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2. Trauma MCQs

Practice Set 295 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 5881

Topic: 2. Trauma

In a coronal shear fracture of the lateral femoral condyle (Hoffa fracture), which of the following structures remains attached to the osteochondral fragment and predominantly contributes to its posterior and distal displacement?

. Anterior cruciate ligament
. Popliteus tendon
. Medial collateral ligament
. Posterior cruciate ligament
. Adductor magnus tendon

Correct Answer & Explanation

. Popliteus tendon

Explanation

A Hoffa fracture most commonly involves the lateral femoral condyle. The lateral fragment is subjected to displacing forces from the soft tissue attachments, specifically the lateral collateral ligament, the lateral head of the gastrocnemius, and the popliteus tendon, which pull the fragment posteriorly and distally.

Question 5882

Topic: 2. Trauma

A 25-year-old male sustains a high-energy knee dislocation. It is closed-reduced in the emergency department. Post-reduction, his pulses are symmetric and bounding. The Ankle-Brachial Index (ABI) is measured at 0.85. What is the most appropriate next step in management?

. Discharge with knee immobilizer and close clinical follow-up
. Observation with serial ABIs every 2 hours
. Computed Tomography (CT) Angiography
. Immediate vascular surgery consultation for exploration
. Emergent prophylactic four-compartment fasciotomy

Correct Answer & Explanation

. Computed Tomography (CT) Angiography

Explanation

In knee dislocations, vascular assessment is critical due to the high risk of popliteal artery injury. Even in the presence of palpable symmetric pulses, an ABI less than 0.9 is a strong indicator of a potential vascular injury and warrants an immediate CT angiogram. An ABI greater than 0.9 allows for observation with serial exams.

Question 5883

Topic: Pelvic & Acetabular Trauma

A 34-year-old male is involved in a motorcycle collision and sustains an Anteroposterior Compression Type II (APC-II) pelvic ring injury. Based on the Young-Burgess classification, which of the following ligamentous structures is entirely disrupted in an APC-II injury but intact in an APC-I injury?

. Symphysis pubis only
. Anterior sacroiliac, sacrotuberous, and sacrospinous ligaments
. Posterior sacroiliac ligaments
. Iliolumbar ligaments
. Sacrotuberous ligaments only

Correct Answer & Explanation

. Anterior sacroiliac, sacrotuberous, and sacrospinous ligaments

Explanation

In the Young-Burgess classification, an APC-I injury involves disruption of the symphysis pubis (less than 2.5 cm diastasis) but intact anterior and posterior pelvic ligaments. An APC-II injury is characterized by a symphysis diastasis >2.5 cm and disruption of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments. The posterior sacroiliac ligaments remain intact in APC-II, providing vertical stability but leaving rotational instability.

Question 5884

Topic: 2. Trauma

A 32-year-old man sustains a severe closed diaphyseal tibia fracture. Six hours later, he develops excruciating leg pain that is unresponsive to IV narcotics. The most prominent clinical sign is severe pain upon passive stretching of the extensor hallucis longus. To definitively diagnose acute compartment syndrome, compartment pressure measurements are obtained. Which of the following pressure profiles is the accepted threshold for performing an emergency fasciotomy?

. Delta P (Diastolic Blood Pressure minus Compartment Pressure) < 30 mmHg
. Delta P (Systolic Blood Pressure minus Compartment Pressure) < 30 mmHg
. Absolute Compartment Pressure > 20 mmHg
. Delta P (Mean Arterial Pressure minus Compartment Pressure) < 40 mmHg
. Delta P (Diastolic Blood Pressure minus Compartment Pressure) > 45 mmHg

Correct Answer & Explanation

. Delta P (Diastolic Blood Pressure minus Compartment Pressure) < 30 mmHg

Explanation

Acute compartment syndrome is a clinical diagnosis, with pain out of proportion and pain with passive stretch being early signs. When utilizing pressure measurements, the delta pressure (Delta P) concept is most reliable. Delta P is calculated as Diastolic Blood Pressure minus Compartment Pressure. A Delta P of less than 30 mmHg (meaning the compartment pressure is approaching the diastolic pressure) indicates inadequate tissue perfusion and is the accepted threshold for fasciotomy.

Question 5885

Topic: 2. Trauma

When applying a locking plate to a comminuted diaphyseal fracture using bridge plating techniques, secondary bone healing (callus formation) is desired. To promote this healing, the construct requires a certain degree of flexibility. Which of the following technical modifications will best increase the 'working length' of the plate to achieve appropriate interfragmentary motion?

. Using bicortical locking screws instead of unicortical locking screws
. Increasing the distance between the fracture site and the innermost screws
. Placing screws in every available plate hole directly over the comminution
. Using a shorter plate to minimize the span
. Compressing the plate tightly to the bone using standard non-locking screws first

Correct Answer & Explanation

. Increasing the distance between the fracture site and the innermost screws

Explanation

In bridge plating for comminuted fractures, relative stability is required to stimulate secondary bone healing (callus). The 'working length' of the plate is defined as the distance between the closest screws on either side of the fracture. Increasing this distance makes the construct more flexible, allowing micro-motion that stimulates callus formation. Filling all holes or placing screws very close to the fracture makes the construct overly rigid, which can suppress callus formation and lead to nonunion.

Question 5886

Topic: 2. Trauma
A 45-year-old pedestrian is struck by a car and sustains a knee injury. Radiographs show a fracture of the medial tibial plateau with depression and extension into the metadiaphysis. According to the Schatzker classification, what type of fracture is this?
. Type II
. Type III
. Type IV
. Type V
. Type VI

Correct Answer & Explanation

. Type IV

Explanation

Schatzker classification: I = Lateral split; II = Lateral split-depression; III = Lateral pure depression; IV = Medial plateau fracture (split or depression); V = Bicondylar plateau fracture; VI = Plateau fracture with meta-diaphyseal dissociation. A medial plateau fracture is Type IV, which typically results from a varus force and often involves higher energy.

Question 5887

Topic: 2. Trauma

The primary blood supply to the proximal pole of the scaphoid enters the bone at which anatomical location?

. Volar tubercle
. Dorsal ridge
. Proximal articular surface
. Distal articular surface
. Scapholunate ligament insertion

Correct Answer & Explanation

. Dorsal ridge

Explanation

The primary blood supply to the scaphoid is derived from the radial artery. The major vessels (providing 70-80% of the blood supply, including the entire proximal pole) enter the scaphoid via the dorsal ridge in a retrograde fashion. A smaller volar branch enters at the distal tubercle. This retrograde supply puts proximal pole fractures at high risk for AVN.

Question 5888

Topic: 2. Trauma

A 35-year-old male sustains an isolated closed scapular body fracture following a motor vehicle collision. According to current evidence-based guidelines, which of the following radiographic parameters is an accepted indication for operative fixation of the scapular body?

. Glenopolar angle of 35 degrees
. Medial/lateral displacement of 10 mm
. Medial/lateral displacement of 25 mm combined with 30 degrees of angular deformity
. Intra-articular step-off of 2 mm at the glenoid
. Coracoid process fracture with 5 mm of displacement

Correct Answer & Explanation

. Medial/lateral displacement of 25 mm combined with 30 degrees of angular deformity

Explanation

Operative indications for scapular body and neck fractures include medial/lateral displacement > 20 mm, angular deformity > 45 degrees, or a combination of displacement > 15 mm and angulation > 30 degrees. A glenopolar angle < 22 degrees is also an indication for surgery. Normal glenopolar angle is 30-45 degrees. Glenoid fractures typically require > 4 mm of step-off to indicate fixation.

Question 5889

Topic: Pelvic & Acetabular Trauma
A 35-year-old male sustains an anteroposterior compression type III (APC-III) pelvic ring injury. He is hemodynamically unstable despite initial resuscitation and the application of a pelvic binder. A FAST scan is negative. What is the most appropriate next step in management?
. Immediate exploratory laparotomy
. Preperitoneal pelvic packing and/or angiography
. Skeletal traction of the lower extremities
. Open reduction and internal fixation of the symphysis pubis
. Sacroiliac screw fixation

Correct Answer & Explanation

. Preperitoneal pelvic packing and/or angiography

Explanation

In a patient with a mechanically unstable pelvic ring injury and persistent hemodynamic instability despite a pelvic binder, if intraperitoneal bleeding has been ruled out (negative FAST), the source of bleeding is assumed to be the pelvic retroperitoneum. The standard algorithm involves either emergent preperitoneal pelvic packing (PPP) or pelvic angiography with embolization to address venous or arterial hemorrhage, respectively.

Question 5890

Topic: 2. Trauma

When performing a posteromedial approach to the tibia for open reduction and internal fixation of a Schatzker IV tibial plateau fracture, the surgical interval is developed between which two structures?

. Semimembranosus and medial head of the gastrocnemius
. Pes anserinus and medial head of the gastrocnemius
. Tibialis posterior and flexor digitorum longus
. Soleus and lateral head of the gastrocnemius
. Popliteus and soleus

Correct Answer & Explanation

. Pes anserinus and medial head of the gastrocnemius

Explanation

The posteromedial approach to the proximal tibia utilizes the internervous/intermuscular interval between the medial head of the gastrocnemius (which is retracted posteriorly and laterally, protecting the neurovascular bundle) and the pes anserinus tendons (which are retracted anteriorly). This allows direct access to the posteromedial articular fragment commonly seen in Schatzker IV, V, and VI fractures.

Question 5891

Topic: 2. Trauma

In the Young-Burgess classification of pelvic ring injuries, a Lateral Compression Type II (LC-2) fracture pattern is classically defined by which of the following posterior ring injuries?

. Complete disruption of the posterior sacroiliac ligaments with SI joint dislocation
. A comminuted sacral fracture with horizontal extension
. An iliac wing fracture with an intact posterior sacroiliac ligament complex (crescent fracture)
. A vertically unstable sacral ala fracture
. Bilateral sacral fractures with a transverse component (U-type)

Correct Answer & Explanation

. An iliac wing fracture with an intact posterior sacroiliac ligament complex (crescent fracture)

Explanation

In the Young-Burgess classification, an LC-2 injury involves a lateral compression force that results in an anterior ring injury (e.g., rami fractures) and a posterior injury characterized by an iliac wing fracture that extends into the sacroiliac joint. The dense posterior sacroiliac ligaments remain intact, holding the posterior iliac fragment to the sacrum, while the anterior portion of the iliac wing hinges inward. This is commonly referred to as a 'crescent fracture'.

Question 5892

Topic: 2. Trauma

A 30-year-old male sustains a comminuted tibia fracture. He develops severe pain out of proportion to the injury. Which of the following objective compartment pressure measurements is the most accepted indication for performing a four-compartment fasciotomy?

. An absolute compartment pressure greater than 15 mmHg
. A delta pressure (Diastolic Blood Pressure minus Compartment Pressure) less than or equal to 30 mmHg
. A delta pressure (Mean Arterial Pressure minus Compartment Pressure) greater than 40 mmHg
. An absolute compartment pressure equal to the systolic blood pressure
. A delta pressure (Systolic Blood Pressure minus Compartment Pressure) less than 20 mmHg

Correct Answer & Explanation

. A delta pressure (Diastolic Blood Pressure minus Compartment Pressure) less than or equal to 30 mmHg

Explanation

The diagnosis of acute compartment syndrome relies on the concept of 'delta pressure' (the difference between the diastolic blood pressure and the intracompartmental pressure). A delta pressure of 30 mmHg or less (i.e., compartment pressure comes within 30 mmHg of the diastolic BP) indicates inadequate capillary perfusion and is an absolute indication for emergency fasciotomy. Absolute pressures can be misleading, especially in hypotensive patients.

Question 5893

Topic: 2. Trauma
The concept of a 'floating shoulder' historically involves a double disruption of the Superior Suspensory Shoulder Complex (SSSC). Which of the following injury combinations constitutes a classic double disruption of the SSSC?
. Clavicle shaft fracture and coracoid process fracture
. Acromioclavicular joint separation and sternoclavicular joint separation
. Scapular body fracture and proximal humerus fracture
. Clavicle shaft fracture and ipsilateral scapular neck fracture
. Coracoclavicular ligament rupture and acromioclavicular ligament rupture

Correct Answer & Explanation

. Clavicle shaft fracture and ipsilateral scapular neck fracture

Explanation

The Superior Suspensory Shoulder Complex (SSSC) is a ring composed of the glenoid, coracoid, CC ligaments, distal clavicle, AC joint, and acromion. A classic 'floating shoulder' represents a double disruption of this complex, most commonly a fracture of the clavicle shaft combined with an ipsilateral fracture of the scapular neck.

Question 5894

Topic: 2. Trauma
In a 30-year-old patient with a displaced, vertically oriented femoral neck fracture (Pauwels type III, shear angle >50 degrees), what is the most biomechanically stable construct for internal fixation?
. Three parallel cannulated cancellous screws
. A dynamic hip screw (DHS) alone
. A dynamic hip screw (DHS) combined with an anti-rotation screw
. A long cephalomedullary nail
. Two fully threaded cortical screws

Correct Answer & Explanation

. A dynamic hip screw (DHS) combined with an anti-rotation screw

Explanation

Pauwels Type III femoral neck fractures have a high shear angle (vertical fracture line), which makes them highly unstable and prone to varus collapse and nonunion if fixed with standard parallel cannulated screws. Biomechanical studies have shown that a fixed-angle device, such as a Dynamic Hip Screw (DHS), supplemented with an anti-rotation (derotational) screw, provides superior biomechanical stability against shear forces in young adults.

Question 5895

Topic: 2. Trauma

A 22-year-old male sustains a severe closed tibial shaft fracture and rapidly develops tense swelling over the anterolateral leg with excruciating pain on passive toe flexion. If this anterior compartment syndrome is left untreated, which specific sensory deficit is most expected to manifest?

. Loss of sensation over the plantar surface of the foot
. Loss of sensation over the medial malleolus
. Loss of sensation in the first dorsal web space
. Loss of sensation over the lateral dorsum of the foot
. Loss of sensation over the posterior heel

Correct Answer & Explanation

. Loss of sensation in the first dorsal web space

Explanation

The anterior compartment of the leg contains the tibialis anterior, extensor hallucis longus, extensor digitorum longus, peroneus tertius, the anterior tibial artery, and the deep peroneal nerve. Ischemia to the deep peroneal nerve from anterior compartment syndrome classically results in a sensory deficit in its autonomous zone, which is the first dorsal web space of the foot.

Question 5896

Topic: 2. Trauma
A 45-year-old male sustains a knee injury after a fall from a height. Radiographs reveal a fracture of the medial tibial plateau with associated depression and a separate fracture line extending into the intercondylar eminence. According to the Schatzker classification, which type of fracture is this?
. Type II
. Type III
. Type IV
. Type V
. Type VI

Correct Answer & Explanation

. Type IV

Explanation

A fracture of the medial tibial plateau is classified as a Schatzker Type IV. These fractures are typically higher energy than types I-III (which involve the lateral plateau) and are often associated with knee dislocation or subluxation, meniscal tears, and neurovascular injuries. They occur secondary to varus and axial loading forces.

Question 5897

Topic: 2. Trauma

Recombinant human bone morphogenetic protein-2 (rhBMP-2) is utilized in orthopaedic surgery for its potent osteoinductive properties. For which of the following scenarios is rhBMP-2 specifically FDA-approved?

. Posterolateral lumbar fusion
. Cervical spine anterior interbody fusion
. Acute open tibial shaft fractures stabilized with an intramedullary nail
. Nonunion of the scaphoid
. Distal radius fractures in osteoporotic patients

Correct Answer & Explanation

. Acute open tibial shaft fractures stabilized with an intramedullary nail

Explanation

The FDA-approved indications for rhBMP-2 (Infuse) are highly specific: anterior lumbar interbody fusion (ALIF) using an LT-Cage, acute open tibial shaft fractures stabilized with an IM nail (within 14 days of injury), and certain maxillofacial/dental alveolar procedures. Anterior cervical fusion has a black-box warning due to potentially fatal soft tissue swelling.

Question 5898

Topic: 2. Trauma

A 35-year-old male sustains a severe bicondylar tibial plateau fracture. CT imaging reveals a large, displaced posteromedial coronal split fragment. Through which surgical interval is this specific fragment most safely and directly accessed for buttress plate fixation?

. Between the tibialis anterior and extensor hallucis longus
. Between the popliteus and the posterior tibial artery
. Between the medial head of the gastrocnemius and the pes anserinus tendons
. Between the iliotibial band and the biceps femoris
. Between the lateral head of the gastrocnemius and the soleus

Correct Answer & Explanation

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

Explanation

The posteromedial approach to the proximal tibia is performed by developing the internervous/intermuscular interval between the medial head of the gastrocnemius (retracted posteriorly/laterally) and the pes anserinus tendons (semitendinosus, gracilis, sartorius - retracted anteriorly/medially). This provides excellent exposure of the posteromedial tibial plateau.

Question 5899

Topic: 2. Trauma

A 75-year-old male presents with neck pain after a ground-level fall. CT scan demonstrates a Type II odontoid fracture. Which of the following factors most significantly increases his risk of fracture nonunion if he is treated non-operatively with a rigid cervical collar?

. Anterior displacement of 2 mm
. Posterior displacement of 3 mm
. Initial displacement greater than 5 mm
. Angulation of 5 degrees
. Concomitant fracture of the posterior arch of C1

Correct Answer & Explanation

. Initial displacement greater than 5 mm

Explanation

Risk factors for nonunion in Type II odontoid fractures include initial displacement > 5 mm, angulation > 10 degrees, advanced age (typically > 65 years), and delayed diagnosis. Initial displacement greater than 5 mm significantly reduces the chance of healing with external immobilization, often warranting surgical intervention (such as posterior C1-C2 fusion) if the patient can tolerate surgery.

Question 5900

Topic: 2. Trauma
A 45-year-old female sustains a coronal shear fracture of the distal humerus. Intraoperatively, the fracture is identified as a single contiguous osteochondral fragment that involves the entirety of the capitellum and the lateral half of the trochlea. Under the expanded Bryan and Morrey classification, what type of fracture is this?
. Hahn-Steinthal fracture (Type I)
. Kocher-Lorenz fracture (Type II)
. Broberg-Morrey comminuted fracture (Type III)
. McKee modification of Bryan and Morrey (Type IV)
. Jupiter Type V bicolumnar fracture

Correct Answer & Explanation

. McKee modification of Bryan and Morrey (Type IV)

Explanation

Coronal shear fractures of the distal humerus are classified by Bryan and Morrey: Type I (Hahn-Steinthal) is a large osseous capitellum fragment; Type II (Kocher-Lorenz) is an articular cartilage sleeve with minimal bone; Type III is comminuted. McKee added Type IV, which describes a single coronal shear fragment encompassing both the capitellum and the lateral aspect of the trochlea.

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