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2. Trauma MCQs

Practice Set 152 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 3021

Topic: Lower Extremity Trauma

A surgeon utilizes the Fixator-Assisted Nailing (FAN) technique to correct a severe distal tibial varus deformity. To guide the intramedullary nail and prevent recurrent deformity, blocking (Poller) screws are planned. Where must the blocking screws be placed relative to the medullary canal to achieve optimal correction?

. On the convex side of the deformity to widen the canal
. On the concave side of the deformity to narrow the canal and force the nail toward the convexity
. Directly within the center of the medullary canal at the level of the osteotomy
. Anteriorly in the proximal segment and posteriorly in the distal segment
. Exclusively within the dynamic locking slots of the nail

Correct Answer & Explanation

. On the concave side of the deformity to narrow the canal and force the nail toward the convexity

Explanation

Blocking screws are placed on the concave side of the deformity (the acute angle). This functionally narrows the canal, forcing the intramedullary nail toward the convexity and thereby correcting the deformity.

Question 3022

Topic: 2. Trauma

A patient with severe medial compartment osteoarthritis presents with a clinically apparent varus alignment. Radiographic analysis yields an mLDFA of 88 degrees, an MPTA of 86 degrees, and a mechanical axis deviation of 25 mm medial. The joint line convergence angle (JLCA) is 7 degrees, opening laterally. What is the most likely cause of the medial mechanical axis deviation?

. Distal femoral diaphyseal bowing
. Proximal tibial metaphyseal malunion
. Intra-articular deformity due to cartilage loss and ligamentous laxity
. Patellofemoral joint subluxation
. Congenital short femur

Correct Answer & Explanation

. Intra-articular deformity due to cartilage loss and ligamentous laxity

Explanation

The bony parameters (mLDFA and MPTA) are within normal limits (both normally ~87 degrees). An abnormal JLCA (>2 degrees) opening laterally indicates that the varus is intra-articular, driven by medial cartilage loss or lateral ligament laxity.

Question 3023

Topic: 2. Trauma

The Fixator-Assisted Nailing (FAN) technique combines external fixation principles with intramedullary nailing. Which of the following best describes the critical sequence of steps in the FAN technique?

. Reaming, followed by osteotomy, then application of the external fixator
. Osteotomy, intramedullary nailing, followed by external fixation for compression
. Application of external fixator, followed by osteotomy, deformity correction, and then intramedullary nailing
. Intramedullary nailing, followed by osteotomy and acute fixator adjustments
. Osteotomy, followed by blocking screw placement, plating, and final nailing

Correct Answer & Explanation

. Application of external fixator, followed by osteotomy, deformity correction, and then intramedullary nailing

Explanation

In the FAN technique, the external fixator is applied first to manipulate and hold the segments in the corrected alignment after the osteotomy. The bone is then rigidly fixed with an intramedullary nail before fixator removal.

Question 3024

Topic: Lower Extremity Trauma

Evaluation of sagittal plane alignment is crucial prior to proximal tibial osteotomy to avoid inadvertently altering knee kinematics. What is the approximate normal value for the posterior proximal tibial angle (PPTA)?

. 71 degrees
. 81 degrees
. 90 degrees
. 100 degrees
. 110 degrees

Correct Answer & Explanation

. 81 degrees

Explanation

The normal posterior proximal tibial angle (PPTA) is approximately 81 degrees (range 77-84 degrees), which reflects the normal physiological posterior slope of the tibial plateau.

Question 3025

Topic: 2. Trauma

The "Lengthening Over a Nail" (LON) technique is frequently utilized in modern limb lengthening. What is the primary clinical advantage of LON compared to classic distraction osteogenesis using solely a circular external fixator?

. Complete avoidance of intramedullary reaming
. Decreased risk of deep intramedullary infection
. Significantly reduced duration of external fixator wear
. Increased maximum daily rate of distraction
. Ability to immediately bear full weight on the affected extremity postoperatively

Correct Answer & Explanation

. Significantly reduced duration of external fixator wear

Explanation

The LON technique allows the external fixator to be removed immediately after the distraction phase is completed. The intramedullary nail maintains length and alignment during the consolidation phase, drastically reducing the time in the frame.

Question 3026

Topic: Lower Extremity Trauma

When executing a malalignment test on a standing full-length radiograph, the mechanical lateral distal femoral angle (mLDFA) is precisely measured. Which of the following correctly defines the mLDFA?

. The angle between the anatomical axis of the femur and the mechanical axis of the femur
. The angle between the mechanical axis of the tibia and the joint line of the distal femur
. The angle between the anatomical axis of the femur and the joint line of the distal femur
. The lateral angle formed between the mechanical axis of the femur and the joint line of the distal femur
. The medial angle formed between the femoral neck axis and the distal femoral joint line

Correct Answer & Explanation

. The lateral angle formed between the mechanical axis of the femur and the joint line of the distal femur

Explanation

The mLDFA is defined as the lateral angle formed by the intersection of the mechanical axis of the femur and the tangential line of the distal femoral condyles (joint line). It normally measures approximately 87 degrees.

Question 3027

Topic: Lower Extremity Trauma

A 48-year-old patient presents with a symptomatic genu varum deformity and confirmed significant lateral collateral ligament (LCL) laxity, leading to a varus thrust. Following the Paley Method, the orthopedic surgeon plans a proximal tibial osteotomy. What is the primary biomechanical rationale for intentionally overcorrecting the limb into 3 to 5 degrees of mechanical tibiofemoral valgus in this specific scenario?

. To reduce the overall limb length discrepancy
. To decrease the adduction moment by shifting the mechanical axis into the healthy lateral compartment
. To directly tighten the attenuated lateral collateral ligament
. To prevent future medial meniscal extrusion
. To improve patellofemoral tracking

Correct Answer & Explanation

. To decrease the adduction moment by shifting the mechanical axis into the healthy lateral compartment

Explanation

Correct Answer: BThe text clearly outlines the cornerstone concept: 'To effectively neutralize the powerful adduction moment and recenter the load over the tibial plateau in a ligamentously deficient knee, the surgeon mustintentionally overcorrectthe bony alignment.' It further states, 'The primary goal is to shift the mechanical axis from the diseased medial compartment, across the center of the knee, and into the healthy lateral compartment. For a varus knee with severe LCL laxity, this means overcorrecting the limb into at least 3 to 5 degrees of mechanical tibiofemoral valgus.' This overcorrection functionally compensates for the ligamentous instability by creating a stable bony alignment that prevents the joint from thrusting open. Overcorrection does not directly tighten the LCL, nor is its primary goal to reduce limb length discrepancy, prevent meniscal extrusion, or improve patellofemoral tracking in this context.

Question 3028

Topic: Lower Extremity Trauma

A 68-year-old female presents with severe medial compartment osteoarthritis, a 20mm medial Mechanical Axis Deviation (MAD), and a 7° laterally open Joint Line Convergence Angle (JLCA) on weight-bearing radiographs. She also exhibits a significant varus thrust during gait. Based on the Paley Method, what is the most appropriate surgical strategy to address both the bony malalignment and the ligamentous laxity?

. Perform a simple valgus-producing proximal tibial osteotomy to achieve a neutral mechanical axis.
. Perform an isolated lateral collateral ligament (LCL) reconstruction without bony correction.
. Perform a proximal tibial osteotomy to intentionally overcorrect the limb into 3-5 degrees of mechanical tibiofemoral valgus.
. Perform a distal femoral osteotomy to correct the varus, aiming for a neutral mechanical axis.
. Recommend non-operative management with bracing and physical therapy due to the complexity.

Correct Answer & Explanation

. Perform a proximal tibial osteotomy to intentionally overcorrect the limb into 3-5 degrees of mechanical tibiofemoral valgus.

Explanation

Correct Answer: CThis patient presents with both a significant bony varus deformity (20mm medial MAD) and clear evidence of ligamentous laxity (7° laterally open JLCA and varus thrust). The text emphasizes that 'Addressing the bony deformity alone in the face of significant ligamentous laxity is a recipe for catastrophic surgical failure.' It advocates for intentional overcorrection: 'To effectively neutralize the powerful adduction moment and recenter the load over the tibial plateau in a ligamentously deficient knee, the surgeon mustintentionally overcorrectthe bony alignment... For a varus knee with severe LCL laxity, this means overcorrecting the limb into at least 3 to 5 degrees of mechanical tibiofemoral valgus.' Therefore, performing a proximal tibial osteotomy (assuming the tibia is the primary bony deformity, which is common in varus) to achieve 3-5 degrees of mechanical tibiofemoral valgus is the most appropriate strategy. A simple correction to neutral (Option A) would leave the attenuated ligaments slack. Isolated LCL reconstruction (Option B) without addressing the underlying bony malalignment would likely fail due to persistent asymmetric loading. A distal femoral osteotomy (Option D) would only be appropriate if the primary bony deformity was femoral, and even then, overcorrection would be needed. Non-operative management (Option E) is unlikely to be effective for severe, symptomatic malalignment with ligamentous laxity.

Question 3029

Topic: Lower Extremity Trauma

A 30-year-old male presents with a chronic varus knee deformity and a history of a prior lateral knee injury. His standard double-leg stance long-leg radiograph shows a relatively well-aligned mechanical axis. However, a single-leg stance radiograph of the affected limb reveals a significant medial shift of the Mechanical Axis Deviation (MAD) and an increased Joint Line Congruency Angle (JLCA). What is the most critical implication of these findings for surgical planning?

. The patient's deformity is primarily osseous, and a simple high tibial osteotomy (HTO) based on the double-leg stance film will suffice.
. The dynamic shift in MAD and JLCA indicates significant LCL laxity that must be addressed concurrently with any bony correction.
. The single-leg stance radiograph is an unnecessary adjunct, as the double-leg stance film provides sufficient information for CORA calculation.
. The increased JLCA on single-leg stance suggests a fixed valgus deformity of the distal femur, requiring a distal femoral osteotomy.
. The medial shift of the MAD on single-leg stance implies a severe medial collateral ligament (MCL) injury, necessitating MCL repair.

Correct Answer & Explanation

. The dynamic shift in MAD and JLCA indicates significant LCL laxity that must be addressed concurrently with any bony correction.

Explanation

Correct Answer: BThe case explicitly states, 'In a patient suffering from LCL laxity, the MAD is not a static number; it is a dynamic variable that changes based on load.' It further clarifies that 'On a standard anteroposterior (AP) radiograph with the patient bearing weight equally on both legs, the MAD may appear completely normal or only mildly deviated... When the patient is instructed to stand solely on the affected limb, the LCL is fully challenged by the body's center of gravity. The lateral joint space gaps open, the knee thrusts into varus, and the MAD shifts dramatically medially, revealing the true, devastating extent of the functional malalignment.' This dynamic shift, coupled with an increased JLCA, is a direct indicator of LCL laxity. The implication for surgical planning is that both the bony deformity and the soft tissue laxity must be addressed.Option A is incorrectbecause the dynamic changes in MAD and JLCA clearly indicate a significant soft tissue component (LCL laxity) that cannot be ignored. Relying solely on the double-leg stance film would lead to an incomplete and likely failed correction.Option C is incorrectbecause the case emphasizes, 'single-leg stance radiographs are never optional. They are absolutely essential for unmasking the dynamic soft-tissue component of the deformity.'Option D is incorrectbecause an increased JLCA (medial convergence) and a medial shift of the MAD on single-leg stance are characteristic of LCL laxity causing varus instability, not a fixed valgus deformity of the distal femur.Option E is incorrectbecause a medial shift of the MAD and varus thrust are associated with lateral compartment instability (LCL), not MCL injury, which would typically lead to valgus instability and a lateral shift of the MAD.

Question 3030

Topic: 2. Trauma

A 35-year-old patient presents with a chronic varus knee deformity, a positive lateral thrust, and a JLCA of 4° on single-leg stance. The surgeon plans a gradual fibular transport with a circular external fixator. During the transport phase, the surgeon intentionally overtensions the LCL. What is the primary rationale for this intentional overtensioning?

. To compensate for anticipated stress relaxation of the ligamentous tissue after frame removal, ensuring a durable result.
. To induce a compensatory valgus deformity in the tibia, which is the preferred method for LCL laxity.
. To accelerate bone healing at the fibular osteotomy site, reducing overall treatment time.
. To prevent iatrogenic injury to the common peroneal nerve during the transport process.
. To allow for earlier removal of the external fixator, as the knee will be immediately stable.

Correct Answer & Explanation

. To compensate for anticipated stress relaxation of the ligamentous tissue after frame removal, ensuring a durable result.

Explanation

Correct Answer: AThe case explicitly lists 'The Ability to Overtension' as a key advantage of gradual correction: 'The surgeon can intentionally overtension the LCL during the transport phase to counteract the inevitable biological stress relaxation that occurs once the frame is removed, ensuring a durable, permanent long-term result.'Option B is incorrectbecause the case strongly condemns creating a compensatory valgus deformity (the 'overcorrection fallacy'). Overtensioning the LCL is about restoring ligamentous stability, not creating a new bony deformity.Option C is incorrectbecause overtensioning the LCL is related to ligamentous stability, not directly to accelerating bone healing at the fibular osteotomy site. Bone healing (regenerate formation) is a separate biological process.Option D is incorrectbecause the safety to the common peroneal nerve is primarily achieved by the location of the fibular osteotomy (distal to the nerve) and the gradual nature of the transport, not by overtensioning the ligament.Option E is incorrectbecause gradual transport inherently involves a period of external fixation. Overtensioning is for long-term durability, not for immediate frame removal, as the bone still needs to consolidate.

Question 3031

Topic: 2. Trauma

A patient with genu varum and a visible varus thrust presents for evaluation. The standing AP radiograph reveals a Joint Line Convergence Angle (JLCA) of 6 degrees diverging laterally. Based on Paley's principles, what does this increased JLCA primarily indicate?

. Medial meniscus tear
. Medial collateral ligament laxity
. Lateral collateral ligament (LCL) laxity
. Tibial plateau fracture malunion
. Normal physiological variant

Correct Answer & Explanation

. Lateral collateral ligament (LCL) laxity

Explanation

The normal JLCA is 0 to 2 degrees. A JLCA greater than 2 degrees that diverges laterally on a standing weight-bearing radiograph strongly indicates lateral soft-tissue laxity, primarily involving the LCL.

Question 3032

Topic: Lower Extremity Trauma

A 45-year-old male has a Mechanical Axis Deviation (MAD) of 30 mm medial to the knee center. His mechanical lateral distal femoral angle (mLDFA) is 88 degrees, and his medial proximal tibial angle (MPTA) is 80 degrees. Where is the primary site of the structural varus deformity?

. Distal femur
. Proximal tibia
. Knee joint soft tissues
. Diaphyseal femur
. Diaphyseal tibia

Correct Answer & Explanation

. Proximal tibia

Explanation

Normal mLDFA is 87° (range 85-90°) and normal MPTA is 87° (range 85-90°). An MPTA of 80° indicates a proximal tibial varus deformity, while the femoral alignment (mLDFA) is normal.

Question 3033

Topic: Lower Extremity Trauma

When planning a high tibial osteotomy for medial compartment osteoarthritis in a varus knee, the traditional target for the new mechanical axis is the Fujisawa point. Where is this point anatomically located on the tibial plateau?

. Center of the knee joint (50%)
. 30-40% lateral to the center of the tibial plateau
. 62% of the tibial plateau width from the medial edge
. 50% of the lateral compartment
. At the tip of the medial tibial spine

Correct Answer & Explanation

. 62% of the tibial plateau width from the medial edge

Explanation

The Fujisawa point is located approximately 62% of the way across the tibial plateau from medial to lateral. Passing the mechanical axis through this point creates 3 to 5 degrees of mechanical valgus, unloading the medial compartment.

Question 3034

Topic: 2. Trauma

Which of the following complications is more commonly associated with a lateral closing-wedge high tibial osteotomy compared to a medial opening-wedge high tibial osteotomy?

. Nonunion at the osteotomy site
. Common peroneal nerve palsy
. Patella baja
. Increased posterior tibial slope
. Medial collateral ligament avulsion

Correct Answer & Explanation

. Common peroneal nerve palsy

Explanation

Lateral closing-wedge HTO requires dissection near the proximal fibula and lateral tibial flare, placing the common peroneal nerve at a significantly higher risk of direct injury or tethering.

Question 3035

Topic: Lower Extremity Trauma



A patient undergoes Paley method evaluation for varus malalignment. The surgeon decides to measure the Joint Line Convergence Angle (JLCA) to evaluate soft tissue contributions. Which anatomical landmarks define the JLCA?

. The mechanical axis of the femur and the mechanical axis of the tibia
. The anatomical axis of the femur and the joint line of the tibia
. The tangential line of the distal femoral condyles and the tangential line of the proximal tibial plateau
. The transepicondylar axis and the mechanical axis of the tibia
. The mechanical axis of the femur and the anatomical axis of the tibia

Correct Answer & Explanation

. The tangential line of the distal femoral condyles and the tangential line of the proximal tibial plateau

Explanation

The JLCA is the angle formed between a line drawn tangent to the distal femoral articular condyles and a line drawn tangent to the proximal tibial articular plateau.

Question 3036

Topic: Lower Extremity Trauma

A 30-year-old male with symptomatic genu varum is found to have an mLDFA of 95 degrees and an MPTA of 88 degrees. What is the primary anatomic source of his mechanical axis deviation?

. Medial collateral ligament laxity
. Proximal tibial varus deformity
. Distal femoral varus deformity
. Distal femoral valgus deformity
. Proximal tibial valgus deformity

Correct Answer & Explanation

. Distal femoral varus deformity

Explanation

Normal mLDFA is 87° (range 85-90°). An mLDFA > 90° indicates a distal femoral varus deformity. Because the MPTA is normal (88°), the deformity is localized entirely to the distal femur.

Question 3037

Topic: Lower Extremity Trauma

A 50-year-old female presents with severe right knee varus. Her standing full-length radiographs demonstrate a mechanical axis deviation (MAD) of 45 mm medial to the center of the knee. The mechanical lateral distal femoral angle (mLDFA) is 88 degrees, and the medial proximal tibial angle (MPTA) is 75 degrees. What is the primary source of her varus deformity?

. Femoral shaft bowing
. Distal femoral intra-articular deformity
. Proximal tibial deformity
. Lateral collateral ligament laxity alone
. Combined femoral and tibial deformity

Correct Answer & Explanation

. Proximal tibial deformity

Explanation

The normal mLDFA is approximately 88 degrees, and the normal MPTA is approximately 87 degrees. An mLDFA of 88 degrees indicates no significant femoral deformity, whereas an MPTA of 75 degrees clearly indicates a severe proximal tibial varus deformity.

Question 3038

Topic: Lower Extremity Trauma

A patient with profound medial compartment osteoarthritis and varus thrust is planned for deformity correction. The surgeon notes that correcting the entire deformity through a single proximal tibial osteotomy would result in a medial proximal tibial angle (MPTA) of 98 degrees. What is the most appropriate surgical strategy according to Paley's principles?

. Proceed with the single-level high tibial osteotomy but use a lateral closing wedge technique.
. Perform a single-level medial opening wedge HTO and release the superficial medial collateral ligament.
. Perform a double-level osteotomy (distal femur and proximal tibia) to maintain joint line obliquity within physiological limits.
. Perform a single-level distal femoral osteotomy exclusively.
. Correct the tibial deformity and perform a concomitant LCL reconstruction to compensate for the joint line obliquity.

Correct Answer & Explanation

. Perform a double-level osteotomy (distal femur and proximal tibia) to maintain joint line obliquity within physiological limits.

Explanation

Correcting a severe deformity at a single level can result in abnormal joint line obliquity (MPTA > 95 degrees), which introduces pathological shear stresses on the articular cartilage. A double-level osteotomy is indicated to correct the mechanical axis while keeping the joint line parallel to the ground.

Question 3039

Topic: 2. Trauma

A 28-year-old presents with symptomatic genu varum. A standing radiograph shows an MPTA of 82 degrees. The surgeon plans a dome osteotomy of the proximal tibia. What is the primary biomechanical advantage of a dome osteotomy over a standard wedge osteotomy in this context?

. It requires a complete fibular osteotomy, ensuring immediate weight-bearing.
. It allows for correction of angulation without altering the length of the lower extremity.
. It completely avoids the risk of compartment syndrome.
. It allows for early ROM by bypassing the extensor mechanism.
. It prevents translation of the mechanical axis by functioning as an opening wedge.

Correct Answer & Explanation

. It allows for correction of angulation without altering the length of the lower extremity.

Explanation

A dome (cylindrical) osteotomy allows for angular correction without significantly altering leg length. It is highly versatile, permitting adjustments in the center of rotation, though it is technically demanding.

Question 3040

Topic: Lower Extremity Trauma

During the Paley malalignment test for a patient with severe genu varum,

you note the mechanical axis line falls entirely medial to the medial tibial plateau. If the MPTA is 80 degrees and the mLDFA is 88 degrees, where does the center of rotation of angulation (CORA) lie?

. In the distal third of the femur.
. At the level of the knee joint line.
. In the proximal tibia.
. In the lateral collateral ligament.
. In the midshaft of the tibia.

Correct Answer & Explanation

. In the proximal tibia.

Explanation

Because the mLDFA is normal (88 deg) and the MPTA is abnormal (80 deg), the deformity is entirely in the proximal tibia. Drawing the mechanical axis of the normal distal femur and the mechanical axis of the deformed tibia will result in an intersection (CORA) in the proximal tibia.

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