Trauma — MCQs

A 62-year-old woman presents with a 3-month history of progressive right shoulder pain, limiting her ability to lift her arm for daily activities. She denies neurological symptoms. Physical examination reveals weakness in abduction and external rotation with a normal passive range of motion. She cannot maintain 90 degrees of abduction. There is no motor deficit in the forearm or hand, and pulses and sensation are normal. Which of the following muscles constitute the injured structure?

Q587Easy

Which of the following best describes the patient's wrist fracture?

Q588Easy

What is the typical position of the distal fragment in a fracture of the upper third of the femur shaft?

Q589Medium

All of the following are true about dashboard injuries EXCEPT?

Q590Medium

A 55-year-old woman presents with severe pain in the flexor muscles of the forearm, fixed flexion of the fingers, and swelling, cyanosis, and anesthesia of the fingers following a car crash. Which of the following is the most likely diagnosis?

Trauma Indian Medical PG Practice Questions and MCQs

Question 581: Tardy ulnar nerve palsy is caused by which of the following?

A. Fracture of the lateral epicondyle of the humerus (Correct Answer)
B. Fracture of the medial epicondyle of the humerus
C. Elbow dislocation
D. Supracondylar fracture of the humerus

Explanation: **Explanation:** **Tardy Ulnar Nerve Palsy** is a delayed-onset neuropathy that occurs years after an elbow injury. The primary mechanism is **Cubitus Valgus** (increased carrying angle). **Why Option A is Correct:** The most common cause is a non-union of a **fracture of the lateral epicondyle** (or lateral condyle) of the humerus sustained in childhood. When the lateral condyle fails to unite, the lateral side of the distal humerus stops growing while the medial side continues. This leads to a progressive **Cubitus Valgus deformity**. This deformity stretches the ulnar nerve as it travels behind the medial epicondyle, leading to chronic friction and eventual palsy. **Why Other Options are Incorrect:** * **B. Fracture of the medial epicondyle:** While this can cause *acute* ulnar nerve injury (due to its proximity), it does not typically result in the progressive valgus deformity required for "tardy" (delayed) palsy. * **C. Elbow dislocation:** This usually results in acute nerve injuries (most commonly the median or ulnar nerve) rather than a delayed presentation years later. * **D. Supracondylar fracture:** This is the most common pediatric elbow fracture. It typically leads to **Cubitus Varus** (Gunstock deformity) if malunited. Cubitus varus does not stretch the ulnar nerve; in fact, it may occasionally lead to tardy *posterolateral instability* but not classic tardy ulnar palsy. **Clinical Pearls for NEET-PG:** * **Latency:** The symptoms (wasting of intrinsic hand muscles, clawing) usually appear **10–20 years** after the initial injury. * **Deformity:** Always associate Tardy Ulnar Nerve Palsy with **Cubitus Valgus**. * **Treatment:** The procedure of choice is **Anterior Transposition of the Ulnar Nerve**, where the nerve is moved from its posterior groove to the front of the medial epicondyle to relieve tension.

Question 582: Which of the following is NOT a type of displacement seen in a Colles fracture?

A. Dorsal tilt
B. Ventral tilt (Correct Answer)
C. Dorsal displacement
D. Lateral displacement

Explanation: A **Colles fracture** is a distal radius fracture occurring within 2.5 cm of the wrist joint, typically resulting from a fall on an outstretched hand (FOOSH). The hallmark of this fracture is the **dorsal (posterior)** displacement of the distal fragment, which creates the classic "Dinner Fork Deformity." ### Why "Ventral Tilt" is the Correct Answer: In a Colles fracture, the distal fragment tilts **dorsally** (backwards). A **ventral (volar/anterior) tilt** is the defining characteristic of a **Smith’s fracture**, often referred to as a "Reverse Colles." Therefore, ventral tilt is NOT seen in a Colles fracture. ### Explanation of Incorrect Options: The distal fragment in a Colles fracture typically undergoes six types of displacement: * **Dorsal Tilt (Option A):** The articular surface faces posteriorly instead of its normal slight volar tilt. * **Dorsal Displacement (Option C):** The fragment moves toward the back of the hand. * **Lateral Displacement (Option D):** The fragment moves toward the radial side. * *Other displacements include:* Lateral tilt (radial tilt), impaction, and supination. ### High-Yield Clinical Pearls for NEET-PG: * **Deformity:** Dinner fork deformity (due to dorsal displacement). * **Smith’s Fracture:** Garden spade deformity (due to ventral displacement). * **Barton’s Fracture:** Intra-articular fracture-dislocation of the wrist (can be dorsal or volar). * **Chauffeur’s Fracture:** Intra-articular fracture of the radial styloid process. * **Complication:** The most common late complication of a Colles fracture is **Malunion**; the most common tendon involved is the **Extensor Pollicis Longus (EPL) rupture**.

Question 583: What is the primary action of an intramedullary 'K' nail?

A. Two-point fixation
B. Three-point fixation (Correct Answer)
C. Compression
D. Weight concentration

Explanation: ### Explanation The **Kuntscher nail (K-nail)** is a classic intramedullary (IM) device traditionally used for fractures of the femoral shaft. Its primary mechanism of stability is **three-point fixation**. **1. Why Three-Point Fixation is Correct:** The K-nail has a unique **cloverleaf cross-section**. This design provides elasticity, allowing the nail to be compressed as it is driven into the medullary canal. Once inside, it exerts outward radial pressure against the endosteum. Stability is achieved when the nail makes contact with the bone at a minimum of three points: the proximal entry point, the narrowest part of the canal (isthmus), and the distal metaphysis. This "interference fit" prevents angular and translational displacement. **2. Analysis of Incorrect Options:** * **Two-point fixation:** This is inherently unstable for long bone fractures as it allows for a "toggle" effect or rotation around the two points. * **Compression:** While some modern IM nails use "dynamic locking" to achieve axial compression, the traditional K-nail is a non-locking nail and does not actively compress the fracture site. * **Weight concentration:** This is not a biomechanical principle of fixation. In fact, IM nails are **weight-sharing** devices (unlike plates, which are weight-bearing), allowing for early mobilization. ### High-Yield Clinical Pearls for NEET-PG: * **Ideal Site:** The K-nail is best suited for **transverse, mid-shaft fractures** of the femur where the isthmus is intact. * **Shape:** The cloverleaf design provides resistance to **torsional (rotational) forces**, though it is much weaker in this regard than modern **interlocking nails**. * **Evolution:** In modern orthopaedics, the K-nail has largely been replaced by **Interlocking Intramedullary Nails**, which use proximal and distal bolts to prevent rotation and shortening in comminuted or unstable fractures. * **Working Length:** The stability of a K-nail depends on the "working length"—the distance between the proximal and distal points of contact.

Question 584: An 8-year-old boy falls on a flexed left elbow and suffers a closed, fully displaced flexion type supracondylar fracture. He complains of finger numbness, but will not allow examination of his arm. Which of the following is most likely injured in this fracture?

A. Anterior interosseous nerve
B. Ulnar nerve (Correct Answer)
C. Radial nerve
D. Radial artery

Explanation: ### **Explanation** Supracondylar fractures of the humerus are common pediatric injuries, classified into two types based on the mechanism of injury and the direction of displacement of the distal fragment: **Extension type** (95%) and **Flexion type** (5%). **1. Why Ulnar Nerve is Correct:** In a **flexion-type** supracondylar fracture, the distal fragment is displaced **anteroposteriorly (anteriorly and proximally)**. This anterior displacement of the proximal shaft fragment puts significant tension on the **ulnar nerve** as it passes behind the medial epicondyle. Consequently, the ulnar nerve is the most commonly injured nerve in flexion-type injuries. The patient’s complaint of "finger numbness" (typically in the 4th and 5th digits) is a classic clinical indicator of ulnar nerve paresthesia. **2. Why Other Options are Incorrect:** * **Anterior Interosseous Nerve (AIN):** This is a branch of the median nerve and is the **most common** nerve injured in **extension-type** supracondylar fractures (specifically posterolateral displacement). * **Radial Nerve:** This is the second most common nerve injured in **extension-type** fractures (specifically posteromedial displacement). * **Radial Artery:** While vascular compromise can occur, the **brachial artery** is the vessel at risk in supracondylar fractures (usually extension type), not the radial artery. **3. Clinical Pearls for NEET-PG:** * **Extension Type (Most Common):** Distal fragment moves posteriorly. Nerve at risk: **AIN** (Median nerve). * **Flexion Type (Rare):** Distal fragment moves anteriorly. Nerve at risk: **Ulnar nerve**. * **Gartland Classification:** Used to grade these fractures (Type I: Undisplaced; Type II: Angulated with intact posterior cortex; Type III: Completely displaced). * **Complication:** The most dreaded late complication is **Volkmann’s Ischemic Contracture (VIC)** due to brachial artery involvement or compartment syndrome. * **Deformity:** Malunion typically results in **Cubitus Varus** (Gunstock deformity).

Question 585: What is a bumper fracture?

A. Fracture of fibula
B. Fracture of distal tibia
C. Fracture of medial tibial plateau
D. Fracture of lateral tibial plateau (Correct Answer)

Explanation: ### Explanation **1. Why the Correct Answer is Right:** A **Bumper Fracture** (also known as a Fender fracture) refers to a fracture of the **lateral tibial plateau**. It occurs due to a high-energy **valgus strain** (force applied to the lateral side of the knee). The name originates from a classic mechanism of injury: a pedestrian being struck by the front bumper of a car. When the bumper hits the lateral aspect of the knee, the femur acts as a hammer, driving the lateral femoral condyle into the softer articular surface of the lateral tibial plateau, causing a crush or split fracture. **2. Why the Incorrect Options are Wrong:** * **A. Fracture of fibula:** While the neck of the fibula may be fractured simultaneously due to direct impact, the term "Bumper fracture" specifically refers to the intra-articular tibial plateau injury. * **B. Fracture of distal tibia:** Fractures of the distal tibia (near the ankle) are known as **Pilon fractures** (axial loading) or **Pott’s fractures** (malleolar injuries). * **C. Fracture of medial tibial plateau:** Medial plateau fractures are less common and usually result from a **varus** force. They are often associated with higher energy and more severe ligamentous damage. **3. Clinical Pearls for NEET-PG:** * **Classification:** Tibial plateau fractures are classified using the **Schatzker Classification** (Type II is the most common: split + depression of the lateral plateau). * **Associated Injury:** Always check for **Peroneal nerve** injury (foot drop) and **Lateral Collateral Ligament (LCL)** tears. * **Complication:** The most common early complication is **Compartment Syndrome**; the most common late complication is **Secondary Osteoarthritis**. * **Imaging:** CT scan is the gold standard for preoperative planning to assess the degree of articular depression.

Question 586: A 62-year-old woman presents with a 3-month history of progressive right shoulder pain, limiting her ability to lift her arm for daily activities. She denies neurological symptoms. Physical examination reveals weakness in abduction and external rotation with a normal passive range of motion. She cannot maintain 90 degrees of abduction. There is no motor deficit in the forearm or hand, and pulses and sensation are normal. Which of the following muscles constitute the injured structure?

A. Supraspinatus, infraspinatus, teres major, deltoid
B. Supraspinatus, infraspinatus, teres major, subscapularis
C. Supraspinatus, infraspinatus, teres minor, deltoid
D. Supraspinatus, infraspinatus, teres minor, subscapularis (Correct Answer)

Explanation: **Explanation:** The clinical presentation describes a classic case of a **Rotator Cuff Tear**. The patient exhibits the "Drop Arm Sign" (inability to maintain 90 degrees of abduction) and weakness in external rotation, while maintaining a normal passive range of motion. This dissociation between active and passive movement is hallmark for a tendon/muscle tear rather than adhesive capsulitis (where both are restricted). The **Rotator Cuff** is a functional unit of four muscles that stabilize the glenohumeral joint. The correct anatomical components are: 1. **Supraspinatus:** Initiates abduction (0-15°). 2. **Infraspinatus:** Primary external rotator. 3. **Teres Minor:** External rotator and adductor. 4. **Subscapularis:** Primary internal rotator. **Analysis of Options:** * **Option D (Correct):** Correctly identifies the four SITS muscles (Supraspinatus, Infraspinatus, Teres minor, Subscapularis). * **Options A & B:** Incorrect because they include the **Teres Major**. While the Teres Major helps in adduction and internal rotation, it is *not* part of the rotator cuff. * **Options A & C:** Incorrect because they include the **Deltoid**. The deltoid is the primary abductor of the arm (after 15°) but is a superficial muscle, not part of the stabilizing rotator cuff. **High-Yield NEET-PG Pearls:** * **Most common muscle injured:** Supraspinatus (due to its location under the acromion). * **Investigation of Choice:** MRI is the gold standard for diagnosing rotator cuff tears. * **Clinical Tests:** Jobe’s Test (Empty Can) for Supraspinatus; Hornblower’s Sign for Teres Minor; Lift-off/Gerber’s test for Subscapularis. * **Nerve Supply:** Suprascapular nerve (Supra/Infraspinatus), Axillary nerve (Teres minor), Upper and Lower Subscapular nerves (Subscapularis).

Question 587: Which of the following best describes the patient's wrist fracture?

A. Bennett's fracture
B. Colles fracture (Correct Answer)
C. Jones fracture
D. Salter-Harris fracture

Explanation: ***Colles fracture*** - Affects the **distal radius** with **dorsal displacement** and **dorsal angulation**, creating the characteristic **"dinner fork" deformity** on clinical examination. - Most commonly occurs from a **fall on outstretched hand (FOOSH)** mechanism, particularly in elderly patients with **osteoporosis**. *Bennett's fracture* - This is a fracture-dislocation at the **base of the first metacarpal** (thumb), not involving the wrist or radius. - Requires **surgical fixation** due to instability at the **carpometacarpal joint** of the thumb. *Jones fracture* - Occurs at the **5th metatarsal** in the **foot**, specifically at the **metaphyseal-diaphyseal junction**. - Has poor healing potential due to **watershed blood supply** and often requires **surgical intervention**. *Salter-Harris fracture* - This classification applies to **growth plate injuries** in **pediatric patients** with open physes. - Would not be applicable to typical wrist fractures in adults where **growth plates are closed**.

Question 588: What is the typical position of the distal fragment in a fracture of the upper third of the femur shaft?

A. Adducted (Correct Answer)
B. Abducted
C. Posteriorly displaced
D. Anteriorly displaced

Explanation: In a fracture of the **upper third of the femur shaft**, the displacement of fragments is determined by the powerful muscle groups attached to them. **1. Why Adducted is Correct:** The position of the **distal fragment** is primarily influenced by the **Adductor group of muscles** (Adductor longus, brevis, and magnus). These muscles originate from the pelvis and insert along the linea aspera of the femoral shaft. When the bone is fractured in the upper third, these muscles pull the distal fragment medially, resulting in **Adduction**. **2. Analysis of Other Options:** * **Abducted:** This describes the **proximal fragment**. The proximal fragment is abducted by the Gluteus medius and minimus, and flexed by the Iliopsoas. * **Posteriorly displaced:** While the distal fragment may have some posterior tilt due to the pull of the gastrocnemius (more common in supracondylar fractures), the primary characteristic displacement in upper-third fractures is medial/adduction. * **Anteriorly displaced:** The proximal fragment is the one that appears anteriorly displaced (flexed) due to the Iliopsoas muscle. **High-Yield Clinical Pearls for NEET-PG:** * **Proximal Fragment Position:** Flexed (Iliopsoas), Abducted (Glutei), and Externally Rotated (Short rotators). * **Distal Fragment Position:** Adducted (Adductors) and pulled proximally (Shortening due to Hamstrings and Quadriceps). * **Winquist-Hansen Classification:** Used to grade the comminution of femoral shaft fractures. * **Management:** The gold standard treatment for adult femoral shaft fractures is **Intramedullary (IM) Nailing** (antegrade or retrograde).

Question 589: All of the following are true about dashboard injuries EXCEPT?

A. It is associated with posterior dislocation of the hip.
B. Sciatic nerve may be involved, leading to foot drop.
C. Avascular necrosis of the hip could be a late complication.
D. The point of impact is on the greater trochanter. (Correct Answer)

Explanation: ### Explanation **1. Why Option D is the Correct Answer (The Exception)** In a **dashboard injury**, the point of impact is **not** the greater trochanter. Instead, the force is applied to the **proximal tibia (knee)** while the hip and knee are flexed (as seen in a seated passenger during a head-on collision). This longitudinal force is transmitted along the shaft of the femur toward the hip joint. Because the hip is flexed and adducted in this position, the femoral head is driven posteriorly, out of the acetabulum. Impact on the greater trochanter is typically associated with lateral compression injuries or femoral neck fractures, not classic dashboard dislocations. **2. Analysis of Other Options** * **Option A:** Dashboard injuries are the classic mechanism for **posterior dislocation of the hip** (the most common type of hip dislocation). * **Option B:** The **sciatic nerve** (specifically the peroneal division) lies immediately posterior to the acetabulum. During a posterior dislocation, the femoral head can compress or stretch the nerve, resulting in **foot drop**. * **Option C:** **Avascular Necrosis (AVN)** is a dreaded late complication. The blood supply to the femoral head (via the retinacular vessels) is disrupted during dislocation. The risk of AVN increases significantly if the dislocation is not reduced within 6 hours. **3. NEET-PG Clinical Pearls** * **Position of the Limb:** In posterior hip dislocation, the limb is typically **shortened, adducted, and internally rotated**. (Contrast this with anterior dislocation: abducted and externally rotated). * **Associated Fracture:** Often associated with a fracture of the **posterior lip of the acetabulum**. * **Management:** It is an **orthopaedic emergency**. The first-line treatment is closed reduction (e.g., Allis maneuver or Bigelow's maneuver) under sedation. * **Most Common Nerve Injured:** Sciatic nerve (10-20% of cases).

Question 590: A 55-year-old woman presents with severe pain in the flexor muscles of the forearm, fixed flexion of the fingers, and swelling, cyanosis, and anesthesia of the fingers following a car crash. Which of the following is the most likely diagnosis?

A. Colles' fracture
B. Scaphoid fracture
C. Bennett's fracture
D. Volkmann's ischemic contracture (Correct Answer)

Explanation: ### Explanation The clinical presentation described is a classic case of **Volkmann’s Ischemic Contracture (VIC)**, which is the end-stage result of untreated **Acute Compartment Syndrome** of the forearm. **1. Why Volkmann’s Ischemic Contracture is correct:** Following trauma (like a car crash), increased pressure within the tight fascial compartments of the forearm leads to ischemia of the muscles and nerves. The **flexor digitorum profundus** and **flexor pollicis longus** are most commonly affected. Prolonged ischemia leads to muscle infarction and subsequent fibrosis. This causes the muscles to shorten, resulting in the characteristic **fixed flexion deformity** of the wrist and fingers. The presence of swelling, cyanosis, and anesthesia indicates severe neurovascular compromise. **2. Why other options are incorrect:** * **Colles’ Fracture:** This is a distal radius fracture with dorsal displacement ("dinner fork deformity"). While it causes pain and swelling, it does not typically present with fixed flexion contractures or ischemic signs unless complicated by compartment syndrome. * **Scaphoid Fracture:** Usually presents with tenderness in the anatomical snuffbox following a fall on an outstretched hand. It does not cause forearm muscle contractures. * **Bennett’s Fracture:** This is an intra-articular fracture-dislocation at the base of the first metacarpal (thumb). It is localized to the hand and does not involve the forearm flexors. **3. NEET-PG High-Yield Pearls:** * **Earliest Sign of Compartment Syndrome:** Pain out of proportion to the injury and **pain on passive stretching** of the muscles. * **The 5 P’s:** Pain, Pallor, Paresthesia, Pulselessness, and Paralysis (Note: Pulselessness is a very late sign). * **Volkmann’s Sign:** The finger contracture is relieved by flexing the wrist (which relaxes the tension on the fibrotic flexor tendons). * **Most Common Site:** Supracondylar fracture of the humerus in children is the most common precursor to VIC.

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Trauma — MCQs

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