Menu

2. Trauma MCQs

Practice Set 355 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 7081

Topic: 2. Trauma

A 32-year-old woman falls on an outstretched arm. Radiographs (

) demonstrate a coronal shear fracture of the capitellum extending into the lateral trochlea (Type IV). Which surgical approach and fixation strategy is biomechanically superior?

. Medial approach with tension band wiring
. Lateral approach with headless compression screws placed anterior-to-posterior
. Posterior approach with olecranon osteotomy
. Lateral approach with headless compression screws placed posterior-to-anterior
. Arthroscopic excision of the fracture fragment

Correct Answer & Explanation

. Lateral approach with headless compression screws placed posterior-to-anterior

Explanation

Coronal shear fractures of the capitellum are best managed with headless compression screws. A posterior-to-anterior screw trajectory provides superior biomechanical pull-out strength and avoids violating the anterior articular cartilage.

Question 7082

Topic: 2. Trauma

A 28-year-old man sustains a closed distal-third spiral fracture of the humeral shaft. On initial presentation, his neurologic examination is completely intact. Closed reduction and splinting are performed. Post-reduction, he is entirely unable to extend his wrist or fingers. What is the most appropriate next step in management?

. Immediate surgical exploration and nerve release
. Observation and serial examinations for 3 months
. Immediate Electromyography (EMG)
. Application of a hanging arm cast
. Ultrasound of the nerve

Correct Answer & Explanation

. Immediate surgical exploration and nerve release

Explanation

A secondary radial nerve palsy that develops immediately after a closed reduction attempt of a humeral shaft fracture (especially a Holstein-Lewis type) is an absolute indication for immediate surgical exploration. The nerve may be entrapped in the fracture site.

Question 7083

Topic: Upper Extremity Trauma

A 31-year-old competitive weightlifter feels a tearing sensation in his anterior chest while performing a heavy bench press. Examination reveals loss of the anterior axillary fold and weakness in internal rotation. The most common site of this specific muscle injury is:

. Muscle belly of the sternal head
. Avulsion of the tendon from the humerus
. Myotendinous junction
. Avulsion from the clavicle
. Sternocostal origin

Correct Answer & Explanation

. Avulsion of the tendon from the humerus

Explanation

Pectoralis major ruptures most commonly occur as an avulsion of the tendon from its insertion on the proximal humerus. They are classic injuries in weightlifters performing bench presses, often requiring surgical repair for optimal return to strength.

Question 7084

Topic: 2. Trauma

A 22-year-old man falls onto an extended wrist. Radiographs reveal a non-displaced fracture of the proximal pole of the scaphoid. Why is this specific fracture location at a particularly high risk for nonunion and avascular necrosis?

. The proximal pole has multiple robust capsular attachments that distract the fragment
. The blood supply enters distally and flows retrograde to the proximal pole
. The fracture is subjected to high distraction forces from the flexor carpi radialis
. The proximal pole completely lacks hyaline cartilage coverage
. High impact of the radiocarpal ligaments tears local perforators

Correct Answer & Explanation

. The blood supply enters distally and flows retrograde to the proximal pole

Explanation

The scaphoid receives its primary blood supply from the dorsal carpal branch of the radial artery, which enters the distal half and flows retrograde. Fractures of the proximal pole frequently disrupt this delicate blood supply, causing avascular necrosis.

Question 7085

Topic: 2. Trauma
A 6-year-old boy falls off monkey bars. Radiographs demonstrate a fracture of the proximal third of the ulna with an anterior dislocation of the radial head. According to the Bado classification, this injury is classified as a:
. 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 fracture-dislocation is characterized by a fracture of the proximal or middle third of the ulna with an anterior dislocation of the radial head. It is the most common variant seen in pediatric patients.

Question 7086

Topic: 2. Trauma

A 40-year-old woman falls on her outstretched arm and sustains an isolated coronal shear fracture of the humeral capitellum. What is the optimal surgical approach and fixation strategy for this injury?

. Posterior approach with olecranon osteotomy and crossed K-wires
. Lateral approach with anterior-to-posterior headless compression screws
. Medial approach with a buttress plate
. Anterior approach with heavy suture repair of the capsule
. Closed reduction and percutaneous pinning

Correct Answer & Explanation

. Lateral approach with anterior-to-posterior headless compression screws

Explanation

Capitellum fractures are coronal shear injuries of the distal humerus. They are best managed through a lateral approach using headless compression screws placed from anterior to posterior, allowing the hardware to be buried beneath the articular cartilage.

Question 7087

Topic: 2. Trauma

A 72-year-old female presents with a highly comminuted, intra-articular distal humerus fracture (OTA 13-C3) after a ground-level fall. Her bone quality is poor, and the articular surface is deemed non-reconstructible. She lives independently and performs her own activities of daily living. What is the most appropriate definitive management?

. Open reduction and internal fixation with dual plates
. Total elbow arthroplasty
. Non-operative management with early mobilization
. Hemiarthroplasty
. Spanning external fixation

Correct Answer & Explanation

. Total elbow arthroplasty

Explanation

In elderly patients with complex, non-reconstructible intra-articular distal humerus fractures, total elbow arthroplasty provides superior functional outcomes and lower reoperation rates compared to open reduction and internal fixation.

Question 7088

Topic: 2. Trauma

A 24-year-old professional baseball player sustains a fall onto an outstretched hand. Initial radiographs are negative, but an MRI reveals an acute, non-displaced fracture of the scaphoid waist. He wishes to return to play as safely and quickly as possible. What is the optimal management?

. Long arm thumb spica cast for 6 weeks
. Scaphoid excision and four-corner fusion
. Percutaneous screw fixation
. ORIF with vascularized pedicled bone graft
. Proximal row carpectomy

Correct Answer & Explanation

. Percutaneous screw fixation

Explanation

Percutaneous screw fixation of acute, non-displaced scaphoid waist fractures results in faster time to union and significantly quicker return to sport and work compared to prolonged cast immobilization.

Question 7089

Topic: 2. Trauma

To decrease the stiffness of a locking plate construct and promote secondary bone healing via callus formation in a comminuted diaphyseal fracture, which technique should the surgeon employ?

. Place screws in every hole of the plate
. Use a thicker plate
. Decrease the working length of the plate
. Increase the working length by leaving holes empty over the fracture site
. Use a plate made of a stiffer material like cobalt-chromium

Correct Answer & Explanation

. Increase the working length by leaving holes empty over the fracture site

Explanation

Increasing the working length of the plate (the distance between the innermost screws on either side of the fracture) decreases the overall construct stiffness, allowing interfragmentary motion that stimulates secondary bone healing.

Question 7090

Topic: 2. Trauma

A comminuted tibial shaft fracture is treated with biological fixation using a submuscular bridge plate. Healing is expected to occur via robust callus formation. According to Perren's strain theory, what is the optimal interfragmentary strain environment for this type of secondary bone healing?

. Less than 2%
. 2% to 10%
. 10% to 30%
. 30% to 50%
. Greater than 50%

Correct Answer & Explanation

. Less than 2%

Explanation

Secondary bone healing characterized by cartilaginous callus formation occurs optimally at an interfragmentary strain of 2% to 10%. Strains less than 2% favor primary (osteonal) bone healing, whereas strains above 10% favor fibrous tissue formation or nonunion.

Question 7091

Topic: Lower Extremity Trauma

In orthopedic biomechanics, for a solid cylindrical intramedullary nail, the bending stiffness is proportional to the radius raised to which power?

. Second power
. Third power
. Fourth power
. Fifth power
. Inverse of the radius

Correct Answer & Explanation

. Second power

Explanation

The bending stiffness of a solid cylinder is directly proportional to its area moment of inertia. For a solid cylinder, the area moment of inertia is proportional to the radius to the fourth power (r^4).

Question 7092

Topic: 2. Trauma

During internal fixation of a diaphyseal fracture, which design modification of a cortical bone screw will most effectively increase its pullout strength?

. Decreasing the outer (major) diameter
. Increasing the inner (minor) diameter
. Increasing the thread pitch
. Increasing the outer (major) diameter
. Decreasing the length of thread engagement

Correct Answer & Explanation

. Decreasing the outer (major) diameter

Explanation

Screw pullout strength is most significantly increased by increasing the outer (major) diameter. This dictates the volume of bone captured between the screw threads and is the single most important factor for pullout resistance.

Question 7093

Topic: 2. Trauma

Aggrecan, the primary proteoglycan found in articular cartilage, is responsible for providing which essential biomechanical property to the tissue?

. Tensile strength
. Shear resistance
. Compressive stiffness
. Elastic recoil
. Fracture toughness

Correct Answer & Explanation

. Tensile strength

Explanation

Aggrecan is highly negatively charged due to its glycosaminoglycan chains, which attract water via the Donnan osmotic effect. This swelling pressure, constrained by the type II collagen network, provides cartilage with its compressive stiffness.

Question 7094

Topic: 2. Trauma

The pull-out strength of a cortical screw used in fracture fixation is heavily dependent on screw design and bone quality. Based on screw geometry, pull-out strength is directly proportional to which of the following dimensions?

. Inner (core) diameter
. Outer (thread) diameter
. Screw pitch
. Screw head diameter
. Drive mechanism size

Correct Answer & Explanation

. Inner (core) diameter

Explanation

Screw pull-out strength is directly proportional to the outer (thread) diameter, the length of thread engagement, and the shear strength of the surrounding bone. Inner core diameter primarily determines the screw's tensile and torsional strength.

Question 7095

Topic: Lower Extremity Trauma

An orthopedic surgeon decides to change an intramedullary nail from a solid titanium rod with a radius of 'r' to a solid titanium rod with a radius of '2r'. Assuming identical material properties, by what factor does the bending rigidity of the nail increase?

. 2
. 4
. 8
. 16
. 32

Correct Answer & Explanation

. 2

Explanation

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

Question 7096

Topic: 2. Trauma

When applying a conventional non-locking plate to a diaphyseal fracture, over-tightening the screws compresses the plate directly to the bone. This construct relies on which fundamental biomechanical principle for stability?

. Splinting
. Friction between the plate and the bone
. Interfragmentary compression
. Tension band effect
. Fixed-angle load sharing

Correct Answer & Explanation

. Splinting

Explanation

Conventional non-locking plates rely entirely on friction generated between the underside of the plate and the bone surface to resist functional loads. Locking plates, in contrast, rely on fixed-angle screw-plate interfaces and do not require bone contact for stability.

Question 7097

Topic: 2. Trauma

A 45-year-old man undergoes fixation of a comminuted femoral shaft fracture with a bridging locked plate. To decrease the construct stiffness and promote secondary bone healing via callus formation, which of the following technical modifications is most appropriate?

. Using a shorter plate overall
. Filling all plate holes with bicortical screws
. Increasing the distance between the innermost screws by leaving empty holes over the fracture
. Using unicortical screws at the plate ends
. Placing the plate further from the bone surface

Correct Answer & Explanation

. Using a shorter plate overall

Explanation

Leaving empty holes over the fracture increases the working length of the plate. This decreases construct stiffness and promotes interfragmentary motion, which is necessary for secondary bone healing.

Question 7098

Topic: 2. Trauma

Which of the following biomechanical conditions is strictly required to achieve primary (direct) bone healing without intermediate callus formation?

. Absolute stability and interfragmentary compression
. Relative stability and a strain environment of 2-10%
. Bridging plate fixation with a long working length
. Intramedullary nailing with dynamic locking
. External fixation with dynamization

Correct Answer & Explanation

. Absolute stability and interfragmentary compression

Explanation

Primary bone healing (contact healing via cutting cones) requires absolute stability and anatomic reduction with strain less than 2%. All other options describe relative stability, which leads to secondary healing with callus.

Question 7099

Topic: 2. Trauma

Recombinant human bone morphogenetic protein-2 (rhBMP-2) is currently FDA-approved for use in which of the following orthopedic scenarios?

. Closed femoral shaft fractures
. Acute open tibial shaft fractures treated with an intramedullary nail
. Nonunion of the scaphoid
. Posterolateral lumbar fusion
. Distal radius fractures treated with a volar plate

Correct Answer & Explanation

. Closed femoral shaft fractures

Explanation

rhBMP-2 is FDA-approved for acute open tibial shaft fractures treated with an intramedullary nail and for anterior lumbar interbody fusion (ALIF). It is not approved for posterolateral lumbar fusion or routine upper extremity fractures.

Question 7100

Topic: Lower Extremity Trauma

A surgeon chooses to ream the femoral canal to upsize a solid intramedullary nail from 10 mm to 12 mm in diameter. By what approximate factor does the bending stiffness of the solid nail increase?

. 1.20
. 1.44
. 1.73
. 2.07
. 2.44

Correct Answer & Explanation

. 1.20

Explanation

The bending stiffness of a solid cylinder is proportional to the area moment of inertia, which scales with the radius to the fourth power (r^4). Therefore, increasing diameter by a factor of 1.2 yields a stiffness increase of (1.2)^4, or roughly 2.07.

Test Yourself

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

On this Page