Orthopaedics & MSK — MCQs
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A 67-year-old woman presents with a 6-week history of lower back pain radiating to both legs. The pain is worse on walking and relieved by sitting or leaning forward. She reports that she can walk further when pushing a shopping trolley. Peripheral pulses are normal. What is the most likely diagnosis?
A 58-year-old man with a history of tuberculosis 20 years ago presents with a 4-month history of progressively worsening lower back pain. The pain is constant, worse at night, and not relieved by rest. He reports unintentional weight loss of 8 kg and night sweats. ESR is 78 mm/hr and CRP is 45 mg/L. What is the most likely underlying diagnosis?
Which of the following best describes the Garden classification system for intracapsular neck of femur fractures?
A 74-year-old woman sustains a neck of femur fracture following a fall. An anteroposterior pelvic radiograph shows a fracture line extending from the femoral head-neck junction towards the greater trochanter, located entirely distal to the insertion of the hip joint capsule. Which anatomical classification best describes this fracture pattern?
A 52-year-old man with a 15-year history of chronic lower back pain presents with new onset bilateral leg weakness, saddle paraesthesia, and urinary retention that developed over 24 hours. On examination, there is bilateral leg weakness (4/5), absent ankle reflexes, reduced perianal sensation, and a palpable bladder. Post-void residual volume is 800 ml. What is the timeframe within which surgical decompression should ideally be performed to optimize neurological recovery?
A 71-year-old man sustains an undisplaced basicervical neck of femur fracture. He is cognitively intact, independently mobile, and medically fit. Surgical management is planned. Which fixation device is most biomechanically appropriate for this fracture pattern?
A 35-year-old man presents to the Emergency Department with sudden onset severe lower back pain that began 3 hours ago when lifting furniture. He describes the pain as 7/10 in severity, localized to the lumbar region with no radiation. He can walk, has no bladder or bowel symptoms, and neurological examination is completely normal. He is apyrexial. What is the most appropriate immediate management?
A 76-year-old woman with a displaced intracapsular neck of femur fracture undergoes cemented hemiarthroplasty. She has a history of chronic kidney disease stage 4 (eGFR 25 ml/min/1.73m²). Post-operatively, the multidisciplinary team is planning thromboprophylaxis. What is the most appropriate thromboprophylaxis regimen for this patient?
A 43-year-old woman presents with a 12-week history of lower back pain radiating to the lateral aspect of her right thigh and leg. She describes tingling over the dorsum of her foot and reports difficulty with foot dorsiflexion when walking. Examination reveals weakness of right ankle dorsiflexion (4/5 power), diminished sensation over the first web space, and a positive straight leg raise at 40 degrees on the right. What is the most likely nerve root affected?
A 68-year-old man undergoes dynamic hip screw fixation for an intertrochanteric femur fracture. Post-operatively, the tip-apex distance (TAD) is measured on the AP and lateral radiographs. What is the maximum acceptable tip-apex distance to minimize the risk of screw cut-out?
Orthopaedics & MSK UK Medical PG Practice Questions and MCQs
Question 151: A 67-year-old woman presents with a 6-week history of lower back pain radiating to both legs. The pain is worse on walking and relieved by sitting or leaning forward. She reports that she can walk further when pushing a shopping trolley. Peripheral pulses are normal. What is the most likely diagnosis?
- A. Lumbar disc herniation with bilateral radiculopathy
- B. Peripheral vascular disease with intermittent claudication
- C. Lumbar spinal stenosis with neurogenic claudication (Correct Answer)
- D. Cauda equina syndrome
- E. Degenerative spondylolisthesis
Explanation: ***Lumbar spinal stenosis with neurogenic claudication***- The classic **'shopping trolley sign'** occurs because leaning forward (lumbar flexion) increases the **cross-sectional area** of the spinal canal, relieving pressure on the neural elements.- This patient presents with **neurogenic claudication**, characterized by bilateral leg pain induced by walking and relieved by sitting or leaning forward, typically seen in older patients with **degenerative changes**.*Lumbar disc herniation with bilateral radiculopathy*- This typically presents with **acute onset** of pain that is often **worsened by flexion** (sitting or bending forward), which is the opposite of this patient's presentation.- Bilateral radiculopathy from a disc is rare and usually associated with a large **central disc protrusion** rather than chronic walking-induced symptoms.*Peripheral vascular disease with intermittent claudication*- While both cause leg pain on walking, vascular claudication is relieved simply by **standing still**, whereas neurogenic claudication requires **spinal flexion** (sitting or leaning).- The presence of **normal peripheral pulses** and the 'shopping trolley sign' effectively rule out peripheral arterial disease as the cause.*Cauda equina syndrome*- This is a surgical emergency characterized by **saddle anesthesia**, **bladder/bowel dysfunction** (e.g., urinary retention), and profound motor weakness.- While stenosis can lead to this, the patient's 6-week history of **position-dependent pain** without neurological emergencies makes it an unlikely primary diagnosis.*Degenerative spondylolisthesis*- Although this condition can lead to spinal stenosis, it refers specifically to the **slippage of one vertebra** over another, usually seen at the L4-L5 level.- While it is a potential cause, **lumbar spinal stenosis** is the most accurate clinical description for the syndrome of neurogenic claudication described.
Question 152: A 58-year-old man with a history of tuberculosis 20 years ago presents with a 4-month history of progressively worsening lower back pain. The pain is constant, worse at night, and not relieved by rest. He reports unintentional weight loss of 8 kg and night sweats. ESR is 78 mm/hr and CRP is 45 mg/L. What is the most likely underlying diagnosis?
- A. Mechanical lower back pain with deconditioning
- B. Ankylosing spondylitis
- C. Spinal tuberculosis (Pott's disease) (Correct Answer)
- D. Metastatic spinal malignancy
- E. Lumbar disc prolapse with radiculopathy
Explanation: ***Spinal tuberculosis (Pott's disease)***- The patient's history of **prior tuberculosis**, combined with **constitutional symptoms** like night sweats and weight loss, strongly suggests reactivation of TB in the spine.- The **elevated inflammatory markers** (ESR/CRP) and **nocturnal pain** that is not relieved by rest are classic red flags for an infectious or inflammatory process like **Pott's disease**.*Mechanical lower back pain with deconditioning*- **Mechanical back pain** is typically relieved by rest and does not present with **systemic symptoms** like weight loss or night sweats.- It would not explain the significantly elevated **ESR and CRP** levels seen in this clinical presentation.*Ankylosing spondylitis*- This condition usually presents in **younger patients** and is characterized by pain and stiffness that **improves with activity**, unlike this patient's worsening symptoms.- While it involves the spine, it does not typically cause **unintentional weight loss** or follow a history of tuberculosis infection.*Metastatic spinal malignancy*- While malignancy causes **nocturnal pain** and weight loss, the 20-year history of **tuberculosis** makes infectious spondylitis a more specific consideration.- Distinguishing between the two often requires imaging and biopsy, but the **prior TB exposure** serves as a strong diagnostic clue for Pott's disease.*Lumbar disc prolapse with radiculopathy*- This typically presents with **acute onset** radicular pain (sciatica) following a dermatomal pattern rather than **constant night pain**.- Disc prolapse is a mechanical issue and is not associated with **fever**, night sweats, or elevated systemic **inflammatory markers**.
Question 153: Which of the following best describes the Garden classification system for intracapsular neck of femur fractures?
- A. Classification based on the anatomical location of the fracture relative to the trochanters
- B. Classification based on the degree of displacement and alignment of trabecular patterns on anteroposterior radiograph (Correct Answer)
- C. Classification based on the angle of the fracture line relative to the horizontal plane
- D. Classification based on the mechanism of injury and patient age
- E. Classification based on the presence or absence of comminution at the fracture site
Explanation: ***Classification based on the degree of displacement and alignment of trabecular patterns on anteroposterior radiograph*** - The **Garden Classification** uses the alignment of the **medial femoral neck trabeculae** on an AP radiograph to categorize intracapsular fractures into four stages (I to IV). - It is critical for clinical decision-making, specifically distinguishing between **undisplaced** (I and II) and **displaced** (III and IV) fractures, which guides surgical approach and assesses the risk of **avascular necrosis**. *Classification based on the anatomical location of the fracture relative to the trochanters* - This describes broader **anatomical classifications** of hip fractures (e.g., subcapital, transcervical, basicervical, intertrochanteric, subtrochanteric) rather than the specific Garden system. - The Garden system specifically applies to **intracapsular** fractures and categorizes them based on displacement, not their general position relative to the trochanters. *Classification based on the angle of the fracture line relative to the horizontal plane* - This describes the **Pauwels classification**, which assesses the **verticality** or shear angle of the fracture line. - Higher Pauwels angles (Type III) indicate greater **shear forces** and a higher risk of non-union, whereas Garden focuses on the degree of displacement and impaction. *Classification based on the mechanism of injury and patient age* - While patient age and **mechanism of injury** (e.g., high-energy trauma vs. low-energy fall) are crucial for overall clinical assessment and treatment planning, they are not the criteria used for the Garden radiographic classification. - The Garden system relies purely on **radiographic signs** of displacement and trabecular alignment to grade the fracture. *Classification based on the presence or absence of comminution at the fracture site* - **Comminution** (fragmentation) is an important feature in classifying many fractures, particularly **extracapsular fractures** like those using the Evans classification for intertrochanteric fractures. - The Garden classification, however, focuses on the **angular displacement** and impaction of the femoral head relative to the neck, rather than the number or size of bone fragments.
Question 154: A 74-year-old woman sustains a neck of femur fracture following a fall. An anteroposterior pelvic radiograph shows a fracture line extending from the femoral head-neck junction towards the greater trochanter, located entirely distal to the insertion of the hip joint capsule. Which anatomical classification best describes this fracture pattern?
- A. Intracapsular subcapital fracture
- B. Intracapsular transcervical fracture
- C. Basicervical fracture
- D. Intertrochanteric fracture (Correct Answer)
- E. Subtrochanteric fracture
Explanation: ***Intertrochanteric fracture***- These fractures occur between the **greater and lesser trochanters** and are located **extracapsularly**, distal to the hip joint capsule insertion.- Because they are outside the capsule, they have a **better blood supply** and lower risk of avascular necrosis compared to intracapsular fractures.*Intracapsular subcapital fracture*- This fracture occurs immediately **distal to the femoral head** and is located entirely within the joint capsule.- It carries a high risk of **avascular necrosis** due to disruption of the primary blood supply to the femoral head.*Intracapsular transcervical fracture*- Located across the **mid-portion of the femoral neck**, this pattern remains within the hip joint capsule.- Like other intracapsular fractures, it is associated with a high rate of **non-union** and damage to the retinacular vessels.*Basicervical fracture*- This fracture occurs at the **base of the femoral neck** exactly at the junction of the neck and the trochanters.- Since it occurs at the **capsular insertion line**, it is often biomechanically treated similarly to extracapsular fractures.*Subtrochanteric fracture*- This pattern describes a fracture located in the region **distal to the lesser trochanter**, extending into the proximal femoral shaft.- These are characterized by high mechanical stress and are typically managed with **intramedullary nails**.
Question 155: A 52-year-old man with a 15-year history of chronic lower back pain presents with new onset bilateral leg weakness, saddle paraesthesia, and urinary retention that developed over 24 hours. On examination, there is bilateral leg weakness (4/5), absent ankle reflexes, reduced perianal sensation, and a palpable bladder. Post-void residual volume is 800 ml. What is the timeframe within which surgical decompression should ideally be performed to optimize neurological recovery?
- A. Within 6 hours of symptom onset
- B. Within 24 hours of symptom onset
- C. Within 48 hours of symptom onset (Correct Answer)
- D. Within 72 hours of symptom onset
- E. Within 1 week of symptom onset
Explanation: ***Within 48 hours of symptom onset*** - This timeframe is crucial for **Cauda Equina Syndrome (CES)**, as surgical decompression within **48 hours** is strongly associated with improved recovery of **bladder, bowel, and motor functions**. - Early intervention within this window aims to prevent **irreversible neurological damage** by relieving pressure on the cauda equina nerves. *Within 6 hours of symptom onset* - While earlier decompression is often desired, a **6-hour window** is not a universally accepted or practical guideline for optimal recovery in CES, which can be challenging to diagnose rapidly. - This very tight timeframe is not supported by current evidence as being significantly superior to the **48-hour** window for overall neurological outcomes. *Within 24 hours of symptom onset* - Decompression within **24 hours** is considered excellent and generally yields very good outcomes, particularly if **complete urinary retention** has not yet occurred. - However, the critical threshold for significantly worsening prognosis is often cited as beyond **48 hours**, making 24 hours an ideal but not strictly mandatory cutoff for optimal results compared to the 48-hour benchmark. *Within 72 hours of symptom onset* - Delaying surgical decompression beyond **48 hours** and into the **72-hour** mark significantly increases the risk of permanent **neurological deficits**, including persistent **urinary and bowel dysfunction** and sensory loss. - The chances of achieving full recovery of **bladder and bowel function** diminish substantially with such delays. *Within 1 week of symptom onset* - Surgical intervention after **one week** is considered a **late decompression** and is often associated with poor recovery of **sphincter function** and significant residual **motor and sensory deficits**. - Prolonged compression for this duration frequently leads to **irreversible nerve damage** and permanent disability.
Question 156: A 71-year-old man sustains an undisplaced basicervical neck of femur fracture. He is cognitively intact, independently mobile, and medically fit. Surgical management is planned. Which fixation device is most biomechanically appropriate for this fracture pattern?
- A. Cannulated hip screws
- B. Dynamic hip screw with derotation screw (Correct Answer)
- C. Intramedullary nail
- D. Total hip replacement
- E. Proximal femoral locking plate
Explanation: ***Dynamic hip screw with derotation screw***- **Basicervical fractures** are biomechanically unstable fractures at the base of the femoral neck, resembling **extracapsular** patterns, which benefit from the controlled **sliding compression** and lateral plate support provided by a **Dynamic Hip Screw (DHS)**.- An additional **derotation screw** prevents rotational instability of the femoral head during and after fixation, ensuring enhanced stability and improving healing potential. *Cannulated hip screws*- These screws are best suited for **undisplaced intracapsular** fractures (subcapital or transcervical) where the fracture geometry allows for stable compression.- They lack the **lateral plate** that provides essential buttress support against **varus collapse** common in basicervical fractures, making them biomechanically inadequate for this fracture pattern. *Intramedullary nail*- **Intramedullary nails** are primarily indicated for **subtrochanteric** or unstable **intertrochanteric fractures**, especially those with a **reverse oblique** component.- For a simple undisplaced basicervical fracture, a **DHS** is typically sufficient and often less invasive than an intramedullary nail, which may introduce greater surgical morbidity without additional biomechanical advantage for this specific fracture. *Total hip replacement*- This procedure is usually reserved for **displaced intracapsular** fractures in elderly patients or those with significant **pre-existing osteoarthritis** or poor bone quality, to mitigate the risk of **avascular necrosis**.- For an **undisplaced fracture** in a cognitively intact, independently mobile patient, the goal is to preserve the native hip joint through **internal fixation**, not immediate arthroplasty. *Proximal femoral locking plate*- **Locking plates** provide a rigid construct that may lead to **stress shielding**, potentially hindering the natural biological healing process which benefits from controlled micromotion.- They are typically reserved for **complex comminuted fractures**, **periprosthetic fractures**, or **revision surgeries** where other fixation methods have failed, not as a primary treatment for a basicervical fracture.
Question 157: A 35-year-old man presents to the Emergency Department with sudden onset severe lower back pain that began 3 hours ago when lifting furniture. He describes the pain as 7/10 in severity, localized to the lumbar region with no radiation. He can walk, has no bladder or bowel symptoms, and neurological examination is completely normal. He is apyrexial. What is the most appropriate immediate management?
- A. Urgent MRI lumbar spine
- B. Plain radiographs of lumbar spine
- C. Analgesia, reassurance, and advice to remain active (Correct Answer)
- D. Strict bed rest for 2 weeks
- E. Referral to spinal surgery
Explanation: ***Analgesia, reassurance, and advice to remain active*** - The patient presents with **acute mechanical lower back pain** following a physical strain, without any **red flag features** such as neurological deficits, fever, bladder/bowel dysfunction, or pain radiating below the knee. - Current guidelines for acute non-specific low back pain emphasize **pain management**, **reassurance**, and encouraging **early mobilization** and return to normal activities, as this promotes faster recovery and reduces chronicity. *Urgent MRI lumbar spine* - **Urgent MRI** is indicated only when there are **red flag symptoms** suggesting serious pathology like **cauda equine syndrome**, malignancy, or spinal infection, none of which are present here. - Routine imaging for acute, uncomplicated back pain rarely changes management and can lead to **unnecessary anxiety** and investigations due to incidental findings. *Plain radiographs of lumbar spine* - **Plain radiographs** are generally not recommended for acute low back pain in the absence of trauma or suspicion of conditions like **vertebral fracture**, infection, or malignancy. - They have **limited utility** for soft tissue abnormalities (like disc herniation) and expose the patient to **radiation** without significant clinical benefit in this scenario. *Strict bed rest for 2 weeks* - **Strict bed rest** is contraindicated for acute low back pain as it can delay recovery, lead to **deconditioning**, muscle weakness, and increased risk of **chronic pain**. - Maintaining activity within pain limits and **early mobilization** are crucial for recovery and preventing long-term disability. *Referral to spinal surgery* - **Referral to spinal surgery** is typically reserved for patients with progressive **neurological deficits**, **cauda equine syndrome**, or severe, intractable pain that has failed prolonged conservative management. - Given the patient's **normal neurological examination** and acute presentation, surgical intervention is not indicated at this stage.
Question 158: A 76-year-old woman with a displaced intracapsular neck of femur fracture undergoes cemented hemiarthroplasty. She has a history of chronic kidney disease stage 4 (eGFR 25 ml/min/1.73m²). Post-operatively, the multidisciplinary team is planning thromboprophylaxis. What is the most appropriate thromboprophylaxis regimen for this patient?
- A. Low molecular weight heparin at full treatment dose
- B. Unfractionated heparin subcutaneously (Correct Answer)
- C. Rivaroxaban 10 mg once daily
- D. Aspirin 75 mg once daily
- E. Mechanical prophylaxis only with intermittent pneumatic compression
Explanation: ***Unfractionated heparin subcutaneously*** - In patients with **severe renal impairment** (eGFR <30 ml/min/1.73m²), **Unfractionated Heparin (UFH)** is the preferred pharmacological agent as it is not primarily eliminated by the kidneys. - This avoids the risk of **drug accumulation** and subsequent major bleeding complications that occur with renally excreted anticoagulants in CKD stage 4 patients. *Low molecular weight heparin at full treatment dose* - **Low molecular weight heparin (LMWH)** is predominantly **renally excreted**, and its half-life is significantly prolonged in patients with an eGFR below 30. - Furthermore, **prophylactic doses**, not full treatment doses, are indicated for post-operative VTE prevention in stable patients. *Rivaroxaban 10 mg once daily* - This **Direct Oral Anticoagulant (DOAC)** is contraindicated or not recommended for VTE prophylaxis when the **eGFR is less than 30 ml/min/1.73m²**. - Using DOACs in severe CKD significantly increases the **risk of hemorrhage** due to decreased renal clearance of the drug. *Aspirin 75 mg once daily* - While antiplatelets have a role in some protocols, **aspirin alone** provides insufficient protection against VTE following high-risk procedures like hip fracture surgery. - Current guidelines favor **anticoagulants** over antiplatelets for chemical prophylaxis in the immediate post-operative period for orthopedic trauma. *Mechanical prophylaxis only with intermittent pneumatic compression* - **Mechanical prophylaxis** is generally used as an adjunct to pharmacological methods rather than a standalone treatment for high-risk hip surgeries. - It is only used as **monotherapy** if there is an absolute contraindication to all forms of pharmacological anticoagulation, which is not stated here.
Question 159: A 43-year-old woman presents with a 12-week history of lower back pain radiating to the lateral aspect of her right thigh and leg. She describes tingling over the dorsum of her foot and reports difficulty with foot dorsiflexion when walking. Examination reveals weakness of right ankle dorsiflexion (4/5 power), diminished sensation over the first web space, and a positive straight leg raise at 40 degrees on the right. What is the most likely nerve root affected?
- A. L3
- B. L4
- C. L5 (Correct Answer)
- D. S1
- E. S2
Explanation: ***L5*** - The **L5 nerve root** is responsible for sensory innervation of the **first web space** and the **dorsum of the foot**, which matches the patient's tingling and sensory deficit. - Weakness in **ankle dorsiflexion** and difficulty with **foot dorsiflexion** when walking are classic motor signs of **L5 radiculopathy**, typically caused by an **L4-L5 disc herniation**. *L3* - **L3 radiculopathy** typically presents with pain and sensory loss over the **anterior thigh** and the medial aspect of the knee. - It is associated with weakness in **hip flexion** and **knee extension**, along with a potentially diminished **patellar reflex**. *L4* - The **L4 nerve root** provides sensation to the **medial malleolus** and medial leg rather than the first web space. - While it contributes to ankle dorsiflexion, a deficit here usually presents with a loss of the **knee-jerk reflex**, which is not mentioned. *S1* - **S1 nerve root** compression typically causes weakness in **plantarflexion** and a loss of the **calcaneal (ankle) reflex**. - Sensory loss in S1 radiculopathy is localized to the **lateral foot** and the small toe, which contradicts this patient's symptoms. *S2* - **S2 radiculopathy** is rare and generally results in sensory deficits over the **posterior thigh** or the popliteal fossa. - It does not involve dorsiflexion of the foot and is more often associated with **cauda equina syndrome** if presenting with bowel/bladder dysfunction.
Question 160: A 68-year-old man undergoes dynamic hip screw fixation for an intertrochanteric femur fracture. Post-operatively, the tip-apex distance (TAD) is measured on the AP and lateral radiographs. What is the maximum acceptable tip-apex distance to minimize the risk of screw cut-out?
- A. 15 mm
- B. 20 mm
- C. 25 mm (Correct Answer)
- D. 30 mm
- E. 35 mm
Explanation: ***25 mm*** - The **Tip-Apex Distance (TAD)** is a critical measurement for predicting **lag screw cut-out** in intertrochanteric femur fractures. - A TAD of **25 mm or less** is widely accepted as the maximum acceptable distance to minimize the risk of screw cut-out, according to the **Baumgaertner criteria**. *15 mm* - While a TAD of 15 mm indicates an **excellent screw position** and provides high mechanical stability, it is not the *maximum acceptable* limit but rather a highly optimal target. - This value is well within the safe zone, significantly reducing the risk of **fixation failure**. *20 mm* - A TAD of 20 mm also represents a **safe and good screw placement**, offering a low risk of cut-out. - Like 15 mm, it is not the *maximum acceptable* limit but falls comfortably below the critical threshold of **25 mm**. *30 mm* - A TAD of **30 mm** is greater than the accepted maximum of 25 mm and significantly increases the risk of **lag screw cut-out**. - This distance suggests the screw is positioned too far from the **subchondral bone** of the femoral head, leading to less stable fixation. *35 mm* - A TAD of **35 mm** represents a very poor and unsafe screw position, indicative of **suboptimal surgical technique**. - Such a high TAD is associated with a substantially increased risk of **fixation failure** and other post-operative complications.
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