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2. Trauma MCQs

Practice Set 464 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 9261

Topic: 2. Trauma

What is the primary role of the antirotation screw in a cephalomedullary nail system for proximal femoral fractures?

. To provide additional axial stability against shortening.
. To augment the primary lag screw's fixation in the femoral head.
. To prevent rotation of the femoral head fragment relative to the nail.
. To achieve interfragmentary compression across the fracture site.
. To act as a blocking screw for nail insertion.

Correct Answer & Explanation

. To prevent rotation of the femoral head fragment relative to the nail.

Explanation

The primary role of the antirotation screw (or second lag screw/helical blade) in a cephalomedullary nail system is to prevent rotation of the femoral head fragment relative to the nail. This is crucial for maintaining the reduction of the fracture and preventing rotational malunion, especially in unstable intertrochanteric or subtrochanteric fractures. While it contributes to overall stability, its specific function is rotational control, distinct from the primary lag screw which provides robust fixation in the femoral head and resists varus collapse. It does not primarily provide axial stability against shortening, interfragmentary compression, or act as a blocking screw for nail insertion.

Question 9262

Topic: 2. Trauma

A 40-year-old male with a transverse mid-shaft femoral fracture (AO/OTA 32-A3) is undergoing IM nailing. During nail insertion, a sudden increase in resistance is felt. What is the most likely immediate complication?

. Intraoperative infection.
. Iatrogenic fracture propagation.
. Femoral nerve injury.
. Fat embolism.
. Vascular injury due to excessive reaming.

Correct Answer & Explanation

. Iatrogenic fracture propagation.

Explanation

A sudden increase in resistance during nail insertion, especially in a transverse or short oblique fracture, often indicates impingement of the nail on the cortical bone, leading to iatrogenic fracture propagation or a burst fracture. This can be due to improper reduction, malalignment of the entry point, or using too large a nail for the canal. Intraoperative infection is a long-term risk, not an immediate event signaled by resistance. Femoral nerve injury is rare with IM nailing. Fat embolism can occur but doesn't manifest as resistance. Vascular injury is possible but usually with over-reaming or incorrect guidewire placement, not typically the 'sudden increase in resistance' of nail insertion.

Question 9263

Topic: 2. Trauma

Which of the following describes the 'flow-through' reaming technique in intramedullary nailing?

. Reaming only to the size of the smallest canal diameter.
. Reaming sequentially in decreasing increments to avoid heat buildup.
. Reaming at high speeds to quickly clear the canal.
. Reaming while simultaneously irrigating and aspirating to remove debris and reduce pressure.
. Reaming only through the proximal and distal fragments, skipping the fracture gap.

Correct Answer & Explanation

. Reaming while simultaneously irrigating and aspirating to remove debris and reduce pressure.

Explanation

The 'flow-through' reaming technique involves continuous irrigation and aspiration during reaming to actively remove bone debris, fat, and marrow from the medullary canal. This technique aims to reduce intramedullary pressure, decrease the risk of fat embolism, and minimize heat generation during reaming, potentially reducing endosteal damage. Reaming to the smallest diameter is often insufficient. Sequential reaming is standard but 'flow-through' refers to the irrigation/aspiration. High-speed reaming can increase heat. Skipping the fracture gap is not standard reaming.

Question 9264

Topic: 2. Trauma

A 55-year-old male presents with a comminuted humeral shaft fracture (AO/OTA 12-B2). What is a common pitfall when performing antegrade humeral IM nailing?

. Iatrogenic ulnar nerve injury during distal locking.
. Insufficient reaming leading to nail binding proximally.
. Malalignment in the sagittal plane (apex anterior or posterior angulation).
. Injury to the musculocutaneous nerve during entry portal creation.
. Excessive nail length causing impingement in the elbow joint.

Correct Answer & Explanation

. Malalignment in the sagittal plane (apex anterior or posterior angulation).

Explanation

Malalignment in the sagittal plane (apex anterior or posterior angulation) is a common pitfall in humeral shaft IM nailing, particularly with antegrade approaches. The natural anterior bow of the humerus can be challenging to follow with a straight nail, especially if reduction is not perfect. This can lead to malunion or impingement. Ulnar nerve injury is typically associated with very distal fractures or specific olecranon fossa nail designs, not generic distal locking. Musculocutaneous nerve injury is rare with entry portal creation. Excessive nail length is a potential issue but malalignment is more frequently cited. Insufficient reaming can occur but is correctable.

Question 9265

Topic: 2. Trauma

When performing retrograde femoral intramedullary nailing, which specific structure is most vulnerable to iatrogenic injury during nail insertion through the knee joint?

. Popliteal artery.
. Anterior cruciate ligament (ACL).
. Peroneal nerve.
. Patellar tendon.
. Medial collateral ligament (MCL).

Correct Answer & Explanation

. Anterior cruciate ligament (ACL).

Explanation

When performing retrograde femoral intramedullary nailing, the Anterior Cruciate Ligament (ACL) is most vulnerable to iatrogenic injury. The entry portal is typically created through the intercondylar notch, and improper placement (too anterior or posterior) or excessive reaming can damage the ACL fibers. The patellar tendon can also be irritated or injured, but ACL injury is a specific concern related to the notch entry. Popliteal artery and peroneal nerve are more posterior/lateral and generally less at risk with the standard entry. MCL is usually not at direct risk.

Question 9266

Topic: 2. Trauma

Which of the following is an advantage of a 'fixed-angle' or 'polyaxial' distal locking system in an IM nail?

. Allows for greater dynamization at the fracture site.
. Requires fewer locking screws for equivalent stability.
. Provides enhanced stability in comminuted metaphyseal-epiphyseal fractures.
. Reduces the overall profile of the nail, minimizing soft tissue irritation.
. Facilitates easier removal of the implant.

Correct Answer & Explanation

. Provides enhanced stability in comminuted metaphyseal-epiphyseal fractures.

Explanation

Fixed-angle or polyaxial distal locking systems provide enhanced stability, particularly in comminuted metaphyseal-epiphyseal fractures where the distal fragment is short and/or has poor bone quality. These systems allow screws to be angled and locked into the nail from multiple planes, providing a more robust construct that resists pullout and angulation, which is crucial in such challenging fracture patterns. They do not primarily allow for greater dynamization, require fewer screws, reduce the overall nail profile (often the opposite), or necessarily facilitate easier removal.

Question 9267

Topic: 2. Trauma

In the management of a segmental femoral shaft fracture, what is the primary biomechanical advantage of intramedullary nailing over plate fixation?

. Provides absolute stability at both fracture sites.
. Acts as a load-sharing device, reducing stress on the implant.
. Allows for anatomical reduction of all fragments.
. Minimizes periosteal stripping, preserving blood supply to all segments.
. Eliminates the need for distal locking.

Correct Answer & Explanation

. Minimizes periosteal stripping, preserving blood supply to all segments.

Explanation

For segmental femoral shaft fractures, intramedullary nailing is advantageous because it is a minimally invasive technique that involves less periosteal stripping compared to extensive open reduction and plating. This preservation of the soft tissue envelope and periosteal blood supply is critical for the healing of both fracture segments. IM nailing provides relative stability and is a load-sharing device, but the primary advantage over plate fixation in this context (especially for preserving biology) is the minimal soft tissue disruption. It does not provide absolute stability, nor does it typically allow for anatomical reduction of all fragments in a comminuted segmental fracture (often a bridging technique). Distal locking is still essential.

Question 9268

Topic: 2. Trauma

What is the typical time frame when intramedullary nail dynamization is considered for a delayed union in a femoral shaft fracture?

. Immediately post-op if healing is not progressing.
. At 2-4 weeks post-op if early callus is absent.
. At 3-6 months post-op if there are signs of delayed union but no progression to nonunion.
. Only after 12 months if nonunion is confirmed.
. Never, as dynamization increases instability.

Correct Answer & Explanation

. At 3-6 months post-op if there are signs of delayed union but no progression to nonunion.

Explanation

Intramedullary nail dynamization is typically considered for a delayed union in a femoral shaft fracture at approximately 3-6 months post-operatively, after an initial period of static locking. This is done when radiographs show signs of delayed union (persistent fracture line, minimal callus) but not yet definitive nonunion (which typically takes 6-9 months without progress). The goal is to allow controlled axial micromotion and increased load at the fracture site, stimulating callus formation. Dynamization immediately post-op or very early would destabilize the fracture. It is a specific intervention for delayed union, not for confirmed nonunion (which might require exchange nailing or bone grafting).

Question 9269

Topic: 2. Trauma

Which of the following describes the 'biological' principle of intramedullary nailing in fracture management?

. Rigid fixation promoting direct bone healing without callus.
. Extensive soft tissue dissection to expose the fracture site.
. Preservation of the periosteal blood supply and fracture hematoma.
. Achieving absolute interfragmentary compression.
. Relying solely on the reaming process to stimulate osteogenesis.

Correct Answer & Explanation

. Preservation of the periosteal blood supply and fracture hematoma.

Explanation

The 'biological' principle of intramedullary nailing refers to its minimally invasive nature, which preserves the crucial periosteal blood supply and the fracture hematoma. The fracture hematoma contains growth factors and progenitor cells essential for healing. By providing relative stability from within, IM nailing minimizes soft tissue disruption, thus enhancing the biological environment for secondary bone healing. Rigid fixation and absolute interfragmentary compression are principles of absolute stability, often associated with plating. Extensive soft tissue dissection is antithetical to biological fixation. While reaming does stimulate osteogenesis, it's not the sole biological principle, which encompasses the overall minimally invasive approach.

Question 9270

Topic: 2. Trauma

What is the appropriate management for a patient who develops a peroneal nerve palsy immediately after closed tibial intramedullary nailing, and the foot drop is complete?

. Observe for 6 weeks, then consider EMG studies.
. Immediate surgical exploration of the peroneal nerve.
. Physical therapy and AFO, assuming neuropraxia.
. Remove the intramedullary nail and external fixation.
. Administer high-dose steroids to reduce swelling.

Correct Answer & Explanation

. Immediate surgical exploration of the peroneal nerve.

Explanation

An immediate, complete peroneal nerve palsy after closed tibial intramedullary nailing warrants immediate surgical exploration. While a partial or transient palsy might be observed initially, a complete deficit suggests direct nerve injury, impingement by a screw, or nerve entrapment, which requires prompt identification and release to optimize the chances of recovery. Waiting for 6 weeks or simply observing with physical therapy would be inappropriate for a complete, acute deficit. Removing the nail or using external fixation is an overtreatment unless the nerve injury is confirmed to be directly caused by the implant itself and cannot be otherwise resolved. Steroids are not indicated for direct nerve trauma.

Question 9271

Topic: 2. Trauma

Which type of intramedullary nail is specifically designed to address the wide metaphyseal canal and osteoporotic bone typically found in pertrochanteric hip fractures?

. Standard straight diaphyseal nail.
. Flexible Ender nails.
. Solid unreamed nail.
. Cephalomedullary nail with a larger proximal diameter and locking in the femoral head.
. Antegrade humerus nail.

Correct Answer & Explanation

. Cephalomedullary nail with a larger proximal diameter and locking in the femoral head.

Explanation

Cephalomedullary nails are specifically designed for proximal femoral fractures (including pertrochanteric and subtrochanteric fractures). They feature a wider proximal segment that fits the metaphyseal canal and includes a lag screw (or screws/blade) that extends into the femoral head, providing robust fixation in often osteoporotic bone. Standard diaphyseal nails are too narrow proximally and lack head fixation. Flexible Ender nails are historical and largely abandoned. Solid unreamed nails are primarily for diaphyseal fractures. Antegrade humerus nails are for the humerus.

Question 9272

Topic: 2. Trauma

A 48-year-old male presents with a nonunion of a previously plated humeral shaft fracture. He undergoes exchange nailing. What is the primary advantage of exchange nailing over repeat plating in this scenario?

. Provides absolute stability at the nonunion site.
. Converts an external healing environment to an internal one.
. Minimizes iatrogenic bone loss and periosteal stripping.
. Removes compromised bone and introduces osteogenic factors from reaming.
. Allows for easier postoperative rehabilitation.

Correct Answer & Explanation

. Removes compromised bone and introduces osteogenic factors from reaming.

Explanation

Exchange nailing for a hypertrophic or oligotrophic nonunion has several advantages, but a key one is that it removes the fibrous tissue at the nonunion site and introduces osteogenic factors. The reaming process stimulates the endosteal blood supply, brings in new mesenchymal stem cells, and provides a larger, stiffer nail (often over-reamed by 2mm compared to previous nail) that can penetrate the sclerotic bone ends and provide improved mechanical stability. It also optimizes the intramedullary environment for healing. While it minimizes further periosteal stripping compared to repeat plating, the 'reaming effect' is a primary biological advantage. It provides relative stability, not absolute. It doesn't convert an 'external' healing environment to an 'internal' one in the sense of soft tissue, as the previous plate was already an internal fixation. Ease of rehab is secondary.

Question 9273

Topic: 2. Trauma

What is the main concern when using a very long intramedullary nail in a short statured individual with a femoral shaft fracture?

. Increased risk of deep vein thrombosis.
. Difficulty with distal locking due to anatomical variations.
. Impingement of the nail on the distal femoral epiphysis or knee joint.
. Higher rate of nonunion due to stress shielding.
. Challenges with proximal entry point due to hip anatomy.

Correct Answer & Explanation

. Impingement of the nail on the distal femoral epiphysis or knee joint.

Explanation

When using a very long intramedullary nail, particularly in a short-statured individual, there is a significant risk of impingement of the nail on the distal femoral epiphysis or even penetration into the knee joint. This can lead to pain, restricted motion, and articular damage. Careful preoperative templating and intraoperative imaging are crucial to select the correct nail length and prevent this complication. While distal locking can have challenges, nail length is a specific issue for impingement. Stress shielding and DVT are not primarily linked to nail length in this context. Proximal entry point challenges are related to hip anatomy/surgical approach, not specifically nail length for short stature.

Question 9274

Topic: 2. Trauma

When should prophylactic antibiotics be administered for intramedullary nailing, according to current guidelines?

. Immediately postoperatively, for 24 hours.
. Within 60 minutes prior to surgical incision.
. At the time of fracture reduction on the traction table.
. After reaming is complete, prior to nail insertion.
. Only for open fractures or immunocompromised patients.

Correct Answer & Explanation

. Within 60 minutes prior to surgical incision.

Explanation

Current guidelines recommend administering prophylactic antibiotics within 60 minutes (or 120 minutes for vancomycin/fluoroquinolones) prior to surgical incision. This ensures adequate tissue levels of the antibiotic at the time of potential bacterial exposure during surgery, significantly reducing the risk of surgical site infection. Administering them postoperatively or later during the procedure reduces their effectiveness for prophylaxis. Prophylactic antibiotics are standard for all orthopedic implant surgeries, not just open fractures or immunocompromised patients, though those groups may receive broader spectrum or longer courses.

Question 9275

Topic: 2. Trauma

Which complication is specifically associated with the use of a piriformis fossa entry portal for femoral IM nailing in younger patients?

. Trochanteric bursitis.
. Avascular necrosis of the femoral head.
. Damage to the sciatic nerve.
. Shortening of the limb.
. Infection of the knee joint.

Correct Answer & Explanation

. Avascular necrosis of the femoral head.

Explanation

In younger patients, especially those with an intact blood supply to the femoral head, a piriformis fossa entry portal for femoral IM nailing carries a higher theoretical and sometimes actual risk of avascular necrosis (AVN) of the femoral head. This is because the entry point, if placed too medial or with excessive reaming, can disrupt the critical retinacular blood supply to the femoral head. While this is a concern in all ages, younger patients have a higher demand for blood supply due to greater activity and healing potential, making the consequence of disruption potentially more severe. Lateral trochanteric entry points are often preferred in younger patients to mitigate this risk. Trochanteric bursitis is more common with prominent hardware at the greater trochanter. Sciatic nerve damage is rare. Shortening is a fracture reduction issue. Infection of the knee joint is unrelated.

Question 9276

Topic: 2. Trauma

What is the purpose of using a 'back-slap' technique during distal locking of an IM nail?

. To provide axial compression across the fracture site.
. To ensure proper nail seating within the medullary canal.
. To distract the fracture fragments for better alignment.
. To advance the distal locking guide into the proper position.
. To test the rotational stability of the construct.

Correct Answer & Explanation

. To provide axial compression across the fracture site.

Explanation

The 'back-slap' technique, typically performed by gently impacting the proximal end of the nail with a mallet after inserting proximal locking screws but before distal locking, is used to provide axial compression across the fracture site. This maneuver can close any remaining fracture gap, promoting better bone-to-bone contact and potentially accelerating healing, especially in oblique or spiral fractures. It is not for nail seating, distraction, advancing the guide, or testing rotational stability directly.

Question 9277

Topic: 2. Trauma

In the context of dynamic locking in IM nailing, what is the primary benefit?

. Prevents all micromotion at the fracture site.
. Allows for controlled axial collapse and compression.
. Increases torsional stability compared to static locking.
. Facilitates rapid removal of the nail post-union.
. Reduces the risk of fat embolism.

Correct Answer & Explanation

. Allows for controlled axial collapse and compression.

Explanation

Dynamic locking allows for controlled axial collapse and compression at the fracture site while still controlling rotation. This controlled micromotion and compression can stimulate callus formation and accelerate healing, particularly in transverse or short oblique fractures where some axial load is beneficial. It does not prevent all micromotion; that's the goal of absolute stability. It provides less torsional stability than static locking. Facilitating nail removal or reducing fat embolism risk are not primary benefits.

Question 9278

Topic: 2. Trauma

For a patient with a proximal third tibial shaft fracture, what is a specific challenge of intramedullary nailing compared to a mid-shaft fracture?

. Increased risk of vascular injury due to the popliteal vessels.
. Difficulty in achieving appropriate nail length.
. Higher incidence of nonunion due to poor bone quality.
. Challenges in controlling sagittal plane alignment (e.g., procurvatum).
. Increased risk of peroneal nerve injury during distal locking.

Correct Answer & Explanation

. Challenges in controlling sagittal plane alignment (e.g., procurvatum).

Explanation

Proximal third tibial shaft fractures present significant challenges in controlling sagittal plane alignment, often leading to apex anterior (procurvatum) malunion. This is due to the widening of the medullary canal proximally, the pull of the gastrocnemius on the distal fragment, and the difficulty in inserting a straight nail into the naturally anteriorly bowed tibia. Specific reduction techniques (e.g., using blocking screws, a unicortical plate as a joystick) are often required. Vascular injury and peroneal nerve injury are possible but not specific to the proximal third, and generally higher with distal/metaphyseal fractures. Nail length is not inherently more challenging. Nonunion rates can be higher, but sagittal plane malalignment is a hallmark problem.

Question 9279

Topic: 2. Trauma

What is the primary concern regarding the use of reamed IM nailing in a patient with a known history of severe cardiac valvular disease?

. Increased risk of deep vein thrombosis.
. Potential for cardiac arrhythmia due to pain.
. Exacerbation of cardiac compromise due to fat embolism and inflammatory response.
. Difficulty with positioning due to limited mobility.
. Drug interactions with cardiac medications.

Correct Answer & Explanation

. Exacerbation of cardiac compromise due to fat embolism and inflammatory response.

Explanation

The primary concern with reamed IM nailing in a patient with severe cardiac valvular disease is the potential exacerbation of cardiac compromise due to fat embolism and the systemic inflammatory response. Reaming can release fat emboli and inflammatory mediators into the circulation, which can put additional stress on an already compromised cardiovascular system, potentially leading to cardiac decompensation, arrhythmias, or myocardial infarction. While DVT is a general risk, and positioning or drug interactions are considerations, the specific physiological stress of FES and inflammation is the most direct and severe concern for a patient with severe valvular disease. Cardiac arrhythmia due to pain is less direct or severe.

Question 9280

Topic: 2. Trauma

A 25-year-old male sustains a spiral subtrochanteric femur fracture (AO/OTA 32-B3). He is treated with a long cephalomedullary nail. What is a key biomechanical advantage of this implant over a dynamic hip screw (DHS) for this specific fracture pattern?

. The IM nail allows for a larger lag screw diameter.
. The IM nail provides greater resistance to medialization of the distal fragment.
. The DHS promotes better compression at the fracture site.
. The DHS has a lower risk of causing iatrogenic femoral shaft fracture.
. The IM nail avoids interference with distal femoral blood supply.

Correct Answer & Explanation

. The IM nail provides greater resistance to medialization of the distal fragment.

Explanation

For spiral subtrochanteric fractures, especially those that are comminuted or reverse obliquity (though this is B3), the primary biomechanical advantage of a long cephalomedullary nail over a DHS is its superior resistance to medialization of the distal fragment. Being load-sharing and intramedullary, the nail better resists the powerful adduction forces that tend to displace the distal fragment medially, leading to varus collapse. A DHS is a load-bearing device that is eccentric and less effective in resisting these forces, often leading to failure in unstable subtrochanteric fractures. Lag screw diameter is not a primary differentiator. DHS promotes compression, but at the cost of stability in unstable fractures. DHS has a higher risk of stress riser/fracture distal to the plate. Blood supply is not a primary differentiating factor for this comparison.

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