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2. Trauma MCQs

Practice Set 225 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 4481

Topic: 2. Trauma

A 19-year-old collegiate basketball player sustains a Zone 2 fracture of the proximal fifth metatarsal (Jones fracture). Why do these specific fractures have a disproportionately high rate of delayed union and nonunion?

. The zone has a rich retrograde blood supply from the distal metatarsal.
. It represents a vascular watershed area between the metaphyseal and nutrient arteries.
. The nutrient artery enters the base of the metatarsal directly at this zone.
. Avascular necrosis of the metatarsal head is the most common complication.
. The fracture disrupts the lateral tarsal artery.

Correct Answer & Explanation

. The zone has a rich retrograde blood supply from the distal metatarsal.

Explanation

Zone 2 fractures (Jones fractures) occur at the metaphyseal-diaphyseal junction, which is a vascular watershed area between the proximal metaphyseal vessels and the distal nutrient artery. This tenuous blood supply contributes directly to high rates of nonunion.

Question 4482

Topic: 2. Trauma

A 25-year-old professional basketball player sustains an acute fracture at the metaphyseal-diaphyseal junction of the fifth metatarsal. To facilitate the fastest and safest return to elite-level play, what is the recommended treatment?

. Short leg cast non-weight-bearing for 6 weeks
. Hard-soled shoe weight-bearing as tolerated
. Intramedullary screw fixation
. Plating of the lateral fifth metatarsal
. Excision of the proximal fragment and peroneus brevis advancement

Correct Answer & Explanation

. Intramedullary screw fixation

Explanation

Acute Zone 2 (Jones) fractures in elite athletes are treated with early intramedullary screw fixation. This provides robust biomechanical stability, decreases the risk of nonunion, and allows for an accelerated return to sport.

Question 4483

Topic: 2. Trauma

A 35-year-old man sustains a closed spiral fracture of the distal third of the humeral shaft (Holstein-Lewis type). On examination in the emergency department, he is unable to extend his wrist or fingers, but triceps function is completely intact.

What is the most appropriate initial management of this nerve injury?

. Immediate surgical exploration of the radial nerve and ORIF of the fracture.
. Splinting of the fracture, resting splint for the wrist, and clinical observation for 3 to 4 months.
. Early nerve conduction studies within 48 hours to determine the extent of nerve injury.
. External fixation of the humerus and delayed primary nerve repair at 3 weeks.
. Immediate tendon transfers to restore wrist and finger extension.

Correct Answer & Explanation

. Splinting of the fracture, resting splint for the wrist, and clinical observation for 3 to 4 months.

Explanation

Most radial nerve palsies associated with closed humeral shaft fractures, including Holstein-Lewis types, represent neurapraxia and will resolve spontaneously. The standard of care is initial observation for 3 to 4 months with supportive splinting. Surgical exploration is indicated if there is an open fracture, if the paralysis occurs acutely after a closed reduction attempt, or if there is no clinical or EMG evidence of recovery at 3 to 4 months.

Question 4484

Topic: 2. Trauma
A 7-year-old girl falls on an outstretched hand and sustains a Bado Type I Monteggia fracture-dislocation. She is noted to have a nerve palsy on presentation. What is the expected clinical presentation of her neurological deficit?
. Complete loss of wrist extension and finger extension with profound sensory loss over the dorsal hand.
. Weakness of finger and thumb extension with preserved, albeit radially deviated, wrist extension and no sensory loss.
. Weakness of wrist flexion and loss of sensation over the volar aspect of the fifth digit.
. Loss of thumb opposition and sensory loss over the volar index finger.
. Clawing of the index and middle fingers with intrinsic muscle wasting.

Correct Answer & Explanation

. Weakness of finger and thumb extension with preserved, albeit radially deviated, wrist extension and no sensory loss.

Explanation

The posterior interosseous nerve (PIN) is classically injured in Monteggia fractures, particularly Bado Type I and III. The PIN is a purely motor branch of the radial nerve that innervates the extensor muscles of the digits and the extensor carpi ulnaris (ECU). Because the extensor carpi radialis longus (ECRL) is innervated by the radial nerve proper proximal to the PIN bifurcation, wrist extension is preserved but deviates radially due to the paralyzed ECU. There is no sensory loss.

Question 4485

Topic: 2. Trauma

A 45-year-old man falls from a roof, sustaining a Zone 3 sacral fracture according to the Denis classification.

Which of the following neurological deficits is most commonly associated with this specific fracture zone?

. Isolated foot drop due to L5 involvement.
. Weakness of knee extension due to femoral nerve traction.
. Bowel, bladder, and sexual dysfunction.
. Loss of sensation over the lateral thigh.
. Weakness of hip flexion.

Correct Answer & Explanation

. Bowel, bladder, and sexual dysfunction.

Explanation

The Denis classification of sacral fractures divides the sacrum into three zones. Zone 3 involves the central sacral canal. Fractures in this zone have the highest rate of neurological injury (up to 60%), specifically affecting the lower sacral roots (S2-S4), which leads to sphincter disturbances resulting in bowel, bladder, and sexual dysfunction.

Question 4486

Topic: Pelvic & Acetabular Trauma
A 25-year-old male sustains an anteroposterior compression (APC) type III pelvic ring injury. He undergoes anterior plating of the symphysis pubis and percutaneous posterior sacroiliac (SI) joint screw fixation. Postoperatively, he is noted to have a foot drop and weakness in great toe extension, but sensation to the plantar aspect of the foot is intact. Which of the following nerve roots is most likely injured due to its precise anatomical relationship to the sacral ala?
. L3
. L4
. L5
. S1
. S2

Correct Answer & Explanation

. L5

Explanation

The L5 nerve root courses directly over the anterior aspect of the sacral ala as it joins the lumbosacral trunk. It is highly susceptible to stretch injury during significant SI joint disruptions or iatrogenic injury during placement of iliosacral screws if they breach the anterior cortex of the sacral ala. Injury presents with weakness in ankle dorsiflexion and great toe extension (foot drop).

Question 4487

Topic: 2. Trauma

A 19-year-old cyclist sustains a closed, highly displaced midshaft clavicle fracture that is treated nonoperatively. Several weeks later, he presents with new-onset progressive paresthesias in his medial forearm and hand, alongside weakness of intrinsic hand muscles.

Which of the following is the most likely cause of his neurological symptoms?

. Traction injury to the upper trunk of the brachial plexus during the initial trauma.
. Compression of the medial cord or lower trunk by hypertrophic callus formation.
. Iatrogenic traction injury from prolonged use of a figure-of-eight brace.
. Stretch injury to the long thoracic nerve causing secondary scapular winging.
. Subclavian artery pseudoaneurysm compressing the lateral cord.

Correct Answer & Explanation

. Compression of the medial cord or lower trunk by hypertrophic callus formation.

Explanation

Late-onset brachial plexus palsy after a clavicle fracture is typically caused by compression of the neurovascular bundle by hypertrophic callus from a nonunion or malunion. Due to its inferior anatomical location, the medial cord or lower trunk is most frequently compressed, leading to neurological symptoms in an ulnar nerve distribution (medial forearm/hand paresthesias and intrinsic weakness).

Question 4488

Topic: 2. Trauma

A 30-year-old soccer player sustains a twisting injury to the knee. Radiographs reveal an isolated, slightly displaced fracture of the fibular head. He exhibits a complete inability to dorsiflex his foot and has numbness over the entire dorsum of the foot, involving both the superficial and deep peroneal nerve territories. What is the typical mechanism of injury for the nerve in this specific scenario?

. Traction and stretch injury to the common peroneal nerve as it winds around the fibular neck.
. Direct sharp laceration of the nerve by a sharp fibular head bone fragment.
. Acute compartment syndrome of the anterior leg.
. Entrapment of the nerve within the proximal tibiofibular joint.
. Ischemic neuropathy from associated disruption of the anterior tibial recurrent artery.

Correct Answer & Explanation

. Traction and stretch injury to the common peroneal nerve as it winds around the fibular neck.

Explanation

Common peroneal nerve palsy associated with proximal fibula fractures or multiligamentous knee injuries is almost exclusively a traction/stretch injury. The nerve is tethered as it wraps around the fibular neck and passes under the peroneus longus fascia, making it highly vulnerable to stretch from varus stress or internal rotation forces. Direct laceration is exceedingly rare.

Question 4489

Topic: 2. Trauma

A 22-year-old man undergoes intramedullary nailing of a midshaft femur fracture on a fracture table.

The procedure takes 4 hours due to significant difficulty achieving a closed reduction. Postoperatively, he complains of numbness in his perineal region and presents with erectile dysfunction. What is the most likely cause of this complication?

. Direct iatrogenic injury to the pudendal nerve during antegrade reaming.
. Prolonged compression of the pudendal nerve against the perineal post of the fracture table.
. An undiagnosed concomitant nondisplaced sacral fracture.
. Traction injury to the lumbosacral plexus from longitudinal pull.
. Subclinical compartment syndrome of the thigh compressing the obturator nerve.

Correct Answer & Explanation

. Prolonged compression of the pudendal nerve against the perineal post of the fracture table.

Explanation

Pudendal nerve palsy is a well-documented complication of using a fracture table, resulting from prolonged compression of the nerve against the perineal post. It manifests as perineal numbness and erectile dysfunction. Preventive measures include minimizing traction time, ensuring adequate padding, and occasionally releasing traction if a delay occurs during surgery.

Question 4490

Topic: 2. Trauma

A 35-year-old man is struck by a car and sustains a Schatzker VI tibial plateau fracture.

He undergoes temporary spanning external fixation. Twelve hours later, he develops intractable leg pain out of proportion to his injury, severe pain with passive toe flexion, and decreased sensation in the first web space. His dorsalis pedis pulse remains palpable. Which of the following is the most accurate statement regarding his condition?

. The presence of a palpable pulse definitively rules out acute compartment syndrome.
. The sensory deficit indicates an isolated primary contusion to the superficial peroneal nerve.
. The anterior compartment of the leg is experiencing elevated pressures, compromising the deep peroneal nerve.
. Immediate removal of the external fixator is the definitive treatment.
. An emergent angiogram is required before any surgical intervention can be considered.

Correct Answer & Explanation

. The anterior compartment of the leg is experiencing elevated pressures, compromising the deep peroneal nerve.

Explanation

The patient exhibits classic signs of acute compartment syndrome (ACS) of the anterior leg. The anterior compartment contains the tibialis anterior, EHL, and EDL muscles; passive toe flexion stretches these extensors, eliciting severe pain. The deep peroneal nerve runs within the anterior compartment and provides sensation to the first web space; its compromise is an early sign of ACS. A palpable pulse does not rule out ACS, as tissue perfusion ceases at pressures well below systolic arterial pressure.

Question 4491

Topic: 2. Trauma

In a Holstein-Lewis fracture (a spiral fracture of the distal third of the humerus), the radial nerve is particularly vulnerable to entrapment or laceration.

At what specific anatomical location does the nerve typically become entrapped by the fracture fragments?

. As it pierces the lateral intermuscular septum to transit from the posterior to the anterior compartment.
. Deep within the spiral groove of the posterior mid-diaphysis.
. As it passes between the superficial and deep heads of the supinator muscle.
. Anterior to the lateral epicondyle just before it bifurcates.
. Within the axilla, as it runs posterior to the brachial artery.

Correct Answer & Explanation

. As it pierces the lateral intermuscular septum to transit from the posterior to the anterior compartment.

Explanation

The radial nerve is relatively fixed and tethered as it pierces the lateral intermuscular septum to pass from the posterior compartment to the anterior compartment of the arm, approximately 10 cm proximal to the lateral epicondyle. In a Holstein-Lewis fracture, the distal fracture fragment typically displaces proximally, trapping or impaling the tethered radial nerve between the bone ends.

Question 4492

Topic: 2. Trauma

An 18-year-old male sustains a closed distal third spiral humeral shaft fracture.

On physical examination, he is unable to actively extend his wrist or digits. What is the most appropriate initial management of this nerve palsy?

. Immediate surgical exploration
. Electromyography (EMG)
. Closed reduction and coaptation splinting, observation of the nerve
. MRI of the arm
. Ultrasound of the radial nerve

Correct Answer & Explanation

. Closed reduction and coaptation splinting, observation of the nerve

Explanation

This patient has a Holstein-Lewis fracture (distal third spiral humerus fracture) with an associated radial nerve palsy. The vast majority of these injuries are neuropraxias. The standard of care for a closed humeral shaft fracture with an acute radial nerve palsy is conservative management with closed reduction, splinting, and observation. Surgical exploration is indicated if the palsy occurs after a closed reduction attempt (iatrogenic), if it is an open fracture, or if there is no recovery after 3-4 months.

Question 4493

Topic: 2. Trauma
A 40-year-old female sustains a comminuted Denis Zone III sacral fracture after a fall from a height. Based on the anatomic location of this fracture, which of the following neurologic deficits is most frequently encountered?
. Weakness of ankle dorsiflexion
. Loss of perianal sensation and sphincter tone
. Weakness of great toe extension
. Numbness over the medial calf
. Weakness of hip flexion

Correct Answer & Explanation

. Loss of perianal sensation and sphincter tone

Explanation

Denis classified sacral fractures into three zones: Zone I (alar), Zone II (foraminal), and Zone III (central canal). Zone III fractures frequently involve the sacral nerve roots (S2-S4) within the central canal, leading to a high incidence of bowel, bladder, and sexual dysfunction (cauda equina-like syndrome), manifesting as loss of perianal sensation and decreased anal sphincter tone.

Question 4494

Topic: 2. Trauma

A 25-year-old male undergoes intramedullary nailing of a femoral shaft fracture on a fracture table utilizing a perineal post. Post-operatively, he complains of numbness in his perineum and erectile dysfunction. What is the most appropriate initial management?

. Immediate surgical exploration
. Observation and reassurance
. Pelvic MRI
. Nerve conduction studies immediately
. Pudendal nerve decompression

Correct Answer & Explanation

. Immediate surgical exploration

Explanation

Pudendal nerve neuropraxia is a known complication of utilizing a perineal post on a fracture table, resulting from direct compression or traction. Symptoms include perineal numbness and erectile dysfunction. The vast majority of these injuries are transient and resolve completely with observation and supportive care over weeks to months.

Question 4495

Topic: 2. Trauma

A 68-year-old female sustains a 3-part proximal humerus fracture. Due to severe pain, comprehensive motor testing is difficult. What is the most sensitive and reliable physical examination maneuver to assess the integrity of the nerve most commonly injured in this setting?

. Assessment of sensation over the lateral aspect of the arm
. Assessment of sensation over the anatomical snuffbox
. Assessment of active shoulder elevation
. Assessment of active thumb extension
. Assessment for a positive Froment's sign

Correct Answer & Explanation

. Assessment of sensation over the lateral aspect of the arm

Explanation

The axillary nerve is the most frequently injured nerve in proximal humerus fractures. In the acute setting, pain often precludes reliable motor testing of the deltoid. Testing the sensation over the lateral aspect of the arm (regimental badge area), innervated by the superior lateral cutaneous nerve of the arm (a branch of the axillary nerve), is the most reliable way to assess its integrity.

Question 4496

Topic: 2. Trauma

A 10-year-old boy sustains a 'floating elbow' injury consisting of an ipsilateral displaced supracondylar humerus fracture and a both-bone forearm fracture. He is splinted in the emergency department. Two hours later, he develops severe, unrelenting pain in his forearm, and severe pain with passive extension of his fingers. What is the most appropriate NEXT step?

. Immediate fasciotomy in the operating room
. Elevation and application of ice
. Administer intravenous analgesia
. Remove all splinting material down to the skin and reassess
. Obtain an urgent MRI of the forearm

Correct Answer & Explanation

. Immediate fasciotomy in the operating room

Explanation

The patient is exhibiting classic signs of acute compartment syndrome. The most critical and immediate first step in management is the complete removal of all constrictive dressings, casts, and splints down to the skin. This simple maneuver can reduce compartmental pressures by up to 50-85%. If symptoms do not rapidly improve, emergent fasciotomy is indicated.

Question 4497

Topic: 2. Trauma
A 32-year-old male sustains a severe Hawkins type III talar neck fracture following a fall from height. Given the typical direction of displacement of the talar body in this specific fracture pattern, which neurovascular structure is at greatest risk of impingement or injury?
. Deep peroneal nerve
. Superficial peroneal nerve
. Sural nerve
. Saphenous nerve
. Tibial nerve

Correct Answer & Explanation

. Tibial nerve

Explanation

A Hawkins type III fracture is a talar neck fracture with dislocation of both the subtalar and tibiotalar joints. The talar body characteristically extrudes posteromedially. In this position, it places direct pressure on the posteromedial neurovascular bundle, putting the posterior tibial artery and the tibial nerve at high risk of injury.

Question 4498

Topic: 2. Trauma

A 45-year-old male patient with a historically malunited, highly displaced midshaft clavicle fracture presents with progressive upper extremity weakness, numbness, and tingling. Examination reveals intrinsic hand muscle wasting and sensory deficits along the medial aspect of the forearm and hand. Hypertrophic fracture callus is identified on imaging. Which nerve roots are most likely compressed in this form of Thoracic Outlet Syndrome?

. C5, C6
. C6, C7
. C7, C8
. C5, T1
. C8, T1

Correct Answer & Explanation

. C5, C6

Explanation

Malunited clavicle fractures with massive hypertrophic callus can cause secondary thoracic outlet syndrome (TOS). This typically results in compression of the lower trunk of the brachial plexus (C8 and T1 nerve roots) or the medial cord, as these structures pass inferior to the clavicle and over the first rib. Symptoms include ulnar neuropathy-like findings and intrinsic hand wasting.

Question 4499

Topic: 2. Trauma

A 34-year-old man sustains a Grade II open midshaft humerus fracture. On initial evaluation, he is unable to actively extend his wrist or fingers, and he has decreased sensation over the dorsal first web space. What is the most appropriate management of his nerve injury?

. Immediate exploration of the radial nerve during fracture debridement and fixation
. Closed reduction, splinting, and observation of the radial nerve
. EMG at 3 weeks to evaluate for reinnervation
. Tendon transfers within 1 week to restore hand function
. Ultrasound-guided perineural steroid injection

Correct Answer & Explanation

. Immediate exploration of the radial nerve during fracture debridement and fixation

Explanation

Immediate surgical exploration of the radial nerve is indicated in the setting of an open humerus shaft fracture associated with a radial nerve palsy. Closed fractures with primary palsies can typically be observed.

Question 4500

Topic: 2. Trauma
A 6-year-old child presents with a Bado Type III Monteggia fracture-dislocation. Following closed reduction, the patient cannot extend the fingers at the metacarpophalangeal joints but demonstrates normal wrist extension with radial deviation. What is the expected natural history of this neurologic deficit?
. Progressive worsening requiring urgent fascicular nerve grafting
. Permanent deficit requiring early tendon transfers
. Spontaneous recovery usually occurs within 3 to 6 months
. Indicates intra-articular entrapment requiring open release
. High likelihood of developing complex regional pain syndrome

Correct Answer & Explanation

. Spontaneous recovery usually occurs within 3 to 6 months

Explanation

The posterior interosseous nerve (PIN) is classically injured in Bado Type III (lateral) Monteggia fractures. It is almost always a neuropraxia that resolves spontaneously within 3 to 6 months without surgical intervention.

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