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2. Trauma MCQs

Practice Set 57 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 1121

Topic: 2. Trauma
A 30-year-old male sustains a vertically oriented, displaced femoral neck fracture (Pauwels Type III) during a motor vehicle collision. Which of the following fixation constructs provides the greatest biomechanical stability against shear forces for this fracture pattern?
. Three parallel partially threaded cannulated screws
. Sliding hip screw with a supplemental derotation screw
. Dynamic condylar screw
. Fully threaded cancellous screws in an inverted triangle configuration
. Unipolar hemiarthroplasty

Correct Answer & Explanation

. Sliding hip screw with a supplemental derotation screw

Explanation

Pauwels Type III fractures are highly vertical and subjected to significant shear forces. A fixed-angle device, such as a sliding hip screw combined with a derotation screw, provides superior biomechanical stability compared to parallel cannulated screws.

Question 1122

Topic: 2. Trauma

A 25-year-old male is admitted with a closed midshaft tibia fracture. Overnight, he complains of severe, escalating pain that is poorly controlled with opioids. Pain is exacerbated by passive stretch of the hallux. What is the accepted delta pressure threshold below which acute compartment syndrome is diagnosed and fasciotomy is indicated?

. 10 mmHg
. 20 mmHg
. 30 mmHg
. 45 mmHg
. 60 mmHg

Correct Answer & Explanation

. 30 mmHg

Explanation

Acute compartment syndrome is generally diagnosed when the delta pressure (diastolic blood pressure minus intracompartmental pressure) is less than 30 mmHg. Relying on an absolute pressure threshold is less accurate due to variations in patient hemodynamics.

Question 1123

Topic: 2. Trauma
A 40-year-old male sustains a Gustilo-Anderson Type IIIB open tibia fracture in a farming accident. Regarding the prevention of deep soft tissue and bone infection, what is the single most critical, time-dependent intervention?
. Time to definitive surgical debridement in the operating room
. Time to skeletal stabilization with an external fixator
. Time to initial administration of systemic antibiotics
. Use of high-pressure pulsatile lavage over gravity irrigation
. Time to definitive soft tissue coverage

Correct Answer & Explanation

. Time to initial administration of systemic antibiotics

Explanation

Multiple studies and guidelines have demonstrated that the time from injury to the initial administration of intravenous antibiotics is the most critical factor in reducing infection rates in open fractures. Delaying antibiotics significantly increases infection risk.

Question 1124

Topic: 2. Trauma

A 22-year-old male presents with a closed oblique fracture of the distal third of the humeral shaft (Holstein-Lewis fracture). On examination, he is unable to extend his wrist or digits but has intact sensation in the median and ulnar distributions. What is the most appropriate initial management?

. Immediate surgical exploration of the radial nerve
. Immediate open reduction and internal fixation of the humerus
. Functional bracing and observation for nerve recovery
. Corticosteroid injection into the radial tunnel
. Application of a bridging external fixator

Correct Answer & Explanation

. Functional bracing and observation for nerve recovery

Explanation

A primary radial nerve palsy associated with a closed humeral shaft fracture does not routinely require immediate surgical exploration. The standard of care is functional bracing and observation, as over 70% of these palsies will spontaneously recover.

Question 1125

Topic: 2. Trauma

A 24-year-old multiply injured patient sustains bilateral femur fractures and a severe blunt chest injury. In deciding between Damage Control Orthopedics (DCO) and Early Total Care (ETC), which of the following laboratory values most strongly indicates the need to proceed with DCO (external fixation)?

. Serum lactate greater than 4.0 mmol/L
. Arterial pH of 7.35
. Core body temperature of 36.5 degrees Celsius
. Platelet count of 150,000/microL
. Base deficit of 1.5 mEq/L

Correct Answer & Explanation

. Serum lactate greater than 4.0 mmol/L

Explanation

Elevated serum lactate (>2.5 to 4.0 mmol/L) or a base deficit greater than 6 mEq/L indicates ongoing hypoperfusion and a state of shock. These borderline or unstable patients should undergo Damage Control Orthopedics to minimize the physiologic hit of prolonged surgery.

Question 1126

Topic: 2. Trauma

A 35-year-old man sustains a severe Schatzker VI tibial plateau fracture. During closed reduction, anterior leg compartmental pressures measure 35 mmHg, while his diastolic blood pressure is 60 mmHg. What is the most appropriate next step?

. Immediate four-compartment fasciotomy
. Observation with serial clinical exams
. Administration of IV mannitol
. Measurement of posterior compartment pressures
. Elevation of the leg above the heart

Correct Answer & Explanation

. Immediate four-compartment fasciotomy

Explanation

A delta pressure (diastolic blood pressure minus compartment pressure) of less than 30 mmHg is an absolute indication for immediate fasciotomy. This patient's delta pressure is 25 mmHg, diagnosing acute compartment syndrome.

Question 1127

Topic: 2. Trauma
A 25-year-old male sustains a vertically displaced (Pauwels type III) femoral neck fracture in a motor vehicle collision. Which of the following fixation constructs provides the most biomechanical stability for this specific fracture pattern?
. Three parallel cancellous screws
. Dynamic hip screw with a derotational screw
. Cephalomedullary nail
. Hemiarthroplasty
. Total hip arthroplasty

Correct Answer & Explanation

. Dynamic hip screw with a derotational screw

Explanation

A sliding hip screw (dynamic hip screw) combined with a derotational screw provides superior biomechanical stability against vertical shear forces. This makes it superior to parallel cancellous screws for highly vertical Pauwels type III fractures.

Question 1128

Topic: Pelvic & Acetabular Trauma

A 40-year-old male presents in hypotensive shock after a crush injury. Pelvic radiographs show a 3 cm symphyseal diastasis and anterior widening of the sacroiliac joints (APC II). What is the primary ligamentous injury responsible for rotational instability?

. Posterior sacroiliac ligaments
. Anterior sacroiliac ligaments
. Sacrotuberous and sacrospinous ligaments
. Iliolumbar ligaments
. Sacroiliac interosseous ligaments

Correct Answer & Explanation

. Sacrotuberous and sacrospinous ligaments

Explanation

In an APC II pelvic ring injury, the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments are disrupted, causing rotational instability. The posterior sacroiliac ligaments remain intact, preserving vertical stability.

Question 1129

Topic: 2. Trauma
A 28-year-old male sustains a Gustilo-Anderson Type IIIB open tibial shaft fracture with massive soft tissue stripping. Intramedullary nailing and debridement are performed. Within what time frame should soft tissue coverage optimally be achieved?
. Within 24 hours
. Within 3 to 7 days
. Within 14 to 21 days
. After 4 weeks when granulation tissue is present
. Delayed primarily at 6 weeks

Correct Answer & Explanation

. Within 3 to 7 days

Explanation

Soft tissue coverage of Type IIIB open tibia fractures should optimally be performed within 3 to 7 days. Delaying coverage beyond 7 days significantly increases the risk of deep infection and flap failure.

Question 1130

Topic: 2. Trauma

A 22-year-old male is admitted with bilateral femur fractures. On hospital day 2, he develops confusion, petechiae on his axillae, and hypoxemia. What is the most critical initial management for this complication?

. Administration of high-dose corticosteroids
. Immediate surgical fixation of all fractures
. Heparin anticoagulation
. Supportive care including adequate oxygenation and ventilation
. Administration of broad-spectrum intravenous antibiotics

Correct Answer & Explanation

. Supportive care including adequate oxygenation and ventilation

Explanation

The patient is exhibiting classic signs of fat embolism syndrome. The mainstay of treatment is supportive care, primarily consisting of aggressive respiratory support and maintaining adequate oxygenation.

Question 1131

Topic: Pelvic & Acetabular Trauma
A 35-year-old male is brought in after a high-speed motor vehicle collision. Radiographs demonstrate an anteroposterior compression (APC) pelvic ring injury. Which of the following ligaments must be disrupted to classify this as an APC III rather than an APC II injury?
. Anterior sacroiliac ligament
. Sacrotuberous ligament
. Sacrospinous ligament
. Posterior sacroiliac ligament
. Iliolumbar ligament

Correct Answer & Explanation

. Posterior sacroiliac ligament

Explanation

An APC II injury involves disruption of the pubic symphysis, anterior SI, sacrotuberous, and sacrospinous ligaments. An APC III injury implies complete hemipelvis instability, necessitating the additional disruption of the strong posterior SI ligaments.

Question 1132

Topic: 2. Trauma

A 40-year-old male sustains a coronal plane fracture of the lateral femoral condyle (Hoffa fracture). When fixing this fracture with lag screws, which screw trajectory provides the greatest biomechanical stability?

. Anterior-to-posterior
. Posterior-to-anterior
. Lateral-to-medial
. Medial-to-lateral
. Inferior-to-superior

Correct Answer & Explanation

. Posterior-to-anterior

Explanation

Posterior-to-anterior (PA) lag screw placement is biomechanically superior to anterior-to-posterior placement for Hoffa fractures. PA screws better resist primary deforming forces and secure the dense posterior cortical bone against the anterior fragment.

Question 1133

Topic: 2. Trauma

A 35-year-old male is admitted with a highly comminuted tibial shaft fracture. His blood pressure is 110/70 mmHg. He develops out-of-proportion pain and paresthesias in the first web space. What is the absolute threshold of compartment pressure parameters at which fasciotomy is unequivocally indicated?

. Absolute compartment pressure > 30 mmHg
. Absolute compartment pressure > 40 mmHg
. Differential pressure (Diastolic BP - compartment pressure) < 30 mmHg
. Differential pressure (Mean Arterial Pressure - compartment pressure) < 40 mmHg
. Differential pressure (Systolic BP - compartment pressure) < 30 mmHg

Correct Answer & Explanation

. Differential pressure (Diastolic BP - compartment pressure) < 30 mmHg

Explanation

Compartment syndrome is most accurately diagnosed using the delta pressure, calculated as diastolic blood pressure minus compartment pressure. A delta pressure of less than 30 mmHg is the accepted and most reliable threshold indicating the need for emergent fasciotomy.

Question 1134

Topic: Lower Extremity Trauma

During a posteromedial approach for fixation of a Schatzker IV tibial plateau fracture, the primary surgical interval is developed between the medial head of the gastrocnemius and which of the following structures?

. Soleus
. Popliteus
. Pes anserinus
. Biceps femoris
. Tibialis posterior

Correct Answer & Explanation

. Pes anserinus

Explanation

The standard posteromedial approach to the tibial plateau utilizes the interval between the medial head of the gastrocnemius (retracted laterally) and the pes anserinus (retracted medially). This provides direct, safe access to the posteromedial articular fragment.

Question 1135

Topic: 2. Trauma

When performing an extensile lateral approach for a displaced intra-articular calcaneus fracture, the viability of the full-thickness soft tissue flap relies primarily on blood supply from which of the following arteries?

. Dorsalis pedis artery
. Medial plantar artery
. Lateral plantar artery
. Lateral calcaneal artery
. Sural artery

Correct Answer & Explanation

. Lateral calcaneal artery

Explanation

The extensile lateral flap for calcaneus fractures relies entirely on the lateral calcaneal artery, a terminal branch of the peroneal artery. Creating a subperiosteal, "no-touch" full-thickness flap is critical to preserve this fragile blood supply.

Question 1136

Topic: Pelvic & Acetabular Trauma
A 45-year-old male presents to the emergency department after a high-energy motor vehicle accident. He has a comminuted pelvic ring injury involving the pubic symphysis and right sacroiliac joint, classified as an APC III. On initial evaluation, he is hypotensive, tachycardic, and has gross hematuria with a high-riding prostate on digital rectal examination. What is the most appropriate initial management step for his suspected urological injury after initial resuscitation?
. Perform a Foley catheter insertion immediately.
. Proceed directly to open surgical exploration for bladder repair.
. Obtain an intravenous pyelogram (IVP) to assess renal function.
. Perform a retrograde urethrogram (RUG) prior to any urethral instrumentation.
. Insert a suprapubic catheter if Foley catheterization is unsuccessful.

Correct Answer & Explanation

. Perform a retrograde urethrogram (RUG) prior to any urethral instrumentation.

Explanation

The patient's presentation with a high-energy pelvic fracture, gross hematuria, and a high-riding prostate strongly suggests a posterior urethral injury. In such cases, urethral instrumentation with a Foley catheter is contraindicated until a retrograde urethrogram (RUG) has been performed to rule out or characterize the urethral injury. Attempting to insert a Foley catheter blindly can convert a partial tear into a complete tear or create a false passage, worsening the injury. If a urethral injury is confirmed and Foley insertion is not possible, a suprapubic catheter is the preferred method for bladder drainage.

Question 1137

Topic: 2. Trauma

A 35-year-old male presents with a T10 burst fracture after a fall from height. He has a neurological deficit corresponding to an ASIA C injury. Initial assessment reveals stable vital signs but diminished breath sounds at the lung bases. What is the most critical immediate respiratory concern related to a T10 spinal cord injury?

. Phrenic nerve paralysis leading to diaphragmatic dysfunction.
. Intercostal muscle weakness impacting effective cough and deep breathing.
. Bronchospasm due to sympathetic nervous system dysregulation.
. Acute respiratory distress syndrome (ARDS).
. Massive hemothorax from associated rib fractures.

Correct Answer & Explanation

. Intercostal muscle weakness impacting effective cough and deep breathing.

Explanation

Correct Answer: BA T10 spinal cord injury typically spares the phrenic nerve (C3-C5), so diaphragmatic function is generally preserved. However, the intercostal muscles, innervated by T1-T11, are significantly weakened or paralyzed at this level. This compromises the patient's ability to take deep breaths and effectively clear secretions through coughing, leading to atelectasis, pneumonia, and hypoventilation. While other respiratory issues can occur, intercostal muscle weakness is the most direct and common respiratory complication of a thoracic spinal cord injury at this level. Phrenic nerve paralysis is seen with higher cervical injuries. Bronchospasm, ARDS, and hemothorax are less directly and universally linked to a T10 SCI itself in this scenario without further evidence.

Question 1138

Topic: 2. Trauma

A 22-year-old male sustains a right-sided scapular fracture and multiple concomitant rib fractures (ribs 4-8) after a motorcycle collision. He is hypotensive, tachycardic, and has paradoxical chest wall motion on the right. Auscultation reveals absent breath sounds on the right. What is the most immediate life-threatening thoracic injury that requires urgent intervention?

. Simple pneumothorax.
. Flail chest.
. Pulmonary contusion.
. Tension pneumothorax.
. Hemothorax.

Correct Answer & Explanation

. Tension pneumothorax.

Explanation

Correct Answer: DThe patient's presentation with hypotension, tachycardia, absent breath sounds on the right, and paradoxical chest wall motion (suggesting flail chest) in the setting of severe trauma points to a tension pneumothorax as the most immediate life-threatening thoracic injury. Flail chest itself is a severe injury causing paradoxical motion and impaired ventilation, and pulmonary contusion causes respiratory compromise, but a tension pneumothorax rapidly compromises venous return to the heart and lung function, leading to shock. A simple pneumothorax or hemothorax might present with absent breath sounds but typically without the profound hemodynamic instability and mediastinal shift characteristic of tension pneumothorax. A tension pneumothorax requires immediate needle decompression followed by chest tube insertion.

Question 1139

Topic: 2. Trauma

A 30-year-old male presents after a severe fall, sustaining multiple rib fractures and a displaced sternal fracture. His chest X-ray shows a widened mediastinum and CT reveals a suspicious finding adjacent to the aorta. What is the most critical immediate concern regarding the sternal fracture?

. Pneumothorax.
. Hemothorax.
. Cardiac contusion.
. Tracheal injury.
. Aortic injury.

Correct Answer & Explanation

. Aortic injury.

Explanation

Correct Answer: EWhile cardiac contusion is a significant concern with sternal fractures, and pneumothorax/hemothorax can occur with rib fractures, a widened mediastinum on chest X-ray in the context of high-energy trauma strongly suggests a major vascular injury, particularly to the aorta. A displaced sternal fracture, especially when combined with a widened mediastinum, increases the suspicion for an aortic injury. This is an immediate life-threatening condition requiring urgent diagnosis and intervention. Tracheal injury is possible but less likely to present with a widened mediastinum compared to aortic injury.

Question 1140

Topic: 2. Trauma

Which of the following factors is considered the MOST detrimental to fracture healing, significantly increasing the risk of non-union?

. Patient age over 60 years
. Presence of diabetes mellitus
. Smoking history
. Severe fracture comminution
. Inadequate mechanical stability at the fracture site

Correct Answer & Explanation

. Inadequate mechanical stability at the fracture site

Explanation

Correct Answer: EWhile all listed options can negatively impact fracture healing, inadequate mechanical stability at the fracture site is considered the MOST detrimental factor leading to non-union. Bone healing requires a stable environment to progress through its stages. Excessive motion at the fracture site (micromotion beyond an optimal range) disrupts callus formation, prevents vascular ingrowth, and can lead to the formation of fibrous tissue or pseudarthrosis instead of bone. Patient age, diabetes, smoking, and severe comminution are significant risk factors, but they often exert their effect by impairing the biological capacity for healing, which is then exacerbated by poor mechanical conditions.

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