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2. Trauma MCQs

Practice Set 557 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 11121

Topic: 2. Trauma

When internally fixing a proximal pole scaphoid fracture or nonunion with a headless compression screw, what is the primary biomechanical advantage of utilizing a dorsal percutaneous or mini-open approach rather than a volar approach?

. It allows for an opening wedge structural graft to be placed more easily.
. It permits the screw to be placed more centrally along the central axis of the scaphoid.
. It avoids injury to the radioscaphocapitate ligament entirely.
. It relies on the robust volar blood supply for healing.
. It inherently corrects the humpback deformity without grafting.

Correct Answer & Explanation

. It allows for an opening wedge structural graft to be placed more easily.

Explanation

The scaphoid is curved volarly. A volar approach often forces the screw to enter eccentrically (volarly and distally) to avoid the trapezium, leading to suboptimal peripheral placement. A dorsal approach allows the guidewire and screw to be placed directly down the longest mechanical, central axis of the scaphoid, providing superior biomechanical fixation, which is crucial for small proximal pole fragments.

Question 11122

Topic: 2. Trauma

A 24-year-old male has a proximal pole scaphoid nonunion with avascular necrosis and a collapsed humpback deformity. Previous 1,2 ICSRA bone grafting failed. What is the most appropriate surgical intervention to achieve union and restore scaphoid morphology?

. Medial femoral condyle free vascularized bone graft
. Vascularized pedicled graft from the volar radius (PQ pedicle)
. Proximal row carpectomy
. Scaphoid excision and four-corner fusion
. Non-vascularized iliac crest bone graft

Correct Answer & Explanation

. Medial femoral condyle free vascularized bone graft

Explanation

Free vascularized bone grafts, such as the medial femoral condyle (MFC) flap, are indicated for proximal pole nonunions with AVN and structural collapse, especially after failed pedicled grafting. The MFC provides robust structural support and reliable blood supply.

Question 11123

Topic: 2. Trauma

The major blood supply to the proximal pole of the scaphoid enters the bone at which anatomical location, making proximal pole fractures particularly susceptible to avascular necrosis?

. Volar aspect of the distal pole
. Dorsal ridge via branches of the radial artery
. Scaphoid tubercle via the superficial palmar arch
. Palmar radiocarpal ligaments
. Directly through the radioscaphoid articular surface

Correct Answer & Explanation

. Volar aspect of the distal pole

Explanation

The scaphoid receives 70-80% of its vascularity from the dorsal carpal branch of the radial artery, which enters at the dorsal ridge and supplies the proximal pole in a retrograde fashion. This retrograde flow makes proximal fractures highly prone to ischemia.

Question 11124

Topic: 2. Trauma

An untreated scaphoid waist fracture often leads to a humpback deformity. Which of the following best describes the resulting carpal malalignment?

. The distal fragment flexes with the trapezium and trapezoid, while the proximal fragment extends with the lunate
. The distal fragment extends with the lunate, while the proximal fragment flexes
. Both fragments flex leading to a volar intercalated segment instability (VISI)
. The lunate displaces volarly and the capitate displaces dorsally
. The entire scaphoid translates ulnarly overriding the lunate

Correct Answer & Explanation

. The distal fragment flexes with the trapezium and trapezoid, while the proximal fragment extends with the lunate

Explanation

In a scaphoid waist nonunion, the distal scaphoid fragment tends to flex volarly along with the distal carpal row. The proximal fragment extends with the lunate, leading to a dorsal intercalated segment instability (DISI) pattern.

Question 11125

Topic: 2. Trauma

When comparing proximal row carpectomy (PRC) to scaphoid excision and four-corner fusion (4CF) for the treatment of advanced carpal collapse, which of the following represents a known advantage of PRC?

. Higher ultimate grip strength
. Sparing of the capitolunate joint
. Lack of potential for nonunion of the arthrodesis site
. Better long-term preservation of the radiolunate joint
. Ability to perform the procedure in cases of severe capitate head arthritis

Correct Answer & Explanation

. Higher ultimate grip strength

Explanation

Because PRC does not involve an arthrodesis, it avoids the complication of nonunion, allows for earlier postoperative mobilization, and is technically simpler compared to a four-corner fusion.

Question 11126

Topic: 2. Trauma

A patient with a scaphoid waist nonunion develops a progressive humpback deformity. Which of the following radiographic angles best quantifies this specific deformity on a standard lateral radiograph?

. Radiolunate angle > 15 degrees
. Scapholunate angle > 60 degrees
. Intrascaphoid angle > 45 degrees
. Capitolunate angle > 20 degrees
. Radioscaphoid angle < 30 degrees

Correct Answer & Explanation

. Radiolunate angle > 15 degrees

Explanation

The intrascaphoid angle is measured on a lateral radiograph between lines drawn perpendicular to the proximal and distal articular surfaces. An angle greater than 45 degrees defines a humpback deformity, indicating volar collapse.

Question 11127

Topic: 2. Trauma

A 28-year-old male requires surgical correction of a chronic scaphoid waist nonunion with a prominent humpback deformity and no MRI evidence of avascular necrosis. Which of the following surgical approaches and grafting techniques is most appropriate?

. Dorsal approach with a 1,2 ICSRA vascularized bone graft
. Volar approach with a structural anterior wedge corticocancellous graft
. Dorsal approach with non-structural cancellous bone graft
. Volar approach with a medial femoral condyle free flap
. Percutaneous screw fixation without bone grafting

Correct Answer & Explanation

. Dorsal approach with a 1,2 ICSRA vascularized bone graft

Explanation

A volar approach allows direct access to open the volar fracture site and correct the flexion deformity by inserting a structural corticocancellous wedge graft, restoring native scaphoid length.

Question 11128

Topic: 2. Trauma

During osteosynthesis of a scaphoid waist nonunion, what is the biomechanically optimal position for the placement of a headless compression screw?

. Eccentric and dorsal
. Eccentric and volar
. Central down the longitudinal axis of the scaphoid
. Perpendicular to the primary fracture line
. Parallel to the radioscaphoid joint line

Correct Answer & Explanation

. Eccentric and dorsal

Explanation

Central placement of a headless compression screw down the longitudinal axis of the scaphoid provides the greatest biomechanical stability, maximizing stiffness and time to failure under bending loads.

Question 11129

Topic: 2. Trauma

A free medial femoral condyle (MFC) vascularized bone graft is planned for a recalcitrant scaphoid proximal pole nonunion with confirmed avascular necrosis. The surgeon must dissect which of the following source vessels to serve as the vascular pedicle for this specific graft?

. Lateral circumflex femoral artery
. Sural artery
. Descending genicular artery
. Medial superior genicular artery
. Popliteal artery directly

Correct Answer & Explanation

. Lateral circumflex femoral artery

Explanation

The free medial femoral condyle (MFC) vascularized bone graft is supplied by the articular branch of the descending genicular artery, with the superomedial genicular artery serving as a secondary or variant supply. This provides robust antegrade flow ideal for treating avascular nonunions.

Question 11130

Topic: Lower Extremity Trauma

A 10-year-old girl is evaluated for an idiopathic limb length discrepancy (LLD). Radiographs indicate her right lower extremity is 20 mm longer than her left. Her bone age matches her chronological age. Utilizing the Menelaus rule of thumb for growth remaining, at what age should an isolated right distal femoral epiphysiodesis be performed to equalize her leg lengths at maturity?

. 10.5 years
. 11.8 years
. 12.5 years
. 13.2 years
. 14.0 years

Correct Answer & Explanation

. 10.5 years

Explanation

According to the Menelaus method (Rule of Thumb), girls complete longitudinal growth at age 14 (boys at 16). The distal femur grows at a rate of approximately 3/8 inch (9 mm or ~1 cm) per year. The proximal tibia grows at 1/4 inch (6 mm) per year. To correct a 20 mm (2 cm) discrepancy using ONLY the distal femur, 20 mm / 9 mm/year = 2.22 years of growth are required. Therefore, the epiphysiodesis should be performed 2.22 years before growth ceases: 14 - 2.2 = 11.8 years of age.

Question 11131

Topic: 2. Trauma

A 6-year-old girl falls off monkey bars and sustains a widely displaced extension-type supracondylar fracture of the humerus. On presentation, her hand is pink and warm, but the radial pulse is absent. Capillary refill is 2 seconds. The anterior interosseous nerve (AIN) function is decreased. She undergoes prompt closed reduction and percutaneous pinning. Post-reduction, the hand remains pink and warm, but the radial pulse remains absent. What is the next step in management?

. Immediate vascular surgery consultation for brachial artery exploration
. Observation and admission for 24-48 hour monitoring
. Immediate open reduction and removal of entrapped periosteum
. Arteriography to evaluate the brachial artery
. Fasciotomy for suspected compartment syndrome

Correct Answer & Explanation

. Immediate vascular surgery consultation for brachial artery exploration

Explanation

In the setting of a 'pulseless, pink' hand after closed reduction and pinning of a pediatric supracondylar humerus fracture, the standard of care is close observation and admission for 24-48 hours. The collateral circulation is typically sufficient to perfuse the hand. Vascular exploration is indicated if the hand becomes cold, pale, and pulseless (ischemic) despite reduction. AIN palsy is the most common nerve injury in extension-type fractures and usually resolves spontaneously.

Question 11132

Topic: 2. Trauma

A 3-year-old boy presents with an isolated, closed spiral fracture of the midshaft of the femur after falling from a toddler bed. He weighs 16 kg (35 lbs). The fracture is shortened by 1 cm. What is the most appropriate definitive management?

. Immediate application of a single-leg hip spica cast
. Flexible intramedullary nailing
. Rigid antegrade intramedullary nailing
. External fixation
. Open reduction and internal fixation with a compression plate

Correct Answer & Explanation

. Immediate application of a single-leg hip spica cast

Explanation

For pediatric femoral shaft fractures in children under 5 years of age and weighing less than 50 lbs (22.7 kg), early hip spica casting is the standard of care. It provides excellent outcomes with minimal risk of complications. Flexible intramedullary nails are typically indicated for children aged 5 to 11 years. Rigid nailing is contraindicated due to the risk of avascular necrosis of the femoral head from piriformis fossa entry.

Question 11133

Topic: 2. Trauma

A 3-year-old girl is diagnosed with a diaphyseal femur fracture after a low-energy fall. She weighs 18 kg (40 lbs). Which of the following is the most appropriate definitive treatment?

. Pavlik harness
. Spica cast
. Flexible intramedullary nailing
. Rigid locked intramedullary nailing
. External fixation

Correct Answer & Explanation

. Pavlik harness

Explanation

For children aged 1 to 5 years weighing less than 20 kg (44 lbs) with an isolated diaphyseal femur fracture, early hip spica casting is the gold standard. Flexible intramedullary nailing is typically reserved for children aged 5 to 11 years.

Question 11134

Topic: 2. Trauma

A 2-year-old boy presents with a history of recurrent fractures following minimal trauma. Physical exam reveals blue sclerae and delayed dentition. Which of the following accurately describes the underlying molecular defect?

. Defective osteoclastic resorption
. Quantitative or qualitative defect in Type I collagen
. Mutation in the cartilage oligomeric matrix protein
. Impaired mineralization of osteoid
. Defect in the mineralization of the provisional calcification zone

Correct Answer & Explanation

. Defective osteoclastic resorption

Explanation

The patient's presentation of multiple fragility fractures, blue sclerae, and dentinogenesis imperfecta is classic for Osteogenesis Imperfecta (OI). OI is caused by mutations in the COL1A1 or COL1A2 genes, resulting in defective Type I collagen synthesis.

Question 11135

Topic: Pelvic & Acetabular Trauma
A hemodynamically unstable 35-year-old male is brought to the ED after a motorcycle collision. Radiographs show an APC-III pelvic ring injury. Despite a pelvic binder and 2 units of uncrossmatched blood, the patient's BP remains 75/40. FAST is negative. What is the most rapid and definitive surgical intervention to control the primary source of pelvic bleeding?
. Immediate REBOA placement
. Immediate anterior open reduction and internal fixation
. Preperitoneal pelvic packing
. Retrograde urethrogram
. Sacroiliac screw fixation

Correct Answer & Explanation

. Preperitoneal pelvic packing

Explanation

In a hemodynamically unstable patient with an unstable pelvic fracture and negative FAST, the source of bleeding is likely the venous presacral plexus or cancellous bone (80% of cases). If instability persists despite binder and resuscitation, preperitoneal pelvic packing or angiography with embolization is indicated. Preperitoneal packing is favored for rapid control of venous bleeding in the emergent setting.

Question 11136

Topic: 2. Trauma

A 22-year-old male falls on an outstretched hand and sustains a fracture through the proximal pole of the scaphoid. Why is this specific fracture pattern at a very high risk for avascular necrosis?

. The primary blood supply enters distally and flows in a retrograde fashion to the proximal pole
. The scaphoid relies entirely on diffusion from synovial fluid
. The primary blood supply enters dorsally along the proximal pole and flows distally
. The proximal pole is exclusively supplied by the ulnar artery
. The palmar carpal branch of the radial artery enters the proximal pole directly

Correct Answer & Explanation

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

Explanation

The scaphoid receives 70-80% of its blood supply from the dorsal carpal branch of the radial artery, which enters the scaphoid at the dorsal ridge (near the waist/distal pole) and provides intraosseous retrograde flow to the proximal pole. Fractures at the proximal pole disrupt this retrograde supply, leading to a high rate of avascular necrosis and nonunion.

Question 11137

Topic: 2. Trauma

A 28-year-old male sustains a closed tibia fracture and is at risk for compartment syndrome. Which of the following localized physiological factors shifts the oxyhemoglobin dissociation curve to the right, facilitating oxygen offloading in the ischemic tissues?

. Decreased temperature
. Decreased 2,3-DPG
. Increased pH
. Increased pCO2
. Decreased hydrogen ion concentration

Correct Answer & Explanation

. Decreased temperature

Explanation

In ischemic tissues (such as in early compartment syndrome), there is localized hypoxia and accumulation of CO2 and lactic acid (acidosis). Increased pCO2, increased hydrogen ions (decreased pH), increased temperature, and increased 2,3-DPG all shift the oxyhemoglobin dissociation curve to the right (Bohr effect), decreasing hemoglobin's affinity for oxygen and promoting oxygen release to the tissues.

Question 11138

Topic: 2. Trauma

What is the primary surgical sequence in the standard staged management of a high-energy, closed distal tibia intra-articular (Pilon) fracture with severe soft tissue swelling and fracture blisters?

. Immediate open reduction and internal fixation of both tibia and fibula
. Fibular fixation and placement of a spanning external fixator, followed by delayed definitive tibial fixation
. Immediate intramedullary nailing of the tibia with percutaneous screw fixation of the articular surface
. Casting until swelling subsides followed by definitive internal fixation
. Immediate primary amputation

Correct Answer & Explanation

. Immediate open reduction and internal fixation of both tibia and fibula

Explanation

The standard of care for high-energy pilon fractures with compromised soft tissues is a staged protocol: initial management with a spanning external fixator across the ankle joint and open reduction and internal fixation (ORIF) of the fibula (to restore length and rotation), followed by definitive ORIF of the tibia 10-21 days later once soft tissue swelling has subsided (positive 'wrinkle sign') and fracture blisters have epithelized.

Question 11139

Topic: 2. Trauma

The scaphoid bone is highly susceptible to avascular necrosis following fracture. The predominant blood supply to the proximal pole of the scaphoid enters the bone through which of the following areas?

. Volar distal pole
. Dorsal distal ridge
. Volar proximal pole
. Dorsal proximal pole
. Scaphoid tubercle

Correct Answer & Explanation

. Volar distal pole

Explanation

The scaphoid receives its primary blood supply from branches of the radial artery. The major vessels enter the dorsal ridge (dorsal distal half) of the scaphoid and travel retrogradely to supply the proximal pole. Because of this retrograde blood supply, fractures through the waist or proximal pole disrupt the blood flow to the proximal fragment, significantly increasing the risk of avascular necrosis and nonunion.

Question 11140

Topic: 2. Trauma

A 32-year-old man presents with a closed comminuted tibial shaft fracture following a motorcycle collision. He is complaining of excruciating leg pain out of proportion to the injury. His blood pressure is 110/65 mmHg. Intracompartmental pressure testing of the anterior compartment of the leg reads 45 mmHg. What is the Delta P and the recommended management?

. Delta P is 20 mmHg; proceed with emergent four-compartment fasciotomy
. Delta P is 65 mmHg; continue close clinical observation
. Delta P is 45 mmHg; proceed with single-incision anterior fasciotomy
. Delta P is 20 mmHg; apply a tight compressive dressing and elevate above heart level
. Delta P is 45 mmHg; administer intravenous mannitol

Correct Answer & Explanation

. Delta P is 20 mmHg; proceed with emergent four-compartment fasciotomy

Explanation

Delta P is calculated as Diastolic Blood Pressure minus Intracompartmental Pressure. In this patient, 65 mmHg - 45 mmHg = 20 mmHg. A Delta P of less than 30 mmHg in the setting of clinical signs is an absolute indication for emergent four-compartment fasciotomy of the leg to prevent irreversible ischemic necrosis.

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