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2. Trauma MCQs

Practice Set 150 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 2981

Topic: 2. Trauma

A patient sustains a midshaft tibial fracture that heals with 2.5 cm of pure lateral translation but perfect angular alignment in both the sagittal and coronal planes. How will this purely translational malunion affect the mechanical axis deviation (MAD) and the joint orientation angles (MPTA, mLDFA)?

. Shifts MAD laterally and alters both MPTA and mLDFA
. Shifts MAD laterally but MPTA and mLDFA remain within normal limits
. MAD remains completely unchanged but MPTA increases significantly
. Shifts MAD medially and alters only MPTA
. Has absolutely no effect on either MAD or joint orientation angles

Correct Answer & Explanation

. Shifts MAD laterally but MPTA and mLDFA remain within normal limits

Explanation

Pure translation alters the mechanical axis line, shifting the MAD laterally in this case. However, because there is no angulation, the joint surfaces remain parallel to the ground, so the MPTA and mLDFA remain completely normal.

Question 2982

Topic: Lower Extremity Trauma

A 45-year-old female undergoes a medial opening wedge high tibial osteotomy (HTO) for medial compartment osteoarthritis. Intraoperatively, the surgeon inadvertently opens the anterior aspect of the osteotomy gap equally to the posterior aspect. What is the most likely consequence on the sagittal alignment of the tibia?

. Increase in the posterior tibial slope.
. Decrease in the posterior tibial slope.
. Maintenance of the native posterior tibial slope.
. Creation of an apex posterior translational deformity.
. Creation of an iatrogenic fixed flexion deformity.

Correct Answer & Explanation

. Increase in the posterior tibial slope.

Explanation

Because the proximal tibia is triangular, opening the anterior gap equally to the posterior gap will pitch the tibial plateau into relative extension, thereby increasing the posterior tibial slope. To maintain normal slope, the anterior gap must be smaller than the posterior gap (typically a 1:2 ratio).

Question 2983

Topic: Lower Extremity Trauma

A patient presents with an isolated structural procurvatum deformity of the distal femur. What is the most characteristic clinical symptom or physical examination finding associated with this specific sagittal plane deformity?

. Severe recurvatum of the knee during the stance phase of gait.
. A clinical fixed flexion deformity (FFD) of the knee.
. Patella alta and secondary extensor mechanism lag.
. An apparent lengthening of the affected lower extremity.
. Increased baseline passive knee hyperextension on the table.

Correct Answer & Explanation

. A clinical fixed flexion deformity (FFD) of the knee.

Explanation

An apex-anterior (procurvatum) deformity of the distal femur limits the mechanical extension of the knee joint. Clinically, this presents as an inability to fully extend the leg, mimicking a fixed flexion deformity.

Question 2984

Topic: Lower Extremity Trauma

When evaluating lower extremity alignment on standing full-length radiographs, a Joint Line Convergence Angle (JLCA) of 6 degrees is noted in a knee with severe varus deformity. According to Paley's principles, what does an abnormally elevated JLCA indicate?

. A purely extra-articular diaphyseal tibial deformity.
. Intra-articular deformity such as cartilage loss or ligamentous laxity.
. A compensatory deformity in the distal femur.
. A normal physiologic response to medial compartment loading.
. An apex-posterior sagittal plane deformity.

Correct Answer & Explanation

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

Explanation

The JLCA evaluates the parallelism of the distal femoral and proximal tibial articular surfaces. A normal JLCA is 0-2 degrees. An elevated JLCA indicates intra-articular pathology, typically cartilage volume loss or asymmetric ligamentous laxity.

Question 2985

Topic: Lower Extremity Trauma

A surgeon is planning a high tibial osteotomy (HTO) for a 45-year-old laborer with symptomatic medial compartment osteoarthritis and varus malalignment. To optimize load distribution, the postoperative mechanical axis should be targeted to pass through which specific coordinate of the tibial plateau?

. Exactly at the center (50%) of the tibial plateau.
. At the Fujisawa point, approximately 62% of the width from the medial edge.
. At the medial tibial spine, approximately 40% of the width from the medial edge.
. At the far lateral edge, approximately 85% of the width from the medial edge.
. At the center of the medial compartment to stimulate fibrocartilage growth.

Correct Answer & Explanation

. At the Fujisawa point, approximately 62% of the width from the medial edge.

Explanation

For medial compartment osteoarthritis, HTO aims to slightly overcorrect alignment into valgus. The optimal target is the Fujisawa point, located at 62-62.5% of the tibial width from the medial border, which appropriately unloads the medial compartment.

Question 2986

Topic: Lower Extremity Trauma

A 16-year-old patient presents with a symptomatic apex anterior (procurvatum) deformity of the distal femur. A single-level corrective osteotomy is planned. Which of the following osteotomy configurations is biomechanically appropriate to correct this sagittal deformity?

. Anterior opening wedge or posterior closing wedge.
. Anterior closing wedge or posterior opening wedge.
. Medial closing wedge.
. Lateral opening wedge.
. Pure transverse rotational osteotomy.

Correct Answer & Explanation

. Anterior closing wedge or posterior opening wedge.

Explanation

An apex anterior (procurvatum) deformity requires extension of the distal fragment. This is achieved by taking an anterior closing wedge or creating a posterior opening wedge at the level of the deformity.

Question 2987

Topic: Lower Extremity Trauma

During the preoperative planning for a distal femoral osteotomy using Paley's Malalignment Test, the surgeon draws a mechanical axis line from the center of the femoral head to the center of the ankle. The line falls 25 mm medial to the center of the knee. The MPTA is measured at 88 degrees, and the mLDFA is measured at 100 degrees. What is the primary source of the deformity?

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

Correct Answer & Explanation

. Femoral varus.

Explanation

The mechanical axis deviation (MAD) is medial, indicating a varus lower extremity. The MPTA is normal (87 +/- 3), but the mLDFA is abnormally high (100 degrees, normal is 87), indicating the primary structural varus deformity is located in the distal femur.

Question 2988

Topic: Lower Extremity Trauma

When evaluating the sagittal plane alignment of the distal femur, which of the following angles represents the normal anatomic posterior distal femoral angle (aPDFA)?

. 70 degrees
. 83 degrees
. 90 degrees
. 95 degrees
. 100 degrees

Correct Answer & Explanation

. 83 degrees

Explanation

The normal anatomic posterior distal femoral angle (aPDFA) in the sagittal plane is approximately 83 degrees. Deviations from this angle indicate an osseous procurvatum or recurvatum deformity in the distal femur.

Question 2989

Topic: Lower Extremity Trauma

When using a Taylor Spatial Frame to gradually correct a severe soft-tissue knee flexion contracture, where should the virtual hinge be placed to prevent iatrogenic joint subluxation?

. At the anterior cortex of the distal femur
. At the posterior joint line of the tibia
. At the instant center of rotation of the knee joint
. At the CORA of the tibial diaphysis
. At the tibial tubercle

Correct Answer & Explanation

. At the instant center of rotation of the knee joint

Explanation

To correct a knee joint contracture without causing iatrogenic subluxation or compression, the hinge (or virtual hinge) must be placed at the anatomical axis of rotation of the joint, which is the instant center of rotation located in the posterior femoral condyles.

Question 2990

Topic: 2. Trauma

A patient presents with a severe distal femoral procurvatum deformity following a malunited fracture. On physical examination, the patient demonstrates a clinical fixed flexion deformity (FFD) of 20 degrees. However, full-length lateral radiographs reveal a true osseous procurvatum of 40 degrees. Which of the following factors best explains the discrepancy between the clinical FFD and the osseous deformity magnitude according to Paley's principles?

. Associated posterior capsular contracture
. Associated anterior capsular contracture
. Compensatory hyperextension of the knee joint
. Compensatory flexion of the hip joint
. Ligamentous laxity of the posterior cruciate ligament

Correct Answer & Explanation

. Associated posterior capsular contracture

Explanation

In an osseous procurvatum deformity, the bone is bent into flexion. The clinical FFD is often less than the true osseous deformity magnitude because the posterior soft tissues and joint capsule may still allow compensatory hyperextension of the joint relative to the deformed distal femoral articular surface.

Question 2991

Topic: Lower Extremity Trauma

A 32-year-old male presents with chronic right knee pain and a progressive varus deformity. Standing long-leg radiographs reveal a Mechanical Axis Deviation (MAD) of 25mm medial to the center of the knee. Further analysis shows a Mechanical Lateral Distal Femoral Angle (mLDFA) of 88° and a Medial Proximal Tibial Angle (MPTA) of 75°. The Joint Line Convergence Angle (JLCA) is 1°. Based on Paley's principles, which of the following statements best describes the location and nature of this patient's deformity?

. The deformity is primarily femoral, requiring a distal femoral osteotomy.
. The deformity is intra-articular, indicating significant cartilage wear or ligamentous laxity.
. The deformity is entirely tibial, localized to the proximal tibia.
. The deformity is a combined femoral and tibial malalignment, requiring a bi-level osteotomy.
. The MAD is within normal limits, suggesting no significant extra-articular deformity.

Correct Answer & Explanation

. The deformity is entirely tibial, localized to the proximal tibia.

Explanation

Correct Answer: CThe patient presents with a significant varus deformity, indicated by the MAD of 25mm medial to the center of the knee (normal is 8-10mm medial). To localize the deformity, we use the joint orientation angles. The mLDFA is 88°, which is within the normal range (85-90°, average 88°), indicating no significant deformity in the distal femur. However, the MPTA is 75°, which is significantly outside the normal range (85-90°, average 87°). An abnormal MPTA points directly to a tibial-based deformity, specifically in the proximal tibia. The JLCA of 1° is normal (0-2°), ruling out significant intra-articular pathology as the primary cause of the angular deformity.Option A is incorrectbecause the mLDFA is normal, ruling out a primary femoral deformity.Option B is incorrectbecause the JLCA is normal, suggesting the primary issue is extra-articular bony malalignment, not intra-articular pathology or laxity.Option D is incorrectbecause the mLDFA is normal, localizing the deformity solely to the tibia.Option E is incorrectbecause a MAD of 25mm medial is significantly abnormal, indicating a clear varus deformity.

Question 2992

Topic: Lower Extremity Trauma

A 55-year-old patient presents with a severe tibial varus deformity, as shown in the preoperative planning radiograph below. The surgeon has meticulously drawn the mechanical axes of the proximal and distal tibial segments, identifying their intersection point. Which of the following statements accurately describes the significance of this intersection point in Paley's methodology?

. It represents the ideal location for the intramedullary nail entry point.
. It is the point where the mechanical axis of the entire limb should pass after correction.
. It is the Center of Rotation of Angulation (CORA), dictating the ideal osteotomy and hinge placement.
. It signifies the maximum point of cartilage wear in the knee joint.
. It indicates the optimal position for interference (Poller) screw placement.

Correct Answer & Explanation

. It is the Center of Rotation of Angulation (CORA), dictating the ideal osteotomy and hinge placement.

Explanation

Correct Answer: CThe image on the left (a) in the provided figure demonstrates the identification of the Center of Rotation of Angulation (CORA). The CORA is the geometric point where the proximal and distal mechanical (or anatomic) axes of a deformed bone intersect. According to Paley's principles, identifying the CORA is the single most important step in preoperative planning as it dictates the ideal location for the osteotomy and governs the mechanical behavior of the entire limb during correction. Placing the osteotomy and the hinge of correction (ACA) at the CORA (Rule One) allows for pure angulation correction without translation.Option A is incorrect. The nail entry point is typically suprapatellar or parapatellar for the tibia, not necessarily at the CORA.Option B is incorrect. The mechanical axis of the entire limb is drawn from the femoral head to the ankle mortise, and its restoration is the goal, but the intersection of thesegmentalaxes defines the CORA.Option D is incorrect. While severe deformity can lead to cartilage wear, the CORA is a geometric construct for bony deformity, not a direct indicator of cartilage pathology.Option E is incorrect. Poller screws are placed strategically around the nail in the metaphysis to prevent toggle, which is related to the corrected alignment, not the CORA itself.

Question 2993

Topic: 2. Trauma

A 60-year-old patient with severe bilateral genu varum is undergoing surgical correction. The surgeon plans to use Fixator Assisted Nailing (FAN) for the tibial deformities. Which of the following statements best describes the primary advantage of the FAN technique over traditional methods using only circular external fixators for such complex deformities?

. FAN completely eliminates the need for any form of internal fixation.
. FAN allows for gradual correction of the deformity over several weeks post-surgery.
. FAN combines the precision of temporary external fixation with the biological advantages of intramedullary nailing, allowing for immediate frame removal.
. FAN is primarily used for limb lengthening procedures, not angular correction.
. FAN significantly increases the risk of pin tract infections compared to traditional external fixation.

Correct Answer & Explanation

. FAN combines the precision of temporary external fixation with the biological advantages of intramedullary nailing, allowing for immediate frame removal.

Explanation

Correct Answer: CFixator Assisted Nailing (FAN) is a hybrid technique that combines the multi-planar precision of external fixation with the biological and mechanical superiority of intramedullary nailing. The external fixator is appliedtemporarilyin the operating room to achieve acute, millimeter-accurate correction of the deformity. Once corrected, an intramedullary nail is inserted and locked, and the external fixator is removed before the patient leaves the operating room. This allows the patient to benefit from the stability of internal fixation, early mobilization, and avoids the prolonged complications associated with long-term external frame wear.Option A is incorrect. FAN relies on intramedullary nailing as the definitive internal fixation.Option B is incorrect. FAN achievesacutecorrection in the operating room. Gradual correction is characteristic of long-term external fixator use.Option D is incorrect. While FAN can be adapted for lengthening, its primary strength lies in precise angular and translational deformity correction.Option E is incorrect. By removing the external fixator immediately, FAN significantlyreducesthe risk of long-term pin tract infections and other frame-related complications compared to prolonged external fixation.

Question 2994

Topic: 2. Trauma

During a Fixator Assisted Nailing (FAN) procedure for a proximal tibial varus deformity, the surgeon is preparing to place the half-pins for the monolateral external fixator. To ensure an unimpeded path for the intramedullary reamers and the definitive nail, what is the ideal strategic placement for these pins in the proximal and distal fragments?

. Two half-pins anteriorly in the proximal fragment and two anteriorly in the distal fragment.
. Two half-pins medially in the proximal fragment and two laterally in the distal fragment.
. Two half-pins posteriorly in the proximal fragment and two posteriorly in the distal fragment.
. Two half-pins directly through the planned medullary canal in both fragments.
. A single half-pin in each fragment, placed eccentrically to avoid the nail.

Correct Answer & Explanation

. Two half-pins posteriorly in the proximal fragment and two posteriorly in the distal fragment.

Explanation

Correct Answer: CThe case explicitly states the ideal strategy for tibial FAN pin placement: 'place two half-pins posteriorly in the proximal fragment and two posteriorly in the distal fragment. This posterior placement leaves the entire anterior-to-posterior and medial-to-lateral trajectory of the medullary canal completely free and unimpeded.' This ensures that the guide wire, reamers, and intramedullary nail can be inserted without obstruction from the external fixator pins.Option A is incorrectas anterior placement would obstruct the typical anterior entry point and reaming path for a tibial nail.Option B is incorrectas medial/lateral placement could obstruct the nail's path, especially if the nail is placed centrally or slightly off-center.Option D is incorrectas placing pins directly through the medullary canal would make intramedullary nailing impossible.Option E is incorrect. While eccentric placement is key, using only a single pin per fragment would provide insufficient stability for acute correction and holding the alignment for nailing.

Question 2995

Topic: 2. Trauma

Following a Fixator Assisted Nailing (FAN) procedure for a proximal tibial varus deformity, the external fixator is removed, and the intramedullary nail is locked. The surgeon then considers the need for interference (Poller) screws. The close-up fluoroscopic image below shows two interference screws strategically placed on the medial side of the nail in the proximal tibia. What is the primary biomechanical purpose of these screws in this specific context?

. To provide additional rotational stability to the nail in the diaphysis.
. To prevent the nail from migrating proximally or distally within the canal.
. To block the nail from drifting medially, thereby preventing recurrence of the varus deformity.
. To facilitate bone healing by compressing the osteotomy site.
. To serve as a temporary guide for reaming the medullary canal.

Correct Answer & Explanation

. To block the nail from drifting medially, thereby preventing recurrence of the varus deformity.

Explanation

Correct Answer: CThe image clearly shows two interference (Poller) screws placed on the medial side of the intramedullary nail in the proximal tibia. The case describes the 'bell-clapper effect,' where the nail can toggle or slide within the wide metaphyseal canal, leading to loss of correction. For a varus deformity, the bone tends to settle back into varus, meaning the nail would drift medially. Therefore, placing Poller screws on themedialside of the nail physically blocks this medial drift, creating a rigid channel that forces the nail to maintain the limb's newly corrected alignment and preventing recurrence of the varus deformity.Option A is incorrect. While they contribute to overall stability, their primary role in the metaphysis is to prevent translation/toggle, not specifically rotational stability in the diaphysis (which is handled by locking screws).Option B is incorrect. Proximal/distal migration is prevented by the proximal and distal locking screws of the nail.Option D is incorrect. Poller screws do not primarily compress the osteotomy site; their role is to control nail position within the canal.Option E is incorrect. While Poller screwscanbe placed before nailing to guide reaming and nail insertion, their primary biomechanical purposeafternail insertion and locking is to block unwanted translation and maintain correction.

Question 2996

Topic: Lower Extremity Trauma

A 35-year-old patient undergoes Fixator Assisted Nailing (FAN) for a valgus deformity of the distal femur. The deformity has been acutely corrected, and the intramedullary nail is in place. To prevent the 'bell-clapper effect' and maintain the corrected alignment, the surgeon plans to insert interference (Poller) screws. According to the golden rules for Poller screw placement, where should these screws be strategically positioned?

. On the medial side of the nail, in the acute angle of the deformity.
. On the lateral side of the nail, in the acute angle of the deformity.
. Anterior to the nail, in the sagittal plane.
. Posterior to the nail, in the sagittal plane.
. Proximal and distal to the nail's locking screws.

Correct Answer & Explanation

. On the lateral side of the nail, in the acute angle of the deformity.

Explanation

Correct Answer: BThe golden rule for interference screw placement is to 'Place on the Concave Side of the Deformity' and 'Place in the Acute Angle'. For a valgus deformity, the concavity is on thelateralside of the limb. Therefore, to block the nail from drifting laterally and prevent the bone from settling back into a valgus position, the blocking screws must be placed on thelateralside of the nail. They are placed in the acute angle formed by the nail and the bone's axis to effectively narrow the canal and prevent toggle.Option A is incorrect. Medial placement would be for a varus deformity, not valgus.Option C and D are incorrect. While Poller screws can be placed in the sagittal plane, the primary rule for angular deformity correction is based on the coronal plane concavity/convexity. Anterior/posterior placement would address sagittal plane instability, but for a valgus deformity (coronal plane), lateral placement is key.Option E is incorrect. Poller screws are placedaroundthe nail, typically in the metaphyseal region where the canal is wide, not specifically proximal or distal to the locking screws, which have a different function.

Question 2997

Topic: 2. Trauma

The multi-panel image below illustrates the journey of a patient undergoing Fixator Assisted Nailing (FAN) for bilateral bowleg deformities. Panel (g) shows the postoperative clinical appearance, and panel (e) shows the postoperative standing long-leg radiograph. What critical aspect of deformity correction is best demonstrated by the comparison of the preoperative state (f) and the postoperative results (e and g)?

. The ability of FAN to achieve gradual limb lengthening over several months.
. The necessity of prolonged external fixation for complex multiplanar deformities.
. The precise restoration of the mechanical axis and dramatic cosmetic and functional improvement achieved by acute correction.
. The primary role of interference screws in providing rotational stability throughout the diaphysis.
. The creation of a controlled translational deformity to balance joint forces.

Correct Answer & Explanation

. The precise restoration of the mechanical axis and dramatic cosmetic and functional improvement achieved by acute correction.

Explanation

Correct Answer: CThe multi-panel image, particularly comparing the preoperative varus deformity (f) with the postoperative aligned limbs (g) and the perfectly restored mechanical axis on the standing long-leg radiograph (e), highlights the power of combining Paley's principles with the FAN technique. The case emphasizes that FAN achieves 'a beautifully restored mechanical axis' and 'dramatic cosmetic and functional improvement' through acute correction. This demonstrates the ability to reliably restore normal biomechanics and improve patient quality of life.Option A is incorrect. FAN achievesacutecorrection, not gradual lengthening over months. Gradual lengthening is characteristic of long-term external fixator use.Option B is incorrect. FAN's advantage is precisely toavoidprolonged external fixation by using it temporarily and then removing it.Option D is incorrect. While interference screws are important, their primary role is to prevent toggle and maintain alignment in the metaphysis, not provide rotational stability throughout the diaphysis (which is the role of the nail's locking screws).Option E is incorrect. While Rule Two involves obligatory translation, the goal is always to restore the mechanical axis, not to create a 'controlled translational deformity' as an end goal in itself, unless addressing a pre-existing translational deformity. The overall outcome shown is perfect alignment, not a deliberate residual translational deformity.

Question 2998

Topic: 2. Trauma

A 55-year-old female presents with a severe post-traumatic varus malunion of the distal femur. Preoperative planning reveals a CORA located 5 cm proximal to the knee joint line, within the diaphyseal bone. The surgeon plans a distal femoral osteotomy. Given the CORA's location, the surgeon decides to perform the osteotomy directly at the CORA. Which of Paley's Osteotomy Rules applies to this scenario, and what is the expected outcome regarding correction?

. Rule 2 applies; the correction will require both angulation and translation at the osteotomy site to restore the mechanical axis.
. Rule 3 applies; a secondary translational deformity will be created if only angulation is performed.
. Rule 1 applies; a pure angular correction (hinging) at the osteotomy site will perfectly realign the mechanical axis without translation.
. Rule 1 applies; however, translation will still be necessary to achieve the desired mLDFA of 87 degrees.
. Rule 2 applies; the osteotomy must be performed away from the CORA to allow for stable internal fixation, necessitating translation.

Correct Answer & Explanation

. Rule 1 applies; a pure angular correction (hinging) at the osteotomy site will perfectly realign the mechanical axis without translation.

Explanation

Correct Answer: CRule 1 applies; a pure angular correction (hinging) at the osteotomy site will perfectly realign the mechanical axis without translation. The case explicitly states that the osteotomy is performed 'directly at the level of the CORA.' According to the text and diagram (specifically panel A of the image), Paley's Osteotomy Rule One states: 'When the osteotomy is performeddirectly at the level of the CORA, a pure angular correction (hinging) will perfectly realign the mechanical axis. No translation is required.'Incorrect Options:A:Rule 2 applies when the osteotomy isdifferent from the CORA, requiring both angulation and translation. This is contrary to the scenario described.B:Rule 3 describes a common pitfall when the osteotomy isdifferent from the CORAand angulation occurs without translation, leading to malalignment. This is not applicable when the osteotomy is at the CORA.D:Rule 1 explicitly states 'No translation is required' when the osteotomy is at the CORA. The mLDFA is a target angle, but its achievement through a Rule 1 osteotomy does not require translation.E:Rule 2 applies when the osteotomy is away from the CORA. While it's true that osteotomies are often performed away from the CORA for fixation reasons, the scenario here specifies the osteotomy isatthe CORA.

Question 2999

Topic: 2. Trauma

A 48-year-old patient with a severe bilateral varus deformity of the tibiae is undergoing Fixator-Assisted Nailing (FAN) for correction. After meticulous preoperative planning, strategic pin insertion, and osteotomy, the external fixator is locked, holding the limb in perfect corrected alignment. The surgeon then proceeds with reaming the intramedullary canal and inserting the intramedullary nail. What is the primary rationale for using a temporary external fixator in this scenario?

. To provide definitive, long-term fixation for the osteotomy, allowing for early weight-bearing.
. To allow for gradual, controlled correction of the deformity over several weeks post-operatively.
. To rigidly hold the limb in the perfectly corrected position, preventing displacement during the forces of intramedullary reaming and nail insertion.
. To stimulate bone healing at the osteotomy site through micromotion provided by the fixator.
. To facilitate the insertion of Poller screws into the medullary canal before nail insertion.

Correct Answer & Explanation

. To rigidly hold the limb in the perfectly corrected position, preventing displacement during the forces of intramedullary reaming and nail insertion.

Explanation

Correct Answer: CThe primary rationale for using a temporary external fixator in this scenario is to rigidly hold the limb in the perfectly corrected position, preventing displacement during the forces of intramedullary reaming and nail insertion. The text states: 'The physical forces involved in sequentially reaming an intramedullary canal and hammering a titanium nail can easily displace a perfectly corrected but unsecured osteotomy. A temporary external fixator acts as a rigid, unyielding external scaffold, locking the limb in the perfectly corrected position while the internal work is done.'Incorrect Options:A:The external fixator in FAN istemporaryand removed once the internal nail is locked, not for definitive, long-term fixation.B:While some external fixators are used for gradual correction, in FAN, the correction is achieved acutely and then held rigidly while the nail is inserted.D:The FAN technique aims for rigid stability during internal fixation, not micromotion, which would risk losing the acute correction.E:While Poller screws are often inserted with the fixator in place, the primary rationale for the fixator itself is to maintain alignment during the reaming and nailing process, not solely for Poller screw insertion.

Question 3000

Topic: Lower Extremity Trauma

During a Fixator-Assisted Nailing (FAN) procedure for a proximal tibial varus deformity, the surgeon considers inserting interference (Poller) screws. Which of the following statements accurately describes the purpose and optimal timing for inserting these screws in this context?

. Poller screws are inserted to provide primary fixation for the osteotomy, replacing the need for an intramedullary nail.
. Poller screws are used to artificially narrow the medullary canal, forcing the nail into the optimal trajectory and preventing translation, and are typically insertedbeforeremoving the external fixator.
. Poller screws are primarily used in distal femoral FAN to prevent rotational instability of the nail.
. Poller screws are insertedafterthe external fixator is removed to augment stability if the nail feels loose.
. Poller screws are used to create a hinge point for gradual correction of the deformity post-operatively.

Correct Answer & Explanation

. Poller screws are used to artificially narrow the medullary canal, forcing the nail into the optimal trajectory and preventing translation, and are typically insertedbeforeremoving the external fixator.

Explanation

Correct Answer: BPoller screws are used to artificially narrow the medullary canal, forcing the nail into the optimal trajectory and preventing translation, and are typically insertedbeforeremoving the external fixator. The text states: 'For added mechanical stability, interference screws (often called blocking or Poller screws) may be inserted to artificially narrow the medullary canal. This forces the nail into the optimal trajectory and prevents the nail from translating within the wide metaphyseal bone.' It also notes: 'Note:These interference screws are typically insertedbeforeremoving the external fixator to ensure the alignment isn't lost during screw placement.'Incorrect Options:A:Poller screws are foraugmentingstability and guiding the nail, not for primary fixation or replacing the nail.C:The text specifically states: 'This step is vastly more important for proximal tibial FAN than for distal femoral FAN due to the funnel shape of the proximal tibia.'D:Poller screws are typically insertedbeforeremoving the external fixator to maintain alignment during their placement.E:Poller screws are for rigid internal fixation, not for creating a hinge point for gradual correction.

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