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2. Trauma MCQs

Practice Set 252 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 5021

Topic: 2. Trauma
A 70-year-old female on long-term alendronate therapy presents with a diaphyseal femur fracture after a minor fall. According to the ASBMR Task Force criteria, which of the following is a required major feature to diagnose an atypical femoral fracture?
. Bilateral fractures or prodromal pain
. Comminuted fracture pattern
. Delayed fracture healing
. Fracture line originates at the lateral cortex and is strictly transverse or short oblique
. Concurrent use of glucocorticoids

Correct Answer & Explanation

. Fracture line originates at the lateral cortex and is strictly transverse or short oblique

Explanation

According to the ASBMR criteria, major features of atypical femoral fractures (AFFs) include: location anywhere from distal to the lesser trochanter to proximal to the supracondylar flare, associated with minimal/no trauma, transverse or short oblique configuration, noncomminuted or minimally comminuted, complete fractures extending through both cortices with a medial spike, and the fracture line MUST originate at the lateral cortex.

Question 5022

Topic: 2. Trauma

A 78-year-old female undergoes fixation of an unstable intertrochanteric femur fracture with a sliding hip screw (DHS). Which of the following radiographic parameters is most predictive of hardware cutout and mechanical failure?

. Pauwels angle > 50 degrees
. Tip-Apex Distance (TAD) > 25 mm
. Posterior sag of the distal fragment
. Lateral wall thickness > 21 mm
. Loss of the lesser trochanter

Correct Answer & Explanation

. Tip-Apex Distance (TAD) > 25 mm

Explanation

Baumgaertner et al. established that a Tip-Apex Distance (TAD) greater than 25 mm on AP and lateral radiographs is the strongest independent predictor of lag screw cutout in both sliding hip screws and cephalomedullary nails for intertrochanteric fractures.

Question 5023

Topic: 2. Trauma

A 30-year-old male polytrauma patient sustains an ipsilateral midshaft femur fracture and a midshaft tibia fracture (floating knee). He is hemodynamically stable but has bilateral pulmonary contusions. The multidisciplinary team decides on Damage Control Orthopedics (DCO) rather than Early Total Care (ETC). Which of the following laboratory values most strongly supports the decision for DCO over ETC?

. Serum lactate > 2.5 mmol/L and elevated IL-6
. Hemoglobin of 9.0 g/dL
. Platelet count of 150,000/uL
. Base deficit of -1.5
. Fibrinogen of 300 mg/dL

Correct Answer & Explanation

. Serum lactate > 2.5 mmol/L and elevated IL-6

Explanation

In polytrauma patients, markers of physiologic exhaustion and systemic inflammatory response dictate the choice between ETC and DCO. A serum lactate > 2.5 mmol/L, base deficit > 2.0 (more negative than -2.0), or markedly elevated inflammatory markers (like IL-6) indicate a borderline or unstable patient who is at high risk for 'second hit' phenomena (like ARDS) if subjected to prolonged ETC procedures like bilateral reamed intramedullary nailing.

Question 5024

Topic: 2. Trauma

An 82-year-old female presents with an intertrochanteric femur fracture. On the preoperative anteroposterior radiograph, the lateral wall thickness is measured at 18 mm. What is the clinical implication of this measurement when planning surgical fixation?

. It is safe to use a sliding hip screw (DHS) as the primary fixation device.
. There is a high risk of iatrogenic lateral wall fracture if a sliding hip screw is used; a cephalomedullary nail is preferred.
. It indicates an impending atypical femur fracture requiring prolonged bisphosphonate cessation.
. It necessitates prophylactic cerclage wiring of the subtrochanteric region prior to passing a reamer.

Correct Answer & Explanation

. There is a high risk of iatrogenic lateral wall fracture if a sliding hip screw is used; a cephalomedullary nail is preferred.

Explanation

The lateral wall thickness is a critical predictor of postoperative instability in intertrochanteric fractures. Hsu et al. demonstrated that a lateral wall thickness of less than 20.5 mm is an independent predictor for lateral wall fracture when a sliding hip screw (DHS) is used. When the lateral wall fractures, the fracture effectively becomes a reverse obliquity equivalent, leading to medial medialization of the shaft and fixation failure. Therefore, cephalomedullary nailing is the preferred implant for fractures with an intact but thin (< 20.5 mm) lateral wall.

Question 5025

Topic: 2. Trauma

A 35-year-old male involved in a motorcycle collision sustains a high-energy distal femur fracture. CT scan reveals a coronal shear fracture of the lateral femoral condyle (Hoffa fracture). Regarding the biomechanical fixation of this specific fracture fragment, which of the following statements is true?

. Anterior-to-posterior (AP) lag screws are biomechanically superior to posterior-to-anterior (PA) screws.
. Posterior-to-anterior (PA) lag screws provide superior compression and pull-out strength compared to AP screws.
. A lateral locking plate alone without independent lag screws provides the highest construct stiffness.
. Countersinking the screw head on the articular surface decreases the compressive force at the fracture site.

Correct Answer & Explanation

. Posterior-to-anterior (PA) lag screws provide superior compression and pull-out strength compared to AP screws.

Explanation

A Hoffa fracture is a coronal plane fracture of the distal femur, most commonly involving the lateral condyle. Biomechanical studies have demonstrated that posterior-to-anterior (PA) directed lag screws placed perpendicular to the fracture plane provide superior pull-out strength and compression compared to anterior-to-posterior (AP) screws. This is due to the denser bone in the posterior condyle allowing for better thread purchase, whereas AP screws often engage the less dense anterior metaphysis.

Question 5026

Topic: 2. Trauma

A 45-year-old male sustains a high-energy tibial plateau fracture. CT imaging identifies a large posteromedial coronal split fragment. What is the optimal surgical approach and fixation strategy for this specific fragment?

. Anterolateral approach with a single lateral locked plate utilizing long screws.
. Posteromedial approach with an anti-glide or buttress plate.
. Anterior midline approach with dual medial and lateral plating.
. Arthroscopically assisted percutaneous AP lag screw fixation.

Correct Answer & Explanation

. Posteromedial approach with an anti-glide or buttress plate.

Explanation

A posteromedial shear fragment in a tibial plateau fracture (often a Schatzker IV or component of Schatzker V/VI) tends to displace distally and posteriorly. Lateral locked plating with long screws directed medially is insufficient to maintain reduction of a posteromedial coronal split due to the lack of direct buttressing and the trajectory of the screws (which often parallel the fracture line). The optimal treatment is a direct posteromedial approach with the application of an anti-glide or buttress plate to mechanically counteract the displacing forces.

Question 5027

Topic: 2. Trauma
A 28-year-old male presents with a high-energy Pauwels type III (vertical shear) femoral neck fracture. Which of the following internal fixation constructs provides the greatest biomechanical stability for this fracture pattern?
. Three parallel cancellous screws placed in an inverted triangle configuration.
. A sliding hip screw (DHS) supplemented with a derotational cancellous screw.
. A fully threaded proximal femoral locking plate.
. Two parallel fully threaded cortical screws.

Correct Answer & Explanation

. A sliding hip screw (DHS) supplemented with a derotational cancellous screw.

Explanation

Pauwels type III femoral neck fractures have a vertical fracture line (angle > 50 degrees), which subjects the fracture site to high shear forces rather than compressive forces. Multiple cancellous screws (length-stable but shear-weak) have a high failure rate in this pattern. Biomechanical studies have shown that a fixed-angle device, such as a sliding hip screw (DHS), supplemented with an anti-rotation screw, provides superior stability and resists the varus collapse and shear forces much better than multiple cancellous screws.

Question 5028

Topic: 2. Trauma

When utilizing a sliding hip screw to stabilize an intertrochanteric femur fracture, minimizing the Tip-Apex Distance (TAD) is critical. Which of the following statements regarding the TAD rule is correct?

. It is measured only on the intraoperative anteroposterior radiograph.
. A TAD greater than 25 mm is associated with a significantly increased risk of implant cut-out.
. The TAD is defined as the distance from the screw tip to the articular surface of the acetabulum.
. A lower TAD implies the screw is placed far from the subchondral bone, reducing the risk of joint penetration.

Correct Answer & Explanation

. A TAD greater than 25 mm is associated with a significantly increased risk of implant cut-out.

Explanation

The Tip-Apex Distance (TAD), described by Baumgaertner, is the sum of the distance from the tip of the lag screw to the apex of the femoral head on both the AP and lateral radiographs. A TAD of less than 25 mm has been strongly correlated with a successful outcome, whereas a TAD greater than 25 mm is associated with a significantly increased risk of screw cut-out. The goal is deep, central placement of the screw in the femoral head.

Question 5029

Topic: 2. Trauma

A 72-year-old female who underwent a posterior stabilized (PS) total knee arthroplasty 10 years ago sustains a displaced distal femur fracture 4 cm superior to the femoral component flange. Radiographs show the component remains well-fixed. The original operative note confirms the use of a standard closed-box PS femoral component. What is the most appropriate fixation strategy?

. Retrograde intramedullary nailing.
. Open reduction and internal fixation with a lateral locked plate.
. Revision to a distal femoral replacement.
. Application of an Ilizarov fine-wire circular frame.

Correct Answer & Explanation

. Open reduction and internal fixation with a lateral locked plate.

Explanation

This is a Su Type II (or Lewis-Rorabeck Type II) periprosthetic distal femur fracture, defined as a displaced fracture proximal to a well-fixed component. While both retrograde intramedullary nailing and lateral locked plating are valid options for periprosthetic fractures, a closed-box design of a posterior stabilized (PS) femoral component physically blocks the entry point in the intercondylar notch, precluding the use of a retrograde nail. Therefore, lateral locked plating is the procedure of choice.

Question 5030

Topic: 2. Trauma

A 40-year-old male sustains a proximal third subtrochanteric femur fracture. During closed reduction maneuvers prior to intramedullary nailing, the proximal fracture fragment is noted to be severely flexed, abducted, and externally rotated. Which muscle group is primarily responsible for the external rotation of the proximal fragment?

. Iliopsoas
. Gluteus medius and minimus
. Short external rotators (e.g., piriformis, superior/inferior gemellus, obturator internus/externus)
. Tensor fasciae latae
. Adductor magnus

Correct Answer & Explanation

. Iliopsoas

Explanation

In subtrochanteric femur fractures, the classic deforming forces on the proximal fragment include flexion (via the iliopsoas attaching to the lesser trochanter), abduction (via the gluteus medius and minimus attaching to the greater trochanter), and external rotation (via the short external rotators inserting into the greater trochanteric region). The distal fragment is typically adducted (adductors) and translated proximally (hamstrings and quadriceps).

Question 5031

Topic: 2. Trauma
A 12-year-old boy sustains a completely displaced tibial eminence fracture (Meyers and McKeever Type III) while skiing. During an arthroscopically assisted reduction and internal fixation, the surgeon finds the fracture cannot be anatomically reduced despite clearing the fracture hematoma. Which anatomical structure is most commonly entrapped, blocking reduction?
. Anterior horn of the medial meniscus
. Posterior horn of the lateral meniscus
. Infrapatellar plica
. Ligament of Wrisberg
. Medial collateral ligament

Correct Answer & Explanation

. Anterior horn of the medial meniscus

Explanation

Tibial eminence avulsion fractures are the pediatric equivalent of an ACL tear. When they are completely displaced (Type III), closed reduction is often unsuccessful due to soft tissue interposition. The most common structures that become entrapped under the fracture fragment and block reduction are the anterior horn of the medial meniscus and the intermeniscal (transverse) ligament. These must be extracted anatomically (often arthroscopically) to allow the fragment to seat in its bed.

Question 5032

Topic: 2. Trauma

A 22-year-old male is admitted after a high-speed motor vehicle collision with an ipsilateral midshaft femur and midshaft tibia fracture (Fraser Type I floating knee). He is hemodynamically stable without head or chest trauma. To minimize the risk of acute respiratory distress syndrome (ARDS) and fat embolism syndrome, what is the most appropriate management sequence?

. Fix the tibia first to provide a stable base, followed by delayed femur fixation.
. Early intramedullary nailing of both the femur and tibia within 24 hours.
. Temporize both fractures with spanning external fixation and perform definitive fixation at 7-10 days.
. Fix the femur with a dynamic compression plate to avoid intramedullary canal pressurization.

Correct Answer & Explanation

. Early intramedullary nailing of both the femur and tibia within 24 hours.

Explanation

In a hemodynamically stable polytrauma patient (without significant traumatic brain injury or severe lung contusions precluding early total care), early definitive intramedullary nailing of long bone fractures within 24 hours is the standard of care. Early total care (ETC) stabilizes the fractures, decreases the systemic inflammatory response, permits early mobilization, and has been proven to significantly lower the incidence of ARDS, fat embolism syndrome, and pulmonary complications compared to delayed fixation.

Question 5033

Topic: 2. Trauma

A 55-year-old male presents with a completely displaced basicervical femoral neck fracture. Which of the following statements regarding the biomechanics and clinical behavior of this specific fracture pattern is true?

. It behaves mechanically similarly to a standard intertrochanteric fracture and requires identical fixation.
. It has a higher rate of implant failure, cut-out, and nonunion compared to standard intertrochanteric fractures.
. Multiple cancellous screws are the preferred fixation method as it is strictly an intracapsular fracture.
. The fracture relies entirely on endosteal callus for healing.

Correct Answer & Explanation

. It has a higher rate of implant failure, cut-out, and nonunion compared to standard intertrochanteric fractures.

Explanation

Basicervical femoral neck fractures occur at the junction of the femoral neck and the intertrochanteric line. Although technically extracapsular, they lack the broad cancellous bony interdigitation found in standard intertrochanteric fractures. As a result, they are highly mechanically unstable, particularly in rotation, and behave uniquely. They carry a significantly higher risk of implant failure, screw cut-out, and nonunion compared to standard IT fractures. Fixation requires a rigid, rotationally stable device such as a cephalomedullary nail or a DHS supplemented with a derotation screw.

Question 5034

Topic: 2. Trauma

A 35-year-old female undergoes intramedullary nailing of a midshaft tibia fracture utilizing a suprapatellar approach. During the procedure, a protective trocar and cannula system is used. If this cannula is inadequately seated or the knee is positioned incorrectly, which intra-articular structure is at highest risk of iatrogenic damage?

. Anterior cruciate ligament
. Trochlear articular cartilage
. Posterior cruciate ligament
. Medial patellofemoral ligament
. Coronary ligaments

Correct Answer & Explanation

. Trochlear articular cartilage

Explanation

The suprapatellar approach to tibial nailing involves passing the instruments and nail through the patellofemoral joint. A specialized cannula/trocar system must be properly seated in the intercondylar notch to protect the joint surfaces. The structure at greatest risk of iatrogenic damage from reamers or the nail itself, particularly if the knee is not adequately flexed (usually 10-20 degrees is ideal) or the cannula slips, is the articular cartilage of the femoral trochlea or the deep surface of the patella.

Question 5035

Topic: 2. Trauma

A 42-year-old male undergoes tension band wiring for a transverse mid-pole patella fracture. For the tension band principle to function effectively during active knee extension and weight-bearing flexion, it dynamically converts tensile forces into compressive forces at the articular surface. The primary tensile forces being neutralized are generated on which anatomic aspect of the patella?

. The anterior cortical surface
. The posterior articular surface
. The medial and lateral retinacular expanses
. The central intramedullary axis

Correct Answer & Explanation

. The anterior cortical surface

Explanation

The biomechanical principle of a tension band is to place the fixation on the tension side of a bone subject to eccentric loading. In the patella, the pull of the quadriceps tendon and patellar tendon creates tensile forces on the anterior cortical surface during flexion. By placing the wire construct on the anterior surface, these tensile forces are converted into compressive forces at the posterior (articular) surface, promoting stability and healing.

Question 5036

Topic: 2. Trauma

A 75-year-old female sustains a highly comminuted distal femur fracture, which is stabilized using a modern lateral locking plate. To decrease the stiffness of the construct and promote secondary bone healing via callus formation across the comminuted segment, what technical modification should the surgeon employ?

. Fill every screw hole in the plate to maximize the bone-implant interface.
. Increase the working length of the construct by omitting screws adjacent to the fracture site.
. Decrease the plate span ratio to less than 2.0.
. Utilize a stainless steel plate rather than a titanium alloy plate.

Correct Answer & Explanation

. Increase the working length of the construct by omitting screws adjacent to the fracture site.

Explanation

In bridge plating of comminuted fractures with locking plates, overly stiff constructs suppress the micromotion necessary for secondary bone healing (callus formation), leading to nonunion or implant failure. The 'working length' is the distance between the two innermost screws on either side of the fracture. Increasing the working length by leaving holes empty adjacent to the fracture decreases construct stiffness and permits appropriate micromotion. A plate span ratio > 2-3 is recommended in comminuted fractures.

Question 5037

Topic: 2. Trauma

A 4-year-old boy sustains a completely displaced midshaft femur fracture. The orthopedic surgeon treats the fracture with immediate spica casting and accepts a reduction with 1.5 cm of overriding (shortening). What is the primary physiologic rationale for accepting this overriding in this age group?

. It mechanically compensates for expected late varus drift within the cast.
. It prevents hypertrophic nonunion by maximizing the diaphyseal cross-sectional contact area.
. It compensates for the post-traumatic transient overgrowth phenomenon of the fractured femur.
. It relieves tension on the neurovascular bundle, decreasing the risk of compartment syndrome.

Correct Answer & Explanation

. It compensates for the post-traumatic transient overgrowth phenomenon of the fractured femur.

Explanation

In children between the ages of 2 and 10 years, a diaphyseal femur fracture stimulates increased blood flow and physial activity, leading to a phenomenon known as transient overgrowth. The fractured femur will typically overgrow by 1 to 2 cm over the following 1 to 2 years. Therefore, it is standard practice to accept (and actually aim for) 1 to 2 cm of bayonet apposition (shortening) during initial reduction to result in equal leg lengths at skeletal maturity.

Question 5038

Topic: 2. Trauma

A 28-year-old male arrives at the emergency department with a traumatic posterior hip dislocation following a motor vehicle collision. Which of the following factors is most strongly associated with an increased risk of developing avascular necrosis (AVN) of the femoral head in this patient?

. Time from injury to concentric reduction exceeding 6 hours.
. The presence of a concomitant anterior acetabular wall fracture.
. An associated ipsilateral femoral shaft fracture.
. Administration of regional anesthesia rather than general anesthesia prior to reduction.

Correct Answer & Explanation

. Time from injury to concentric reduction exceeding 6 hours.

Explanation

The risk of avascular necrosis (AVN) following a traumatic hip dislocation is directly correlated with the duration the hip remains dislocated. Prolonged dislocation places sustained tension on the retinacular vessels (branches of the medial circumflex femoral artery) and increases intracapsular pressure, leading to ischemia. Evidence strongly supports that reduction within 6 hours significantly decreases the risk of AVN. The other options are not primary drivers of AVN compared to the ischemic time.

Question 5039

Topic: 2. Trauma

A 35-year-old female sustains a high-speed motor vehicle collision and is diagnosed with an isolated coronal shear fracture of the lateral femoral condyle (Hoffa fracture). During open reduction and internal fixation, what is the biomechanically optimal direction for lag screw placement to achieve maximum stability?

. Anterior-to-posterior (AP) lag screws
. Posterior-to-anterior (PA) lag screws
. Medial-to-lateral lag screws
. Lateral-to-medial lag screws
. Inferior-to-superior lag screws

Correct Answer & Explanation

. Posterior-to-anterior (PA) lag screws

Explanation

Posterior-to-anterior (PA) lag screws are biomechanically superior for Hoffa fractures. They are directed perpendicular to the fracture plane and maximize thread purchase in the denser anterior cortical bone of the metaphysis, providing significantly greater pull-out strength compared to AP screws.

Question 5040

Topic: 2. Trauma

A 45-year-old male sustains a high-energy Schatzker IV tibial plateau fracture. Lateral radiographs demonstrate a 'double contour' sign. What is the optimal surgical approach and fixation strategy for this specific fracture pattern?

. Anterolateral approach with a lateral locking plate
. Medial approach with a bridging plate
. Posteromedial approach with anti-glide plating
. Arthroscopically assisted percutaneous screw fixation
. Anterior midline approach with dual medial and lateral plating

Correct Answer & Explanation

. Posteromedial approach with anti-glide plating

Explanation

The 'double contour' sign on a lateral radiograph indicates a posteromedial shear fragment in a tibial plateau fracture. The optimal mechanical fixation for a posteromedial shear fracture is a posteromedial approach with an anti-glide plate to buttress the fragment and neutralize vertical shear forces.

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