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2. Trauma MCQs

Practice Set 639 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 12761

Topic: 2. Trauma
A 25-year-old woman sustains a transverse, "chalk-stick" fracture of her proximal tibia. Radiographs reveal diffuse osteosclerosis and a "rugger jersey" spine. She has no history of childhood anemia. Which gene mutation is most likely responsible?
. TCIRG1
. CLCN7
. CAII
. SQSTM1
. TRPS1

Correct Answer & Explanation

. CLCN7

Explanation

Autosomal dominant osteopetrosis (Albers-Schönberg disease) is the adult, milder form often discovered incidentally or after a chalk-stick fracture. It is most commonly caused by mutations in the CLCN7 gene (chloride channel).

Question 12762

Topic: 2. Trauma

A 30-year-old man with autosomal dominant osteopetrosis requires surgical fixation of a displaced transverse femoral shaft fracture. Which of the following is the most significant intraoperative challenge expected?

. Excessive intraoperative hemorrhage due to hypervascularity
. Obliterated medullary canal necessitating excessive reaming and drill bit breakage risk
. Severe cortical thinning preventing screw purchase
. Rapid heterotopic ossification post-fixation
. Hypercalcemia crisis upon intramedullary reaming

Correct Answer & Explanation

. Obliterated medullary canal necessitating excessive reaming and drill bit breakage risk

Explanation

Bones in osteopetrosis are extremely dense and brittle (marble bone), often lacking a distinct medullary canal. This makes intramedullary reaming and drilling incredibly difficult, with a high risk of heat necrosis and equipment breakage.

Question 12763

Topic: 2. Trauma

A 35-year-old male with autosomal dominant osteopetrosis sustains a subtrochanteric femur fracture. Which of the following principles must be considered during internal fixation?

. The bone has a wide medullary canal requiring oversized implants
. Reaming is usually unnecessary
. There is an increased risk of drill bit breakage and heat necrosis
. Healing relies solely on endochondral ossification
. The risk of nonunion is negligible

Correct Answer & Explanation

. There is an increased risk of drill bit breakage and heat necrosis

Explanation

Osteopetrotic bone is exceptionally dense and brittle. Surgeons must use sharp drill bits, cooling, and careful technique to avoid drill bit breakage and thermal necrosis during fixation.

Question 12764

Topic: 2. Trauma

A newborn is evaluated for severe posteromedial bowing of the left tibia and a calcaneovalgus foot deformity. What is the expected natural history of the lower limb deformity if managed conservatively?

. Progression to frank pseudarthrosis
. Complete spontaneous correction of both bowing and limb length discrepancy
. Resolution of bowing but residual leg length discrepancy at skeletal maturity
. Development of early-onset tibiotalar osteoarthritis
. High risk of pathologic fracture requiring prophylactic intramedullary nailing

Correct Answer & Explanation

. Resolution of bowing but residual leg length discrepancy at skeletal maturity

Explanation

Congenital posteromedial bowing of the tibia generally demonstrates spontaneous improvement of the angular deformity over time. However, it typically results in a residual limb length discrepancy of 3 to 7 cm at skeletal maturity, distinguishing its benign course from anterolateral bowing.

Question 12765

Topic: Upper Extremity Trauma

A 4-year-old girl is evaluated for neck asymmetry and limited shoulder abduction. Examination reveals a highly positioned, hypoplastic left scapula. During surgical correction via the Woodward procedure, which structure is typically excised to facilitate inferior mobilization of the scapula?

. Coracoid process
. Omovertebral bone
. Acromioclavicular joint
. Superior angle of the scapula only
. Pectoralis minor tendon

Correct Answer & Explanation

. Omovertebral bone

Explanation

Sprengel deformity is a congenital failure of scapular descent, often tethered by an omovertebral connection. The Woodward procedure involves excising the omovertebral bone or fibrous band and relocating the muscular origins to move the scapula inferiorly.

Question 12766

Topic: 2. Trauma
A 2-year-old boy presents with an established pseudarthrosis of the middle and distal thirds of the tibia. There is prominent anterolateral bowing, and he has multiple café-au-lait spots. Which of the following surgical techniques is most associated with obtaining union and preventing refracture in this challenging condition?
. Cast immobilization until skeletal maturity
. Excision of the pseudarthrosis and intramedullary rodding alone
. Excision of the pseudarthrosis, cross-union to the fibula, and intramedullary rodding
. External fixation with gradual angular correction without resection
. Isolated bone grafting of the pseudarthrosis site

Correct Answer & Explanation

. Excision of the pseudarthrosis, cross-union to the fibula, and intramedullary rodding

Explanation

Congenital pseudarthrosis of the tibia (often associated with NF1) has a notoriously high failure rate. Contemporary surgical management aims for complete resection of the hamartomatous tissue, stabilization with intramedullary rodding, and creation of a tibiofibular cross-union to maximize mechanical stability.

Question 12767

Topic: 2. Trauma

An asymptomatic 20-year-old woman undergoes lower extremity radiographs following minor trauma. The X-rays incidentally reveal bilateral, multiple dense longitudinal striations in the metaphyses and diaphyses of the distal femurs and proximal tibias. Her skull appears normal, and she has no hearing deficits. What is the most likely diagnosis?

. Osteopoikilosis
. Melorheostosis
. Osteopathia striata
. Pycnodysostosis
. Osteopetrosis

Correct Answer & Explanation

. Osteopathia striata

Explanation

Osteopathia striata (Voorhoeve disease) is a benign, asymptomatic bone dysplasia characterized by distinctive longitudinal linear densities in the metaphyses of long bones. It typically requires no specific treatment but must be differentiated from more severe sclerosing dysplasias like osteopathia striata with cranial sclerosis.

Question 12768

Topic: Lower Extremity Trauma

A patient with osteoarthritis presents with a varus knee deformity. Standing full-length radiographic analysis reveals a mechanical lateral distal femoral angle (mLDFA) of 88 degrees and a mechanical medial proximal tibial angle (mMPTA) of 78 degrees. What is the primary source of the mechanical axis deviation?

. Femoral shaft bowing
. Distal femur varus deformity
. Proximal tibia varus deformity
. Intra-articular knee joint wear
. Combined femoral and tibial deformity

Correct Answer & Explanation

. Proximal tibia varus deformity

Explanation

The normal mLDFA is 85-90 degrees (average 88) and normal mMPTA is 85-90 degrees (average 87). An mMPTA of 78 degrees is abnormally low, unequivocally indicating a proximal tibia varus deformity as the primary driver of the alignment anomaly.

Question 12769

Topic: Lower Extremity Trauma

Evaluating a lower extremity deformity, the mechanical axis deviation (MAD) falls deep into the lateral compartment of the knee. The mechanical lateral distal femoral angle (mLDFA) is 75 degrees and the medial proximal tibial angle (MPTA) is 88 degrees. What is the primary source of the deformity?

. Femoral varus
. Femoral valgus
. Tibial varus
. Tibial valgus
. Combined femoral and tibial valgus

Correct Answer & Explanation

. Femoral valgus

Explanation

The normal mLDFA is approximately 88 degrees. An mLDFA of 75 degrees indicates a smaller than normal angle, meaning the distal femur is structurally in severe valgus. The normal MPTA confirms the tibia is not contributing to the primary angular deformity.

Question 12770

Topic: Lower Extremity Trauma



When establishing reference lines for complex tibial deformity planning, the mechanical axis of the normal tibia is defined as a line connecting the center of the ankle plafond to which of the following proximal landmarks?

. The center of the tibial plateau
. The medial tibial spine
. The center of the intercondylar notch of the femur
. The lateral aspect of the medial tibial plateau
. The tip of the fibular head

Correct Answer & Explanation

. The center of the tibial plateau

Explanation

The mechanical axis of the tibia is defined by a straight line connecting the center of the proximal tibial plateau (often just medial to the lateral tibial spine) to the center of the distal tibial plafond.

Question 12771

Topic: 2. Trauma

When utilizing a hexapod external fixator (e.g., Taylor Spatial Frame) for lower extremity deformity correction, what is the primary consequence of inaccurately defining the 'mounting parameters'?

. Premature consolidation of the regenerate bone.
. Induction of new, unintended secondary deformities during the correction program.
. Mechanical failure and buckling of the struts.
. Increased rate of pin tract infections.
. Loss of stable fixation leading to hypertrophic nonunion.

Correct Answer & Explanation

. Induction of new, unintended secondary deformities during the correction program.

Explanation

Mounting parameters define the position of the reference ring relative to the reference bone fragment. If these are incorrect, the software calculates rotation and translation around an incorrect virtual hinge, inducing iatrogenic deformities.

Question 12772

Topic: Lower Extremity Trauma

When performing a medial opening wedge high tibial osteotomy (HTO) for isolated medial compartment osteoarthritis, restoring the mechanical axis to intersect the tibial plateau at what percentage of its width (from medial to lateral) is recommended for optimal load redistribution?

. 30-35%
. 50%
. 62-66%
. 75-80%
. 85-90%

Correct Answer & Explanation

. 62-66%

Explanation

For medial compartment osteoarthritis, an HTO aims to shift the weight-bearing axis laterally to offload the diseased medial compartment. The target correction is a slight valgus overcorrection, intersecting the 62% to 66% coordinate of the tibial plateau width.

Question 12773

Topic: Lower Extremity Trauma

A patient is planned for a medial opening wedge high tibial osteotomy (HTO) for medial compartment osteoarthritis with a varus deformity. To achieve optimal longevity of the joint, where should the postoperative mechanical axis line ideally pass through the knee?

. Through the center of the tibial spines.
. Through the center of the medial compartment.
. At the 62.5% coordinate of the tibial plateau from medial to lateral (Fujisawa point).
. At the 80% coordinate of the tibial plateau from medial to lateral.
. Slightly medial to the lateral tibial spine (40% coordinate).

Correct Answer & Explanation

. At the 62.5% coordinate of the tibial plateau from medial to lateral (Fujisawa point).

Explanation

The Fujisawa point corresponds to roughly 62-62.5% across the tibial plateau (from medial to lateral). Targeting the mechanical axis through this slightly lateral point reliably offloads the medial compartment and improves HTO survivorship.

Question 12774

Topic: 2. Trauma

To maximize the axial stiffness of an Ilizarov circular external fixator frame used for bone transport, which of the following mechanical modifications is most effective?

. Increasing the ring diameter.
. Decreasing the wire tension.
. Placing the rings further from the fracture/osteotomy site.
. Using wires that intersect at 90-degree angles.
. Using a half-pin instead of a tensioned wire.

Correct Answer & Explanation

. Using wires that intersect at 90-degree angles.

Explanation

Axial stiffness in a circular frame is maximized by using smaller diameter rings, tensioning the wires maximally, placing the rings close to the fracture site, and crossing wires at roughly 90 degrees.

Question 12775

Topic: Lower Extremity Trauma

When evaluating coronal plane lower extremity deformity, which of the following values indicates a pathologic varus deformity originating from the distal femur?

. mLDFA of 87 degrees
. mLDFA of 96 degrees
. mLDFA of 80 degrees
. MPTA of 87 degrees
. MPTA of 95 degrees

Correct Answer & Explanation

. mLDFA of 87 degrees

Explanation

The normal mechanical lateral distal femoral angle (mLDFA) is approximately 87 degrees. An mLDFA greater than 90 degrees indicates that the distal femur is in varus, while an mLDFA less than 85 degrees indicates valgus.

Question 12776

Topic: 2. Trauma

According to Paley's Rule 3 of deformity correction, if an osteotomy is performed at a level different from the Center of Rotation of Angulation (CORA) and the hinge is also placed at a location remote from the CORA, what is the expected outcome?

. Pure angular correction with complete restoration of the mechanical axis.
. Angular correction is achieved, but a secondary translation deformity is created.
. Complete failure of the osteotomy to close, resulting in nonunion.
. Pure translational correction without any angular change.
. The mechanical axes will become parallel and collinear seamlessly.

Correct Answer & Explanation

. Angular correction is achieved, but a secondary translation deformity is created.

Explanation

Rule 3 dictates that if neither the osteotomy nor the hinge axis is located at the CORA, angular correction will occur, but it will create a new, iatrogenic translation deformity (the mechanical axis lines will be parallel but not collinear).

Question 12777

Topic: 2. Trauma

When performing fixator-assisted intramedullary nailing for the correction of a diaphyseal femur deformity, what is the primary purpose of the temporarily applied external fixator?

. To provide continuous distraction osteogenesis postoperatively
. To completely bypass the need for distal interlocking screws
. To accurately maintain the corrected alignment in multiple planes while the intramedullary nail is inserted and locked
. To definitively manage active deep infection during nail insertion

Correct Answer & Explanation

. To accurately maintain the corrected alignment in multiple planes while the intramedullary nail is inserted and locked

Explanation

Fixator-assisted nailing utilizes a temporary external fixator to dial in and hold the exact desired multiplanar correction. This rigid temporary stabilization ensures the deformity is not lost during reaming and nail insertion.

Question 12778

Topic: 2. Trauma

A valgus-producing proximal femoral osteotomy is planned for a patient with a femoral neck nonunion. What is the primary biomechanical advantage of this procedure for achieving union?

. Increases the abductor moment arm
. Decreases the overall joint reaction force
. Converts shear forces across the nonunion into compressive forces
. Medializes the mechanical axis of the lower extremity
. Lengthens the gluteus medius muscle

Correct Answer & Explanation

. Converts shear forces across the nonunion into compressive forces

Explanation

A valgus intertrochanteric osteotomy reorients the vertical fracture line of a nonunion more horizontally. This converts destabilizing shear forces into compressive forces, promoting fracture healing.

Question 12779

Topic: 2. Trauma

When performing a fixator-assisted nailing (FAN) for an acute distal femoral deformity correction, what is the primary purpose of applying the temporary external fixator prior to reaming?

. To compress the osteotomy site
. To maintain the correction of translation and angulation during reaming
. To provide permanent definitive fixation
. To distract the fracture for leg lengthening
. To stimulate callus formation via micromotion

Correct Answer & Explanation

. To maintain the correction of translation and angulation during reaming

Explanation

In fixator-assisted nailing, the external fixator acts as a temporary rigid guide. It holds the desired alignment (preventing loss of translation and angulation correction) while the medullary canal is reamed and the nail is inserted.

Question 12780

Topic: Lower Extremity Trauma



A high tibial osteotomy (HTO) is planned for a patient with medial compartment osteoarthritis and varus alignment. To reliably unload the medial compartment and halt disease progression, the mechanical axis should be corrected to pass through which specific coordinate of the tibial plateau (measured from medial to lateral)?

. 30-40%
. 50% (neutral)
. 62-65% (Fujisawa point)
. 80-90%
. 100%

Correct Answer & Explanation

. 62-65% (Fujisawa point)

Explanation

To predictably relieve symptoms in a medial compartment HTO, the mechanical axis is intentionally shifted laterally to the Fujisawa point. This point is located at 62.5% of the tibial plateau width (measured from medial to lateral).

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