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2. Trauma MCQs

Practice Set 567 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 11321

Topic: Lower Extremity Trauma

The pivot shift test is pathognomonic for ACL insufficiency. During the maneuver, the tibia translates anteriorly in extension and reduces with a 'clunk' as the knee is flexed. Which anatomical structure is primarily responsible for generating the reducing force during flexion?

. Semimembranosus
. Popliteus
. Biceps femoris
. Iliotibial band
. Medial collateral ligament

Correct Answer & Explanation

. Semimembranosus

Explanation

In an ACL-deficient knee, the tibia subluxates anteriorly in extension. As the knee is flexed past 20-30 degrees, the Iliotibial (IT) band shifts from being an extensor of the knee to a flexor, falling posterior to the axis of rotation and creating a posterior vector that pulls the lateral tibial plateau backward into the reduced position.

Question 11322

Topic: 2. Trauma

A 32-year-old male sustains a closed tibial shaft fracture. Six hours post-admission, he develops severe leg pain out of proportion to the injury. Which physical examination finding is considered the most sensitive and earliest clinical indicator of acute compartment syndrome?

. Loss of peripheral pulses
. Pallor of the distal extremity
. Pain with passive stretch of the involved muscles
. Paresthesia in the first web space
. Firm, wooden feeling of the muscle compartments

Correct Answer & Explanation

. Loss of peripheral pulses

Explanation

Pain with passive stretch is widely considered the earliest and most sensitive clinical finding for acute compartment syndrome. Pulselessness and pallor are late and unreliable signs. Paresthesia is also reliable but usually occurs after the onset of pain on passive stretch.

Question 11323

Topic: Pelvic & Acetabular Trauma

In the Young-Burgess classification of pelvic ring injuries, which of the following fracture patterns is most characteristic of an Anteroposterior Compression Type II (APC II) injury?

. Symphysis pubis widening < 2.5 cm with intact posterior ligaments
. Symphysis pubis widening > 2.5 cm with disruption of anterior sacroiliac, sacrotuberous, and sacrospinous ligaments, but intact posterior sacroiliac ligaments
. Complete disruption of the symphysis pubis and both anterior and posterior sacroiliac ligaments
. Vertical displacement of the hemipelvis through the sacroiliac joint
. Internal rotation of the hemipelvis with a sacral crush injury

Correct Answer & Explanation

. Symphysis pubis widening < 2.5 cm with intact posterior ligaments

Explanation

An APC II injury involves an 'open book' pelvic ring with symphysis diastasis >2.5 cm and disruption of the anterior SI ligaments, sacrotuberous, and sacrospinous ligaments. The strong posterior SI ligaments remain intact, maintaining vertical stability but resulting in rotational instability.

Question 11324

Topic: 2. Trauma

A 35-year-old man sustains a closed, displaced fracture of the distal third of the humeral shaft (Holstein-Lewis fracture). On examination, he is unable to extend his wrist or fingers. He undergoes closed reduction and splinting, but post-reduction examination reveals the onset of a new, complete radial nerve palsy. What is the most appropriate next step in management?

. Immediate surgical exploration and nerve repair/release
. Observation with serial EMGs starting at 6 weeks
. Administration of high-dose intravenous corticosteroids
. Application of a functional fracture brace and physical therapy
. Ultrasound-guided aspiration of the fracture hematoma

Correct Answer & Explanation

. Immediate surgical exploration and nerve repair/release

Explanation

While primary radial nerve palsies presentingat the timeof closed humeral shaft fractures are generally observed, asecondaryradial nerve palsy that develops or worsensafterclosed reduction attempts indicates possible iatrogenic entrapment or laceration of the nerve between the fracture fragments. This is an absolute indication for immediate surgical exploration.

Question 11325

Topic: Lower Extremity Trauma

The pivot shift test is utilized to evaluate rotatory instability of the knee. Biomechanically, what occurs during a positive pivot shift test as the knee is brought from full extension into flexion?

. The medial tibial plateau reduces from an anteriorly subluxated position
. The lateral tibial plateau reduces from an anteriorly subluxated position
. The lateral tibial plateau subluxates anteriorly
. The patella subluxates laterally out of the trochlea
. The posterior tibia reduces from a posteriorly subluxated position

Correct Answer & Explanation

. The medial tibial plateau reduces from an anteriorly subluxated position

Explanation

In an ACL-deficient knee, the lateral tibial plateau rests in an anteriorly subluxated position in full extension. As the knee flexes past 20-30 degrees, the iliotibial band transitions from an extensor to a flexor, applying a posterior vector that suddenly reduces the lateral plateau with a palpable clunk.

Question 11326

Topic: Lower Extremity Trauma

During the pivot shift test for anterior cruciate ligament (ACL) insufficiency, the examiner applies a valgus stress and internal rotation while flexing the knee. The distinct clunk observed at 20-30 degrees of flexion represents which biomechanical event?

. Subluxation of the medial tibial plateau
. Reduction of the anteriorly subluxated lateral tibial plateau by the iliotibial band
. Subluxation of the lateral tibial plateau
. Reduction of the medial tibial plateau by the pes anserine
. Impingement of the ACL stump against the PCL

Correct Answer & Explanation

. Subluxation of the medial tibial plateau

Explanation

During the pivot shift test, the tibia is subluxated anteriorly in extension. As the knee flexes past 20-30 degrees, the iliotibial band transitions from an extensor to a flexor, rapidly reducing the lateral tibial plateau.

Question 11327

Topic: 2. Trauma
A 25-year-old male sustains a high-energy vertical shear femoral neck fracture (Pauwels type III). Which of the following internal fixation constructs provides the greatest biomechanical stability against the high shear forces inherent to this fracture pattern?
. Three parallel cancellous screws
. Cannulated screws in an inverted triangle configuration
. Dynamic hip screw (DHS) alone
. Sliding hip screw with an anti-rotation cancellous screw
. Proximal femoral locking plate

Correct Answer & Explanation

. Sliding hip screw with an anti-rotation cancellous screw

Explanation

Pauwels type III femoral neck fractures have a vertical fracture line (angle >50 degrees), which subjects the fracture to high shear forces and a high risk of varus collapse. A fixed-angle device, such as a sliding hip screw (with an additional anti-rotation screw) or a cephalomedullary nail, provides superior biomechanical stability against these shear forces compared to multiple cancellous screws.

Question 11328

Topic: 2. Trauma

A 22-year-old female athlete suffers a twisting injury to her knee. Radiographs reveal a small elliptical bone fragment adjacent to the lateral tibial plateau (Segond fracture). This radiographic finding indicates an avulsion of which of the following structures?

. Anterior cruciate ligament
. Posterior cruciate ligament
. Iliotibial band
. Anterolateral ligament
. Lateral collateral ligament

Correct Answer & Explanation

. Anterior cruciate ligament

Explanation

A Segond fracture is a cortical avulsion fracture off the lateral tibial plateau and is pathognomonic for an anterior cruciate ligament (ACL) tear. The avulsed bony fragment itself specifically represents the tibial attachment of the anterolateral ligament (ALL) and the lateral capsular ligament.

Question 11329

Topic: 2. Trauma

A 40-year-old male sustains a high-energy Schatzker VI tibial plateau fracture. He is admitted for observation while awaiting soft tissue swelling to decrease. Which of the following clinical findings is the most reliable early indicator of an impending acute compartment syndrome?

. Loss of distal pedal pulses
. Paresthesias in the first web space
. Pain out of proportion elicited by passive stretch of the toes
. Pallor and poikilothermia of the foot
. Motor paralysis of the extensor hallucis longus

Correct Answer & Explanation

. Loss of distal pedal pulses

Explanation

Pain out of proportion to the injury, particularly pain elicited by passive stretch of the muscles in the involved compartment, is the earliest and most sensitive clinical sign of acute compartment syndrome. The '5 Ps' (pallor, pulselessness, paresthesias, paralysis) are typically late and unreliable signs.

Question 11330

Topic: 2. Trauma
A 35-year-old male is brought to the trauma bay after a motorcycle collision. He is hypotensive and tachycardic. Pelvic radiographs show an Anteroposterior Compression Type III (APC III) injury with a widely displaced symphysis pubis and disrupted sacroiliac joints. When applying a non-invasive pelvic binder to reduce the pelvic volume, over which anatomic landmarks should the binder be centered?
. Superior pubic ramus
. Symphysis pubis
. Greater trochanters
. Iliac crests
. Anterior superior iliac spines (ASIS)

Correct Answer & Explanation

. Greater trochanters

Explanation

For effective reduction of pelvic ring volume and hemorrhage control in an 'open book' (APC) pelvic fracture, a pelvic binder or sheet must be centered directly over the greater trochanters. Placing it over the iliac crests is a common error and can paradoxically open the pelvis further or fail to provide adequate mechanical compression of the posterior venous plexus.

Question 11331

Topic: Pelvic & Acetabular Trauma
A 40-year-old male presents with a hemodynamically unstable APC-III pelvic ring injury following a motorcycle collision. Despite a properly applied pelvic binder and massive transfusion protocol, he remains profoundly hypotensive. What is the most common anatomical source of massive hemorrhage in this fracture pattern?
. Superior gluteal artery
. Internal pudendal artery
. Presacral venous plexus
. External iliac artery
. Obturator artery

Correct Answer & Explanation

. Presacral venous plexus

Explanation

Up to 80% of massive hemorrhage in pelvic ring injuries is venous in origin, most frequently arising from the presacral venous plexus. While arterial bleeding (such as from the superior gluteal artery) can be catastrophic, it is more commonly associated with posterior ring disruptions and represents a smaller percentage of overall pelvic bleeding.

Question 11332

Topic: 2. Trauma

A 32-year-old male sustains a closed talar neck fracture following a motor vehicle collision. Six weeks after open reduction and internal fixation, an AP radiograph of the ankle reveals a subchondral radiolucent band in the dome of the talus (Hawkins sign). What does this radiographic finding indicate?

. Impending avascular necrosis of the talar body
. Revascularization and intact blood supply to the talar body
. Nonunion of the talar neck
. Post-traumatic osteoarthritis of the tibiotalar joint
. Infection of the talar dome

Correct Answer & Explanation

. Impending avascular necrosis of the talar body

Explanation

The Hawkins sign is a subchondral radiolucent band representing subchondral osteopenia. It indicates that the blood supply to the talar body is intact and actively resorbing bone, making avascular necrosis highly unlikely.

Question 11333

Topic: 2. Trauma

A 45-year-old male is admitted with a highly comminuted tibia fracture. He develops escalating leg pain requiring increasing doses of narcotics. Which pressure measurement confirms an absolute indication for emergency four-compartment fasciotomy?

. Absolute intracompartmental pressure of 20 mmHg
. Absolute intracompartmental pressure of 25 mmHg
. Mean arterial pressure minus intracompartmental pressure < 30 mmHg
. Systolic blood pressure minus intracompartmental pressure < 30 mmHg
. Diastolic blood pressure minus intracompartmental pressure < 30 mmHg

Correct Answer & Explanation

. Absolute intracompartmental pressure of 20 mmHg

Explanation

Compartment syndrome is a clinical diagnosis, but when pressures are measured, a delta pressure (Diastolic BP minus compartment pressure) of less than 30 mmHg is considered a definitive indication for fasciotomy.

Question 11334

Topic: 2. Trauma

Following reamed intramedullary nailing of an isolated closed tibial shaft fracture, what is the most frequently reported long-term complication?

. Nonunion
. Malunion
. Anterior knee pain
. Deep infection
. Compartment syndrome

Correct Answer & Explanation

. Nonunion

Explanation

Anterior knee pain is the most common complication following intramedullary nailing of the tibia, occurring in up to 40-50% of patients regardless of whether a parapatellar or transtendinous approach is used.

Question 11335

Topic: 2. Trauma

A 32-year-old male undergoes reamed intramedullary nailing for a closed tibial shaft fracture. In the postoperative period and after union is achieved, what is the most frequently reported long-term complication associated with this specific surgical intervention?

. Anterior knee pain
. Tibial nonunion
. Deep surgical site infection
. Anterior compartment syndrome
. Malunion in valgus

Correct Answer & Explanation

. Anterior knee pain

Explanation

Anterior knee pain is the most common complication following intramedullary nailing of tibial shaft fractures, occurring in up to 40-50% of patients. It occurs regardless of whether a parapatellar or transtendinous approach is used.

Question 11336

Topic: 2. Trauma

A 40-year-old female undergoes open reduction and internal fixation of a displaced radial shaft fracture using a lag screw and neutralization plate, providing absolute stability. By which biological mechanism will this fracture primarily heal?

. Endochondral ossification
. Intramembranous ossification
. Primary bone healing via cutting cones
. Callus formation and remodeling
. Chondrogenesis and subsequent calcification

Correct Answer & Explanation

. Endochondral ossification

Explanation

Absolute stability (e.g., lag screw and plate) minimizes interfragmentary strain and suppresses callus formation. Healing occurs via primary bone healing, characterized by osteoclastic cutting cones followed by osteoblastic bone deposition directly across the fracture line.

Question 11337

Topic: 2. Trauma

A 25-year-old male is admitted with a highly comminuted closed tibial plateau fracture. Which of the following clinical findings is the earliest and most sensitive indicator of developing acute compartment syndrome in the affected leg?

. Loss of distal pedal pulses
. Capillary refill time greater than 3 seconds
. Paresthesias in the first web space
. Pain out of proportion aggravated by passive stretch
. Flaccid paralysis of the anterior compartment musculature

Correct Answer & Explanation

. Loss of distal pedal pulses

Explanation

Pain out of proportion to the injury, especially pain exacerbated by passive stretch of the involved compartment's muscles, is the earliest and most reliable clinical sign of acute compartment syndrome. Pulselessness and paralysis are very late and ominous signs.

Question 11338

Topic: 2. Trauma
A 45-year-old is brought to the trauma bay following a crush injury. Radiographs show an anteroposterior compression type III (APC III) open book pelvic ring injury. If this patient becomes rapidly hemodynamically unstable, what is the most common anatomical source of major pelvic hemorrhage?
. Superior gluteal artery
. Obturator artery
. Internal pudendal artery
. Presacral venous plexus
. External iliac artery

Correct Answer & Explanation

. Presacral venous plexus

Explanation

While arterial bleeding (such as from the superior gluteal or internal pudendal arteries) can be life-threatening and require embolization, the vast majority (approximately 80-90%) of pelvic hemorrhage in severe pelvic ring fractures originates from the presacral venous plexus and bleeding cancellous bone.

Question 11339

Topic: 2. Trauma
A 30-year-old male is brought to the trauma bay hemodynamically unstable following a motorcycle collision. Pelvic radiographs reveal an anteroposterior compression (APC III) injury with a widened symphysis pubis and disrupted sacroiliac joints. Where should a pelvic binder be applied initially?
. Over the iliac crests
. Centered directly over the greater trochanters
. Directly over the pubic symphysis
. Around the mid-shaft of the femurs
. Superior to the anterior superior iliac spines (ASIS)

Correct Answer & Explanation

. Centered directly over the greater trochanters

Explanation

A pelvic binder must be placed centered over the greater trochanters to effectively close the pelvic volume and stabilize the fracture. Placement over the iliac crests is incorrect and can act as a fulcrum, exacerbating the pelvic deformity.

Question 11340

Topic: 2. Trauma

A 32-year-old male sustains a comminuted tibia fracture. Four hours post-injury, he complains of severe leg pain out of proportion to the injury. Which of the following absolute measurements or calculations provides the most reliable indication for emergent fasciotomy?

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

Correct Answer & Explanation

. Absolute compartment pressure > 20 mmHg

Explanation

The Delta P threshold is the most reliable parameter for diagnosing acute compartment syndrome, defined as the diastolic blood pressure minus the compartment pressure being less than 30 mmHg. This calculation accounts for systemic perfusion better than absolute pressure values.

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