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 12241
Topic: 2. Trauma
A 32-year-old male sustains a closed tibial shaft fracture. His diastolic blood pressure is 80 mmHg. What absolute intracompartmental pressure or delta pressure threshold is the most accepted indication for a four-compartment fasciotomy?
Correct Answer & Explanation
. Delta pressure < 30 mmHg
Explanation
A delta pressure (diastolic blood pressure minus intracompartmental pressure) of less than 30 mmHg is the most widely accepted and reliable indication for fasciotomy. Absolute pressure thresholds are less accurate due to physiological variations in systemic perfusion pressure.
Question 12242
Topic: 2. Trauma
A 32-year-old male sustains an open tibia fracture in a motorcycle crash. The wound measures 8 cm, involves extensive muscle stripping, and requires a free rotational flap for coverage. There is no major arterial injury. According to the Gustilo-Anderson classification, what is the grade of this injury?
Correct Answer & Explanation
. Type IIIB
Explanation
Gustilo-Anderson Type IIIB fractures are open fractures with extensive soft-tissue injury, periosteal stripping, and bone exposure, requiring a local or free flap for soft tissue coverage. Type IIIA can be covered primarily without a flap. Type IIIC involves an arterial injury requiring repair for limb salvage.
Question 12243
Topic: 2. Trauma
Which of the following constructs promotes primary (direct) bone healing without callus formation?
Correct Answer & Explanation
. Lag screw and neutralization plate for a fibula fracture
Explanation
Primary (direct) bone healing occurs under conditions of absolute stability, which is achieved by interfragmentary compression. A lag screw and neutralization plate provide absolute stability, preventing micro-motion and allowing for Haversian remodeling without visible callus. Options like nails, bridge plates, external fixators, and casts provide relative stability, leading to secondary bone healing via callus formation.
Question 12244
Topic: 2. Trauma
A patient undergoes a four-compartment fasciotomy for acute compartment syndrome of the leg following a tibia fracture. Which of the following muscles is located in the deep posterior compartment?
Correct Answer & Explanation
. Flexor hallucis longus
Explanation
The deep posterior compartment of the leg contains the tibialis posterior, flexor digitorum longus, and flexor hallucis longus muscles. The gastrocnemius and soleus reside in the superficial posterior compartment. The peroneus brevis is lateral, and the extensor digitorum longus is anterior.
Question 12245
Topic: 2. Trauma
A 24-year-old male sustains bilateral closed femur fractures in an MVC. On hospital day 2, he develops confusion, tachypnea, and a petechial rash over his axillae. Which of the following is considered the primary biochemical mechanism for the pulmonary manifestations of his condition?
Correct Answer & Explanation
. Release of free fatty acids causing direct endothelial injury to the pulmonary capillaries
Explanation
The patient is presenting with Fat Embolism Syndrome (FES). According to the biochemical theory of FES, marrow fat enters the bloodstream and is degraded by tissue lipases into free fatty acids (FFAs). These FFAs are highly toxic to the pulmonary capillary endothelium, precipitating Acute Respiratory Distress Syndrome (ARDS).
Question 12246
Topic: Lower Extremity Trauma
A surgeon decides to increase the diameter of a solid titanium intramedullary nail from 10 mm to 12 mm. By what approximate factor will the torsional rigidity of the nail increase?
Correct Answer & Explanation
. 2.07
Explanation
The torsional rigidity of a solid cylinder is proportional to the fourth power of its radius (r^4). Increasing the diameter by a factor of 1.2 increases the rigidity by 1.2^4, which is approximately 2.07.
Question 12247
Topic: 2. Trauma
A surgeon utilizes a bridge plating technique for a comminuted midshaft femur fracture. To optimize secondary bone healing via callus formation, the surgeon deliberately skips screw holes near the fracture site. Increasing the 'working length' of this construct has which specific biomechanical effect?
Correct Answer & Explanation
. Decreases the interfragmentary strain
Explanation
The working length is the distance between the innermost screws on either side of a fracture. Increasing the working length increases the construct's flexibility, thereby decreasing strain across the fracture gap and promoting secondary healing.
Question 12248
Topic: 2. Trauma
Which of the following recombinant human bone morphogenetic proteins (rhBMPs) is currently FDA-approved for use as an alternative to autogenous bone graft in the treatment of acute, open tibial shaft fractures treated with an intramedullary nail?
Correct Answer & Explanation
. rhBMP-2
Explanation
Recombinant human BMP-2 (rhBMP-2) is FDA-approved for use in acute open tibial shaft fractures stabilized with an IM nail. It is also approved for anterior lumbar interbody fusions (ALIF).
Question 12249
Topic: 2. Trauma
A 32-year-old male sustains a high-energy anterior-posterior compression (APC-III) pelvic ring injury after a motor vehicle collision. He is hemodynamically unstable despite initial fluid resuscitation. Which of the following interventions should be prioritized after initial resuscitation and external pelvic stabilization?
Correct Answer & Explanation
. Angiographic embolization of bleeding pelvic vessels.
Explanation
In a hemodynamically unstable patient with a high-energy APC-III pelvic fracture that remains unstable despite initial resuscitation and external pelvic stabilization (e.g., sheet, binder), persistent hemorrhage is often due to arterial bleeding from the internal iliac artery system. Angiographic embolization is the gold standard for controlling arterial hemorrhage in this setting. While external fixators provide definitive mechanical stabilization, they do not directly control arterial bleeding. Laparotomy is for intra-abdominal bleeding (typically venous, less common in APC-III causing massive instability) or bowel injury. Urethral injury assessment can be performed but is secondary to life-threatening hemorrhage control.
Question 12250
Topic: 2. Trauma
What is the most common anatomical source of hemorrhage in a hemodynamically unstable patient with an anterior-posterior compression (APC) pelvic ring injury?
Correct Answer & Explanation
. Presacral venous plexus
Explanation
Venous bleeding accounts for up to 80% of hemorrhage in pelvic fractures, primarily from the presacral venous plexus. Arterial bleeding is less common but often involves the superior gluteal artery in lateral compression injuries or the internal pudendal in APC injuries.
Question 12251
Topic: 2. Trauma
A 32-year-old male sustains a closed tibial shaft fracture. Twelve hours later, he develops severe pain out of proportion to the injury. His diastolic blood pressure is 80 mmHg. What is the absolute intracompartmental pressure threshold and delta pressure typically indicating the need for emergent four-compartment fasciotomy?
Compartment syndrome is a clinical diagnosis, but tissue perfusion is compromised when intracompartmental pressures exceed 30 mmHg or when the delta pressure (diastolic BP minus compartment pressure) falls below 30 mmHg. Emergent fasciotomy is the definitive treatment.
Question 12252
Topic: Pelvic & Acetabular Trauma
A 45-year-old male is brought to the trauma bay after a motorcycle crash. He is tachycardic and hypotensive. Pelvic X-ray reveals a 4 cm widening of the pubic symphysis with disruption of the sacroiliac joints bilaterally. A pelvic binder is to be applied. What is the correct anatomical landmark for the placement of the pelvic binder to optimize reduction?
Correct Answer & Explanation
. Greater trochanters
Explanation
A pelvic binder should be centered over the greater trochanters to effectively close the pelvic ring volume in "open book" (APC-type) injuries. Placing the binder over the iliac crests is ineffective and can paradoxically widen the pelvis or compromise abdominal assessment.
Question 12253
Topic: 2. Trauma
A 35-year-old male presents with chronic wrist pain after a fall on an outstretched hand two years ago. Radiographs reveal a scaphoid waist fracture nonunion with sclerosis. MRI shows no gadolinium enhancement in the proximal pole. What does this MRI finding indicate?
Correct Answer & Explanation
. Avascular necrosis of the proximal pole
Explanation
The lack of gadolinium contrast enhancement in the proximal pole of the scaphoid on MRI is highly indicative of avascular necrosis (AVN). This finding significantly alters the surgical management, often necessitating a vascularized bone graft.
Question 12254
Topic: 2. Trauma
A 30-year-old male is brought to the trauma bay intubated after a motorcycle crash. He has a severely comminuted closed tibia fracture. Which of the following intracompartmental pressure measurements is the most reliable indicator for emergent fasciotomy?
Correct Answer & Explanation
. Diastolic blood pressure minus compartment pressure < 30 mmHg
Explanation
The delta pressure, defined as the diastolic blood pressure minus the compartment pressure, is the most reliable indicator for compartment syndrome. A delta pressure of less than 30 mmHg is the standard threshold indicating the need for emergent fasciotomy.
Question 12255
Topic: 2. Trauma
Which of the following fracture fixation methods relies primarily on secondary bone healing through enchondral ossification?
Correct Answer & Explanation
. Intramedullary nailing of a diaphyseal femur fracture
Explanation
Intramedullary nailing allows for relative stability and micromotion at the fracture site, promoting secondary bone healing through callus formation via enchondral ossification. Absolute stability methods rely on primary intramembranous healing.
Question 12256
Topic: 2. Trauma
A 25-year-old male sustains an open tibia fracture with extensive soft tissue loss and exposed bone lacking periosteal coverage. The injury requires a free flap for coverage. What is the Gustilo-Anderson classification of this fracture?
Correct Answer & Explanation
. Type IIIB
Explanation
Gustilo-Anderson Type IIIB fractures are open fractures with extensive soft tissue damage, periosteal stripping, and bone exposure requiring a soft tissue transfer (flap) for coverage.
Question 12257
Topic: 2. Trauma
A 40-year-old construction worker falls from a height and sustains a thoracolumbar burst fracture. According to the Denis three-column classification, which structures must be disrupted to define this as a burst fracture rather than a simple compression fracture?
Correct Answer & Explanation
. Middle column
Explanation
According to the Denis classification, a burst fracture involves failure of both the anterior and middle columns under axial load. A simple compression fracture typically involves isolated failure of the anterior column.
Question 12258
Topic: 2. Trauma
A 32-year-old male sustains a closed comminuted tibial shaft fracture. Two hours later, he develops excruciating pain out of proportion to his injury and pain with passive stretch of his hallux. His blood pressure is 110/75 mmHg. What is the most reliable compartment pressure threshold indicating the need for emergent fasciotomy?
Correct Answer & Explanation
. A compartment pressure within 30 mmHg of the diastolic blood pressure
Explanation
Acute compartment syndrome is most accurately diagnosed using the Delta P threshold. A Delta P (diastolic blood pressure minus compartment pressure) of less than 30 mmHg requires emergent fasciotomy.
Question 12259
Topic: 2. Trauma
A 25-year-old male is brought to the trauma bay hemodynamically unstable following a motorcycle collision. Radiographs demonstrate an open-book pelvic fracture with a 4 cm pubic symphyseal diastasis. A pelvic circumferential compression device (binder) is applied. For maximum mechanical advantage in reducing the pelvic volume, the binder should be centered over the:
Correct Answer & Explanation
. Greater trochanters
Explanation
A pelvic binder must be applied at the level of the greater trochanters to properly close the pelvic ring and reduce retroperitoneal volume. Application over the iliac crests can inadvertently worsen the diastasis of the true pelvis.
Question 12260
Topic: 2. Trauma
A 45-year-old farmer sustains a severe open tibia fracture (Gustilo-Anderson Type IIIA) heavily contaminated with soil and manure. Standard open fracture prophylaxis includes a first-generation cephalosporin and an aminoglycoside. What specific antibiotic must be added to this patient's regimen?
Correct Answer & Explanation
. High-dose Penicillin
Explanation
Farm-related injuries or open fractures heavily contaminated with soil are at high risk for anaerobic infections, particularly Clostridium perfringens. High-dose penicillin is added to the prophylactic antibiotic regimen to provide necessary anaerobic coverage.
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