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2. Trauma MCQs

Practice Set 474 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 9461

Topic: 2. Trauma

What is the biomechanical risk associated with reaming through a previously unreamed intramedullary nail in situ (e.g., for revision surgery)?

. Increased risk of implant infection.
. Damage to the reamer, making it unusable.
. Iatrogenic thermal necrosis due to concentrated heat and friction.
. Reduced bending stiffness of the nail after reaming.
. Inability to remove the old nail.

Correct Answer & Explanation

. Iatrogenic thermal necrosis due to concentrated heat and friction.

Explanation

Attempting to ream over a previously unreamed intramedullary nail (especially if it's not designed for reaming, e.g., some older unreamed nails) creates immense friction and concentrated heat between the reamer, the nail, and the bone. This can easily lead to severe thermal osteonecrosis of the bone, as well as potential binding or breakage of the reamer. If the reaming is intended to remove fibrous tissue in a nonunion, it's typically done after nail removal, or with specialized instruments. It's a high-risk procedure for bone viability.

Question 9462

Topic: 2. Trauma

In a comminuted ipsilateral femoral neck and shaft fracture, what is the biomechanical rationale for using a reconstruction (recon) nail over a standard femoral shaft nail?

. Recon nails are inherently stronger in bending.
. Recon nails promote faster healing of the shaft fracture.
. Recon nails allow for independent, multi-planar fixation of the femoral neck fracture while stabilizing the shaft.
. Recon nails are designed for unreamed insertion only.
. Recon nails have a lower risk of infection.

Correct Answer & Explanation

. Recon nails allow for independent, multi-planar fixation of the femoral neck fracture while stabilizing the shaft.

Explanation

Ipsilateral femoral neck and shaft fractures are complex, requiring stable fixation of both components. Standard femoral shaft nails are designed primarily for diaphyseal stabilization and offer limited or inadequate fixation for the femoral neck component. Reconstruction (recon) nails are specifically designed with proximal locking options (e.g., two or three screws that diverge into the femoral head and neck) that provide independent, multi-planar stabilization of the femoral neck fracture while simultaneously providing stable fixation of the femoral shaft fracture. This dual-stability is the key biomechanical advantage. They are not inherently stronger, faster healing, or unreamed only, and infection risk is similar.

Question 9463

Topic: 2. Trauma

What is the biomechanical consequence of a 'too-short' intramedullary nail in a diaphyseal fracture?

. Increased torsional stiffness of the construct.
. Reduced risk of periprosthetic fracture at the nail ends.
. Stress concentration at the nail tips, increasing the risk of periprosthetic fracture.
. Promotion of primary bone healing due to localized compression.
. Easier removal of the nail in the future.

Correct Answer & Explanation

. Stress concentration at the nail tips, increasing the risk of periprosthetic fracture.

Explanation

A too-short intramedullary nail means its ends terminate within the diaphysis, often in relatively narrow or highly stressed cortical bone. This creates stress risers at the nail tips. Biomechanically, loads are abruptly transferred from the stiff nail to the bone at these points, leading to stress concentration which significantly increases the risk of a periprosthetic fracture occurring just beyond the nail tip. Optimal nail length involves extending into the metaphysis to distribute stress over a larger area and avoid these stress risers.

Question 9464

Topic: 2. Trauma

For a comminuted distal tibia fracture, why might an IM nail be biomechanically advantageous over a locking plate when considering the soft tissue envelope?

. IM nails provide more rigid fixation.
. IM nails offer absolute stability for the articular surface.
. IM nails allow for less soft tissue stripping and preservation of periosteal blood supply.
. IM nails are stronger in resisting axial compression.
. IM nails eliminate the need for interlocking screws.

Correct Answer & Explanation

. IM nails allow for less soft tissue stripping and preservation of periosteal blood supply.

Explanation

Distal tibia fractures, especially comminuted ones, often have compromised soft tissue envelopes (thin skin, limited muscle coverage). Open reduction and internal fixation with plates can necessitate extensive soft tissue stripping, further jeopardizing vascularity and increasing the risk of wound complications and delayed healing. Intramedullary nailing, by utilizing a minimally invasive approach and being placed centrally, preserves the periosteal blood supply and minimizes soft tissue disruption, which is a significant biomechanical and biological advantage for healing. IM nails typically provide relative, not absolute, stability, and require interlocking screws.

Question 9465

Topic: Lower Extremity Trauma

The 'isthmus' of a long bone's medullary canal is biomechanically significant because:

. It is the weakest point of the bone.
. It represents the widest part of the canal, allowing easy nail insertion.
. It is the narrowest part, providing excellent cortical contact and inherent stability for IM nails.
. It is the primary site for bone marrow harvest.
. It is where interlocking screws are exclusively placed.

Correct Answer & Explanation

. It is the narrowest part, providing excellent cortical contact and inherent stability for IM nails.

Explanation

The isthmus is the narrowest part of the medullary canal in the diaphysis of a long bone. Biomechanically, this anatomical feature is highly advantageous for intramedullary nailing. When a nail is properly sized and inserted, it creates a tight 'three-point fixation' within the isthmus, providing significant inherent bending and torsional stability even before interlocking screws are placed. This tight cortical contact maximizes the load-sharing capacity of the nail with the bone. It is not necessarily the weakest part, and interlocking screws are placed proximally and distally, not just at the isthmus.

Question 9466

Topic: 2. Trauma

What is the biomechanical reason for placing the entry reamer centrally and slightly anterior in the tibial plateau for antegrade tibial nailing?

. To avoid the popliteal artery.
. To prevent iatrogenic malunion in procurvatum or recurvatum.
. To ensure maximal bone density at the entry point.
. To allow for easier reamer passage into the metaphysis.
. To achieve rotational stability of the entry reamer.

Correct Answer & Explanation

. To prevent iatrogenic malunion in procurvatum or recurvatum.

Explanation

The sagittal plane entry point for antegrade tibial nailing is crucial. Placing the entry reamer (and subsequently the nail) too anterior or too posterior can lead to procurvatum or recurvatum malalignment, respectively, in the healed fracture. A central, slightly anterior entry point aims to align the nail with the natural anterior bow of the tibia, allowing the nail to follow the canal's axis and prevent iatrogenic sagittal plane deformity. Avoiding the popliteal artery is critical but primarily influenced by maintaining the correct AP trajectory, not sagittal. Maximal bone density and reamer passage are less specific biomechanical reasons for this precise entry point.

Question 9467

Topic: 2. Trauma

Which of the following describes the biomechanical purpose of 'back-reaming' during IM nailing?

. To remove bone debris from the medullary canal.
. To prepare the distal fragment for interlocking screw insertion.
. To re-establish a communication between the two main fracture fragments.
. To remove sclerotic bone in a nonunion to allow for better vascularity and nail-bone contact.
. To create space for bone graft at the fracture site.

Correct Answer & Explanation

. To remove sclerotic bone in a nonunion to allow for better vascularity and nail-bone contact.

Explanation

Back-reaming is a technique used, particularly in the management of nonunions. Biomechanically, its purpose is to remove sclerotic, avascular bone and any interposed fibrous tissue at the nonunion site. This creates fresh, bleeding bone surfaces which are biologically more receptive to healing. It also prepares the canal for a potentially larger diameter nail and/or allows for impaction of the fragments, improving mechanical stability and promoting a more favorable biological environment for union. While it removes debris, the primary purpose is to address the nonunion pathology. It's not for routine interlocking or re-establishing communication between healthy fragments.

Question 9468

Topic: Lower Extremity Trauma

Biomechanically, why is it generally recommended to fully seat an IM nail to avoid distal protrusion?

. To improve the cosmetic appearance of the limb.
. To prevent neurovascular injury near the distal joint.
. To increase the effective working length of the nail.
. To avoid pain, irritation, and potential joint impingement or articular damage.
. To facilitate easier removal of the nail in the future.

Correct Answer & Explanation

. To avoid pain, irritation, and potential joint impingement or articular damage.

Explanation

A distally protruding intramedullary nail can cause significant problems. Biomechanically, the nail tip can impinge on the articular cartilage or subchondral bone, leading to pain, joint irritation, reduced range of motion, and potentially long-term articular damage and post-traumatic arthritis. In some locations (e.g., knee, ankle), it can also cause soft tissue irritation. Therefore, proper seating of the nail is crucial to avoid these complications. Neurovascular injury is possible but the primary biomechanical and clinical concern of distal protrusion is joint and soft tissue irritation. It does not increase working length or necessarily facilitate removal.

Question 9469

Topic: 2. Trauma

A 28-year-old male sustains a closed comminuted mid-diaphyseal femoral shaft fracture. During reamed intramedullary nailing, which intraoperative event poses the greatest risk for systemic fat embolism syndrome?

. A. Initial guide wire insertion across the fracture.
. B. Sequential reaming of the medullary canal.
. C. Distal locking screw insertion.
. D. Proximal nail insertion.
. E. Manual reduction maneuvers.

Correct Answer & Explanation

. B. Sequential reaming of the medullary canal.

Explanation

Sequential reaming of the medullary canal generates the highest sustained intramedullary pressure, forcing marrow contents, including fat globules, into the venous circulation. This pressure surge is the most significant identifiable intraoperative event contributing to the risk of systemic fat embolism syndrome (FES). While guide wire insertion, nail insertion, and reduction maneuvers also cause transient pressure increases, reaming is the most prominent factor.

Question 9470

Topic: 2. Trauma

A 60-year-old female with osteoporosis sustains a transverse mid-diaphyseal humeral fracture. Which of the following is the most appropriate indication for intramedullary nailing in this patient?

. A. To achieve absolute stability and primary bone healing.
. B. As the primary treatment for all humeral shaft fractures in osteoporotic patients.
. C. To allow early functional range of motion and reduce nonunion risk in an unstable fracture.
. D. Due to its superior rotational stability compared to plating in all cases.
. E. To completely eliminate the need for bracing post-operatively.

Correct Answer & Explanation

. C. To allow early functional range of motion and reduce nonunion risk in an unstable fracture.

Explanation

In unstable humeral shaft fractures, especially in osteoporotic patients, intramedullary nailing can provide good stability, allowing for earlier functional rehabilitation and potentially reducing the risk of nonunion compared to non-operative treatment, or providing an alternative to plating. Intramedullary nails primarily achieve relative stability and promote secondary bone healing (A). It is not the primary treatment forallhumeral shaft fractures (B), as many are managed non-operatively. Rotational stability of a nail can be excellent with appropriate locking, but plating can also provide very good rotational control (D), and sometimes better. While a nail provides internal support, bracing or sling immobilization is often still recommended post-operatively (E) to protect the healing bone and prevent excessive stress.

Question 9471

Topic: 2. Trauma

A 70-year-old male with a long-standing history of diabetes and peripheral vascular disease sustains a closed distal tibial shaft fracture (AO/OTA 43-A1). Which factor most strongly argues against the use of a reamed intramedullary nail in this patient?

. A. Fracture pattern being simple transverse.
. B. Presence of significant peripheral neuropathy.
. C. Increased risk of nonunion due to diabetes.
. D. Compromised soft tissues and vascularity at the fracture site.
. E. Risk of post-operative anterior knee pain.

Correct Answer & Explanation

. D. Compromised soft tissues and vascularity at the fracture site.

Explanation

In a patient with diabetes and peripheral vascular disease, compromised soft tissues and vascularity (D) are critical concerns that argue against reamed intramedullary nailing, especially in the distal tibia. Reaming further disrupts the endosteal blood supply, and if the periosteal supply is already diminished due to disease, it can significantly increase the risk of delayed union, nonunion, or wound complications. While neuropathy (B) and diabetes (C) generally increase nonunion risk, the direct impact of reaming on a pre-compromised vascular bed is a specific concern. Simple transverse patterns (A) are generally amenable to nailing. Anterior knee pain (E) is a common complication but not a contraindication.

Question 9472

Topic: 2. Trauma

Which of the following statements regarding the dynamic locking option in intramedullary nailing is most accurate?

. A. Dynamic locking provides absolute stability and prevents micromotion at the fracture site.
. B. Dynamic locking is primarily used in comminuted fractures to prevent shortening.
. C. Dynamic locking allows controlled axial micromotion, which can stimulate callus formation.
. D. Dynamic locking refers to a nail without any locking screws.
. E. Dynamic locking is contraindicated in all tibial shaft fractures.

Correct Answer & Explanation

. C. Dynamic locking allows controlled axial micromotion, which can stimulate callus formation.

Explanation

Dynamic locking (often achieved by only placing locking screws on one side of a slotted hole or by removing a screw after initial rigid fixation) allows for controlled axial micromotion at the fracture site. This micromotion, when within a physiological range, can act as a biomechanical stimulus for callus formation and secondary bone healing. It does not provide absolute stability (A). It is generally avoided in highly comminuted or unstable fractures (B) where prevention of shortening is paramount, favoring static locking initially. Dynamic locking involves specific screw placement (D), not the absence of screws. It is not contraindicated inalltibial shaft fractures (E); it can be useful in simple, well-reduced fractures where some controlled load-sharing is desired.

Question 9473

Topic: 2. Trauma

A 30-year-old male sustains a closed comminuted mid-shaft humerus fracture (AO/OTA 12-B2). Considering the functional outcomes and complication rates, which is the most common reason for choosing a locked intramedullary nail over plate fixation in this specific case?

. A. Reduced risk of iatrogenic radial nerve palsy.
. B. Superior biomechanical stability in all planes of motion.
. C. Ability to provide a load-sharing construct, allowing for earlier functional rehabilitation.
. D. Lower incidence of shoulder impingement symptoms.
. E. Elimination of the need for an incision.

Correct Answer & Explanation

. C. Ability to provide a load-sharing construct, allowing for earlier functional rehabilitation.

Explanation

For comminuted humeral shaft fractures, intramedullary nailing provides a load-sharing construct that can allow for earlier functional rehabilitation and reduced nonunion rates compared to non-operative management. It is particularly advantageous in comminuted patterns where plate fixation might require extensive periosteal stripping. The risk of radial nerve palsy (A) is typically lower with nailing compared to plating, but thereason for choosingin this scenario leans towards load-sharing. Plating can provide excellent stability (B). Shoulder impingement (D) is a known complication of antegrade humeral nailing due to hardware prominence, making this statement incorrect. Nailing still requires an incision (E).

Question 9474

Topic: 2. Trauma

When performing antegrade femoral intramedullary nailing, a common technical pitfall is an improper entry point. What is the consequence of an entry point that is too lateral in the piriformis fossa?

. A. Increased risk of nonunion due to disrupted blood supply to the femoral head.
. B. Iatrogenic avascular necrosis of the femoral head.
. C. Varus malalignment of the fracture and difficulty guiding the nail distally.
. D. Increased risk of a distal condylar fracture.
. E. Damage to the gluteus medius insertion, leading to abductor weakness.

Correct Answer & Explanation

. C. Varus malalignment of the fracture and difficulty guiding the nail distally.

Explanation

An entry point that is too lateral in the piriformis fossa, or on the greater trochanter, particularly if using a straight nail, can lead to varus malalignment of the fracture due to impingement on the lateral femoral cortex. It can also make it difficult to guide the nail centrally down the medullary canal. While AVN (B) is a risk if the entry point is too medial or damages the medial femoral circumflex artery, a too lateral entry is more commonly associated with malalignment. Damage to gluteus medius (E) is a risk with any trochanteric entry, but the biomechanical consequence of a too lateral entry on alignment is more specific. Nonunion (A) or distal fractures (D) are less direct consequences of this specific entry point error.

Question 9475

Topic: 2. Trauma

A 55-year-old obese patient sustains an isolated closed transverse mid-shaft tibia fracture. He is medically fit for surgery. What is the most significant biomechanical advantage of intramedullary nailing over plate osteosynthesis for this specific fracture in this patient?

. A. Intramedullary nails are less likely to experience fatigue failure.
. B. Nailing preserves the periosteal blood supply to a greater extent.
. C. IM nails provide a load-sharing construct, reducing stress shielding.
. D. Plates are more prone to infection in obese patients.
. E. Nails require smaller incisions, reducing soft tissue trauma.

Correct Answer & Explanation

. C. IM nails provide a load-sharing construct, reducing stress shielding.

Explanation

Intramedullary nails provide a load-sharing construct, meaning they share the load with the bone, rather than completely shielding the bone from stress (stress shielding), as can occur with rigid plates. This load sharing promotes secondary bone healing and reduces the risk of plate-related complications like refracture after hardware removal. While nails generally involve smaller incisions (E) and can preserve periosteal blood supply better than extensive plating (B), the fundamental biomechanical advantage is load sharing, which is particularly beneficial in a challenging healing environment like an obese patient. Fatigue failure (A) depends on nail design and fracture stability. Infection risk (D) is complex and not solely determined by implant type.

Question 9476

Topic: 2. Trauma
In the context of intramedullary nailing of an open tibial shaft fracture (Gustilo-Anderson Type IIIA), what is the most critical immediate step to reduce the risk of deep infection?
. Administration of systemic broad-spectrum antibiotics within 6 hours of injury.
. Aggressive debridement of all devitalized tissue and thorough irrigation.
. Primary closure of the wound over the nail.
. Application of negative pressure wound therapy.
. Early weight-bearing to promote bone healing.

Correct Answer & Explanation

. Aggressive debridement of all devitalized tissue and thorough irrigation.

Explanation

For open fractures, aggressive surgical debridement of all devitalized tissue and copious irrigation are paramount to reduce the bacterial load and prevent deep infection. While systemic antibiotics (A) are crucial and should be initiated early, and negative pressure wound therapy (D) can be beneficial, the surgical cleaning of the wound (B) is the most critical intraoperative step. Primary closure (C) of Type IIIA wounds is often avoided, favoring delayed closure or skin grafting. Early weight-bearing (E) is important for healing but does not directly reduce infection risk.

Question 9477

Topic: 2. Trauma

Which of the following describes the 'nail-within-a-nail' technique and its primary application?

. A. Inserting a smaller diameter nail into a larger one for increased rotational stability in comminuted fractures.
. B. Placing a second, smaller IM nail inside the first for greater rigidity in nonunions with bone loss.
. C. Using a reamed nail followed by an unreamed nail in segmental fractures.
. D. A technique for removing broken intramedullary nails.
. E. A method for augmenting intramedullary fixation in pediatric fractures.

Correct Answer & Explanation

. B. Placing a second, smaller IM nail inside the first for greater rigidity in nonunions with bone loss.

Explanation

The 'nail-within-a-nail' technique involves inserting a smaller diameter intramedullary nail into an existing, larger diameter nail. This is primarily used to increase the rotational and bending stiffness of the construct, particularly in cases of established nonunion, impending hardware failure, or in very comminuted fractures where additional stability is required. It's a method to augment fixation and achieve a stiffer construct.

Question 9478

Topic: 2. Trauma

What is the primary rationale for advocating for a limited reaming strategy in certain clinical scenarios for intramedullary nailing?

. A. To achieve a tighter fit of the nail and increase stability.
. B. To reduce the risk of fat embolism syndrome and preserve endosteal blood supply.
. C. To prevent heat necrosis of the bone during reaming.
. D. To allow for earlier weight-bearing than standard reaming.
. E. To decrease operative time in polytrauma patients.

Correct Answer & Explanation

. B. To reduce the risk of fat embolism syndrome and preserve endosteal blood supply.

Explanation

Limited reaming, or avoiding reaming altogether (unreamed nailing), is primarily advocated to reduce the risk of fat embolism syndrome by minimizing intramedullary pressure increases and to preserve the endosteal blood supply, especially in compromised host situations (e.g., polytrauma, open fractures). While heat necrosis (C) can occur, and operative time (E) might be slightly reduced, the main biological benefits are related to FES prevention and blood supply preservation. A tighter fit (A) and earlier weight-bearing (D) are generally benefits ofreamednailing and larger nails, not limited reaming.

Question 9479

Topic: 2. Trauma

A 32-year-old male sustains a closed segmental femoral shaft fracture (AO/OTA 32-C2). Which of the following potential complications is most likely with intramedullary nailing of this specific fracture pattern?

. A. Infection.
. B. Fat embolism syndrome.
. C. Nonunion of one or both segments.
. D. Anterior knee pain.
. E. Malrotation.

Correct Answer & Explanation

. C. Nonunion of one or both segments.

Explanation

Segmental femoral shaft fractures (C2) present a significant challenge for bone healing due to the severe disruption of blood supply to the intermediate segment. As such, nonunion (C) of one or both fracture segments is a relatively high risk, even with stable intramedullary fixation. While infection (A), FES (B), anterior knee pain (D), and malrotation (E) are all potential complications of femoral nailing, the specific comminution and devascularization inherent in a segmental fracture elevate the risk of nonunion. FES risk is related to reaming, not specifically the fracture pattern's geometry.

Question 9480

Topic: 2. Trauma

A 75-year-old female with a long spiral distal femoral fracture extending into the supracondylar region (AO/OTA 33-A2) is planned for retrograde intramedullary nailing. Which specific technical consideration is most critical to avoid malreduction and achieve stable fixation in this type of fracture?

. A. Minimizing reaming to preserve blood supply.
. B. Using a nail with a larger diameter and more distal locking options.
. C. Ensuring meticulous reduction of the articular surface fragments first.
. D. Prophylactic fasciotomy due to risk of compartment syndrome.
. E. Avoiding external rotation of the distal fragment.

Correct Answer & Explanation

. B. Using a nail with a larger diameter and more distal locking options.

Explanation

For distal femoral fractures extending into the supracondylar region, the primary challenge with retrograde nailing is achieving stable fixation in the short distal segment, especially in osteoporotic bone. A nail with a larger diameter and, critically, multiple and diverse distal locking options (e.g., multiplanar screws, diverging screws) is essential to maximize purchase and prevent cutout in the short, often osteoporotic, distal fragment. Minimizing reaming (A) is for biological reasons, not stability. Articular reduction (C) is paramount for articular fractures (Type C), not typically for A2. Fasciotomy (D) is not routinely indicated. Avoiding external rotation (E) is a general reduction principle.

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