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2. Trauma MCQs

Practice Set 307 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 6121

Topic: 2. Trauma

A 22-year-old male is diagnosed with a displaced fracture of the proximal pole of the scaphoid. He is informed that this specific fracture pattern carries a high risk of avascular necrosis and nonunion. What anatomical feature of the scaphoid's blood supply accounts for this vulnerability?

. The blood supply is purely intraosseous with no periosteal contributions
. The entire blood supply enters distally and flows in a retrograde fashion to the proximal pole
. The proximal pole relies exclusively on end-arteries branching from the ulnar artery
. The major blood supply enters via the scapholunate interosseous ligament
. The scaphoid relies heavily on synovial fluid diffusion for nutrient transport

Correct Answer & Explanation

. The entire blood supply enters distally and flows in a retrograde fashion to the proximal pole

Explanation

The major blood supply to the scaphoid is derived from the radial artery, primarily via the dorsal carpal branch. The vessels enter the scaphoid at the distal pole and dorsal ridge, flowing in a retrograde direction to supply the proximal pole. Because the blood supply travels from distal to proximal, a fracture across the waist or proximal pole severs the blood supply to the proximal fragment, leading to a high rate of avascular necrosis and nonunion.

Question 6122

Topic: 2. Trauma
A 28-year-old male presents with a femoral neck fracture sustained in a fall from height. Radiographs show a vertically oriented fracture line with an angle of 75 degrees relative to the horizontal (Pauwels Type III). He undergoes urgent surgical fixation. Biomechanically, what is the most appropriate fixation construct to neutralize the predominantly high shear forces in this fracture pattern?
. Three parallel cannulated screws placed in an inverted triangle
. Two parallel cannulated screws
. A sliding hip screw (SHS) with an anti-rotation screw or a proximal femoral locking plate
. A partially threaded cancellous screw and a cerclage wire
. Dynamic condylar screw (DCS) inserted retrograde

Correct Answer & Explanation

. A sliding hip screw (SHS) with an anti-rotation screw or a proximal femoral locking plate

Explanation

Pauwels Type III femoral neck fractures are vertically oriented (>50 degrees), which subjects the fracture site to high shear forces and varus displacing moments, leading to higher failure rates with traditional parallel cannulated screws. Biomechanical studies indicate that fixed-angle constructs, such as a sliding hip screw (SHS) combined with an anti-rotation screw, or a proximal femoral locking plate, provide significantly greater stability against shear forces and are preferred for this vertical fracture pattern in young adults.

Question 6123

Topic: 2. Trauma
A 25-year-old male sustains a high-energy Pauwels type III femoral neck fracture. Based on biomechanical studies of vertical femoral neck fractures, which of the following internal fixation constructs demonstrates the highest ultimate failure load against shear forces?
. Three parallel cancellous screws placed in an inverted triangle
. A sliding hip screw (SHS) alone
. A sliding hip screw (SHS) augmented with an anti-rotation cancellous screw
. A dynamic condylar screw
. A proximal femoral locking plate

Correct Answer & Explanation

. A sliding hip screw (SHS) augmented with an anti-rotation cancellous screw

Explanation

Pauwels type III femoral neck fractures (fracture angle >50 degrees) experience very high shear forces. Biomechanical studies (such as Aminian et al.) have consistently shown that a fixed-angle sliding hip screw combined with a derotation screw provides superior biomechanical stability and the highest ultimate failure load compared to multiple cancellous screws or a proximal femoral locking plate in vertical fracture patterns.

Question 6124

Topic: 2. Trauma

In the evaluation of a patient with suspected acute compartment syndrome of the lower extremity, which of the following manometric pressure criteria is considered the most reliable threshold for performing a four-compartment fasciotomy?

. Absolute compartment pressure > 20 mm Hg
. Absolute compartment pressure > 30 mm Hg
. Delta P (Diastolic blood pressure - compartment pressure) < 30 mm Hg
. Delta P (Mean arterial pressure - compartment pressure) < 40 mm Hg
. Delta P (Systolic blood pressure - compartment pressure) < 50 mm Hg

Correct Answer & Explanation

. Delta P (Diastolic blood pressure - compartment pressure) < 30 mm Hg

Explanation

Current evidence indicates that the Delta P—calculated as the patient's diastolic blood pressure minus the intracompartmental pressure—is the most reliable indicator for compartment syndrome. A Delta P of less than 30 mm Hg is the widely accepted threshold for surgical intervention (fasciotomy). Relying on absolute pressures alone can lead to overtreatment, particularly in hypertensive patients.

Question 6125

Topic: 2. Trauma

A 28-year-old male sustains a closed, isolated mid-shaft humerus fracture after a fall. In the emergency department, he is noted to have a dense radial nerve palsy that was present immediately following the injury. Radiographs show a displaced Holstein-Lewis type fracture. What is the most appropriate initial management of the radial nerve palsy?

. Immediate surgical exploration and nerve repair
. Application of a coaptation splint and observation
. Electromyography (EMG) to assess nerve continuity
. Closed reduction with forceful manipulation to clear the nerve
. External fixation with distraction histogenesis

Correct Answer & Explanation

. Application of a coaptation splint and observation

Explanation

Primary radial nerve palsy in the setting of a closed humeral shaft fracture (even a Holstein-Lewis distal third spiral fracture) is typically a neuropraxia. The standard of care is conservative management with a coaptation splint or fracture brace and clinical observation. Surgical exploration is indicated for open fractures, associated vascular injury, or if the palsy developsafterclosed reduction (secondary palsy).

Question 6126

Topic: Pelvic & Acetabular Trauma
A 35-year-old male is brought to the trauma bay following a high-speed motorcycle collision. Pelvic radiographs reveal symphyseal diastasis of 3.5 cm and widening of both the anterior and posterior aspects of the sacroiliac joint. Based on the Young-Burgess classification, what injury pattern is present and what is the primary source of life-threatening hemorrhage typically associated with this specific pattern?
. Anteroposterior Compression (APC) Type I; Superior gluteal artery
. Anteroposterior Compression (APC) Type II; Obturator artery
. Anteroposterior Compression (APC) Type III; Venous plexus and internal iliac arterial branches
. Lateral Compression (LC) Type II; Corona mortis
. Vertical Shear; External iliac artery

Correct Answer & Explanation

. Anteroposterior Compression (APC) Type III; Venous plexus and internal iliac arterial branches

Explanation

This is an APC Type III injury, characterized by complete disruption of the pubic symphysis, anterior SI ligaments, interosseous SI ligaments, and posterior SI ligaments (causing complete hemipelvis instability). APC injuries significantly increase pelvic volume and disrupt the pre-sacral venous plexus and anterior branches of the internal iliac artery (e.g., pudendal, obturator), which are the primary sources of massive hemorrhage in these open-book fractures.

Question 6127

Topic: 2. Trauma
A 35-year-old healthy female sustains a displaced femoral neck fracture with a highly vertical fracture line (Pauwels Type III) after a high-energy fall. In selecting the optimal internal fixation construct for this specific fracture pattern to minimize the risk of varus collapse and non-union, biomechanical studies favor which of the following?
. Three parallel cannulated screws placed in an inverted triangle
. Two parallel cannulated screws
. A sliding hip screw (fixed-angle device) with an adjunctive anti-rotation screw
. A cephalomedullary nail with a single lag screw
. Hemiarthroplasty

Correct Answer & Explanation

. A sliding hip screw (fixed-angle device) with an adjunctive anti-rotation screw

Explanation

Pauwels Type III femoral neck fractures possess a highly vertical fracture line (>50 degrees), subjecting them to extreme vertical shear forces. Biomechanical studies have consistently shown that a fixed-angle construct, such as a sliding hip screw (SHS), provides superior resistance to varus collapse and vertical shear compared to multiple parallel cannulated screws in this specific, high-angle fracture pattern. An adjunctive anti-rotation screw is often added above the SHS to control rotation during screw insertion and healing.

Question 6128

Topic: 2. Trauma

A 42-year-old male sustains a severe closed bicondylar tibial plateau fracture (Schatzker VI). Initial management includes a spanning external fixator. During definitive fixation 10 days later via dual incisions, which surgical principle must be strictly adhered to minimize the risk of wound complications?

. Elevate full-thickness fasciocutaneous flaps ensuring a minimum 7 cm skin bridge between incisions
. Perform the posteromedial approach prior to removing the external fixator pins
. Place the anterolateral incision directly over the tibial crest
. Use a single midline incision to expose both condyles simultaneously
. Limit the anterolateral skin bridge to less than 5 cm to ensure adequate visualization

Correct Answer & Explanation

. Elevate full-thickness fasciocutaneous flaps ensuring a minimum 7 cm skin bridge between incisions

Explanation

When performing dual incisions for a bicondylar tibial plateau fracture (typically anterolateral and posteromedial), a minimum skin bridge of 7 to 9 cm must be maintained to preserve the blood supply to the intervening skin and reduce the risk of wound necrosis. Full-thickness fasciocutaneous flaps should be elevated without undermining the subcutaneous tissues.

Question 6129

Topic: Pelvic & Acetabular Trauma
A 30-year-old male is brought to the trauma bay after a motorcycle crash. His blood pressure is 70/40 mmHg, HR 135 bpm. FAST exam is negative. Pelvic radiograph shows an AP Compression Type III (APC-III) pelvic ring injury. A pelvic binder is applied, but the patient remains hemodynamically unstable despite massive transfusion protocol initiation. What is the most appropriate next step in management?
. Immediate open reduction and internal fixation of the symphysis pubis
. Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) or Preperitoneal Pelvic Packing/Angiography
. Exploratory laparotomy and bowel resection
. Application of an external fixator and immediate transfer to the ICU
. Immediate bilateral lower extremity amputations

Correct Answer & Explanation

. Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) or Preperitoneal Pelvic Packing/Angiography

Explanation

In a hemodynamically unstable patient with a mechanically unstable pelvic ring injury and a negative FAST, bleeding is predominantly retroperitoneal (venous plexus or arterial). If a pelvic binder does not restore hemodynamic stability, immediate intervention to control hemorrhage is required. This is optimally achieved via Preperitoneal Pelvic Packing, Angioembolization, or REBOA as an adjunct.

Question 6130

Topic: Pelvic & Acetabular Trauma
A 30-year-old male is brought to the trauma bay in hemorrhagic shock following a motorcycle collision. Radiographs demonstrate an anteroposterior compression (APC) type III pelvic ring injury. A circumferential pelvic binder is applied. To achieve the most effective reduction and mechanical stabilization, over which anatomic structure should the binder be centered?
. Anterior superior iliac spines
. Iliac crests
. Greater trochanters
. Pubic symphysis
. Subtrochanteric femur

Correct Answer & Explanation

. Greater trochanters

Explanation

A pelvic binder or sheet must be centered over the greater trochanters to effectively close an open-book pelvic injury. Placement over the iliac crests or ASIS is less effective and can inadvertently cause paradoxical widening of the pelvic inlet or fail to close the posterior ring disruption adequately.

Question 6131

Topic: 2. Trauma
A 28-year-old man sustains a Pauwels type III fracture of the femoral neck. Based on the biomechanics of this fracture pattern, which of the following describes the primary deforming force acting at the fracture site?
. Compression force
. Tension force
. Vertical shear force
. Torsional force
. Distraction force

Correct Answer & Explanation

. Vertical shear force

Explanation

A Pauwels type III femoral neck fracture is characterized by a high fracture angle (typically > 50-70 degrees from the horizontal). Biomechanically, this highly vertical orientation converts the forces of weight-bearing into tremendous vertical shear forces across the fracture site, predisposing the fracture to varus collapse and nonunion.

Question 6132

Topic: 2. Trauma

A 25-year-old male sustains a closed tibial shaft fracture. Twelve hours later, he complains of severe, unrelenting leg pain exacerbated by passive stretch of his toes. Compartment syndrome is suspected, and pressures are measured using a slit catheter. Which of the following pressure criteria (delta pressure) is universally considered the threshold indicating an absolute need for emergency fasciotomy?

. Mean arterial pressure minus compartment pressure < 40 mmHg
. Diastolic blood pressure minus compartment pressure < 30 mmHg
. Systolic blood pressure minus compartment pressure < 30 mmHg
. Absolute compartment pressure > 20 mmHg
. Absolute compartment pressure > 25 mmHg

Correct Answer & Explanation

. Diastolic blood pressure minus compartment pressure < 30 mmHg

Explanation

The diagnosis of acute compartment syndrome is primarily clinical, but when pressure measurements are used, the 'delta pressure' is the most reliable metric. Delta P is calculated as the Diastolic Blood Pressure minus the Compartment Pressure. A delta pressure of < 30 mmHg indicates inadequate tissue perfusion and is the standard threshold for surgical fasciotomy.

Question 6133

Topic: Pelvic & Acetabular Trauma

A 35-year-old male sustains a closed pelvic ring injury. Examination reveals a large, fluctuant swelling over the greater trochanteric region with overlying skin bruising. Aspiration yields serosanguinous fluid. What is the precise anatomic location of this fluid collection in a Morel-Lavallee lesion?

. Between the epidermis and the dermis
. Between the dermis and the subcutaneous fat
. Between the subcutaneous fat and the deep fascia
. Between the deep fascia and the underlying muscle
. Deep to the muscle, adjacent to the periosteum

Correct Answer & Explanation

. Between the subcutaneous fat and the deep fascia

Explanation

A Morel-Lavallee lesion is a post-traumatic closed degloving injury where the subcutaneous tissue is sheared off and separated from the underlying deep (muscular) fascia. This creates a potential space that rapidly fills with blood, lymph, and necrotic fat.

Question 6134

Topic: 2. Trauma

A 30-year-old male presents with a complex intra-articular distal femur fracture. Axial CT imaging demonstrates an isolated coronal plane fracture of the lateral femoral condyle. What is the appropriate eponymous name for this specific fracture pattern?

. Barton's fracture
. Chopart's fracture
. Pilon fracture
. Hoffa fracture
. Tillaux fracture

Correct Answer & Explanation

. Hoffa fracture

Explanation

A Hoffa fracture is a coronal plane fracture of the distal femoral condyle, most commonly involving the lateral condyle. It is intrinsically unstable due to shear forces and typically requires operative fixation with lag screws oriented anterior-to-posterior (or posterior-to-anterior).

Question 6135

Topic: Pelvic & Acetabular Trauma
A 45-year-old male is brought to the trauma bay after an MVA. He is hypotensive (BP 70/40 mmHg) and tachycardic (HR 130 bpm). Primary survey reveals an unstable pelvis (APC III pattern). A pelvic binder is applied, and he receives 2 units of packed RBCs. His BP improves transiently but drops again to 75/45 mmHg. A FAST scan is negative. What is the most appropriate next step in management?
. CT angiogram of the pelvis
. Preperitoneal pelvic packing and/or pelvic angiography
. Exploratory laparotomy
. Application of an anterior external fixator in the ER
. Bilateral internal iliac artery ligation

Correct Answer & Explanation

. Preperitoneal pelvic packing and/or pelvic angiography

Explanation

In a hemodynamically unstable patient with a pelvic ring injury who remains hypotensive despite initial resuscitation and mechanical stabilization (pelvic binder), and who has a negative FAST (ruling out massive intra-abdominal hemorrhage), the next step is addressing pelvic bleeding. This is achieved via preperitoneal pelvic packing or pelvic angiography/embolization, depending on institutional protocols and available resources.

Question 6136

Topic: 2. Trauma

A 24-year-old male presents with persistent wrist pain 8 months after a fall. Imaging reveals a proximal pole scaphoid nonunion. MRI demonstrates avascular necrosis (AVN) of the proximal pole, with the absence of punctate bleeding confirmed intraoperatively. Which of the following is the most appropriate surgical treatment?

. Percutaneous headless compression screw fixation without grafting
. Open reduction with non-vascularized iliac crest bone graft and K-wire fixation
. 1,2 Intercompartmental supraretinacular artery (1,2-ICSRA) vascularized bone graft
. Free vascularized medial femoral condyle bone graft
. Proximal row carpectomy

Correct Answer & Explanation

. Free vascularized medial femoral condyle bone graft

Explanation

For a scaphoid proximal pole nonunion with established AVN (especially with absence of intraoperative punctate bleeding) and fragmentation or structural collapse, a free vascularized bone graft (such as from the medial femoral condyle) provides superior union rates compared to non-vascularized grafts or local pedicled grafts (like 1,2-ICSRA), which have higher failure rates in the setting of severe AVN.

Question 6137

Topic: 2. Trauma

You are treating a 30-year-old male with a lateral Hoffa fracture (coronal shear fracture of the lateral femoral condyle). You plan for open reduction and internal fixation. To achieve the most biomechanically stable construct for interfragmentary compression, what is the optimal trajectory for the screws?

. Anterior to posterior (AP) directed screws
. Posterior to anterior (PA) directed screws
. Medial to lateral directed screws
. Lateral to medial directed screws
. Distal to proximal directed screws

Correct Answer & Explanation

. Posterior to anterior (PA) directed screws

Explanation

Biomechanical studies show that for a lateral Hoffa fracture, screws directed from posterior-to-anterior (PA) provide superior fixation strength, higher load-to-failure, and better compression compared to anterior-to-posterior (AP) screws. This is due to the thicker cortical bone posteriorly and the trajectory being perpendicular to the fracture plane.

Question 6138

Topic: 2. Trauma
A 25-year-old male is admitted with a comminuted midshaft tibia fracture. Overnight, he requires escalating doses of IV opioids. On examination, his leg is tense, and he has severe pain with passive stretch of the extensor hallucis longus. His blood pressure is 110/70 mmHg. Intracompartmental pressure monitoring of the anterior compartment yields a reading of 45 mmHg. What is his Delta P, and what is the appropriate management?
. Delta P is 65 mmHg; continue close observation
. Delta P is 65 mmHg; perform an urgent four-compartment fasciotomy
. Delta P is 25 mmHg; continue close observation
. Delta P is 25 mmHg; perform an urgent four-compartment fasciotomy
. Delta P is 45 mmHg; elevate the leg and apply ice

Correct Answer & Explanation

. Delta P is 25 mmHg; perform an urgent four-compartment fasciotomy

Explanation

Delta P (ΔP) is defined as the Diastolic Blood Pressure minus the Intracompartmental Pressure. In this case, 70 mmHg (Diastolic BP) - 45 mmHg (Compartment Pressure) = 25 mmHg. A Delta P of less than 30 mmHg is an absolute indication for emergent four-compartment fasciotomy to prevent irreversible muscle and nerve necrosis.

Question 6139

Topic: Pelvic & Acetabular Trauma
A 30-year-old male is brought to the trauma bay following a high-speed motor vehicle collision. He has an anteroposterior compression (APC III) pelvic ring injury and is hemodynamically unstable. A pelvic binder is applied, but he remains hypotensive. FAST exam is negative. What is the most common anatomical source of massive hemorrhage in this clinical scenario?
. Superior gluteal artery
. Internal pudendal artery
. Presacral venous plexus
. Obturator artery
. External iliac vein

Correct Answer & Explanation

. Presacral venous plexus

Explanation

In severe pelvic ring disruptions, 80-90% of massive hemorrhage is venous in origin, primarily from the presacral venous plexus and bleeding from the cancellous bone surfaces. Arterial bleeding (e.g., superior gluteal, internal pudendal) accounts for only 10-20% of cases, though it may require specific interventions such as angioembolization if venous bleeding is controlled via pelvic packing/binder.

Question 6140

Topic: Pelvic & Acetabular Trauma
In a Young-Burgess Anterior Posterior Compression Type III (APC III) pelvic ring injury, which of the following ligamentous complexes is definitively disrupted compared to an APC II injury?
. Anterior sacroiliac ligaments
. Sacrospinous ligaments
. Sacrotuberous ligaments
. Posterior sacroiliac ligaments
. Iliolumbar ligaments

Correct Answer & Explanation

. Posterior sacroiliac ligaments

Explanation

APC II involves disruption of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments, while the posterior sacroiliac ligaments remain intact, maintaining some vertical stability. APC III involves complete disruption of both anterior and posterior sacroiliac ligaments, causing complete multidirectional pelvic instability.

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