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1. General Principles & Basic Science MCQs

Practice Set 13 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 241

Topic: 1. General Principles & Basic Science

In the standard measurement of lumbar lordosis using the Cobb angle method on a standing lateral radiograph, which anatomical landmarks are most commonly utilized?

. Superior endplate of T12 and inferior endplate of L5
. Superior endplate of L1 and superior endplate of S1
. Inferior endplate of T12 and superior endplate of L5
. Superior endplate of L2 and inferior endplate of S1
. Inferior endplate of L1 and inferior endplate of L5

Correct Answer & Explanation

. Superior endplate of L1 and superior endplate of S1

Explanation

Global lumbar lordosis is standardly measured as the Cobb angle between the superior endplate of L1 and the superior endplate of S1. The majority of this lordosis normally occurs distally between L4 and S1.

Question 242

Topic: 1. General Principles & Basic Science

The T1 Pelvic Angle (TPA) is a measure of global sagittal alignment. It is defined as the angle between a line from the center of the femoral heads to the center of the S1 endplate, and a line from the femoral heads to the:

. Anterior border of T1
. Center of the T1 vertebral body
. Posterior elements of T1
. Superior endplate of T1
. Inferior endplate of T1

Correct Answer & Explanation

. Center of the T1 vertebral body

Explanation

The T1 Pelvic Angle (TPA) is constructed by drawing a line from the femoral heads to the center of the T1 body and another to the center of the S1 superior endplate. A TPA greater than 14 degrees indicates significant sagittal deformity.

Question 243

Topic: Surgical Anatomy & Approaches

A 45-year-old female presents with a rigid, focal, angular kyphotic deformity of 65 degrees following an old burst fracture. To achieve optimal correction, which of the following osteotomies is most indicated?

. Multiple Smith-Petersen Osteotomies (SPO)
. Ponte Osteotomies
. Pedicle Subtraction Osteotomy (PSO)
. Vertebral Column Resection (VCR)
. Anterior Longitudinal Ligament release

Correct Answer & Explanation

. Vertebral Column Resection (VCR)

Explanation

Vertebral Column Resection (VCR) is a three-column osteotomy involving complete removal of the vertebral body and posterior elements. It is indicated for rigid, focal, and severe coronal or sagittal deformities exceeding 40 degrees where a PSO would be insufficient.

Question 244

Topic: Surgical Anatomy & Approaches

A surgeon plans to perform a Smith-Petersen osteotomy (SPO) to correct a sagittal deformity. Which of the following is a strict prerequisite for an SPO to effectively induce lordosis?

. An ossified anterior longitudinal ligament
. A mobile anterior disc space
. A fused posterior column
. Previous total disc replacement
. Severe anterior wedging of the vertebral body

Correct Answer & Explanation

. A mobile anterior disc space

Explanation

An SPO relies on hinging through the posterior column while the anterior column acts as an opening wedge. Therefore, a mobile anterior disc space is an absolute prerequisite for the osteotomy to close posteriorly and successfully achieve lordosis.

Question 245

Topic: Surgical Anatomy & Approaches

A 40-year-old male with iatrogenic flatback syndrome requires surgical correction. The surgeon plans a Pedicle Subtraction Osteotomy (PSO) at L3. Approximately how many degrees of sagittal correction can be expected from a single-level standard PSO?

. 5 to 10 degrees
. 10 to 15 degrees
. 30 to 40 degrees
. 50 to 60 degrees
. 70 to 80 degrees

Correct Answer & Explanation

. 30 to 40 degrees

Explanation

A pedicle subtraction osteotomy (PSO) is a three-column closing wedge osteotomy that typically provides 30 to 40 degrees of sagittal correction at a single level. In contrast, a Smith-Petersen Osteotomy (SPO) yields about 10 degrees per level.

Question 246

Topic: Surgical Anatomy & Approaches

A patient with rigid positive sagittal imbalance requires 30 degrees of lordotic correction at a single level. Which of the following techniques is most appropriate to achieve this exact degree of correction?

. Single Smith-Petersen Osteotomy (SPO)
. Multiple contiguous Ponte osteotomies
. Pedicle Subtraction Osteotomy (PSO)
. Anterior Lumbar Interbody Fusion (ALIF) alone
. Vertebral Column Resection (VCR)

Correct Answer & Explanation

. Pedicle Subtraction Osteotomy (PSO)

Explanation

A Pedicle Subtraction Osteotomy (PSO) is a three-column, closing wedge osteotomy that typically provides 30 to 35 degrees of sagittal correction at a single level. In contrast, an SPO provides approximately 10 degrees per level.

Question 247

Topic: Infection, Pharmacology & VTE

Which of the following is the most common organism identified in cases of vertebral osteomyelitis:

. Staphylococcus aureus
. Streptococcus pneumoniae
. Haemophilus influenzae
. Escherichia coli
. Anaerobic gram-negative rods

Correct Answer & Explanation

. Staphylococcus aureus

Explanation

Staphylococcus aureus remains the most common causative organism, but an increasing proportion of cases are due to gramnegative and anaerobic organisms such as Proteus, Escherichia coli and Pseudomonas.

Question 248

Topic: Infection, Pharmacology & VTE
Which of the following is the most common presentation of vertebral osteomyelitis?
. Fever of unknown origin
. Lower extremity pain and weakness
. Unrelenting back pain not relieved by rest
. Urinary incontinence
. None of the above. It is usually an incidental finding during an unrelated work-up.

Correct Answer & Explanation

. Unrelenting back pain not relieved by rest

Explanation

The most common presenting sign of vertebral osteomyelitis is back pain and malaise, often of 3 months' duration or greater. It is often well localized to the affected level and the nature is not unlike most degenerative spinal conditions. A high index of suspicion is essential to make a timely diagnosis. Back pain that awakens a patient at night is a hallmark of infection or tumor. Pain associated with infection tends to be relentless and not related to activity level. Most patients have percussion tenderness over the involved segments. Fevers are noted in fewer than half of patients.

Question 249

Topic: Infection, Pharmacology & VTE

Which of the following is the hallmark distinguishing feature of vertebral osteomyelitis when compared to a neoplastic process on imaging:

. Uniform enhancement after administration of gadolinium in the neoplasia
. Destruction of disk space and encroachment of adjacent vertebral body in vertebral osteomyelitis
. Lack of endplate involvement in the neoplastic process
. Evidence of a compression fracture in vertebral osteomyelitis
. There are no distinguishing radiographic features between vertebral osteomyelitis and a tumor.

Correct Answer & Explanation

. Destruction of disk space and encroachment of adjacent vertebral body in vertebral osteomyelitis

Explanation

The crossing of the infectious process along the disk space to involve adjacent vertebrae is a hallmark feature of osteomyelitis used to differentiate it from a neoplastic process.

Question 250

Topic: 1. General Principles & Basic Science

Which of the following is the imaging modality of choice with the highest relative sensitivity and specificity in patients with suspected vertebral osteomyelitis:

. Plain radiography
. C omputed tomography with contrast administration
. Magnetic resonance imaging with contrast administration
. Post myelogram computed tomography
. Vertebral osteomyelitis is primarily a clinical diagnosis

Correct Answer & Explanation

. Magnetic resonance imaging with contrast administration

Explanation

Magnetic resonance imaging (MRI) is the modality of choice for spinal infections. An MRI study provides excellent visualization of the neural elements and can determine whether the inflammatory process extends beyond the margins of disk and bone. MRI also provides excellent regional anatomic information. Scans performed with and without intravenous gadolinium are diagnostic in 90% to 95% of cases.

Question 251

Topic: Biology, Genetics & Bone Healing

A 65-year-old woman with known osteoporosis sustains an acute L1 compression fracture after lifting a box. She is neurologically intact, and her pain is adequately managed with oral analgesics. What is the most appropriate initial treatment?

. Posterior spinal fusion
. Anterior corpectomy and fusion
. Kyphoplasty
. Vertebroplasty
. Observation with early mobilization and pain control

Correct Answer & Explanation

. Observation with early mobilization and pain control

Explanation

The standard of care for neurologically intact, stable osteoporotic compression fractures is non-operative management. Early mobilization, pain control, and treatment of the underlying osteoporosis are recommended over immediate surgical intervention.

Question 252

Topic: 1. General Principles & Basic Science
A 65-year-old man with underlying cervical spondylosis falls forward, striking his chin. He presents with profound bilateral upper extremity weakness but relatively preserved lower extremity strength. What 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 in elderly patients with pre-existing cervical spondylosis following a hyperextension injury. It presents with disproportionate upper extremity weakness compared to the lower extremities.

Question 253

Topic: 1. General Principles & Basic Science

When applying a halo vest in an adult, the anterior pins should be placed precisely to avoid neurovascular injury. Which of the following nerves is at greatest risk if the anterior pins are placed too far medially?

. Auriculotemporal nerve
. Supraorbital nerve
. Facial nerve
. Trigeminal nerve (mandibular branch)
. Greater occipital nerve

Correct Answer & Explanation

. Supraorbital nerve

Explanation

The anterior pins of a halo ring must be placed in the safe zone, which is 1 cm above the lateral one-third of the eyebrow. Placing the pins medially risks injury to the supraorbital and supratrochlear nerves.

Question 254

Topic: 1. General Principles & Basic Science

A unilateral cervical facet dislocation is typically the result of which mechanism of injury?

. Pure axial loading
. Flexion and distraction
. Flexion and rotation
. Extension and compression
. Pure hyperextension

Correct Answer & Explanation

. Flexion and rotation

Explanation

Unilateral facet dislocations typically occur due to a flexion-rotation injury, causing one inferior articular process to jump anterior to the superior articular process below it. Bilateral dislocations are primarily caused by severe flexion-distraction.

Question 255

Topic: Physiology & Rehabilitation
A 28-year-old sustains a stab wound to the back resulting in Brown-Séquard syndrome at the T10 level. Which of the following accurately describes the expected neurological deficit below the level of injury?
. Bilateral loss of motor function below T10
. Ipsilateral loss of pain and temperature sensation below T10
. Contralateral loss of motor function below T10
. Ipsilateral loss of motor function and contralateral loss of pain and temperature sensation
. Contralateral loss of proprioception and vibratory sense below T10

Correct Answer & Explanation

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

Explanation

Brown-Séquard syndrome results from spinal cord hemisection. It classically presents with ipsilateral loss of motor function, proprioception, and vibratory sense (corticospinal and dorsal columns), and contralateral loss of pain and temperature sensation (spinothalamic tract).

Question 256

Topic: 1. General Principles & Basic Science

Untreated low back pain most commonly:

. Improves spontaneously
. Undergoes progressive worsening prompting further medical care
. Leads to neurological decompensation
. No studies have been done to evaluate the natural history of untreated low back pain.
. Progresses to chronic failed back syndrome

Correct Answer & Explanation

. Improves spontaneously

Explanation

Generally, patients diagnosed with low back pain should undergo 4 weeks of conservative treatment with an accepted prognosis of predominantly spontaneous improvement over a 4-week period, regardless of treatment.

Question 257

Topic: 1. General Principles & Basic Science

Which of the following is the primitive remnant of the nucleus pulposus:

. The smoites
. Ectoderm
. Midgut
. Rhombencephalon
. Notocord

Correct Answer & Explanation

. Notocord

Explanation

The nucleus pulposus is derived from the primitive notochord. It consists predominantly of hydrated proteoglycans with a minor component of a random network of type I and type II collagen.

Question 258

Topic: Infection, Pharmacology & VTE

A 55-year-old poorly controlled diabetic male presents with fevers, severe localized back pain, and an elevated CRP. MRI reveals fluid in the L3-L4 disc space and adjacent vertebral body edema. What is the most common causative organism for this condition?

. Pseudomonas aeruginosa
. Staphylococcus aureus
. Escherichia coli
. Mycobacterium tuberculosis
. Streptococcus pneumoniae

Correct Answer & Explanation

. Staphylococcus aureus

Explanation

Staphylococcus aureus is the most common organism responsible for pyogenic vertebral osteomyelitis and discitis. While Pseudomonas is a notable risk in IV drug users, S. aureus remains the most common overall.

Question 259

Topic: 1. General Principles & Basic Science

The type of peripheral nerve injury that requires acute repair is:

. A sharp transection
. A blunt transection
. A contusion injury
. A stretch injury
. No peripheral nerve injury should be acutely repaired.

Correct Answer & Explanation

. A sharp transection

Explanation

The type of traumatic peripheral nerve injury dictates the timing of repair. If a nerve has been sharply transected, then repair should be performed within 72 hours. This can be accomplished during the repair of associated skin, vessels, muscles, and tendons. For a sharply transected but partially cut nerve, early repair is also recommended. Bluntly transected nerves require delayed repair. Contusion and stretch injuries may require delayed surgery.

Question 260

Topic: 1. General Principles & Basic Science

The proper treatment plan for contusion and stretch peripheral nerve injuries involves:

. Immediate surgical exploration and repair
. Delayed surgical repair 2 weeks after injury
. Immediate surgical exploration followed by delayed repair weeks to months later
. Observation only
. Observation followed by delayed surgical exploration if no functional recovery is found

Correct Answer & Explanation

. Observation followed by delayed surgical exploration if no functional recovery is found

Explanation

For contusion and stretch peripheral nerve injuries, delayed surgery is recommended. Patients are followed for several weeks to months and monitored for functional nerve recovery. If there is no evidence of regeneration, then surgical exploration is performed.

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