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2. Trauma MCQs

Practice Set 159 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 3161

Topic: 2. Trauma

When evaluating a standing long-leg radiograph of a 55-year-old female with osteoarthritis and a varus knee, the Joint Line Convergence Angle (JLCA) is measured at 6° (opening laterally). What does an abnormal JLCA primarily indicate in the context of deformity planning?

. A diaphyseal angular deformity
. A primary distal femoral varus malunion
. Intra-articular deformity, such as cartilage loss or ligamentous laxity
. A pure translational deformity of the proximal tibia
. A multi-apical deformity of the tibial shaft

Correct Answer & Explanation

. Intra-articular deformity, such as cartilage loss or ligamentous laxity

Explanation

The JLCA represents the angle between the articular surfaces of the distal femur and proximal tibia, normally 0°-2°. An increased JLCA typically indicates intra-articular pathology, such as asymmetric cartilage wear or collateral ligament laxity.

Question 3162

Topic: 2. Trauma

A patient is undergoing distraction osteogenesis for a leg length discrepancy. After the corticotomy, the surgeon instructs the patient to wait 7 days before initiating the distraction protocol. What is the primary biological purpose of this 'latency period'?

. To allow the pin sites to mature and prevent infection
. To allow the hematoma to organize and early callus to form
. To prevent acute compartment syndrome
. To stretch the neurovascular bundle prior to lengthening
. To allow the patient to adjust to the weight of the external fixator

Correct Answer & Explanation

. To allow the hematoma to organize and early callus to form

Explanation

The latency period (typically 5-7 days) allows the initial phase of fracture healing to begin, specifically the organization of the fracture hematoma and recruitment of osteoprogenitor cells, which is essential for optimal regenerate bone formation.

Question 3163

Topic: 2. Trauma

Which of the following is the most significant potential complication of distracting a bone segment at a rate faster than 1.5 mm per day during distraction osteogenesis?

. Premature consolidation of the regenerate
. Hypertrophic callus formation
. Poor regenerate formation leading to nonunion
. Excessive localized periosteal stripping
. Immediate acute nerve transection

Correct Answer & Explanation

. Poor regenerate formation leading to nonunion

Explanation

Distraction at a rate that is too fast (e.g., >1.5 mm/day) prevents adequate osteogenesis and typically results in poor, attenuated regenerate bone formation, ultimately leading to a nonunion or delayed union.

Question 3164

Topic: 2. Trauma

A surgeon is correcting a multi-apical tibial deformity using a Taylor Spatial Frame (TSF). The frame programming utilizes a 'Virtual Hinge'. What does the concept of a virtual hinge represent in six-axis hexapod external fixation?

. A physical articulated component connecting the rings that requires manual unlocking
. A computer-generated spatial point (often the CORA) around which the correction is calculated
. The intersection of the struts during maximum distraction
. The level of the master tab on the reference ring
. The diaphyseal midpoint of the reference bone segment

Correct Answer & Explanation

. A computer-generated spatial point (often the CORA) around which the correction is calculated

Explanation

In hexapod systems like the TSF, the 'Virtual Hinge' is a calculated point in space (usually matched to the CORA) around which the software directs all six struts to simultaneously correct angulation, translation, and rotation without needing a physical hinge mechanism.

Question 3165

Topic: 2. Trauma

When calculating the Bone Healing Index (BHI) for a patient who has undergone tibial lengthening via distraction osteogenesis, what formula is strictly utilized?

. Amount of lengthening achieved (cm) divided by the latency period (days)
. Total time in external fixation (days) divided by the amount of lengthening achieved (cm)
. Total time in external fixation (months) divided by the patient's age (years)
. The length of the regenerate (mm) divided by the daily distraction rate (mm/day)
. Total consolidation time (days) minus the distraction time (days)

Correct Answer & Explanation

. Total time in external fixation (days) divided by the amount of lengthening achieved (cm)

Explanation

The Bone Healing Index (BHI) is a standard metric defined as the total number of days the external fixator is worn divided by the total lengthening achieved in centimeters (days/cm). A lower BHI indicates faster healing.

Question 3166

Topic: 2. Trauma

Which technique describes Fixator-Assisted Nailing (FAN) in the context of deformity correction?

. Using a small external fixator strictly to transport a bone segment over an intact intramedullary nail
. Applying an external fixator to acutely correct the deformity, locking the alignment, reaming, and inserting an intramedullary nail, followed by fixator removal
. Leaving both an external fixator and an intramedullary nail in place for the entire duration of the consolidation phase
. Using temporary intramedullary Kirschner wires to guide an Ilizarov frame application
. Simultaneously distracting the bone with an external fixator while lengthening an expandable nail

Correct Answer & Explanation

. Applying an external fixator to acutely correct the deformity, locking the alignment, reaming, and inserting an intramedullary nail, followed by fixator removal

Explanation

Fixator-Assisted Nailing (FAN) involves using a temporary external fixator to accurately dial in an acute deformity correction. Once alignment is held by the fixator, the intramedullary nail is inserted to maintain the correction, and the fixator is immediately removed.

Question 3167

Topic: 2. Trauma

A 28-year-old male sustains a diaphyseal tibial fracture that heals in 15 degrees of varus. A deformity correction is planned. The surgeon places both the osteotomy and the mechanical hinge axis exactly at the Center of Rotation of Angulation (CORA). According to Paley's principles, which of the following best describes the resulting correction?

. The deformity will be corrected with an induced translation at the osteotomy site.
. The mechanical axis will be restored without any translation at the osteotomy site.
. The deformity will remain uncorrected due to a secondary translation deformity.
. The mechanical axis will shift laterally, creating a valgus malalignment.
. The osteotomy site will undergo compression rather than angulation.

Correct Answer & Explanation

. The mechanical axis will be restored without any translation at the osteotomy site.

Explanation

According to Paley's Osteotomy Rule 1, when both the osteotomy and the hinge are placed exactly at the CORA, the mechanical axis is fully restored. The bone segments will angulate perfectly without any induced translation at the osteotomy site.

Question 3168

Topic: 2. Trauma

A surgeon is planning to correct a pure translation deformity of the tibial diaphysis resulting from a prior malunion.

When tracing the proximal and distal anatomic axes of the tibia to find the Center of Rotation of Angulation (CORA), what geometric relationship will be observed?

. The axes will intersect perfectly at the exact center of the malunion.
. The axes will intersect at the level of the ankle joint.
. The axes will be parallel and will never intersect, placing the CORA at infinity.
. The axes will intersect at a 45-degree angle.
. The axes will intersect at multiple points forming a multi-apical CORA.

Correct Answer & Explanation

. The axes will be parallel and will never intersect, placing the CORA at infinity.

Explanation

In a pure translation deformity, there is no angulation, so the proximal and distal axes remain parallel. Mathematically and geometrically, parallel lines meet at infinity, meaning the CORA is at infinity.

Question 3169

Topic: 2. Trauma

A patient with a distal tibial malunion has a mechanical Posterior Proximal Tibial Angle (mPPTA) of 81 degrees and an Anterior Distal Tibial Angle (ADTA) of 100 degrees. What sagittal plane deformity does the ADTA value indicate?

. Normal sagittal alignment
. Proximal tibial procurvatum
. Distal tibial recurvatum
. Distal tibial procurvatum
. Proximal tibial recurvatum

Correct Answer & Explanation

. Distal tibial procurvatum

Explanation

The normal ADTA is approximately 80 degrees. An increased ADTA (e.g., 100 degrees) indicates a distal tibial procurvatum deformity (apex anterior angulation). The mPPTA of 81 degrees is within normal limits.

Question 3170

Topic: Lower Extremity Trauma

A 45-year-old female presents with a progressive valgus deformity of her right knee. Standing full-length radiographs reveal a mechanical axis deviation (MAD) of 30 mm lateral to the center of the knee. The mechanical lateral distal femoral angle (mLDFA) is 78°, the medial proximal tibial angle (MPTA) is 87°, and the joint line convergence angle (JLCA) is 1°. Based on Paley's malalignment test, which of the following is the primary source of the deformity?

. Tibial diaphyseal valgus
. Lateral ligamentous laxity
. Distal femoral valgus
. Medial collateral ligament contracture
. Intra-articular tibial plateau wear

Correct Answer & Explanation

. Distal femoral valgus

Explanation

Paley's malalignment test identifies the source of deformity. The normal mLDFA is approximately 88°; an mLDFA of 78° indicates a distal femoral valgus deformity, which aligns with the lateral MAD.

Question 3171

Topic: Lower Extremity Trauma

A 55-year-old male with medial compartment knee osteoarthritis presents with a varus thrust. Radiographs show a medial MAD of 40 mm, mLDFA of 87°, MPTA of 86°, and a JLCA of 7° opening laterally. What does the abnormal JLCA primarily signify in the context of deformity planning?

. A purely extra-articular diaphyseal tibial bowing
. A compensatory valgus deformity of the distal femur
. Intra-articular deformity or significant lateral collateral ligamentous laxity
. Normal joint mechanics expected with aging
. A fixed flexion contracture of the knee

Correct Answer & Explanation

. Intra-articular deformity or significant lateral collateral ligamentous laxity

Explanation

A normal JLCA is 0°-2°. An increased JLCA opening laterally in a varus knee suggests intra-articular cartilage loss (medial wear) or lateral ligamentous laxity, which must be accounted for to prevent undercorrection.

Question 3172

Topic: Lower Extremity Trauma

When analyzing the sagittal plane alignment of the tibia for deformity correction, which of the following represents the normal Posterior Proximal Tibial Angle (PPTA)?

. 90 degrees
. 87 degrees
. 81 degrees
. 75 degrees
. 65 degrees

Correct Answer & Explanation

. 81 degrees

Explanation

The normal PPTA (sagittal plane) is approximately 81° (range 77°-84°). This angle reflects the normal posterior slope of the tibial plateau, which is critical to maintain during high tibial osteotomies.

Question 3173

Topic: 2. Trauma

A patient is evaluated for chronic knee pain. Full-length radiographs reveal an mLDFA of 81° (valgus) and an MPTA of 81° (varus). The mechanical axis deviation (MAD) is exactly 0 mm, passing perfectly through the center of the knee. What is this clinical entity, and what is its primary long-term risk?

. Normal alignment; no increased risk
. Compensatory deformities; risk of early osteoarthritis due to shear forces from an oblique joint line
. Ligamentous laxity; risk of recurrent patellar dislocation
. Multi-apical diaphyseal deformity; risk of spontaneous fracture
. Intra-articular deformity; risk of arthrofibrosis

Correct Answer & Explanation

. Compensatory deformities; risk of early osteoarthritis due to shear forces from an oblique joint line

Explanation

This patient has a valgus femur and varus tibia that cancel each other out, yielding a normal MAD. This creates an oblique joint line (compensatory deformities), which generates pathological shear forces and leads to premature osteoarthritis.

Question 3174

Topic: Lower Extremity Trauma

A 60-year-old male presents with advanced medial compartment gonarthrosis and a varus deformity.

A high tibial osteotomy (HTO) is planned. The patient has a mechanical axis deviation (MAD) of 20 mm medial. If the surgeon aims to deliberately overcorrect the MAD to unload the medial compartment, where should the postoperative mechanical axis ideally pass through the tibial plateau?

. Exactly at the center (50% mark) of the tibial plateau
. At the 62% mark of the tibial plateau width (slightly lateral to the lateral tibial spine)
. At the 30% mark of the tibial plateau (medial compartment)
. At the 100% mark (extreme lateral edge of the plateau)
. Through the center of the medial femoral condyle

Correct Answer & Explanation

. At the 62% mark of the tibial plateau width (slightly lateral to the lateral tibial spine)

Explanation

For an HTO in the setting of medial compartment osteoarthritis, standard practice (Fujisawa point) dictates overcorrecting the mechanical axis to pass through approximately 62% to 62.5% of the tibial plateau width (measured medial to lateral) to adequately unload the medial compartment.

Question 3175

Topic: 2. Trauma

A patient with a distal third tibial malunion has a 15-degree procurvatum deformity and a 10-degree varus deformity. The surgeon plans a single-cut oblique osteotomy to correct both deformities simultaneously. In which plane is the true maximum deformity located?

. Coronal plane
. Sagittal plane
. Axial plane
. Oblique plane
. Transverse plane

Correct Answer & Explanation

. Oblique plane

Explanation

A deformity with components in both the coronal (varus) and sagittal (procurvatum) planes actually represents a single maximal angulation in an oblique plane, determined trigonometrically or via specialized software.

Question 3176

Topic: 2. Trauma

A 25-year-old sustains a tibial malunion. An osteotomy is performed 4 cm proximal to the CORA, and the fixation hinge is also placed at the osteotomy site (not at the CORA). Based on Paley's Rule 3, what is the consequence of this construct?

. Correction of angulation without translation
. Correction of angulation with expected translation at the osteotomy
. The proximal and distal mechanical axes will become parallel but not collinear
. The deformity will spontaneously translate to a collinear axis over time
. Joint line convergence angle (JLCA) will abnormally widen

Correct Answer & Explanation

. The proximal and distal mechanical axes will become parallel but not collinear

Explanation

Paley's Rule 3 dictates that if the osteotomy and hinge are both placed away from the CORA, the angular deformity is corrected but the mechanical axes will remain parallel and translated, failing to become collinear.

Question 3177

Topic: Lower Extremity Trauma

Evaluating a full-length standing radiograph of a 40-year-old female with bilateral knee pain, the mechanical axis deviation (MAD) is found to be 30mm lateral to the center of the right knee. Which of the following normal radiographic parameter values is most critical for determining if the deformity originates in the distal femur?

. Medial Proximal Tibial Angle (MPTA) of 87 degrees
. Mechanical Lateral Distal Femoral Angle (mLDFA) of 87 degrees
. Mechanical Lateral Proximal Femoral Angle (mLPFA) of 90 degrees
. Joint Line Convergence Angle (JLCA) of 5 degrees
. Posterior Proximal Tibial Angle (PPTA) of 81 degrees

Correct Answer & Explanation

. Mechanical Lateral Distal Femoral Angle (mLDFA) of 87 degrees

Explanation

A lateral MAD indicates valgus alignment. The mechanical Lateral Distal Femoral Angle (mLDFA) is essential for evaluating distal femoral deformity, with normal values being approximately 87 degrees.

Question 3178

Topic: 2. Trauma

A 45-year-old sustains a tibial shaft fracture that heals in 15 degrees of valgus and 10 degrees of procurvatum.

To accurately locate the CORA for this multiplanar deformity, how should the planning be conducted?

. Determine the CORA separately on orthogonal AP and lateral radiographs
. Calculate a single oblique plane of the deformity and find the CORA in that plane
. Perform osteotomies at two separate levels for each plane
. Rely solely on the sagittal plane as it dominates tibial mechanics
. Use only the anatomical axes and ignore the mechanical axes

Correct Answer & Explanation

. Calculate a single oblique plane of the deformity and find the CORA in that plane

Explanation

True multiplanar deformities exist as a single maximum angular deformity in an oblique plane. The geometric CORA is most accurately determined by calculating this single oblique plane.

Question 3179

Topic: 2. Trauma

A 28-year-old male with a post-traumatic distal tibial malunion requires correction. Preoperative assessment shows the mechanical Lateral Distal Tibial Angle (mLDTA) is abnormal. What is the generally accepted normal value for the mLDTA?

. 80 degrees
. 84 degrees
. 89 degrees
. 95 degrees
. 100 degrees

Correct Answer & Explanation

. 89 degrees

Explanation

The normal mechanical Lateral Distal Tibial Angle (mLDTA) is approximately 89 degrees (range 86-92 degrees), which helps evaluate coronal plane deformities of the distal tibia.

Question 3180

Topic: 2. Trauma

When performing a corticotomy for distraction osteogenesis in the tibial diaphysis, which of the following techniques is most essential to preserve the endosteal blood supply and optimize the regenerate bone?

. Using an oscillating saw with continuous saline irrigation
. Using a multiple drill-hole technique followed by an osteotome without violating the medullary canal excessively
. Performing a wide subperiosteal dissection
. Reaming the medullary canal extensively prior to corticotomy
. Using a high-speed burr through both cortices simultaneously

Correct Answer & Explanation

. Using a multiple drill-hole technique followed by an osteotome without violating the medullary canal excessively

Explanation

To preserve the endosteal and periosteal blood supply essential for distraction osteogenesis, a low-energy corticotomy using multiple drill holes and an osteotome is preferred over oscillating saws.

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