Menu

2. Trauma MCQs

Practice Set 561 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 11201

Topic: Upper Extremity Trauma

In the biomechanics of the acromioclavicular (AC) joint, the coracoclavicular (CC) ligaments provide primary vertical and axial stability. Which of the following statements accurately describes the specific anatomy and function of the CC ligaments?

. The conoid ligament is lateral to the trapezoid and resists anterior translation.
. The trapezoid ligament is medial to the conoid and resists superior translation.
. The conoid ligament is medial to the trapezoid and is the primary restraint to superior displacement of the clavicle.
. The trapezoid ligament is the primary restraint to inferior displacement of the clavicle.
. Both ligaments blend together identically to primarily resist anterior-posterior translation of the clavicle.

Correct Answer & Explanation

. The conoid ligament is lateral to the trapezoid and resists anterior translation.

Explanation

The coracoclavicular complex consists of the conoid and trapezoid ligaments. The conoid ligament is located posteromedially and is the primary restraint to superior translation of the clavicle. The trapezoid ligament is located anterolaterally and primarily restricts axial compression (acromion translating medially beneath the clavicle).

Question 11202

Topic: Upper Extremity Trauma

A 42-year-old male sustains a complete distal triceps tendon rupture after a fall on an outstretched hand. During surgical repair using a transosseous cruciate technique, it is crucial to reattach the tendon to its anatomic footprint. Where is the normal anatomic insertion footprint of the triceps tendon?

. Centered exclusively on the absolute tip of the olecranon
. Broadly across the olecranon dome, attaching slightly distal to the articular margin
. Medial to the sublime tubercle of the ulna
. Directly onto the coronoid process
. Along the lateral border of the proximal radius

Correct Answer & Explanation

. Centered exclusively on the absolute tip of the olecranon

Explanation

The triceps tendon inserts over a broad, dome-shaped footprint on the proximal olecranon. It begins slightly distal (1-2 cm) to the articular margin of the olecranon tip and extends distally. The deep medial head fibers insert closer to the joint line, while the lateral and long heads insert more superficially and distally.

Question 11203

Topic: 2. Trauma

A 34-year-old female sustains a coronal shear fracture of the distal humerus involving the capitellum and the lateral aspect of the trochlea. The fracture extends into the lateral epicondyle. Which surgical approach provides the most optimal visualization for open reduction and internal fixation?

. Posterior approach with olecranon osteotomy
. Anterior approach of Henry
. Extended lateral (extensile lateral) approach
. Medial approach
. Posterior approach with triceps split

Correct Answer & Explanation

. Posterior approach with olecranon osteotomy

Explanation

The extended lateral approach provides excellent exposure for coronal shear fractures involving the capitellum and lateral trochlea, allowing anterior-to-posterior or posterior-to-anterior screw fixation.

Question 11204

Topic: 2. Trauma

A 65-year-old female sustains a complex proximal humerus fracture. According to the Hertel criteria, which of the following radiographic features is the most reliable predictor of humeral head ischemia?

. Displaced greater tuberosity fracture
. Metaphyseal head extension greater than 8 mm
. Medial calcar hinge length less than 2 mm
. Varus angulation greater than 20 degrees
. Displacement of the surgical neck greater than 1 cm

Correct Answer & Explanation

. Displaced greater tuberosity fracture

Explanation

Hertel's criteria identify a medial hinge length of less than 2 mm, an intact posteromedial metaphyseal extension of less than 8 mm, and anatomic neck fracture patterns as the most significant predictors of ischemia.

Question 11205

Topic: Upper Extremity Trauma

A 25-year-old cyclist falls directly onto his shoulder, sustaining a Type V acromioclavicular (AC) joint separation. The surgeon plans a coracoclavicular (CC) ligament reconstruction. Which of the following accurately describes the anatomic insertions of the native CC ligaments on the clavicle?

. Conoid inserts posteromedial, Trapezoid anterolateral
. Conoid inserts anterolateral, Trapezoid posteromedial
. Conoid inserts directly anterior, Trapezoid directly posterior
. Both insert conjointly on the lateral border of the acromion
. Conoid inserts on the coracoid process, Trapezoid on the sternum

Correct Answer & Explanation

. Conoid inserts posteromedial, Trapezoid anterolateral

Explanation

The conoid ligament inserts posteromedially on the conoid tubercle (roughly 45 mm from the distal clavicle), while the trapezoid ligament inserts anterolaterally (roughly 25 mm from the distal clavicle).

Question 11206

Topic: Lower Extremity Trauma
When comparing two solid cylindrical titanium rods used for intramedullary nailing, Rod A has a radius of 'r' and Rod B has a radius of '2r'. By what factor does the area moment of inertia (and therefore the bending stiffness) increase in Rod B compared to Rod A?
. 2
. 4
. 8
. 16
. 32

Correct Answer & Explanation

. 16

Explanation

The area moment of inertia (I) for a solid cylinder is calculated as I = (π × r^4) / 4. Therefore, bending stiffness is proportional to the radius to the fourth power (r^4). If the radius is doubled (2r), the bending stiffness increases by a factor of 2^4, which equals 16.

Question 11207

Topic: 2. Trauma

Which of the following fracture fixation constructs relies entirely on secondary bone healing (endochondral ossification with callus formation)?

. Absolute stability via a dynamic compression plate
. Interfragmentary compression via a lag screw alone
. Relative stability via an intramedullary nail
. Anatomic reduction with tension band wiring of a patella
. Rigid double-plating of a distal humerus fracture

Correct Answer & Explanation

. Absolute stability via a dynamic compression plate

Explanation

Primary bone healing occurs without callus formation and requires absolute stability (e.g., lag screws, compression plates) where strain is less than 2%. Secondary bone healing involves callus formation (endochondral and intramembranous ossification) and occurs in environments of relative stability (strain between 2% and 10%). Intramedullary nails act as load-sharing devices that provide relative stability, promoting robust secondary healing.

Question 11208

Topic: 2. Trauma
Which recombinant human bone morphogenetic protein (rhBMP) is FDA-approved (as an osteoinductive agent on an absorbable collagen sponge) for use in acute, open tibial shaft fractures treated with an intramedullary nail?
. rhBMP-2
. rhBMP-3
. rhBMP-4
. rhBMP-7
. rhBMP-9

Correct Answer & Explanation

. rhBMP-2

Explanation

rhBMP-2 (INFUSE) is FDA-approved for acute open tibial shaft fractures, as well as single-level ALIF procedures. rhBMP-7 (OP-1) was historically approved under a Humanitarian Device Exemption (HDE) for recalcitrant tibial nonunions.

Question 11209

Topic: 2. Trauma

When reaming the femoral medullary canal for an intramedullary nail, a surgeon decides to substitute a 10 mm diameter solid nail with a 12 mm diameter solid nail. By approximately what factor does the torsional rigidity of the implant increase?

. 1.2
. 1.44
. 1.7
. 2.07
. 4.0

Correct Answer & Explanation

. 1.2

Explanation

The torsional rigidity of a solid cylinder is directly proportional to its polar moment of inertia, which scales with the radius to the fourth power (r^4). Therefore, increasing the diameter from 10 mm to 12 mm increases the torsional rigidity by a factor of (12/10)^4 = 1.2^4 = 2.07.

Question 11210

Topic: 2. Trauma

When using a bridge plate construct for a comminuted diaphyseal fracture, increasing the working length of the plate (the distance between the innermost screws) has what biomechanical effect on the construct?

. Decreases axial stiffness and increases torsional stiffness
. Increases axial stiffness and decreases torsional stiffness
. Decreases both axial and torsional stiffness
. Increases both axial and torsional stiffness
. Has no effect on stiffness

Correct Answer & Explanation

. Decreases axial stiffness and increases torsional stiffness

Explanation

Increasing the working length of a plate increases the overall flexibility of the construct by decreasing both axial and torsional stiffness. This controlled flexibility allows for micromotion, which promotes secondary bone healing through callus formation.

Question 11211

Topic: Lower Extremity Trauma

An orthopedic surgeon reams the medullary canal to accommodate a larger diameter intramedullary nail for a tibial shaft fracture. Increasing the radius of a solid cylindrical intramedullary nail increases its torsional rigidity by a factor proportional to which power of the radius?

. r^2
. r^3
. r^4
. r^5
. r^6

Correct Answer & Explanation

. r^2

Explanation

The torsional rigidity of a solid cylindrical implant is proportional to the polar moment of inertia, which varies with the radius to the fourth power (r^4). Therefore, small increases in nail diameter drastically increase resistance to torsional forces.

Question 11212

Topic: 2. Trauma
A patient suffers a closed humerus shaft fracture with immediate complete radial nerve palsy. According to the Sunderland classification, a Grade III nerve injury is best defined by disruption of which structures?
. Myelin sheath only (axon intact)
. Axon only (endoneurium intact)
. Axon and endoneurium (perineurium intact)
. Axon, endoneurium, and perineurium (epineurium intact)
. Complete nerve transection

Correct Answer & Explanation

. Axon and endoneurium (perineurium intact)

Explanation

Sunderland Grade III injuries involve loss of axon continuity and endoneurial tubes, while the perineurium and epineurium remain intact. This disruption can lead to internal scarring and unpredictable, often incomplete, recovery compared to Grade II injuries.

Question 11213

Topic: 2. Trauma

When applying a bridging locked plate for a comminuted diaphyseal femur fracture, how does increasing the 'working length' of the plate affect the biomechanics of the construct?

. It increases the torsional stiffness of the construct
. It decreases the bending stiffness of the construct
. It forces the fracture to heal via primary osteonal remodeling
. It decreases interfragmentary motion across the fracture gap
. It exponentially increases the pull-out strength of the screws

Correct Answer & Explanation

. It increases the torsional stiffness of the construct

Explanation

The 'working length' of a plate is defined as the distance between the innermost screws on either side of the fracture. Increasing the working length decreases the overall stiffness (both bending and torsional) of the construct. This decrease in stiffness allows for controlled interfragmentary micromotion, which stimulates secondary bone healing via cartilaginous soft callus formation.

Question 11214

Topic: 2. Trauma
The pull-out strength of a standard cortical screw used in fracture fixation is directly proportional to all of the following parameters EXCEPT:
. Outer diameter of the screw threads
. Length of thread engagement in the bone
. Inner (root) diameter of the screw
. Shear strength of the surrounding cortical bone

Correct Answer & Explanation

. Inner (root) diameter of the screw

Explanation

The pull-out strength of a screw is proportional to the shear area of the bone threads. The formula is approximately Force = (Outer Diameter) x (Length of Engagement) x (Bone Shear Strength) x (pi) x (Thread Shape Factor). The inner (root) diameter of the screw dictates the tensile and torsional strength of the screw itself (i.e., its resistance to breaking), but NOT its pull-out strength from the bone.

Question 11215

Topic: 2. Trauma

Which of the following biomechanical environments is strictly required to achieve primary bone healing (direct cortical remodeling) of a fracture?

. Presence of micromotion up to 2 mm
. Extensive fracture hematoma preservation
. Absolute stability with a gap less than 0.1 mm
. A relatively high strain environment
. Endochondral ossification potential

Correct Answer & Explanation

. Presence of micromotion up to 2 mm

Explanation

Primary bone healing occurs without callus formation and requires absolute mechanical stability (rigid fixation) with a fracture gap of less than 0.1 mm (contact healing). It relies entirely on osteonal remodeling by cutting cones across the fracture site.

Question 11216

Topic: 2. Trauma

In the management of a polytraumatized patient, which of the following physiological parameters is the most reliable indicator that the patient is adequately resuscitated and safe to proceed with Early Total Care (ETC) rather than Damage Control Orthopedics (DCO)?

. Lactate < 2.5 mmol/L
. Base deficit > 6 mEq/L
. Platelet count < 90,000/mcL
. Core body temperature 33°C
. Fibrinogen < 1 g/L

Correct Answer & Explanation

. Lactate < 2.5 mmol/L

Explanation

A serum lactate level < 2.5 mmol/L is a reliable indicator of adequate tissue perfusion and resuscitation, permitting definitive fracture fixation (ETC). A base deficit > 6, hypothermia, coagulopathy, and thrombocytopenia are signs of a patient 'in extremis' or borderline, which favors a Damage Control Orthopedics (DCO) approach.

Question 11217

Topic: 2. Trauma

A macrosomic newborn presents with pseudoparalysis of the right upper extremity following a difficult, prolonged vaginal delivery complicated by shoulder dystocia. On examination, the Moro reflex is absent on the right, but the grasp reflex is intact. Radiographs demonstrate no skeletal fractures. What is the most likely diagnosis?

. Klumpke palsy
. Erb-Duchenne palsy
. Neonatal proximal humerus physeal separation
. Neonatal clavicle fracture
. Cerebral palsy

Correct Answer & Explanation

. Erb-Duchenne palsy

Explanation

Erb's palsy involves the upper trunk of the brachial plexus (C5-C6). Clinically, it presents with the arm internally rotated and adducted (waiter's tip posture). The Moro reflex is absent due to the inability to abduct and externally rotate the shoulder, but the grasp reflex (C8-T1) remains intact. Klumpke palsy would present with an absent grasp reflex.

Question 11218

Topic: Pelvic & Acetabular Trauma

A hemodynamically unstable 40-year-old male is brought to the trauma bay after a high-speed motorcycle accident. An AP pelvis radiograph reveals an 'open book' anterior-posterior compression (APC) pelvic ring injury. Where is the correct anatomical level to place a non-invasive circumferential pelvic binder?

. Over the iliac crests
. Over the anterior superior iliac spines
. Over the greater trochanters
. Over the symphysis pubis
. Over the lower lumbar spine

Correct Answer & Explanation

. Over the greater trochanters

Explanation

To effectively reduce pelvic volume and control venous bleeding in an unstable pelvic ring injury, the pelvic binder or sheet must be centered directly over the greater trochanters. Placing it over the iliac crests is a common error and can paradoxical widen the pelvic outlet or fail to close the ring adequately.

Question 11219

Topic: 2. Trauma
A 30-year-old male sustains a Gustilo-Anderson Type IIIA open tibial shaft fracture after being struck by a car. Which of the following interventions has been proven to be the most critical independent factor in reducing the patient's risk of deep infection?
. Time to surgical debridement < 6 hours
. Application of negative pressure wound therapy
. Early administration of systemic intravenous antibiotics
. High-pressure pulsatile lavage during debridement
. Immediate primary closure of the traumatic wound

Correct Answer & Explanation

. Early administration of systemic intravenous antibiotics

Explanation

The early administration of systemic antibiotics (ideally within 1-3 hours of injury) is universally recognized as the single most important factor in reducing infection rates in open fractures. The '6-hour rule' for surgical debridement has not been strongly supported by modern evidence as an independent predictor of infection, provided antibiotics are given early.

Question 11220

Topic: 2. Trauma
A 25-year-old male sustains a Pauwels type III (highly vertical) intracapsular femoral neck fracture. Which of the following fixation constructs offers the highest biomechanical stability against shear forces for this specific fracture pattern?
. Three parallel partially threaded cancellous screws placed in an inverted triangle
. A fixed-angle sliding hip screw (SHS) combined with an anti-rotation screw
. Three fully threaded cancellous screws
. A short cephalomedullary nail
. Bipolar hemiarthroplasty

Correct Answer & Explanation

. A fixed-angle sliding hip screw (SHS) combined with an anti-rotation screw

Explanation

Biomechanical studies consistently show that for vertical shear fracture patterns (Pauwels III), a sliding hip screw combined with a derotation screw provides superior fixation strength and resistance to shear forces compared to multiple parallel cancellous screws.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page