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2. Trauma MCQs

Practice Set 234 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 4661

Topic: 2. Trauma

During the pathophysiological development of acute compartment syndrome following a severe closed tibial shaft fracture, what is the initial microvascular event that initiates the cascade leading to muscle and nerve ischemia?

. Arteriolar spasm due to sympathetic hyper-reactivity
. Mechanical occlusion of major axial arteries
. Venous outflow obstruction due to elevated extraluminal tissue pressure
. Lymphatic outflow obstruction
. Direct mechanical disruption of the capillary endothelium

Correct Answer & Explanation

. Arteriolar spasm due to sympathetic hyper-reactivity

Explanation

Acute compartment syndrome develops when the pressure within a closed fascial space increases. The initial microvascular event is the compression of thin-walled post-capillary venules, causing venous outflow obstruction. This lack of venous egress leads to engorgement of the capillary bed, further increasing intracompartmental pressure. Once the tissue pressure exceeds the capillary perfusion pressure (which is closely tied to diastolic blood pressure), capillary flow ceases, resulting in cellular hypoxia and ischemia. Major arterial flow is typically maintained until very late in the process, which is why distal pulses are notoriously unreliable for ruling out compartment syndrome.

Question 4662

Topic: 2. Trauma
A 22-year-old farm worker sustains a severely contaminated open tibia fracture (Gustilo-Anderson IIIA) after his leg becomes trapped in a soil-tilling machine. He has no known drug allergies. According to current evidence-based guidelines and classical orthopaedic teaching, which of the following is the most appropriate prophylactic intravenous antibiotic regimen to administer upon emergency department presentation?
. First-generation cephalosporin alone
. Third-generation cephalosporin and an aminoglycoside
. First-generation cephalosporin and a fluoroquinolone
. First-generation cephalosporin, an aminoglycoside, and high-dose penicillin
. Vancomycin and piperacillin-tazobactam

Correct Answer & Explanation

. First-generation cephalosporin, an aminoglycoside, and high-dose penicillin

Explanation

For severe open fractures (Gustilo Type III), standard prophylaxis includes gram-positive coverage (first-generation cephalosporin, like cefazolin) and expanded gram-negative coverage (an aminoglycoside, like gentamicin, or alternatively a third-generation cephalosporin like ceftriaxone). However, in the setting of farm-related injuries, gross soil contamination, or potential ischemic tissue (such as high-energy crush injuries), there is a significant risk for anaerobic infection, specifically Clostridium perfringens (which causes gas gangrene). Therefore, the classic and standard board-tested recommendation is to add high-dose penicillin to the regimen to provide robust anaerobic coverage.

Question 4663

Topic: 2. Trauma

A 42-year-old male sustains a severe Schatzker VI tibial plateau fracture in a high-speed motor vehicle collision. He is intubated in the intensive care unit. Which of the following continuous compartment pressure readings definitively indicates the need for a four-compartment fasciotomy?

. Absolute compartment pressure consistently > 20 mmHg
. Delta P (Diastolic Blood Pressure - Compartment Pressure) < 30 mmHg
. Delta P (Mean Arterial Pressure - Compartment Pressure) < 30 mmHg
. Absolute compartment pressure > 30 mmHg regardless of blood pressure
. Compartment pressure equal to Systolic Blood Pressure minus 40 mmHg

Correct Answer & Explanation

. Absolute compartment pressure consistently > 20 mmHg

Explanation

The most reliable threshold for diagnosing acute compartment syndrome in a polytrauma or obtunded patient is a Delta P (Diastolic Blood Pressure minus Compartment Pressure) of less than 30 mmHg. Relying on absolute pressure alone (e.g., > 30 mmHg) can lead to unnecessary fasciotomies, especially in hypertensive patients, or missed diagnoses in hypotensive patients.

Question 4664

Topic: 2. Trauma

When using an intramedullary nail for a proximal third extra-articular tibia fracture, the fracture classically displaces into an apex anterior (procurvatum) and valgus deformity. To prevent this deformity using blocking screws (Poller screws) in the proximal segment, where should the screws be placed relative to the intended path of the intramedullary nail?

. Anterior and medial
. Anterior and lateral
. Posterior and lateral
. Posterior and medial
. Distal to the fracture site only

Correct Answer & Explanation

. Anterior and medial

Explanation

Blocking screws narrow the medullary canal and guide the path of the intramedullary nail. They should be placed on the concave side of the expected deformity. To prevent an apex anterior (procurvatum) deformity, the screw is placed posterior to the nail in the proximal fragment. To prevent a valgus (apex medial) deformity, the screw is placed lateral to the nail. Therefore, the correct placement is posterior and lateral.

Question 4665

Topic: 2. Trauma

A 45-year-old female sustains a bicondylar tibial plateau fracture with a significant, displaced posteromedial shear fragment. A posteromedial surgical approach is planned to buttress this fragment. Which intermuscular interval is utilized for the standard posteromedial approach to the tibial plateau?

. Between the pes anserinus and the medial head of the gastrocnemius
. Between the medial head of the gastrocnemius and the semimembranosus
. Between the soleus and the popliteus
. Between the vastus medialis and the sartorius
. Between the semitendinosus and semimembranosus

Correct Answer & Explanation

. Between the pes anserinus and the medial head of the gastrocnemius

Explanation

The standard posteromedial approach to the knee for tibial plateau fractures utilizes the interval between the medial head of the gastrocnemius and the semimembranosus. Retracting the medial gastrocnemius laterally protects the neurovascular bundle in the popliteal fossa.

Question 4666

Topic: 2. Trauma

A 32-year-old male undergoes open reduction and internal fixation of a transverse patella fracture utilizing a standard anterior tension band wiring construct. Biomechanically, this construct achieves stability and promotes healing by converting which of the following forces into articular compression?

. Compressive forces at the posterior cortex during knee extension
. Tensile forces at the anterior cortex during knee flexion
. Tensile forces at the anterior cortex during knee extension
. Shear forces at the articular surface during knee flexion
. Rotational forces during active quadriceps contraction

Correct Answer & Explanation

. Compressive forces at the posterior cortex during knee extension

Explanation

The tension band principle relies on placing a tension band on the convex (tension) side of a bone. For the patella, during knee flexion, the anterior cortex experiences tensile forces while the articular (posterior) surface experiences compressive forces. An anteriorly placed tension band wire resists these tensile forces and converts them into compressive forces across the articular surface, enhancing stability and healing.

Question 4667

Topic: 2. Trauma

A 25-year-old male polytrauma patient is diagnosed with a Type IIa Fraser floating knee (transverse diaphyseal femur fracture and intra-articular proximal tibia fracture). Both injuries require operative fixation. What is the generally recommended sequence of fixation to optimize alignment and knee biomechanics?

. Femoral shaft fixation followed by tibial plateau fixation
. Tibial plateau fixation followed by femoral shaft fixation
. Simultaneous intramedullary nailing of both fractures
. Temporary external fixation of both followed by delayed definitive fixation of the tibia first
. Non-operative management of the tibia and intramedullary nailing of the femur

Correct Answer & Explanation

. Femoral shaft fixation followed by tibial plateau fixation

Explanation

In a Type IIa floating knee (femoral shaft + tibial plateau), the recommended sequence is typically to fix the femoral shaft first. This provides a stable reference limb to appropriately judge alignment and length when reconstructing the articular surface of the tibial plateau, and prevents displacing a newly fixed plateau while manipulating the femur. (Note: If both were intra-articular [Type IIc], the articular surfaces must be reconstructed prior to diaphyseal components).

Question 4668

Topic: 2. Trauma

A 33-year-old male sustains an isolated coronal shear fracture of the lateral femoral condyle (Hoffa fracture). Open reduction and internal fixation is planned. Regarding interfragmentary lag screw fixation, which configuration offers the greatest biomechanical stiffness and resistance to pullout for this specific fracture pattern?

. Two anterior-to-posterior (AP) lag screws placed perpendicularly to the fracture line
. Two posterior-to-anterior (PA) lag screws placed perpendicularly to the fracture line
. A single lag screw placed directly inferior-to-superior
. A single large-fragment lag screw placed strictly laterally
. Screws placed parallel to the articular surface from medial to lateral

Correct Answer & Explanation

. Two anterior-to-posterior (AP) lag screws placed perpendicularly to the fracture line

Explanation

Biomechanical studies (e.g., Jarit et al.) have demonstrated that posterior-to-anterior (PA) lag screws provide significantly greater construct stiffness, higher load to failure, and better resistance to pullout compared to anterior-to-posterior (AP) screws for Hoffa fractures, primarily because the posterior bone is denser and offers better thread purchase.

Question 4669

Topic: 2. Trauma
A 14-year-old boy presents with a displaced tibial tubercle avulsion fracture (Ogden Type III) sustained while jumping during a basketball game. Over the next 4 hours, he complains of escalating, severe pain in his anterior leg, with pain elicited on passive plantarflexion of the toes. Which vascular structure is most commonly injured in this scenario, contributing to this sight-threatening complication?
. Popliteal artery
. Anterior tibial artery
. Anterior tibial recurrent artery
. Posterior tibial artery
. Sural artery

Correct Answer & Explanation

. Anterior tibial recurrent artery

Explanation

Tibial tubercle avulsion fractures, especially when displaced, carry a high risk of acute anterior compartment syndrome. This is frequently caused by disruption and bleeding from the anterior tibial recurrent artery, which is intimately associated with the proximal tibia and extensor mechanism near the tubercle.

Question 4670

Topic: 2. Trauma
A 12-year-old female sustains a completely displaced tibial eminence fracture (Meyers and McKeever Type III) after a skiing accident. Closed reduction under general anesthesia is attempted but is unsuccessful due to an intra-articular block to reduction. What is the most common anatomic structure blocking the reduction of this fracture?
. Anterior horn of the medial meniscus
. Anterior horn of the lateral meniscus
. Transverse intermeniscal ligament
. Fat pad impingement
. Posterior horn of the medial meniscus

Correct Answer & Explanation

. Anterior horn of the medial meniscus

Explanation

In completely displaced tibial eminence (tibial spine) fractures (Meyers and McKeever Type III), the anterior horn of the medial meniscus frequently becomes entrapped beneath the avulsed bony fragment, preventing anatomic reduction and necessitating arthroscopic or open reduction.

Question 4671

Topic: 2. Trauma
A 35-year-old male sustains a Gustilo-Anderson Type IIIB open fracture of the proximal third of the tibia with significant anterior soft tissue loss. Following aggressive serial debridements and skeletal stabilization, soft tissue coverage is required. Which of the following is the most appropriate reliable local muscle flap option for this defect?
. Soleus rotational flap
. Medial gastrocnemius rotational flap
. Reverse sural artery flap
. Anterolateral thigh (ALT) free flap
. Fasciocutaneous cross-leg flap

Correct Answer & Explanation

. Medial gastrocnemius rotational flap

Explanation

For soft tissue coverage of the lower extremity, local rotational flaps are often selected based on the zone of injury. Defects of the proximal third of the tibia are classically covered with a medial (or lateral) gastrocnemius rotational flap. The middle third typically utilizes a soleus flap, while the distal third generally requires a free tissue transfer.

Question 4672

Topic: 2. Trauma

Nine months after lateral locked plating of a comminuted distal femur fracture (AO/OTA 33-A3), a 65-year-old patient presents with new-onset thigh pain. Radiographs reveal a broken lateral plate at the fracture site, varus collapse, and a persistent medial cortical void. What biomechanical principle of locked plating was most likely violated, contributing to this fatigue failure?

. Over-contouring the locked plate to fit flush against the lateral cortex
. Failure to use a titanium implant in osteoporotic bone
. Too short of a plate working length spanning the comminuted fracture zone
. Placing screws purely in a bicortical fashion distally
. Use of compression screws inside the locking plate holes

Correct Answer & Explanation

. Over-contouring the locked plate to fit flush against the lateral cortex

Explanation

A common cause of locked plate failure in comminuted fractures with a medial void is a working length that is too short. A short working length increases the stiffness of the construct, which concentrates stress onto a short segment of the plate over the nonunion site, ultimately leading to cyclic fatigue failure and plate breakage. A longer working length allows the construct to distribute strain over a larger area.

Question 4673

Topic: 2. Trauma

Following a high-energy closed proximal tibia fracture, a patient develops acute compartment syndrome. Which of the following compartments is most frequently affected, and what physical examination finding is widely considered its most sensitive early clinical indicator?

. Anterior compartment; pain out of proportion to injury or with passive stretch
. Superficial posterior compartment; absent dorsalis pedis pulse
. Deep posterior compartment; pallor and poikilothermia of the foot
. Lateral compartment; inability to actively evert the foot
. Anterior compartment; new onset foot drop

Correct Answer & Explanation

. Anterior compartment; pain out of proportion to injury or with passive stretch

Explanation

The anterior compartment of the leg is the most commonly affected compartment in acute compartment syndrome following tibia fractures. The most sensitive and reliable early clinical indicator is pain out of proportion to the apparent injury, classically exacerbated by passive stretch of the muscles in that compartment (e.g., passive plantarflexion of the toes stretching the anterior compartment muscles). Pulselessness and paralysis (e.g., foot drop) are very late and often irreversible signs.

Question 4674

Topic: 2. Trauma

A 50-year-old male presents with a Schatzker Type IV (medial) tibial plateau fracture. Compared to a low-energy Schatzker Type II (lateral split-depression) fracture, this fracture pattern has a significantly higher association with which of the following concomitant injuries?

. Lateral meniscal tear
. Iliotibial band avulsion (Segond fracture)
. Popliteal artery injury and knee dislocation equivalent
. Medial collateral ligament (MCL) tear
. Common peroneal nerve palsy

Correct Answer & Explanation

. Lateral meniscal tear

Explanation

A Schatzker Type IV fracture involves the medial plateau and is typically a high-energy, varus-directed injury. Because the medial plateau is structurally denser than the lateral side, it requires substantial force to fracture. Consequently, Schatzker IV fractures are often considered 'knee dislocation equivalents' and carry a significantly higher risk of popliteal artery injury and disruption of the lateral soft tissue structures (LCL, posterolateral corner) compared to Schatzker II fractures.

Question 4675

Topic: 2. Trauma

A 24-year-old male presents with bilateral closed femoral shaft fractures and a pulmonary contusion following a high-speed motorcycle crash. His initial blood pressure is 90/60 mmHg, heart rate is 120 bpm, and base deficit is -8. Resuscitation improves his vitals marginally, but base deficit remains -6. According to the principles of Damage Control Orthopedics (DCO), which of the following is the most appropriate initial management for his femur fractures?

. Immediate reamed antegrade intramedullary nailing of both femurs
. Immediate unreamed intramedullary nailing of both femurs
. External fixation of both femurs with planned conversion to intramedullary nailing
. Non-operative management with skeletal traction for 6 weeks
. Immediate open reduction and internal fixation with dynamic compression plates

Correct Answer & Explanation

. Immediate reamed antegrade intramedullary nailing of both femurs

Explanation

This patient is hemodynamically 'borderline' or 'unstable' (persistent high base deficit, bilateral femur fractures, chest trauma). According to Damage Control Orthopedics (DCO) principles, early definitive care (Early Total Care - ETC) with intramedullary nailing poses an unacceptable risk of a 'second hit' (e.g., ARDS, fat embolism, multi-organ failure). Rapid temporary stabilization with external fixation limits ongoing hemorrhage and systemic inflammatory response, with planned conversion to definitive IM nailing once physiology normalizes.

Question 4676

Topic: 2. Trauma

A 32-year-old male undergoes intramedullary nailing of a proximal-third tibial shaft fracture using a standard infrapatellar approach. Which of the following malalignments is most commonly associated with this specific technique for this fracture pattern?

. Apex posterior and varus
. Apex anterior and valgus
. Apex posterior and valgus
. Apex anterior and varus
. Shortening and external rotation

Correct Answer & Explanation

. Apex posterior and varus

Explanation

Proximal third tibial fractures treated with infrapatellar intramedullary nailing commonly fall into an apex anterior (procurvatum) and valgus deformity. This is due to the pull of the patellar tendon and the medial starting point of the nail.

Question 4677

Topic: 2. Trauma

A 40-year-old female sustains a bicondylar tibial plateau fracture (Schatzker VI). CT imaging demonstrates a large, displaced posteromedial coronal split fragment. When planning surgical fixation, what is the most appropriate approach and fixation strategy for this specific fragment?

. Anterolateral approach with a laterally applied locking plate capturing the fragment
. Direct posterior approach with an anterior-to-posterior lag screw
. Posteromedial approach with an antiglide plate applied at the apex of the fracture
. Anteromedial approach with a medially applied locking plate
. Arthroscopic-assisted percutaneous screw fixation from anterior to posterior

Correct Answer & Explanation

. Anterolateral approach with a laterally applied locking plate capturing the fragment

Explanation

Displaced posteromedial coronal fragments in tibial plateau fractures are best treated with a posteromedial approach and an under-contoured antiglide plate. Laterally applied locking plates often fail to adequately capture or buttress this fragment.

Question 4678

Topic: 2. Trauma

A 35-year-old male sustains a distal femur fracture. CT imaging reveals a coronal plane fracture of the lateral femoral condyle. Which of the following describes the optimal biomechanical fixation construct for this specific fracture pattern?

. Lateral locking plate alone
. Anterior-to-posterior oriented partially threaded cancellous screws
. Posterior-to-anterior oriented lag screws with a lateral neutralization plate
. Medial to lateral fully threaded cortical screws
. Retrograde intramedullary nail

Correct Answer & Explanation

. Lateral locking plate alone

Explanation

A Hoffa fracture (coronal split of the femoral condyle) is optimally fixed with posterior-to-anterior lag screws, which provide superior biomechanical pull-out strength compared to anterior-to-posterior screws. This is typically supplemented with a lateral neutralization plate.

Question 4679

Topic: 2. Trauma

A 22-year-old male presents with bilateral femoral shaft fractures and a severe closed head injury (GCS 6) following a motor vehicle collision. His initial lactate is 4.5 mmol/L and base deficit is -8. What is the most appropriate initial management of his bilateral femur fractures?

. Bilateral reamed antegrade intramedullary nailing
. Bilateral unreamed antegrade intramedullary nailing
. Bilateral retrograde intramedullary nailing
. Bilateral temporizing external fixation
. Open reduction and internal fixation with locking plates

Correct Answer & Explanation

. Bilateral temporizing external fixation

Explanation

This patient is metabolically unstable and has a severe head injury. Under Damage Control Orthopedics (DCO) principles, temporizing external fixation prevents a "second hit" phenomenon and avoids further systemic physiologic burden.

Question 4680

Topic: 2. Trauma

A 45-year-old female sustains a highly comminuted fracture of the inferior pole of the patella. The fragments are too small for screw fixation. What is the preferred surgical management to restore the extensor mechanism?

. Total patellectomy and advancement of the quadriceps tendon
. Partial patellectomy with transosseous suture reattachment of the patellar tendon
. Figure-of-eight tension band wiring alone
. Patellofemoral arthrodesis
. Nonoperative management in a cylinder cast

Correct Answer & Explanation

. Partial patellectomy with transosseous suture reattachment of the patellar tendon

Explanation

For comminuted inferior pole patella fractures unamenable to internal fixation, partial patellectomy with direct reattachment of the patellar tendon via transosseous tunnels or suture anchors is the gold standard.

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