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2. Trauma MCQs

Practice Set 306 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 6101

Topic: 2. Trauma
In a hemodynamically unstable patient with a high-energy Anteroposterior Compression (APC) Type III pelvic ring injury, what is the most common anatomical source of the life-threatening retroperitoneal hemorrhage?
. Superior gluteal artery
. Internal iliac artery main trunk
. Venous presacral plexus and cancellous bone surfaces
. Corona mortis
. External iliac vein

Correct Answer & Explanation

. Venous presacral plexus and cancellous bone surfaces

Explanation

While arterial bleeding (e.g., from branches of the internal iliac like the superior gluteal or internal pudendal arteries) can cause rapid demise, 80-90% of pelvic hemorrhage in pelvic ring disruptions originates from venous sources (presacral plexus) and the exposed cancellous bone surfaces at fracture sites.

Question 6102

Topic: 2. Trauma

A 45-year-old male sustains a high-energy Schatzker IV (medial) tibial plateau fracture. Advanced imaging reveals a large coronal shear fragment of the posteromedial plateau. Which surgical approach is specifically indicated to directly visualize and buttress this specific fragment?

. Standard anterolateral approach
. Medial parapatellar approach
. Posteromedial approach
. Posterolateral approach
. Direct anterior approach

Correct Answer & Explanation

. Posteromedial approach

Explanation

A posteromedial shear fragment is a classic component of complex medial tibial plateau fractures (and often missed Schatzker IV or fracture-dislocations). Anterior approaches cannot adequately expose or reduce this fragment. A posteromedial approach (often passing between the medial head of the gastrocnemius and the pes anserinus) is required to apply a posterior buttress plate, neutralizing the vertical shear forces exerted during knee flexion.

Question 6103

Topic: 2. Trauma

In the diagnosis of acute compartment syndrome using continuous intra-compartmental pressure monitoring, which of the following criteria is the most accurate indicator for performing a fasciotomy?

. Absolute compartment pressure > 20 mmHg
. Absolute compartment pressure > 30 mmHg
. Diastolic blood pressure minus compartment pressure (Delta P) < 30 mmHg
. Mean arterial pressure minus compartment pressure < 40 mmHg
. Systolic blood pressure minus compartment pressure < 50 mmHg

Correct Answer & Explanation

. Diastolic blood pressure minus compartment pressure (Delta P) < 30 mmHg

Explanation

The Delta pressure (Diastolic Blood Pressure - Compartment Pressure) is the most reliable parameter for diagnosing acute compartment syndrome. A Delta pressure of less than 30 mmHg indicates inadequate capillary perfusion to the muscle and mandates emergent fasciotomy. Absolute pressure thresholds (e.g., >30 mmHg) are less reliable as they do not account for variations in systemic blood pressure.

Question 6104

Topic: 2. Trauma
A 30-year-old male sustains a vertically oriented, displaced femoral neck fracture (Pauwels Type III). Operative fixation is planned. Which of the following internal fixation constructs provides the greatest biomechanical stability against shear forces for this specific fracture pattern?
. Three parallel cancellous screws in an inverted triangle
. Three parallel cancellous screws with a fourth off-axis screw
. A sliding hip screw (SHS) with a supplemental derotational cancellous screw
. A dynamic condylar screw (DCS)
. Two parallel fully threaded cortical screws

Correct Answer & Explanation

. A sliding hip screw (SHS) with a supplemental derotational cancellous screw

Explanation

Pauwels Type III femoral neck fractures have a high shear angle (>50 degrees), making them highly unstable and prone to varus collapse and nonunion. Biomechanical studies (e.g., Aminian et al., Liporace et al.) have demonstrated that a sliding hip screw with a supplemental derotational screw provides superior biomechanical stability against shear forces and varus collapse compared to multiple cancellous screws in these vertically oriented young adult fractures.

Question 6105

Topic: 2. Trauma

A 24-year-old professional football player sustains a twisting injury to his left knee. Radiographs reveal an elliptic avulsion fracture of the anterolateral proximal tibia (Segond fracture). This radiographic finding represents a bony avulsion of which of the following capsuloligamentous structures?

. Iliotibial band
. Biceps femoris tendon
. Anterolateral ligament (ALL) and lateral capsular ligament
. Lateral collateral ligament (LCL)
. Popliteofibular ligament

Correct Answer & Explanation

. Anterolateral ligament (ALL) and lateral capsular ligament

Explanation

A Segond fracture is a cortical avulsion fracture off the anterolateral aspect of the proximal tibia and is highly pathognomonic for an anterior cruciate ligament (ACL) tear. Anatomical studies have shown that it represents an avulsion of the anterolateral ligament (ALL) and the lateral capsular ligament. It is not an avulsion of the IT band (which attaches at Gerdy's tubercle) or the biceps femoris/LCL (which attach to the fibular head).

Question 6106

Topic: Pelvic & Acetabular Trauma
A 40-year-old male is brought to the trauma bay in hemorrhagic shock following a motorcycle accident. Radiographs reveal an Anteroposterior Compression Type III (APC-III) pelvic ring injury. According to the Young and Burgess classification, which of the following ligamentous structures are completely disrupted in this specific injury pattern?
. Symphyseal ligaments and anterior sacroiliac ligaments only
. Symphyseal, sacrospinous, and sacrotuberous ligaments only
. Symphyseal, sacrospinous, sacrotuberous, and anterior sacroiliac ligaments
. Symphyseal, sacrospinous, sacrotuberous, anterior sacroiliac, and posterior sacroiliac ligaments
. Symphyseal and iliolumbar ligaments only

Correct Answer & Explanation

. Symphyseal, sacrospinous, sacrotuberous, anterior sacroiliac, and posterior sacroiliac ligaments

Explanation

An APC-III pelvic fracture represents complete global instability (a 'completely open book' pelvis). It involves disruption of the anterior structures (symphyseal ligaments) and a complete disruption of the posterior pelvic floor and arch, including the sacrospinous, sacrotuberous, anterior sacroiliac, and posterior sacroiliac ligaments. This allows the hemipelvis to separate completely from the sacrum.

Question 6107

Topic: Lower Extremity Trauma

A 42-year-old male sustains a high-energy Schatzker Type IV tibial plateau fracture with a significant posteromedial shear fragment. Surgical fixation requires a posteromedial approach to the knee. The optimal intermuscular interval for this approach is developed between the medial head of the gastrocnemius posteriorly and which of the following structures anteriorly?

. Soleus muscle
. Semimembranosus tendon
. Pes anserinus tendons (Sartorius, Gracilis, Semitendinosus)
. Popliteus muscle
. Flexor hallucis longus muscle

Correct Answer & Explanation

. Pes anserinus tendons (Sartorius, Gracilis, Semitendinosus)

Explanation

The classic posteromedial approach to the tibial plateau utilizes the interval between the medial head of the gastrocnemius (which is retracted posteriorly/laterally to protect the neurovascular bundle) and the pes anserinus tendons (Sartorius, Gracilis, Semitendinosus), which are retracted anteriorly. This safely exposes the posteromedial metaphysis of the proximal tibia for anti-glide plating.

Question 6108

Topic: 2. Trauma

A 65-year-old female sustains a displaced 3-part proximal humerus fracture. Based on current anatomical studies, which of the following vascular structures provides the primary blood supply to the humeral head and is critical to evaluate for avascular necrosis risk?

. Anterior humeral circumflex artery
. Arcuate artery
. Posterior humeral circumflex artery
. Thoracoacromial artery
. Subscapular artery

Correct Answer & Explanation

. Posterior humeral circumflex artery

Explanation

Historically, the anterior humeral circumflex artery (via the arcuate branch) was considered the main vascular supply to the humeral head. However, modern quantitative studies (e.g., Hettrich et al.) have proven that the posterior humeral circumflex artery is the principal blood supply, providing approximately 64% of the blood flow to the humeral head.

Question 6109

Topic: 2. Trauma

A 75-year-old male sustains a Type II odontoid fracture after a ground-level fall. He is neurologically intact. Non-operative management with a rigid cervical orthosis is being considered. Which of the following factors is associated with the highest risk of nonunion if treated non-operatively?

. Initial fracture displacement > 5 mm
. Patient age less than 40 years
. Fracture gap < 1 mm
. Concomitant C1 posterior arch fracture
. Anterior displacement rather than posterior displacement

Correct Answer & Explanation

. Initial fracture displacement > 5 mm

Explanation

Risk factors for nonunion of a Type II odontoid fracture treated non-operatively include initial displacement > 5 mm, angulation > 11 degrees, patient age > 50 years, and posterior displacement. Displacement > 5 mm significantly decreases the likelihood of successful union with a halo or rigid collar, often prompting consideration for primary surgical stabilization.

Question 6110

Topic: Pelvic & Acetabular Trauma
A 30-year-old male is brought to the trauma bay hypotensive after a motorcycle crash. A pelvic binder is applied. Radiographs show a widened pubic symphysis (3.5 cm) and disrupted anterior and posterior sacroiliac ligaments (APC III). Hemodynamic instability in this injury is primarily caused by bleeding from which of the following sources?
. Presacral venous plexus
. Internal pudendal artery
. Superior gluteal artery
. Corona mortis
. External iliac vein

Correct Answer & Explanation

. Presacral venous plexus

Explanation

In pelvic ring injuries (especially Anteroposterior Compression III types), 80-90% of significant hemorrhage is venous in origin, most commonly from the presacral venous plexus and prevesical veins. While arterial bleeding (e.g., superior gluteal artery in lateral compression, pudendal in APC) can occur and is life-threatening, massive venous bleeding secondary to pelvic volume expansion is the most frequent cause of hemodynamic instability.

Question 6111

Topic: 2. Trauma
A 30-year-old male sustains a 'floating knee' injury following a severe motor vehicle collision. Radiographs demonstrate a fracture of the distal femur with intra-articular extension into the knee, combined with an extra-articular diaphyseal fracture of the ipsilateral tibia. According to the Fraser classification, what type of floating knee is this?
. Type I
. Type IIA
. Type IIB
. Type IIC
. Type III

Correct Answer & Explanation

. Type IIA

Explanation

The Fraser classification for floating knee injuries is based on intra-articular involvement: Type I implies both the femur and tibia fractures are extra-articular (diaphyseal). Type IIA is an intra-articular fracture of the distal femur and an extra-articular fracture of the tibia. Type IIB is an extra-articular femur with an intra-articular tibia. Type IIC involves intra-articular fractures of both the femur and the tibia.

Question 6112

Topic: Pelvic & Acetabular Trauma

A 45-year-old male sustains an LC-II pelvic ring injury (crescent fracture) after a motor vehicle accident. Which of the following best describes the pathomechanics and optimal fixation of this specific injury?

. External rotation force causing SI joint disruption; anterior symphyseal plating
. Internal rotation force fracturing the posterior ilium leaving the SI ligaments attached to the fragment; ORIF of the ilium
. Vertical shear force causing complete pelvic floor disruption; spinopelvic fixation
. Internal rotation force avulsing the sacrotuberous ligament; percutaneous SI screws
. External rotation force causing pubic symphysis diastasis >2.5cm; anterior and posterior plating

Correct Answer & Explanation

. Internal rotation force fracturing the posterior ilium leaving the SI ligaments attached to the fragment; ORIF of the ilium

Explanation

An LC-II (crescent fracture) is caused by a lateral compression (internal rotation) force. It results in a fracture of the posterior ilium. The strong posterior sacroiliac (SI) ligaments remain attached to the crescent-shaped posterior iliac fragment, leaving the SI joint intact. Treatment typically involves Open Reduction and Internal Fixation (ORIF) of the ilium rather than an SI screw, because the SI joint itself is not dislocated.

Question 6113

Topic: 2. Trauma
A 30-year-old male sustains a vertical femoral neck fracture (Pauwels Type III, 70-degree angle) following a fall from height. Which of the following fixation constructs offers the greatest biomechanical stability against the predominant deforming shear forces?
. Three parallel cancellous screws placed in an inverted triangle configuration
. A dynamic hip screw (sliding hip screw) combined with a derotational cancellous screw
. Two parallel 7.3 mm cannulated screws
. A fully threaded solid intramedullary nail
. Non-operative management with skeletal traction

Correct Answer & Explanation

. A dynamic hip screw (sliding hip screw) combined with a derotational cancellous screw

Explanation

Pauwels Type III fractures are highly vertical and experience massive shear forces, leading to high rates of nonunion and varus collapse. Biomechanical studies have demonstrated that a fixed-angle device, such as a sliding hip screw (dynamic hip screw), combined with an anti-rotation screw provides superior resistance to shear forces and a more stable construct than multiple parallel cancellous screws for vertical neck fractures in young adults.

Question 6114

Topic: 2. Trauma

A 32-year-old male is admitted with a comminuted tibia fracture. He develops increasing pain out of proportion to the injury. His blood pressure is 110/70 mmHg. Intracompartmental pressure monitoring of the anterior compartment yields a pressure of 45 mmHg. What is his Delta P, and what is the indicated management?

. Delta P is 65 mmHg; continue elevation and observation
. Delta P is 25 mmHg; emergent four-compartment fasciotomy
. Delta P is 25 mmHg; administer IV mannitol and hyperbaric oxygen
. Delta P is 35 mmHg; observation
. Delta P is -35 mmHg; immediate amputation

Correct Answer & Explanation

. Delta P is 25 mmHg; emergent four-compartment fasciotomy

Explanation

Delta P is calculated as Diastolic Blood Pressure minus Compartment Pressure (70 - 45 = 25 mmHg). A Delta P of less than 30 mmHg (or an absolute compartment pressure within 30 mmHg of the diastolic pressure) is the widely accepted threshold indicating acute compartment syndrome, which mandates emergent fasciotomy.

Question 6115

Topic: 2. Trauma

A 35-year-old unrestrained driver is involved in a motor vehicle collision. Radiographs and CT imaging reveal an intra-articular distal femur fracture with a separate, displaced fracture of the posterior aspect of the lateral femoral condyle. This posterior condylar fracture (Hoffa fracture) occurs most commonly in which plane?

. Axial plane
. Sagittal plane
. Coronal plane
. Transverse plane
. Oblique plane

Correct Answer & Explanation

. Coronal plane

Explanation

A Hoffa fracture is a tangential, unicondylar fracture of the posterior aspect of the distal femur. It occurs classically in the coronal plane. It is often missed on plain AP and lateral radiographs and usually requires a CT scan for accurate diagnosis and surgical planning. Fixation generally involves anterior-to-posterior or posterior-to-anterior lag screws.

Question 6116

Topic: 2. Trauma

Which of the following calcium-based bone graft substitutes possesses the highest compressive strength but has the slowest rate of resorption in vivo?

. Calcium sulfate
. Calcium phosphate
. Tricalcium phosphate
. Demineralized bone matrix
. Cancellous allograft

Correct Answer & Explanation

. Calcium phosphate

Explanation

Calcium phosphate cements have the highest compressive strength among the common synthetic bone graft substitutes, making them useful for filling metaphyseal voids where structural support is temporarily needed (e.g., tibial plateau fractures). However, they are resorbed very slowly by osteoclasts (months to years). Calcium sulfate resorbs very rapidly (4-8 weeks) but has low structural strength. Tricalcium phosphate has intermediate properties.

Question 6117

Topic: 2. Trauma

A 'floating shoulder' injury consists of ipsilateral fractures of the clavicular shaft and the scapular neck. Surgical fixation of the clavicle is often recommended to stabilize the shoulder girdle. Which of the following criteria is an absolute indication for operative fixation of the scapula body/neck in this scenario?

. Medialization of the glenoid > 5 mm
. Glenoid polar angle (GPA) < 20 degrees
. Scapular neck angulation > 40 degrees
. Presence of a concomitant hemopneumothorax
. Fracture of the coracoid process

Correct Answer & Explanation

. Glenoid polar angle (GPA) < 20 degrees

Explanation

Operative indications for scapular neck fractures (with or without a clavicle fracture) include a Glenoid Polar Angle (GPA) of < 20 degrees (normal is 30-45 degrees), medialization of the glenoid > 20 mm (not 5 mm), and angular deformity > 40 degrees. A GPA < 20 degrees severely alters the rotator cuff biomechanics and represents a strong indication for ORIF.

Question 6118

Topic: 2. Trauma

Recombinant human bone morphogenetic proteins (rhBMPs) are utilized in orthopedics to promote bone healing. Which specific rhBMP is currently FDA-approved as an adjunct to intramedullary nail fixation for acute, open tibial shaft fractures?

. rhBMP-2
. rhBMP-3
. rhBMP-4
. rhBMP-7
. rhBMP-9

Correct Answer & Explanation

. rhBMP-2

Explanation

rhBMP-2 (Infuse) is FDA-approved for acute open tibial shaft fractures treated with an intramedullary nail (within 14 days of injury), as well as for anterior lumbar interbody fusion (ALIF). rhBMP-7 (OP-1) was previously approved under a humanitarian device exemption for recalcitrant tibial nonunions, not acute fractures. BMP-3 actually inhibits osteogenesis.

Question 6119

Topic: 2. Trauma
A 22-year-old male suffers a highly comminuted closed tibia fracture. In the emergency department, he complains of severe pain out of proportion to the injury. The clinical exam is equivocal for compartment syndrome. You decide to measure intracompartmental pressures. What is the generally accepted threshold defining the critical 'delta P' that indicates a need for emergency fasciotomy?
. Systolic Blood Pressure - Compartment Pressure < 30 mmHg
. Diastolic Blood Pressure - Compartment Pressure < 30 mmHg
. Mean Arterial Pressure - Compartment Pressure < 30 mmHg
. Absolute Compartment Pressure > 30 mmHg
. Absolute Compartment Pressure > 45 mmHg

Correct Answer & Explanation

. Diastolic Blood Pressure - Compartment Pressure < 30 mmHg

Explanation

The delta P (ΔP) is calculated as the Diastolic Blood Pressure minus the Intracompartmental Pressure. A ΔP of less than 30 mmHg signifies that the tissue perfusion pressure is inadequate, and it is the most reliable threshold for diagnosing acute compartment syndrome and indicating the need for emergency fasciotomy. Absolute pressure measurements are less reliable as they do not account for patient hypotension.

Question 6120

Topic: Pelvic & Acetabular Trauma
A 35-year-old male arrives at the trauma bay with hemodynamic instability following a crush injury to the pelvis. AP pelvis radiograph demonstrates an anteroposterior compression (APC III) injury with an "open book" pelvic ring disruption. A pelvic binder is ordered. To most effectively reduce the pelvic volume and provide a tamponade effect, the binder should be centered precisely over which of the following anatomic landmarks?
. Iliac crests
. Anterior superior iliac spines
. Greater trochanters
. Symphysis pubis
. Sacral promontory

Correct Answer & Explanation

. Greater trochanters

Explanation

Pelvic binders and sheets are most effective at reducing pelvic volume and closing an "open book" pelvic ring disruption when they are centered over the greater trochanters. A common error is placing the binder too high over the iliac crests, which is mechanically inferior and can inadvertently force the inferior aspect of the pelvis wider.

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