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2. Trauma MCQs

Practice Set 115 of 640

This practice set contains high-yield board review questions covering key concepts in 2. Trauma. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 2281

Topic: 2. Trauma

Which of the following is considered the most significant factor contributing to rotational malunion after non-operative management of a both bones forearm fracture in an adult?

. Age of the patient
. Initial displacement of the fracture fragments
. Inadequate immobilization (e.g., short arm cast)
. Violation of the interosseous membrane during injury
. Lack of anatomical reduction

Correct Answer & Explanation

. Lack of anatomical reduction

Explanation

Correct Answer: ELack of anatomical reduction (Option E) is the most significant factor for rotational malunion in adult forearm fractures. The forearm's pronation and supination are complex, involving precise interaction between the radius and ulna and the interosseous membrane. Even small degrees of angular or rotational malreduction (typically >10-15 degrees) can significantly impair forearm rotation and lead to substantial functional deficits. While initial displacement (Option B) makes anatomical reduction more challenging, and inadequate immobilization (Option C) can lead to loss of reduction, thefinal stateof malreduction is the direct cause of the malunion. Violation of the interosseous membrane during injury (Option D) is a factor contributing to instability and difficulty achieving reduction, but rotational malunion specifically links to the final achieved alignment, or lack thereof. Age (Option A) impacts remodeling potential, but in adults, remodeling is minimal, making anatomical reduction paramount.

Question 2282

Topic: 2. Trauma

A 7-year-old presents with a completely displaced mid-diaphyseal both bones forearm fracture. After an unsuccessful attempt at closed reduction and casting, what is the most appropriate next step in management?

. Repeat closed reduction under general anesthesia and apply a sugar tong splint.
. Open reduction and internal fixation with 3.5mm dynamic compression plates.
. Flexible intramedullary nailing (FIN) of both radius and ulna.
. Application of an external fixator for temporary stabilization.
. Observation with serial radiographs for remodeling potential.

Correct Answer & Explanation

. Flexible intramedullary nailing (FIN) of both radius and ulna.

Explanation

Correct Answer: CFor unstable and completely displaced diaphyseal forearm fractures in children where closed reduction fails, flexible intramedullary nailing (FIN) is generally the treatment of choice (Option C). FIN provides stable fixation, allows for early motion, and importantly, preserves the growth plates, which is a major concern in pediatric fractures. Plating (Option B) is generally reserved for older adolescents (near skeletal maturity) or specific complex cases in children due to potential issues with growth plate injury, larger dissection, and the need for hardware removal. Repeating closed reduction (Option A) without a plan for definitive fixation if it fails again is not the most appropriate 'next step' after an initial failure. External fixation (Option D) is typically reserved for open fractures, highly comminuted fractures, or situations with significant soft tissue injury. Observation (Option E) is inappropriate for a completely displaced fracture after failed reduction, as remodeling potential is limited for rotational or significant angular deformities that are not adequately reduced.

Question 2283

Topic: 2. Trauma

Which of the following describes the typical displacement of the proximal radial fracture fragment in a mid-diaphyseal radial fracture that is proximal to the insertion of the pronator teres?

. Neutral rotation and mild dorsal angulation.
. Pronated and radially angulated.
. Supinated and radially translated.
. Supinated and ulnarly angulated.
. Pronated and volarly angulated.

Correct Answer & Explanation

. Supinated and radially translated.

Explanation

Correct Answer: CIf the radial shaft fracture is proximal to the insertion of the pronator teres (which inserts at the mid-shaft), the powerful supinator muscles (biceps brachii and supinator) act unopposed on the proximal fragment, leading to a supinated position. The distal fragment, still attached to the pronator teres and pronator quadratus, tends to pronate. This creates a significant rotational malalignment that must be corrected during reduction and fixation to avoid loss of forearm rotation. The proximal fragment is also often radially translated due to muscle pull. Therefore, the proximal fragment is typically supinated and radially translated (Option C).

Question 2284

Topic: 2. Trauma

A 35-year-old male sustains an isolated, closed, mid-shaft both bones forearm fracture. He undergoes ORIF with plates and screws. Four hours post-operatively, he complains of severe pain disproportionate to the injury, increasing with passive stretch of fingers, and develops paresthesias in the median nerve distribution. His distal pulses are palpable. What is the most appropriate next step?

. Reassure the patient and increase analgesia.
. Obtain an immediate CT scan of the forearm.
. Remove the surgical dressing to assess for tight bandage.
. Measure forearm compartment pressures urgently.
. Elevate the limb and apply ice packs.

Correct Answer & Explanation

. Measure forearm compartment pressures urgently.

Explanation

Correct Answer: DThe patient's symptoms (severe pain disproportionate to injury, pain with passive stretch of the fingers, paresthesias in the median nerve distribution, and palpable pulses) are classic signs of acute compartment syndrome. While removing a tight dressing (Option C) might alleviate external compression in some cases, themost appropriate next stepin a suspected acute compartment syndrome, especially post-operatively, is to urgently measure forearm compartment pressures (Option D). This is the definitive diagnostic test. Reassurance (Option A) and increasing analgesia (Option A) are dangerous as they mask symptoms and delay critical intervention. A CT scan (Option B) is not indicated for diagnosing compartment syndrome. Elevation (Option E) can reduce blood flow and worsen ischemia in an already compromised limb with compartment syndrome.

Question 2285

Topic: 2. Trauma

Which of the following is a recognized long-term complication unique to both bones forearm fractures, particularly challenging for restoring full function?

. Non-union of the radius
. Infection of the ulna
. Post-traumatic arthritis of the wrist
. Heterotopic ossification leading to synostosis
. Refracture after hardware removal

Correct Answer & Explanation

. Heterotopic ossification leading to synostosis

Explanation

Correct Answer: DHeterotopic ossification leading to synostosis (Option D) is a unique and particularly debilitating complication of both bones forearm fractures, especially after open reduction and internal fixation. It involves abnormal bone formation between the radius and ulna, fusing the two bones and severely limiting or completely eliminating pronation and supination. This profoundly impacts the unique rotational function of the forearm. While non-union (Option A), infection (Option B), and refracture (Option E) are general complications of fractures, and post-traumatic arthritis (Option C) can occur, synostosis is specific to the interosseous space of the forearm and directly impairs its most critical function.

Question 2286

Topic: 2. Trauma

When assessing acceptable reduction criteria for adult diaphyseal both bones forearm fractures, what is the maximum acceptable rotational malalignment to avoid significant functional impairment?

. 5 degrees
. 10 degrees
. 15 degrees
. 20 degrees
. 30 degrees

Correct Answer & Explanation

. 10 degrees

Explanation

Correct Answer: BFor adult diaphyseal forearm fractures, the widely accepted maximum rotational malalignment to avoid significant functional impairment is generally less than 10 degrees (Option B). While some literature suggests up to 15 degrees may be tolerated in specific circumstances, aiming for less than 10 degrees is crucial to preserve the complex coupled motion of forearm pronation/supination. Rotational malalignment is poorly tolerated functionally because even small degrees can lead to a significant loss of forearm rotation, impacting daily activities. Other acceptable criteria typically include less than 10 degrees of angulation and less than 5mm of shortening.

Question 2287

Topic: 2. Trauma

What is the primary biomechanical advantage of fixing both bones in a diaphyseal forearm fracture with separate plates over a single intramedullary nail for both?

. Less surgical exposure required.
. Reduced risk of infection.
. Superior rotational stability.
. Earlier hardware removal.
. Better remodeling potential.

Correct Answer & Explanation

. Superior rotational stability.

Explanation

Correct Answer: CPlating both bones with separate plates provides superior rotational stability (Option C) compared to attempting to nail both bones. Plates applied to the tension and compression sides of the bone effectively neutralize bending and torsional forces, which are critical in the forearm due to its unique rotational function. Intramedullary nails primarily resist bending and axial forces but provide less rotational stability, especially in the forearm where the two bones must rotate relative to each other. This lack of rotational control with intramedullary nailing in adults can lead to higher rates of rotational malunion. Less surgical exposure (Option A) is generally not true for plating two bones compared to nailing. Risk of infection (Option B) and hardware removal timing (Option D) are not primary biomechanical advantages. Remodeling potential (Option E) is mainly relevant in children and not a biomechanical advantage of fixation type in adults.

Question 2288

Topic: 2. Trauma

The interosseous membrane plays a crucial role in forearm stability. In the context of a Galeazzi fracture, which of the following best describes its primary function that is compromised by the injury?

. It provides the primary attachment site for the wrist extensor muscles.
. It separates the anterior and posterior compartments of the forearm.
. It transmits axial loads from the radius to the ulna and resists proximal migration of the radius.
. It houses the major neurovascular bundles of the forearm.
. It lubricates the articulating surfaces of the radius and ulna.

Correct Answer & Explanation

. It transmits axial loads from the radius to the ulna and resists proximal migration of the radius.

Explanation

Correct Answer: CThe interosseous membrane (IOM) is a strong fibrous sheet connecting the radius and ulna. Its fibers run obliquely from the radius distally and medially to the ulna proximally. This orientation is critical for two main functions: 1) It transmits axial loads from the hand, through the radius, to the ulna, distributing forces across the forearm. 2) More importantly in the context of a Galeazzi fracture, it resists longitudinal displacement and prevents proximal migration of the radius relative to the ulna. When the radial shaft fractures, this load-sharing and stabilizing function is compromised, contributing significantly to the instability of the distal radioulnar joint (DRUJ) and allowing for radial shortening.Option A is incorrect; wrist extensors primarily attach to the humerus and dorsal forearm bones. Option B is incorrect; fascial septa separate the compartments, not the IOM. Option D is incorrect; neurovascular bundles run in fascial compartments, not within the IOM itself. Option E is incorrect; synovial fluid lubricates joints, not the IOM.

Question 2289

Topic: 2. Trauma

A 35-year-old male presents with a distal third radial shaft fracture. During radiographic evaluation, which of the following findings is most reliable for predicting associated distal radioulnar joint (DRUJ) instability?

. Radial shortening greater than 5 mm
. Volar comminution of the radius
. Volar tilt of 15 degrees
. Intact ulnar styloid
. Associated radial head fracture

Correct Answer & Explanation

. Radial shortening greater than 5 mm

Explanation

Radiographic signs highly predictive of DRUJ instability in Galeazzi fractures include radial shortening greater than 5 mm, fracture of the ulnar styloid base, and widening of the DRUJ space on the PA radiograph.

Question 2290

Topic: 2. Trauma

Which of the following patients with a distal radius fracture is the most appropriate candidate for the application of a dorsal spanning (distraction) plate?

. A 25-year-old with a simple extra-articular metaphyseal fracture
. A 65-year-old polytrauma patient requiring immediate upper extremity weight-bearing for transfers
. A 40-year-old with an isolated volar Barton fracture
. A 70-year-old with a minimally displaced osteoporotic fracture
. A 12-year-old with a displaced Salter-Harris II fracture

Correct Answer & Explanation

. A 65-year-old polytrauma patient requiring immediate upper extremity weight-bearing for transfers

Explanation

Dorsal spanning plates are ideal for highly comminuted intra-articular distal radius fractures, particularly in polytrauma patients who require upper extremity weight-bearing to facilitate early mobilization and transfers.

Question 2291

Topic: 2. Trauma

A 42-year-old male sustains an isolated fracture of the ulnar diaphysis (nightstick fracture) from a direct blow. Under what conditions is open reduction and internal fixation generally indicated over nonoperative management?

. Displacement less than 25 percent
. Angulation less than 10 degrees
. Displacement greater than 50 percent
. Location in the distal third of the ulna without angulation
. Associated superficial skin abrasions

Correct Answer & Explanation

. Displacement greater than 50 percent

Explanation

Isolated ulnar shaft fractures can successfully be treated with a functional brace if minimally displaced. Open reduction and internal fixation is indicated if there is greater than 50 percent displacement or more than 10 degrees of angulation.

Question 2292

Topic: 2. Trauma

A 28-year-old male develops severe pain out of proportion following closed reduction of a both-bone forearm fracture. Passive extension of the digits elicits excruciating pain. Which fascial compartment of the forearm is typically the most severely affected in this condition?

. Superficial volar
. Deep volar
. Dorsal
. Mobile wad
. Pronator compartment

Correct Answer & Explanation

. Deep volar

Explanation

Forearm compartment syndrome most frequently and severely affects the deep volar compartment. This compartment contains critical structures including the flexor digitorum profundus (FDP) and flexor pollicis longus (FPL).

Question 2293

Topic: 2. Trauma

A 40-year-old male sustains an Essex-Lopresti injury. He undergoes radial head excision and pinning of the DRUJ. Six months later, he complains of severe ulnar-sided wrist pain. What is the most likely cause of his symptoms?

. Proximal migration of the radius with ulnocarpal impaction
. Nonunion of the ulnar styloid
. Complex regional pain syndrome
. Avascular necrosis of the scaphoid
. Radio-capitellar arthritis

Correct Answer & Explanation

. Proximal migration of the radius with ulnocarpal impaction

Explanation

Essex-Lopresti injuries involve disruption of the interosseous membrane. Excision of the radial head in this setting removes the secondary stabilizer to proximal radial migration, leading to profound longitudinal instability and ulnocarpal impaction.

Question 2294

Topic: 2. Trauma

A 28-year-old male sustains a midshaft both-bone forearm fracture. He undergoes ORIF through two separate surgical incisions. Postoperatively, he develops a radio-ulnar synostosis. Which of the following is the most significant risk factor for developing this complication?

. Use of dynamic compression plates
. Fractures occurring at the same level in the mid-diaphysis
. Open reduction utilizing separate incisions
. Early implementation of active range of motion
. Utilization of locking screws

Correct Answer & Explanation

. Fractures occurring at the same level in the mid-diaphysis

Explanation

Risk factors for radioulnar synostosis after both-bone forearm fractures include fractures at the same level, closed head injuries, severe soft tissue trauma, and using a single incision to approach both bones.

Question 2295

Topic: 2. Trauma

A 45-year-old laborer sustains an isolated fracture of the ulnar shaft (nightstick fracture) from a direct blow. Radiographs show a midshaft transverse fracture with 5 degrees of angulation and 20% displacement. What is the most appropriate initial management?

. Open reduction and internal fixation with a 3.5mm plate
. Intramedullary nailing of the ulna
. Functional bracing and early range of motion
. Long arm cast for 12 weeks
. External fixation

Correct Answer & Explanation

. Functional bracing and early range of motion

Explanation

Isolated ulnar shaft fractures with <50% displacement and <10 degrees of angulation are highly amenable to nonoperative management. Functional bracing allows for early range of motion and yields high union rates.

Question 2296

Topic: 2. Trauma

An 18-year-old male sustains a traumatic scaphoid waist fracture. Which of the following best describes the vascular anatomy that puts this fracture at high risk for nonunion and avascular necrosis?

. Major blood supply enters the proximal pole and flows distally
. Major blood supply is derived from the volar carpal branch of the radial artery
. Blood supply enters the distal pole and flows retrograde to the proximal pole
. The scaphoid relies entirely on synovial diffusion for nutrition
. The ulnar artery provides the dominant supply to the scaphoid waist

Correct Answer & Explanation

. Blood supply enters the distal pole and flows retrograde to the proximal pole

Explanation

The scaphoid receives its primary blood supply from the dorsal carpal branch of the radial artery, which enters the distal pole and flows in a retrograde fashion. This retrograde flow makes proximal pole fractures highly susceptible to avascular necrosis.

Question 2297

Topic: 2. Trauma

A patient is undergoing fixation of a displaced radial styloid fracture (Chauffeur's fracture). Which carpal ligament injury is most frequently associated with this fracture pattern?

. Lunotriquetral interosseous ligament
. Scapholunate interosseous ligament
. Volar radioulnar ligament
. Dorsal radiocarpal ligament
. Ulnar collateral ligament

Correct Answer & Explanation

. Scapholunate interosseous ligament

Explanation

Chauffeur's fractures (radial styloid shear fractures) are frequently associated with scapholunate dissociation. The force pulling off the styloid also commonly avulses or tears the stout extrinsic and intrinsic ligaments attached there.

Question 2298

Topic: 2. Trauma

A 25-year-old male sustains an isolated, closed midshaft ulnar fracture (nightstick fracture) from a direct blow. Radiographs show 5 degrees of angulation and 20% displacement. What is the most appropriate initial management?

. Open reduction and internal fixation with a 3.5mm dynamic compression plate
. Flexible intramedullary nailing of the ulna
. Functional bracing and early range of motion
. Long arm cast immobilization for 6 weeks
. Short arm cast immobilization for 8 weeks

Correct Answer & Explanation

. Functional bracing and early range of motion

Explanation

Nondisplaced or minimally displaced (less than 50% displacement, less than 10 degrees angulation) isolated ulnar shaft fractures are best treated nonoperatively. Functional bracing allows early mobilization with high union rates and excellent functional outcomes.

Question 2299

Topic: 2. Trauma

During open reduction and internal fixation of both bone forearm fractures, anatomic restoration of the radial bow is critical to maximize which of the following functional outcomes?

. Wrist flexion and extension
. Elbow flexion and extension
. Forearm pronation and supination
. Grip strength
. Thumb opposition

Correct Answer & Explanation

. Forearm pronation and supination

Explanation

The anatomical radial bow is essential for allowing the radius to rotate properly around the fixed ulna. Failure to restore the normal magnitude and location of the radial bow significantly limits post-operative forearm supination and pronation.

Question 2300

Topic: 2. Trauma

A 35-year-old male sustains diaphyseal fractures of the radius and ulna at the same level. To minimize the severe complication of radioulnar synostosis, which surgical principle must be strictly followed?

. Fixation utilizing a single extensile volar incision
. Application of autologous bone grafting for both fractures
. Fixation through two separate, distinct incisions
. Use of a single dorsal incision to access both bones
. Avoiding rigid internal fixation to allow micro-motion

Correct Answer & Explanation

. Fixation through two separate, distinct incisions

Explanation

Radioulnar synostosis is a debilitating complication of both-bone forearm fractures, particularly when the fractures are at the same level. The risk is minimized by using two separate incisions (e.g., Henry for the radius, subcutaneous approach for the ulna) to prevent intercommunication of the fracture hematomas.

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