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2. Trauma MCQs

Practice Set 279 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 5561

Topic: 2. Trauma

A 30-year-old man sustains a highly comminuted proximal tibia fracture.

Twelve hours post-admission, he develops severe pain with passive toe stretch. His diastolic blood pressure is 75 mmHg and anterior compartment pressure is 55 mmHg. What is the most appropriate next step in management?

. Elevate the leg above the level of the heart
. Apply a long leg cast
. Administer intravenous mannitol
. Perform emergent four-compartment fasciotomies
. Observation and repeat pressures in 2 hours

Correct Answer & Explanation

. Perform emergent four-compartment fasciotomies

Explanation

The clinical picture is highly suspicious for acute compartment syndrome. The delta pressure (Diastolic BP - Compartment Pressure) is 75 - 55 = 20 mmHg. A delta pressure of 30 mmHg or less is an absolute indication for emergent four-compartment fasciotomy of the lower leg.

Question 5562

Topic: 2. Trauma

A 22-year-old male falls onto an outstretched hand. Follow-up MRI at 2 weeks confirms a nondisplaced fracture of the scaphoid proximal pole.

The blood supply to the proximal pole of the scaphoid is tenuous because the major nutrient vessels enter the scaphoid at which location?

. Through the proximal pole directly
. Distal to the waist and course proximally
. Volar to the tuberosity and course distally
. Through the radioscaphocapitate ligament
. Through the scapholunate interosseous ligament

Correct Answer & Explanation

. Distal to the waist and course proximally

Explanation

The primary blood supply to the scaphoid comes from the dorsal carpal branch of the radial artery, which enters the scaphoid at the dorsal ridge (distal to the waist) and supplies the proximal 80% of the bone via retrograde intraosseous flow. Fractures at the waist or proximal pole disrupt this supply, leading to high rates of avascular necrosis and nonunion.

Question 5563

Topic: 2. Trauma

A 32-year-old man sustains a closed spiral fracture of the distal third of his humerus (Holstein-Lewis fracture). He has a wrist drop on presentation.

Initial management with a functional fracture brace is selected. At what point is surgical exploration of the radial nerve indicated if there is no clinical or electromyographic improvement?

. 2 weeks
. 6 weeks
. 3-4 months
. 6-8 months
. Immediately

Correct Answer & Explanation

. 3-4 months

Explanation

Primary radial nerve palsy in a closed humeral shaft fracture is typically managed expectantly, as spontaneous recovery rates exceed 70%. If there is no clinical or EMG evidence of recovery by 3 to 4 months, surgical exploration of the nerve is indicated.

Question 5564

Topic: 2. Trauma

A 35-year-old skier sustains a Schatzker Type II (split-depression) tibial plateau fracture after a fall. Which of the following intra-articular structures is most frequently injured in conjunction with this specific fracture pattern?

. Medial meniscus
. Lateral meniscus
. Anterior cruciate ligament
. Posterior cruciate ligament
. Medial collateral ligament

Correct Answer & Explanation

. Lateral meniscus

Explanation

Schatzker Type II fractures involve a split-depression of the lateral tibial plateau. Associated soft tissue injuries are extremely common in tibial plateau fractures. The lateral meniscus is torn or entrapped in the fracture site in up to 40-50% of lateral plateau fractures (Schatzker I and II), making it the most frequently injured structure in this context.

Question 5565

Topic: 2. Trauma
A 30-year-old male is brought to the trauma bay with hemodynamic instability following a high-speed motorcycle crash. Pelvic radiographs show a severely displaced 'open-book' pelvic fracture (APC-III). An emergency pelvic binder is to be applied to reduce pelvic volume. To be biomechanically effective and stabilize the fracture, the binder should be centered directly over which of the following anatomical landmarks?
. Iliac crests
. Anterior superior iliac spines (ASIS)
. Greater trochanters
. Symphysis pubis
. Ischial tuberosities

Correct Answer & Explanation

. Greater trochanters

Explanation

To effectively reduce pelvic volume in an open-book fracture, the compressive force must be applied across the greater trochanters. Placing the binder higher over the iliac crests or ASIS can paradoxically widen the pelvis at the level of the symphysis pubis and fail to stabilize the posterior ring.

Question 5566

Topic: 2. Trauma

A 28-year-old man sustains a high-energy closed comminuted fracture of the tibial diaphysis.

Six hours post-injury, he complains of disproportionate leg pain that is severely exacerbated by passive stretch of the toes. The clinical suspicion for acute compartment syndrome is high. Which of the following pressure measurements provides the most widely accepted absolute indication for an emergency four-compartment fasciotomy?

. Absolute compartment pressure greater than 20 mm Hg
. Absolute compartment pressure greater than 25 mm Hg
. Delta pressure (Diastolic blood pressure minus Compartment pressure) less than 30 mm Hg
. Delta pressure (Mean arterial pressure minus Compartment pressure) less than 40 mm Hg
. Delta pressure (Systolic blood pressure minus Compartment pressure) less than 30 mm Hg

Correct Answer & Explanation

. Delta pressure (Diastolic blood pressure minus Compartment pressure) less than 30 mm Hg

Explanation

The diagnosis of acute compartment syndrome is primarily clinical, but when pressures are measured (especially in obtunded patients or equivocal cases), the 'Delta P' is the most reliable parameter. A Delta P of less than 30 mm Hg (calculated as Diastolic Blood Pressure minus the Absolute Compartment Pressure) indicates critically impaired tissue perfusion and is a firm indication for emergent fasciotomy. Relying solely on absolute pressure numbers (e.g., >30 mmHg) can lead to unnecessary fasciotomies in hypotensive or hypertensive patients.

Question 5567

Topic: 2. Trauma

A 35-year-old male sustains an isolated closed proximal third tibia fracture and is scheduled for intramedullary nailing.

The surgeon elects to use a suprapatellar approach instead of a traditional infrapatellar approach. According to current biomechanical and clinical literature, what is the primary advantage of the suprapatellar approach for this specific fracture pattern?

. Elimination of long-term anterior knee pain
. Easier maintenance of sagittal plane reduction during nail insertion
. Decreased risk of postoperative compartment syndrome
. Lower incidence of deep intra-articular infection
. Avoidance of the infrapatellar branch of the saphenous nerve

Correct Answer & Explanation

. Easier maintenance of sagittal plane reduction during nail insertion

Explanation

The suprapatellar approach allows the knee to be positioned in semi-extension (15-20 degrees of flexion) rather than the hyperflexion required for an infrapatellar approach. This positioning significantly neutralizes the deforming forces of the extensor mechanism (quadriceps), preventing the common apex anterior (procurvatum) deformity often seen when nailing proximal third tibia fractures, thereby making it easier to maintain sagittal alignment.

Question 5568

Topic: 2. Trauma

A 35-year-old male sustains an open fracture of the tibial diaphysis.

The orthopedic surgeon considers using recombinant human bone morphogenetic protein-2 (rhBMP-2) on a collagen sponge carrier to augment fracture healing. For which of the following indications is rhBMP-2 specifically FDA-approved in orthopedic trauma?

. Acute closed tibial shaft fractures treated with intramedullary nailing
. Acute open tibial shaft fractures treated with an intramedullary nail
. Recalcitrant nonunions of the femur
. Acute highly comminuted distal radius fractures
. Scaphoid nonunions with avascular necrosis

Correct Answer & Explanation

. Acute open tibial shaft fractures treated with an intramedullary nail

Explanation

In orthopedic trauma, rhBMP-2 (Infuse) is specifically FDA-approved for acute open tibial shaft fractures treated with an intramedullary nail, when applied within 14 days of the initial injury. It is not FDA-approved for closed tibia fractures, femoral nonunions, or upper extremity fractures.

Question 5569

Topic: Pelvic & Acetabular Trauma
A hemodynamically unstable 40-year-old male arrives in the trauma bay with an anteroposterior compression (APC) type III pelvic ring injury. The trauma team applies a pelvic circumferential compression device (binder). To achieve optimal biomechanical reduction of the pelvic volume and control hemorrhage, the binder must be centered over which specific anatomical landmarks?
. Anterior superior iliac spines
. Iliac crests
. Greater trochanters
. Symphysis pubis
. Umbilicus

Correct Answer & Explanation

. Greater trochanters

Explanation

For a pelvic binder to be mechanically effective in reducing pelvic volume (especially the posterior ring) and minimizing hemorrhage, it must be centered directly over the greater trochanters. Placement over the iliac crests is a common error and is ineffective at closing the pelvic ring; it can even exacerbate the deformity in some injury patterns.

Question 5570

Topic: 2. Trauma

A 32-year-old male is admitted with a highly comminuted, closed tibial shaft fracture.

Four hours after admission, he complains of unrelenting pain out of proportion to his injury and exquisite pain with passive stretch of his toes. Compartment pressures are measured. What pressure differential (Delta P) is considered the standard clinical threshold indicating the need for emergent four-compartment fasciotomy?

. Absolute compartment pressure > 20 mmHg
. Diastolic blood pressure minus compartment pressure < 30 mmHg
. Systolic blood pressure minus compartment pressure < 40 mmHg
. Mean arterial pressure minus compartment pressure < 30 mmHg
. Diastolic blood pressure minus compartment pressure > 45 mmHg

Correct Answer & Explanation

. Diastolic blood pressure minus compartment pressure < 30 mmHg

Explanation

Acute compartment syndrome is definitively diagnosed using a pressure differential (Delta P). A Delta P of less than 30 mmHg (calculated as Diastolic Blood Pressure minus the absolute Compartment Pressure) indicates inadequate tissue perfusion and is the standard threshold for emergent fasciotomy.

Question 5571

Topic: 2. Trauma

A 75-year-old woman sustains a displaced femoral neck fracture after a mechanical fall. Which of the following is the predominant blood supply to the femoral head that is at risk of disruption in this injury?

. Artery of the ligamentum teres
. Inferior gluteal artery
. Deep branch of the medial femoral circumflex artery
. Lateral femoral circumflex artery
. Profunda femoris artery

Correct Answer & Explanation

. Deep branch of the medial femoral circumflex artery

Explanation

The predominant blood supply to the adult femoral head is provided by the lateral epiphyseal artery, which is the terminal branch of the medial femoral circumflex artery (MFCA). This runs along the posterosuperior aspect of the femoral neck and is frequently disrupted in displaced femoral neck fractures, leading to a high risk of avascular necrosis.

Question 5572

Topic: 2. Trauma

A 22-year-old female soccer player sustains a twisting injury to her left knee. An AP radiograph demonstrates a small vertical avulsion fracture of the lateral tibial plateau, distal to the joint line. This fracture is considered pathognomonic for an injury to which of the following structures?

. Posterior cruciate ligament
. Anterior cruciate ligament
. Medial collateral ligament
. Lateral meniscus
. Popliteus tendon

Correct Answer & Explanation

. Anterior cruciate ligament

Explanation

The radiograph describes a Segond fracture, which is an avulsion fracture of the anterolateral aspect of the proximal tibia. It is typically associated with avulsion of the anterolateral ligament (ALL) or lateral capsular attachments and is highly predictive (pathognomonic) of an anterior cruciate ligament (ACL) tear.

Question 5573

Topic: 2. Trauma

A 45-year-old construction worker falls from a 15-foot scaffold and sustains a highly comminuted, intra-articular distal tibia (Pilon) fracture. Severe soft tissue swelling and fracture blisters are present on presentation. What is the most appropriate initial management for this injury?

. Immediate open reduction and internal fixation with dual plating
. Application of a spanning external fixator and delayed internal fixation
. Percutaneous screw fixation of the articular surface followed by early range of motion
. Primary ankle arthrodesis
. Closed reduction and long leg cast application

Correct Answer & Explanation

. Application of a spanning external fixator and delayed internal fixation

Explanation

High-energy Pilon fractures are often associated with significant soft tissue compromise. The standard of care is a staged protocol: initial application of a spanning external fixator (with or without fibular fixation) to stabilize the fracture and allow the soft tissues to recover (until the 'wrinkle sign' appears), followed by delayed definitive open reduction and internal fixation (ORIF) typically 10-21 days later. This minimizes the risk of catastrophic wound complications.

Question 5574

Topic: Pelvic & Acetabular Trauma
A 25-year-old male is involved in a high-speed motorcycle accident. Pelvic radiographs demonstrate symphysis pubis diastasis of 3.5 cm and widening of the anterior sacroiliac joints bilaterally. The posterior sacroiliac ligaments are determined to be intact. According to the Young-Burgess classification, what type of pelvic ring injury does this patient have?
. Lateral Compression Type I (LC-I)
. Lateral Compression Type II (LC-II)
. Anteroposterior Compression Type II (APC-II)
. Anteroposterior Compression Type III (APC-III)
. Vertical Shear (VS)

Correct Answer & Explanation

. Anteroposterior Compression Type II (APC-II)

Explanation

The injury mechanism is anteroposterior compression (APC). APC-II is characterized by disruption of the symphysis pubis (or anterior ring fractures) along with disruption of the anterior sacroiliac ligaments, sacrotuberous, and sacrospinous ligaments, while the posterior sacroiliac ligaments remain intact. This causes rotational instability but preserves vertical stability. APC-III involves complete disruption of both anterior and posterior SI ligaments, resulting in both rotational and vertical instability.

Question 5575

Topic: 2. Trauma

A 28-year-old man sustains a closed, highly comminuted tibia fracture. He is admitted for observation. Several hours later, he reports escalating leg pain that is out of proportion to his injury and is not relieved by opioid analgesics. Passive stretching of his toes elicits severe pain. Compartment pressures are measured. What criteria strongly indicates the need for an emergent four-compartment fasciotomy?

. Absolute compartment pressure greater than 15 mmHg
. Diastolic blood pressure minus compartment pressure (Delta p) less than 30 mmHg
. Systolic blood pressure minus compartment pressure less than 50 mmHg
. Compartment pressure equal to venous pressure
. Loss of palpable distal pulses

Correct Answer & Explanation

. Diastolic blood pressure minus compartment pressure (Delta p) less than 30 mmHg

Explanation

Acute compartment syndrome is a surgical emergency. The most reliable objective parameter indicating the need for fasciotomy is the Delta P, defined as the diastolic blood pressure minus the intracompartmental pressure. A Delta P of less than 30 mmHg (some authors use 30-40 mmHg) is highly indicative of compartment syndrome and dictates immediate fasciotomy. Loss of pulses is a very late and often absent sign.

Question 5576

Topic: Pelvic & Acetabular Trauma
A 45-year-old male presents after a motorcycle accident with an anteroposterior compression (APC) Type III pelvic ring injury. He is hemodynamically unstable despite initial resuscitation, massive transfusion protocol, and application of a pelvic binder. What is the next most appropriate step in management?
. Immediate application of a supra-acetabular external fixator
. Preperitoneal pelvic packing and/or angioembolization
. Open reduction and internal fixation of the pubic symphysis
. Retrograde urethrogram to rule out urologic injury
. Percutaneous sacroiliac screw fixation

Correct Answer & Explanation

. Preperitoneal pelvic packing and/or angioembolization

Explanation

In a hemodynamically unstable patient with an APC III pelvic ring injury who does not respond to a pelvic binder and initial fluid resuscitation, the source of bleeding is typically venous (presacral plexus) or arterial. Preperitoneal pelvic packing and/or angiography with embolization are the most appropriate next steps to achieve hemodynamic stability before any definitive orthopedic fixation.

Question 5577

Topic: 2. Trauma

A 72-year-old female sustains a 3-part proximal humerus fracture. She is indicated for an open reduction and internal fixation (ORIF) with a locking plate via a deltopectoral approach.

To avoid injury to the axillary nerve, what is the generally accepted 'danger zone' for plate placement distal to the tip of the greater tuberosity?

. 2 to 3 cm
. 3 to 4 cm
. 5 to 7 cm
. 8 to 10 cm
. 10 to 12 cm

Correct Answer & Explanation

. 5 to 7 cm

Explanation

The axillary nerve courses horizontally across the anterior aspect of the upper humerus. The average distance from the superior aspect of the greater tuberosity to the axillary nerve is approximately 5 to 7 cm. When placing a lateral locking plate for proximal humerus fractures, dissecting or passing the plate in this zone puts the nerve at high risk. Care must be taken to either slide the plate under the nerve or clearly identify and protect it.

Question 5578

Topic: 2. Trauma

A 35-year-old male is brought to the trauma bay after a severe fall from height. He is hypotensive and tachycardic. An AP pelvis radiograph demonstrates a vertically displaced left hemipelvis with severe disruption of the posterior sacroiliac complex and symphysis pubis.

If active arterial hemorrhage is identified on angiography, which vessel is most likely injured in this specific injury pattern?

. Obturator artery
. Internal pudendal artery
. Superior gluteal artery
. Corona mortis
. Inferior epigastric artery

Correct Answer & Explanation

. Superior gluteal artery

Explanation

Vertical shear pelvic fractures involve massive disruption of the posterior pelvic ring, including the sacrotuberous and sacrospinous ligaments. The superior gluteal artery exits the pelvis through the greater sciatic notch in close proximity to the sacroiliac joint and is the most commonly injured artery in vertical shear pelvic fractures. In contrast, APC (Anteroposterior Compression) injuries are more typically associated with injuries to the internal pudendal and obturator arteries.

Question 5579

Topic: 2. Trauma

A 40-year-old male sustains a high-energy Pilon fracture. Initial treatment consists of a spanning external fixator across the ankle joint.

Which of the following clinical findings best indicates that the soft tissue envelope has recovered sufficiently to permit definitive open reduction and internal fixation (ORIF)?

. Return of the 'wrinkle sign' on the anterior ankle skin
. Epithelialization of serous fracture blisters within 48 hours
. Resolution of the dependent rubor when the leg is elevated
. A palpable dorsalis pedis pulse overriding the external fixator
. Normalization of the erythrocyte sedimentation rate (ESR)

Correct Answer & Explanation

. Return of the 'wrinkle sign' on the anterior ankle skin

Explanation

In the staged management of high-energy Pilon fractures, definitive ORIF must be delayed until the soft tissue envelope has adequately healed to minimize the risk of wound complications and infection. The return of skin wrinkles (the 'wrinkle sign') indicates a significant reduction in interstitial edema and is the widely accepted clinical milestone for proceeding with definitive fixation, typically 10 to 21 days post-injury.

Question 5580

Topic: 2. Trauma
A 45-year-old male sustains a severe high-energy knee injury. Radiographs show a depressed, split fracture of the medial tibial plateau with extension into the intercondylar eminence (Schatzker Type IV). Which surgical approach is generally most critical to anatomically reduce and buttress the primary fracture fragment?
. Anterolateral approach
. Posteromedial approach
. Direct anterior parapatellar approach
. Posterolateral approach
. Direct medial approach

Correct Answer & Explanation

. Posteromedial approach

Explanation

Schatzker IV fractures involve the medial tibial plateau. The primary fracture fragment in medial plateau injuries typically displaces posteromedially due to the pull of the semimembranosus and the medial femoral condyle's biomechanics. A posteromedial surgical approach is required to properly visualize, reduce, and place an anti-glide buttress plate on the posteromedial apex of the fragment. An anterolateral approach is utilized for Schatzker I, II, and III (lateral plateau) fractures.

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