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2. Trauma MCQs

Practice Set 563 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 11241

Topic: 2. Trauma
During resuscitation of a polytraumatized patient with severe pelvic and lower extremity crush injuries, a Massive Transfusion Protocol (MTP) is initiated. Based on current trauma guidelines, what is the optimal ratio of packed red blood cells (PRBCs) to fresh frozen plasma (FFP) to platelets to improve early survival?
. 1:1:1
. 2:1:1
. 3:1:1
. 1:2:2
. 4:1:1

Correct Answer & Explanation

. 1:1:1

Explanation

The PROPPR trial demonstrated that a 1:1:1 ratio of PRBCs to FFP to platelets results in improved early hemostasis and reduces mortality from exsanguination. This ratio most closely mimics whole blood and mitigates trauma-induced coagulopathy.

Question 11242

Topic: Pelvic & Acetabular Trauma

A 35-year-old male arrives after a severe crush injury with a blood pressure of 75 mmHg and a heart rate of 135 bpm. Pelvic radiographs show a displaced vertical shear pelvic fracture. A pelvic binder is applied, and uncrossmatched blood is transfused, but his hemodynamics do not improve. The FAST exam is negative. What is the most appropriate next step?

. Exploratory laparotomy
. Application of a supra-acetabular external fixator
. Computed tomography (CT) of the abdomen and pelvis
. Retroperitoneal pelvic packing or pelvic angiography
. Administration of intravenous tranexamic acid and observation

Correct Answer & Explanation

. Exploratory laparotomy

Explanation

In a hemodynamically unstable patient with a pelvic ring injury and a negative FAST (ruling out major intra-abdominal hemorrhage), the pelvic retroperitoneum is the primary source of bleeding. Emergent retroperitoneal pelvic packing or angiography with embolization is indicated.

Question 11243

Topic: 2. Trauma

A 24-year-old male sustains a closed comminuted femur fracture. Thirty-six hours after admission, he develops acute respiratory distress, confusion, and a petechial rash over his axillae and conjunctivae. Which of the following describes the underlying pathophysiology of this syndrome?

. Release of thromboplastin causing widespread intravascular coagulation
. Venous stasis and endothelial injury leading to deep vein thrombosis
. Mechanical obstruction of pulmonary microvasculature by marrow fat droplets and biochemical damage from free fatty acids
. Immune complex deposition in the pulmonary capillaries
. Systemic release of myoglobin leading to acute tubular necrosis

Correct Answer & Explanation

. Release of thromboplastin causing widespread intravascular coagulation

Explanation

Fat Embolism Syndrome (FES) presents with a classic triad of hypoxemia, neurological abnormalities, and petechial rash. It is caused by marrow fat entering venous circulation, causing mechanical microvascular obstruction and a toxic biochemical cascade from free fatty acids.

Question 11244

Topic: 2. Trauma

A 30-year-old male sustains a low-velocity gunshot wound to the right leg. Radiographs reveal a non-displaced midshaft tibia fracture. There is a clean entrance wound, no exit wound, and the bullet is not intracapsular. The neurovascular examination is intact. What is the standard of care?

. Immediate surgical debridement of the bullet track and intramedullary nailing
. External fixation application
. Intravenous antibiotics for 7 days, leaving the bullet in situ
. Local wound care, tetanus prophylaxis, and immobilization
. Immediate removal of the bullet to prevent lead toxicity

Correct Answer & Explanation

. Immediate surgical debridement of the bullet track and intramedullary nailing

Explanation

Low-velocity gunshot wounds resulting in non-displaced fractures with minimal soft-tissue damage can generally be treated like closed fractures. Management includes local wound care, tetanus prophylaxis, a short course of oral antibiotics, and appropriate splinting.

Question 11245

Topic: 2. Trauma

An orthopedic researcher conducts a randomized controlled trial comparing two different types of intramedullary nails for tibial shaft fractures. The study finds no statistically significant difference in union rates (p = 0.12). However, a true difference does exist in the general population. Which of the following best describes this statistical scenario?

. Type I error
. Type II error
. Confounding bias
. Alpha error
. Selection bias

Correct Answer & Explanation

. Type I error

Explanation

A Type II error (beta error) occurs when a study fails to reject a false null hypothesis—meaning it finds no significant difference when one truly exists in nature. Statistical Power (1 - beta) is the probability of avoiding a Type II error, often due to an inadequately small sample size.

Question 11246

Topic: 2. Trauma

An orthopedic surgeon is selecting an intramedullary nail for a femur fracture. If the surgeon chooses a solid titanium nail with a radius of 12 mm instead of a 10 mm nail of the identical material, by approximately what factor does the bending rigidity increase?

. 1.2
. 1.44
. 1.72
. 2.07
. 2.44

Correct Answer & Explanation

. 1.2

Explanation

The bending rigidity of a solid cylinder is proportional to the area moment of inertia, which is proportional to the radius to the fourth power (r^4). (12/10)^4 = (1.2)^4 = 2.0736. Therefore, the bending rigidity increases by a factor of approximately 2.07.

Question 11247

Topic: 2. Trauma

Following an acute diaphyseal fracture, a hematoma forms and an inflammatory cascade is initiated. Experimental depletion of which of the following immune cell populations has been shown to completely halt the transition from the inflammatory phase to the cartilaginous reparative phase of fracture healing?

. T-lymphocytes
. B-lymphocytes
. Neutrophils
. Macrophages
. Eosinophils

Correct Answer & Explanation

. T-lymphocytes

Explanation

Macrophages (particularly the transition from M1 pro-inflammatory to M2 anti-inflammatory phenotypes) are absolutely critical for fracture healing. Studies have shown that experimental depletion of macrophages disrupts the formation of the cartilaginous callus and arrests fracture healing in the inflammatory phase.

Question 11248

Topic: 2. Trauma

Which of the following construct modifications will most effectively decrease construct stiffness and promote secondary bone healing via callus formation in a comminuted diaphyseal fracture treated with a locked plate?

. Decreasing the working length of the plate
. Using a titanium plate instead of a stainless steel plate of the same dimensions
. Increasing the number of screws placed near the fracture site
. Applying interfragmentary lag screws across the fracture fragments
. Using a thicker, broader stainless steel plate

Correct Answer & Explanation

. Decreasing the working length of the plate

Explanation

Using a titanium plate decreases construct stiffness compared to stainless steel due to titanium's lower modulus of elasticity. Decreasing the working length or adding more screws near the fracture site would inappropriately increase construct stiffness.

Question 11249

Topic: 2. Trauma

When utilizing a bridge plate technique for a comminuted diaphyseal femur fracture, how does increasing the working length of the plate affect the construct's biomechanics?

. Decreases the bending stiffness
. Increases the torsional stiffness
. Decreases the risk of implant failure by fatigue
. Increases the rigid anatomical fixation
. Decreases the stress concentrated on the screw-bone interface

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, allowing more flexible fixation that promotes secondary bone healing via callus formation.

Question 11250

Topic: 2. Trauma

Consider the structural principles of internal fixation.

According to the area moment of inertia for a rectangular fracture plate, the bending stiffness of the plate is most exponentially sensitive to changes in which of its dimensions?

. Length of the plate
. Width of the plate
. Thickness of the plate
. Working distance between the innermost screws
. Core diameter of the screw holes

Correct Answer & Explanation

. Length of the plate

Explanation

The area moment of inertia (I) for a rectangular cross-section is defined by the formula I = (width * thickness^3) / 12. Because the thickness variable is cubed, a small change in the thickness of the plate has the most profound (exponential) effect on its bending stiffness. The width only affects stiffness linearly.

Question 11251

Topic: Lower Extremity Trauma

Review the basic principles of intramedullary nail biomechanics.

The torsional rigidity of a solid cylindrical intramedullary nail is proportional to its radius raised to which power?

. Radius squared (r^2)
. Radius cubed (r^3)
. Radius to the fourth power (r^4)
. Radius to the fifth power (r^5)
. Inversely proportional to radius squared

Correct Answer & Explanation

. Radius squared (r^2)

Explanation

The torsional rigidity of a solid cylinder is directly proportional to the polar area moment of inertia, which mathematically correlates to the radius raised to the fourth power (r^4). Thus, a small increase in nail diameter massively increases torsional stiffness.

Question 11252

Topic: 2. Trauma

Which of the following mechanical conditions is an absolute prerequisite for primary (direct) bone healing to occur across a fracture site?

. Interfragmentary motion between 2% and 10%
. Absolute stability with interfragmentary strain < 2%
. Presence of a cartilaginous callus
. Intramedullary reaming to stimulate endosteal blood flow
. Cyclic axial loading to promote micromotion

Correct Answer & Explanation

. Interfragmentary motion between 2% and 10%

Explanation

Primary (direct) bone healing occurs via cutting cones crossing the fracture site without intermediate callus formation. It requires absolute mechanical stability (interfragmentary strain < 2%) and anatomic reduction.

Question 11253

Topic: 2. Trauma

Which of the following best defines the 'working length' of an interlocking intramedullary nail used for fracture fixation?

. The distance from the entry portal to the fracture site
. The overall length of the intramedullary nail
. The distance between the most proximal and most distal locking screws
. The distance between the locking screws nearest to the fracture on either side
. The length of the nail that matches the patient's medullary canal isthmus

Correct Answer & Explanation

. The distance from the entry portal to the fracture site

Explanation

In fracture fixation using an intramedullary nail (or a plate), the 'working length' is defined as the distance between the two closest points of fixation spanning the fracture. For an intramedullary nail, it is the distance between the closest proximal locking screw and the closest distal locking screw relative to the fracture site. A longer working length decreases the stiffness of the construct.

Question 11254

Topic: 2. Trauma

When utilizing a locking compression plate (LCP) as a bridging construct for a highly comminuted diaphyseal fracture, which of the following technical modifications will decrease construct stiffness to optimally promote secondary bone healing via callus formation?

. Decreasing the plate working length
. Placing screws in the holes immediately adjacent to the fracture gap
. Increasing the plate working length by leaving holes empty near the fracture
. Using a thicker and stiffer plate material such as cobalt-chromium
. Filling every available plate hole with bicortical locking screws

Correct Answer & Explanation

. Decreasing the plate working length

Explanation

In a bridge plating construct, secondary bone healing requires a controlled amount of interfragmentary micromotion to stimulate callus. Increasing the 'working length' (the distance between the two innermost screws on either side of the fracture) decreases the overall stiffness of the construct, allowing for this necessary micromotion.

Question 11255

Topic: 2. Trauma
Figures 1 through 4 are the injury radiographs and postsurgical open treatment radiographs of a 13-year-old girl who fell while on a trampoline and sustained an injury to her right-dominant elbow. The skin is closed and she has normal vascular and neurologic examination findings. Which complication most likely could occur as a result of this injury and treatment?
. Compartment syndrome
. Loss of elbow motion
. Avascular necrosis (AVN) of the radial head
. Nonunion of the fracture site

Correct Answer & Explanation

. Loss of elbow motion

Explanation

This girl sustained a fracture dislocation of the elbow with a severely displaced and rotated radial neck fracture. Required treatment was open reduction and internal fixation (ORIF). Complications following ORIF of radial neck fractures in children include posterior interosseous neuropraxia, valgus angulation, premature closure of the radial head physis, AVN of the radial head, nonunion, and elbow stiffness. Stiffness is most common.

Question 11256

Topic: 2. Trauma

Which of the following may be beneficial in decreasing the deleterious effects of total muscle ischemia in a patient who has a compartment syndrome:

. Systemic steroids
. Hypothermia
. Elevation of the extremity above the heart
. Antihypertensive therapy
. Anticoagulant therapy

Correct Answer & Explanation

. Systemic steroids

Explanation

Aside from performing a fasciotomy, little can be done for patients with a compartment syndrome. Hypothermia, systemic corticosteroids, and anticoagulation therapy may increase muscle tolerance to ischemia.Steroids and anticoagulation are not reasonable options because there is an impaired blood supply to the muscle (ie, these agents cannot enter the muscle). Hypothermia can be used to gain some time if immediate fasciotomy cannot be performed.

Question 11257

Topic: 2. Trauma
A 20-year-old male military recruit reports a 5-day history of progressive deep groin pain that is made worse with weight-bearing activities and running. His initial coronal T2-weighted MRI scan is shown in Figure 75. His initial treatment should consist of which of the following?
. Bed rest with skeletal traction (distal femur traction pin)
. Calcium supplements
. Crutches with protected weight bearing
. Open reduction and internal fixation
. Pulsed ultrasound treatment

Correct Answer & Explanation

. Crutches with protected weight bearing

Explanation

The MRI scan findings and patient history demonstrate a compression-sided femoral neck stress fracture. The most appropriate initial treatment is protected weight bearing, with close examination and imaging follow-up.

Question 11258

Topic: 2. Trauma

Figures A and B are radiographic images of an 85-year-old woman with isolated left hip pain. She describes a non-syncopal fall from standing 4 hours ago. Physical examination reveals pain with log-rolling the left thigh and the inability to bear weight on the affected leg. The radiologist reports no fracture in the left hip. What would be the next best step?


. Stress view radiographs of the left hip
. Non-weight bearing and pelvic bone scan in 7 days
. Non-weight bearing and repeat the CT scan after 48 hours from injury
. MRI hip and pelvis
. Weight bearing activity as tolerated with close follow-up

Correct Answer & Explanation

. Stress view radiographs of the left hip

Explanation

The next best step would be an MRI hip and pelvis to investigate for an occult fracture of the left hip.Moderate evidence supports MRI as the advanced imaging of choice for diagnosis of presumed hip fracture not apparent on initial radiographs. MRI has been shown to be able to detect occult fractures earlier than bone scan, with better spatial resolution. Usually the MRI should be obtained in less than 24 hours from the time of injury. For situations in which MRI is not immediately available, bone scan can be considered after 72 hours form the time of injury. However, this may compromise patient care and put the patient at risk of fracture displacement.Cannon et al. reviewed the imaging of choice in occult hip fracture. They showed that physical examination yields a poor sensitivity identifying occult hip fractures, with log-rolling and straight-leg raise as 50% and 70%, respectively. The most sensitive modality for occult fracture identification was MRI.Iwata et al. retrospectively reviewed a cohort of 35 patients with clinically suspected fractures of the hip that underwent MRI. All radiographs werenegative. In 26 of these patients, a T1-weighted coronal MRI showed a hip fracture with 100% sensitivity.Roberts et al. reviewed the 2015 AAOS Clinical Practice Guideline: Management of Hip Fractures in the Elderly. They report moderate evidence that supports MRI as the advanced imaging of choice for diagnosis of presumed hip fractures not apparent on initial radiographs.Figure A is a AP radiograph of the left hip and pelvis. Apart from a healed fracture of the ischiopubic rami and generalized osteopenia, there is no obvious hip fracture. Figure B is a coronal CT image that does not demonstrate evidence of an acute hip fracture. Illustration A is a T1 weighted MR image that shows a non displaced fracture (white arrow) through the intertrochanteric region of the left proximal femur.Incorrect Answers:Answer 1: Stress view radiographs would not be recommended.Answer 2: If MRI is contraindicated, for example if a pacemaker is present, then a bone scan at 72 hours is the next test of choice. Waiting 7 days would not be appropriate for this patient.Answer 3: Repeating the CT scan will not help to identify fracture, unless the fracture becomes displaced. A delay in identifying a fracture pattern by 48 hours, while the patient is non-mobile, significantly increases their risk of complications.Answer 5: Weight bearing activity as tolerated with close follow-up may be suggested if the patient is clinically able to walk and advanced imaging is negative for fracture. The best modality to rule-out occult fracture is MRI.

Question 11259

Topic: 2. Trauma

What is the most common complication following open reduction locking plate osteosynthesis of this injury?

. Intra-articular screw penetration
. Posttraumatic avascular necrosis (AVN)
. Nonunion
. Subacromial plate impingement

Correct Answer & Explanation

. Intra-articular screw penetration

Explanation

- Intra-articular screw penetration_

Question 11260

Topic: 2. Trauma
Which of the following stress fractures is the most prone to nonunion and requires surgical intervention?
. Proximal posteromedial compression
. Distal posteromedial compression
. Anterior tibial cortex tension
. Femoral shaft compression
. Medial malleolus

Correct Answer & Explanation

. Anterior tibial cortex tension

Explanation

The majority of stress fractures are treated with rest and protected weight-bearing. When the patient rests, strain on the affected bone is reduced and formation exceeds resorption, leading to bone healing. An anterior tibial tension stress fracture is most prone to not healing. This fracture typically occurs in the anterior cortex and appears as a horizontal lucency—the dreaded black line. Many patients with this fracture will not heal nonoperatively and will require intramedullary rod fixation.

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