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2. Trauma MCQs

Practice Set 68 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 1341

Topic: 2. Trauma

A 38-year-old carpenter falls from a ladder, sustaining an injury to his left forearm. Radiographs reveal a fracture of the distal third of the radial diaphysis with associated dorsal dislocation of the distal ulna. Which eponym correctly identifies this injury pattern?

. Monteggia fracture
. Colles fracture
. Galeazzi fracture
. Smith fracture
. Barton fracture

Correct Answer & Explanation

. Galeazzi fracture

Explanation

Correct Answer: CThe Galeazzi fracture-dislocation is classically defined as a fracture of the distal third of the radial diaphysis with concomitant disruption of the distal radioulnar joint (DRUJ), often presenting with dorsal dislocation of the ulna. Monteggia involves an ulnar fracture with radial head dislocation. Colles and Smith are distal radius fractures. Barton is an intra-articular distal radius fracture.

Question 1342

Topic: 2. Trauma

A 55-year-old patient undergoes ORIF for a Galeazzi fracture. Postoperatively, she develops malunion of the radial shaft with persistent radial shortening and dorsal subluxation of the ulna at the DRUJ. Which of the following long-term complications is most likely to result from this malunion?

. Radial nerve palsy
. Limited pronation and supination of the forearm
. Avascular necrosis of the lunate
. Flexor tendon rupture
. Compartment syndrome

Correct Answer & Explanation

. Limited pronation and supination of the forearm

Explanation

Correct Answer: BPersistent radial shortening after a Galeazzi fracture leads to a positive ulnar variance, which can cause significant mechanical problems at the DRUJ. This often results in painful impingement and limited range of motion, particularly in pronation and supination, as the altered geometry and DRUJ subluxation restrict normal kinematic coupling between the radius and ulna. Avascular necrosis of the lunate (Kienbock's disease) is associated with negative ulnar variance. Radial nerve palsy is less common as a direct complication of malunion. Flexor tendon rupture and compartment syndrome are not direct long-term consequences of this specific malunion pattern.

Question 1343

Topic: 2. Trauma

In the setting of a Galeazzi fracture, a radius fracture located within what distance from the radiocarpal articular surface correlates with the highest risk of distal radioulnar joint (DRUJ) instability?

. 2.5 cm
. 5.0 cm
. 7.5 cm
. 10.0 cm
. 12.5 cm

Correct Answer & Explanation

. 7.5 cm

Explanation

Radius fractures located within 7.5 cm of the articular surface have a 55% rate of DRUJ instability, compared to only 6% for more proximal fractures. This proximity defines the classic type I Galeazzi fracture.

Question 1344

Topic: 2. Trauma

A 35-year-old female presents with an isolated ulnar shaft fracture (nightstick fracture) following a direct blow. Which of the following radiographic parameters is an accepted indication for operative intervention (ORIF)?

. Fracture located in the distal third
. Displacement greater than 50% of the shaft diameter
. Angulation of less than 5 degrees
. A purely transverse fracture pattern
. An intact interosseous membrane

Correct Answer & Explanation

. Displacement greater than 50% of the shaft diameter

Explanation

Indications for operative management of isolated ulnar shaft fractures include displacement greater than 50%, angulation greater than 10 degrees, or fractures involving the proximal third. These factors significantly increase the risk of nonunion and poor functional outcomes.

Question 1345

Topic: 2. Trauma

A 42-year-old male requires ORIF for a both-bone forearm fracture. To minimize the risk of developing a cross-union (radioulnar synostosis), which surgical strategy should be employed?

. Use of a single extensile volar incision for both bones
. Immediate post-operative immobilization in a cast for 6 weeks
. Utilizing separate fascial incisions for the radius and ulna approaches
. Placement of copious bone graft in the interosseous space
. Extensive circumferential periosteal stripping of both bones

Correct Answer & Explanation

. Utilizing separate fascial incisions for the radius and ulna approaches

Explanation

Radioulnar synostosis is a devastating complication that limits forearm rotation. Risk factors are mitigated by using separate incisions for the radius and ulna, minimizing dissection in the interosseous space, and avoiding bone grafting between the two bones.

Question 1346

Topic: 2. Trauma

According to AO principles for diaphyseal forearm fractures treated with dynamic compression plating, what is the minimum recommended number of bicortical screws (cortices) per main fracture fragment?

. 2 screws (4 cortices)
. 3 screws (6 cortices)
. 5 screws (10 cortices)
. 6 screws (12 cortices)
. 1 screw (2 cortices)

Correct Answer & Explanation

. 3 screws (6 cortices)

Explanation

AO principles dictate that rigid plate osteosynthesis of forearm diaphyseal fractures requires a minimum of 3 bicortical screws, achieving 6 cortices of purchase, on each side of the fracture to ensure adequate biomechanical stability.

Question 1347

Topic: 2. Trauma

A 35-year-old male sustains an isolated midshaft ulnar 'nightstick' fracture after a direct blow. Radiographs show 20% translation and 5 degrees of angulation. What is the most appropriate initial management?

. Open reduction and internal fixation with a 3.5mm dynamic compression plate
. Closed reduction and long-arm casting for 6 weeks
. Functional fracture bracing with early active range of motion
. Intramedullary nailing of the ulna
. External fixation

Correct Answer & Explanation

. Functional fracture bracing with early active range of motion

Explanation

Isolated ulnar shaft fractures with less than 50% displacement and less than 10 degrees of angulation are stable. They are best treated non-operatively with a functional brace and early range of motion.

Question 1348

Topic: 2. Trauma

Which of the following surgical factors poses the highest risk for developing radioulnar synostosis following operative treatment of both-bone forearm fractures?

. Use of dynamic compression plates rather than locking plates
. Delayed fixation of the fractures beyond 7 days
. Operative exposure of both fractures through a single incision
. Use of a tourniquet for more than 90 minutes
. Failure to repair the pronator teres muscle

Correct Answer & Explanation

. Operative exposure of both fractures through a single incision

Explanation

A single incision to approach both the radius and ulna significantly increases the risk of radioulnar synostosis (cross-union). Standard practice utilizes separate volar (Henry) and dorsal/subcutaneous approaches.

Question 1349

Topic: 2. Trauma

A 28-year-old male sustains a Galeazzi fracture. Which of the following radiographic factors is most highly predictive of distal radioulnar joint (DRUJ) instability following anatomic open reduction and internal fixation of the radius?

. Fracture of the radius located 8 cm from the radiocarpal joint
. Fracture of the radius located 4 cm from the radiocarpal joint
. Dorsal comminution of the radial shaft
. Associated ulnar styloid tip fracture
. Initial radial shortening of 2 mm

Correct Answer & Explanation

. Fracture of the radius located 4 cm from the radiocarpal joint

Explanation

Fractures of the radius within 7.5 cm of the articular surface have a significantly higher rate of DRUJ instability (over 50%) compared to more proximal fractures. This proximity disrupts the interosseous membrane's stabilizing fibers near the joint.

Question 1350

Topic: 2. Trauma

A 6-year-old boy sustains a completely displaced midshaft both-bone forearm fracture. Following closed reduction and casting, what is the maximum acceptable angulation in the sagittal and coronal planes for nonoperative management?

. 5 degrees
. 15 degrees
. 25 degrees
. 35 degrees
. 45 degrees

Correct Answer & Explanation

. 15 degrees

Explanation

In children under 9 years old, acceptable alignment for both-bone forearm fractures includes up to 15 degrees of angulation and complete displacement, provided it is bayonet apposed. The tremendous remodeling potential in this age group corrects the deformity.

Question 1351

Topic: 2. Trauma

A 25-year-old male presents with worsening forearm pain, pain with passive finger extension, and paresthesias following a crush injury. If a fasciotomy is performed, release of which specific muscle compartment is most critical early due to its high susceptibility to ischemia?

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

Correct Answer & Explanation

. Deep volar compartment

Explanation

The deep volar compartment, containing the flexor digitorum profundus (FDP) and flexor pollicis longus (FPL), is the most frequently and severely affected in forearm compartment syndrome. Early decompression is vital to prevent Volkmann ischemic contracture.

Question 1352

Topic: 2. Trauma

A 45-year-old female sustains a volar Barton fracture. What is the primary biomechanical function of the volar plate used for fixation in this specific injury pattern?

. Tension band
. Bridging
. Buttress
. Dynamic compression
. Neutralization

Correct Answer & Explanation

. Buttress

Explanation

A volar Barton fracture involves a shear fracture of the volar articular rim. The volar plate acts primarily as a buttress plate to counteract the shearing forces and prevent volar subluxation of the carpus.

Question 1353

Topic: 2. Trauma

Which of the following surgical factors is most strongly associated with the development of a radioulnar synostosis following open reduction and internal fixation of both-bone forearm fractures?

. Use of a single surgical incision for both fractures
. Fixation with 3.5mm dynamic compression plates
. Bone grafting of comminuted segments
. Immobilization for 2 weeks postoperatively
. Repair of the interosseous membrane

Correct Answer & Explanation

. Use of a single surgical incision for both fractures

Explanation

Using a single incision to approach both the radius and ulna significantly increases the risk of cross-union (radioulnar synostosis) and is generally contraindicated. Separate dorsal and volar incisions are standard to preserve tissue planes.

Question 1354

Topic: 2. Trauma

When performing open reduction and internal fixation of an adult midshaft both-bone forearm fracture, what is the minimum recommended number of cortices of screw fixation on each side of the fracture to ensure adequate construct stability?

. 4 cortices
. 5 cortices
. 6 cortices
. 8 cortices
. 10 cortices

Correct Answer & Explanation

. 6 cortices

Explanation

Current AO principles recommend a minimum of 6 cortices (typically three bicortical screws) of fixation on both sides of a diaphyseal forearm fracture. This achieves stable fixation and promotes primary bone healing while allowing early range of motion.

Question 1355

Topic: 2. Trauma
A 5-year-old sustains a traumatic forearm injury resulting in a fracture of the ulnar diaphysis and an associated anterior dislocation of the radial head. According to the Bado classification, what type of Monteggia lesion is this?
. Type I
. Type II
. Type III
. Type IV
. Type V

Correct Answer & Explanation

. Type I

Explanation

A Bado Type I Monteggia fracture is characterized by an anterior dislocation of the radial head with an associated fracture of the ulnar diaphysis. It is the most common type, especially in the pediatric population.

Question 1356

Topic: 2. Trauma

An 18-year-old male sustains an isolated fracture of the ulnar shaft (nightstick fracture) following a direct blow. Which of the following parameters is an indication for operative intervention rather than functional bracing?

. Angulation of 8 degrees
. Displacement of 30% of the shaft diameter
. Location in the distal one-third of the ulna
. Displacement of greater than 50% of the shaft diameter
. Associated intact radius

Correct Answer & Explanation

. Displacement of greater than 50% of the shaft diameter

Explanation

Indications for operative fixation of isolated ulnar shaft fractures include displacement greater than 50%, angulation greater than 10 degrees, or proximal third involvement. Fractures falling below these thresholds can be treated successfully with functional bracing.

Question 1357

Topic: 2. Trauma

Four weeks after nonoperative management of a non-displaced distal radius fracture, a 55-year-old female experiences a sudden loss of active thumb extension. What is the pathomechanics underlying this complication?

. Primary tendon laceration from fracture fragments
. Attritional wear secondary to a non-displaced Lister's tubercle fracture
. Ischemic necrosis of the extensor pollicis longus tendon
. Entrapment of the tendon within the fracture site
. Adhesive capsulitis of the first extensor compartment

Correct Answer & Explanation

. Ischemic necrosis of the extensor pollicis longus tendon

Explanation

Extensor pollicis longus (EPL) rupture after non-displaced distal radius fractures is classically attributed to localized ischemia. The tendon becomes compressed within the tight third extensor compartment due to fracture hematoma and swelling.

Question 1358

Topic: 2. Trauma

A 28-year-old male sustains a classic Galeazzi fracture-dislocation. Radiographs demonstrate a fracture of the distal third of the radial shaft with associated dorsal displacement of the distal radius fragment and disruption of the distal radioulnar joint (DRUJ). Which muscle is the primary deforming force responsible for the proximal migration and radial shortening of the distal fracture fragment?

. Pronator teres
. Pronator quadratus
. Brachioradialis
. Extensor carpi radialis brevis
. Flexor carpi radialis

Correct Answer & Explanation

. Brachioradialis

Explanation

The brachioradialis inserts on the radial styloid and acts as the primary deforming force causing proximal migration and radial shortening in Galeazzi fractures. The pronator quadratus typically pulls the distal fragment volarly and ulnarly.

Question 1359

Topic: 2. Trauma

A 7-year-old boy sustains a closed midshaft both-bone forearm fracture. What are the generally accepted upper limits of radiographic deformity in this age group to safely proceed with closed reduction and casting without surgical intervention?

. 10 degrees of angulation and 30 degrees of malrotation
. 15 degrees of angulation and 45 degrees of malrotation
. 20 degrees of angulation and 0 degrees of malrotation
. 5 degrees of angulation and 10 degrees of malrotation
. Strict anatomic reduction is required regardless of age

Correct Answer & Explanation

. 15 degrees of angulation and 45 degrees of malrotation

Explanation

In children under 9 years of age, remodeling potential is high. Acceptable parameters for midshaft both-bone forearm fractures include up to 15 degrees of angulation, 45 degrees of malrotation, and 100% displacement (bayonet apposition).

Question 1360

Topic: 2. Trauma

A 25-year-old man develops severe, unrelenting forearm pain 12 hours after ORIF of a highly comminuted both-bone forearm fracture. He exhibits profound pain with passive extension of his fingers. Measurement of compartment pressures confirms forearm compartment syndrome. Which fascial compartment is most frequently and primarily affected in this clinical scenario?

. Dorsal compartment
. Mobile wad compartment
. Volar compartment
. Pronator quadratus compartment
. Interosseous compartment

Correct Answer & Explanation

. Volar compartment

Explanation

The volar compartment is the most commonly affected compartment in forearm compartment syndrome. It contains the flexor digitorum profundus and superficialis, which explains the classic sign of severe pain with passive digit extension.

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