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2. Trauma MCQs

Practice Set 506 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 10101

Topic: Lower Extremity Trauma

What is the primary function of the menisci in the knee joint?

. Initiate knee flexion
. Provide varus and valgus stability
. Increase articular congruence and distribute loads
. Synthesize synovial fluid
. Act as a direct attachment point for the quadriceps

Correct Answer & Explanation

. Increase articular congruence and distribute loads

Explanation

The menisci (medial and lateral) are C-shaped fibrocartilaginous structures that primarily increase the contact area between the femoral condyles and tibial plateau, thereby improving articular congruence and distributing compressive loads across the knee joint. They also play a role in shock absorption, joint lubrication, and stability, but load distribution and congruence are their main biomechanical functions. They do not initiate flexion, provide primary collateral stability (that's ligaments), synthesize synovial fluid (that's the synovium), or act as direct attachment points for the quadriceps (that's the patella and patellar tendon).

Question 10102

Topic: 2. Trauma

Regarding compartment syndrome of the forearm, which of the following is the most reliable clinical sign?

. Pallor
. Pulselessness
. Paralysis
. Paresthesia
. Pain out of proportion to injury

Correct Answer & Explanation

. Pain out of proportion to injury

Explanation

The '6 Ps' are commonly taught for compartment syndrome (Pain, Pallor, Pulselessness, Paresthesia, Paralysis, Poikilothermia). However, pain out of proportion to injury, especially pain with passive stretching of the muscles in the affected compartment, is generally considered the earliest and most reliable clinical sign. Pallor, pulselessness, and paralysis are late signs, indicating severe ischemia, and often portend poor outcomes.

Question 10103

Topic: 2. Trauma

Which type of orthopaedic implant is typically used for compression osteosynthesis in diaphyseal long bone fractures?

. Intramedullary nail
. External fixator
. Locking plate
. Dynamic Compression Plate (DCP)
. K-wires

Correct Answer & Explanation

. Dynamic Compression Plate (DCP)

Explanation

A Dynamic Compression Plate (DCP) is specifically designed to achieve interfragmentary compression across a fracture site by eccentric screw placement, which then allows the plate to pull the fragments together as screws are tightened. Intramedullary nails provide load-sharing internal fixation. External fixators are typically temporary. Locking plates provide angular stability but are not primarily designed for compression osteosynthesis. K-wires provide temporary fixation.

Question 10104

Topic: 2. Trauma

What is the most common cause of non-union in long bone fractures?

. Excessive rigid fixation
. Insufficient blood supply to the fracture fragments
. Early weight-bearing
. Systemic antibiotic use
. Patient age

Correct Answer & Explanation

. Insufficient blood supply to the fracture fragments

Explanation

Insufficient blood supply to the fracture fragments (avascularity) is the most common and critical factor leading to non-union, especially in specific fracture sites like the femoral neck, scaphoid, or talar neck. Other factors like infection, inadequate immobilization, interposition of soft tissue, and metabolic factors also play a role, but vascularity is paramount. Excessive rigid fixation can lead to stress shielding, and early weight-bearing can cause instability, but avascularity is the primary biological reason for non-union.

Question 10105

Topic: 2. Trauma

Which of the following structures is most commonly injured in a 'terrible triad' injury of the elbow?

. Radial head fracture, coronoid fracture, ulnar collateral ligament rupture
. Olecranon fracture, coronoid fracture, radial collateral ligament rupture
. Radial head fracture, olecranon fracture, medial epicondyle fracture
. Distal humerus fracture, radial head fracture, ulnar collateral ligament rupture
. Coronoid fracture, capitellum fracture, annular ligament rupture

Correct Answer & Explanation

. Radial head fracture, coronoid fracture, ulnar collateral ligament rupture

Explanation

The 'terrible triad' of the elbow consists of a radial head fracture, a coronoid process fracture, and a rupture of the ulnar collateral ligament (medial collateral ligament of the elbow). This combination often leads to elbow instability and requires operative management.

Question 10106

Topic: 2. Trauma

Which of the following is considered the earliest and most reliable clinical sign of acute compartment syndrome in an awake, alert patient?

. Loss of palpable distal pulses
. Pallor of the distal extremity
. Paresis of the affected muscles
. Pain with passive stretch of the involved muscles
. Decreased capillary refill time

Correct Answer & Explanation

. Pain with passive stretch of the involved muscles

Explanation

Pain out of proportion to the injury and pain with passive stretch of the muscles in the involved compartment are the earliest and most sensitive clinical indicators of compartment syndrome. Pulselessness, pallor, and paralysis are late signs indicating irreversible ischemic damage.

Question 10107

Topic: Lower Extremity Trauma

According to the mechanical principles of intramedullary fixation, the bending stiffness of a solid cylindrical titanium intramedullary nail is proportional to its radius raised to which power?

. Radius (r^1)
. Radius squared (r^2)
. Radius cubed (r^3)
. Radius to the fourth power (r^4)
. Radius to the fifth power (r^5)

Correct Answer & Explanation

. Radius to the fourth power (r^4)

Explanation

The bending stiffness (area moment of inertia) of a solid cylinder is proportional to the radius to the fourth power (r^4). Torsional stiffness (polar moment of inertia) is also proportional to r^4. This means that even a small increase in the diameter of an intramedullary nail significantly increases its stiffness.

Question 10108

Topic: 2. Trauma
A 24-year-old polytrauma patient arrives in the emergency department with a heart rate of 130 bpm, decreased pulse pressure, confusion, and a urine output of 10 mL/hr. According to the ATLS classification of hemorrhagic shock, what estimated percentage of blood volume has this patient lost (Class III shock)?
. Up to 15%
. 15% to 30%
. 31% to 40%
. 41% to 50%
. Greater than 50%

Correct Answer & Explanation

. 31% to 40%

Explanation

This patient exhibits signs of Class III hemorrhagic shock (tachycardia >120, decreased blood pressure/pulse pressure, confusion, decreased urine output). Class III shock corresponds to a blood volume loss of 31-40% (approx. 1500-2000 mL in an adult). Class I is up to 15%; Class II is 15-30%; Class IV is >40%.

Question 10109

Topic: 2. Trauma
A 45-year-old male presents with a comminuted open tibial fracture (Gustilo-Anderson Type IIIB) after a high-energy motor vehicle accident. Twelve hours post-debridement and external fixation, he develops a fever of 39.2°C, heart rate 115 bpm, respiratory rate 28 bpm, and WBC count 14,000/µL. His blood pressure is 100/60 mmHg. Which of the following criteria is not met for a diagnosis of Systemic Inflammatory Response Syndrome (SIRS) in this patient?
. Temperature >38°C or <36°C
. Heart rate >90 bpm
. Respiratory rate >20 bpm or PaCO2 <32 mmHg
. WBC count >12,000/µL or <4,000/µL or >10% immature forms
. All criteria for SIRS are met

Correct Answer & Explanation

. All criteria for SIRS are met

Explanation

This patient meets all four criteria for SIRS: Temperature (39.2°C > 38°C), Heart Rate (115 bpm > 90 bpm), Respiratory Rate (28 bpm > 20 bpm), and WBC count (14,000/µL > 12,000/µL). The question asks which criterion is not met. Since all are met, the correct answer is that 'All criteria for SIRS are met'.

Question 10110

Topic: 2. Trauma

Regarding the pathophysiology of 'gut-derived infection' or bacterial translocation, a significant contributor to sepsis in severe orthopedic trauma patients, which of the following is the primary mechanism?

. Increased enterohepatic recirculation of toxins
. Enhanced gut motility leading to bacterial dissemination
. Loss of intestinal barrier integrity allowing microbes and endotoxins to enter systemic circulation
. Decreased production of gastric acid facilitating bacterial overgrowth
. Direct hematogenous spread from localized bowel injury

Correct Answer & Explanation

. Loss of intestinal barrier integrity allowing microbes and endotoxins to enter systemic circulation

Explanation

Gut-derived infection, or bacterial translocation, occurs when the intestinal mucosal barrier is compromised, typically due to hypoperfusion, ischemia-reperfusion injury, and inflammatory responses seen in severe trauma or shock. This loss of 'gut barrier function' allows commensal bacteria and their endotoxins (e.g., LPS from gram-negative bacteria) to translocate from the intestinal lumen into the mesenteric lymphatics, portal circulation, and eventually the systemic circulation, leading to systemic infection and inflammation. Options such as enhanced gut motility or decreased gastric acid are secondary or less direct primary mechanisms compared to the fundamental breakdown of the mucosal barrier.

Question 10111

Topic: 2. Trauma

Which of the following is considered the most appropriate initial fluid resuscitation strategy for a 60-year-old male with severe sepsis following open reduction internal fixation of a femoral fracture, presenting with hypotension (MAP 55 mmHg) and lactate 4.5 mmol/L?

. Albumin 5% at 50 mL/kg over 6 hours
. Normal saline 500 mL bolus over 15 minutes, then reassess
. Lactated Ringer's solution 30 mL/kg intravenously over the first 3 hours
. Dextrose 5% in water at 100 mL/hour to maintain urine output
. Start vasopressors immediately without fluid administration

Correct Answer & Explanation

. Lactated Ringer's solution 30 mL/kg intravenously over the first 3 hours

Explanation

The Surviving Sepsis Campaign guidelines recommend a rapid administration of 30 mL/kg of intravenous crystalloid fluid within the first 3 hours for patients with sepsis-induced hypoperfusion (e.g., hypotension, elevated lactate). Lactated Ringer's is a balanced crystalloid often preferred over normal saline due to concerns about hyperchloremic acidosis with large volumes of normal saline. Option B is too small and slow; option A (albumin) is typically reserved for patients requiring substantial amounts of crystalloids; option D is insufficient; option E is premature without initial fluid resuscitation unless profound shock is unresponsive to even initial boluses.

Question 10112

Topic: 2. Trauma
A 28-year-old sustained a calcaneal fracture with significant soft tissue injury. He develops worsening pain, swelling, and fever on post-operative day 2. Which of the following findings would be most indicative of septic shock rather than severe sepsis?
. Serum lactate level of 3.5 mmol/L
. Mean Arterial Pressure (MAP) of 60 mmHg requiring vasopressors despite adequate fluid resuscitation
. Platelet count of 90,000/µL
. Acute Kidney Injury (AKI) with creatinine 2.5 mg/dL (baseline 0.9 mg/dL)
. Partial pressure of oxygen (PaO2)/fraction of inspired oxygen (FiO2) ratio of 250

Correct Answer & Explanation

. Mean Arterial Pressure (MAP) of 60 mmHg requiring vasopressors despite adequate fluid resuscitation

Explanation

Septic shock is defined by persistent hypotension requiring vasopressors to maintain MAP ≥65 mmHg and a serum lactate level >2 mmol/L despite adequate fluid resuscitation. While an elevated lactate (option A), thrombocytopenia (option C), AKI (option D), and ARDS (option E, PaO2/FiO2 <300) are all signs of organ dysfunction consistent with severe sepsis, only the combination of vasopressor requirement for hypotension AND elevated lactate after fluid resuscitation signifies septic shock.

Question 10113

Topic: 2. Trauma

Regarding the management of stress ulcers in critically ill orthopedic patients, particularly those with severe trauma or sepsis, which of the following is the most appropriate prophylactic measure?

. Routine administration of proton pump inhibitors (PPIs) to all hospitalized trauma patients
. Selective use of H2 receptor antagonists for patients with active GI bleeding history
. Enteral nutrition as early as possible to maintain gut mucosal integrity
. Administering corticosteroids to reduce inflammatory response
. Performing gastric lavage twice daily

Correct Answer & Explanation

. Enteral nutrition as early as possible to maintain gut mucosal integrity

Explanation

Early enteral nutrition is the preferred method for stress ulcer prophylaxis in critically ill patients, as it maintains gut mucosal integrity, promotes blood flow, and may prevent bacterial translocation. Pharmacological prophylaxis (PPIs or H2RAs) is recommended for patients with specific risk factors (e.g., mechanical ventilation >48h, coagulopathy, severe burns, head injury, history of GI bleed, multiple trauma, sepsis). Routine use for all trauma patients is not justified, and corticosteroids would increase risk, not decrease it. Gastric lavage is not a prophylactic measure.

Question 10114

Topic: 2. Trauma

Which of the following blood tests is most useful for early identification of sepsis and monitoring response to treatment, particularly in differentiating SIRS from infection in a complex orthopedic patient?

. C-reactive protein (CRP)
. Erythrocyte Sedimentation Rate (ESR)
. Procalcitonin (PCT)
. Lactate dehydrogenase (LDH)
. Serum amylase

Correct Answer & Explanation

. Procalcitonin (PCT)

Explanation

Procalcitonin (PCT) is generally considered the most specific and sensitive biomarker for bacterial infection and sepsis among the given options. Its levels rise rapidly in bacterial infections and correlate with severity, decreasing with effective treatment. CRP and ESR are less specific, as they are elevated in many inflammatory conditions (including post-operative inflammation, trauma, and non-infectious SIRS). LDH and amylase are markers for tissue injury or specific organ damage (pancreatitis), not primary sepsis markers.

Question 10115

Topic: 2. Trauma

A patient with a traumatic pelvic fracture and retroperitoneal hematoma develops abdominal distention, decreased urine output, and increasing ventilatory pressures. The intra-abdominal pressure (IAP) is measured at 22 mmHg. This clinical picture is most consistent with which complication, often seen in severe trauma and sepsis?

. Acute Respiratory Distress Syndrome (ARDS)
. Acute Kidney Injury (AKI)
. Abdominal Compartment Syndrome (ACS)
. Disseminated Intravascular Coagulation (DIC)
. Sepsis-induced cardiomyopathy

Correct Answer & Explanation

. Abdominal Compartment Syndrome (ACS)

Explanation

The patient's presentation of abdominal distention, decreased urine output (oliguria/AKI), and increasing ventilatory pressures (due to diaphragmatic splinting and reduced lung compliance) in the context of elevated intra-abdominal pressure (IAP > 20 mmHg) is highly characteristic of Abdominal Compartment Syndrome (ACS). This is a serious complication often seen in severe trauma, major abdominal surgery, and sepsis, which can exacerbate organ dysfunction (respiratory, renal, cardiovascular).

Question 10116

Topic: 2. Trauma
Which of the following best describes the utility of the SOFA (Sequential Organ Failure Assessment) score in orthopedic sepsis?
. It primarily assesses the risk of surgical site infection.
. It predicts the likelihood of prosthetic joint infection.
. It quantifies organ dysfunction in critically ill patients, useful for diagnosing sepsis.
. It measures the severity of pain in orthopedic trauma.
. It is used to grade the severity of open fractures.

Correct Answer & Explanation

. It quantifies organ dysfunction in critically ill patients, useful for diagnosing sepsis.

Explanation

The SOFA score is a widely used tool for quantifying the severity of organ dysfunction in critically ill patients. It assesses six organ systems (respiratory, cardiovascular, hepatic, coagulation, renal, and neurological). A change in SOFA score of ≥2 points from baseline, in the presence of infection, indicates sepsis. Therefore, it is crucial for both diagnosing sepsis and monitoring its progression and severity. It is not designed for assessing surgical site infection risk, prosthetic joint infection likelihood, pain severity, or open fracture grading.

Question 10117

Topic: 2. Trauma
Which of the following orthopedic conditions carries the highest risk for developing necrotizing fasciitis, a severe soft tissue infection that can rapidly lead to septic shock?
. Stable ankle fracture
. Elective knee arthroscopy
. Closed distal radius fracture
. Open Gustilo-Anderson Type IIIC tibial fracture with extensive soft tissue damage and contamination
. Rotator cuff repair

Correct Answer & Explanation

. Open Gustilo-Anderson Type IIIC tibial fracture with extensive soft tissue damage and contamination

Explanation

Necrotizing fasciitis is a rapidly progressing soft tissue infection characterized by extensive necrosis of fascia and subcutaneous tissue, often associated with severe systemic toxicity and high mortality. Open fractures, especially those with extensive soft tissue damage, high-energy trauma, and significant contamination (Type IIIC implies vascular injury requiring repair), provide an ideal environment for polymicrobial infection, impaired local immunity, and rapid spread, making them the highest risk among the options provided. The other options are typically lower risk for this specific, aggressive infection.

Question 10118

Topic: 2. Trauma

What is the primary mechanism by which sepsis can lead to acute respiratory distress syndrome (ARDS) in an orthopedic trauma patient?

. Direct bacterial infection of the lungs causing pneumonia
. Increased hydrostatic pressure from aggressive fluid resuscitation
. Systemic inflammatory mediators causing endothelial damage and increased permeability in the pulmonary capillaries
. Aspiration of gastric contents during intubation
. Pulmonary embolism from deep vein thrombosis

Correct Answer & Explanation

. Systemic inflammatory mediators causing endothelial damage and increased permeability in the pulmonary capillaries

Explanation

Sepsis-induced ARDS is primarily caused by the systemic inflammatory response. Inflammatory mediators (cytokines, chemokines) released during sepsis lead to widespread activation and damage of the pulmonary capillary endothelium and alveolar epithelium. This results in increased vascular permeability, leakage of protein-rich fluid into the alveolar space, loss of surfactant function, and impaired gas exchange, characteristic of ARDS. While the other options can contribute to respiratory issues, the systemic inflammatory damage to the lung endothelium is the defining mechanism of sepsis-induced ARDS.

Question 10119

Topic: 2. Trauma

The concept of 'gut-derived infection' is particularly relevant in severe orthopedic trauma patients because:

. Orthopedic procedures inherently increase the risk of bowel perforation.
. Immobilization post-trauma consistently leads to severe constipation.
. Severe trauma often causes splanchnic hypoperfusion, leading to intestinal barrier dysfunction and bacterial translocation.
. Most orthopedic surgical sites are colonized by gut flora.
. Antibiotic prophylaxis used in orthopedics disrupts normal gut microbiome leading to dysbiosis.

Correct Answer & Explanation

. Severe trauma often causes splanchnic hypoperfusion, leading to intestinal barrier dysfunction and bacterial translocation.

Explanation

Severe trauma, particularly high-energy orthopedic injuries, often leads to systemic shock, hypoperfusion, and activation of the inflammatory cascade. This results in decreased blood flow to the splanchnic (gut) circulation, causing ischemia-reperfusion injury to the intestinal mucosa. The compromised mucosal barrier then allows bacteria and endotoxins from the gut lumen to translocate into the systemic circulation, contributing significantly to SIRS and sepsis. While the other options might have some validity in specific cases, splanchnic hypoperfusion and subsequent barrier dysfunction is the core mechanism.

Question 10120

Topic: 2. Trauma

A patient with a traumatic brain injury and a femur fracture develops polyuria and hypernatremia in the context of sepsis. Which endocrine abnormality should be considered?

. Syndrome of Inappropriate Antidiuretic Hormone (SIADH)
. Adrenal insufficiency
. Diabetes insipidus
. Thyroid storm
. Hypoglycemia

Correct Answer & Explanation

. Diabetes insipidus

Explanation

Polyuria (excessive urine output) and hypernatremia, particularly in a patient with traumatic brain injury and sepsis, are classic signs of diabetes insipidus (DI). DI results from insufficient antidiuretic hormone (ADH) secretion (central DI) or renal insensitivity to ADH (nephrogenic DI), leading to excessive free water loss. SIADH would present with hyponatremia. Adrenal insufficiency might cause hypotension but not typically polyuria/hypernatremia. Thyroid storm and hypoglycemia are distinct endocrine disorders.

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