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2. Trauma MCQs

Practice Set 69 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 1361

Topic: 2. Trauma

A 68-year-old female with osteoporotic bone requires internal fixation for a distal femur fracture. To maximize the pull-out strength of the screws in this challenging bone quality, which of the following biomechanical principles should the surgeon prioritize?

. A. Increasing the core diameter of the screw.
. B. Decreasing the outer diameter of the screw.
. C. Increasing the thread density (finer pitch) of the screw.
. D. Reducing the number of threads engaged in the bone cortex.
. E. Utilizing a screw with a larger pilot hole.

Correct Answer & Explanation

. C. Increasing the thread density (finer pitch) of the screw.

Explanation

Correct Answer: CThe case states that pull-out strength can be increased by 'increasing thread density' or by having a 'finer' pitch, which allows more turns of the spiral thread to engage in a given depth of cortex, creating greater resistance to pull-out. Options A and B would decrease the contact surface area or thread depth, thereby reducing pull-out strength. Option D directly contradicts the principle of increasing engaged threads. Option E (larger pilot hole) is a surgeon factor that reduces pull-out strength.

Question 1362

Topic: 2. Trauma

During a complex ankle fracture fixation, a junior resident inadvertently makes a pilot hole slightly larger than recommended for the chosen screw. This technical error is most likely to result in which of the following?

. A. Increased screw torsional strength.
. B. Enhanced screw-bone interface compression.
. C. Reduced screw pull-out strength.
. D. Greater resistance to screw stripping.
. E. Improved screw insertion torque.

Correct Answer & Explanation

. C. Reduced screw pull-out strength.

Explanation

Correct Answer: CThe case explicitly lists 'making too large a pilot hole' as a surgeon factor that can reduce screw pull-out strength. A larger pilot hole reduces the contact area between the screw threads and the bone, diminishing the frictional and mechanical interlock necessary for strong fixation. Options A, B, D, and E are incorrect as a larger pilot hole would generally weaken the fixation, not strengthen it or improve insertion characteristics in a beneficial way.

Question 1363

Topic: 2. Trauma

A surgeon is selecting a screw for metaphyseal fixation in a comminuted proximal humerus fracture, where bone quality may be compromised. To optimize the screw's resistance to axial dislodgement, which characteristic related to the screw's thread design would be most beneficial?

. A. A larger lead.
. B. A coarser pitch.
. C. A finer pitch.
. D. A shallower thread depth.
. E. A smaller outer diameter.

Correct Answer & Explanation

. C. A finer pitch.

Explanation

Correct Answer: CThe case states, 'The 'finer' the pitch, the more turns of the spiral thread engage in a given depth of cortex, creating greater resistance to pull-out.' A finer pitch means more threads per unit length, increasing the contact surface area with the bone. A larger lead (A) or coarser pitch (B) would mean fewer threads engaged. A shallower thread depth (D) or smaller outer diameter (E) would reduce the contact surface area, thereby decreasing pull-out strength.

Question 1364

Topic: 2. Trauma

A 45-year-old male sustains a comminuted mid-shaft femoral fracture (OTA/AO 32-C3) in a high-energy trauma. He is hemodynamically stable. Which of the following is the most appropriate initial surgical approach concerning reaming?

. Immediate unreamed intramedullary nailing to minimize fat embolism risk.
. Staged reamed intramedullary nailing after damage control resuscitation.
. Immediate reamed intramedullary nailing to achieve superior biomechanical stability.
. Temporary external fixation followed by delayed reamed nailing in 10-14 days.
. Percutaneous plating for indirect reduction to preserve soft tissue.

Correct Answer & Explanation

. Immediate reamed intramedullary nailing to achieve superior biomechanical stability.

Explanation

Correct Answer: CFor a hemodynamically stable patient with a comminuted mid-shaft femoral fracture, immediate reamed intramedullary nailing is generally the preferred approach. Reaming clears the medullary canal, allowing for a larger diameter nail, which provides greater bending and torsional stiffness, leading to superior biomechanical stability and higher rates of union. While unreamed nailing might be considered in polytrauma patients who are unstable or have significant pulmonary compromise to reduce the risk of fat embolism, a stable patient benefits from reamed nailing. Staged procedures are often reserved for patients who are initially unstable. External fixation is typically a temporizing measure. Percutaneous plating is not the standard of care for a comminuted mid-shaft femoral fracture due to inferior load-sharing capabilities compared to IM nailing.

Question 1365

Topic: 2. Trauma

Regarding the entry point for an antegrade femoral intramedullary nail, which statement is most accurate to prevent iatrogenic injury?

. A piriformis fossa entry point minimizes avascular necrosis of the femoral head.
. A trochanteric tip entry point provides the best alignment for valgus fractures.
. A greater trochanteric entry point invariably requires a larger nail diameter.
. A piriformis fossa entry point is associated with a lower incidence of hip pain.
. A medial-based trochanteric entry point reduces the risk of iatrogenic fracture of the greater trochanter.

Correct Answer & Explanation

. A piriformis fossa entry point minimizes avascular necrosis of the femoral head.

Explanation

Correct Answer: AWhile both piriformis fossa and trochanteric entry points are utilized, the piriformis fossa entry point, when properly executed, is considered to minimize the risk of avascular necrosis of the femoral head by avoiding excessive penetration into the vascular watershed area of the superior retinacular vessels. However, it can be technically challenging and increase the risk of gluteal muscle damage. A trochanteric tip entry point may risk damage to the gluteus medius and piriformis tendons and can lead to lateral hip pain. A medial-based trochanteric entry point is more likely to cause iatrogenic fracture of the greater trochanter or varus malalignment due to impingement. The size of the nail is determined by the medullary canal, not the entry point directly. Hip pain is often multifactorial but can be higher with more lateral entry points.

Question 1366

Topic: 2. Trauma

What is the primary biomechanical advantage of reamed compared to unreamed intramedullary nailing for diaphyseal fractures?

. Increased intramedullary pressure, promoting callus formation.
. Ability to use a larger diameter nail, improving bending and torsional stiffness.
. Reduced risk of thermal necrosis to the endosteal blood supply.
. Faster insertion time, minimizing operating room exposure.
. Better preservation of existing endosteal vascularity due to less debris.

Correct Answer & Explanation

. Ability to use a larger diameter nail, improving bending and torsional stiffness.

Explanation

Correct Answer: BThe primary biomechanical advantage of reamed intramedullary nailing is the ability to use a larger diameter nail. This significantly increases the nail's moment of inertia, which dramatically improves its bending and torsional stiffness. This enhanced stability is crucial for fracture healing, especially in comminuted or unstable fractures. While reaming does increase intramedullary pressure and transiently disrupts the endosteal blood supply, the long-term benefit of superior stability often outweighs these initial concerns. Reduced thermal necrosis is incorrect, as reaming generates heat. Faster insertion time is not a primary biomechanical advantage, and reaming typically increases insertion time. Preservation of endosteal vascularity is generally better with unreamed nailing.

Question 1367

Topic: 2. Trauma
A 30-year-old male sustains an open Gustilo-Anderson Type IIIA tibia fracture. After debridement and irrigation, the most appropriate definitive fixation method is:
. External fixation followed by conversion to plate fixation.
. Immediate reamed intramedullary nailing.
. Delayed primary closure and casting.
. Immediate unreamed intramedullary nailing.
. Circular external fixation (Ilizarov) until union.

Correct Answer & Explanation

. Immediate unreamed intramedullary nailing.

Explanation

For open Gustilo-Anderson Type IIIA tibia fractures, immediate unreamed intramedullary nailing, after thorough debridement and irrigation, is generally considered the preferred definitive fixation method. Unreamed nailing reduces the theoretical risk of disseminating contaminants into the medullary canal compared to reamed nailing, while still providing stable fixation and promoting early weight-bearing.

Question 1368

Topic: 2. Trauma

Which of the following conditions is considered a relative contraindication to reamed intramedullary nailing?

. Age greater than 70 years.
. Significant obesity (BMI > 40).
. Active systemic infection unrelated to the fracture.
. Severe pulmonary compromise (e.g., ARDS).
. Polytrauma with ISS < 16.

Correct Answer & Explanation

. Severe pulmonary compromise (e.g., ARDS).

Explanation

Correct Answer: DSevere pulmonary compromise, such as Acute Respiratory Distress Syndrome (ARDS), is a relative contraindication to reamed intramedullary nailing. Reaming can lead to increased intramedullary pressure, release of fat emboli, and inflammatory mediators into the systemic circulation, which can exacerbate existing pulmonary issues. In such cases, unreamed nailing or external fixation might be preferred. Age and obesity are not contraindications per se, though they can pose technical challenges. Active systemic infection is generally a contraindication to any implant surgery. Polytrauma with an ISS < 16 is typically not a contraindication, and IM nailing is often beneficial in these patients.

Question 1369

Topic: 2. Trauma

A patient with a comminuted subtrochanteric femur fracture (AO/OTA 32-C1) is treated with a long cephalomedullary nail. Which reduction maneuver is often necessary to achieve adequate alignment before nail insertion?

. Maintenance of knee flexion to relax gastrocnemius.
. Application of external rotation to the distal fragment.
. Direct manipulation of the proximal fragment with a Schanz pin.
. Use of a femoral distractor to overcome adductor muscle spasm.
. Application of axial compression to the fracture site.

Correct Answer & Explanation

. Use of a femoral distractor to overcome adductor muscle spasm.

Explanation

Correct Answer: DSubtrochanteric fractures are notoriously difficult to reduce due to the strong deforming forces of the hip musculature (iliopsoas, gluteus medius/minimus, adductors). A femoral distractor or manual traction is often necessary to overcome the powerful adductor spasm and length discrepancy, allowing for proper reduction. Once length is restored, other maneuvers may be needed for rotational and angular control. Knee flexion is more relevant for distal femur fractures (gastrocsoleus pull). External rotation is often the deformity, so internal rotation may be needed. Direct manipulation with a Schanz pin can aid, but overcoming severe shortening/displacement usually requires traction first. Axial compression before achieving length and alignment is counterproductive.

Question 1370

Topic: 2. Trauma

What is the most common iatrogenic complication associated with a piriformis fossa entry point for femoral intramedullary nailing?

. Heterotopic ossification in the gluteal region.
. Avascular necrosis of the femoral head.
. Greater trochanteric fracture.
. Damage to the superior gluteal neurovascular bundle.
. Varus malunion due to medialization of the nail.

Correct Answer & Explanation

. Heterotopic ossification in the gluteal region.

Explanation

Correct Answer: AThe most common iatrogenic complication associated with a piriformis fossa entry point is postoperative hip pain, often attributed to gluteal tendon irritation or heterotopic ossification (HO) in the gluteal region. While avascular necrosis of the femoral head is a theoretical concern with excessive penetration or damage to the retinacular vessels, it is less common than hip pain/HO. Greater trochanteric fracture is more associated with a lateral entry point. Damage to the superior gluteal neurovascular bundle is possible but less frequent than HO. Varus malunion is more related to an excessively medial entry point or improper reduction, rather than the piriformis fossa specifically.

Question 1371

Topic: 2. Trauma

A patient undergoes IM nailing for a femoral shaft fracture. Postoperatively, they develop chest pain, dyspnea, and petechial rash. Which complication is most likely?

. Pulmonary embolism.
. Pneumonia.
. Fat embolism syndrome.
. Acute myocardial infarction.
. Adult Respiratory Distress Syndrome (ARDS).

Correct Answer & Explanation

. Fat embolism syndrome.

Explanation

Correct Answer: CThe classic triad of symptoms – respiratory distress, neurological dysfunction, and a petechial rash – following long bone fracture fixation (especially IM nailing) is highly indicative of Fat Embolism Syndrome (FES). The pathophysiology involves the release of marrow fat into the circulation, leading to mechanical obstruction and inflammatory response in the lungs and other organs. While pulmonary embolism is a possibility after any surgery, the presence of the petechial rash makes FES the more likely diagnosis. Pneumonia and AMI would present differently, and ARDS is a potential severe manifestation of FES but FES is the primary diagnosis here.

Question 1372

Topic: 2. Trauma

A 35-year-old male sustained a midshaft clavicle fracture 6 months ago, treated non-operatively in a sling. He now presents with persistent pain and motion at the fracture site. Radiographs confirm a non-union. Which of the following initial injury characteristics was the most significant risk factor for this outcome?

. Initial displacement greater than 100% (off-ended)
. Fracture location in the distal third
. Age less than 40 years
. Associated undisplaced rib fractures
. Treatment with a simple sling rather than a figure-of-eight brace

Correct Answer & Explanation

. Initial displacement greater than 100% (off-ended)

Explanation

The most significant risk factors for non-union in midshaft clavicle fractures are 100% displacement (lack of cortical contact), shortening greater than 2 cm, and severe comminution.

Question 1373

Topic: Upper Extremity Trauma
A 24-year-old rugby player falls directly onto his shoulder and sustains an acute acromioclavicular (AC) joint separation. Radiographs reveal 150% superior displacement of the distal clavicle relative to the acromion. Which ligaments are completely disrupted in this Type III injury?
. Acromioclavicular ligaments only
. Coracoclavicular ligaments only
. Acromioclavicular and coracoclavicular ligaments
. Coracoacromial ligaments only
. Sternoclavicular and acromioclavicular ligaments

Correct Answer & Explanation

. Acromioclavicular and coracoclavicular ligaments

Explanation

In a Type III AC joint separation, both the acromioclavicular (AC) ligaments and the coracoclavicular (CC) ligaments (conoid and trapezoid) are completely torn, allowing the clavicle to displace superiorly by 100-250%.

Question 1374

Topic: Upper Extremity Trauma

According to recent quantitative anatomic studies regarding the proximal humerus, which vessel provides the predominant blood supply to the humeral head, challenging historical teachings?

. Arcuate branch of the anterior humeral circumflex artery
. Posterior humeral circumflex artery
. Thoracoacromial artery
. Suprascapular artery
. Circumflex scapular artery

Correct Answer & Explanation

. Posterior humeral circumflex artery

Explanation

While historically the arcuate branch of the anterior humeral circumflex artery was believed to be the main supply, modern studies (e.g., Hettrich et al.) demonstrate that the posterior humeral circumflex artery provides over 60% of the blood supply to the humeral head.

Question 1375

Topic: 2. Trauma

A 45-year-old man presents to the emergency department complaining of severe right shoulder pain and an inability to rotate his arm outward following a generalized tonic-clonic seizure. Based on typical radiographic findings for this mechanism of injury, what is the most likely diagnosis?

. Anterior shoulder dislocation
. Posterior shoulder dislocation
. Inferior shoulder dislocation (luxatio erecta)
. Acromioclavicular joint separation
. Proximal humerus surgical neck fracture

Correct Answer & Explanation

. Posterior shoulder dislocation

Explanation

Seizures and electrical shocks classically cause posterior shoulder dislocations because the strong internal rotators overpower the external rotators. The arm is characteristically locked in internal rotation, and AP radiographs typically show the 'lightbulb sign'.

Question 1376

Topic: 2. Trauma

A 25-year-old male sustains a comminuted midshaft tibia fracture. Four hours post-admission, he develops severe calf pain out of proportion to the injury, exacerbated by passive toe extension. Which measured parameter is the most reliable threshold for indicating emergent fasciotomy?

. Absolute compartment pressure > 20 mmHg
. Diastolic blood pressure minus compartment pressure < 30 mmHg
. Mean arterial pressure minus compartment pressure < 30 mmHg
. Systolic blood pressure minus compartment pressure < 40 mmHg
. Absolute compartment pressure > 25 mmHg

Correct Answer & Explanation

. Diastolic blood pressure minus compartment pressure < 30 mmHg

Explanation

The Delta P (diastolic blood pressure minus intracompartmental pressure) is the most reliable indicator for acute compartment syndrome. A Delta P of less than 30 mmHg represents inadequate tissue perfusion and is an absolute indication for fasciotomy.

Question 1377

Topic: 2. Trauma

A 35-year-old female falls on an outstretched hand and sustains a closed, displaced fracture of the distal third of the radial shaft along with a dislocation of the distal radioulnar joint (DRUJ). What is the eponymous classification for this specific injury pattern?

. Monteggia fracture
. Galeazzi fracture
. Colles fracture
. Smith fracture
. Barton fracture

Correct Answer & Explanation

. Galeazzi fracture

Explanation

A Galeazzi fracture is defined as a fracture of the distal third of the radius with an associated dislocation or subluxation of the distal radioulnar joint (DRUJ). It invariably requires open reduction and internal fixation in adults.

Question 1378

Topic: 2. Trauma

A 32-year-old female falls onto her outstretched arm, sustaining a complex elbow injury. The orthopedic surgeon describes the injury as the 'terrible triad' of the elbow. Which of the following distinct injury components define this triad?

. Coronoid fracture, radial head fracture, and elbow dislocation
. Olecranon fracture, radial head fracture, and elbow dislocation
. Medial epicondyle fracture, lateral epicondyle fracture, and elbow dislocation
. Coronoid fracture, capitellum fracture, and radial head fracture
. Radial head fracture, ulnar shaft fracture, and DRUJ dislocation

Correct Answer & Explanation

. Coronoid fracture, radial head fracture, and elbow dislocation

Explanation

The 'terrible triad' of the elbow consists of a posterior elbow dislocation, a radial head fracture, and a coronoid fracture. It is notoriously difficult to manage due to severe resulting rotatory and varus/valgus instability.

Question 1379

Topic: 2. Trauma

A 40-year-old male is evaluated in the emergency department for severe shoulder pain and a locked internal rotation deformity following an electrocution injury. An AP radiograph demonstrates the "lightbulb sign." Which of the following associated lesions is most likely present?

. Anterior inferior capsular avulsion
. Impaction fracture of the anteromedial humeral head
. Impaction fracture of the posterolateral humeral head
. Superior labrum anterior to posterior (SLAP) tear
. Avulsion fracture of the greater tuberosity

Correct Answer & Explanation

. Impaction fracture of the anteromedial humeral head

Explanation

The patient's presentation and the "lightbulb sign" indicate a posterior shoulder dislocation. This injury is frequently associated with a reverse Hill-Sachs lesion, which is an impaction fracture of the anteromedial aspect of the humeral head.

Question 1380

Topic: Upper Extremity Trauma

A 28-year-old collegiate baseball pitcher presents with deep shoulder pain, mechanical clicking, and decreased throwing velocity. The pain is strongly reproduced with resisted forearm supination while the shoulder is flexed to 90 degrees. Which structure is most likely injured?

. Subscapularis tendon
. Long head of the biceps anchor
. Acromioclavicular joint
. Pectoralis major tendon
. Coracoacromial ligament

Correct Answer & Explanation

. Long head of the biceps anchor

Explanation

The patient's presentation and positive O'Brien's or Yergason's test are consistent with a SLAP (Superior Labrum Anterior and Posterior) tear. These lesions involve the superior labrum and the origin of the long head of the biceps tendon.

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