Orthopaedics & MSK — MCQs
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A 73-year-old man undergoes a dynamic hip screw for an intertrochanteric neck of femur fracture. Post-operatively on day 2, he develops sudden onset shortness of breath, confusion, and petechial rash over his chest and conjunctiva. His oxygen saturation is 88% on room air. Blood results show thrombocytopenia and hypocalcaemia. What is the most likely diagnosis?
A 44-year-old woman presents with chronic lower back pain and is found to have a large central disc prolapse at L4/L5 on MRI. She has mild bilateral leg pain but no motor weakness, normal reflexes, and normal bladder function. She has failed 8 weeks of conservative management including physiotherapy and analgesia. What is the most appropriate next step in management?
A 58-year-old man with a 20-year history of ankylosing spondylitis sustains a neck of femur fracture following minimal trauma. Radiographs show a transverse extracapsular fracture through osteoporotic bone. His bone mineral density T-score is -3.2. In addition to surgical fixation, which long-term management strategy is most important to reduce future fracture risk?
Which classification system for intracapsular neck of femur fractures is based on the degree of displacement and comminution visible on anteroposterior and lateral radiographs, and correlates with risk of avascular necrosis?
A 67-year-old woman with metastatic breast cancer presents with a 4-week history of progressively worsening mid-thoracic back pain, worse at night and not relieved by analgesia. She now reports difficulty walking and numbness in both legs. On examination, she has a sensory level at T8, bilateral lower limb weakness (power 3/5), and brisk reflexes with upgoing plantars. What is the most appropriate immediate investigation?
A 29-year-old professional rugby player presents with acute lower back pain following a tackle 3 days ago. He describes sharp pain radiating down his right leg to the lateral aspect of his foot. On examination, he has weakness of foot eversion, reduced sensation over the dorsum of the foot, and an absent ankle reflex. Straight leg raise is positive at 40 degrees on the right. Which nerve root is most likely affected?
An 81-year-old woman presents 48 hours after a fall with a displaced intracapsular neck of femur fracture. She has a history of Parkinson's disease and takes levodopa. Her pre-admission mobility was limited to indoor walking with a frame. Which surgical intervention offers the best balance of functional outcome and surgical morbidity?
A 43-year-old woman presents with a 6-month history of lower back pain radiating to both legs, worse on standing and walking, relieved by sitting or leaning forward. She describes difficulty walking up hills but can cycle without problems. Neurological examination reveals preserved reflexes and no sensory deficit. What is the most likely diagnosis?
A 75-year-old man undergoes internal fixation with cannulated screws for an undisplaced intracapsular neck of femur fracture. Six months post-operatively, he develops increasing hip pain and difficulty mobilising. Radiographs show segmental collapse of the femoral head with a crescent sign. What is the underlying pathophysiological mechanism?
A 52-year-old man with a history of chronic lower back pain presents with new onset bilateral leg weakness, saddle anaesthesia, and urinary retention over the past 8 hours. On examination, he has reduced anal tone and bilateral absent ankle reflexes. What is the most appropriate immediate management?
Orthopaedics & MSK UK Medical PG Practice Questions and MCQs
Question 211: A 73-year-old man undergoes a dynamic hip screw for an intertrochanteric neck of femur fracture. Post-operatively on day 2, he develops sudden onset shortness of breath, confusion, and petechial rash over his chest and conjunctiva. His oxygen saturation is 88% on room air. Blood results show thrombocytopenia and hypocalcaemia. What is the most likely diagnosis?
- A. Pulmonary embolism
- B. Fat embolism syndrome (Correct Answer)
- C. Bone cement implantation syndrome
- D. Acute respiratory distress syndrome
- E. Allergic reaction to surgical materials
Explanation: ***Fat embolism syndrome*** - This diagnosis is characterized by the classic triad of **respiratory distress** (shortness of breath, low SpO2), **neurological impairment** (confusion), and a **petechial rash** over the chest and conjunctiva, typically occurring 24-72 hours after long bone fracture surgery.- Biochemical markers like **thrombocytopenia** (due to platelet aggregation and consumption) and **hypocalcaemia** (from fatty acids binding calcium) are classic laboratory findings in this syndrome.*Pulmonary embolism* - While it causes sudden **shortness of breath** and hypoxia, a **petechial rash** and **thrombocytopenia** are not typical features of a standard pulmonary embolism.- It usually presents later in the post-operative period unless there is a pre-existing deep vein thrombosis.*Bone cement implantation syndrome* - This condition occurs **intraoperatively** or immediately post-operatively, during the insertion of bone cement, leading to hypotension, hypoxia, and cardiac arrhythmias.- The patient underwent a **dynamic hip screw (DHS)**, which is an **uncemented** fixation, and symptoms appeared on day 2, not during surgery.*Acute respiratory distress syndrome* - ARDS is characterized by severe hypoxemia and **bilateral pulmonary infiltrates** on imaging, but it does not primarily account for the distinctive **petechial rash** or **neurological symptoms**.- While ARDS can be a consequence of severe fat embolism, it doesn't encompass the full systemic and dermatological presentation seen in this case.*Allergic reaction to surgical materials* - Anaphylaxis or severe allergy would typically manifest with **urticaria** (hives), angioedema, or bronchospasm, usually occurring **immediately** or very shortly after exposure.- A **petechial rash**, confusion, thrombocytopenia, and hypocalcaemia are not characteristic features of an allergic reaction to surgical materials.
Question 212: A 44-year-old woman presents with chronic lower back pain and is found to have a large central disc prolapse at L4/L5 on MRI. She has mild bilateral leg pain but no motor weakness, normal reflexes, and normal bladder function. She has failed 8 weeks of conservative management including physiotherapy and analgesia. What is the most appropriate next step in management?
- A. Urgent surgical decompression
- B. Epidural steroid injection (Correct Answer)
- C. Continue conservative management for another 4 weeks
- D. Arrange nerve conduction studies
- E. Commence oral prednisolone 40mg daily
Explanation: ***Epidural steroid injection***- In patients with chronic **radicular pain** due to disc prolapse who have failed initial conservative management (at least 6 weeks), **epidural steroid injections** are a recommended next step to reduce inflammation and provide symptomatic relief.- This intervention aims to manage pain effectively without the immediate risks of surgery, often combining a **local anesthetic** with **corticosteroids**.*Urgent surgical decompression*- This is reserved for emergency presentations like **Cauda Equina Syndrome**, characterized by saddle anesthesia, bladder dysfunction, or progressive **motor weakness**, none of which this patient has.- While surgery is an option after conservative failure, "urgent" decompression is not clinically indicated for stable **radiculopathy** without neurological deficits.*Continue conservative management for another 4 weeks*- The patient has already completed **8 weeks of conservative therapy** (physiotherapy and analgesia) without success, meeting the threshold to escalate care.- Continuing the same path without intervention is unlikely to yield further benefit and delays relief for a patient with persistent **radiculopathy**.*Arrange nerve conduction studies*- **Nerve conduction studies (NCS)** are generally used to diagnose peripheral neuropathies or clarify nerve compression if the diagnosis is uncertain; here, the **MRI** has already localized the pathology.- These studies provide functional data but do not guide the immediate therapeutic management for a confirmed **disc prolapse**.*Commence oral prednisolone 40mg daily*- **Oral corticosteroids** are not standard evidence-based treatment for spinal disc prolapse and lack the efficacy of localized delivery via an epidural.- Systemic steroids carry a significant side-effect profile and do not provide the targeted anti-inflammatory benefit needed at the **nerve root**.
Question 213: A 58-year-old man with a 20-year history of ankylosing spondylitis sustains a neck of femur fracture following minimal trauma. Radiographs show a transverse extracapsular fracture through osteoporotic bone. His bone mineral density T-score is -3.2. In addition to surgical fixation, which long-term management strategy is most important to reduce future fracture risk?
- A. Increase calcium and vitamin D supplementation only
- B. Commence bisphosphonate therapy and ensure adequate calcium/vitamin D (Correct Answer)
- C. Prescribe calcitonin and arrange annual DEXA scans
- D. Start strontium ranelate and physiotherapy
- E. Prescribe raloxifene and recommend weight-bearing exercise
Explanation: ***Commence bisphosphonate therapy and ensure adequate calcium/vitamin D***- The patient has **severe osteoporosis** (T-score -3.2) and a **fragility fracture**, making **bisphosphonates** the first-line treatment to inhibit bone resorption and reduce future fracture risk.- **Calcium and vitamin D** are essential co-factors, providing the necessary minerals for bone formation and optimizing the effectiveness of anti-resorptive therapies.*Increase calcium and vitamin D supplementation only*- While necessary, **calcium and vitamin D supplementation alone** are insufficient to manage **severe osteoporosis** (T-score -3.2) and prevent further fragility fractures.- These supplements are supportive but do not directly address the underlying **osteoclastic overactivity** seen in osteoporosis, which requires more potent agents.*Prescribe calcitonin and arrange annual DEXA scans*- **Calcitonin** has a limited role in osteoporosis management, primarily for short-term pain relief in acute vertebral fractures, and is not effective for **long-term fracture prevention**.- **Annual DEXA scans** are generally not recommended as bone density changes slowly; scans every 2 years are typically sufficient to monitor treatment efficacy.*Start strontium ranelate and physiotherapy*- **Strontium ranelate** is no longer recommended as a first-line treatment for osteoporosis due to concerns about increased risk of **cardiovascular events** and **venous thromboembolism**.- **Physiotherapy** is important for maintaining mobility and function in ankylosing spondylitis but does not replace pharmacological therapy for **severe osteoporosis** and fracture prevention.*Prescribe raloxifene and recommend weight-bearing exercise*- **Raloxifene** is a selective estrogen receptor modulator (SERM) primarily indicated for **postmenopausal osteoporosis** in women and is not appropriate for male patients.- **Weight-bearing exercise** can help maintain bone density but is insufficient as a standalone treatment for established **severe osteoporosis** with a T-score of -3.2 and a history of fragility fracture.
Question 214: Which classification system for intracapsular neck of femur fractures is based on the degree of displacement and comminution visible on anteroposterior and lateral radiographs, and correlates with risk of avascular necrosis?
- A. AO/OTA classification
- B. Garden classification (Correct Answer)
- C. Pauwels classification
- D. Vancouver classification
- E. Neer classification
Explanation: ***Garden classification*** - This system classifies **intracapsular femoral neck fractures** into four stages based on the degree of **displacement** and the alignment of **medial trabeculae** visible on anteroposterior and lateral radiographs. - It is crucial for assessing the risk of **avascular necrosis (AVN)** of the femoral head, with higher Garden stages (III and IV) indicating significant displacement and a greater risk of vascular compromise. *AO/OTA classification* - This is a comprehensive, **alphanumeric system** designed for general fracture classification across all bones, used for standardizing descriptions in research and clinical practice. - While it can describe femoral neck fractures, it does not specifically focus on the **trabecular alignment** or directly correlate with **avascular necrosis risk** as precisely as the Garden system. *Pauwels classification* - This system classifies **femoral neck fractures** based on the **angle of the fracture line** relative to the horizontal plane. - Its primary utility is to assess the **mechanical stability** and predict the risk of non-union by quantifying shear forces, not primarily the degree of displacement or AVN risk. *Vancouver classification* - This classification system is specifically used for **periprosthetic femoral fractures**, which occur in the femur around or distal to an existing hip prosthesis. - It considers factors like the fracture location, the **stability of the implant**, and the quality of the host bone, entirely distinct from an *intact* femoral neck fracture. *Neer classification* - This system is exclusively used for classifying **proximal humerus fractures**, not fractures of the femoral neck. - It is based on the number of **displaced anatomical segments** (head, greater tuberosity, lesser tuberosity, shaft) and is unrelated to hip fractures.
Question 215: A 67-year-old woman with metastatic breast cancer presents with a 4-week history of progressively worsening mid-thoracic back pain, worse at night and not relieved by analgesia. She now reports difficulty walking and numbness in both legs. On examination, she has a sensory level at T8, bilateral lower limb weakness (power 3/5), and brisk reflexes with upgoing plantars. What is the most appropriate immediate investigation?
- A. Plain radiographs of thoracic spine
- B. Urgent whole spine MRI (Correct Answer)
- C. CT thoracic spine
- D. Bone scan
- E. PET-CT scan
Explanation: ***Urgent whole spine MRI***- This patient presents with signs of **metastatic spinal cord compression (MSCC)**, an oncological emergency requiring prompt diagnosis to prevent permanent neurological deficits.- **Urgent whole spine MRI** is the **gold standard** as it provides comprehensive visualization of the spinal cord, epidural space, and can identify the exact level and extent of compression, including multiple lesions.*Plain radiographs of thoracic spine*- Plain X-rays have low sensitivity for visualizing the **spinal cord** and **soft tissue compression**, which are critical in MSCC.- While they might show **vertebral collapse** or lytic lesions, a normal radiograph cannot exclude cord compression and should not delay definitive imaging.*CT thoracic spine*- CT offers superior detail of **bony structures** and potential fractures but is inferior to MRI for evaluating **spinal cord** and **epidural soft tissue compression**.- A CT of only the thoracic spine might miss **synchronous lesions** in other spinal regions, which can occur in patients with metastatic disease.*Bone scan*- Radionuclide bone scans are highly sensitive for detecting **osteoblastic metastases** but do not provide information regarding the direct compression of the **spinal cord** or thecal sac.- This investigation is primarily for staging bone involvement and cannot guide acute management of neurological compromise.*PET-CT scan*- PET-CT is an advanced imaging modality used for cancer staging and detecting **metabolically active lesions** but is not the appropriate immediate investigation for suspected spinal cord compression.- It is a lengthy procedure and lacks the necessary **spatial resolution** of an MRI to precisely evaluate direct spinal cord compromise in an emergency setting.
Question 216: A 29-year-old professional rugby player presents with acute lower back pain following a tackle 3 days ago. He describes sharp pain radiating down his right leg to the lateral aspect of his foot. On examination, he has weakness of foot eversion, reduced sensation over the dorsum of the foot, and an absent ankle reflex. Straight leg raise is positive at 40 degrees on the right. Which nerve root is most likely affected?
- A. L3
- B. L4
- C. L5
- D. S1 (Correct Answer)
- E. S2
Explanation: ***S1*** - The patient's presentation of **sharp pain radiating to the lateral aspect of the foot**, **weakness of foot eversion**, and an **absent ankle reflex** are classic signs of S1 radiculopathy. - S1 nerve root compression specifically impairs the **gastrocnemius and soleus muscles** (leading to loss of ankle reflex) and the **peroneal muscles** (causing weakness in foot eversion). *L3* - L3 radiculopathy typically involves pain and sensory changes in the **anterior thigh** and **medial knee**. - Motor weakness affects **hip flexion** and **knee extension**, often with a diminished or absent **patellar reflex**, which is not observed here. *L4* - L4 nerve root compression presents with pain and sensory loss over the **medial leg** and ankle, and weakness in **knee extension**. - The distinguishing reflex finding for L4 is a reduced or **absent patellar reflex**, contrasting with the absent ankle reflex in this case. *L5* - L5 radiculopathy primarily causes weakness in **foot dorsiflexion** and **great toe extension**, with sensory loss usually in the **first web space** and mid-dorsum of the foot. - A key differentiator is that the **ankle reflex remains intact** in L5 lesions, which contradicts the patient's absent ankle reflex. *S2* - S2 nerve root involvement is less common and typically presents with pain or sensory disturbance in the **posterior thigh** and **perianal region**. - Motor deficits are usually associated with **plantarflexion** and intrinsic foot muscles, but without the specific constellation of symptoms pointing to S1 involvement.
Question 217: An 81-year-old woman presents 48 hours after a fall with a displaced intracapsular neck of femur fracture. She has a history of Parkinson's disease and takes levodopa. Her pre-admission mobility was limited to indoor walking with a frame. Which surgical intervention offers the best balance of functional outcome and surgical morbidity?
- A. Total hip replacement
- B. Hemiarthroplasty (Correct Answer)
- C. Dynamic hip screw
- D. Proximal femoral nail
- E. Cannulated screw fixation
Explanation: ***Hemiarthroplasty*** - For elderly patients with **limited mobility** (indoor walking with a frame) and comorbidities like **Parkinson's disease**, hemiarthroplasty provides good pain relief with lower **surgical morbidity**. - It is the treatment of choice in **displaced intracapsular fractures** for low-demand patients, allowing immediate **weight-bearing** and having a lower risk of **dislocation** compared to total hip replacement, especially in patients with neuromuscular disorders. *Total hip replacement* - While offering better long-term functional results, it is generally reserved for more active patients (independent outdoors) without significant **cognitive impairment**. - This patient's limited indoor mobility and increased **neuromuscular instability** from Parkinson’s disease significantly elevate the risk of postoperative **dislocation** and poorer functional outcomes. *Dynamic hip screw* - This device is primarily indicated for **extracapsular hip fractures**, such as **intertrochanteric fractures**, rather than intracapsular ones. - In displaced intracapsular fractures, a dynamic hip screw carries a high risk of **non-union** and **avascular necrosis** due to compromised blood supply to the femoral head. *Proximal femoral nail* - This intramedullary device is indicated for **subtrochanteric fractures** or complex unstable **extracapsular fractures**. - It is not used for **intracapsular fractures**, as it does not adequately address the high risk of **femoral head osteonecrosis** inherent in these injuries. *Cannulated screw fixation* - This method is usually reserved for **undisplaced or impacted** intracapsular fractures (Garden I and II) to preserve the native femoral head. - In **displaced fractures** (Garden III and IV) in an 81-year-old, the risk of **failure of fixation** and subsequent **avascular necrosis** is unacceptably high, making arthroplasty a more appropriate solution.
Question 218: A 43-year-old woman presents with a 6-month history of lower back pain radiating to both legs, worse on standing and walking, relieved by sitting or leaning forward. She describes difficulty walking up hills but can cycle without problems. Neurological examination reveals preserved reflexes and no sensory deficit. What is the most likely diagnosis?
- A. Lumbar disc prolapse with bilateral nerve root compression
- B. Cauda equina syndrome
- C. Lumbar spinal stenosis (Correct Answer)
- D. Ankylosing spondylitis
- E. Peripheral vascular disease
Explanation: ***Lumbar spinal stenosis***- Characterized by **neurogenic claudication**, where leg pain is exacerbated by walking or standing and relieved by **spinal flexion** (sitting or leaning forward).- The ability to **cycle without problems** (the "shopping cart sign") is classic because flexion increases the cross-sectional area of the spinal canal, relieving pressure on neural elements.*Lumbar disc prolapse with bilateral nerve root compression*- Typically presents with **acute onset** radicular pain and often demonstrates **positive straight leg raise** or other nerve root tension signs.- Symptoms are usually **unilateral** or asymmetrical, and are often worsened by flexion (sitting), which is the opposite of this patient's presentation.*Cauda equina syndrome*- A surgical emergency presenting with **saddle anesthesia**, bladder or bowel dysfunction, and **decreased anal tone**.- This patient lacks the significant neurological deficits and acute **sphincter dysfunction** characteristic of this syndrome.*Ankylosing spondylitis*- Presents as **inflammatory back pain** that is typically worse at rest or in the morning and **improves with exercise**.- It primarily affects the **sacroiliac joints** and is associated with significant morning stiffness, unlike the activity-induced pain seen here.*Peripheral vascular disease*- Causes **vascular claudication**, where pain is strictly related to exertion and is relieved simply by **standing still**.- Unlike spinal stenosis, it is not affected by **spinal posture** (leaning forward) and is usually accompanied by **diminished peripheral pulses**.
Question 219: A 75-year-old man undergoes internal fixation with cannulated screws for an undisplaced intracapsular neck of femur fracture. Six months post-operatively, he develops increasing hip pain and difficulty mobilising. Radiographs show segmental collapse of the femoral head with a crescent sign. What is the underlying pathophysiological mechanism?
- A. Non-union of the fracture due to inadequate fixation
- B. Avascular necrosis of the femoral head secondary to disrupted blood supply (Correct Answer)
- C. Septic arthritis from surgical site infection
- D. Osteoarthritis secondary to altered hip biomechanics
- E. Heterotopic ossification causing restricted movement
Explanation: ***Avascular necrosis of the femoral head secondary to disrupted blood supply*** - The **crescent sign** (subchondral lucency) and **segmental collapse** of the femoral head are characteristic radiological findings for **avascular necrosis (AVN)**, typically occurring months after injury. - Intracapsular neck of femur fractures, even if undisplaced, frequently disrupt the **medial circumflex femoral artery** and its retinacular branches, leading to ischemia and eventual bone death. *Non-union of the fracture due to inadequate fixation* - This condition would typically present with persistent pain at the fracture site, possibly with visible **fracture line** on radiographs, or signs of **hardware failure** (e.g., screw loosening or cut-out). - While non-union causes pain and difficulty mobilising, it does not specifically manifest as **segmental collapse** or a **crescent sign** in the femoral head itself. *Septic arthritis from surgical site infection* - Septic arthritis presents more acutely with severe pain, **fever**, warmth, and often a marked inability to bear weight due to significant **joint effusion** and inflammation. - Radiographically, it typically shows rapid **joint space narrowing** and destruction of articular cartilage, rather than isolated subchondral collapse. *Osteoarthritis secondary to altered hip biomechanics* - Post-traumatic osteoarthritis is a chronic, degenerative process that develops over years, not typically within six months, and is characterized by **osteophytes**, **joint space narrowing**, and subchondral sclerosis. - It lacks the specific radiological feature of a **crescent sign** and the acute segmental collapse associated with AVN. *Heterotopic ossification causing restricted movement* - This involves the formation of **ectopic bone** in the soft tissues surrounding the joint, which can cause pain and severe restriction of movement. - Radiographs would show discrete **radiopaque masses** outside the bone, not the collapse or crescent sign within the femoral head itself.
Question 220: A 52-year-old man with a history of chronic lower back pain presents with new onset bilateral leg weakness, saddle anaesthesia, and urinary retention over the past 8 hours. On examination, he has reduced anal tone and bilateral absent ankle reflexes. What is the most appropriate immediate management?
- A. Urgent MRI spine and neurosurgical referral for emergency decompression (Correct Answer)
- B. Commence high-dose oral prednisolone and arrange outpatient MRI
- C. Admit for bed rest, analgesia, and physiotherapy review
- D. Arrange urgent CT lumbar spine and refer to spinal team within 24 hours
- E. Prescribe gabapentin and refer to chronic pain clinic
Explanation: ***Urgent MRI spine and neurosurgical referral for emergency decompression***- The patient presents with classic signs of **Cauda Equina Syndrome (CES)**, including **saddle anesthesia**, **urinary retention**, and **reduced anal tone**, which necessitates immediate intervention.- An **urgent MRI spine** is the gold standard for definitive diagnosis, and **emergency surgical decompression** is crucial within hours to prevent permanent neurological deficits like bladder and bowel dysfunction.*Commence high-dose oral prednisolone and arrange outpatient MRI*- **High-dose oral prednisolone** is primarily used for inflammatory conditions or metastatic spinal cord compression, not as the primary treatment for mechanical compression in CES.- Arranging an **outpatient MRI** is dangerously delayed; CES is a time-sensitive emergency where delayed diagnosis and treatment lead to irreversible neurological damage.*Admit for bed rest, analgesia, and physiotherapy review*- While **bed rest** and **analgesia** provide symptomatic relief, they do not address the underlying **spinal cord or nerve root compression** that defines CES.- **Physiotherapy** is inappropriate for an acute neurosurgical emergency and cannot resolve the mechanical compression causing the severe neurological deficits.*Arrange urgent CT lumbar spine and refer to spinal team within 24 hours*- An **urgent CT lumbar spine** can show bony pathology but is inferior to **MRI** for visualizing soft tissues like discs, ligaments, and the cauda equina nerve roots.- While urgent, a **24-hour referral** might be too long given the rapid progression and time-critical nature of CES, where outcomes are better with earlier decompression.*Prescribe gabapentin and refer to chronic pain clinic*- **Gabapentin** is used for neuropathic pain management, which addresses a symptom but not the root cause of acute neurological compression.- Referring to a **chronic pain clinic** is inappropriate for an acute, rapidly evolving neurological emergency like CES, which requires immediate specialist intervention.
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