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1. General Principles & Basic Science MCQs

Practice Set 20 of 789

This practice set contains high-yield board review questions covering key concepts in 1. General Principles & Basic Science. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 381

Topic: 1. General Principles & Basic Science

A 6-year-old girl is diagnosed with Klippel-Feil syndrome based on a short neck, low posterior hairline, and fused cervical segments. Which organ system requires urgent screening due to a high incidence of life-threatening or functionally devastating, silent anomalies?

. Gastrointestinal tract
. Renal system
. Endocrine system
. Hematopoietic system
. Pulmonary system

Correct Answer & Explanation

. Renal system

Explanation

Klippel-Feil syndrome has a high association (up to 30%) with renal anomalies, such as unilateral renal agenesis. Renal ultrasound is mandatory to identify these potentially silent but significant abnormalities.

Question 382

Topic: 1. General Principles & Basic Science

An 8-year-old boy has had torticollis for approximately 5 weeks. He has undergone immobilization with a cervical collar without success. The patient has not undergone traction and now has atlantoaxial rotatory subluxation. The best treatment for this patient should be:

. C ontinued treatment in hard cervical orthosis
. Manipulation and closed reduction of his deformity
. Hospitalization with cervical traction
. Posterior C 1-C 2 fusion
. Application of halo vest and reduction

Correct Answer & Explanation

. Posterior C 1-C 2 fusion

Explanation

The treatment protocol for atlantoaxial rotatory subluxation is based on the onset and length of time of deformity. Soft collar treatment for this deformity is best if treated within 1 week of onset. For deformities lasting up to 1 month, in-house hospitalization with traction is warranted. However, the success of this treatment declines markedly after 1 month, at which time posterior C 1-C 2 fusion is warranted.

Question 383

Topic: 1. General Principles & Basic Science

During posterior cervical plating, several techniques can be employed. The recommended lateral mass screw position is:

. 10° laterally, 90° perpendicular to the lateral mass
. 50° cephalad and 30° laterally
. 30° laterally and 15° cephalad
. 15° laterally and 30° cephalad
. 60° laterally and 30° medially

Correct Answer & Explanation

. 30° laterally and 15° cephalad

Explanation

Surgical technique for cervical lateral mass fixation as described by An and colleagues is 30° of Lateral angulation and 15° of angulation cephalad to the facet joint.. This has been described as the safest recommended technique for lateral mass screw placement.

Question 384

Topic: 1. General Principles & Basic Science

A 25-year-old male presents with severe neck pain following a motor vehicle collision. Radiographs demonstrate a unilateral facet dislocation at C5-C6. What is the classic mechanism of this specific injury?

. Flexion-distraction
. Flexion-rotation
. Extension-compression
. Vertical compression
. Hyperextension

Correct Answer & Explanation

. Flexion-rotation

Explanation

Unilateral facet dislocations are primarily caused by a flexion-rotation mechanism. In contrast, bilateral facet dislocations are typically caused by pure flexion-distraction forces.

Question 385

Topic: Physiology & Rehabilitation

A 28-year-old male sustains a knife stab wound to the back, resulting in a spinal cord hemisection at T8. Which of the following clinical findings is expected below the level of the lesion?

. Ipsilateral loss of motor function and contralateral loss of pain sensation
. Ipsilateral loss of pain sensation and contralateral loss of motor function
. Bilateral loss of motor function
. Ipsilateral loss of proprioception and ipsilateral loss of pain sensation
. Bilateral loss of pain and temperature sensation

Correct Answer & Explanation

. Ipsilateral loss of motor function and contralateral loss of pain sensation

Explanation

Brown-Sequard syndrome (cord hemisection) causes ipsilateral loss of motor function and proprioception (corticospinal and dorsal columns cross high), and contralateral loss of pain and temperature (spinothalamic tract crosses early).

Question 386

Topic: 1. General Principles & Basic Science

What is the primary mechanism of injury responsible for a unilateral cervical facet dislocation?

. Flexion-distraction
. Flexion-rotation
. Extension-compression
. Vertical compression
. Hyperextension

Correct Answer & Explanation

. Flexion-rotation

Explanation

Unilateral facet dislocations typically occur via a flexion-rotation mechanism. This results in the disruption of the posterior ligamentous complex on one side, leading to less than 50% anterior translation of the vertebral body.

Question 387

Topic: 1. General Principles & Basic Science

When placing anterior pins for a halo vest orthosis in an adult, what is the anatomical safe zone to avoid injury to the supraorbital and supratrochlear nerves?

. Medial to the medial third of the eyebrow
. Directly superior to the pupil
. Lateral to the lateral two-thirds of the eyebrow
. 1 cm above the bridge of the nose
. Superior to the orbital rim in the midline

Correct Answer & Explanation

. Lateral to the lateral two-thirds of the eyebrow

Explanation

Anterior halo pins should be placed in the safe zone located lateral to the lateral two-thirds of the eyebrow, approximately above the equator of the eye. This placement avoids the medially located supraorbital and supratrochlear nerves and the frontal sinus.

Question 388

Topic: Physiology & Rehabilitation

A 25-year-old male sustains a stab wound to the right side of his T8 spinal cord. Which of the following classic clinical deficits will he exhibit?

. Right-sided loss of pain and temperature sensation
. Right-sided loss of motor function and proprioception
. Left-sided loss of motor function and proprioception
. Bilateral loss of pain and temperature sensation
. Left-sided loss of light touch only

Correct Answer & Explanation

. Right-sided loss of motor function and proprioception

Explanation

Brown-Sequard syndrome involves hemisection of the spinal cord. It causes ipsilateral loss of motor function and proprioception (due to damage to the corticospinal tract and dorsal columns) and contralateral loss of pain and temperature (spinothalamic tract).

Question 389

Topic: 1. General Principles & Basic Science
A 65-year-old man presents after a hyperextension injury to his neck. Neurological examination demonstrates a greater degree of motor weakness in his upper extremities compared to his lower extremities, along with variable sensory loss. Which of the following is the most likely diagnosis?
. Anterior cord syndrome
. Central cord syndrome
. Brown-Séquard syndrome
. Posterior cord syndrome
. Conus medullaris syndrome

Correct Answer & Explanation

. Central cord syndrome

Explanation

Central cord syndrome classically occurs after a hyperextension injury in older patients with preexisting cervical spondylosis. It presents with motor deficits that are disproportionately more severe in the upper extremities than the lower.

Question 390

Topic: 1. General Principles & Basic Science

A 35-year-old woman is evaluated after a fall. Cervical radiographs reveal a C5-C6 unilateral facet dislocation with approximately 25% anterior translation of C5 on C6. What is the typical mechanism of this injury?

. Flexion-distraction
. Hyperextension
. Axial compression
. Flexion-rotation
. Extension-rotation

Correct Answer & Explanation

. Flexion-rotation

Explanation

Unilateral facet dislocations are typically caused by a flexion-rotation mechanism. They classically present with approximately 25% anterior translation of the superior vertebral body on the lateral radiograph.

Question 391

Topic: 1. General Principles & Basic Science

During the application of a halo vest, the anterior pins are placed too medially, inside the lateral two-thirds of the orbit. Which of the following structures is at greatest risk of injury?

. Auriculotemporal nerve
. Supraorbital nerve
. Facial nerve
. Maxillary branch of the trigeminal nerve
. Greater occipital nerve

Correct Answer & Explanation

. Supraorbital nerve

Explanation

The safe zone for anterior halo pins is anterolateral, strictly lateral to the middle third of the orbit. Placement medial to this zone risks injury to the supraorbital and supratrochlear nerves, leading to painful neuromas or loss of forehead sensation.

Question 392

Topic: Physiology & Rehabilitation
A patient with a flexion teardrop fracture of C5 presents with profound loss of motor function, pain, and temperature sensation below the level of injury, but intact proprioception and vibratory sense. This presentation is characteristic of:
. Central cord syndrome
. Brown-Séquard syndrome
. Anterior cord syndrome
. Posterior cord syndrome
. Conus medullaris syndrome

Correct Answer & Explanation

. Anterior cord syndrome

Explanation

Anterior cord syndrome involves damage to the anterior two-thirds of the spinal cord, affecting the corticospinal (motor) and spinothalamic (pain/temperature) tracts. The dorsal columns (proprioception/vibration) are spared, but this syndrome has a poor prognosis for functional recovery.

Question 393

Topic: 1. General Principles & Basic Science

A 28-year-old man is intubated after a high-speed motor vehicle collision. A cross-table lateral radiograph demonstrates a Powers ratio of 1.3. What is the definitive treatment for this condition?

. Hard cervical collar for 12 weeks
. Halo vest application
. Anterior cervical plating
. Occipitocervical fusion
. C1-C2 transarticular screws

Correct Answer & Explanation

. Occipitocervical fusion

Explanation

A Powers ratio greater than 1 indicates an anterior occipitocervical dissociation, a highly unstable and potentially lethal injury. Due to purely ligamentous disruption, definitive treatment requires rigid surgical stabilization via posterior occipitocervical fusion.

Question 394

Topic: Physiology & Rehabilitation
A patient sustains a penetrating knife wound to the right side of the T8 spinal cord. Which of the following best describes the expected neurologic deficits below the level of the injury?
. Right-sided loss of pain and temperature, left-sided loss of motor function
. Left-sided loss of motor function, right-sided loss of proprioception
. Right-sided loss of motor function, left-sided loss of pain and temperature
. Left-sided loss of proprioception only
. Symmetrical loss of all sensory modalities

Correct Answer & Explanation

. Right-sided loss of motor function, left-sided loss of pain and temperature

Explanation

This describes Brown-Séquard syndrome (spinal cord hemisection). It results in ipsilateral loss of motor function and proprioception (corticospinal and dorsal columns) and contralateral loss of pain and temperature sensation (spinothalamic tract).

Question 395

Topic: 1. General Principles & Basic Science

An 8-year-old boy presents with a painless limp and restricted hip internal rotation. Radiographs demonstrate fragmentation of the capital femoral epiphysis with 60% involvement of the lateral pillar. According to the Herring Lateral Pillar Classification, which group does this represent?

. Group A
. Group B
. Group B/C border
. Group C
. Group D

Correct Answer & Explanation

. Group C

Explanation

In Herring's Lateral Pillar Classification, Group B involves >50% maintenance of lateral pillar height. Group C has <50% height, and Group A has no lateral pillar involvement.

Question 396

Topic: Infection, Pharmacology & VTE
A 5-year-old boy presents with right hip pain, a limp, and a temperature of 38.8°C. He refuses to bear weight. His WBC is 13,000/mm³ and ESR is 45 mm/hr. According to the Kocher criteria, what is the probability that this child has septic arthritis rather than transient synovitis?
. < 5%
. 15%
. 40%
. 93%
. 99%

Correct Answer & Explanation

. 93%

Explanation

The Kocher criteria include: non-weight-bearing, temperature >38.5°C, ESR >40 mm/hr, and WBC >12,000/mm³. Having 3 out of 4 criteria gives a 93% predictive probability for septic arthritis.

Question 397

Topic: Biology, Genetics & Bone Healing

A 6-year-old boy presents with medial midfoot pain and a limp for 2 months. Radiographs reveal sclerosis and flattening of the navicular bone. What is the most appropriate initial management?

. Surgical excision of the navicular
. Corticosteroid injection
. Observation and short leg walking cast for severe symptoms
. Tibiotalocalcaneal arthrodesis
. Bisphosphonate therapy

Correct Answer & Explanation

. Observation and short leg walking cast for severe symptoms

Explanation

Kohler disease is an avascular necrosis of the navicular that is typically self-limiting. Treatment consists of observation or, in highly symptomatic cases, a short leg walking cast for 4 to 6 weeks to alleviate pain.

Question 398

Topic: Infection, Pharmacology & VTE

A 3-year-old boy presents with a temperature of 38.8 C, refusal to bear weight on his right leg, an ESR of 55 mm/hr, and a serum WBC of 14,000/mm3 with suspected hip pathology. According to Kocher criteria, what is the statistical probability of septic arthritis?

. 40%
. 55%
. 71%
. 93%
. 99%

Correct Answer & Explanation

. 99%

Explanation

The Kocher criteria for septic arthritis of the hip include non-weight-bearing, temperature >38.5 C, ESR >40 mm/hr, and WBC >12,000/mm3. Having all 4 predictors yields a 99% probability of septic arthritis.

Question 399

Topic: Infection, Pharmacology & VTE

Which of the following toxins is responsible for the virulence of community- acquired methicillin-resistant Staphylococcus aureus (C A-MRSA):

. Beta-lactam
. Panton-Valentine leukocidin
. Oxazolidine
. mecA
. Streptolysin

Correct Answer & Explanation

. Panton-Valentine leukocidin

Explanation

Panton-Valentine leukocidin is a toxin that produces necrosis of tissue and white blood cells. This toxin is much more common in CA-MRSA than in hospital-acquired MRSA.

Question 400

Topic: Infection, Pharmacology & VTE

A 5-year-old girl presents to the emergency department with pain in her hip. Her temperature is 102° F, pulse is 96, and blood pressure is 104/60. Magnetic resonance imaging reveals edema in the obturator muscles. Blood cultures are negative. Ultrasound-guided aspiration reveals no abscess, but fluid obtained grows methicillin-resistant Staphylococcus aureus (MRSA). In addition to antibiotic treatment, what other treatment option is recommended:

. Surgical irrigation and debridement
. Indwelling catheter drainage
. Repeated aspiration with ultrasound guidance
. Observation
. Spica cast application

Correct Answer & Explanation

. Observation

Explanation

This patient has community-acquired MRSA but does not have an evident fluid collection. There is no evidence of systemic infection or necrotizing fasciitis. There is no indication for drainage or debridement of any type. Therefore, antibiotics alone with clinical observation are indicated.

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