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2. Trauma MCQs

Practice Set 429 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 8561

Topic: 2. Trauma

A 65-year-old woman sustains a highly comminuted fracture of the olecranon that extends distally to involve the coronoid process. Which of the following internal fixation constructs is most appropriate for this specific fracture pattern?

. Tension band wiring
. Intramedullary cancellous screw alone
. Dorsal bridge plating across the radiocarpal joint
. Pre-contoured posterior locking plate
. Excision of the olecranon fragment and triceps advancement

Correct Answer & Explanation

. Pre-contoured posterior locking plate

Explanation

While tension band wiring is appropriate for simple, transverse olecranon fractures, it is strictly contraindicated in comminuted fractures or those extending to the coronoid (Monteggia variants) due to the risk of collapse and shortening. Plate fixation provides the rigid stabilization necessary for comminuted patterns.

Question 8562

Topic: 2. Trauma

An 8-year-old boy presents to the emergency department with arm pain after throwing a baseball. Radiographs show a minimally displaced pathologic fracture through a centrally located, completely lytic lesion in the proximal humerus metaphysis. A 'fallen leaf' sign is visible. What is the most appropriate initial management?

. Immediate intralesional curettage and bone grafting
. Immobilization in a sling to allow fracture healing
. Aspiration and injection of methylprednisolone
. Wide surgical resection
. Intravenous bisphosphonate therapy

Correct Answer & Explanation

. Immobilization in a sling to allow fracture healing

Explanation

The clinical scenario and 'fallen leaf' sign are diagnostic of a unicameral (simple) bone cyst (UBC). When a patient presents with a pathologic fracture through a UBC in the upper extremity, initial management is non-operative (e.g., sling immobilization) to allow the fracture to heal. Surgical intervention or injections are typically reserved for persistent cysts after fracture healing or lesions with a high risk of recurrent fracture.

Question 8563

Topic: 2. Trauma

An 8-year-old boy sustains a pathologic fracture of the proximal humerus after a minor fall. Radiographs show a centrally located, completely lytic lesion in the metadiaphysis with a 'fallen leaf' sign. What is the most appropriate initial management for this presentation?

. Open reduction and internal fixation with a locked plate
. Intralesional curettage and bone grafting
. Immobilization in a sling and swathe
. En bloc resection and allograft reconstruction
. Percutaneous injection of bone marrow aspirate

Correct Answer & Explanation

. Immobilization in a sling and swathe

Explanation

The presence of a centrally located lytic lesion with a 'fallen leaf' sign (a cortical fragment that falls to the dependent portion of a fluid-filled cyst) in a child is pathognomonic for a unicameral bone cyst (UBC). When a UBC presents with a pathologic fracture, the initial treatment is nonoperative immobilization (sling and swathe) to allow the fracture to heal. Fracture healing can sometimes lead to spontaneous resolution of the cyst.

Question 8564

Topic: 2. Trauma

A 45-year-old patient who smokes 1 pack per day sustained a closed tibial shaft fracture that was treated with intramedullary nailing. Six months postoperatively, radiographs demonstrate a hypertrophic nonunion with abundant callus formation but no bridging bone. What is the most appropriate next step in management?

. Application of recombinant bone morphogenetic protein (rhBMP)
. Exchange intramedullary nailing to a larger diameter nail
. Pulsed electromagnetic field therapy
. Open debridement and autologous iliac crest bone grafting
. Platelet-rich plasma (PRP) injection into the fracture site

Correct Answer & Explanation

. Exchange intramedullary nailing to a larger diameter nail

Explanation

Hypertrophic nonunions are characterized by abundant callus formation (elephant's foot) without bridging bone. This occurs due to inadequate mechanical stability, not a lack of biology (as seen in atrophic nonunions). The biological potential for healing is intact. Therefore, treatment focuses on increasing mechanical stability. In the setting of a previously nailed tibial shaft, this is most effectively achieved with exchange intramedullary nailing to a larger diameter nail, which increases biomechanical stability and allows the biologically active fracture to heal.

Question 8565

Topic: 2. Trauma

A 45-year-old man requires a unilateral uniplanar external fixator for an open tibial shaft fracture. You are selecting half-pins for the construct. According to biomechanical principles, increasing the core diameter of the half-pin by a factor of two will increase its bending stiffness by what factor?

. 2
. 4
. 8
. 16
. 32

Correct Answer & Explanation

. 16

Explanation

The bending stiffness of a solid cylinder, such as a half-pin or a screw, is proportional to the area moment of inertia, which is proportional to the radius (or diameter) to the fourth power (r^4). Therefore, doubling the core diameter increases the bending stiffness by a factor of 2^4 = 16. This is a crucial concept in external and internal fixation, as the core diameter of the pin/screw is the most significant geometric factor in determining its resistance to bending forces.

Question 8566

Topic: 2. Trauma

The use of the reamer-irrigator-aspirator (RIA) system for autologous bone graft harvesting from the femoral canal is most associated with which of the following advantages when compared to traditional iliac crest bone grafting (ICBG)?

. Higher concentration of structural cortical strut graft
. Lower volume of harvestable graft material
. Increased mechanical support properties of the resulting graft
. Decreased donor site morbidity with equivalent or greater osteogenic precursor cell yield
. Complete elimination of heterotopic ossification risk at the donor site

Correct Answer & Explanation

. Decreased donor site morbidity with equivalent or greater osteogenic precursor cell yield

Explanation

The RIA system was developed to manage intramedullary canal pressures during reaming but has become a valuable tool for bone graft harvest. Its primary advantage over ICBG is a massive reduction in donor site morbidity (pain, nerve injury, infection) while yielding large volumes (often 40-80 cc) of bone graft. The RIA effluent contains high concentrations of mesenchymal stem cells (MSCs) and growth factors comparable to or exceeding those found in ICBG, though it does not provide structural mechanical support.

Question 8567

Topic: 2. Trauma

Following a closed distal humerus fracture, a patient demonstrates complete radial nerve palsy. A nerve conduction study performed at 4 weeks shows absent distal motor responses and the presence of fibrillation potentials on electromyography (EMG). Assuming the nerve trunk is macroscopically intact, this injury is best classified as which of the following?

. Neuropraxia
. Axonotmesis
. Neurotmesis
. Sunderland Grade V
. Sunderland Grade I

Correct Answer & Explanation

. Axonotmesis

Explanation

The presence of fibrillation potentials on EMG indicates denervation, meaning axonal disruption has occurred with subsequent Wallerian degeneration. Because the nerve trunk is macroscopically intact, the injury is not a neurotmesis (Sunderland V), which involves complete transection of the nerve. Axonotmesis (Seddon) involves loss of axonal continuity with intact endoneurium (Sunderland II), perineurium, or epineurium, leading to Wallerian degeneration distal to the injury, but with the potential for regeneration. Neuropraxia (Sunderland I) involves focal demyelination without axonal disruption, maintaining distal excitability without fibrillation potentials.

Question 8568

Topic: 2. Trauma

When inserting a fully threaded cortical screw across a fracture to achieve rigid internal fixation without the use of a plate, which of the following represents the primary mechanism by which a screw generates interfragmentary compression (lag technique)?

. The shear stress generated at the screw-bone interface
. The tensile force created in the screw core as it is tightened against the near cortex
. The bending moment applied to the screw head
. The pull-out strength of the far cortex alone
. The frictional force between the screw head and the screwdriver

Correct Answer & Explanation

. The tensile force created in the screw core as it is tightened against the near cortex

Explanation

A screw acting as a lag screw generates compression by transforming torque (rotational force applied during tightening) into a tensile force along the core of the screw. Because the near cortex is over-drilled (gliding hole), the threads only engage the far cortex. As the screw head engages the near cortex, further tightening places the screw core under tension, drawing the far fragment toward the near fragment and compressing the fracture.

Question 8569

Topic: 2. Trauma

You are assisting in the design of a new cancellous screw for metaphyseal fracture fixation. Which of the following modifications to the screw design will most significantly increase its pullout strength?

. Increasing the core diameter
. Increasing the pitch
. Increasing the outer (thread) diameter
. Decreasing the length of engagement
. Decreasing the thread depth

Correct Answer & Explanation

. Increasing the outer (thread) diameter

Explanation

Screw pullout strength is directly proportional to the outer (thread) diameter, the length of thread engagement, and the shear strength of the surrounding bone. Increasing the outer diameter increases pullout strength. Increasing the core diameter improves the bending strength of the screw but decreases thread depth (if outer diameter is constant), thereby decreasing pullout strength. Increasing the pitch (fewer threads per unit length) decreases pullout strength.

Question 8570

Topic: 2. Trauma

The Segond fracture is a pathognomonic sign of an anterior cruciate ligament (ACL) tear. This avulsion fracture from the anterolateral proximal tibia involves the insertion of which capsuloligamentous structure?

. Iliotibial band
. Biceps femoris
. Anterolateral ligament (ALL)
. Lateral collateral ligament (LCL)
. Popliteofibular ligament

Correct Answer & Explanation

. Anterolateral ligament (ALL)

Explanation

The Segond fracture is a bony avulsion of the anterolateral ligament (ALL) and the meniscotibial attachment of the lateral capsule from the proximal anterolateral tibia. It is highly correlated with ACL ruptures.

Question 8571

Topic: Upper Extremity Trauma

During an anatomic reconstruction of the coracoclavicular (CC) ligaments for an acromioclavicular joint separation, the surgeon must replicate the natural orientation of the conoid and trapezoid ligaments. What is the spatial relationship of the conoid ligament relative to the trapezoid ligament?

. Anteromedial
. Anterolateral
. Posteromedial
. Posterolateral
. Directly inferior

Correct Answer & Explanation

. Posteromedial

Explanation

The coracoclavicular ligaments consist of the conoid and trapezoid. The conoid ligament is positioned posteromedial to the trapezoid ligament and provides the primary restraint to superior clavicular translation.

Question 8572

Topic: Upper Extremity Trauma

In the setting of an Essex-Lopresti injury, longitudinal stability of the forearm is compromised due to a radial head fracture and disruption of the interosseous membrane (IOM). Which anatomical component of the IOM provides the greatest resistance to proximal migration of the radius?

. Distal oblique bundle
. Proximal oblique cord
. Dorsal oblique accessory cord
. Central band
. Volar radioulnar ligament

Correct Answer & Explanation

. Central band

Explanation

The central band is the thickest and most biomechanically robust component of the interosseous membrane. It originates on the radius and inserts distally on the ulna (running in a distal-ulnarward direction), acting as the primary soft-tissue restraint to longitudinal radioulnar translation.

Question 8573

Topic: 2. Trauma

During minimally invasive plate osteosynthesis (MIPO) for a distal third fibular fracture, the superficial peroneal nerve (SPN) is at risk during percutaneous screw placement. On average, the SPN pierces the deep crural fascia to become subcutaneous at what distance proximal to the tip of the lateral malleolus?

. 2 to 4 cm
. 5 to 7 cm
. 10 to 12 cm
. 15 to 17 cm
. 20 to 22 cm

Correct Answer & Explanation

. 10 to 12 cm

Explanation

The superficial peroneal nerve typically transitions from the lateral compartment to the subcutaneous tissue by piercing the deep fascia approximately 10 to 12 cm proximal to the tip of the lateral malleolus. It is highly susceptible to iatrogenic injury in this zone during lateral leg approaches.

Question 8574

Topic: 2. Trauma

A 22-year-old soccer player develops an acute compartment syndrome of the leg following a tibial fracture. To adequately decompress the deep posterior compartment, the surgeon must identify and protect its neurovascular contents. Which of the following structures normally resides within the deep posterior compartment of the leg?

. Superficial peroneal nerve and peroneal artery
. Deep peroneal nerve and anterior tibial artery
. Sural nerve and lesser saphenous vein
. Tibial nerve and posterior tibial artery
. Saphenous nerve and greater saphenous vein

Correct Answer & Explanation

. Tibial nerve and posterior tibial artery

Explanation

The deep posterior compartment of the leg contains the tibialis posterior, flexor digitorum longus, flexor hallucis longus, tibial nerve, and posterior tibial and peroneal arteries.

Question 8575

Topic: 2. Trauma

A patient is treated nonoperatively for a closed proximal radius fracture. Four weeks later, they are unable to form a true "OK" sign, instead making a flat pinch with the thumb and index finger. Sensation in the hand is entirely normal. Which of the following muscles is definitively denervated?

. Flexor digitorum superficialis to the index finger
. Flexor carpi radialis
. Flexor pollicis longus
. Adductor pollicis
. Opponens pollicis

Correct Answer & Explanation

. Flexor pollicis longus

Explanation

The patient has Anterior Interosseous Nerve (AIN) syndrome, which innervates the flexor pollicis longus, flexor digitorum profundus (index/long), and pronator quadratus. Weakness of the FPL prevents flexion of the thumb IP joint, causing a flat pinch.

Question 8576

Topic: Lower Extremity Trauma

Following a traumatic posterior knee dislocation, a patient presents with an ischemic lower extremity. The popliteal artery is highly susceptible to stretch injury due to its fixed anatomic location between the adductor hiatus proximally and which of the following structures distally?

. Interosseous membrane
. Soleus arch
. Tibial plateau
. Superior extensor retinaculum
. Popliteus muscle belly

Correct Answer & Explanation

. Soleus arch

Explanation

The popliteal artery is firmly tethered proximally at the adductor hiatus and distally by the fibrous arch of the soleus muscle. This rigid fixation makes it vulnerable to severe stretch and intimal tearing during high-energy knee dislocations.

Question 8577

Topic: 2. Trauma

A patient develops acute compartment syndrome of the lateral compartment of the leg following a complex fibular shaft fracture. Which of the following nerves courses through this specific compartment and is at greatest risk for ischemic injury?

. Deep peroneal nerve
. Superficial peroneal nerve
. Sural nerve
. Saphenous nerve
. Tibial nerve

Correct Answer & Explanation

. Superficial peroneal nerve

Explanation

The lateral compartment of the leg contains the peroneus longus and brevis muscles, along with the superficial peroneal nerve. The deep peroneal nerve is located within the anterior compartment.

Question 8578

Topic: Lower Extremity Trauma

An orthopedic surgeon is evaluating an ankle MRI for a suspected syndesmotic injury. Which ligament in the syndesmotic complex constitutes the primary restraint to excessive anterior translation of the distal fibula relative to the tibia?

. Anterior inferior tibiofibular ligament
. Posterior inferior tibiofibular ligament
. Interosseous ligament
. Transverse tibiofibular ligament
. Deltoid ligament

Correct Answer & Explanation

. Anterior inferior tibiofibular ligament

Explanation

The anterior inferior tibiofibular ligament (AITFL) is the weakest of the syndesmotic ligaments but serves as the primary anatomical restraint against anterior translation of the distal fibula.

Question 8579

Topic: 2. Trauma

A patient undergoes a fasciotomy for acute compartment syndrome of the lower leg. The deep posterior compartment is decompressed. Which of the following structures is located most anteriorly and medially within the retromalleolar groove as it passes into the foot?

. Flexor hallucis longus
. Flexor digitorum longus
. Tibial nerve
. Posterior tibial artery
. Tibialis posterior

Correct Answer & Explanation

. Tibialis posterior

Explanation

From anterior/medial to posterior/lateral behind the medial malleolus, the structures are the Tibialis posterior, Flexor digitorum longus, Posterior tibial Artery, Tibial Nerve, and Flexor hallucis longus (Tom, Dick, AND Very Nervous Harry). The tibialis posterior is the most anterior and medial structure.

Question 8580

Topic: 2. Trauma

During an anterior intrapelvic (Stoppa) approach for an anterior column acetabular fracture, significant arterial hemorrhage is encountered as the dissection proceeds along the posterior aspect of the superior pubic ramus. This bleeding is most likely due to an injury to the 'corona mortis,' which is an anastomosis between which two vascular systems?

. Internal iliac and internal pudendal arteries
. Superior gluteal and internal iliac vessels
. External iliac and obturator vessels
. Femoral and inferior epigastric arteries
. Internal pudendal and external pudendal arteries

Correct Answer & Explanation

. Femoral and inferior epigastric arteries

Explanation

The 'corona mortis' (crown of death) represents 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 typically located crossing the superior pubic ramus at an average distance of 5 to 6 cm from the pubic symphysis. Iatrogenic injury during pelvic or acetabular surgery can result in life-threatening hemorrhage that is difficult to control.

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