Imaging of Fractures and Dislocations — MCQs
Which of the following is not a differential diagnosis of non-accidental injury?
A 30 year old previously healthy man presented to the emergency department immediately after being involved in a road traffic accident. After clinical examination, scaphoid injury was suspected. A radiograph of the left wrist was obtained and found to be equivocal. What is the best next step?
Proximal humerus fracture which has maximum chances of avascular necrosis
An athlete sustained an injury around the knee joint, suspecting cartilage damage. Which of the following is the investigation of choice?
A 55-year-old male, known smoker, complains of calf pain while walking. He experiences calf pain while walking but can continue walking with effort. Which grade of claudication does this patient fall under?
If a fracture gives the pattern of the striking surface of the weapon it is called
A 4-year-old child while playing suddenly had his elbow pulled by his servant maid's hand and is now continuously crying, not allowing anyone to touch his elbow. He is keeping his elbow extended. What is the most likely diagnosis?
One of the common fractures that occur during boxing by hitting with a closed fist is:
A patient with a shoulder dislocation is at risk of damage to which nerve?
Which MRI finding is suggestive of a torn meniscus in the knee?
Imaging of Fractures and Dislocations Indian Medical PG Practice Questions and MCQs
Question 1: Which of the following is not a differential diagnosis of non-accidental injury?
- A. Osteogenesis imperfecta
- B. Scurvy
- C. Caffey's disease
- D. Osteopetrosis (Correct Answer)
Explanation: ***Correct: Osteopetrosis*** - Osteopetrosis is a rare genetic disorder characterized by **increased bone density** due to defective osteoclast function - While it causes bones to be brittle and prone to fracture, it has **distinctive radiological features** including diffuse sclerosis and "bone-within-bone" appearance - The **increased bone density on X-ray** is pathognomonic and readily distinguishes it from NAI, making it **less likely to be confused** with non-accidental injury in clinical practice - Fractures occur but the radiological pattern is diagnostic of the underlying metabolic bone disease *Incorrect: Osteogenesis imperfecta* - This is a **classic differential** for NAI causing **multiple brittle bone fractures** that can be mistaken for abuse - Features include **blue sclera**, **dentinogenesis imperfecta**, **wormian bones**, and **family history** - Often presents with multiple fractures at different stages of healing, mimicking the pattern seen in NAI *Incorrect: Scurvy* - Caused by **vitamin C deficiency**, leads to defective collagen synthesis - Results in **subperiosteal hemorrhages**, **metaphyseal fractures**, and **periosteal elevation** that closely mimic NAI - Additional features include **gingival bleeding**, **petechiae**, **follicular hyperkeratosis**, and **poor wound healing** *Incorrect: Caffey's disease* - Also known as **infantile cortical hyperostosis**, presents in infants under 6 months - Causes **periosteal reactions**, **bone thickening**, and **soft tissue swelling** in long bones, ribs, and mandible - The periosteal new bone formation can be mistaken for healing fractures from NAI, making it an important differential
Question 2: A 30 year old previously healthy man presented to the emergency department immediately after being involved in a road traffic accident. After clinical examination, scaphoid injury was suspected. A radiograph of the left wrist was obtained and found to be equivocal. What is the best next step?
- A. MRI Scan
- B. Presumptive Casting (Correct Answer)
- C. Bone scintigraphy of wrist
- D. CT Scan
Explanation: ***Presumptive Casting*** - When scaphoid fracture is suspected clinically but **radiographs are equivocal**, conservative management with **presumptive casting** is appropriate. - This prevents potential avascular necrosis and allows for healing if a fracture is present but not yet visible. *MRI Scan* - While an **MRI** is highly sensitive for detecting scaphoid fractures, it is not always immediately available or cost-effective as the very first step following equivocal X-rays in a stable patient. - Delaying immobilization to obtain an immediate MRI could lead to further displacement or complications if a fracture is indeed present. *Bone scintigraphy of wrist* - **Bone scintigraphy** (bone scan) can detect subtle fractures, but it is not typically performed immediately after injury due to its lower specificity and relatively longer time frame to show changes compared to other modalities like MRI. - It involves radiation and is usually reserved for cases where MRI is contraindicated or unavailable and earlier imaging was inconclusive. *CT Scan* - A **CT scan** is excellent for visualizing cortical bone and complex fractures but is less sensitive than MRI for detecting occult scaphoid fractures or soft tissue injuries. - It also involves significant radiation exposure, making it a secondary option to MRI or conservative management for initial detection.
Question 3: Proximal humerus fracture which has maximum chances of avascular necrosis
- A. One part
- B. Two part
- C. Three part
- D. Four part (Correct Answer)
Explanation: ***Four part fracture*** - A **four-part proximal humerus fracture** typically involves displacement of the humeral head, greater tuberosity, lesser tuberosity, and humeral shaft. - This extensive displacement significantly disrupts the **blood supply** to the humeral head, specifically the **arcuate artery** and its branches, leading to a high risk of **avascular necrosis**. *One part fracture* - A **one-part fracture** indicates that the fracture fragments are minimally displaced (<1 cm or <45° angulation). - The **blood supply** to the humeral head remains largely intact, resulting in a very low risk of avascular necrosis. *Two part fracture* - A **two-part fracture** involves displacement of one major fragment (e.g., surgical neck or tuberosity) from the humeral head. - While there is some disruption, the overall risk of **avascular necrosis** is lower compared to more complex fractures. *Three part fracture* - A **three-part fracture** involves separate displacement of the humeral head and two tuberosities. - This fracture pattern causes more significant disruption to the **vascularity** of the humeral head than two-part fractures but generally less than four-part fractures.
Question 4: An athlete sustained an injury around the knee joint, suspecting cartilage damage. Which of the following is the investigation of choice?
- A. Clinical examination
- B. Arthroscopy (Correct Answer)
- C. Arthrotomy
- D. X-ray
Explanation: ***Arthroscopy*** - **Arthroscopy** is the definitive investigation for **cartilage damage** as it allows for direct visualization of the knee joint's internal structures. - It not only confirms the diagnosis but can also facilitate simultaneous **repair or débridement** of damaged cartilage. *X-ray* - **X-rays** are primarily used to assess **bone structures** and detect fractures or significant joint space narrowing, not soft tissue injuries like cartilage. - They are generally **insufficient** for diagnosing subtle or early cartilage damage. *Clinical examination* - A **clinical examination** is crucial for initial assessment and suspicion of cartilage injury, but it cannot definitively diagnose the extent or type of cartilage damage. - It helps guide further investigations but is **not specific enough** to confirm cartilage integrity. *Arthrotomy* - **Arthrotomy** involves a larger incision to open the joint, which is more **invasive** than arthroscopy and typically reserved for open surgical repairs or complex reconstructions, not as a primary diagnostic tool for cartilage. - It carries a **higher risk of complications**, such as infection and prolonged recovery, compared to arthroscopy.
Question 5: A 55-year-old male, known smoker, complains of calf pain while walking. He experiences calf pain while walking but can continue walking with effort. Which grade of claudication does this patient fall under?
- A. Grade I (Mild claudication)
- B. Grade II (Moderate claudication) (Correct Answer)
- C. Grade III (Severe claudication)
- D. Grade IV (Ischemic rest pain)
Explanation: ***Grade II (Moderate claudication)*** - **Grade II claudication** is characterized by **intermittent claudication** where the patient experiences pain while walking but can **continue walking with effort**. - This level of claudication reflects a moderate degree of peripheral arterial disease, where blood flow is sufficiently compromised to cause pain with exertion but not severe enough to force immediate cessation of activity. - The patient in this scenario can continue ambulation despite discomfort, which is the defining feature of this grade. *Grade I (Mild claudication)* - **Grade I claudication** involves discomfort or pain that the patient can **tolerate without significantly altering their gait or pace**. - In this stage, the pain is minimal, and the patient may perceive it as a dull ache or mild fatigue rather than true pain. - Walking can continue without significant effort or limitation. *Grade III (Severe claudication)* - **Grade III claudication** is marked by pain that is **severe enough to stop the patient from walking within a short distance** (typically less than 200 meters). - The pain forces the patient to rest and recover before they can resume walking. - This represents significant functional limitation in daily activities. *Grade IV (Ischemic rest pain)* - **Grade IV**, also known as **critical limb ischemia**, involves **pain even at rest**, especially in the feet or toes, often worsening at night when the limb is elevated. - This stage indicates severe arterial obstruction and is frequently associated with **ulcers, non-healing wounds, or gangrene**. - This represents advanced peripheral arterial disease requiring urgent intervention. **Note:** This grading system is a simplified clinical classification. The standard medical classifications for peripheral arterial disease are the **Fontaine classification** (Stages I-IV) and **Rutherford classification** (Categories 0-6).
Question 6: If a fracture gives the pattern of the striking surface of the weapon it is called
- A. Pond fracture
- B. Signature fracture (Correct Answer)
- C. Ring fracture
- D. Comminuted fracture
Explanation: ***Signature fracture*** - A **signature fracture** is a term used when the bone fracture pattern directly reflects or reproduces the shape of the imparting object or weapon. - This type of fracture provides crucial forensic evidence, directly linking the injury to a specific weapon. *Pond fracture* - A **pond fracture** is a type of depressed skull fracture, typically seen in infants, where the bone is indented without complete disruption, resembling an indentation in a flexible surface. - It does not involve the replication of the weapon's striking surface but rather a localized depression. *Ring fracture* - A **ring fracture** (or foramen magnum fracture) is a fracture around the base of the skull, specifically encircling the foramen magnum. - These fractures are usually caused by an axial load impact (e.g., a fall on the head or feet) or hyperextension/hyperflexion injuries, not by replicating an object's surface. *Comminuted fracture* - A **comminuted fracture** is characterized by the bone breaking into several fragments, often three or more pieces, at the site of injury. - While it indicates high-energy trauma, it describes the number of bone fragments and not the pattern reflecting the striking object.
Question 7: A 4-year-old child while playing suddenly had his elbow pulled by his servant maid's hand and is now continuously crying, not allowing anyone to touch his elbow. He is keeping his elbow extended. What is the most likely diagnosis?
- A. Radial head fracture
- B. Pulled elbow (Correct Answer)
- C. Elbow dislocation
- D. Supracondylar fracture
Explanation: ***Pulled elbow*** - This classic presentation involves a sudden pull on the extended arm, causing the **annular ligament** to slip over the **radial head**, characteristic of a pulled elbow (Nursemaid's elbow). - The child holds the arm in a pronated-extended position, refusing to use it due to pain, and cries when the elbow is touched, which aligns with the clinical picture. *Radial head fracture* - While a fracture can occur with trauma, a history of a distinct pulling mechanism and the absence of swelling or deformity make a **pulled elbow** more likely. - A radial head fracture would typically present with more localized pain and potentially **crepitus** or obvious swelling upon examination. *Supracondylar fracture* - This fracture usually results from a fall onto an outstretched hand, a different mechanism than described. - A supracondylar fracture would typically involve significant swelling, **ecchymosis**, and potential neurovascular compromise, which are not mentioned here. *Elbow dislocation* - Elbow dislocations usually result from high-energy trauma and present with obvious deformity and severe pain. - The history of a "pull" and the child holding the arm in an **extended, pronated position** are more consistent with a pulled elbow than a full dislocation.
Question 8: One of the common fractures that occur during boxing by hitting with a closed fist is:
- A. Monteggia fracture dislocation
- B. Galeazzi fracture dislocation
- C. Bennett's fracture dislocation (Correct Answer)
- D. Smith's fracture
Explanation: ***Bennett's fracture dislocation*** - This is an **intra-articular fracture** of the base of the **first metacarpal**, extending into the carpometacarpal (CMC) joint. - It is frequently caused by axial compression with the thumb in a flexed and adducted position, a common injury mechanism in **punching a hard object** during boxing. *Monteggia fracture dislocation* - This injury involves a fracture of the **proximal ulna** coupled with an **anterior dislocation of the radial head**. - It is typically caused by a direct blow to the forearm or a fall on an outstretched hand with a hyperpronated forearm, not a direct punch. *Galeazzi fracture dislocation* - This involves a fracture of the **distal radius** with an associated **dislocation of the distal radioulnar joint (DRUJ)**. - It results from a fall on an outstretched hand with a hyperpronated forearm, which is not consistent with a boxing injury. *Smith's fracture* - Also known as a **reverse Colles' fracture**, this is a fracture of the **distal radius** with **volar displacement of the distal fragment**. - It typically results from a fall on a flexed wrist or a direct blow to the back of the wrist, not a punching injury.
Question 9: A patient with a shoulder dislocation is at risk of damage to which nerve?
- A. Median nerve
- B. Axillary nerve (Correct Answer)
- C. Radial nerve
- D. Musculocutaneous nerve
Explanation: ***Axillary nerve*** - The **axillary nerve** wraps around the surgical neck of the humerus, making it highly susceptible to injury during **anterior shoulder dislocations** [1]. - Damage can lead to weakness in **deltoid** and **teres minor** muscles, causing difficulty with shoulder abduction, and sensory loss over the lateral shoulder. *Median nerve* - The **median nerve** is primarily involved in innervation of the anterior forearm and hand, and is typically not directly compromised by a simple shoulder dislocation. - Injury to the median nerve is more commonly associated with trauma to the **elbow** or **wrist**, or conditions like **carpal tunnel syndrome**. *Radial nerve* - The **radial nerve** courses along the posterior aspect of the humerus and is more vulnerable in **mid-shaft humeral fractures** or compression injuries in the upper arm [2]. - It is responsible for innervation of the triceps and extensor muscles of the forearm and hand, making it less likely to be affected by a shoulder dislocation. *Musculocutaneous nerve* - The **musculocutaneous nerve** innervates the biceps and brachialis muscles and supplies sensation to the lateral forearm. - While it originates from the brachial plexus near the shoulder, its path makes it relatively protected from isolated shoulder dislocation injuries compared to the axillary nerve.
Question 10: Which MRI finding is suggestive of a torn meniscus in the knee?
- A. Loss of cartilage
- B. Increased signal intensity in the meniscus (Correct Answer)
- C. Effusion
- D. Bone marrow edema
Explanation: ***Increased signal intensity in the meniscus*** A torn meniscus on MRI typically shows **increased signal intensity** within the meniscal substance that **extends to at least one articular surface**, which is the key diagnostic criterion. This high signal indicates **fluid within the tear** or degenerative changes. The signal must reach the surface to differentiate a true tear from intrasubstance degeneration, which shows signal that does not reach the surface. *Loss of cartilage* **Cartilage loss** is characteristic of **osteoarthritis** or chronic degenerative joint disease, not specifically an acute meniscal tear. While it can coexist with meniscal tears as part of degenerative joint disease, it is not a direct indicator of a tear within the meniscus itself. *Effusion* A **knee effusion** (fluid within the joint) is a general sign of joint irritation or injury and can be present with various conditions, including meniscal tears, ligament injuries, and arthritis. However, it is a **non-specific finding** and does not directly confirm a meniscal tear. *Bone marrow edema* **Bone marrow edema** is often seen with **bone bruises**, stress fractures, or osteonecrosis. It indicates stress or injury to the bone rather than soft tissue injury, and is not directly indicative of a meniscal tear.
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