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2. Trauma MCQs

Practice Set 305 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 6081

Topic: Pelvic & Acetabular Trauma
A 45-year-old male sustained a closed pelvic ring injury in a high-speed motor vehicle collision. Examination reveals a massive, fluctuant mass over the greater trochanter with areas of overlying skin necrosis. Aspiration yields serosanguinous fluid. What is the best initial management for this lesion?
. Observation and compression wrapping
. Percutaneous aspiration and injection of a sclerosing agent
. Open debridement with excision of necrotic tissue
. Immediate internal fixation of the pelvis directly through the lesion
. Application of a negative pressure wound therapy dressing over the intact necrotic skin

Correct Answer & Explanation

. Open debridement with excision of necrotic tissue

Explanation

This is a Morel-Lavallée lesion (a closed degloving injury). When overlying skin necrosis is present, conservative measures or percutaneous drainage are inadequate and carry a high risk of deep infection. Open debridement with excision of all non-viable tissue is required, particularly before proceeding with any definitive osteosynthesis.

Question 6082

Topic: 2. Trauma

A 25-year-old motorcyclist is brought to the trauma bay after a high-speed collision. He has massive soft tissue swelling over the left shoulder, and the left upper extremity is flail and pulseless. A chest radiograph demonstrates a widely displaced clavicle fracture and significant lateral displacement of the scapula. What is the most critical immediate step in management?

. Immediate open reduction and internal fixation of the clavicle
. Urgent angiography and vascular repair
. Forequarter amputation
. Brachial plexus exploration and nerve grafting
. Application of a figure-of-eight brace

Correct Answer & Explanation

. Urgent angiography and vascular repair

Explanation

This patient has a scapulothoracic dissociation, characterized by complete disruption of the scapulothoracic articulation. It is associated with a high incidence of life-threatening subclavian or axillary artery disruption (up to 88%) and devastating brachial plexus avulsions. Immediate angiography and vascular control/repair take precedence to save the limb and patient's life.

Question 6083

Topic: 2. Trauma

A 40-year-old male sustains a proximal tibia fracture. Radiographs and CT show a fracture line exiting through the medial cortex, with separation and depression of the entire medial tibial plateau. This is classified as a Schatzker IV fracture. What is the classic mechanism of injury for this specific fracture pattern?

. High-energy varus stress combined with axial loading
. Low-energy valgus stress in an osteoporotic patient
. High-energy hyperextension injury
. Low-energy rotational twisting mechanism
. Direct anterior blow to a flexed knee

Correct Answer & Explanation

. High-energy varus stress combined with axial loading

Explanation

A Schatzker type IV fracture involves the medial tibial plateau. Because the medial plateau is structurally stronger and denser than the lateral plateau, fracturing it requires a high-energy mechanism, classically a varus stress combined with axial loading. Due to this high energy, Schatzker IV fractures are frequently associated with popliteal artery injuries, peroneal nerve damage, and knee dislocation equivalents.

Question 6084

Topic: 2. Trauma
A 30-year-old male is admitted with a highly comminuted diaphyseal tibia fracture. He develops severe, unremitting leg pain overnight. His blood pressure is 120/80 mmHg. Intracompartmental pressure monitoring of the anterior compartment reads 55 mmHg. What is his Delta P (ΔP), and is emergency fasciotomy indicated?
. Delta P is 65 mmHg; Fasciotomy is not indicated
. Delta P is 25 mmHg; Fasciotomy is indicated
. Delta P is 40 mmHg; Fasciotomy is not indicated
. Delta P is 25 mmHg; Fasciotomy is not indicated
. Delta P is 40 mmHg; Fasciotomy is indicated

Correct Answer & Explanation

. Delta P is 25 mmHg; Fasciotomy is indicated

Explanation

Delta P (ΔP) is calculated as the Diastolic Blood Pressure minus the Intracompartmental Pressure. In this case, ΔP = 80 mmHg - 55 mmHg = 25 mmHg. A Delta P of less than 30 mmHg (threshold for adequate tissue perfusion) confirms the diagnosis of acute compartment syndrome and is an absolute indication for emergency four-compartment fasciotomy.

Question 6085

Topic: 2. Trauma

A 35-year-old male is involved in a lateral impact motor vehicle collision. Pelvic radiographs demonstrate a lateral compression (LC) type II injury pattern with a 'crescent fracture' of the posterior ilium. The sacroiliac (SI) joint is disrupted anteriorly, but the posterior iliac fragment remains anchored to the sacrum. Which of the following ligaments is primarily responsible for maintaining this posterior attachment?

. Sacrotuberous ligament
. Sacrospinous ligament
. Anterior sacroiliac ligament
. Posterior sacroiliac ligament
. Iliolumbar ligament

Correct Answer & Explanation

. Posterior sacroiliac ligament

Explanation

In a lateral compression injury resulting in a crescent fracture of the ilium (Day classification), the anterior SI ligaments typically fail, but the strong posterior sacroiliac ligaments remain intact. The posterior SI ligament complex anchors the crescentic posterior iliac fragment to the sacrum. The fracture line predictably exits through the ilium, leaving the posterior SI joint intact.

Question 6086

Topic: Upper Extremity Trauma

Historically, the arcuate artery (ascending branch of the anterior humeral circumflex artery) was considered the primary blood supply to the humeral head. However, recent quantitative cadaveric and MRI studies have demonstrated that the principal arterial supply to the humeral head actually arises from which of the following?

. Anterior humeral circumflex artery
. Posterior humeral circumflex artery
. Thoracoacromial artery
. Subscapular artery
. Profunda brachii artery

Correct Answer & Explanation

. Posterior humeral circumflex artery

Explanation

Recent anatomic and MRI studies (e.g., Hettrich et al.) have redefined the vascular anatomy of the proximal humerus, demonstrating that the posterior humeral circumflex artery (PHCA) provides approximately 64% of the blood supply to the humeral head. This paradigm shift highlights the importance of the PHCA, though preserving both vessels when possible during proximal humerus surgery remains ideal.

Question 6087

Topic: 2. Trauma

In the setting of a classic 'terrible triad' injury of the elbow (elbow dislocation, radial head fracture, and coronoid fracture), which of the following fracture patterns is most characteristic of the coronoid process injury?

. Transverse fracture of the coronoid tip
. Fracture of the anteromedial facet
. Fracture involving the sublime tubercle
. Comminuted fracture of the coronoid base
. Vertical split fracture of the coronoid

Correct Answer & Explanation

. Transverse fracture of the coronoid tip

Explanation

The typical coronoid fracture in a 'terrible triad' injury is a transverse fracture involving the tip of the coronoid (Regan-Morrey Type 1 or Type 2; O'Driscoll Tip fracture). This occurs due to the shearing force as the elbow subluxates/dislocates posterolaterally. In contrast, an anteromedial facet fracture is typical of a varus posteromedial rotatory instability (VPMRI) pattern.

Question 6088

Topic: 2. Trauma

A 28-year-old female sustains a Hawkins Type II talar neck fracture and undergoes open reduction and internal fixation. At the 8-week follow-up, an AP radiograph of the ankle reveals a subchondral radiolucent band extending across the dome of the talus (Hawkins sign). This radiographic finding indicates which of the following?

. Impending avascular necrosis of the talar body
. Nonunion of the talar neck fracture
. Resorption of subchondral bone due to intact vascular supply
. Post-traumatic arthritis of the tibiotalar joint
. Infection of the talar dome

Correct Answer & Explanation

. Resorption of subchondral bone due to intact vascular supply

Explanation

The Hawkins sign is a subchondral radiolucent band seen in the dome of the talus 6 to 8 weeks following a talar neck fracture. It represents subchondral osteopenia (bone resorption) secondary to disuse atrophy. For this resorption to occur, the talar body must have an intact vascular supply. Therefore, a positive Hawkins sign is a highly reliable indicator that avascular necrosis (AVN) of the talar body will NOT occur.

Question 6089

Topic: 2. Trauma

During an anterior intrapelvic (modified Stoppa) approach for a localized anterior column acetabular fracture, significant hemorrhage occurs while dissecting over the superior pubic ramus. This bleeding is most likely originating from an anastomosis between which two vascular networks?

. External iliac artery and internal pudendal artery
. Internal iliac artery and superior gluteal artery
. Obturator artery and inferior epigastric artery
. Superior vesical artery and obturator artery
. Femoral artery and medial circumflex femoral artery

Correct Answer & Explanation

. External iliac artery and internal pudendal artery

Explanation

The corona mortis ('crown of death') is a vascular anastomosis between the external iliac system (usually the inferior epigastric artery or vein) and the internal iliac system (obturator artery or vein). It is located over the posterior aspect of the superior pubic ramus, roughly 5-7 cm from the pubic symphysis, and is at high risk of iatrogenic injury during anterior intrapelvic approaches.

Question 6090

Topic: 2. Trauma

A 28-year-old man is admitted with a comminuted midshaft tibial fracture. Overnight, he complains of worsening leg pain out of proportion to his injury and increased pain with passive toe stretch. His blood pressure is 110/70 mmHg. Intracompartmental pressure monitoring of the anterior compartment reveals a pressure of 45 mmHg. What is his delta pressure, and what is the standard recommended management?

. Delta pressure is 65 mmHg; continue observation
. Delta pressure is 25 mmHg; proceed with emergent four-compartment fasciotomy
. Delta pressure is 45 mmHg; proceed with emergent four-compartment fasciotomy
. Delta pressure is 25 mmHg; elevate the leg above heart level and reassess in 2 hours
. Delta pressure is 65 mmHg; proceed with emergent four-compartment fasciotomy

Correct Answer & Explanation

. Delta pressure is 25 mmHg; proceed with emergent four-compartment fasciotomy

Explanation

Delta pressure is calculated as the Diastolic Blood Pressure minus the Intracompartmental Pressure (Delta P = DBP - ICP). In this patient, DBP is 70 mmHg and ICP is 45 mmHg, giving a Delta P of 25 mmHg. A Delta pressure of less than 30 mmHg, combined with strong clinical signs, is an absolute indication for an emergent four-compartment fasciotomy to treat acute compartment syndrome.

Question 6091

Topic: 2. Trauma

A 35-year-old male sustains a closed tibial shaft fracture. Two hours post-admission, he complains of severe leg pain out of proportion to the injury, unrelieved by opioids. His blood pressure is 110/70 mmHg. What intracompartmental pressure reading would mandate immediate fasciotomy?

. Absolute pressure of 20 mmHg
. Absolute pressure of 25 mmHg
. Compartment pressure within 40 mmHg of systolic blood pressure
. Compartment pressure within 30 mmHg of diastolic blood pressure
. Compartment pressure within 10 mmHg of mean arterial pressure

Correct Answer & Explanation

. Compartment pressure within 30 mmHg of diastolic blood pressure

Explanation

The diagnosis of acute compartment syndrome is supported by a Delta P (Diastolic Blood Pressure minus Compartment Pressure) of 30 mmHg or less. Therefore, a compartment pressure within 30 mmHg of the diastolic blood pressure is indicative of compartment syndrome and an absolute indication for fasciotomy. Absolute pressures (e.g., >30 mmHg) are less reliable due to variations in systemic perfusion pressure.

Question 6092

Topic: 2. Trauma
A 28-year-old male sustains a vertically oriented, highly displaced femoral neck fracture (Pauwels type III). What is the preferred fixation strategy to maximize biomechanical stability and minimize the risk of varus collapse?
. Three parallel cancellous screws placed in an inverted triangle configuration
. Two parallel cancellous screws
. Sliding hip screw with an anti-rotation screw
. Cephalomedullary nail
. Proximal femoral locking plate

Correct Answer & Explanation

. Sliding hip screw with an anti-rotation screw

Explanation

Pauwels type III fractures have a high vertical angle, subjecting the fracture to high shear forces. Biomechanical studies have shown that a fixed-angle device, such as a sliding hip screw (often supplemented with a derotational screw), provides superior resistance to varus collapse and shear compared to multiple parallel cancellous screws.

Question 6093

Topic: 2. Trauma

Recombinant human Bone Morphogenetic Protein-2 (rhBMP-2) is FDA-approved for which of the following specific orthopedic applications?

. Acute closed tibial shaft fractures
. Single-level Anterior Lumbar Interbody Fusion (ALIF)
. Posterolateral lumbar spinal fusion
. Clavicle nonunions
. Spinal fusions in skeletally immature patients

Correct Answer & Explanation

. Single-level Anterior Lumbar Interbody Fusion (ALIF)

Explanation

rhBMP-2 (Infuse) is FDA-approved for single-level Anterior Lumbar Interbody Fusion (ALIF) from L4-S1 within an LT-CAGE, as well as for acute open tibial shaft fractures stabilized with an IM nail within 14 days of injury. It is not approved for closed tibial fractures, pediatric use, or general posterolateral fusion without a specific off-label justification.

Question 6094

Topic: Pelvic & Acetabular Trauma
In the emergency management of a hemodynamically unstable patient with an open-book pelvic ring injury (APC-II or III), a circumferential pelvic sheet or binder must be applied. For optimal biomechanical reduction of the symphysis, the binder should be centered precisely over which anatomical landmark?
. Iliac crests
. Anterior superior iliac spines (ASIS)
. Greater trochanters
. Pubic symphysis
. Subtrochanteric femur

Correct Answer & Explanation

. Greater trochanters

Explanation

Pelvic binders must be centered over the greater trochanters to effectively close the pelvic ring and reduce the pubic symphysis. Placing the binder too high (over the iliac crests) can paradoxically widen the true pelvis by pushing the iliac wings inward at the top, acting as a fulcrum.

Question 6095

Topic: 2. Trauma

A 35-year-old trauma patient has a pelvic ring injury classified as a Day Type 1 crescent fracture (Young-Burgess LC-2). Which of the following best describes the optimal surgical approach and fixation for this specific fracture pattern?

. Posterior approach with tension band wiring of the SI joint
. Closed reduction and percutaneous iliosacral screw fixation
. Anterior external fixation only
. Anterior approach with plate fixation of the iliac wing
. Lumbo-pelvic fixation

Correct Answer & Explanation

. Anterior approach with plate fixation of the iliac wing

Explanation

The Day classification describes lateral compression type II (crescent) fractures. Type 1 represents a large crescent fragment where the fracture exits anterior to the SI joint, leaving the SI joint predominantly intact. The optimal fixation for this large iliac wing fragment is an anterior approach with open reduction and internal fixation (ORIF) using plates and screws. Type 2 exits into the SI joint, and Type 3 is a small crescent exiting posterior to the joint (best treated with posterior iliosacral screws).

Question 6096

Topic: Pelvic & Acetabular Trauma
According to the Resnick criteria for diagnosing Diffuse Idiopathic Skeletal Hyperostosis (DISH), all of the following are required except:
. Flowing ossification along the anterolateral aspect of at least four contiguous vertebral bodies
. Relative preservation of intervertebral disc height in the involved segments
. Absence of facet joint ankylosis
. Absence of sacroiliac joint erosion or fusion
. Presence of HLA-B27 antigen

Correct Answer & Explanation

. Presence of HLA-B27 antigen

Explanation

DISH is diagnosed radiographically using the Resnick criteria: 1) Flowing ossification over at least 4 contiguous vertebral bodies, 2) Preservation of disc space height without signs of degenerative disc disease, and 3) Absence of apophyseal joint ankylosis and sacroiliac joint erosion/sclerosis. Unlike Ankylosing Spondylitis, DISH is not strongly associated with the HLA-B27 antigen.

Question 6097

Topic: 2. Trauma
A 30-year-old man sustains a Pauwels Type III (vertical) femoral neck fracture. Biomechanically, which of the following forces primarily contributes to the high rate of failure and non-union in this fracture pattern?
. Shear forces across the fracture site
. Compressive forces across the fracture site
. Rotational forces around the femoral neck axis
. Distraction forces from the abductor musculature
. Bending forces along the femoral shaft

Correct Answer & Explanation

. Shear forces across the fracture site

Explanation

Pauwels Type III femoral neck fractures have an orientation >50 degrees from the horizontal. Biomechanically, this highly vertical orientation converts physiological weight-bearing loads into large shear forces across the fracture site. Shear forces disrupt the delicate healing process, leading to high rates of non-union and fixation failure, unlike compressive forces which generally promote bone healing.

Question 6098

Topic: 2. Trauma

A 42-year-old male sustains a high-energy Schatzker Type IV tibial plateau fracture. Imaging demonstrates a coronally oriented posteromedial fracture fragment. What is the optimal surgical approach and internal fixation strategy for this specific fragment?

. Anterolateral approach with lateral locking plate
. Posteromedial approach with an anti-glide buttress plate
. Medial approach with cancellous lag screws only
. Anterior midline approach with dual plate fixation
. Arthroscopic-assisted percutaneous screw fixation

Correct Answer & Explanation

. Posteromedial approach with an anti-glide buttress plate

Explanation

Schatzker Type IV (medial plateau) fractures often result from high-energy trauma. The classic variant involves a coronally oriented posteromedial fragment. To effectively resist the sheer forces during knee flexion, this fragment must be buttressed from behind. The optimal technique is a posteromedial approach with the application of an anti-glide or buttress plate to the posterior aspect of the medial tibial condyle.

Question 6099

Topic: 2. Trauma

Which of the following mechanical and biological conditions is absolutely required to promote primary (direct) bone healing without callus formation?

. Intramedullary reaming with nail insertion
. Controlled micromotion at the fracture site
. Absolute stability with interfragmentary compression
. Presence of a fracture gap greater than 2 mm
. Endochondral ossification pathways

Correct Answer & Explanation

. Absolute stability with interfragmentary compression

Explanation

Primary (direct) bone healing occurs via cutting cones and requires absolute stability (no motion) and direct contact between fracture fragments, typically achieved through interfragmentary compression. Secondary bone healing involves callus formation (endochondral ossification) and is promoted by relative stability and controlled micromotion.

Question 6100

Topic: 2. Trauma
A 25-year-old male sustains a vertically oriented, displaced intracapsular femoral neck fracture (Pauwels type III). What is the preferred method of internal fixation to best counteract the high vertical shear forces inherent to this fracture pattern?
. Three parallel cancellous lag screws in an inverted triangle
. A sliding hip screw (DHS) with an anti-rotation screw
. A standard cephalomedullary nail
. Two partially threaded cancellous screws placed divergently
. Cementless bipolar hemiarthroplasty

Correct Answer & Explanation

. A sliding hip screw (DHS) with an anti-rotation screw

Explanation

Pauwels type III fractures are highly vertical and subject to significant shear forces, predisposing to nonunion and varus collapse. Biomechanical studies demonstrate that a fixed-angle device, such as a sliding hip screw (dynamic hip screw) supplemented with a derotation screw, provides superior resistance to vertical shear compared to multiple cancellous screws.

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