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2. Trauma MCQs

Practice Set 463 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 9241

Topic: Upper Extremity Trauma

What is the most appropriate method to confirm proper screw length and avoid neurovascular injury or joint penetration when placing screws in a distal humerus locking plate?

. Using a depth gauge after drilling, without fluoroscopic assistance.
. Relying solely on tactile feel during screw insertion.
. Employing a combination of depth gauge measurements and intraoperative fluoroscopy in multiple planes.
. Placing screws bicortically regardless of surrounding anatomy.
. Using only monocortical screws to minimize risk.

Correct Answer & Explanation

. Employing a combination of depth gauge measurements and intraoperative fluoroscopy in multiple planes.

Explanation

In complex anatomical regions like the distal humerus, where neurovascular structures are abundant and articular penetration is a significant risk, a combination of precise depth gauge measurements and intraoperative fluoroscopy in multiple planes (AP, lateral, obliques) is essential to confirm appropriate screw length, bicortical purchase (if desired), and to ensure no penetration of the joint surface or compromise of neurovascular structures. Relying solely on depth gauge or tactile feel is insufficient. While monocortical screws may be used in specific scenarios, they are not the general rule, and bicortical screws are often desired for strength, requiring careful measurement.

Question 9242

Topic: 2. Trauma

Which of the following is a biomechanical characteristic of a 'tension band plate'?

. It provides absolute stability through interfragmentary compression across a transverse fracture.
. It is placed on the concave side of an eccentrically loaded bone to convert tensile forces into compression.
. It acts as a bridging device for comminuted fractures, promoting relative stability.
. It supports articular fragments against axial collapse.
. It functions primarily to resist torsional forces in the bone.

Correct Answer & Explanation

. It is placed on the concave side of an eccentrically loaded bone to convert tensile forces into compression.

Explanation

A tension band plate (or wire) is applied to the tension side (convex side during eccentric loading) of a bone, converting the tensile forces acting on that side into compressive forces across the fracture site. This stabilizes the fracture, often in simple transverse or short oblique patterns (e.g., olecranon, medial malleolus). It does not provide absolute stability through interfragmentary compression in the same way a DCP does, nor does it bridge comminution or primarily resist torsion. It's a specific application of mechanical principles to specific fracture patterns.

Question 9243

Topic: 2. Trauma

What is the primary goal of indirect reduction techniques when applying a plate, especially in comminuted diaphyseal fractures?

. To achieve anatomical reduction of every fracture fragment.
. To minimize soft tissue stripping and preserve periosteal blood supply.
. To provide absolute stability for primary bone healing.
. To facilitate the use of longer plates for greater rigidity.
. To ensure uniform compression across the fracture site.

Correct Answer & Explanation

. To minimize soft tissue stripping and preserve periosteal blood supply.

Explanation

Indirect reduction techniques (e.g., external fixators as 'joy-sticks,' ligamentotaxis, traction) are employed to restore overall limb length, alignment, and rotation without directly manipulating every fracture fragment. The primary goal is to minimize soft tissue stripping and preserve the periosteal blood supply to the comminuted fragments, thereby enhancing the biological environment for secondary bone healing. Anatomical reduction of every fragment is often impossible or undesirable in comminuted fractures. Absolute stability is typically not the goal, and uniform compression is difficult to achieve or maintain.

Question 9244

Topic: 2. Trauma

A 68-year-old female presents with a stable intertrochanteric fracture (AO/OTA 31-A1). She has osteoporosis. Which of the following IM nail features is most critical to prevent cut-out of the lag screw?

. A larger nail diameter.
. A longer nail to bypass the fracture zone.
. The use of a cephalomedullary nail with a short lag screw.
. Achieving tip-apex distance (TAD) of less than 25mm.
. The degree of femoral anteversion correction.

Correct Answer & Explanation

. Achieving tip-apex distance (TAD) of less than 25mm.

Explanation

The Tip-Apex Distance (TAD) is a crucial predictor of lag screw cut-out in intertrochanteric fractures treated with cephalomedullary nails. It represents the sum of the distance from the tip of the lag screw to the apex of the femoral head on both the anteroposterior (AP) and lateral radiographs, after accounting for magnification. A TAD less than 25mm (some sources cite 20mm) is strongly associated with a reduced risk of cut-out. While a larger nail diameter can provide general stability, it doesn't directly prevent cut-out of the lag screw. A longer nail is used for unstable fractures to bypass the isthmus and distal comminution. A short lag screw is often less stable than a well-placed long one within the head. Femoral anteversion correction is not directly related to cut-out risk in this context.

Question 9245

Topic: 2. Trauma

During the insertion of a tibial intramedullary nail, excessive valgus entry into the proximal tibia can lead to which of the following complications?

. Damage to the saphenous nerve.
. Varus malalignment of the fracture.
. Iatrogenic fracture of the medial tibial condyle.
. Fat embolism syndrome.
. Anterior knee pain due to patellar tendon impingement.

Correct Answer & Explanation

. Iatrogenic fracture of the medial tibial condyle.

Explanation

Excessive valgus entry (too medial) into the proximal tibia during IM nailing can lead to iatrogenic fracture of the medial tibial condyle due to reamer or nail impingement, particularly if the entry point is too close to the articular surface. A proper entry point should be just medial to the lateral tibial spine or at the junction of the medial and central thirds of the intercondylar eminence, allowing a straight shot down the medullary canal. Valgus entry would typically result in a more varus-aligned nail relative to the proximal tibia, potentially leading to varus malalignment of the fracture, not valgus. Saphenous nerve damage is more common with medial incisions, not specifically related to the entry point angle. Fat embolism is a general risk of IM nailing, not specific to valgus entry. Anterior knee pain is a common complication but not directly caused by the entry point angle itself, rather by the prominence of the nail or screw.

Question 9246

Topic: 2. Trauma

Which of the following statements regarding the 'nail dynamization' technique is correct?

. Dynamization is always performed at the fracture site.
. Dynamization typically involves removal of distal locking screws to promote compression.
. Dynamization is indicated for all femoral diaphyseal fractures treated with IM nails.
. Dynamization increases the torsional stability of the construct.
. Dynamization is performed to prevent nonunion in all cases.

Correct Answer & Explanation

. Dynamization typically involves removal of distal locking screws to promote compression.

Explanation

Dynamization typically involves the removal of either the proximal or, more commonly, the distal locking screws to allow controlled axial micromotion and compression at the fracture site. This is done in an attempt to stimulate callus formation and union, particularly in cases of delayed union or hypertrophic nonunion where the fracture is mechanically stable but not healing. It is not always performed at the fracture site, as the screws are typically removed away from the fracture. It is not indicated for all fractures, as unstable or comminuted fractures initially require static stability. Dynamization decreases, rather than increases, torsional stability. While it aims to promote union, it is not a guaranteed prevention for all nonunions and is typically reserved for specific situations.

Question 9247

Topic: 2. Trauma
In the context of intramedullary nailing, which type of fracture typically benefits most from reamed nailing over unreamed nailing, considering union rates?
. Open Gustilo-Anderson Type IIIB tibia fractures.
. Severely comminuted femoral diaphyseal fractures.
. Unstable intertrochanteric hip fractures.
. Segmental tibia fractures with significant soft tissue injury.
. Humeral diaphyseal fractures with associated radial nerve palsy.

Correct Answer & Explanation

. Severely comminuted femoral diaphyseal fractures.

Explanation

Severely comminuted femoral diaphyseal fractures (e.g., AO/OTA 32-C3) generally benefit most from reamed nailing. Reaming allows for the insertion of a larger diameter nail, which provides superior biomechanical stability (bending and torsional stiffness). This enhanced stability is particularly critical in highly comminuted fractures where the bone's inherent stability is compromised. This often leads to higher union rates and reduced rates of implant failure compared to unreamed nailing in such complex fractures. Open fractures, especially Type IIIB, are often treated with unreamed nails due to infection risk. Intertrochanteric fractures are treated with cephalomedullary nails, where reaming is typically less extensive or different. Segmental tibia fractures with significant soft tissue are challenging, and unreamed or staged approaches are often considered. Humeral fractures generally respond well to standard IM nailing, but the radial nerve palsy doesn't dictate reaming versus unreaming directly.

Question 9248

Topic: Lower Extremity Trauma

Which factor is most predictive of anterior knee pain following tibial intramedullary nailing?

. The use of a quadriceps-sparing approach.
. The prominence of the proximal end of the nail above the tibial plateau.
. The duration of immobilization post-operatively.
. The length of the intramedullary nail.
. The patient's age and activity level.

Correct Answer & Explanation

. The prominence of the proximal end of the nail above the tibial plateau.

Explanation

The most predictive factor for anterior knee pain following tibial intramedullary nailing is the prominence of the proximal end of the nail above the tibial plateau. If the nail is inserted too proud, it can impinge on the patellar tendon, quadriceps tendon, or prepatellar bursa, leading to persistent anterior knee pain. While a quadriceps-sparing approach aims to minimize soft tissue disruption, nail prominence is a direct mechanical irritant. Duration of immobilization and nail length are less direct causes. Patient age and activity level can influence symptoms but are not the primary direct cause of this specific complication.

Question 9249

Topic: 2. Trauma

What is the primary mechanism by which intramedullary nailing promotes fracture healing?

. Complete rigid stabilization to prevent any micromotion.
. Direct bone-to-bone contact through interfragmentary compression.
. Relative stability, preserving soft tissue envelope and periosteal blood supply.
. Induction of endochondral ossification through absolute stability.
. Promotion of primary bone healing without callus formation.

Correct Answer & Explanation

. Relative stability, preserving soft tissue envelope and periosteal blood supply.

Explanation

Intramedullary nailing primarily promotes fracture healing through the principle of relative stability. By splinting the fracture from within the medullary canal, it provides sufficient stability to allow for controlled micromotion, which stimulates callus formation (secondary bone healing). Crucially, IM nailing is a load-sharing device and is minimally invasive, preserving the critical soft tissue envelope and periosteal blood supply, which are vital for bone healing. It does not provide absolute rigid stability (like lag screw fixation aiming for primary healing) or direct interfragmentary compression in the same way plates do. While some compression can occur with dynamization, it's not the primary mechanism of stabilization for all IM nails.

Question 9250

Topic: 2. Trauma

When treating a reverse obliquity intertrochanteric fracture (AO/OTA 31-A3) with an intramedullary nail, which biomechanical concern is paramount?

. The risk of implant cut-out due to varus forces.
. The need for a short cephalomedullary nail to maintain length.
. The increased bending stress on the nail at the subtrochanteric region.
. The potential for medial displacement of the distal fragment.
. The importance of preventing femoral head rotation.

Correct Answer & Explanation

. The potential for medial displacement of the distal fragment.

Explanation

Reverse obliquity fractures are characterized by a fracture line extending from the lesser trochanter proximally to the greater trochanter distally. This configuration is inherently unstable and prone to medial displacement of the distal fragment, especially with a laterally based implant (like a traditional plate). Long cephalomedullary nails are generally preferred because they resist this medialization and provide greater stability against varus collapse. The risk of cut-out is also present but often exacerbated by the medial displacement if not controlled. A short nail would not be sufficient to control the distal fragment. Increased bending stress is a general concern for highly unstable fractures but not the specific paramount biomechanical concern for reverse obliquity. Preventing femoral head rotation is important for all hip fractures, but medial displacement is the unique challenge for reverse obliquity.

Question 9251

Topic: 2. Trauma
Which clinical scenario is generally considered an absolute contraindication for intramedullary nailing of a long bone fracture?
. Polytrauma patient with an Injury Severity Score (ISS) of 25.
. Extensive local soft tissue infection at the planned incision site.
. Significant osteoporosis (T-score -3.5).
. Prior history of compartment syndrome in the affected limb.
. Open fracture with a Gustilo-Anderson Type IIIA classification.

Correct Answer & Explanation

. Extensive local soft tissue infection at the planned incision site.

Explanation

Extensive local soft tissue infection at the planned incision site is an absolute contraindication for intramedullary nailing. Introducing an implant through an infected field significantly increases the risk of deep infection, osteomyelitis, and nonunion. Polytrauma patients with high ISS are often candidates for IM nailing, sometimes after damage control. Significant osteoporosis makes fixation challenging but isn't an absolute contraindication, often requiring specific nail designs (e.g., cemented, augments). A history of compartment syndrome does not preclude IM nailing of a new fracture. Open Gustilo-Anderson Type IIIA fractures are often treated with unreamed IM nails after appropriate debridement.

Question 9252

Topic: 2. Trauma

During closed reduction and intramedullary nailing of a femoral shaft fracture, what radiographic view is most critical for assessing rotational alignment?

. Anteroposterior (AP) view of the hip and knee.
. Lateral view of the hip and knee.
. True lateral view of the proximal femur.
. Comparison of lesser trochanter profile on AP hip views.
. Oblique views of the fracture site.

Correct Answer & Explanation

. Comparison of lesser trochanter profile on AP hip views.

Explanation

To assess rotational alignment during femoral intramedullary nailing, comparing the lesser trochanter profile on AP hip views is the most practical and commonly used intraoperative method. In a neutral rotation, the lesser trochanter should be faintly visible or not visible. Increased internal rotation makes it disappear, while external rotation makes it more prominent. The AP and lateral views help with length and angular alignment but are less sensitive for rotation. True lateral views of the proximal femur are also useful but less standardized for assessing rotation intraoperatively than the lesser trochanter profile. Oblique views primarily help visualize the fracture pattern.

Question 9253

Topic: 2. Trauma

Which of the following is a recognized advantage of using an intramedullary nail over plate osteosynthesis for a mid-shaft clavicle fracture?

. Stronger biomechanical construct against bending forces.
. Reduced risk of neurovascular injury due to percutaneous approach.
. Superior rates of union and faster return to activity.
. Better cosmetic outcome due to smaller incisions.
. Ability to correct complex three-dimensional deformities more effectively.

Correct Answer & Explanation

. Better cosmetic outcome due to smaller incisions.

Explanation

For mid-shaft clavicle fractures, intramedullary nailing can offer a better cosmetic outcome due to smaller incisions, as the nail is inserted percutaneously from either end. While IM nails provide good stability, plates often provide a stronger biomechanical construct, especially against bending. Union rates and return to activity are comparable between the two methods, with some studies showing slight advantages for plates in specific contexts. Neurovascular injury risk is still present with IM nails, especially if not carefully placed. Complex three-dimensional deformities are often better managed with open reduction and plate fixation, which allows direct visualization and precise fragment manipulation.

Question 9254

Topic: 2. Trauma

What is the major long-term complication associated with proximal tibial intramedullary nailing that is often directly related to the entry point and nail design?

. Deep vein thrombosis.
. Compartment syndrome.
. Anterior knee pain.
. Peroneal nerve palsy.
. Infection.

Correct Answer & Explanation

. Anterior knee pain.

Explanation

Anterior knee pain is a well-recognized and common long-term complication following proximal tibial intramedullary nailing. It is frequently attributed to irritation of the patellar tendon or quadriceps tendon by a prominent nail or entry portal hardware, or damage to the infrapatellar branch of the saphenous nerve. A proper entry point (just medial to the lateral tibial spine or at the junction of the medial and central thirds of the intercondylar eminence) and ensuring the nail is seated flush or slightly subcortical are crucial to minimize this risk. DVT, compartment syndrome, and peroneal nerve palsy are potential complications but less directly related to the entry point/nail design and typically occur acutely or subacutely. Infection is a risk for any surgery but not uniquely or predominantly linked to the entry point in causing long-term pain.

Question 9255

Topic: 2. Trauma

A 28-year-old male presents with a spiral fracture of the distal third of the tibia. Which type of locking screw configuration is most appropriate to resist the deforming forces in this specific fracture pattern?

. Dynamic locking proximally and distally.
. Static locking proximally and dynamically distally.
. Static locking proximally and distally.
. Lag screw fixation across the fracture site.
. No locking screws, relying on press-fit only.

Correct Answer & Explanation

. Static locking proximally and distally.

Explanation

A spiral fracture of the distal third of the tibia is inherently rotationally unstable. Static locking (i.e., locking screws both proximally and distally) is essential to control both axial shortening and, critically, rotational instability. Dynamic locking, by allowing some axial motion, would be insufficient to control rotation in a spiral fracture. Lag screw fixation is not typically applicable for intramedullary nails across a diaphyseal fracture site in the same way it is for plates. Relying on press-fit alone would lead to significant instability and malunion.

Question 9256

Topic: 2. Trauma

In the setting of a traumatic femoral shaft fracture, which intraoperative technique is most effective in preventing varus malalignment when using an antegrade IM nail?

. Placing the entry point as medially as possible on the greater trochanter.
. Ensuring the guidewire is centrally located in both AP and lateral views throughout the length of the femur.
. Applying persistent valgus stress during reaming and nail insertion.
. Using a small diameter nail to allow for easy manipulation.
. Relying solely on external rotation of the distal fragment.

Correct Answer & Explanation

. Ensuring the guidewire is centrally located in both AP and lateral views throughout the length of the femur.

Explanation

Varus malalignment is a common issue with antegrade femoral IM nailing, often caused by a laterally placed entry point on the greater trochanter. To prevent this, it is crucial to ensure the guidewire is centrally located in both the AP and lateral views throughout the length of the femur. This helps to ensure the nail follows the anatomical axis and avoids impingement, which can force the distal fragment into varus. A medial entry point risks iatrogenic fracture of the greater trochanter or even avascular necrosis if too medial in the piriformis. Applying valgus stress can help correct varus but isn't as fundamental as proper guidewire placement. A small nail would offer less stability. Relying solely on external rotation doesn't address angular alignment.

Question 9257

Topic: 2. Trauma

For a distal tibia fracture extending into the metaphysis (AO/OTA 43-A1), which characteristic of an intramedullary nail is most beneficial?

. A straight nail design for optimal diaphyseal fit.
. A long, large-diameter nail for maximal stability.
. Multiplanar distal locking options to capture small distal fragments.
. Proximal dynamic locking to allow early weight-bearing.
. A reaming protocol that extends beyond the metaphyseal-diaphyseal junction.

Correct Answer & Explanation

. Multiplanar distal locking options to capture small distal fragments.

Explanation

Distal tibia fractures, especially those extending into the metaphysis, present a challenge due to the wider canal and often shorter distal fragment. Multiplanar distal locking options (e.g., oblique and transverse screws) are most beneficial as they allow for better capture and stabilization of the short, wide, and often comminuted distal fragment, providing enhanced stability against angular and rotational forces. A straight nail design might not fit the distal flare. A long, large-diameter nail is not always possible in the distal fragment. Proximal dynamic locking is less critical than robust distal fixation for these fractures. Reaming extending beyond the junction is part of standard reaming but not the most critical feature compared to the locking options for distal fractures.

Question 9258

Topic: 2. Trauma

What is the primary reason for using a blocking screw (poller screw) during intramedullary nailing?

. To provide absolute stability at the fracture site.
. To increase the biomechanical strength of the nail itself.
. To guide the nail into a desired position and prevent malalignment.
. To facilitate dynamization by blocking one set of locking screws.
. To prevent nail propagation into the articular surface.

Correct Answer & Explanation

. To guide the nail into a desired position and prevent malalignment.

Explanation

Blocking screws (poller screws) are used to 'block' or guide the intramedullary nail into a desired position within the canal, primarily to prevent malalignment (e.g., varus/valgus, procurvatum/recurvatum) in metaphysial or highly comminuted diaphyseal fractures. By strategically placing screws in the wider part of the canal, they effectively narrow the canal and force the nail into a central or desired position, improving reduction and alignment. They do not provide absolute stability themselves, nor do they increase the nail's strength or directly facilitate dynamization. While they can help prevent errant nail trajectories, their primary role is alignment guidance.

Question 9259

Topic: 2. Trauma

In the context of fracture healing, how does intramedullary nailing typically compare to plating regarding the type of bone healing?

. IM nailing primarily promotes primary bone healing, while plating promotes secondary bone healing.
. IM nailing primarily promotes secondary bone healing, while plating can promote either primary or secondary.
. Both IM nailing and plating exclusively promote primary bone healing.
. Both IM nailing and plating exclusively promote secondary bone healing.
. IM nailing inhibits periosteal healing, while plating enhances it.

Correct Answer & Explanation

. IM nailing primarily promotes secondary bone healing, while plating can promote either primary or secondary.

Explanation

Intramedullary nailing primarily promotes secondary bone healing (indirect healing) characterized by callus formation. It provides relative stability, allowing controlled micromotion at the fracture site, which is conducive to endochondral ossification. Plate osteosynthesis can promote either primary (direct) bone healing if absolute stability and interfragmentary compression are achieved (e.g., lag screw fixation of simple fractures) or secondary bone healing if used in a bridging fashion for comminuted fractures, providing relative stability. Therefore, IM nailing is generally associated with secondary healing, while plating has a broader spectrum depending on the technique.

Question 9260

Topic: 2. Trauma

A 75-year-old patient with an unstable proximal humerus fracture (AO/OTA 11-A3) is considered for IM nailing. What is a specific challenge of IM nailing in this type of fracture compared to diaphyseal fractures?

. Difficulty in achieving length stability due to muscle pull.
. High risk of fat embolism due to cancellous bone reaming.
. Maintaining reduction of the articular fragments.
. Increased risk of radial nerve injury with distal locking.
. Poor bone quality preventing adequate screw purchase.

Correct Answer & Explanation

. Maintaining reduction of the articular fragments.

Explanation

Unstable proximal humerus fractures, particularly those with articular involvement or severe comminution (like 11-A3), pose a significant challenge for IM nailing primarily due to the difficulty in maintaining reduction of the articular fragments. IM nails are often better suited for diaphyseal fractures, relying on the intramedullary fit and locking screws. In the proximal humerus, achieving stable fixation of the humeral head fragments, especially in osteoporotic bone, can be challenging, leading to issues like screw cut-out or collapse. While poor bone quality (osteoporosis) is often present and affects screw purchase, the primary challenge is the anatomical complexity of maintaining the reduction of the articular segment. Radial nerve injury is a distal complication. Fat embolism risk is generally lower than with femoral nailing. Length is usually less of an issue than angular or rotational stability in the proximal humerus.

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