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2. Trauma MCQs

Practice Set 336 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 6701

Topic: 2. Trauma

A 15-year-old boy presents with progressive numbness and tingling in his ring and small fingers. He sustained an elbow fracture at age 4 that was treated nonoperatively. Examination reveals weakness of intrinsic hand muscles. What elbow deformity is most likely present and responsible for his current symptoms?

. Cubitus varus
. Cubitus valgus
. Madelung deformity
. Gunstock deformity
. Radiocapitellar subluxation

Correct Answer & Explanation

. Cubitus valgus

Explanation

The patient has a tardy ulnar nerve palsy, a classic complication of a nonunion of a pediatric lateral condyle fracture. This nonunion results in a progressive cubitus valgus deformity, stretching the ulnar nerve over time.

Question 6702

Topic: 2. Trauma

A 4-year-old boy sustains an isolated, closed diaphyseal fracture of the right femur with 1.5 cm of shortening. He has no other injuries. What is the most appropriate definitive management for this patient?

. Flexible intramedullary nailing
. Submuscular bridge plating
. Rigid locked intramedullary nailing
. Early spica cast application
. External fixation

Correct Answer & Explanation

. Early spica cast application

Explanation

For children aged 1 to 5 years with an isolated femur fracture and acceptable shortening (< 2-3 cm), early spica casting remains the gold standard of treatment. Flexible nails are generally preferred for children older than 5.

Question 6703

Topic: 2. Trauma
A 6-year-old girl falls onto an outstretched arm. Radiographs demonstrate an anterior bowing plastic deformation of the ulnar diaphysis combined with an anterior dislocation of the radial head. This injury pattern corresponds to which type of Bado classification?
. Bado Type I
. Bado Type II
. Bado Type III
. Bado Type IV
. Bado Type V

Correct Answer & Explanation

. Bado Type I

Explanation

A Bado Type I Monteggia lesion features an anterior dislocation of the radial head with an anteriorly angulated ulnar shaft fracture (or plastic deformation). It is the most common Monteggia variant in children.

Question 6704

Topic: 2. Trauma

A 75-year-old woman sustains a supracondylar femur fracture just above a well-fixed, closed-box posterior-stabilized (PS) TKA femoral component.

What is the preferred method of fixation for this Lewis-Rorabeck Type II fracture?

. Retrograde intramedullary nailing
. Revision of the femoral component to a distal femoral replacement
. Open reduction and internal fixation with a lateral locked plate
. Antegrade intramedullary nailing
. Nonoperative management with skeletal traction

Correct Answer & Explanation

. Open reduction and internal fixation with a lateral locked plate

Explanation

Because the PS TKA component has a closed-box design, a retrograde intramedullary nail cannot be passed through the intercondylar notch. The best option for a fracture above a well-fixed, closed-box component is ORIF with a lateral locked plate.

Question 6705

Topic: Lower Extremity Trauma

A patient presents for total knee arthroplasty with an extra-articular diaphyseal femoral deformity consisting of 15 degrees of varus bowing. According to established alignment principles, what is the best intra-articular adjustment to achieve a neutral postoperative mechanical axis without performing a corrective femoral osteotomy?

. Increase the valgus cut angle of the distal femur
. Decrease the valgus cut angle of the distal femur
. Make a standard 5-degree valgus cut and use a thicker medial polyethylene
. Translate the femoral component laterally
. Under-resect the medial tibial plateau

Correct Answer & Explanation

. Increase the valgus cut angle of the distal femur

Explanation

For a varus extra-articular femoral bowing deformity, the mechanical axis drops medially. To compensate intra-articularly and restore a neutral mechanical axis perpendicular to the floor, the surgeon must increase the valgus angle of the distal femoral cut beyond the standard 5 to 7 degrees.

Question 6706

Topic: 2. Trauma

An 80-year-old female with a well-functioning TKA falls and sustains a supracondylar femur fracture. Radiographs show a displaced fracture, but the femoral component remains radiographically well-fixed (Rorabeck Type II). What is the most appropriate management?

. Conservative management in a hinged knee brace
. Retrograde intramedullary nailing or locked plating
. Revision to a distal femoral replacement
. Revision to a long-stem cemented femoral component
. Open reduction and cerclage wiring alone

Correct Answer & Explanation

. Retrograde intramedullary nailing or locked plating

Explanation

For Rorabeck Type II fractures (displaced fracture, stable component), surgical fixation using a retrograde intramedullary nail or a lateral locked plate provides stable fixation while preserving the functioning arthroplasty.

Question 6707

Topic: 2. Trauma



A 72-year-old man presents with thigh pain after a fall. Imaging shows a periprosthetic femur fracture around a cemented polished taper slip stem extending to the tip of the stem. The stem is loose, but there is adequate proximal bone stock. What is the most appropriate treatment?

. Open reduction internal fixation (ORIF) with cables alone
. ORIF with a lateral locking plate
. Revision to a long fully porous-coated cementless stem
. Revision to a standard length cemented stem with cerclage wires
. Proximal femoral replacement

Correct Answer & Explanation

. Revision to a long fully porous-coated cementless stem

Explanation

This describes a Vancouver B2 periprosthetic fracture (fracture around a loose stem with adequate bone stock). The standard of care is revision to a longer, cementless diaphyseal-engaging stem that bypasses the fracture by at least two cortical diameters.

Question 6708

Topic: 2. Trauma

A 75-year-old woman sustained a fall 8 years post-THA. Radiographs show a periprosthetic fracture around the stem tip. The stem is loose, but the proximal femur has adequate bone stock. What is the standard surgical management?

. Open reduction and internal fixation with cables and plate
. Trochanteric repair with claw plate
. Revision to a long porous-coated stem bypassing the fracture
. Revision with a proximal femoral replacement
. Conservative management in a spica cast

Correct Answer & Explanation

. Revision to a long porous-coated stem bypassing the fracture

Explanation

A periprosthetic fracture with a loose stem and adequate bone stock is a Vancouver B2 fracture. The standard of care is revision arthroplasty using a long stem that bypasses the fracture by at least two cortical diameters.

Question 6709

Topic: Lower Extremity Trauma

During a TKA for a patient with a 30-degree flexion contracture, the surgeon balances the flexion gap appropriately but finds the knee remains tight in extension despite adequate posterior capsular release. What is the most appropriate next step?

. Resect additional proximal tibia
. Resect additional distal femur
. Downsize the femoral component
. Upsize the femoral component
. Recut the anterior femur

Correct Answer & Explanation

. Resect additional distal femur

Explanation

A knee that is tight in extension but balanced in flexion requires enlargement of the extension gap only. Resecting additional distal femur achieves this isolated increase without altering the flexion gap.

Question 6710

Topic: Lower Extremity Trauma

The bending stiffness of a solid titanium intramedullary nail is proportional to its radius raised to which power?

. Second
. Third
. Fourth
. Fifth
. Sixth

Correct Answer & Explanation

. Fourth

Explanation

The area moment of inertia for a solid cylinder, which governs its resistance to bending (bending stiffness), is proportional to the radius to the fourth power (r^4). Therefore, even a small increase in nail diameter drastically increases its stiffness.

Question 6711

Topic: Lower Extremity Trauma

According to biomechanical principles, the bending rigidity of a solid cylindrical intramedullary nail is directly proportional to which of the following?

. Radius squared
. Radius cubed
. Radius to the fourth power
. Cross-sectional area
. Length of the nail squared

Correct Answer & Explanation

. Radius to the fourth power

Explanation

The bending rigidity of a solid cylindrical structure is proportional to the area moment of inertia, which scales with the radius to the fourth power (r^4). Therefore, a small increase in the nail's radius significantly increases its resistance to bending.

Question 6712

Topic: 2. Trauma

A patient with chronic kidney disease presents with a pathologic fracture. Laboratory tests show hypocalcemia and hyperphosphatemia. A deficiency in which specific renal enzyme contributes most directly to this altered bone mineral homeostasis?

. 25-hydroxylase
. 1-alpha-hydroxylase
. 24-hydroxylase
. Alkaline phosphatase
. Farnesyl pyrophosphate synthase

Correct Answer & Explanation

. 1-alpha-hydroxylase

Explanation

The kidneys produce 1-alpha-hydroxylase, which converts inactive 25-hydroxyvitamin D into the active 1,25-dihydroxyvitamin D. Deficiency in chronic kidney disease leads to decreased intestinal calcium absorption and secondary hyperparathyroidism.

Question 6713

Topic: 2. Trauma

In locked plating constructs used for bridge plating of comminuted diaphyseal fractures, increasing the "working length" of the plate has what primary biomechanical effect?

. Decreases the construct flexibility
. Increases the stress on the innermost screws
. Increases the overall construct stiffness
. Decreases the overall construct stiffness allowing for more interfragmentary motion
. Prevents secondary bone healing

Correct Answer & Explanation

. Decreases the overall construct stiffness allowing for more interfragmentary motion

Explanation

The working length of a plate is the distance between the two closest screws on either side of the fracture. Increasing this distance decreases the stiffness of the construct, allowing for more elastic deformation and promoting secondary bone healing.

Question 6714

Topic: 2. Trauma

Consider the biomechanical principles of fracture fixation shown in typical mechanical testing scenarios

. When utilizing a locked plating construct compared to conventional non-locked plating, which of the following best describes the structural mechanism of the locked construct?

. It relies on friction between the plate and bone for stability
. It acts as a single-beam construct preventing independent screw toggle
. It significantly increases compressive forces at the fracture site
. It requires perfect contouring to the bone surface to maintain alignment
. It decreases the area moment of inertia of the construct

Correct Answer & Explanation

. It acts as a single-beam construct preventing independent screw toggle

Explanation

Locked plating systems function as fixed-angle constructs, creating a single-beam mechanism where screws lock directly into the plate, eliminating toggle. This provides stability independent of bone-plate friction and does not require perfect contouring.

Question 6715

Topic: Lower Extremity Trauma

When comparing a slotted (open-section) intramedullary nail to an unslotted (closed-section) intramedullary nail of the same diameter and wall thickness, what is the primary biomechanical consequence of the slot?

. Slotting increases torsional rigidity
. Slotting decreases bending rigidity but not torsional rigidity
. Slotting decreases torsional rigidity significantly
. Slotting has no effect on torsional rigidity
. Slotting increases both bending and torsional rigidity

Correct Answer & Explanation

. Slotting decreases torsional rigidity significantly

Explanation

A closed-section (unslotted) tube has a much higher polar moment of inertia compared to an open-section (slotted) tube. Therefore, slotting significantly decreases the torsional rigidity of an intramedullary nail.

Question 6716

Topic: Lower Extremity Trauma

A solid cylindrical intramedullary nail's resistance to bending is proportional to its area moment of inertia. If the radius of the nail is doubled, its bending stiffness increases by a factor of:

. 2
. 4
. 8
. 16
. 32

Correct Answer & Explanation

. 16

Explanation

The area moment of inertia for a solid cylinder is proportional to the radius to the fourth power (r^4). Therefore, doubling the radius increases bending stiffness by a factor of 2^4 = 16.

Question 6717

Topic: 2. Trauma

The "working length" of a screw used in orthopaedic fracture fixation is defined as:

. The total length of the screw
. The distance from the screw head to the first engaged thread
. The length of bone engaged by the threads
. The distance between the screw head and the fracture site
. The distance from the head to the distal cortex

Correct Answer & Explanation

. The length of bone engaged by the threads

Explanation

The working length of a screw is the length of bone specifically engaged by the screw threads. For a plate, working length is the distance between the two closest fixation points on either side of the fracture.

Question 6718

Topic: 2. Trauma

Decreasing the distance between the two innermost screws (closest to the fracture site) in a plate-and-screw construct for a diaphyseal fracture will have which of the following biomechanical effects?

. Increase the working length and decrease construct stiffness
. Increase the working length and increase construct stiffness
. Decrease the working length and increase construct stiffness
. Decrease the working length and decrease construct stiffness
. Have no effect on working length or stiffness

Correct Answer & Explanation

. Decrease the working length and increase construct stiffness

Explanation

Working length is defined as the distance between the two nearest fixation points on opposite sides of the fracture. Decreasing the working length restricts motion at the fracture site, thereby increasing the overall stiffness of the construct.

Question 6719

Topic: 2. Trauma

For a tension band construct to be effective in treating a transverse patella fracture, the implant must convert tensile forces at the anterior surface into which of the following forces at the articular surface?

. Shear forces
. Torsional forces
. Compressive forces
. Bending forces
. Distraction forces

Correct Answer & Explanation

. Compressive forces

Explanation

The tension band principle relies on placing a tension-absorbing device (like a wire) on the tension side of a fractured bone. During dynamic loading, the construct converts potentially distracting tensile forces into stabilizing compressive forces at the articular surface.

Question 6720

Topic: 2. Trauma

When applying a bridging plate to a comminuted diaphyseal femur fracture, the surgeon decides to increase the working length of the plate. What biomechanical effect does this have on the construct?

. Increases the torsional stiffness
. Decreases the bending stiffness
. Increases the risk of plate failure due to stress shielding
. Decreases the axial strain at the fracture site
. Increases the pullout strength of the screws

Correct Answer & Explanation

. Decreases the bending stiffness

Explanation

The working length of a plate is the distance between the two closest screws on either side of the fracture. Increasing the working length decreases the bending stiffness of the construct, which allows for more interfragmentary motion and promotes secondary bone healing.

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