Orthopaedics & MSK — MCQs
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A 73-year-old woman sustains a subcapital neck of femur fracture with minimal displacement (Garden II). She is an active independent woman who plays golf twice weekly and lives alone. She has well-controlled hypertension and type 2 diabetes. Bone mineral density T-score is -2.8 at the femoral neck. The orthopaedic team discusses fixation versus arthroplasty options. Which factor most strongly supports proceeding with internal fixation with cannulated screws rather than arthroplasty?
A 67-year-old woman presents to the Emergency Department with acute onset severe lower back pain and bilateral leg weakness that developed over 6 hours. She has metastatic lung cancer currently receiving palliative chemotherapy. On examination, power is 2/5 bilaterally in all muscle groups of both legs, with a sensory level at T10, absent ankle reflexes, and reduced perianal sensation. MRI demonstrates cord compression at T9-T10 with significant canal compromise. Despite immediate high-dose dexamethasone, her neurology deteriorates to complete paraplegia over the next 4 hours. What is the most appropriate definitive management at this stage?
A 55-year-old man presents with a 6-month history of lower back pain and progressive bilateral leg weakness. He reports a 12 kg weight loss and has noticed his urine has become very dark. Blood tests show: Hb 96 g/L, corrected calcium 3.2 mmol/L, creatinine 145 μmol/L, ESR 85 mm/hr, and total protein 95 g/L. Serum protein electrophoresis shows a monoclonal band. Lumbar spine radiographs demonstrate multiple lytic lesions. What is the most likely diagnosis?
A 72-year-old woman sustains a reverse oblique intertrochanteric femur fracture. Pre-injury she was independently mobile with one stick. The fracture line extends from proximolateral to distomedial and is highly unstable. Which fixation method provides the most biomechanically stable construct for this fracture pattern?
A 65-year-old woman with metastatic breast cancer presents with a 6-week history of progressively worsening thoracic back pain that is constant, unrelieved by rest, and worse at night. Over the past 48 hours, she has developed bilateral leg weakness and difficulty walking. On examination, power is 3/5 in both legs with a sensory level at T8 and brisk reflexes with upgoing plantars. Perianal sensation is intact. What is the most appropriate immediate management?
A 58-year-old woman presents to her GP with a 4-month history of lower back pain, night sweats, and unintentional weight loss of 8 kg. She emigrated from South Asia 15 years ago. On examination, there is tenderness over the lower thoracic spine and a palpable fluctuant mass in the right groin. ESR is 95 mm/hr and chest radiograph shows apical shadowing. What is the most appropriate next investigation to confirm the diagnosis?
An 83-year-old woman presents with a subcapital neck of femur fracture following a fall. She has advanced Alzheimer's dementia (Abbreviated Mental Test Score 2/10), is doubly incontinent, and was bed-bound prior to the injury. She lives in a nursing home and requires total care for all activities of daily living. Her medical history includes ischaemic heart disease, chronic kidney disease stage 4, and previous stroke with residual hemiparesis. What is the most appropriate initial management approach?
A 70-year-old man sustains a displaced intracapsular neck of femur fracture. He has a past medical history of chronic obstructive pulmonary disease, type 2 diabetes mellitus, and previous myocardial infarction 8 months ago with a drug-eluting stent insertion. He is on dual antiplatelet therapy with aspirin and clopidogrel. The orthopaedic team plans a cemented hemiarthroplasty. What is the most appropriate peri-operative management of his antiplatelet therapy?
A 52-year-old woman presents with a 3-month history of lower back pain radiating to both buttocks and posterior thighs. She reports that the pain is worse when walking uphill or standing and is relieved when sitting or leaning forward on a shopping trolley. Neurological examination reveals normal power, sensation, and reflexes in both lower limbs. What is the most likely underlying pathological mechanism?
A 77-year-old woman undergoes cannulated screw fixation for an undisplaced Garden II subcapital neck of femur fracture. Post-operatively, she develops sudden onset severe right-sided chest pain, dyspnoea, and hypotension 18 hours after surgery. She becomes acutely confused and her oxygen saturations drop to 84% on room air. An ECG shows sinus tachycardia and right bundle branch block. What is the most likely diagnosis?
Orthopaedics & MSK UK Medical PG Practice Questions and MCQs
Question 131: A 73-year-old woman sustains a subcapital neck of femur fracture with minimal displacement (Garden II). She is an active independent woman who plays golf twice weekly and lives alone. She has well-controlled hypertension and type 2 diabetes. Bone mineral density T-score is -2.8 at the femoral neck. The orthopaedic team discusses fixation versus arthroplasty options. Which factor most strongly supports proceeding with internal fixation with cannulated screws rather than arthroplasty?
- A. The patient's good pre-injury functional status and activity level
- B. The undisplaced nature of the fracture reduces avascular necrosis risk (Correct Answer)
- C. Her age of 73 years is below the threshold for primary arthroplasty
- D. Presence of osteoporosis improves screw purchase in cancellous bone
- E. Type 2 diabetes reduces prosthetic joint infection risk
Explanation: ***The undisplaced nature of the fracture reduces avascular necrosis risk***- In **Garden I and II** (undisplaced) fractures, the **retinacular blood supply** to the femoral head is largely preserved, making **internal fixation** a viable option with lower risk of failure.- Preserving the native anatomy through fixation is generally preferred for **undisplaced fractures** regardless of age, as the risks of **avascular necrosis (AVN)** and **non-union** are significantly lower than in displaced fractures.*The patient's good pre-injury functional status and activity level*- High activity levels often favor **arthroplasty** (especially **Total Hip Replacement**) in active elderly patients, as it allows for immediate weight-bearing and avoids the risk of **fixation failure** or reoperation.- While good functional status is crucial for surgical eligibility, it doesn't provide a biological rationale for choosing **internal fixation** over **arthroplasty**; rather, it often argues for arthroplasty for quicker rehabilitation.*Her age of 73 years is below the threshold for primary arthroplasty*- There is no strict **age threshold** for arthroplasty; in fact, **primary arthroplasty** (hemi or total) is generally recommended for most elderly patients (e.g., >65 years) with **displaced** neck of femur fractures.- The decision for arthroplasty versus fixation is primarily based on the **fracture displacement** (Garden classification) and the patient's physiological age and comorbidities, not a chronological age cutoff.*Presence of osteoporosis improves screw purchase in cancellous bone*- **Osteoporosis** (T-score -2.8) signifies **reduced bone density** and weakens bone quality, which directly **impairs screw purchase** and increases the risk of **hardware cutout** or implant failure.- Poor bone mineral density is a relative **contraindication** to internal fixation, as the osteoporotic bone may not provide sufficient **stability** for the implants, leading to higher rates of non-union or reoperation.*Type 2 diabetes reduces prosthetic joint infection risk*- **Type 2 diabetes mellitus** is a well-established independent **risk factor** that significantly **increases** the risk of **prosthetic joint infection (PJI)** and impairs wound healing.- Uncontrolled or even well-controlled diabetes introduces systemic challenges that make any surgical intervention, especially arthroplasty, potentially more complicated, making this statement incorrect.
Question 132: A 67-year-old woman presents to the Emergency Department with acute onset severe lower back pain and bilateral leg weakness that developed over 6 hours. She has metastatic lung cancer currently receiving palliative chemotherapy. On examination, power is 2/5 bilaterally in all muscle groups of both legs, with a sensory level at T10, absent ankle reflexes, and reduced perianal sensation. MRI demonstrates cord compression at T9-T10 with significant canal compromise. Despite immediate high-dose dexamethasone, her neurology deteriorates to complete paraplegia over the next 4 hours. What is the most appropriate definitive management at this stage?
- A. Emergency surgical decompression and stabilisation within 6 hours of presentation
- B. Emergency radiotherapy to the affected spinal segment within 24 hours (Correct Answer)
- C. Continue high-dose corticosteroids and reassess neurology in 48 hours
- D. Palliative care approach with analgesia and supportive measures only
- E. Intrathecal chemotherapy via lumbar puncture
Explanation: ***Emergency radiotherapy to the affected spinal segment within 24 hours*** - In cases of **Metastatic Spinal Cord Compression (MSCC)** with rapid progression to **complete paraplegia**, especially in patients with advanced systemic disease (e.g., metastatic lung cancer on palliative chemotherapy), **radiotherapy** is the most appropriate definitive management. - While full functional recovery is unlikely after complete paralysis, urgent radiotherapy helps to **control local tumor growth**, provide **pain relief**, and prevent the sensory level from ascending, thereby improving quality of life. *Emergency surgical decompression and stabilisation within 6 hours of presentation* - Surgical decompression is generally favored for **ambulatory patients**, those with rapidly progressive neurological deficits who are **neurologically intact or only partially compromised**, and those with good performance status and longer life expectancy. - For a patient with **complete paraplegia** and advanced metastatic disease, the significant risks and invasiveness of major spinal surgery often outweigh the very low likelihood of functional recovery, making it less appropriate than radiotherapy. *Continue high-dose corticosteroids and reassess neurology in 48 hours* - **High-dose dexamethasone** is a crucial initial measure to reduce **peritumoral edema** and provide temporary relief in MSCC, but it is an **adjunctive treatment** and not a definitive therapy for mechanical cord compression. - Waiting 48 hours for reassessment without providing a definitive local treatment (such as radiotherapy or surgery) risks further **irreversible spinal cord damage** due to ongoing compression and ischemia. *Palliative care approach with analgesia and supportive measures only* - While the patient is receiving palliative chemotherapy, **MSCC is an oncological emergency** that still warrants active intervention to manage symptoms and prevent further complications, even if functional recovery is limited. - A purely supportive approach may lead to **ascension of the sensory level**, potentially causing autonomic dysfunction, respiratory compromise, and increased suffering that could be mitigated by targeted treatment like radiotherapy. *Intrathecal chemotherapy via lumbar puncture* - **Intrathecal chemotherapy** is primarily indicated for **leptomeningeal carcinomatosis**, which involves cancer cells spreading within the cerebrospinal fluid and meninges. - This patient has **extradural cord compression** from a solid tumor mass, not leptomeningeal disease, and a lumbar puncture is generally **contraindicated** in the presence of an obstructive spinal mass due to the risk of neurological deterioration or spinal herniation.
Question 133: A 55-year-old man presents with a 6-month history of lower back pain and progressive bilateral leg weakness. He reports a 12 kg weight loss and has noticed his urine has become very dark. Blood tests show: Hb 96 g/L, corrected calcium 3.2 mmol/L, creatinine 145 μmol/L, ESR 85 mm/hr, and total protein 95 g/L. Serum protein electrophoresis shows a monoclonal band. Lumbar spine radiographs demonstrate multiple lytic lesions. What is the most likely diagnosis?
- A. Metastatic prostate carcinoma with bony metastases
- B. Multiple myeloma with vertebral involvement (Correct Answer)
- C. Primary hyperparathyroidism with brown tumours
- D. Spinal tuberculosis with vertebral destruction
- E. Waldenstrom's macroglobulinaemia with bone involvement
Explanation: ***Multiple myeloma with vertebral involvement***- The constellation of **hypercalcaemia**, **renal impairment**, **anaemia**, and **lytic bone lesions** (the **CRAB criteria**), combined with a **monoclonal band** on serum protein electrophoresis and markedly elevated **ESR**, is highly diagnostic of **Multiple Myeloma**.- The progressive **bilateral leg weakness** and **lower back pain** are consistent with vertebral involvement and potential spinal cord compression or nerve root impingement from the lytic lesions.*Metastatic prostate carcinoma with bony metastases*- **Prostate carcinoma** bony metastases are typically **osteoblastic (sclerotic)** on imaging, in contrast to the **lytic lesions** seen in this patient.- This diagnosis would not explain the presence of a **monoclonal band** on serum protein electrophoresis or the significantly elevated total protein.*Primary hyperparathyroidism with brown tumours*- While **primary hyperparathyroidism** causes **hypercalcaemia** and can lead to bone lesions (brown tumors), it does not explain the pronounced **anaemia**, significantly elevated **ESR**, or the crucial finding of a **monoclonal band**.- Brown tumors are typically associated with very high **parathyroid hormone (PTH)** levels and are distinct from widespread lytic lesions.*Spinal tuberculosis with vertebral destruction*- **Spinal tuberculosis** (Pott's disease) involves **vertebral destruction** but usually presents with **disc space narrowing**, kyphosis, and abscess formation, which differs from the described **multiple lytic lesions**.- This condition does not account for the **monoclonal gammopathy**, significant **hypercalcaemia**, or the pattern of systemic features observed.*Waldenstrom's macroglobulinaemia with bone involvement*- **Waldenstrom's macroglobulinaemia** is characterized by an **IgM monoclonal gammopathy** and can cause anaemia and elevated ESR, but it **rarely causes lytic bone lesions** or significant **hypercalcaemia**.- Clinical features typically include **hyperviscosity syndrome**, lymphadenopathy, and hepatosplenomegaly, which are not described here.
Question 134: A 72-year-old woman sustains a reverse oblique intertrochanteric femur fracture. Pre-injury she was independently mobile with one stick. The fracture line extends from proximolateral to distomedial and is highly unstable. Which fixation method provides the most biomechanically stable construct for this fracture pattern?
- A. Sliding hip screw with derotation screw
- B. Multiple cannulated screws in parallel configuration
- C. Cephalomedullary nail with proximal and distal locking screws (Correct Answer)
- D. Cemented hemiarthroplasty with long stem
- E. External fixation with pins in iliac crest and proximal femur
Explanation: ***Cephalomedullary nail with proximal and distal locking screws*** - A **reverse oblique intertrochanteric fracture** is highly unstable because the fracture line parallels the pull of the **adductor muscles**, leading to medialization of the distal fragment. - The intramedullary position of a **cephalomedullary nail** provides a shorter **lever arm** and acts as a load-sharing device, effectively preventing the **medial displacement** and varus collapse common in this pattern. *Sliding hip screw with derotation screw* - In reverse oblique patterns, the **sliding hip screw (SHS)** is contraindicated because the fracture line is parallel to the screw, which can lead to catastrophic **medialization of the shaft** and hardware failure. - The SHS relies on a lateral cortex for a **buttress**, which is absent or compromised in this specific fracture configuration. *Multiple cannulated screws in parallel configuration* - This fixation method lacks the required **biostatic strength** and structural stability to support the heavy loads of an **extracapsular fracture**. - Parallel screws are primarily indicated for **nondisplaced intracapsular femoral neck fractures**, not unstable intertrochanteric patterns. *Cemented hemiarthroplasty with long stem* - While used for severely comminuted fractures in the very elderly, **internal fixation** is preferred for extracapsular fractures to preserve the native joint in a patient who was **independently mobile**. - Hemiarthroplasty is generally reserved for **intracapsular fractures** or as a salvage procedure after failed fixation, rather than primary treatment for this pattern. *External fixation with pins in iliac crest and proximal femur* - External fixation is rarely used for definitive femur fracture management and is typically reserved for **damage control orthopaedics** in polytrauma patients. - It provides poor **biomechanical stability** for weight-bearing and carries a high risk of **pin-site infection** and non-union in this age group.
Question 135: A 65-year-old woman with metastatic breast cancer presents with a 6-week history of progressively worsening thoracic back pain that is constant, unrelieved by rest, and worse at night. Over the past 48 hours, she has developed bilateral leg weakness and difficulty walking. On examination, power is 3/5 in both legs with a sensory level at T8 and brisk reflexes with upgoing plantars. Perianal sensation is intact. What is the most appropriate immediate management?
- A. Commence oral dexamethasone 16mg daily and arrange routine MRI spine within 1 week
- B. Give intravenous dexamethasone 16mg immediately and arrange urgent MRI whole spine within 24 hours (Correct Answer)
- C. Arrange urgent CT spine and commence chemotherapy for metastatic disease
- D. Refer to oncology for urgent radiotherapy planning without imaging
- E. Commence analgesia and arrange palliative care assessment
Explanation: ***Give intravenous dexamethasone 16mg immediately and arrange urgent MRI whole spine within 24 hours***- This patient presents with signs of **metastatic spinal cord compression (MSCC)**, an oncological emergency requiring immediate **high-dose corticosteroids** to reduce peritumoral edema and preserve neurological function.- An **urgent MRI of the whole spine** within 24 hours is essential to confirm the level of compression, rule out multi-level disease, and guide definitive surgical or radiation therapy.*Commence oral dexamethasone 16mg daily and arrange routine MRI spine within 1 week*- Delaying the **MRI spine** for up to a week is inappropriate for suspected MSCC, as irreversible **neurological deficits** like paralysis can develop rapidly.- While oral dexamethasone is an option, the term "**routine**" MRI fails to address the critical urgency required for imaging in a patient with acute neurological compromise.*Arrange urgent CT spine and commence chemotherapy for metastatic disease*- **MRI** is the superior imaging modality for evaluating the **spinal cord** and soft tissue lesions causing compression, whereas **CT spine** has limited ability to visualize the cord directly.- **Chemotherapy** is generally not the immediate treatment for acute cord compression; prompt mechanical decompression (surgery) or radiotherapy is needed to relieve pressure on the cord.*Refer to oncology for urgent radiotherapy planning without imaging*- Performing **radiotherapy** without prior **MRI imaging** is inappropriate and potentially harmful, as it prevents precise localization of the compression and assessment for surgical candidacy.- **Imaging** is crucial to determine the extent of disease, stability of the spine, and to differentiate between cases that require **surgical decompression** versus those best managed by radiotherapy alone.*Commence analgesia and arrange palliative care assessment*- While **pain management** is important, this approach overlooks the **neurological emergency** of MSCC, which requires immediate, aggressive intervention to preserve function.- A patient with **metastatic breast cancer** experiencing acute spinal cord compression has a potentially reversible cause of neurological decline, making palliative care alone premature.
Question 136: A 58-year-old woman presents to her GP with a 4-month history of lower back pain, night sweats, and unintentional weight loss of 8 kg. She emigrated from South Asia 15 years ago. On examination, there is tenderness over the lower thoracic spine and a palpable fluctuant mass in the right groin. ESR is 95 mm/hr and chest radiograph shows apical shadowing. What is the most appropriate next investigation to confirm the diagnosis?
- A. Whole-body bone scan with technetium-99m
- B. MRI spine with contrast (Correct Answer)
- C. CT-guided biopsy of vertebral body with microbiological culture
- D. Serum protein electrophoresis and Bence Jones protein
- E. Fine needle aspiration of the groin mass
Explanation: ***MRI spine with contrast*** - **MRI** is the gold standard imaging modality for diagnosing **spinal tuberculosis (Pott's disease)** as it identifies vertebral destruction, **disc space narrowing**, and the extent of soft tissue involvement. - It is essential to visualize the **psoas abscess** tracking to the groin and to assess for any **spinal cord compression** that may necessitate urgent surgical intervention. *Whole-body bone scan with technetium-99m* - This investigation is sensitive for increased bone turnover, such as **metastatic disease**, but lacks the specificity required to diagnose **spinal TB**. - It cannot provide detailed information regarding **soft tissue collections** or paraspinal involvement, which are hallmark features of this presentation. *CT-guided biopsy of vertebral body with microbiological culture* - While this provides the definitive **microbiological gold standard** diagnosis, imaging must be performed first to guide the biopsy site and map the disease extent. - Obtaining tissue is critical for **drug sensitivity testing**, but it should follow the diagnostic confirmation and anatomical mapping provided by **MRI**. *Serum protein electrophoresis and Bence Jones protein* - These tests are used to screen for **Multiple Myeloma**, which can cause back pain and weight loss, but do not explain the **groin mass** or **apical shadowing**. - The clinical context of being an immigrant from a TB-endemic region and having **night sweats** makes an infectious etiology much more likely than a plasma cell dyscrasia. *Fine needle aspiration of the groin mass* - Although aspiration of the **psoas abscess** (cold abscess) may yield pus for **AFB staining** and culture, it does not allow for assessment of the spinal stability. - Relying solely on a groin sample would miss critical information regarding the **neurological risk** and vertebral destruction at the thoracic level.
Question 137: An 83-year-old woman presents with a subcapital neck of femur fracture following a fall. She has advanced Alzheimer's dementia (Abbreviated Mental Test Score 2/10), is doubly incontinent, and was bed-bound prior to the injury. She lives in a nursing home and requires total care for all activities of daily living. Her medical history includes ischaemic heart disease, chronic kidney disease stage 4, and previous stroke with residual hemiparesis. What is the most appropriate initial management approach?
- A. Cemented total hip replacement to allow immediate weight-bearing
- B. Uncemented hemiarthroplasty with post-operative protected weight-bearing
- C. Non-operative management with analgesia and early mobilisation as tolerated (Correct Answer)
- D. Dynamic hip screw fixation with bone grafting
- E. Cannulated screw fixation under regional anaesthesia
Explanation: ***Non-operative management with analgesia and early mobilisation as tolerated***- In patients who were **bed-bound before the injury** with **advanced dementia** (AMTS 2/10) and multiple **high-risk comorbidities** (IHD, CKD stage 4, stroke), surgery offers no functional benefit and carries significant risks.- The primary focus shifts to **palliative care**, ensuring **effective pain relief** and comfortable positioning, rather than attempting to restore ambulation. *Cemented total hip replacement to allow immediate weight-bearing*- This major procedure is typically reserved for **ambulatory patients** with a reasonable life expectancy who can benefit from restoration of function.- It is unsuitable for a bed-bound patient with **severe cognitive impairment** and significant **cardiac and renal comorbidities**, as the risks outweigh any potential benefit. *Uncemented hemiarthroplasty with post-operative protected weight-bearing*- While hemiarthroplasty is common for displaced neck of femur fractures in the elderly, **uncemented implants** are generally avoided in this population due to a higher risk of **periprosthetic fractures**.- The patient's **pre-existing bed-bound status** means protected weight-bearing is irrelevant, and the high surgical risks remain a contraindication. *Dynamic hip screw fixation with bone grafting*- **Dynamic hip screws (DHS)** are specifically designed for **extracapsular fractures**, such as intertrochanteric fractures, not the **intracapsular subcapital fracture** described.- **Bone grafting** is an unnecessary and invasive addition, especially in a frail, elderly patient with **poor baseline function** and multiple health issues. *Cannulated screw fixation under regional anaesthesia*- **Cannulated screw fixation** is primarily indicated for **undisplaced femoral neck fractures** or in younger, more active patients to preserve the femoral head.- For a **displaced subcapital fracture** in an 83-year-old, there's a high risk of **avascular necrosis** and non-union, and the procedure would not improve her functional status.
Question 138: A 70-year-old man sustains a displaced intracapsular neck of femur fracture. He has a past medical history of chronic obstructive pulmonary disease, type 2 diabetes mellitus, and previous myocardial infarction 8 months ago with a drug-eluting stent insertion. He is on dual antiplatelet therapy with aspirin and clopidogrel. The orthopaedic team plans a cemented hemiarthroplasty. What is the most appropriate peri-operative management of his antiplatelet therapy?
- A. Continue both aspirin and clopidogrel throughout the peri-operative period
- B. Stop both aspirin and clopidogrel 7 days before surgery and restart 24 hours post-operatively
- C. Continue aspirin and stop clopidogrel 7 days before surgery (Correct Answer)
- D. Stop clopidogrel 5 days before surgery and continue aspirin throughout
- E. Stop both agents and bridge with intravenous heparin peri-operatively
Explanation: ***Continue aspirin and stop clopidogrel 7 days before surgery*** - For a patient with a **drug-eluting stent** placed within the last year (8 months ago), **aspirin** should be continued peri-operatively to mitigate the high risk of **stent thrombosis** and **acute coronary events**. - **Clopidogrel** is an irreversible P2Y12 inhibitor that significantly increases **peri-operative bleeding** risk during major surgery; it should ideally be stopped **7 days** prior to allow for new platelet turnover. *Continue both aspirin and clopidogrel throughout the peri-operative period* - Continuing **dual antiplatelet therapy (DAPT)** during a cemented hemiarthroplasty carries an unacceptably high risk of **uncontrolled surgical hemorrhage** and potential need for transfusions. - While DAPT is critical for preventing stent-related events, the acute surgical risk outweighs the benefit of continuing clopidogrel in this context. *Stop both aspirin and clopidogrel 7 days before surgery and restart 24 hours post-operatively* - Completely stopping both agents creates a dangerously high-risk window for **acute myocardial infarction** or **stent thrombosis**, especially given the recent **drug-eluting stent**. - **Aspirin monotherapy** is considered the standard baseline protection that should not be interrupted for this type of orthopedic surgery in patients with cardiovascular risk. *Stop clopidogrel 5 days before surgery and continue aspirin throughout* - While some newer guidelines may consider a **5-day** hold for clopidogrel in certain situations, a **7-day** window is the more traditionally accepted and safer period to ensure maximal platelet recovery for major orthopedic surgery. - The longer washout period of 7 days offers a greater margin of safety against **significant surgical bleeding** for an irreversible antiplatelet agent like clopidogrel. *Stop both agents and bridge with intravenous heparin peri-operatively* - **Heparin bridging** is typically employed for patients on **oral anticoagulants** (e.g., warfarin) who require temporary interruption, not for **antiplatelet agents**. - Heparin's mechanism of action (anticoagulation) does not provide the specific **antiplatelet protection** needed to prevent **stent thrombosis**, which is addressed by aspirin.
Question 139: A 52-year-old woman presents with a 3-month history of lower back pain radiating to both buttocks and posterior thighs. She reports that the pain is worse when walking uphill or standing and is relieved when sitting or leaning forward on a shopping trolley. Neurological examination reveals normal power, sensation, and reflexes in both lower limbs. What is the most likely underlying pathological mechanism?
- A. Lumbar disc prolapse causing nerve root compression
- B. Narrowing of the spinal canal causing neurogenic claudication (Correct Answer)
- C. Spondylolisthesis causing mechanical instability
- D. Facet joint osteoarthritis causing referred pain
- E. Sacroiliac joint inflammation causing bilateral radiculopathy
Explanation: ***Narrowing of the spinal canal causing neurogenic claudication*** - The patient exhibits the classic **'shopping trolley sign'**, where leaning forward (spinal flexion) increases the **spinal canal diameter**, providing symptom relief. - **Neurogenic claudication** typically presents with bilateral leg pain triggered by walking or standing (spinal extension), which further narrows the already stenotic lumbar canal. *Lumbar disc prolapse causing nerve root compression* - Usually presents as **acute unilateral radiculopathy** (sciatica) rather than bilateral symptoms triggered by specific postures like standing. - Often associated with positive **straight leg raise** tests and specific focal **neurological deficits**, which are absent in this case. *Spondylolisthesis causing mechanical instability* - While it can lead to stenosis, primary mechanical instability typically causes **localized back pain** that worsens with specific movements or lifting transitions. - It often presents with a palpable **'step-off'** deformity on examination and does not always follow the classic flexion-relief pattern of central stenosis. *Facet joint osteoarthritis causing referred pain* - Typically causes **localized stiffness** and pain that is worse with **spinal extension** and rotation, but it does not usually cause radiating claudication symptoms. - Referred pain from facet joints generally does not follow a **dermatomal distribution** to the posterior thighs and lacks the 'shopping trolley' relief pattern. *Sacroiliac joint inflammation causing bilateral radiculopathy* - **Sacroiliitis** generally causes pain over the **buttocks and groin** that is worse with sitting and improved by walking, which is the opposite of this patient's presentation. - Inflammation of these joints does not cause true **radiculopathy** or neurogenic claudication symptoms localized to the spinal canal.
Question 140: A 77-year-old woman undergoes cannulated screw fixation for an undisplaced Garden II subcapital neck of femur fracture. Post-operatively, she develops sudden onset severe right-sided chest pain, dyspnoea, and hypotension 18 hours after surgery. She becomes acutely confused and her oxygen saturations drop to 84% on room air. An ECG shows sinus tachycardia and right bundle branch block. What is the most likely diagnosis?
- A. Fat embolism syndrome (Correct Answer)
- B. Acute myocardial infarction
- C. Bone cement implantation syndrome
- D. Pulmonary embolism
- E. Hospital-acquired pneumonia
Explanation: ***Fat embolism syndrome*** - Occurs classically 24-72 hours post-orthopaedic surgery involving **long bone fractures**, presenting with a **triad** of **respiratory distress**, **neurological dysfunction** (confusion), and sometimes a **petechial rash**.- The sudden onset of severe **dyspnoea**, **hypotension**, **hypoxia** (84% O2 sats), and **acute confusion** 18 hours after femur fracture fixation is highly characteristic of fat embolism. *Acute myocardial infarction*- While it can cause chest pain and hypotension, an ECG would typically show **ST-segment changes** or T-wave inversions rather than a new **Right Bundle Branch Block** as the primary cardiac finding.- **Acute confusion** is a less prominent or primary symptom in AMI compared to the respiratory and neurological features seen here, especially in the context of recent orthopaedic trauma.*Bone cement implantation syndrome*- Characterized by hypoxia and hypotension occurring **intra-operatively**, specifically during the **pressurisation of cement** or prosthesis insertion.- This patient underwent **cannulated screw fixation** for an undisplaced fracture, a procedure that does **not involve bone cement**, making this diagnosis impossible.*Pulmonary embolism*- Typically presents with sudden onset **dyspnoea**, **chest pain**, and **hypotension** (as seen here), and can cause RBBB due to right heart strain.- However, the significant and sudden **neurological deterioration** (acute confusion) in combination with respiratory symptoms and timing post-long bone fracture is more indicative of **fat embolism syndrome**.*Hospital-acquired pneumonia*- Usually presents with **fever**, productive cough, and **basal crackles** rather than sudden onset severe chest pain and hypotension.- Development within **18 hours** is too rapid for typical HAP, which usually requires at least 48 hours of hospitalisation to manifest.
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