early inflammatory changes** like **bone marrow oedema** in axial spondyloarthritis (e.g., Ankylosing Spondylitis) before structural damage appears on X-rays.
- Given the patient's strong clinical picture of inflammatory back pain, including reduced **lumbar spine flexion** (Schober's test 3 cm) and alternating buttock pain, MRI is the most sensitive investigation to confirm **active sacroiliitis** in early-stage disease.
*HLA-B27 testing*
- While **HLA-B27** is strongly associated with Ankylosing Spondylitis, it is present in 8% of the healthy population and is not diagnostic on its own.
- It is useful for supporting a diagnosis in borderline cases or for risk stratification but does not provide direct visual evidence of **sacroiliitis** or spinal inflammation.
*Plain radiograph of sacroiliac joints*
- Radiographs only detect **chronic structural changes** such as erosions, sclerosis, or joint fusion, which may take years to develop.
- It is often normal in the early phases of **axial spondyloarthritis** and lacks the sensitivity to detect acute inflammation compared to MRI.
*Erythrocyte sedimentation rate and C-reactive protein*
- **ESR and CRP** are non-specific markers of systemic inflammation that may be elevated in **spondyloarthropathies** but are not diagnostic.
- A significant portion of patients with active **Ankylosing Spondylitis** may have normal inflammatory markers, reducing their utility as a primary diagnostic tool.
*Rheumatoid factor and anti-CCP antibodies*
- These tests are specific for **Rheumatoid Arthritis**, a different condition typically involving small peripheral joints, and worsening with rest rather than improving with exercise.
- These markers are typically negative in **seronegative spondyloarthropathies** like Ankylosing Spondylitis, making them unhelpful for this suspected diagnosis.
Question 100: A 71-year-old woman presents to the Emergency Department following a fall from standing height. She has severe pain in her right hip and is unable to weight-bear. Examination reveals a shortened and externally rotated right leg. Plain radiograph confirms an intertrochanteric femur fracture with loss of the posteromedial cortical buttress. What is the most appropriate surgical management?
A. Dynamic hip screw fixation
B. Cannulated screw fixation
C. Cemented hemiarthroplasty
D. Intramedullary femoral nail (Correct Answer)
E. Total hip replacement
Explanation: ***Intramedullary femoral nail*** - Loss of the **posteromedial cortical buttress** indicates an **unstable** intertrochanteric fracture pattern, which requires more robust biomechanical support. - An **intramedullary device** (cephalomedullary nail) provides a shorter lever arm and better **load-sharing** capabilities than extramedullary devices in unstable fractures.*Dynamic hip screw fixation* - This is the treatment of choice for **stable** intertrochanteric fractures where the medial cortex remains intact. - In unstable patterns, such as this one, it is associated with a higher risk of **excessive collapse**, medialization of the shaft, and **implant failure**.*Cannulated screw fixation* - This technique is specifically used for **undisplaced or stable intracapsular** femoral neck fractures. - It does not provide sufficient stability or strength for **extracapsular** intertrochanteric injuries.*Cemented hemiarthroplasty* - While used frequently for **displaced intracapsular** fractures in the elderly, it is not standard primary management for intertrochanteric fractures. - Intertrochanteric bone is highly vascular with high **healing potential**, making internal fixation preferable over replacing the joint.*Total hip replacement* - Reserved for patients with pre-existing **hip osteoarthritis** or very specific complex intracapsular fractures in active older adults. - It is a more extensive procedure than necessary for an **intertrochanteric fracture**, which is better managed by preserving the native joint via nail fixation.
