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2. Trauma MCQs

Practice Set 294 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 5861

Topic: 2. Trauma
A 32-year-old male sustains a severe closed tibial shaft fracture. Two hours later in the emergency department, he complains of severe leg pain out of proportion to the injury, unrelieved by intravenous opioids. His blood pressure is 110/70 mmHg. Intracompartmental pressure monitoring of the anterior compartment yields a value of 45 mmHg. Which of the following calculations is the most reliable indicator for emergency fasciotomy?
. Absolute compartment pressure > 30 mmHg regardless of blood pressure
. Delta pressure (Mean Arterial Pressure - Compartment Pressure) < 30 mmHg
. Delta pressure (Diastolic Blood Pressure - Compartment Pressure) < 30 mmHg
. Delta pressure (Systolic Blood Pressure - Compartment Pressure) < 30 mmHg
. The ratio of Compartment Pressure to Diastolic Blood Pressure > 0.5

Correct Answer & Explanation

. Delta pressure (Diastolic Blood Pressure - Compartment Pressure) < 30 mmHg

Explanation

The most reliable objective criteria for diagnosing acute compartment syndrome is a delta pressure (ΔP) of less than 30 mmHg. Delta pressure is defined as the Diastolic Blood Pressure minus the Compartment Pressure (ΔP = DBP - CP). In this scenario, DBP is 70 and CP is 45. ΔP = 70 - 45 = 25 mmHg. Since this is less than 30 mmHg, emergent four-compartment fasciotomy is indicated. Absolute pressure thresholds (e.g., > 30 mmHg) are less accurate as they do not account for patient perfusion pressure, which fluctuates.

Question 5862

Topic: 2. Trauma

A 40-year-old patient sustained a high radial nerve palsy following a humerus shaft fracture 12 months ago with no clinical or EMG signs of recovery. Which of the following tendon transfer combinations represents the classic modified Green transfer to restore wrist, finger, and thumb extension?

. Pronator teres to extensor carpi radialis brevis; flexor carpi radialis to extensor digitorum communis; palmaris longus to extensor pollicis longus
. Pronator teres to extensor carpi radialis longus; flexor carpi radialis to extensor digitorum communis; flexor digitorum superficialis to extensor pollicis longus
. Pronator teres to extensor carpi radialis brevis; flexor carpi ulnaris to extensor digitorum communis; palmaris longus to extensor pollicis longus
. Brachioradialis to extensor carpi radialis brevis; flexor carpi ulnaris to extensor digitorum communis; flexor carpi radialis to extensor pollicis longus
. Pronator teres to extensor carpi ulnaris; flexor digitorum superficialis to extensor digitorum communis; palmaris longus to extensor pollicis longus

Correct Answer & Explanation

. Pronator teres to extensor carpi radialis brevis; flexor carpi ulnaris to extensor digitorum communis; palmaris longus to extensor pollicis longus

Explanation

The classic modified Green transfer for radial nerve palsy uses the Pronator Teres (PT) to Extensor Carpi Radialis Brevis (ECRB) for wrist extension, the Flexor Carpi Ulnaris (FCU) to the Extensor Digitorum Communis (EDC) for finger extension, and the Palmaris Longus (PL) to the Extensor Pollicis Longus (EPL) for thumb extension. (The Boyes transfer traditionally utilizes the FDS rather than the FCU for finger extension).

Question 5863

Topic: 2. Trauma
A 30-year-old man sustains a Pauwels type III (70-degree) femoral neck fracture. Biomechanically, what is the primary deforming force at the fracture site that surgical fixation must overcome, and what is the preferred characteristic of the construct to achieve optimal stability?
. Compressive forces; screws placed perpendicular to the femoral shaft
. Shear forces; construct designed to neutralize shear (e.g., length-stable device or screws placed perpendicular to the fracture line)
. Tensile forces; tension band wiring combined with cancellous screws
. Rotational forces; a single large diameter dynamic hip screw
. Distraction forces; an intramedullary nail with dynamic interlocking

Correct Answer & Explanation

. Shear forces; construct designed to neutralize shear (e.g., length-stable device or screws placed perpendicular to the fracture line)

Explanation

A Pauwels type III fracture is characterized by a vertical fracture line (angle > 50 degrees). Biomechanically, this creates extraordinarily high shear forces at the fracture site, which promote varus displacement and nonunion. Standard sliding hip screws without derotation components may allow excessive sliding and collapse. Fixation must primarily neutralize these shear forces, often through length-stable constructs (like a fixed-angle blade plate or proximal femoral locking plate) or multiple screws placed to cross the vertical fracture orthogonally.

Question 5864

Topic: 2. Trauma

A 75-year-old male presents with neck pain after a low-energy ground-level fall. CT scan reveals a Type II odontoid fracture. Which of the following factors is most strongly associated with an increased risk of nonunion if this fracture is treated non-operatively with rigid cervical orthosis?

. Fracture displacement of 2 mm
. Anterior angulation of 5 degrees
. Patient age > 65 years
. Delay in treatment of 3 days
. Associated isolated posterior arch fracture of C1

Correct Answer & Explanation

. Patient age > 65 years

Explanation

Risk factors for nonunion of Type II odontoid fractures include patient age > 50-65 years, fracture displacement > 5 mm, posterior displacement, and a delay in diagnosis/treatment of > 1 week. Among the options provided, age > 65 is an established strong independent risk factor for nonunion, often prompting consideration for early surgical stabilization in suitable candidates.

Question 5865

Topic: 2. Trauma
A 28-year-old male is brought to the emergency department after a high-speed motorcycle collision. Pelvic radiographs reveal an anteroposterior compression (APC) type III pelvic ring injury. Clinically, he has blood at the urethral meatus and a high-riding prostate on digital rectal examination. Which of the following is the most appropriate next step in the management of his suspected urologic injury?
. Placement of a Foley catheter by an experienced urologist
. Immediate suprapubic catheter placement
. Retrograde urethrogram
. Computed tomography (CT) cystogram
. Diagnostic laparoscopy

Correct Answer & Explanation

. Retrograde urethrogram

Explanation

Blood at the urethral meatus, a high-riding prostate, and perineal bruising are classic signs of a posterior urethral injury, which is highly associated with pelvic fractures (especially those involving disruption of the pubic symphysis). A retrograde urethrogram (RUG) is the gold standard diagnostic test to evaluate the integrity of the urethra. Blind insertion of a Foley catheter is contraindicated as it may convert a partial urethral tear into a complete tear. A CT cystogram is useful for diagnosing bladder ruptures but should be performed only after the urethra has been cleared.

Question 5866

Topic: 2. Trauma

A 40-year-old pedestrian is struck by a vehicle and sustains a high-energy fracture of the knee. Radiographs reveal a depressed, displaced fracture of the medial tibial plateau with an associated intercondylar eminence extension. According to the Schatzker classification, this is a Type IV fracture. Which of the following statements correctly describes the primary mechanism of injury and the most critical associated neurovascular risk?

. Valgus force with axial loading; common peroneal nerve injury
. Valgus force with axial loading; popliteal artery injury
. Varus force with axial loading; common peroneal nerve injury
. Varus force with axial loading; popliteal artery injury
. Hyperextension force; saphenous nerve injury

Correct Answer & Explanation

. Varus force with axial loading; popliteal artery injury

Explanation

A Schatzker IV fracture involves the medial tibial plateau. The medial plateau is structurally denser and stronger than the lateral plateau, meaning fractures here require significantly higher energy, typically a varus force combined with axial loading. Because of this high-energy mechanism and the close anatomical proximity of the popliteal artery to the posterior aspect of the knee (tethered at the adductor hiatus and soleal arch), these fractures carry a notoriously high risk of popliteal artery injury and knee dislocation equivalents.

Question 5867

Topic: Pelvic & Acetabular Trauma

In the Young-Burgess classification, an Anteroposterior Compression (APC) Type II pelvic ring injury is characterized by pubic symphysis diastasis and disruption of which of the following posterior ring structures?

. Anterior sacroiliac ligaments with intact posterior sacroiliac ligaments
. Posterior sacroiliac ligaments with intact anterior sacroiliac ligaments
. Complete disruption of both anterior and posterior sacroiliac ligaments
. Fracture of the sacral ala with intact sacroiliac ligaments
. Disruption of the iliolumbar ligament only

Correct Answer & Explanation

. Anterior sacroiliac ligaments with intact posterior sacroiliac ligaments

Explanation

An APC II injury involves widening of the pubic symphysis and rupture of the anterior sacroiliac ligaments, sacrospinous, and sacrotuberous ligaments. The strong posterior sacroiliac ligaments remain intact, which prevents vertical displacement but allows the hemipelvis to "open like a book," resulting in rotational instability.

Question 5868

Topic: 2. Trauma
A 32-year-old male sustains a closed tibia fracture and develops worsening leg pain out of proportion to the injury. Suspecting acute compartment syndrome, the surgeon decides to measure tissue pressure. The modern threshold for performing a fasciotomy is defined by calculating the "delta P" (ΔP). Which of the following correctly defines the ΔP threshold used as an absolute indication for fasciotomy?
. Diastolic blood pressure minus compartment pressure ≤ 30 mmHg
. Systolic blood pressure minus compartment pressure ≤ 30 mmHg
. Mean arterial pressure minus compartment pressure ≤ 30 mmHg
. Compartment pressure > 20 mmHg regardless of systemic blood pressure
. Compartment pressure > 30 mmHg regardless of systemic blood pressure

Correct Answer & Explanation

. Diastolic blood pressure minus compartment pressure ≤ 30 mmHg

Explanation

The Delta P (ΔP) is calculated as the Diastolic Blood Pressure minus the intracompartmental pressure. A ΔP of 30 mmHg or less (e.g., Diastolic BP is 70 and compartment pressure is 45; 70-45 = 25) indicates inadequate tissue perfusion and is a strong indication for urgent four-compartment fasciotomy. Absolute pressure thresholds are less reliable because perfusion pressure is dependent on systemic blood pressure.

Question 5869

Topic: 2. Trauma
A 45-year-old male is brought to the trauma bay after a crush injury. Radiographs reveal an Anterior-Posterior Compression type III (APC-III) pelvic ring injury. If the patient develops life-threatening arterial hemorrhage, which of the following vessels is most commonly the source and targeted for embolization?
. Superior gluteal artery
. Internal pudendal artery
. External iliac artery
. Inferior mesenteric artery
. Common femoral artery

Correct Answer & Explanation

. Internal pudendal artery

Explanation

Arterial bleeding in APC pelvic fractures is typically from the anterior division of the internal iliac artery, most commonly the internal pudendal or obturator arteries. In contrast, Lateral Compression (LC) injuries more commonly compromise the superior gluteal artery, which is a branch of the posterior division.

Question 5870

Topic: 2. Trauma

A 28-year-old male cyclist sustains a middle-third clavicle fracture after a fall. Radiographs show significant displacement with the medial fragment pulled superiorly and posteriorly. Which muscle is primarily responsible for the displacement of the medial fragment?

. Pectoralis major
. Sternocleidomastoid
. Trapezius
. Deltoid
. Subclavius

Correct Answer & Explanation

. Sternocleidomastoid

Explanation

In fractures of the midshaft clavicle, the medial fragment is typically displaced posterosuperiorly by the unopposed pull of the sternocleidomastoid muscle. The distal fragment is displaced inferiorly and medially by the weight of the arm and the pull of the pectoralis major and latissimus dorsi.

Question 5871

Topic: 2. Trauma

A 35-year-old male undergoes intramedullary nailing for a severely comminuted diaphyseal tibia fracture. Twelve hours post-operatively, he complains of intractable leg pain exacerbated by passive toe flexion. If compartment syndrome is developing, which compartment is historically the most susceptible and contains the deep peroneal nerve?

. Superficial posterior compartment
. Deep posterior compartment
. Anterior compartment
. Lateral compartment
. Peroneal compartment

Correct Answer & Explanation

. Anterior compartment

Explanation

The anterior compartment of the leg is the most commonly affected compartment in acute compartment syndrome following tibia fractures. It contains the tibialis anterior, extensor hallucis longus, extensor digitorum longus, peroneus tertius, the anterior tibial artery, and the deep peroneal nerve.

Question 5872

Topic: Pelvic & Acetabular Trauma
According to the Young and Burgess classification, which of the following pelvic ring injuries is most highly associated with massive retroperitoneal hemorrhage requiring angioembolization?
. Anterior posterior compression (APC) type I
. Anterior posterior compression (APC) type III
. Lateral compression (LC) type I
. Lateral compression (LC) type II
. Vertical shear (VS)

Correct Answer & Explanation

. Anterior posterior compression (APC) type III

Explanation

APC III pelvic ring injuries involve complete disruption of the anterior and posterior pelvic rings (symphysis, sacrospinous, sacrotuberous, and anterior/posterior sacroiliac ligaments). This massive volume expansion and disruption of the posterior venous plexus and arterial branches carry the highest risk for massive retroperitoneal hemorrhage.

Question 5873

Topic: Lower Extremity Trauma

A 45-year-old male sustains a Schatzker Type VI tibial plateau fracture. During surgical approach, the surgeon utilizes a dual-incision technique (anterolateral and posteromedial). Which structure is at greatest risk of iatrogenic injury during the superficial dissection of the posteromedial approach?

. Common peroneal nerve
. Anterior tibial artery
. Saphenous nerve
. Medial superior genicular artery
. Popliteal artery

Correct Answer & Explanation

. Saphenous nerve

Explanation

The posteromedial approach to the tibial plateau requires careful dissection through the superficial tissues, where the saphenous nerve and great saphenous vein reside and are at highest risk of iatrogenic injury. Deep dissection retracts the pes anserinus tendons and protects the MCL.

Question 5874

Topic: 2. Trauma
The Superior Shoulder Suspensory Complex (SSSC) is a bone-and-soft-tissue ring attached to the axial skeleton. Which of the following combinations of injuries constitutes a 'double disruption' of the SSSC, often necessitating surgical intervention to prevent a drooping shoulder?
. Midshaft clavicle fracture and acromioclavicular (AC) joint separation
. Fracture of the coracoid process and fracture of the glenoid neck
. Fracture of the distal third of the clavicle and rupture of the coracoclavicular (CC) ligaments
. Fracture of the scapular spine and tear of the supraspinatus tendon
. Fracture of the glenoid articular surface and Bankart lesion

Correct Answer & Explanation

. Fracture of the distal third of the clavicle and rupture of the coracoclavicular (CC) ligaments

Explanation

The SSSC consists of the glenoid, coracoid, CC ligaments, distal clavicle, AC joint, and acromion. A double disruption occurs when there are two breaks in this functional ring, severely destabilizing the shoulder girdle. A classic double disruption is a fracture of the distal clavicle combined with disruption of the CC ligaments (or coracoid fracture).

Question 5875

Topic: Lower Extremity Trauma

A 35-year-old male sustains a severe Schatzker IV tibial plateau fracture with a large, displaced posteromedial fragment. The surgeon elects to perform a direct posteromedial approach for optimal buttress plating. This surgical approach utilizes an internervous/intermuscular interval primarily between which two structures?

. Between the medial gastrocnemius and semimembranosus
. Between the pes anserinus and the medial head of the gastrocnemius
. Between the soleus and the popliteus
. Between the medial collateral ligament and the posterior oblique ligament
. Between the flexor hallucis longus and the Achilles tendon

Correct Answer & Explanation

. Between the pes anserinus and the medial head of the gastrocnemius

Explanation

The standard posteromedial approach to the tibial plateau utilizes the interval between the pes anserinus tendons anteriorly and the medial head of the gastrocnemius posteriorly. Retracting the pes anteriorly and the gastrocnemius (and soleus) posteriorly exposes the posteromedial metaphysis of the proximal tibia safely.

Question 5876

Topic: 2. Trauma

A 65-year-old woman sustains a nondisplaced fracture of the distal radius. She is treated nonoperatively in a well-molded short-arm cast. Six weeks later, immediately after cast removal, she is unable to actively extend her thumb interphalangeal joint. What is the most widely accepted primary etiology for this delayed extensor pollicis longus (EPL) tendon rupture in the setting of a nondisplaced fracture?

. Primary mechanical attrition against a prominent dorsal metaphyseal spike
. Ischemia due to increased compartment pressure and hematoma within the intact third dorsal compartment
. Iatrogenic laceration during cast application or removal
. Missed complete traumatic rupture at the time of the initial injury
. Synovial inflammation secondary to localized external cast pressure over the Lister tubercle

Correct Answer & Explanation

. Ischemia due to increased compartment pressure and hematoma within the intact third dorsal compartment

Explanation

EPL ruptures occurring after non-displaced distal radius fractures are primarily ischemic in etiology. The intact extensor retinaculum creates a closed space (the third dorsal compartment). The fracture hematoma increases pressure, compromising the tenuous blood supply of the EPL tendon, leading to delayed avascular necrosis and rupture. Displaced fractures typically cause mechanical attrition.

Question 5877

Topic: 2. Trauma

A 35-year-old male sustains a high-energy coronal plane fracture of the lateral femoral condyle (Hoffa fracture). What is the biomechanically optimal screw fixation construct for this specific fracture pattern?

. Two anteroposterior (AP) partially threaded lag screws
. Two posteroanterior (PA) partially threaded lag screws
. A single large-fragment anteroposterior (AP) lag screw
. Lateral locked plating without independent lag screws
. Medial locked plating with independent lag screws

Correct Answer & Explanation

. Two posteroanterior (PA) partially threaded lag screws

Explanation

Hoffa fractures are coronal shear fractures of the femoral condyle. Biomechanical studies have demonstrated that posteroanterior (PA) lag screw placement is biomechanically superior to anteroposterior (AP) screw placement because PA screws are inserted perpendicular to the fracture plane and engage the denser subchondral bone of the anterior metaphysis. Two screws are used to prevent rotation.

Question 5878

Topic: Pelvic & Acetabular Trauma
A 28-year-old hypotensive male is brought to the trauma bay following a motorcycle crash. An AP pelvis radiograph demonstrates an 'open book' (APC-III) pelvic ring injury. A pelvic binder is ordered. At what specific anatomic landmark should the binder be centered to optimally reduce the pelvic volume?
. Anterior superior iliac spines (ASIS)
. Iliac crests
. Greater trochanters
. Ischial tuberosities
. Pubic symphysis

Correct Answer & Explanation

. Greater trochanters

Explanation

To effectively reduce the pelvic volume and close a pubic diastasis in an unstable pelvic ring injury, the pelvic binder or sheet must be centered directly over the greater trochanters. Placing it higher (e.g., over the iliac crests or ASIS) is a common clinical error that can inadvertently gap the symphysis further or fail to provide adequate mechanical reduction.

Question 5879

Topic: 2. Trauma

A 32-year-old cyclist sustains an acute, closed, midshaft clavicle fracture after a fall. Which of the following clinical or radiographic findings is considered an absolute indication for open reduction and internal fixation?

. Shortening of 1.5 cm
. 100% displacement without skin tenting
. Presence of a Z-fragment
. Skin tenting with impending soft tissue necrosis
. Severe comminution

Correct Answer & Explanation

. Skin tenting with impending soft tissue necrosis

Explanation

Absolute indications for operative fixation of a clavicle fracture include open fractures, fractures causing skin tenting with impending soft tissue necrosis, associated neurovascular injury, and a widely displaced 'floating shoulder.' While 100% displacement, comminution, and significant shortening (>2 cm) are strong relative indications, skin tenting with impending necrosis requires urgent operative intervention.

Question 5880

Topic: Pelvic & Acetabular Trauma
In the acute management of a hemodynamically unstable patient with an anteroposterior compression (APC) type III pelvic ring injury, what is the correct anatomical landmark for the placement of a circumferential pelvic sheet or binder?
. Over the iliac crests
. At the level of the anterior superior iliac spines
. Centered over the greater trochanters
. Over the umbilicus
. Distal to the lesser trochanters

Correct Answer & Explanation

. Centered over the greater trochanters

Explanation

A pelvic binder must be centered over the greater trochanters and the symphysis pubis to provide maximal compressive force to close the pelvic volume. Placing it too high (e.g., over the iliac crests or ASIS) is less effective and may paradoxically open the pelvis further, in addition to restricting abdominal access.

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