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6. Spine MCQs

Practice Set 67 of 379

This practice set contains high-yield board review questions covering key concepts in 6. Spine. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 1321

Topic: 6. Spine

A prospective cohort study is designed to evaluate the risk of postoperative surgical site infection following spinal fusion in diabetic versus non-diabetic patients. Which of the following statistical measures is most appropriate to report the strength of association in this specific study design?

. Odds ratio
. Relative risk
. Hazard ratio
. Pearson correlation coefficient
. Number needed to treat

Correct Answer & Explanation

. Relative risk

Explanation

Relative risk (RR) is the appropriate measure of association for cohort studies, comparing the incidence of disease in exposed versus unexposed groups. Odds ratios are typically used in case-control studies.

Question 1322

Topic: 6. Spine

Diastematomyelia is best described as:

. Protrusion of neural elements dorsally from the back.
. A duplicated spinal column.
. Two hemivertebrae at adjacent levels.
. An osseous or fibrocartilaginous septum in the spinal canal.
. A cyst within the spinal cord.

Correct Answer & Explanation

. An osseous or fibrocartilaginous septum in the spinal canal.

Explanation

A diastematomyelia is an osseous or fibrocartilaginous septum within the spinal canal that invaginates or splits the neural tissue. A diastematomyelia may or may not be associated with neurologic deficit. Surgical excision is indicated for the presence of symptoms or at the time of spinal deformity correction.

Question 1323

Topic: 6. Spine

Diastematomyelia is most common in which region of the spine:

. C ervical
. Upper thoracic
. Lower thoracic
. Lumbar
. Sacral

Correct Answer & Explanation

. Lumbar

Explanation

Several series of patients with diastematomyelia have shown the following anatomic distribution: 64% occur in the lumbar spine, 27% occur in the lower thoracic spine, 9% in the upper thoracic spine, and almost none occur in the cervical or sacral regions.

Question 1324

Topic: 6. Spine

The somite refers to which of the following features of embryologic development:

. A group of cells that produce the limb bud
. A structure that gives rise to the spinal cord
. A group of cells that differentiate to form the cranium
. A group of cells that are repeated to form the axial skeleton
. A set of homeobox genes

Correct Answer & Explanation

. A group of cells that are repeated to form the axial skeleton

Explanation

The somite is a group of tissues that are bilaterally symmetric and repeated to comprise the axial skeleton. Each somite contains a dermatome, myotome, and sclerotome.

Question 1325

Topic: Thoracolumbar Spine & Deformity
An appropriate indication for preoperative MRI in adolescent idiopathic scoliosis is:
. Any curve requiring surgery
. Any curve more than 90°
. An abnormal neurologic examination
. Any progressive deformity in a male
. Any progression of 12° in 6 months

Correct Answer & Explanation

. An abnormal neurologic examination

Explanation

The only absolute indication for preoperative MRI in idiopathic adolescent scoliosis is an abnormal neurologic exam or abnormal curve pattern.

Question 1326

Topic: Thoracolumbar Spine & Deformity
The mean Cobb measurement for idiopathic scoliosis curves with a 7° angle of trunk rotation (ATR) is:
. 10°
. 15°
. 20°
. 25°
. 30°

Correct Answer & Explanation

. 20°

Explanation

Although the angle of trunk rotation (ATR) does not convert directly to a Cobb angle, there are population-based figures for mean curve at each ATR. The mean Cobb angle for curves having a 7° ATR is 20°.

Question 1327

Topic: Thoracolumbar Spine & Deformity

The normal values (±2 standard deviations) for kyphosis in the general population of children and adolescents are:

. 20° to 50°
. 20° to 40°
. 25° to 45°
. 25° to 60°
. 30° to 60°

Correct Answer & Explanation

. 20° to 50°

Explanation

The normal values for kyphosis in the general population (2 standard deviations above and below the mean) are 20° to 50°.

Question 1328

Topic: 6. Spine

Which of the following is the central element of Klippel-Feil syndrome:

. A low posterior hairline
. Hearing impairment
. C ervical stenosis
. C ongenital cervical fusion
. C ervical scoliosis

Correct Answer & Explanation

. C ongenital cervical fusion

Explanation

The essential feature of the definition of Klippel-Feil syndrome is congenital cervical fusion. Features other than congenital cervical fusion are sometimes seen but are not essential features of the syndrome. Features other than those listed above include scoliosis in different regions of the spine, congenital heart defects, a short neck, Sprengel deformity, and renal anomalies.

Question 1329

Topic: Thoracolumbar Spine & Deformity

The most common cause of neurologic deficit in patients with Down syndrome is:

. Basilar invagination
. Atlanto-occipital instability
. Atlantoaxial instability
. Subaxial instability
. C ervical kyphosis

Correct Answer & Explanation

. Atlantoaxial instability

Explanation

Basilar invagination is extremely rare in this syndrome, and problematic cervical kyphosis is equally uncommon. Atlanto-occipital translation and subaxial instability occur but rarely cause symptoms. Atlantoaxial instability is the most common of the cervical abnormalities listed to cause neurologic compromise in Down syndrome. Nevertheless, surgery is only indicated if the atlantoaxial interval exceeds 6 mm, or causes neurologic deficits.

Question 1330

Topic: 6. Spine
A 15-year-old with idiopathic scoliosis develops a temperature of 39.5° C 8 days after posterior spinal fusion with instrumentation. Blood and urine cultures show no growth, and chest X-ray is normal. Your next step should be which of the following?
. Begin intravenous cephalosporin treatment
. Begin intravenous vancomycin treatment
. Aspirate the wound for culture
. Debride the wound and remove the instrumentation
. Debride the wound and remove the bone graft

Correct Answer & Explanation

. Aspirate the wound for culture

Explanation

There is a significant likelihood of a deep wound infection, although other possibilities exist, including superficial wound infection, atelectasis, and drug-related fever. Therefore, confirmation of the diagnosis is the next step. The wound should be aspirated for culture next. If infection is confirmed, the wound should be opened and debrided.

Question 1331

Topic: 6. Spine

Nine days after surgery, a 16-year-old boy with idiopathic scoliosis has a temperature of 39.5° C . Wound aspiration reveals gram-positive cocci in clusters. Your next step in management is:

. Begin intravenous cephalosporin and monitor the response
. Begin intravenous vancomycin and monitor the response
. Begin hyperbaric oxygen and intravenous antibiotics
. Open and debride the wound, leaving the instrumentation in place
. Open and debride the wound, and remove the instrumentation

Correct Answer & Explanation

. Open and debride the wound, and remove the instrumentation

Explanation

Open debridement is the treatment of choice if an early deep wound infection is confirmed after spinal fusion. The instrumentation is left in place to stabilize the wound and promote fusion. The wound is closed as long as it can be cleaned up adequately during surgery, and muscle has a healthy appearance. If this cannot be achieved or if several debridements fail, the wound may be left open.

Question 1332

Topic: Thoracolumbar Spine & Deformity
A thoracic curve of more than 50° due to an idiopathic adolescent scoliosis curve has an increased risk of causing all except which of the following consequences in adulthood, when compared to the general population:
. Restrictive lung disease
. Obstructive lung disease
. Back pain
. Less positive body image
. Increase in curvature

Correct Answer & Explanation

. Restrictive lung disease

Explanation

Idiopathic adolescent scoliosis is likely to progress in adulthood if it exceeds 50°. The rate of progression in adults is slower than during adolescence; about 1° per year. Nevertheless, it is likely to have some effect on pulmonary function later during adulthood. The effect is one of restrictive rather than obstructive lung disease. There is an increase in the risk of back pain, although it is rarely disabling. Patients with idiopathic scoliosis as a group have a more negative body image, although it is not a serious life impairment. In all of these parameters, there are individual exceptions.

Question 1333

Topic: 6. Spine

A 13-year-old girl with idiopathic adolescent scoliosis has a 32° right thoracolumbar curve. Her Risser sign is 1. Her curve measured 29° 4 months ago. You recommend:

. Observing until the curve reaches 34°
. Ordering a magnetic resonance image of the spine
. Physical therapy to control the curve
. Electrical stimulation to the paraspinal muscles
. A thoracolumbosacral orthosis

Correct Answer & Explanation

. A thoracolumbosacral orthosis

Explanation

Idiopathic scoliosis in skeletally immature patients should be braced if it is greater than 30° and significant growth remains (estimated by a Risser sign of 0, 1, or 2). Studies have shown that patients with idiopathic scoliosis without atypical findings do not need magnetic resonance imaging. Physical therapy and electrical stimulation have been shown not to have any effect on the progression of idiopathic scoliosis.

Question 1334

Topic: Thoracolumbar Spine & Deformity
Which of the following factors are not related to the success of brace treatment for idiopathic scoliosis?
. Curve size at start of treatment
. Curve correction in brace
. Number of hours worn
. Gender
. Positive family history of scoliosis

Correct Answer & Explanation

. Positive family history of scoliosis

Explanation

A lower chance of curve control with brace treatment has been shown with curves greater than 40°, correction of less than 50% in brace, brace worn fewer than 16 hours per day, or male gender. Positive family history has not been shown to be related to curve progression or chance of control.

Question 1335

Topic: Thoracolumbar Spine & Deformity

A 12-year-old patient has a rigid, 135° scoliosis. Gradually increasing halo- gravity traction is planned in correcting the curve. The maximum weight that should be used is:

. 15% of body weight
. 20% of body weight
. 25% of body weight
. 30% of body weight
. 35% to 45% of body weight

Correct Answer & Explanation

. 35% to 45% of body weight

Explanation

Halo-gravity traction is a safe and effective means of gradually correcting large curves. It allows balanced force application and continuous neurological monitoring. C ranial and peripheral nerves should be monitored. The weight can be increased gradually up to 35% to 45% of body weight, as documented in published series.

Question 1336

Topic: 6. Spine

After the bone age of 15 years, boys will achieve the most growth from which of the following regions:

. Distal femoral epiphysis
. Proximal tibial epiphysis
. Distal tibial epiphysis
. Ilium and pelvis
. Spine

Correct Answer & Explanation

. Spine

Explanation

After the age of 15 in boys (13 in girls), most of the growth (4.5 cm on average) occurs in the spine.

Question 1337

Topic: 6. Spine

The most accurate way to monitor the motor tracts during spinal surgery is to stimulate which of the following regions:

. Tibial nerve
. Peroneal nerve
. Motor cortex
. Gastrocnemius
. Proximal spinal cord

Correct Answer & Explanation

. Motor cortex

Explanation

The most accurate way to monitor the motor tracts of the spinal cord is to stimulate the motor cortex. Stimulation at the level of the spinal cord conducts mainly antidromically through sensory pathways. Stimulation of the tibial and peroneal nerve is performed for monitoring sensory pathways only; these are an important indicator of spinal cord integrity but do not monitor the motor pathways per se. Stimulation of the gastrocnemius does not have any value for monitoring.

Question 1338

Topic: Thoracolumbar Spine & Deformity

Which of the following is the greatest risk factor for the progression of isthmic spondylolisthesis in a pediatric patient?

. Male gender
. Presentation after age 15
. High slip angle (>45 degrees)
. Low pelvic incidence
. Grade I initial slippage

Correct Answer & Explanation

. High slip angle (>45 degrees)

Explanation

A high slip angle, typically greater than 45 to 50 degrees, is the most significant radiographic predictor for the progression of isthmic spondylolisthesis. Other risk factors include young age at presentation, female gender, and dysplastic morphology.

Question 1339

Topic: 6. Spine

During posterior spinal fusion for severe adolescent idiopathic scoliosis, a sudden drop in somatosensory evoked potentials (SSEPs) and motor evoked potentials (MEPs) is noted following deformity correction. What is the most likely neurologic syndrome if the cord becomes ischemic?

. Central cord syndrome
. Brown-Sequard syndrome
. Posterior cord syndrome
. Anterior cord syndrome
. Cauda equina syndrome

Correct Answer & Explanation

. Anterior cord syndrome

Explanation

Spinal cord ischemia during scoliosis surgery, typically due to over-distraction or hypotension, preferentially affects the anterior spinal artery watershed areas. This leads to anterior cord syndrome, which presents with motor paralysis and loss of pain/temperature sensation but preserved dorsal column function (proprioception).

Question 1340

Topic: 6. Spine

In the Levine-Edwards classification of traumatic spondylolisthesis of the axis, which mechanism is associated with a Type IIA fracture?

. Hyperextension and axial loading
. Flexion and distraction
. Flexion and compression
. Extension and distraction
. Rotational shear

Correct Answer & Explanation

. Flexion and distraction

Explanation

Type IIA Hangman's fractures are caused by flexion and distraction, resulting in severe angulation with minimal translation. Traction is strictly contraindicated as it can exacerbate the deformity and cause neurologic injury.

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