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 5701
Topic: 2. Trauma
During the open reduction and internal fixation of a 3-part proximal humerus fracture via a standard deltopectoral approach, preservation of the primary blood supply to the humeral head is a critical consideration. According to modern anatomical perfusion studies (e.g., Hettrich, Brooks), which vessel provides the vast majority of the blood supply to the humeral head?
Correct Answer & Explanation
. Posterior humeral circumflex artery
Explanation
Historically, the anterior humeral circumflex artery (specifically the arcuate artery of Laing) was thought to be the primary blood supply to the humeral head. However, modern cadaveric studies using gadolinium enhancement (Hettrich, JBJS 2010) definitively demonstrated that the posterior humeral circumflex artery provides 64% of the blood supply to the humeral head, making it the most significant contributor.
Question 5702
Topic: 2. Trauma
A 28-year-old man sustains a talar neck fracture following a motor vehicle collision. Six weeks postoperatively, a plain radiograph reveals a subchondral radiolucent band in the dome of the talus (Hawkins sign).
What does this radiographic finding indicate?
Correct Answer & Explanation
. Intact vascular supply to the talar body.
Explanation
A Hawkins sign is a subchondral radiolucent band seen in the dome of the talus on an AP or mortise radiograph 6 to 8 weeks after a talar neck fracture. It represents subchondral osteopenia secondary to disuse. Because osteopenia requires an active blood supply to resorb bone, its presence is a highly reliable indicator that the talar body retains an intact vascular supply, ruling out avascular necrosis.
Question 5703
Topic: Pelvic & Acetabular Trauma
In the surgical management of developmental dysplasia of the hip (DDH), various pelvic osteotomies can be utilized to improve coverage.
Which of the following best describes the biomechanical principle of a Pemberton osteotomy?
Correct Answer & Explanation
. It is an incomplete osteotomy hinging at the triradiate cartilage that decreases the volume of the acetabulum.
Explanation
A Pemberton osteotomy is an incomplete trans-iliac osteotomy that hinges on the flexible, open triradiate cartilage (the ilioischial and iliopubic limbs). Because it hinges at the triradiate cartilage and folds down the acetabular roof, it inherently decreases the overall volume of the acetabulum. In contrast, the Salter innominate osteotomy is a complete cut through the ilium hinging at the pubic symphysis, altering the direction but not the volume of the acetabulum.
Question 5704
Topic: 2. Trauma
A 25-year-old male sustains a Pauwels type III (vertical) femoral neck fracture. Biomechanically, what is the primary mode of failure for this specific fracture pattern if treated inadequately with three parallel cancellous lag screws?
Correct Answer & Explanation
. Varus collapse and inferior shear displacement.
Explanation
Pauwels type III fractures have a highly vertical fracture line (>50 degrees from horizontal). This steep angle converts the normal compressive forces across the hip joint into high shear forces. The typical failure mode in a vertically oriented femoral neck fracture is varus collapse with inferior translation (shear) of the head fragment relative to the neck. Fixed-angle constructs (like a sliding hip screw or locking plate) are often favored over standard parallel screws to better resist these shear forces.
Question 5705
Topic: Pelvic & Acetabular Trauma
A 25-year-old male is brought to the trauma bay after a motorcycle accident. He has an open-book pelvic ring injury with hemodynamic instability. To effectively close the pelvic volume, a circumferential pelvic sheet or binder should be placed at the level of the:
Correct Answer & Explanation
. Greater trochanters
Explanation
A pelvic binder must be placed centered over the greater trochanters to effectively provide compression across the pelvic ring and reduce pelvic volume. Placement over the iliac crests is incorrect and can exacerbate the deformity or cause inadequate compression.
Question 5706
Topic: 2. Trauma
A 28-year-old painter accidentally discharges a high-pressure paint gun against the volar tip of his index finger. He presents 2 hours later with a small puncture wound, mild swelling, minimal pain, and intact capillary refill. What is the most appropriate management?
Correct Answer & Explanation
. Immediate wide surgical debridement of the digit
Explanation
High-pressure injection injuries are surgical emergencies, especially with organic solvents like paint or grease, due to their intense chemical toxicity and risk of compartment syndrome. Despite a benign initial presentation, they require immediate wide surgical debridement in the operating room.
Question 5707
Topic: 2. Trauma
Which of the following is considered an absolute indication for operative fixation of an acute midshaft clavicle fracture?
Correct Answer & Explanation
. Skin tenting with impending necrosis
Explanation
Absolute indications for open reduction and internal fixation of a clavicle fracture include open fractures, associated neurovascular injury, and severe skin tenting with impending necrosis. Shortening, displacement, and comminution are relative indications.
Question 5708
Topic: 2. Trauma
A 32-year-old female presents with a distal femur fracture following an MVC. CT reveals a coronal plane fracture of the lateral femoral condyle. What is the optimal surgical approach and standard fixation strategy for this specific fragment?
Correct Answer & Explanation
. Lateral approach, anterior-to-posterior lag screws.
Explanation
A Hoffa fracture (coronal shear fracture) most commonly involves the lateral femoral condyle. The optimal approach is typically a direct lateral or Swashbuckler approach. While biomechanical studies have shown that posterior-to-anterior screws may be stiffer, anterior-to-posterior (A-P) directed lag screws placed perpendicular to the fracture line are the standard and most commonly used clinical fixation method due to ease of surgical access and avoidance of posterior neurovascular structures.
Question 5709
Topic: 2. Trauma
Which of the following Bone Morphogenetic Proteins (BMPs) is NOT correctly paired with its clinical application, carrier, or mechanism?
Correct Answer & Explanation
. rhBMP-7 : FDA approved for acute, open tibial shaft fractures.
Explanation
rhBMP-2 (Infuse) is approved for use in acute, open tibial shaft fractures treated with an IM nail (using an absorbable collagen sponge carrier). rhBMP-7 (OP-1) was previously available under a humanitarian device exemption for recalcitrant tibial nonunions and revision posterolateral lumbar fusion, but it was not approved for acute open tibial fractures. Both BMPs act through serine/threonine kinase receptors and the SMAD intracellular signaling pathway.
Question 5710
Topic: 2. Trauma
A 45-year-old female is struck by a motor vehicle and sustains an anteroposterior compression (APC) type III pelvic ring injury. She remains hemodynamically unstable despite a pelvic binder and initial fluid resuscitation. What is the most appropriate next step in management?
Correct Answer & Explanation
. Pre-peritoneal pelvic packing and/or angiography for embolization.
Explanation
In a hemodynamically unstable patient with an APC pelvic ring injury who does not respond to initial mechanical stabilization (e.g., pelvic binder) and resuscitation, the source of bleeding is most likely the retroperitoneal venous plexus or arterial injury. Pre-peritoneal pelvic packing (PPP) and/or pelvic angiography with embolization are the appropriate next steps to control hemorrhage. Laparotomy is indicated for intra-abdominal bleeding, not primarily for pelvic retroperitoneal bleeding.
Question 5711
Topic: 2. Trauma
A 28-year-old male sustains a closed comminuted tibial shaft fracture. He develops severe pain out of proportion to his injury and pain with passive stretch of his hallux. Compartment pressure monitoring is obtained. Which of the following criteria is the most reliable threshold for diagnosing acute compartment syndrome and indicating the need for fasciotomy?
Correct Answer & Explanation
. Diastolic blood pressure minus compartment pressure < 30 mmHg.
Explanation
The Delta P (Diastolic blood pressure minus compartment pressure) is the most reliable objective metric for diagnosing acute compartment syndrome. A Delta P of less than 30 mmHg indicates inadequate perfusion pressure to the muscular compartments and is a clear indication for fasciotomy. Absolute compartment pressures can lead to overdiagnosis and unnecessary fasciotomies, especially in hypotensive patients.
Question 5712
Topic: Pelvic & Acetabular Trauma
A 40-year-old male is brought to the trauma bay following a crush injury. He is hemodynamically unstable. Pelvic radiographs demonstrate an anteroposterior compression (APC) type III injury with a widely open symphysis pubis. Where is the optimal anatomical placement of a circumferential pelvic sheet or binder to reduce pelvic volume?
Correct Answer & Explanation
. Centered over the greater trochanters
Explanation
A pelvic binder must be centered over the greater trochanters to generate the appropriate force vector to close an open-book pelvic ring injury effectively. Placement over the iliac crests is incorrect and can exacerbate the deformity.
Question 5713
Topic: 2. Trauma
A 32-year-old female presents with a highly unstable, vertically oriented (Pauwels type III) femoral neck fracture following a fall from height. What is the most biomechanically advantageous construct for internal fixation of this specific fracture pattern to minimize shear forces?
Correct Answer & Explanation
. A sliding hip screw (fixed-angle device) with an anti-rotation screw
Explanation
Pauwels type III fractures are highly vertical and subjected to massive shear forces. A fixed-angle construct (like a sliding hip screw) combined with an anti-rotation screw provides superior biomechanical stability compared to parallel cancellous screws.
Question 5714
Topic: Pelvic & Acetabular Trauma
A 25-year-old male is brought to the trauma bay hemodynamically unstable following a motorcycle collision. Pelvic radiograph reveals an APC-III pelvic ring injury. Despite application of a pelvic binder and initial fluid resuscitation, he remains hypotensive. What is the most common anatomical source of hemorrhage in this specific injury pattern?
Correct Answer & Explanation
. Presacral venous plexus
Explanation
Up to 80-90% of bleeding in pelvic ring injuries originates from the low-pressure presacral venous plexus and cancellous bone edges. Arterial bleeding is less common but may require angioembolization if venous sources are controlled and the patient remains unstable.
Question 5715
Topic: Pelvic & Acetabular Trauma
A 45-year-old male is brought to the ED after a motorcycle crash. He is hypotensive with a mechanically unstable pelvis (APC type III). A pelvic binder is applied. Where is the optimal anatomical position for the pelvic binder to maximize reduction and minimize complications?
Correct Answer & Explanation
. Centered over the greater trochanters
Explanation
To effectively close the pelvic ring and control hemorrhage, a pelvic binder must be placed at the level of the greater trochanters. Placement over the iliac crests is ineffective and can paradoxically open the pelvis further in some fracture patterns.
Question 5716
Topic: 2. Trauma
A 38-year-old male sustains a high-energy Schatzker VI tibial plateau fracture. The limb is grossly swollen, and ABI is 0.8. A CT angiogram reveals an intimal tear of the popliteal artery without complete occlusion, but distal pulses are diminished. What is the correct sequence of management?
Correct Answer & Explanation
. Application of a spanning external fixator followed by vascular intervention
Explanation
In the setting of a complex intra-articular fracture with a vascular injury, bone stability must be achieved rapidly, usually with a spanning external fixator, to protect the subsequent vascular repair. Definitive ORIF is delayed until soft tissues permit.
Question 5717
Topic: Pelvic & Acetabular Trauma
A 42-year-old male is brought to the trauma bay after a motorcycle collision. He is hemodynamically unstable with a heart rate of 120 bpm and BP of 80/50 mmHg. Pelvic radiograph reveals an APC-III pelvic ring injury. A pelvic binder is applied. To maximize reduction of the symphysis pubis and control hemorrhage, at what anatomic level should the pelvic binder be centered?
Correct Answer & Explanation
. Greater trochanters
Explanation
Pelvic binders must be centered over the greater trochanters to effectively close an open-book pelvic ring injury. Placement over the iliac crests is incorrect and can cause paradoxical opening of the pelvic ring, worsening the hemorrhage.
Question 5718
Topic: 2. Trauma
A 35-year-old male sustains a high-energy pelvic injury after a motor vehicle collision, presenting with hemodynamic instability. Initial resuscitation includes two liters of crystalloid and two units of packed red blood cells. A physical exam reveals a shortened and externally rotated left lower extremity. Pelvic X-rays and CT scan demonstrate a Young-Burgess LC-III pattern injury with a symphyseal disruption, bilateral sacral fractures, and evidence of significant retroperitoneal hematoma. What is the most appropriate immediate surgical management strategy?
Correct Answer & Explanation
. Anterior external fixation followed by angiography and embolization if bleeding persists
Explanation
In a hemodynamically unstable patient with a high-energy pelvic fracture, the immediate priority is hemorrhage control. An anterior external fixator rapidly stabilizes the anterior pelvic ring, reduces pelvic volume, and indirectly tamponades venous bleeding from the retroperitoneal space. If hemodynamic instability persists despite initial anterior stabilization and fluid resuscitation, pelvic angiography with embolization is the next crucial step to identify and control arterial bleeding, which is less commonly addressed by mechanical stabilization alone. Definitive internal fixation (ORIF or percutaneous screws) is performed once the patient is hemodynamically stable. Exploratory laparotomy with pelvic packing is reserved for cases where arterial embolization fails or is unavailable, or if there's significant intra-abdominal injury.
Question 5719
Topic: 2. Trauma
A 28-year-old male sustains a vertically oriented Pauwels type III femoral neck fracture in a motorcycle collision. Which fixation construct offers the greatest biomechanical stability against shear forces for this specific fracture pattern?
Correct Answer & Explanation
. Dynamic hip screw (DHS) with an anti-rotation screw
Explanation
For vertical shear fractures (Pauwels III), a fixed-angle device like a DHS with a derotational screw provides superior biomechanical stability compared to parallel cancellous screws. It effectively converts shear forces into compressive forces, reducing the risk of varus collapse and nonunion.
Question 5720
Topic: Pelvic & Acetabular Trauma
A 35-year-old male presents with a hypotensive APC-III pelvic ring disruption following a severe crush injury. Despite initial massive transfusion protocols and appropriate application of a pelvic binder, he remains hemodynamically unstable. What is the most common anatomical source of massive hemorrhage in this specific fracture pattern?
Correct Answer & Explanation
. Presacral venous plexus
Explanation
The presacral venous plexus and disrupted cancellous bone edges are the most common sources of bleeding in severe pelvic ring injuries, accounting for up to 80-90% of bleeding volume. While arterial bleeding (e.g., superior gluteal artery) is life-threatening and treated with embolization, it is less frequent overall.
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