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2. Trauma MCQs

Practice Set 154 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 3061

Topic: Lower Extremity Trauma



A 45-year-old man undergoes deformity analysis. His standing lower extremity radiograph demonstrates a mechanical axis line that passes 15 mm medial to the center of the knee joint. What does this specific mechanical axis deviation (MAD) imply regarding the joint reactive forces at the knee?

. A balanced distribution of load across both medial and lateral compartments.
. An exponential increase in lateral compartment joint reactive forces.
. A substantially increased load across the medial compartment, predisposing to early osteoarthritis.
. A primary deformity driven solely by a depressed lateral tibial plateau.
. Reversal of the normal tensile forces in the lateral collateral ligament.

Correct Answer & Explanation

. A substantially increased load across the medial compartment, predisposing to early osteoarthritis.

Explanation

A medial mechanical axis deviation (MAD) indicates varus malalignment. This places disproportionately high joint reactive forces on the medial compartment of the knee, accelerating medial articular wear and cartilage breakdown.

Question 3062

Topic: 2. Trauma

A 60-year-old patient is being evaluated for a complex tibial deformity following a malunited fracture. The surgeon is planning a corrective osteotomy and reviews the following diagram:

The diagram illustrates the Center of Rotation of Angulation (CORA). Which of the following statements accurately describes the CORA and its primary importance in deformity correction?

. It is the point where the overall mechanical axis of the limb intersects the joint line, indicating the degree of Mechanical Axis Deviation (MAD).
. It represents the midpoint of the deformity, where the osteotomy should always be performed to achieve pure translation.
. It is the geometric apex where the proximal and distal mechanical axes of a deformed bone intersect, serving as the critical first step for surgical planning.
. It is the point of maximum angulation within the soft tissues, guiding soft tissue release rather than bone correction.
. It defines the ideal location for implant placement, ensuring maximal stability regardless of the osteotomy level.

Correct Answer & Explanation

. It is the geometric apex where the proximal and distal mechanical axes of a deformed bone intersect, serving as the critical first step for surgical planning.

Explanation

Correct Answer: CAs stated in the text, the Center of Rotation of Angulation (CORA) is the single most important concept in deformity planning. It is defined as 'the geometric apex of the deformity—the precise point where the proximal and distal mechanical axes of a deformed bone intersect.' Locating the CORA is described as 'the critical first step that dictates the entire surgical strategy.'Option A describes the mechanical axis deviation, not the CORA. Option B is incorrect; while the CORA is the epicenter, an osteotomy at the CORA with a hinge at the CORA achieves pure angular correction, not pure translation. Option D misrepresents the CORA's role, which is primarily for bone deformity. Option E is incorrect as implant placement stability is influenced by many factors, and the CORA's primary role is in planning the osteotomy and hinge placement for accurate correction.

Question 3063

Topic: 2. Trauma

A surgeon is correcting a complex mid-diaphyseal tibial deformity. The CORA is identified, but due to technical constraints, the osteotomy is performed 4 cm distal to the CORA, and the external fixator hinge is inadvertently placed 2 cm proximal to the CORA.

According to Paley's osteotomy rules, what is the most likely consequence of this surgical planning?

. Pure angular correction will be achieved without any translation.
. The correction will require a planned translation to achieve proper alignment.
. An undesirable secondary translation deformity will be induced, complicating the correction.
. The deformity will be undercorrected, requiring a second procedure.
. The osteotomy will be inherently unstable, leading to nonunion.

Correct Answer & Explanation

. An undesirable secondary translation deformity will be induced, complicating the correction.

Explanation

Correct Answer: CThis scenario applies Paley's Osteotomy Rule 3: 'When both the osteotomy and the hinge are placedaway from the CORA, an undesirable secondary translation deformity will be induced, complicating the correction.' In this case, the osteotomy is distal to the CORA, and the hinge is proximal to the CORA, meaning both are away from the CORA, leading to an unwanted translation.Option A describes Paley's Rule 1. Option B describes Paley's Rule 2. Options D and E are not the primary and most direct consequences described by Paley's Rule 3 regarding the geometric outcome of the correction.

Question 3064

Topic: 2. Trauma

A 45-year-old patient presents with a recurvatum deformity of the distal tibia after a conservatively managed fracture. When evaluating the sagittal plane on a lateral radiograph, what is the normal Anterior Distal Tibial Angle (ADTA)?

. 70 degrees
. 80 degrees
. 89 degrees
. 95 degrees
. 100 degrees

Correct Answer & Explanation

. 80 degrees

Explanation

The normal Anterior Distal Tibial Angle (ADTA) is approximately 80 degrees (range 78 to 82 degrees). A decreased ADTA represents a recurvatum (apex posterior) deformity, while an increased ADTA indicates a procurvatum deformity.

Question 3065

Topic: Lower Extremity Trauma

When assessing the mechanical axis of the tibia for deformity correction, which anatomical landmarks are used to define the proximal and distal points?

. Center of the tibial plateau to the center of the tibial plafond
. Medial tibial spine to the medial malleolus
. Center of the tibial tubercle to the lateral malleolus
. Lateral tibial spine to the center of the talus
. Center of the intercondylar eminence to the tip of the medial malleolus

Correct Answer & Explanation

. Center of the tibial plateau to the center of the tibial plafond

Explanation

The mechanical axis of the tibia is defined by a line drawn from the center of the proximal tibial plateau to the center of the distal tibial plafond.

Question 3066

Topic: 2. Trauma

A patient sustained a distal third tibia fracture treated with an intramedullary nail. The fracture healed with a 15 mm lateral translation but no angular deformity (mLDTA is 89 degrees). Where is the CORA located in a pure translational deformity?

. At the fracture site
. At the ankle joint line
. At the knee joint line
. At infinity
. Exactly midway between the knee and ankle

Correct Answer & Explanation

. At infinity

Explanation

In a pure translational deformity (parallel axes, no angulation), the proximal and distal segment axes never intersect. Therefore, the CORA is mathematically considered to be at infinity.

Question 3067

Topic: 2. Trauma

A patient presents with a healed tibial fracture with a 30-degree external rotation malunion but normal coronal and sagittal alignment. How does a pure rotational deformity typically affect the mechanical axis of the lower extremity?

. It causes a profound medial shift of the mechanical axis.
. It causes a lateral shift of the mechanical axis.
. It creates a multi-apical mechanical axis deviation.
. It does not alter the collinearity of the center of the hip, knee, and ankle.
. It invariably leads to a leg length discrepancy of greater than 2 cm.

Correct Answer & Explanation

. It does not alter the collinearity of the center of the hip, knee, and ankle.

Explanation

A pure rotational (torsional) malunion in the diaphysis does not displace the joint centers in the coronal or sagittal planes, and therefore does not alter the overall mechanical axis line of the extremity.

Question 3068

Topic: 2. Trauma

A varus malunion of the distal tibia creates a medial mechanical axis deviation (MAD) across the knee joint. If left untreated, what is the long-term consequence of this uncompensated distal malalignment on the knee?

. Lateral compartment osteoarthritis of the knee
. Medial compartment osteoarthritis of the knee
. Isolated patellofemoral arthritis
. Tear of the lateral collateral ligament
. Posterior cruciate ligament laxity

Correct Answer & Explanation

. Medial compartment osteoarthritis of the knee

Explanation

A distal varus deformity shifts the overall mechanical axis of the lower extremity medially. This increases the load on the medial compartment of the knee, predisposing the patient to premature medial compartment osteoarthritis.

Question 3069

Topic: 2. Trauma

During pre-operative planning for a distal tibial malunion, the surgeon realizes the osteotomy must be performed proximal to the CORA due to poor skin quality distally. If the angulation correction axis (ACA) is maintained at the CORA (Paley's Rule 2), what will be the resulting alignment?

. Pure angulation with no translation at the osteotomy site
. Incomplete correction of the mechanical axis with secondary rotational deformity
. Restoration of the mechanical axis accompanied by translation of the bone ends at the osteotomy site
. A secondary translational deformity resulting in mechanical axis deviation
. Complete correction of the deformity with inevitable joint line obliquity

Correct Answer & Explanation

. Restoration of the mechanical axis accompanied by translation of the bone ends at the osteotomy site

Explanation

According to Paley's Osteotomy Rule 2, when the ACA is placed at the CORA but the osteotomy is at a different level, the mechanical axis is completely realigned. However, this comes at the cost of obligatory translation of the bone segments at the osteotomy site.

Question 3070

Topic: 2. Trauma

A patient with a complex distal tibia malunion has an apex posterior (recurvatum) deformity. What clinical and radiographic findings are most characteristic of this specific deformity plane?

. Decreased ADTA and a clinical loss of plantarflexion
. Increased ADTA and a clinical loss of plantarflexion
. Decreased ADTA and a clinical loss of dorsiflexion
. Increased ADTA and a clinical loss of dorsiflexion
. Decreased LDTA with increased hindfoot eversion

Correct Answer & Explanation

. Decreased ADTA and a clinical loss of plantarflexion

Explanation

A recurvatum (apex posterior) deformity tilts the tibial plafond anteriorly (dorsally), which decreases the ADTA (normally 80 degrees). This orientation forces the ankle into relative dorsiflexion, clinically restricting the available arc of plantarflexion.

Question 3071

Topic: 2. Trauma

A patient with a distal tibial diaphyseal malunion is scheduled for corrective surgery. Preoperative planning identifies the Center of Rotation of Angulation (CORA). According to Paley's Osteotomy Rule 1, if both the osteotomy and the hinge axis are placed exactly at the CORA, what is the geometric result of the correction?

. Angular correction is achieved with a secondary translation created at the osteotomy site.
. Pure translation occurs without any angular change.
. Angular correction is achieved and the mechanical axes become colinear without translation.
. The mechanical axes become parallel but remain translated.
. Lengthening occurs without true angular correction.

Correct Answer & Explanation

. Angular correction is achieved and the mechanical axes become colinear without translation.

Explanation

Paley's Rule 1 states that if the osteotomy and the hinge are both placed at the CORA, the mechanical axes will completely realign without any translation. This results in a purely colinear mechanical axis.

Question 3072

Topic: 2. Trauma

A 45-year-old male presents with a stiff, painful ankle secondary to an apex anterior (procurvatum) malunion of the distal tibia. Which of the following radiographic angles is most likely abnormally decreased in this patient?

. Mechanical lateral distal tibial angle (mLDTA)
. Medial proximal tibial angle (MPTA)
. Anterior distal tibial angle (ADTA)
. Posterior proximal tibial angle (PPTA)
. Lateral proximal femoral angle (LPFA)

Correct Answer & Explanation

. Anterior distal tibial angle (ADTA)

Explanation

The normal ADTA is approximately 80 degrees. In a procurvatum (apex anterior) deformity, the distal tibial articular surface tilts posteriorly, which decreases the ADTA to below 80 degrees and causes anterior impingement.

Question 3073

Topic: Lower Extremity Trauma



A patient presents with a multi-apical deformity of the tibia. During preoperative templating, the surgeon defines the mechanical axes and identifies two distinct CORAs. What is the standard recommended strategy to perfectly correct this deformity without creating secondary translation?

. A single osteotomy at the proximal CORA with a hinge at the distal CORA.
. A single osteotomy exactly halfway between the two CORAs.
. Two separate osteotomies, each with a hinge placed at its respective CORA.
. A single opening wedge osteotomy at the apex of the larger deformity only.
. A transverse osteotomy through the diaphysis with immediate intramedullary nailing.

Correct Answer & Explanation

. Two separate osteotomies, each with a hinge placed at its respective CORA.

Explanation

For multi-apical deformities, the most precise way to achieve colinear mechanical axes without unwanted translation is to follow Paley's Rule 1 for each apex. This requires an osteotomy and hinge at each distinct CORA.

Question 3074

Topic: 2. Trauma

A 45-year-old male complains of restricted ankle dorsiflexion following nonoperative management of a distal third tibia fracture. Radiographs reveal an Anterior Distal Tibial Angle (ADTA) of 98 degrees. According to Paley's principles of deformity, which of the following is the most likely structural diagnosis?

. Apex anterior (procurvatum) deformity of the distal tibia
. Apex posterior (recurvatum) deformity of the distal tibia
. Normal sagittal alignment
. Sagittal translation without angulation
. Varus malunion

Correct Answer & Explanation

. Apex posterior (recurvatum) deformity of the distal tibia

Explanation

The normal ADTA is approximately 80 degrees. An increased ADTA (>80 degrees) indicates an apex posterior (recurvatum) deformity, which tilts the ankle joint anteriorly and limits dorsiflexion due to anterior osseous impingement.

Question 3075

Topic: 2. Trauma
A patient requires a medial opening wedge supramalleolar osteotomy for a distal tibial varus malunion. The desired angular correction is 15 degrees, and the width of the tibia at the planned osteotomy site is 40 mm. Using the standard trigonometric rule of thumb for osteotomies, what is the approximate base width of the required opening wedge?
. 5 mm
. 10 mm
. 15 mm
. 20 mm
. 25 mm

Correct Answer & Explanation

. 10 mm

Explanation

The rule of thumb for wedge calculations is: Base width = (Width of bone in mm × Angle of correction in degrees) / 60. In this scenario, (40 mm × 15) / 60 = 600 / 60 = 10 mm.

Question 3076

Topic: Lower Extremity Trauma

A 55-year-old female presents with a symptomatic varus knee deformity. Long-leg radiographs show a Mechanical Lateral Distal Femoral Angle (mLDFA) of 88° and a Medial Proximal Tibial Angle (MPTA) of 80°. Based on these measurements, where is the primary anatomical source of her deformity?

. Distal femur
. Proximal tibia
. Proximal femur
. Distal tibia
. Joint line convergence

Correct Answer & Explanation

. Proximal tibia

Explanation

Correct Answer: BThe text provides the normal value ranges for joint orientation angles. The normal mLDFA is 85° to 90° (Avg 87°). A value of 88° falls within this normal range, indicating that there is no significant valgus or varus deformity originating in the distal femur. The normal MPTA is 85° to 90° (Avg 87°). A value of 80° is less than 85°, which, according to the table, indicates a varus deformity originating in the proximal tibia. Therefore, the primary anatomical source of her varus deformity is the proximal tibia.Options A, C, D, and E are incorrect because the mLDFA is normal, ruling out the distal femur as the primary source, and the other angles (LPFA, mLDTA, JLCA) are not provided or are not the primary indicators for a varus knee deformity originating in the femur or tibia.

Question 3077

Topic: Lower Extremity Trauma

A 30-year-old patient requires correction of a severe valgus deformity of the distal femur. The CORA is located within the distal femoral epiphysis, making an osteotomy directly at the CORA impractical due to limited space for fixation. The surgeon plans to perform the osteotomy 5 cm proximal to the CORA, but still place the Angulation Correction Axis (ACA) at the CORA. According to Paley's principles, what is the expected outcome of this approach?

. A pure angular correction with no translation required.
. An unintended secondary translational deformity will inevitably occur.
. A pure angular correction will be achieved, but with obligatory translation at the osteotomy site.
. The mechanical axis will not be fully restored, leading to residual malalignment.
. The bone ends will remain perfectly apposed, maximizing surface area for healing.

Correct Answer & Explanation

. A pure angular correction will be achieved, but with obligatory translation at the osteotomy site.

Explanation

Correct Answer: CThis scenario perfectly describes Paley's Osteotomy Rule 2: Correction with Obligatory Translation. When anatomical constraints (like limited space in the epiphysis) prevent the osteotomy from being performed directly at the CORA, the osteotomy must be moved away from it. However, if the Angulation Correction Axis (ACA) is still placed at the CORA, a pure angular correction of the axis is still possible. The critical consequence is that the farther the osteotomy level is from the CORA, the more intentional translation is required at the osteotomy site to avoid creating secondary deformities and to keep the mechanical axis aligned. The amount of translation is mathematically predictable and essential for periarticular osteotomies.Option A is incorrect because translation is required. Option B is incorrect because if planned correctly (as per Rule 2), the translation is intentional and prevents anunintendedsecondary deformity. Option D is incorrect because the mechanical axiscanbe fully restored with planned translation. Option E is incorrect because translation means the bone ends will not be perfectly apposed, but rather intentionally offset.

Question 3078

Topic: 2. Trauma

A resident surgeon attempts to correct a proximal tibial varus deformity. They perform an osteotomy 3 cm distal to the CORA and place the external fixator hinge (ACA) 2 cm proximal to the CORA. Upon correction of the angular deformity, the post-operative radiograph shows a 'zig-zag' deformity and an altered final mechanical axis. Which of Paley's Osteotomy Rules was violated?

. Osteotomy Rule 1: The Ideal Pure Correction.
. Osteotomy Rule 2: Correction with Obligatory Translation.
. Osteotomy Rule 3: The Unintended Secondary Deformity.
. The Tension Band Principle.
. The principle of cortical apposition.

Correct Answer & Explanation

. Osteotomy Rule 3: The Unintended Secondary Deformity.

Explanation

Correct Answer: CThis clinical vignette illustrates a violation of Paley's Osteotomy Rule 3: The Unintended Secondary Deformity. This rule states that whenneitherthe osteotomy nor the Angulation Correction Axis (ACA) is located at the CORA, correcting the angular deformity willalwayscreate a secondary translational deformity. This unwanted shift alters the final mechanical axis, creates a 'zig-zag' deformity in the bone, and can induce new clinical problems. The resident's actions of placing the osteotomy distal to the CORA and the ACA proximal to the CORA directly lead to this outcome.Options A and B describe ideal or planned corrections. Options D and E relate to biomechanical principles of fixation, not the geometric rules of osteotomy planning.

Question 3079

Topic: 2. Trauma

During a complex oblique osteotomy of the tibia, the surgeon aims to maximize interfragmentary compression and neutralize shear forces. Which of the following techniques, as described in the case, would be most effective in achieving this goal?

. Placing the plate on the concave side of the deformity.
. Using a standard non-locking plate without over-contouring.
. Applying an independent lag screw perpendicular to the osteotomy line.
. Relying solely on locking screws to bridge a large gap.
. Ensuring the osteotomy is performed far from the CORA.

Correct Answer & Explanation

. Applying an independent lag screw perpendicular to the osteotomy line.

Explanation

Correct Answer: CThe text highlights several 'Surgical Pearls for Managing Shear and Axial Forces.' It explicitly states: 'For oblique or spiral osteotomies, a lag screw placed perfectly perpendicular to the osteotomy line provides absolute stability. It is the single most effective way to achieve interfragmentary compression and completely neutralize shear forces.' This technique directly addresses the goal of maximizing interfragmentary compression and neutralizing shear.Option A is incorrect as plating the concave side is biomechanically disadvantageous. Option B is incorrect because over-contouring is a pearl for convex plating, and non-locking plates rely on friction, which is less stable than a lag screw for shear. Option D, while locking screws provide fixed-angle stability, they are primarily for bridging gaps and resisting angular collapse, not for achieving direct interfragmentary compression across an osteotomy line in the same way a lag screw does. Option E is incorrect as performing an osteotomy far from the CORA (without proper planning) can lead to unintended deformities, not necessarily enhanced stability.

Question 3080

Topic: 2. Trauma

A patient requires a proximal tibial osteotomy for a complex deformity that necessitates a specific amount of translation to restore the mechanical axis, as per Paley's Rule 2. Which specialized plate design is specifically engineered to accommodate this planned translation and convert shear forces into compressive loads through the plate itself?

. A standard anatomical locking plate.
. A dynamic compression plate (DCP).
. A blade plate.
. A step plate.
. A tension band wiring construct.

Correct Answer & Explanation

. A step plate.

Explanation

Correct Answer: DThe text specifically discusses specialized hardware for managing translation. It states: 'Thestep plateis engineered specifically for this scenario. The plate features a built-in offset, or 'step,' that perfectly matches the planned translation. The primary biomechanical genius of the step plate is that the proximal bone fragment physically rests on the metallic step. This design converts dangerous shear forces into direct compressive loads that are transmitted through the structural integrity of the plate itself, rather than relying solely on the screws.' This directly matches the requirements of the question.Options A and B (standard anatomical locking plates and DCPs) are not designed with built-in translation. Option C (blade plate) is for high bending forces in periarticular regions, not primarily for planned translation. Option E (tension band wiring) is a different fixation method, not a plate designed for translation.

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